Id,Abstract,Summary,
!001,"Efficient storage technology (absorption and desorption) is the key to boom the application of hydrogen as energy storage media. Among the solid-state hydrogen storage materials, magnesium-based material exhibits many advantages and is considered one of the most promising materials. However, the disadvantages including poor hydrogen absorption, desorption kinetics and high operating temperature still need to be modified. The addition of catalysts is one of the optimal ways to improve the kinetic performance of MgH2. However, transition metal-based catalysts exhibit excellent catalytic performance. This work mainly summarizes the addition of Co/Ni/Fe-based catalysts on the hydrogen storage performances of Mg. While examining the differences in the performance of each catalyst, some future research perspectives are also illustrated. ","Among the solid-state hydrogen storage materials, magnesium-based material exhibits many advantages and is considered one of the most promising materials. However, the disadvantages including poor hydrogen absorption, desorption kinetics and high operating temperature still need to be modified.",_
!002,"Developing safer and more efficient hydrogen storage technology is a pivotal step to realizing the hydrogen economy. Owing to the lightweight, high hydrogen storage density and abundant reserves, MgH2 has been widely studied as one of the most promising solid-state hydrogen storage materials. However, defects such as stable thermodynamics, sluggish kinetics and rapid capacity decay have seriously hindered its practical application. This article reviews recent advances in catalyst doping and nanostructures for improved kinetic performance of MgH2/Mg systems for hydrogen release/absorption, the tuning of their thermodynamic stability properties by alloying and reactant destabilization, and the dual thermodynamic and kinetic optimization of the MgH2/Mg system achieved by nanoconfinement with in situ catalysis and ball milling with in situ aerosol spraying, aiming to open new perspectives for the scale-up of MgH2 for hydrogen storage applications. ","Owing to the lightweight, high hydrogen storage density and abundant reserves, MgH2 has been widely studied as one of the most promising solid-state hydrogen storage materials. However, defects such as stable thermodynamics, sluggish kinetics and rapid capacity decay have seriously hindered its practical application.",_
!003,"MgH2, as one of the typical solid-state hydrogen storage materials, has attracted extensive attention. However, the slow kinetics and poor cycle stability limit its application. In this work, LiBH4 and YNi5 alloy were co-added as additives to MgH2 via ball milling, thereby realizing an excellent dehydrogenation performance and good cycle stability at 300 °C. The MgH2-0.04LiBH4-0.01YNi5 composite can release 7 wt.% of hydrogen in around 10 min at 300 °C and still have a reversible hydrogen storage capacity of 6.42 wt.% after 110 cycles, with a capacity retention rate as high as 90.3 % based on the second dehydrogenation capacity. The FTIR results show that LiBH4 can reversibly absorb and desorb hydrogen throughout the hydrogen ab/desorption process, which contributes a portion of the reversible hydrogen storage capacity to the MgH2-0.04LiBH4-0.01YNi5 composite. Due to the small amount of LiBH4 and YNi5, the dehydrogenation activation energy of MgH2 did not decrease significantly, nor did the dehydrogenation enthalpy (∆H) change. However, the MgNi3B2 and in-situ formed YH3 during the hydrogen absorption/desorption cycles is not only beneficial to the improvement of the kinetics performance for MgH2 but also improves its cycle stability. This work provides a straightforward method for developing high reversible hydrogen capacity on Mg-based hydrogen storage materials with moderate kinetic performance. ","MgH2, as one of the typical solid-state hydrogen storage materials, has attracted extensive attention. However, the slow kinetics and poor cycle stability limit its application.",_
!004,"MgH2 has been attracted extensive attention because of its superior hydrogen storage performance and good reversibility. Further improvement of its kinetics and thermodynamic performances is needed to achieve widespread application. This article investigated the hydrogen storage properties of the thermodynamic optimized Mg-TiCrV hydrogen storage composite modified by layered Ti3C2 materials containing different 3d transition metal particles (Fe, Co, Ni). Mg-TiCrV/Ti3C2-X (X = Fe, Co, Ni) composites can absorb more than 5.30 wt% hydrogen within 1 min at 453 K under 3 MPa hydrogen pressure, and desorb more than 5.25 wt% hydrogen within 60 min at 543 K to 0.1 MPa. In particular, Mg-TiCrV/Ti3C2-Ni composite exhibited the best hydrogen storage properties, which can desorb 4.98 wt% hydrogen within 60 min at 523 K to 0.1 MPa hydrogen pressure and absorb 5.80 wt% hydrogen within 1 min at 453 K under 3 MPa hydrogen pressure. Structural analysis shows that the synergistic effect of layered material Ti3C2 and Ni particles promote the hydrogen release and uptake process. ",MgH2 has been attracted extensive attention because of its superior hydrogen storage performance and good reversibility. Further improvement of its kinetics and thermodynamic performances is needed to achieve widespread application.,_
!005,"The design of catalysts with excellent catalytic activity plays an important role in the field of solid-state hydrogen storage of new energy sources. Herein, a novel hydrangea-like NiO@NiMoO4 composite catalyst was prepared through a facile hydrothermal reaction. Subsequently, NiO@NiMoO4 was doped into MgH2 by ball milling to solve the problems of high dehydrogenation temperature and slow desorption kinetics of MgH2. It can be seen from the experimental results that the MgH2 + 10 wt% NiO@NiMoO4 composite starts to dehydrogenate at about 190 °C, which is about 170 °C lower than that of pure MgH2. Meanwhile, after complete dehydrogenation, the composites can start to absorb hydrogen below 40 °C. Compared with pure MgH2, the activation energy of hydrogen absorption and dehydrogenation of the composite decreased by 47.6 kJ/mol and 46.5 kJ/mol, respectively. In 10th cycle tests, the MgH2 + 10 wt% NiO@NiMoO4 composite still has good cycle stability. After adding a small amount of biomass charcoal, the hydrogen storage capacity can even be maintained above 97%. Furthermore, the characterization results show that the in situ generated new species Mo and Mg2Ni/Mg2NiH4 synergistically promote the adsorption and dissociation of hydrogen. This new synergistic mechanism provides new comprehensive insights for improving reversible hydrogen storage in MgH2","Meanwhile, after complete dehydrogenation, the composites can start to absorb hydrogen below 40 °C. After adding a small amount of biomass charcoal, the hydrogen storage capacity can even be maintained above 97%.",_
!006,"The 0.55LiBH4-0.45Mg(BH4)2 (LMBH) eutectic composite is promising for solid-state hydrogen storage, as it exhibits a high hydrogen capacity and a very low initial dehydrogenation temperature. However, its main hydrogen release steps still require higher temperatures. In the present study, few-layer Ti2C has been synthesized and utilized as catalysts in the LMBH. Compositing LMBH with varying amounts of Ti2C (10, 20, 30, and 40 wt%) results in low initial dehydrogenation temperatures (164–110 °C), fast desorption rates and high hydrogen capacities (7.5–10.5 wt%) at a low temperature of 260 °C. The LMBH-30Ti2C composite yields 6.5 wt% H2 even at as low as 200 °C. Additionally, the LMBH-30Ti2C composite could reversibly store 3.5 wt% H2 during the second to fourth dehydrogenation cycles without degradation. The outstanding hydrogen storage performance could be attributed to decomposition driven by reactions between high-valence Ti ions and LMBH, the in-situ formation of the active metal Ti catalyst, and the prevention of aggregation in the Ti2C-doped LMBH. © 2023 Elsevier B.V.","However, its main hydrogen release steps still require higher temperatures. Compositing LMBH with varying amounts of Ti2C (10, 20, 30, and 40 wt%) results in low initial dehydrogenation temperatures (164–110 °C), fast desorption rates and high hydrogen capacities (7.5–10.5 wt%) at a low temperature of 260 °C.",_
!007,"Magnesium hydride is one of the most sought-after materials for solid state hydrogen storage due to its low cost and high gravimetric capacity (7.6 wt% hydrogen). However, high temperature of desorption (>350 °C) and slow kinetics limit its use for commercial on-board applications. In this work, accumulative roll bonding (ARB) technique has been utilized to synthesise Mg–LaNi5–Mg2Ni-soot hybrid with enhanced hydrogen storage properties. It is seen that the hybrid absorbs ∼6.2 wt% hydrogen at a plateau pressure of ∼2 bar at 300 °C and exhibits fast kinetics with ∼6.6 wt% hydrogen absorption within ∼30 min at 300 °C and 20 bar hydrogen pressure. The role of Mg2Ni as a catalyst as well as hydrogen absorbing medium provides an effect akin to ‘hydrogen pump’, thus enhancing the rate of hydrogen absorption. Presence of carbon in various forms such as aciniform, carbonaceous microgel and cenospheres (derived from soot) plays a vital role by providing channels for diffusion of hydrogen through the hybrid. The ARB technique provides an inexpensive and scalable method of synthesis of Mg based hybrids with large number of interfaces and high amount of strain leading to enhanced hydrogen storage properties. © 2023 Hydrogen Energy Publications LLC","However, high temperature of desorption (>350 °C) and slow kinetics limit its use for commercial on-board applications. In this work, accumulative roll bonding (ARB) technique has been utilized to synthesise Mg–LaNi5–Mg2Ni-soot hybrid with enhanced hydrogen storage properties.",_
!008,"Herein, a novel approach by designing Schottky-structured CoNi nano-alloys were introduced. After compositing with MgH2, its initial hydrogen absorption started at a low temperature of 40 °C. At a temperature of 300 °C, 6.5 wt% of H2 was released in only 10 min. Furthermore, the kinetic analysis revealed a pivotal transformation in the control model for dehydrogenation of MgH2, shifted from surface penetration to diffusion at a moderate temperature of 250 °C with the introduction of CoNi-CoO@rGO. After modification, the activation energy for hydrogen de/absorption decreased from 116 kJ/mol and 79.39 kJ/mol, to 66 kJ/mol and 54.39 kJ/mol, respectively. It is noteworthy that the CoNi-CoO@rGO-modified MgH2 exhibited excellent cycling performance, retained an impressive hydrogen storage capacity of 97% after 20 cycles at 300 °C. The innovation of this work lies in the following three aspects: 1) the uniform distribution of CoNi-CoO@rGO nanoparticles on the surface of MgH2 significantly enhanced the contact area and promoted the catalytic activity, 2) the synergistic effect between Mg2Co-Mg2CoH5 and Mg2Ni-Mg2NiH4 attenuate the intensity of the Mg-H bond and quickened the post-discharge of MgH2, 3) the incorporation of a CoO-induced Schottky structure accelerated the H transfer in MgH2 and improved the hydrogen absorption and release efficiency. © 2023 Elsevier B.V.","After compositing with MgH2, its initial hydrogen absorption started at a low temperature of 40 °C. It is noteworthy that the CoNi-CoO@rGO-modified MgH2 exhibited excellent cycling performance, retained an impressive hydrogen storage capacity of 97% after 20 cycles at 300 °C.",_
!009,"Despite the promise of TiFe-based alloys as low-cost solid-state hydrogen storage materials with mild operating conditions and reasonable hydrogen capacity, their initial hydrogenation process is difficult, hindering broad utilization. The effect of alloying element on the initial hydrogenation kinetics of TiFe alloys, TiFe0.9M0.1 (M = V, Cr, Fe, Co and Ni), was evaluated by analyzing changes to the passivating surface oxide layer that inhibits hydrogen permeation, as well as the ease of initial-stage hydrogen absorption into the underlying matrix. X-ray photoelectron spectroscopy and atom probe tomography revealed key variations in surface oxide compositions and thinning of the passivating oxide layer compared to pure TiFe, which suggests suppressed oxide growth by alloying-induced elemental redistribution. At the same time, density functional theory calculations predicted exothermic formation of hydride nuclei when alloying with V or Cr, as well as a reduced nucleation barrier when alloying with Co or Ni. Overall, these results are consistent with the observed experimental trend of the activation kinetics. We propose that improvements in activation kinetics of TiFe with alloying arises from the combined effect of reduced passivating oxide thickness and easier hydride nucleation, offering a starting point for alloy design strategies towards further improvement. © 2022 The Author(s)","At the same time, density functional theory calculations predicted exothermic formation of hydride nuclei when alloying with V or Cr, as well as a reduced nucleation barrier when alloying with Co or Ni. We propose that improvements in activation kinetics of TiFe with alloying arises from the combined effect of reduced passivating oxide thickness and easier hydride nucleation, offering a starting point for alloy design strategies towards further improvement.",_
!010,"NaH and LiH are theoretically capable of storing hydrogen, but several challenges remain to be overcome before they can be widely used for hydrogen storage. In this study, LiH and NaH were ball-milled and the effect of surface area and hydrogen pressure on hydrogen storage capacity was investigated using the solid-state hydrogen storage method. XRD patterns and Raman spectra show significant shifts in main peak positions of LiH and NaH after hydrogen adsorption. BET analysis shows a significant increase in the specific surface area of LiH and NaH from 6.25 m2/g to 12.35 m2/g and from 1.34 m2/g to 2.33 m2/g respectively due to ball milling. The FTIR spectra showed more bonds in the 400–1200 cm⁻1 fingerprint region after storing hydrogen in LiH and NaH. This suggests structural changes with enhanced bond bending due to hydrogen. At 9 bar pressure, LiH and NaH exhibited excellent hydrogen storage, with ball-milled LiH reaching about 3.55 wt% and 652 sccm, and NaH achieving approximately 1.58 wt% and 291 sccm. These results highlight the significant influence of surface area and hydrogen pressure on hydrogen storage potential. Incorporating the storage potential within the evaluation of PEM fuel cell performance, we suggest that an increased storage capacity directly corresponds to an augmented power density. The analysis of power density over time revealed that the hydrogen adsorbed ball-milled LiH exhibited the highest power density, peaking at 0.075 Wcm−2 over the long term. In contrast, LiH displayed a lower power density (0.025 Wcm−2) while maintaining its long-term performance. The hydrogen adsorbed NaH and hydrogen adsorbed ball-milled NaH displayed power densities 0.050 Wcm−2 and 0.073 Wcm−2, respectively, but they showed short-term performance. © 2023 Elsevier Inc.","This suggests structural changes with enhanced bond bending due to hydrogen. In contrast, LiH displayed a lower power density (0.025 Wcm−2) while maintaining its long-term performance.",_
!011,"The first principle of calculation is a computational technique based on quantum mechanics that may precisely determine the ground-state electronic structure and associated mechanical and thermodynamic characteristics of solid materials. This study explains the history of first-principles development, calculation techniques, and the use of ultra-soft pseudopotential in hydrogen storage materials based on an inquiry and analysis of the findings of previous research. This paper primarily reviews the research progress of first principles in improving two-dimensional hydrogen storage materials, metal-organic framework materials, alkali metal-base composite hydrides, and metal-base hydrogen storage materials in order to speculate on the hydrogen storage mechanisms of materials. It is possible to estimate the location of hydrogen adsorption in a material by computing its electronic structure, band structure, electron density, and lattice vibration. This information is then used to compute the hypothetical new hydrogen storage material. Finally, the direction of first-principles computing in hydrogen storage materials is anticipated. © 2023 Hydrogen Energy Publications LLC",The first principle of calculation is a computational technique based on quantum mechanics that may precisely determine the ground-state electronic structure and associated mechanical and thermodynamic characteristics of solid materials. This information is then used to compute the hypothetical new hydrogen storage material.,_
!012,"Magnesium hydride is one of the most promising solid-state hydrogen storage materials for on-board application. Hydrogen desorption from MgH2 is accompanied by the formation of the Mg/MgH2 interfaces, which may play a key role in the further dehydrogenation process. In this work, first-principles calculations have been used to understand the dehydrogenation properties of the Mg(0001)/MgH2(110) interface. It is found that the Mg(0001)/MgH2(110) interface can weaken the Mg–H bond. The removal energies for hydrogen atoms in the interface zone are significantly lower compared to those of bulk MgH2. In terms of H mobility, hydrogen diffusion within the interface as well as into the Mg matrix is considered. The calculated energy barriers reveal that the migration of hydrogen atoms in the interface zone is easier than that in the bulk MgH2. Based on the hydrogen removal energies and diffusion barriers, we conclude that the formation of the Mg(0001)/MgH2(110) interface facilitates the dehydrogenation process of magnesium hydride. © 2024 The Authors","Magnesium hydride is one of the most promising solid-state hydrogen storage materials for on-board application. In terms of H mobility, hydrogen diffusion within the interface as well as into the Mg matrix is considered.",_
!013,"Hydrogen storage is a key link in hydrogen economy, where solid-state hydrogen storage is considered as the most promising approach because it can meet the requirement of high density and safety. Thereinto, magnesium-based materials (MgH2) are currently deemed as an attractive candidate due to the potentially high hydrogen storage density (7.6 wt%), however, the stable thermodynamics and slow kinetics limit the practical application. In this study, we design a ternary transition metal sulfide FeNi2S4 with a hollow balloon structure as a catalyst of MgH2 to address the above issues by constructing a MgH2/Mg2NiH4-MgS/Fe system. Notably, the dehydrogenation/hydrogenation of MgH2 has been significantly improved due to the synergistic catalysis of active species of Mg2Ni/Mg2NiH4, MgS and Fe originated from the MgH2-FeNi2S4 composite. The hydrogen absorption capacity of the MgH2-FeNi2S4 composite reaches to 4.02 wt% at 373 K for 1 h, a sharp contrast to the milled-MgH2 (0.67 wt%). In terms of dehydrogenation process, the initial dehydrogenation temperature of the composite is 80 K lower than that of the milled-MgH2, and the dehydrogenation activation energy decreases by 95.7 kJ·mol–1 compared with the milled-MgH2 (161.2 kJ·mol–1). This method provides a new strategy for improving the dehydrogenation/hydrogenation performance of the MgH2 material. © 2022","Hydrogen storage is a key link in hydrogen economy, where solid-state hydrogen storage is considered as the most promising approach because it can meet the requirement of high density and safety. Thereinto, magnesium-based materials (MgH2) are currently deemed as an attractive candidate due to the potentially high hydrogen storage density (7.6 wt%), however, the stable thermodynamics and slow kinetics limit the practical application.",_
!014,"Given its significant gravimetric hydrogen capacity advantage, lithium alanate (LiAlH4) is regarded as a suitable material for solid-state hydrogen storage. Nevertheless, its outrageous decomposition temperature and slow sorption kinetics hinder its application as a solid-state hydrogen storage material. This research’s objective is to investigate how the addition of titanium silicate (TiSiO4) altered the dehydrogenation behavior of LiAlH4. The LiAlH4–10 wt% TiSiO4 composite dehydrogenation temperatures were lowered to 92 °C (first-step reaction) and 128 °C (second-step reaction). According to dehydrogenation kinetic analysis, the TiSiO4-added LiAlH4 composite was able to liberate more hydrogen (about 6.0 wt%) than the undoped LiAlH4 composite (less than 1.0 wt%) at 90 °C for 2 h. After the addition of TiSiO4, the activation energies for hydrogen to liberate from LiAlH4 were lowered. Based on the Kissinger equation, the activation energies for hydrogen liberation for the two-step dehydrogenation of post-milled LiAlH4 were 103 and 115 kJ/mol, respectively. After milling LiAlH4 with 10 wt% TiSiO4, the activation energies were reduced to 68 and 77 kJ/mol, respectively. Additionally, the scanning electron microscopy images demonstrated that the LiAlH4 particles shrank and barely aggregated when 10 wt% of TiSiO4 was added. According to the X-ray diffraction results, TiSiO4 had a significant effect by lowering the decomposition temperature and increasing the rate of dehydrogenation of LiAlH4 via the new active species of AlTi and Si-containing that formed during the heating process. © 2023 by the authors.","Given its significant gravimetric hydrogen capacity advantage, lithium alanate (LiAlH4) is regarded as a suitable material for solid-state hydrogen storage. After milling LiAlH4 with 10 wt% TiSiO4, the activation energies were reduced to 68 and 77 kJ/mol, respectively.",_
!015,"The development of alloys that are hydrogenated and dehydrogenated quickly and actively at room temperature is a challenge for the safe and compact storage of hydrogen. In this study, a new high-entropy alloy (HEA) with AB-type configuration (A: hydride-forming elements, B: inert-to-hydrogen elements) was designed by considering valence electron concentration, electronegativity difference and atomic-size mismatch of elements. The alloy TiV2ZrCrMnFeNi had dual C14 Laves and BCC phases, in which C14 stored hydrogen and BCC/C14 interphase boundaries contributed to activation. The alloy absorbed 1.6 wt% of hydrogen at room temperature without any activation treatment and exhibited fast kinetics and full reversibility. © 2023 Acta Materialia Inc.","In this study, a new high-entropy alloy (HEA) with AB-type configuration (A: hydride-forming elements, B: inert-to-hydrogen elements) was designed by considering valence electron concentration, electronegativity difference and atomic-size mismatch of elements. The alloy absorbed 1.6 wt% of hydrogen at room temperature without any activation treatment and exhibited fast kinetics and full reversibility.",_
!016,"The metal-hydrogen interaction and its equilibrium conditions allow for distinct properties in metal hydrides (MHs). Based on these properties, MHs have been found to enable a range of novel technologies from thermal compression to sensors, and catalysis. Ni-MH batteries are currently the main application of hydrides in the market. However, new battery concepts such as Li-MgH2, Mn-MH, and hydride-based solid electrolytes have emerged. Fuel cells based on hydrides have also been proposed to convert the chemical “hydride energy” into electrical energy. Based on their unique thermodynamic properties, MHs are also the basis of new concepts in hydrogen compression, heat pumps, cooling systems, and thermal energy storage. Other important applications, including catalysis and chemical speciation have also been considered owing the chemical properties of hydrides. Sensors and smart mirrors based on the dynamic optical, structural, and electrical properties of MHs have been developed. This review summarizes current state-of-the-art along the multiple applications of MHs and provides recommendations on the future progress required to enable a more widespread adoption of MHs beyond their use as hydrogen storage materials. © 2022 Elsevier B.V.","The metal-hydrogen interaction and its equilibrium conditions allow for distinct properties in metal hydrides (MHs). Based on their unique thermodynamic properties, MHs are also the basis of new concepts in hydrogen compression, heat pumps, cooling systems, and thermal energy storage.",_
!017,"Solid state hydrogen storage addresses the problems of high pressurization in compressed gaseous state and energy intensive liquefaction in liquid state. Clathrate structures have shown promising results as host material for storing hydrogen as hydrate. The effect of different promoters on improving storage capabilities of clathrates have been studied at 263 K and 10 MPa hydrogen pressure. Hydrogen adsorption kinetics of four different clathrates using promoters Tetrahydrofuran, Tetrahydropyran, 1,3 Dioxolane and 2,3 Dihydrofuran with Multiwall Carbon nanotube as substrate was carried out. The results showed ∼1.5 wt% hydrogen adsorption within 90 min using CNT substrate. This is one of the first reports on usage of CNT as a substrate material for hydrogen storage in clathrate systems. It was observed that CNT shows synergitic effect in the hydrogen adsorption with fast kinetics (less than 90 min). The weight of substrate material (CNT) was also taken into consideration while calculating the weight % of hydrogen adsorption. The present study also involves design and simulation of a hydrogen storage canister (using CNT based clathrate) with embedded helical coolant coils on COMSOL Multiphysics software to analyse the effects of temperature management on improving hydrogen storage capability of the clathrate reactor bed. Results of simulation includes variation of hydrate concentration and temperature in clathrate reactor bed with the passage of time. The theoretical studies pave way for validating the scalability of clatharates as a viable hydrogen energy system. © 2022 Hydrogen Energy Publications LLC","Hydrogen adsorption kinetics of four different clathrates using promoters Tetrahydrofuran, Tetrahydropyran, 1,3 Dioxolane and 2,3 Dihydrofuran with Multiwall Carbon nanotube as substrate was carried out. It was observed that CNT shows synergitic effect in the hydrogen adsorption with fast kinetics (less than 90 min).",_
!018,"The increasing energy demand and the worldwide energy crisis must be met in large part via the sustainable growth of hydrogen energy, since this economy is relied upon to provide clean and carbon-free energy carriers. It is anticipated that the growing demand for light and heavy fuel cell cars would stimulate the development of onboard solid-state hydrogen technology. The research here concentrates on the importance of various permeable substances such as polymers in general, metallic substances, and complex metal hydrides, even if Si nanostructures (SiNSs) have become known as the obvious contender for solid-state hydrogen storage systems. SiNSs have gained prominence as a leading candidate for solid-state hydrogen storage systems. Renowned for their high storage capacity, SiNSs, including silicon nanowires and quantum dots, exhibit promising potential in addressing challenges associated with traditional hydrogen storage methods, positioning them as a key player in advancing clean and efficient energy storage technologies. SiNSs play a crucial role in advancing solid-state hydrogen storage technology. SiNSs, including silicon nanowires and quantum dots, exhibit high storage capacity. Despite challenges like surface oxidation, SiNS holds promise for efficient hydrogen storage, contributing to the development of sustainable energy solutions and mitigating the environmental impact associated with conventional automotive technologies. We focus on the processes that result in permeable silicon, nanowires made of porous silicon, and Si quantum dots. This investigation elucidates the characteristics and patterns of hydrogen's aid, the value of hydrogen power in automobiles for reducing global warming occurrences, and the potential of using SiNSs for hydrogen storage in tandem with other forms of transition and alkali earth materials to meet these difficulties. It demonstrates how catalysts are critical to fixing the current reversibility and desorption problems with hydrogen energy storage. As a result of the analysis, energy suppliers and Si-based fuel cells may be better able to tailor their services to individual customers' needs, which might boost the growth of the hydrogen energy industry. © 2024 Elsevier Ltd",SiNSs have gained prominence as a leading candidate for solid-state hydrogen storage systems. It demonstrates how catalysts are critical to fixing the current reversibility and desorption problems with hydrogen energy storage.,_
!019,"Hydrogen plays a crucial role in the future energy landscape owing to its high energy density. However, finding an ideal storage material is the key challenge to the success of the hydrogen economy. Various solid-state hydrogen storage materials, such as metal hydrides, have been developed to realize safe, effective, and compact hydrogen storage. However, low kinetics and thermodynamic stability lead to a high working temperature and a low hydrogen sorption rate of the metal hydrides. Using scaffolds made from porous materials like silica to confine the metal hydrides is necessary for better and improved hydrogen storage. Therefore, this article reviews porous silica-based scaffolds as an ideal material for improved hydrogen storage. The outcome showed that confining the metal hydrides using scaffolds based on porous silica significantly increases their storage capacities. It was also found that the structural modifications of the silica-based scaffold into a hollow structure further improved the storage capacity and increased the affinity and confinement ability of the metal hydrides, which prevents the agglomeration of metal particles during the adsorption/desorption process. Hence, the structural modifications of the silica material into a fibrous and hollow material are recommended to be crucial for further enhancing the metal hydride storage capacity. © 2023 Wiley-VCH GmbH.","Using scaffolds made from porous materials like silica to confine the metal hydrides is necessary for better and improved hydrogen storage. Therefore, this article reviews porous silica-based scaffolds as an ideal material for improved hydrogen storage.",_
!020,"This study describes the hydrogen storage performance of NaAlH4 with the addition of CuFe2O4 additive. The results were compared with undoped NaAlH4. For the first and second steps of dehydrogenation, the CuFe2O4-doped NaAlH4 liberated hydrogen at 150 °C and 220 °C, whereas as-milled NaAlH4 released hydrogen at 190 °C and 290 °C, respectively. The desorption kinetic analysis unveiled that the doped system liberated around 1.5 and 4.4 wt% hydrogen within 120 min at 150 and 200 °C, respectively. Meanwhile, the undoped NaAlH4 only desorbed 0.5 and 3.6 wt% hydrogen, respectively, under identical conditions. The activation energy for the doped system at the first step of dehydrogenation was decreased from 114.7 to 92.5 kJ/mol, while reduced from 125.2 to 98.1 kJ/mol at the second stage. The synergistic impact between the in-situ formed Cu2O and Fe during the heating process indicated that these active species are superior in boosting the hydrogen storage performance of NaAlH4. © 2023 Hydrogen Energy Publications LLC","The desorption kinetic analysis unveiled that the doped system liberated around 1.5 and 4.4 wt% hydrogen within 120 min at 150 and 200 °C, respectively. Meanwhile, the undoped NaAlH4 only desorbed 0.5 and 3.6 wt% hydrogen, respectively, under identical conditions.",_
!021,"The growing demand for energy and the need to reduce the carbon footprint has made green hydrogen a promising alternative to traditional fossil fuels. Green hydrogen is produced using renewable energy sources, making it a sustainable and environmentally friendly energy source. Solid-state hydrogen storage aims to store hydrogen in a solid matrix, offering potential advantages such as higher safety and improved energy density compared to traditional storage methods such as compressed gas or liquid hydrogen. However, the development of efficient and economically viable solid-state storage materials is still a challenge, and research continues in this field. Borophene is a two-dimensional material that offers potential as an intermediate hydrogen storage material due to its moderate binding energy and reversible behavior. Its unique geometry and electronic properties also allow for higher hydrogen adsorption capacity than metal-based complex hydrides, surpassing the goals set by the U.S. Department of Energy. Borophene has shown great potential for hydrogen storage, but it is still not practical for commercial use. In this review, borophene nanomaterials chemical and physical properties are discussed, related to hydrogen storage and binding energy. The importance of borophene for hydrogen storage, the challenges it faces, and its future prospects are also being discussed. © 2023 The Author(s)","Borophene is a two-dimensional material that offers potential as an intermediate hydrogen storage material due to its moderate binding energy and reversible behavior. Its unique geometry and electronic properties also allow for higher hydrogen adsorption capacity than metal-based complex hydrides, surpassing the goals set by the U.S. Department of Energy.",_
!022,"Magnesium hydride is considered as a promising solid-state hydrogen storage material due to its high hydrogen capacity. How to improve hydrogen desorption kinetics of MgH2 is one of key issues for its practical applications. In this study, we synthesize a Mg–Ni–TiS2 composite through a solution-based synthetic strategy. In the as-prepared composite, the co-precipitated Mg and Ni nanoparticles are highly dispersed on TiS2 nanosheets. As a result, the activation energy for hydrogen desorption decreases to 79.4 kJ mol−1. Meanwhile, the capacity retention rate is kept at the level of 98% and only slight kinetic deterioration is caused after fifty hydrogenation-dehydrogenation cycles. Further investigation indicates that the superior hydrogen desorption kinetics is attributed to the synergistically catalytic effect of the in situ formed Mg2NiH4 and TiH2, and the remained TiS2. The excellent cycle stability is related not only to the inhibition effect of the secondary phases on powder agglomeration and crystallite growth of Mg and MgH2 but also to the prevention effect of MgS and TiS2 on redistribution of catalytic Mg2NiH4 and TiH2 nanoparticles during cycling. This work introduces a feasible approach to develop Mg-based hydrogen storage materials. © 2023 Hydrogen Energy Publications LLC","As a result, the activation energy for hydrogen desorption decreases to 79.4 kJ mol−1. This work introduces a feasible approach to develop Mg-based hydrogen storage materials.",_
!023,"For hydrogen to be successfully used as an energy carrier in a new renewable energy driven economy, more efficient hydrogen storage technologies have to be found. Solid-state hydrogen storage in complex metal hydrides, such as sodium alanate (NaAlH4), is a well-researched candidate for this application. A series of NaAlH4/mesoporous carbon black composites, with high NaAlH4 content (50–90 wt%), prepared via ball milling have demonstrated significantly lower dehydrogenation temperatures with intense dehydrogenation starting at ∼373 K compared to bulk alanate's ≥ 456 K. Dehydrogenation/hydrogenation cycling experiments have demonstrated partial hydrogenation at 6 MPa H2 and 423 K. The cycling experiments combined with temperature-programmed dehydrogenation and powder X-ray diffraction have given insight into the fundamental processes driving the H2 release and uptake in the NaAlH4/carbon composites. It is established that most of the hydrogenation behavior can be attributed to the Na3AlH6 ↔ NaH transition. © 2023 The Authors","Solid-state hydrogen storage in complex metal hydrides, such as sodium alanate (NaAlH4), is a well-researched candidate for this application. A series of NaAlH4/mesoporous carbon black composites, with high NaAlH4 content (50–90 wt%), prepared via ball milling have demonstrated significantly lower dehydrogenation temperatures with intense dehydrogenation starting at ∼373 K compared to bulk alanate's ≥ 456 K. Dehydrogenation/hydrogenation cycling experiments have demonstrated partial hydrogenation at 6 MPa H2 and 423 K. The cycling experiments combined with temperature-programmed dehydrogenation and powder X-ray diffraction have given insight into the fundamental processes driving the H2 release and uptake in the NaAlH4/carbon composites.",_
!024,"Hypothesis: With increased development and electricity generation, great care to energy storage systems is crucial to overcome the discontinuity in the renewable production. Hydrogen is an ideal energy carrier for near future mobility, like automotive applications. Solid-state hydrogen storage materials including nanomaterials and layered systems are the key enablers to the future energy needs. However, the current materials are unable to meet all requirements in the storage capacity and commercialization. The hydrogen storage mechanisms (physical and chemical) are the key-points addressing the shortcomings in hydrogen absorption/adsorption in the interlayer space or on the surface of the material. All above require strategy for designing new hydrogen storage materials. Experiments: This review lays the recent foundations in the materials suitable for hydrogen storage particularly alloys, mixed metal oxides (MMOs), and their respective nanocomposites. Alloys and MMOs are two classes of materials with high discharge capacities, appropriate electrochemical performances, chemical stability, easy production pathways, and almost low cost. In the same vein, highly porous materials with a large surface area such as metal organic frameworks (MOFs), MXenes and carbon materials are thermodynamically and kinetically more favorable. Findings: The literature review illustrates that it is crucial to develop new materials with large-surface area, homogeneous texture, active-conductive profiles, large oxygen vacancies and low-cost. Multiphase materials (nanocomposites/hybrids) composed of at least two of above-mentioned materials can meet the established requirements in this field. Also, the present paper demonstrates a general overview of promoted understanding of hydrogen storage mechanisms on alloy/MMOs-based compounds in the energy storage systems. It is hoped that these observations pave the potential exploration directions to dominate imminent challenges in solid-state hydrogen storage. © 2023 Elsevier Ltd","Findings: The literature review illustrates that it is crucial to develop new materials with large-surface area, homogeneous texture, active-conductive profiles, large oxygen vacancies and low-cost. It is hoped that these observations pave the potential exploration directions to dominate imminent challenges in solid-state hydrogen storage.",_
!025,"As global energy consumption is rapidly climbing to maximum, fossil fuel resources face depletion on a global scale. The rapid depletion and higher energy demand consequences an escalation of energy prices originating from conventional sources as well as the release of greenhouse gases into the environment. Hydrogen as an alternative energy source merged as an ideal candidate, distinguished by its remarkable attributes and manifold advantages. It has an exceptional energy density of 120 MJ/kg and encompasses non-toxicity, sustainability, and a favorable environmental profile. Renewable and non-renewable sources can produce hydrogen and have versatile applications in transportation, power generation via fuel cells, and other industrial processes. Beyond having these advantages hydrogen has the benefits of energy security and can be produced locally. Nevertheless, commercial hydrogen has exceptionally low volumetric density under standard conditions which is the major obstacle in the way of its development. To cater this issue and to enhance its economic feasibility, two well-established methodologies are used by alterations in temperature and/or pressure conditions which facilitate the storage of hydrogen either in a pressurized gas or a cryogenic liquid. However, both methods incur energy consumption and pose safety concerns and complexity in the system, which raises the question of having other storage solutions. An emerging technology based on Solid-state hydrogen storage systems has recently gained substantial attention because of its high storage capacity and relatively mild temperature and pressure requirements. However, this technology is not yet mature enough because it doesn't fulfil the requirements to be implemented for industrial applications. But, intensive research in this field is underway to develop novel materials with enhanced performance at both the material and the system level. The current review report is focused on a comprehensive and in-depth comparative analysis of various hydrogen storage methods, with a major focus on the enhancement of the performance of the material which is suitable for solid-state hydrogen storage applications. © 2023 Hydrogen Energy Publications LLC","Beyond having these advantages hydrogen has the benefits of energy security and can be produced locally. However, this technology is not yet mature enough because it doesn't fulfil the requirements to be implemented for industrial applications.",_
!026,"Exceptionally porous crystals with ultrahigh adsorption capacities, metal–organic frameworks (MOFs), have received recognition as leading candidates for the promotion of solid-state hydrogen storage. MOFs are compelling adsorbents given their impressive uptake under stringent cryogenic and high-pressure conditions for physisorption. The use of high-throughput screening to rapidly identify potential candidates, the understanding of structure–property correlations through molecular simulations, and the use of machine learning to predict material properties offer a more efficient approach to meeting these stringent operational constraints. Furthermore, the open metal sites and customizable pore structures act make MOFs as catalysts or nanoconfinement matrices, facilitating enhancements in the thermodynamics and kinetics of reactive chemical hydrides. Strategically harnessing the tunability of MOFs could unlock vast, untapped potential for enabling high-density, reversible hydrogen storage under real-world conditions, aligned with sustainability needs. This review establishes MOFs as an innovative platform in solid-state hydrogen storage by intertwining material discovery with engineering principles. The comprehensive analysis and consolidation of the research provides new perspectives to broaden the scope of the investigation and drive the widespread deployment and development of hydrogen energy. © 2024 Elsevier B.V.","Exceptionally porous crystals with ultrahigh adsorption capacities, metal–organic frameworks (MOFs), have received recognition as leading candidates for the promotion of solid-state hydrogen storage. Strategically harnessing the tunability of MOFs could unlock vast, untapped potential for enabling high-density, reversible hydrogen storage under real-world conditions, aligned with sustainability needs.",_
!027,"Hydrogen is regarded as one of the most promising energy sources of the future, due to its low-cost, zero-pollution, and high-heat value. Nevertheless, traditional methods of storing hydrogen are commonly accompanied by the risk of leaks and explosions, so how to store and transport hydrogen safely and efficiently is a critical issue that needs to be addressed. Solid-state hydrogen storage is the most attractive way to store hydrogen in nanomaterials by chemical or physical adsorption, which has the advantages of high energy density and good safety. Here, a rational Ni-Zn bimetallic MOF has been constructed by a straightforward synthetic technique, in which the Zn atom was partially replaced by the Ni atom. The micropore rate of the Ni-Zn bimetallic MOFs is higher than that of ZIF-8. In addition, the presence of Ni provides more unsaturated metal sites and strengthens the bonding between hydrogen molecules and Ni, effectively improving the hydrogen storage capacity of Ni-Zn bimetallic MOFs. The experimental results show that the hydrogen adsorption capacity of Ni-Zn bimetallic MOFs can reach 1.35 wt% at 77 K and 1 bar. © 2023 The Royal Society of Chemistry.","Solid-state hydrogen storage is the most attractive way to store hydrogen in nanomaterials by chemical or physical adsorption, which has the advantages of high energy density and good safety. Here, a rational Ni-Zn bimetallic MOF has been constructed by a straightforward synthetic technique, in which the Zn atom was partially replaced by the Ni atom.",_
!028,"Hydrazine borane (N2H4BH3) has attracted considerable interest as a promising solid-state hydrogen storage material owing to its high hydrogen content and easy preparation. In this work, pressure-induced phase transitions of N2H4BH3 were investigated using a combination of vibrational spectroscopy, X-ray diffraction, and density functional theory (DFT) up to 30 GPa. Our results showed that N2H4BH3 exhibits remarkable structural stability in a very broad pressure region up to 15 GPa, and then two phase transitions were identified: the first one is from the ambient-pressure Pbcn phase to a Pbca phase near 15 GPa; the second is from the Pbca phase to a Pccn phase near 25 GPa. As revealed by DFT calculations, the unusual stability of N2H4BH3 and the late phase transformations were attributed to the pressure-mediated evolutions of dihydrogen bonding frameworks, the compressibility and the enthalpies of the high-pressure polymorphs. Our findings provide new insight into the structures and bonding properties of N2H4BH3 that are important for hydrogen storage applications. © 2023 The Royal Society of Chemistry.","In this work, pressure-induced phase transitions of N2H4BH3 were investigated using a combination of vibrational spectroscopy, X-ray diffraction, and density functional theory (DFT) up to 30 GPa. Our findings provide new insight into the structures and bonding properties of N2H4BH3 that are important for hydrogen storage applications.",_
!029,"Magnesium hydride has great potential for solid-state hydrogen storage. However, high dehydrogenation temperature and sluggish hydrogen absorption and desorption kinetics restrict its on-board automotive application. Hydrogen desorption from MgH2 is accompanied by the formation of Mg/MgH2 interfaces, which may play a key role in the further dehydrogenation process. In this work, first principles methods were used to understand the structural, electronic, energetic and hydrogen diffusion kinetic properties of pure and Ti-doped Mg(0001)/MgH2(110) interfaces. It is found that Ti interface doping can slightly increase the interfacial stability as revealed by the work of adhesion, interface energy and electronic structure. Additionally, for both the pure and Ti-doped Mg(0001)/MgH2(110) interfaces, the removal energies for the H atoms in the interface zone are significantly low compared with that of bulk MgH2. In terms of H mobility, the Ti dopant is beneficial for H atoms migrating from the inner layers to the interface for aggregation. Furthermore, hydrogen desorption from the two interfaces mainly takes place by hydrogen diffusion within the interface rather than across the interface into the Mg matrix, and Ti doping can enhance this process significantly. These theoretical observations for hydrogen diffusion behavior at the interface are further validated by fitting the isothermal dehydrogenation curves of MgH2-Ti with a series of kinetic models. © 2023 The Royal Society of Chemistry.","It is found that Ti interface doping can slightly increase the interfacial stability as revealed by the work of adhesion, interface energy and electronic structure. These theoretical observations for hydrogen diffusion behavior at the interface are further validated by fitting the isothermal dehydrogenation curves of MgH2-Ti with a series of kinetic models.",_
!030,"MgH2, a solid-state hydrogen storage material with high storage capacity, is facing the obstacles of high thermodynamic stability and slow reaction kinetics. Herein, different Vanadium (V) based catalysts (V2O5, Fe–V and V–Ni oxides) were synthesized by a hydrothermal method and ball milled with MgH2 to modify its hydrogen storage property. It is observed that the dehydrogenation performance (initial dehydrogenation temperature and desorption rate) of Fe–V oxide doped MgH2 was the best, followed by V2O5 and V–Ni oxide modified systems. The MgH2+7 wt% Fe–V composite exhibited an onset dehydrogenation temperature of 200 °C, 128 °C lower compared with the original MgH2. The absorption performance of MgH2 was also greatly enhanced by Fe–V oxide. The 7 wt% Fe–V modified MgH2 after dehydrogenation began to charge hydrogen from 25 °C to 5.1 wt% hydrogen was absorbed at 150 °C. The activation energy for hydrogen uptake of MgH2 was reduced from 76.5 ± 3.4 kJ/mol to 41.2 ± 4.7 kJ/mol. Additionally, the MgH2+7 wt% Fe–V composite maintained 97.2% hydrogen capacity after10 cycles. Our work here proves that elements substitution is a feasible way to tune the catalytic effect of oxides and may shed light on designing catalysts with higher activation in the future. © 2022 Elsevier Ltd",The activation energy for hydrogen uptake of MgH2 was reduced from 76.5 ± 3.4 kJ/mol to 41.2 ± 4.7 kJ/mol. Our work here proves that elements substitution is a feasible way to tune the catalytic effect of oxides and may shed light on designing catalysts with higher activation in the future.,_
!031,"In the burgeoning field of hydrogen energy, compositionally complex alloys promise unprecedented solid-state hydrogen storage applications. However, compositionally complex alloys are facing one main challenge: reducing alloy density and increasing hydrogen storage capacity. Here, we report TiMgLi-based compositionally complex alloys with ultralow alloy density and significant room-temperature hydrogen storage capacity. The record-low alloy density (2.83 g cm−3) is made possible by multi-principal-lightweight element alloying. Introducing multiple phases instead of a single phase facilitates obtaining a large hydrogen storage capacity (2.62 wt% at 50 °C under 100 bar of H2). The kinetic modeling results indicate that three-dimensional diffusion governs the hydrogenation reaction of the current compositionally complex alloys at 50 °C. The here proposed approach broadens the horizon for designing lightweight compositionally complex alloys for hydrogen storage purposes. © 2023 Elsevier Ltd","However, compositionally complex alloys are facing one main challenge: reducing alloy density and increasing hydrogen storage capacity. Here, we report TiMgLi-based compositionally complex alloys with ultralow alloy density and significant room-temperature hydrogen storage capacity.",_
!032,"Solid-state hydrogen storage is a promising roadmap for the safe and efficient utilization of hydrogen energy due to its moderate operating environment and high hydrogen storage density. However, as a representative solid-state hydrogen storage material, magnesium hydride (MgH2) is significantly limited in the commercial application due to its sluggish kinetics in the dehydrogenation process. Single-atom catalysts are a promising solution to this dilemma. However, the promising graphene-based single-atom catalysts are not yet sufficient to meet the dehydrogenation needs in engineering. To further address this dilemma, we designed a novel γ-graphyne based single-atom catalysts including eight 3d transition metals for promoting the dehydrogenation process of MgH2. Through using spin-polarized density functional theory calculations, we found that the energy barrier for MgH2 dehydrogenation has been significantly reduced even to 0.70 eV, which is far lower than the current graphene-based single-atom catalyst. In detail, the migration trajectory of hydrogen atom in the dehydrogenation process has been observed and confirmed using the ab initio molecular dynamics simulations. To investigate the intrinsic origin for its high catalytic activity of single-atom catalyst, we analyze the H[sbnd]Mg bond activation mechanism through the electron localization function, charge density difference and crystal orbital Hamiltonian population. Finally, we found the relationship between energy barrier with electronic structure of single-atom catalyst, such as electrostatic potential and system electronegativity. This work can not only provide new ideas for the optimize of dehydrogenation catalyst, but also lay a theoretical foundation for the design of novel energy storage material. © 2023 Elsevier Ltd","To further address this dilemma, we designed a novel γ-graphyne based single-atom catalysts including eight 3d transition metals for promoting the dehydrogenation process of MgH2. Finally, we found the relationship between energy barrier with electronic structure of single-atom catalyst, such as electrostatic potential and system electronegativity.",_
!033,"Researchers have focused on nanostructure materials in the last decade, which can play an essential role in storing hydrogen gas. Hydrogen is a future source of energy, having handling and storage challenges. In the new generation, solid-state materials have been used to store hydrogen gas as a metal hydride. Based on materials properties, Mg hydride is the most promising material to store hydrogen in a solid-state material. The theoretical hydrogen storage capacity of magnesium hydride is 7.6 wt% making it a more suitable material for hydrogen storage in the future. Instead of having high storage capacity, magnesium's practical application as a hydride is limited due to its low kinetics and high working temperature. Aside from the less thermo-stability of bulk MgH2, to achieve the maximum hydrogen storage capacity the decomposition required a higher temperature of about 300 °C with 1 bar pressure. As a result, it is necessary to optimize the stability of hydrogen and magnesium molecules to enhance kinetic and thermodynamic properties. The critical factors in improving hydrogenation properties are decreasing particle size (nano-scale) and adding various catalysts. © 2023 Elsevier Ltd. All rights reserved.","In the new generation, solid-state materials have been used to store hydrogen gas as a metal hydride. The critical factors in improving hydrogenation properties are decreasing particle size (nano-scale) and adding various catalysts.",_
!034,"In this study, structural, mechanical, electronic, dynamic, thermodynamic and hydrogen storage properties of MgX3H8 (X = Sc, Ti, Zr) were investigated by means of density functional theory which was not studied/reported experimentally or theoretically in the previous literature. This is the first thorough study about various properties of these materials. These materials were considered as promising potential host materials for solid state hydrogen storage. The evaluation of computed formation enthalpies of MgX3H8 (X = Sc, Ti, Zr), elastic constants, and phonon dispersion graphs revealed that MgX3H8 (X = Sc, Ti, Zr) is thermodynamically, mechanically, and dynamically stable and synthesizable. The analysis of B/G ratio, Cp and Poisson's ratio showed that MgSc3H8 is a brittle material whereas MgTi3H8 and MgZr3H8 are ductile materials. Moreover, anisotropy factor, machinability index, hardness, melting and Debye temperature of the materials were obtained and analysed in depth. The electronic band structures of MgX3H8 (X = Sc, Ti, Zr) illustrated metallic character since the bands (valence and conduction) intersect the Fermi level along the main symmetry directions. The phonon dispersion curves, and the partial state densities of the materials have positive frequencies, therefore, materials are dynamically stable in the cubic structure. The gravimetric hydrogen densities were calculated as 4.60 wt% for MgSc3H8, 4.38 wt% for MgTi3H8 and 2.56 wt% for MgZr3H8. The hydrogen desorption temperatures were computed as 239.54 K for MgSc3H8, 241.76 K for MgTi3H8 and 303.87 K for MgZr3H8. The mechanical properties of the materials suggest that they can be promising host materials for hydrogen storage. © 2024 Elsevier Ltd","In this study, structural, mechanical, electronic, dynamic, thermodynamic and hydrogen storage properties of MgX3H8 (X = Sc, Ti, Zr) were investigated by means of density functional theory which was not studied/reported experimentally or theoretically in the previous literature. This is the first thorough study about various properties of these materials.",_
!035,"Solid-state hydrogen storage materials are safe and lightweight hydrogen carriers. Among the various solid-state hydrogen carriers, hydrogen boride (HB) sheets possess a high gravimetric hydrogen capacity (8.5 wt%). However, heating at high temperatures and/or strong ultraviolet illumination is required to release hydrogen (H2) from HB sheets. In this study, the electrochemical H2 release from HB sheets using a dispersion system in an organic solvent without other proton sources is investigated. H2 molecules are released from the HB sheets under the application of a cathodic potential. The Faradaic efficiency for H2 release from HB sheets reached >90%, and the onset potential for H2 release is −0.445 V versus Ag/Ag+, which is more positive than those from other proton sources, such as water or formic acid, under the same electrochemical conditions. The total electrochemically released H2 in a long-time experiment reached ≈100% of the hydrogen capacity of HB sheets. The H2 release from HB sheets is driven by a small bias; thus, they can be applied as safe and lightweight hydrogen carriers with economical hydrogen release properties. © 2024 The Authors. Small published by Wiley-VCH GmbH.","However, heating at high temperatures and/or strong ultraviolet illumination is required to release hydrogen (H2) from HB sheets. The H2 release from HB sheets is driven by a small bias; thus, they can be applied as safe and lightweight hydrogen carriers with economical hydrogen release properties.",_
!036,"Lithium is a popular lightweight material in the field of energy storage because of its hydrogen-binding properties and electrochemical advantages. The high hydrogen uptake capacity (∼12.6 wt%) of lithium hydride (LiH) is limited by the major thermodynamic constraint of requiring a higher temperature (∼700 °C) for desorption at 0.1 MPa. Incorporating a third element that creates Li phases during LiH dehydrogenation can help overcome thermodynamic constraints. This study involves modifying the hydrogen storage properties and thermodynamic characteristics of LiH through mechanical alloying with porous silicon (PS). Pressure composition isotherms measure the reversible hydrogen storage capacity (∼3.39 wt%) of LiH-PS alloy at different temperatures. The energy of hydrogen interaction is quantified by isosteric heat of absorption, which provides the enthalpy change in the reaction system. Hydrogen absorption and desorption enthalpies of 94.5 kJ (mol H2)−1 and 114.9 kJ (mol H2)−1 demonstrate the lowest energy demand among previously reported LiH alloys. The energy of hydrogen interaction is quantified by isosteric heat of absorption, which provides the enthalpy change in the reaction system. The hydride decomposition of the alloy indicates the possible range of hydrogen desorption. © 2023 Hydrogen Energy Publications LLC",This study involves modifying the hydrogen storage properties and thermodynamic characteristics of LiH through mechanical alloying with porous silicon (PS). Pressure composition isotherms measure the reversible hydrogen storage capacity (∼3.39 wt%) of LiH-PS alloy at different temperatures.,_
!037,"This investigation explores the solid-state hydrogen storage properties of two series of hydrogen storage alloys: (Ti0.85Zr0.15)xMn0.8CrFe0.2 (x = 1.00∼1.10) and (Ti0.85Zr0.15)1.02MnyCr1.8-yFe0.2 (y = 1.00∼0.40) alloys. These alloys exhibit a single C14-Laves phase structure and demonstrate promising capabilities for solid-state hydrogen storage. The (Ti0.85Zr0.15)xMn0.8CrFe0.2 (x = 1.00∼1.10) alloys display an increased hydrogen absorption capacity and a reduced plateau pressure at higher super-stoichiometric ratios of x. When x = 1.10, the alloy achieves a maximum capacity of 1.86 wt%. The hydrogen storage capacity of the (Ti0.85Zr0.15)1.02MnyCr1.8-yFe0.2 (y = 1.00∼0.40) alloys diminishes as the value of y decreases. Furthermore, the hydrogen absorption plateau pressure and hysteresis factor of the alloys increase with an escalating Mn/Cr ratio. The analysis of cyclic stability reveals that the primary factor contributing to poor cycling stability of the (Ti0.85Zr0.15)1.02Mn0.4Cr1.4Fe0.2 alloy is the compositional decomposition, rather than pulverization or alterations in the phase structure. In summary, this investigation enhances our understanding of the solid-state hydrogen storage properties of these alloys. It establishes a foundation for further research and development in this pivotal field of hydrogen storage. © 2023 Hydrogen Energy Publications LLC",These alloys exhibit a single C14-Laves phase structure and demonstrate promising capabilities for solid-state hydrogen storage. It establishes a foundation for further research and development in this pivotal field of hydrogen storage.,_
!038,"Hydrogen storage and transportation technology is the key part that affects the large-scale and commercial application of hydrogen energy, and it is also an important factor that influences the future development pattern of the world clean energy industry. Compared with several current hydrogen storage and transportation technologies, solid-state hydrogen storage technology plays an important role in the field of hydrogen storage and transportation with its high quality density and high safety. Starting from the principles of hydrogen storage based on chemical adsorption mechanism, the research progress and status quo of different solid-state hydrogen storage materials are introduced. From the perspective of raw materials, technology maturity, research projects and the number of patents, the development prospect of solid-state hydrogen storage technology in the future is analyzed. © 2023 Editorial Office of P.R.E.. All rights reserved.","Compared with several current hydrogen storage and transportation technologies, solid-state hydrogen storage technology plays an important role in the field of hydrogen storage and transportation with its high quality density and high safety. Starting from the principles of hydrogen storage based on chemical adsorption mechanism, the research progress and status quo of different solid-state hydrogen storage materials are introduced.",_
!039,"Solid-state hydrogen storage is gradually becoming an effective way for the large-scale storage and transportation of hydrogen energy. Magnesium hydride (MgH2) has become a promising candidate among solid-state hydrogen storage materials due to its high hydrogen storage density, low cost and good safety. However, ambiguous H-Mg bond weakening mechanism of various catalysts on MgH2 hinders the development of novel catalysts for MgH2 dehydrogenation. To overcome this problem, we applied the model catalyst, single-atom catalyst with accurately characterizable coordination structure, to understand the interaction between catalyst and MgH2 surface through spin-polarized density-functional theory calculation. We constructed heterogeneous interface structures between single-atom catalysts and MgH2 surface including nine kinds of transition metal atoms. The interaction between single-atom catalysts and MgH2 surface has been well explored through bond length, electron localization function, charge density difference and crystal orbital Hamiltonian population, providing the intrinsic information of H-Mg bond weakening mechanism over single-atom catalysts. This work can establish the foundational guide for the design of novel dehydrogenation catalysts. © 2024, The Author(s).","We constructed heterogeneous interface structures between single-atom catalysts and MgH2 surface including nine kinds of transition metal atoms. The interaction between single-atom catalysts and MgH2 surface has been well explored through bond length, electron localization function, charge density difference and crystal orbital Hamiltonian population, providing the intrinsic information of H-Mg bond weakening mechanism over single-atom catalysts.",_
!040,"In the process of building a new power system with new energy sources as the mainstay, wind power and photovoltaic energy enter the multiplication stage with randomness and uncertainty, and the foundation and support role of large-scale long-time energy storage is highlighted. Considering the advantages of hydrogen energy storage in large-scale, cross-seasonal and cross-regional aspects, the necessity, feasibility and economy of hydrogen energy participation in long-time energy storage under the new power system are discussed. Firstly, power supply and demand production simulations were carried out based on the characteristics of new energy generation in China. When the penetration of new energy sources in the new power system reaches 45%, long-term energy storage becomes an essential regulation tool. Secondly, by comparing the storage duration, storage scale and application scenarios of various energy storage technologies, it was determined that hydrogen storage is the most preferable choice to participate in large-scale and long-term energy storage. Three long-time hydrogen storage methods are screened out from numerous hydrogen storage technologies, including salt-cavern hydrogen storage, natural gas blending and solid-state hydrogen storage. Finally, by analyzing the development status and economy of the above three types of hydrogen storage technologies, and based on the geographical characteristics and resource endowment of China, it is pointed out that China will form a hydrogen storage system of “solid state hydrogen storage above ground and salt cavern storage underground” in the future. © 2023 by the authors.","Firstly, power supply and demand production simulations were carried out based on the characteristics of new energy generation in China. Finally, by analyzing the development status and economy of the above three types of hydrogen storage technologies, and based on the geographical characteristics and resource endowment of China, it is pointed out that China will form a hydrogen storage system of “solid state hydrogen storage above ground and salt cavern storage underground” in the future.",_
!041,"Recently, high entropy alloys (HEAs) with body-centred cubic (BCC) single phase structures have attracted wide attention in many fields including hydrogen storage, due to their unique structural characteristics and excellent performance. Its novel design concept provides more possibilities for the investigation of advanced hydrogen storage materials, in which several remarkable research works have been published, providing opportunities for the design of hydrogen storage materials with unprecedented properties. In this review, we combed through the definition and criteria of high entropy alloys, and summarized the current research status of body-centred cubic-structured high entropy alloys for hydrogen storage from multiple perspectives of composition designs, synthesis processes, and hydrogen storage properties. Moreover, the possible application scenarios and future research directions are analysed. Copyright © 2023 Kong, Cheng, Wan and Xue.","Recently, high entropy alloys (HEAs) with body-centred cubic (BCC) single phase structures have attracted wide attention in many fields including hydrogen storage, due to their unique structural characteristics and excellent performance. Its novel design concept provides more possibilities for the investigation of advanced hydrogen storage materials, in which several remarkable research works have been published, providing opportunities for the design of hydrogen storage materials with unprecedented properties.",_
!042,"Sodium amide (NaNH2) in its α form is a common compound that has recently seen renewed interest, mainly for its potential use as a solid-state hydrogen storage material. In this work, we present a synergic theoretical and experimental characterization of the compound, including novel measured and simulated vibrational spectra (IR and Raman) and X-ray diffraction patterns. We put forward the hypothesis of a low-temperature symmetry breaking of the structure to space group C2/c, while space group Fddd is commonly reported in the literature and experimentally found down to 80 K. Additionally, we report a theoretical estimate of the heat of formation of sodium amide from ammonia to be equal to −12.2 kcal/mol at ambient conditions. © 2023 The Authors. Published by American Chemical Society","Sodium amide (NaNH2) in its α form is a common compound that has recently seen renewed interest, mainly for its potential use as a solid-state hydrogen storage material. We put forward the hypothesis of a low-temperature symmetry breaking of the structure to space group C2/c, while space group Fddd is commonly reported in the literature and experimentally found down to 80 K. Additionally, we report a theoretical estimate of the heat of formation of sodium amide from ammonia to be equal to −12.2 kcal/mol at ambient conditions.",_
!043,"Hydrogen energy has attracted a lot of interest as a renewable and sustainable energy source, but there are a few technical impediments associated with its storage. Solid-state hydrogen storage is a catching-on and intensively researched alternative to other methods for storing hydrogen. Perovskite hydrides exhibit the ability to store solid-state hydrogen safely and effectively. This work employs the first-principles calculations to investigate the physical properties of LiCaF3˗αHα (α = 0,1,2,3) perovskite compounds, aiming to elucidate insights into their potential in hydrogen storage applications. To assess the phase stability, we computed the formation enthalpies, which indicate that all compounds are stable and can be synthesized experimentally. Notably, the optimized lattice parameter decreased from 4.42 to 4.32 Å when an impurity was added to pristine material. Additionally, the evaluation of the elastic stiffness constants manifests that all LiCaF3-αHα compounds are mechanically stable and brittle in nature. Investigations of electronic properties demonstrate the narrowing in the bandgap of the host compound with the inclusion of H. To gain insight into how the absorption edge shifts towards the valence band and causes the band gap to diminish, the Burstein-Moss shift and band gap renormalization were investigated. Interestingly, the gravimetric and volumetric hydrogen storage capacities have been improved up to 6.04 wt% and 61.77 gH2l−1, respectively, which are fulfilling the target set by DOE for 2025. In short, this work suggests the applicability of LiCaH3 hydrides for effective hydrogen storage. © 2024 Elsevier Ltd","Perovskite hydrides exhibit the ability to store solid-state hydrogen safely and effectively. In short, this work suggests the applicability of LiCaH3 hydrides for effective hydrogen storage.",_
!044,"The high hydrogen storage capacity (10.5 wt.%) and release of hydrogen at a moderate temperature make LiAlH4 an appealing material for hydrogen storage. However, LiAlH4 suffers from slow kinetics and irreversibility. Hence, LaCoO3 was selected as an additive to defeat the slow kinetics problems of LiAlH4. For the irreversibility part, it still required high pressure to absorb hydrogen. Thus, this study focused on the reduction of the onset desorption temperature and the quickening of the desorption kinetics of LiAlH4. Here, we report the different weight percentages of LaCoO3 mixed with LiAlH4 using the ball-milling method. Interestingly, the addition of 10 wt.% of LaCoO3 resulted in a decrease in the desorption temperature to 70 °C for the first stage and 156 °C for the second stage. In addition, at 90 °C, LiAlH4 + 10 wt.% LaCoO3 can desorb 3.37 wt.% of H2 in 80 min, which is 10 times faster than the unsubstituted samples. The activation energies values for this composite are greatly reduced to 71 kJ/mol for the first stages and 95 kJ/mol for the second stages compared to milled LiAlH4 (107 kJ/mol and 120 kJ/mol for the first two stages, respectively). The enhancement of hydrogen desorption kinetics of LiAlH4 is attributed to the in situ formation of AlCo and La or La-containing species in the presence of LaCoO3, which resulted in a reduction of the onset desorption temperature and activation energies of LiAlH4. © 2023 by the authors.","Hence, LaCoO3 was selected as an additive to defeat the slow kinetics problems of LiAlH4. For the irreversibility part, it still required high pressure to absorb hydrogen.",_
!045,"Lithium aluminum hydride (LiAlH4) with a high hydrogen capacity of 10.5 wt% has become one of the most promising solid-state hydrogen storage materials for onboard hydrogen fuel cell systems. However, neither dehydrogenation kinetics nor cycling behaviors of LiAlH4 can fulfill the requirements of practical application. Here, we prepared the Ni/C nanoparticles anchored on large-size Ti3C2Tx nanosheets, firstly introduced into LiAlH4 to investigate its catalytic effect. Dehydrogenation experiments demonstrate that LiAlH4 doped with 7 wt% Ni/C@Ti3C2 starts to release hydrogen at 56.9 °C. Also, it can release about 4.3 wt% hydrogen within 50 min at 120 °C. The activation energies of LiAlH4 doped with 7 wt% Ni/C@Ti3C2 for the first and second steps are 34.5% and 53.2% lower than the as-received LiAlH4, respectively. Under 300 °C and 40 bar hydrogen, it can absorb 0.58 wt% hydrogen. It is found that in situ formed intermetallic Al2Ti during ball milling can weaken the Al-H bonds in LiAlH4 through interfacial charge transfer and the dehybridization, benefitting for the breaking of the Al-H bond in LiAlH4. In addition, Al2Ti can promote the adsorption and splitting of H2, contributing to the rehydrogenation of LiAlH4. © 2022 Elsevier B.V.","Here, we prepared the Ni/C nanoparticles anchored on large-size Ti3C2Tx nanosheets, firstly introduced into LiAlH4 to investigate its catalytic effect. Dehydrogenation experiments demonstrate that LiAlH4 doped with 7 wt% Ni/C@Ti3C2 starts to release hydrogen at 56.9 °C.",_
!046,"Solid-state storage of hydrogen molecules in carbon-based light metal single-atom materials is promising to achieve both high hydrogen storage capacity and uptake rate, but there is a lack of fundamental understanding and design principles to guide the rational design of the materials. Here, a theoretical relationship is established between the hydrogen capacity/rate and the structures of the heteroatom-doped-graphene-supported light metal Li single atom materials for high-efficient solid-state hydrogen storage, which is verified by combining spectroscopic characterization, H2 adsorption/desorption measurements, and density functional theory (DFT) calculations. Based on the DFT calculations, a novel descriptor Φ is developed to correlate the inherent properties of dopants with the hydrogen storage properties, and further to screen out the best dual-doped-graphene-supported light metal Li single-atom hydrogen storage materials. The dual-doped materials have a much higher hydrogen storage capability than the sole-doped ones and exceed the best carbon-based hydrogen storage materials so far. © 2024 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH.","Solid-state storage of hydrogen molecules in carbon-based light metal single-atom materials is promising to achieve both high hydrogen storage capacity and uptake rate, but there is a lack of fundamental understanding and design principles to guide the rational design of the materials. Here, a theoretical relationship is established between the hydrogen capacity/rate and the structures of the heteroatom-doped-graphene-supported light metal Li single atom materials for high-efficient solid-state hydrogen storage, which is verified by combining spectroscopic characterization, H2 adsorption/desorption measurements, and density functional theory (DFT) calculations.",_
!047,"We present a machine learning (ML) framework HEART (HydrogEn storAge propeRty predicTor) for identifying suitable families of metal alloys for hydrogen storage under ambient conditions. Our framework includes two ML models that predict the hydrogen storage capacity (HYST) and the enthalpy of hydride formation (THOR) of multi-component metal alloys. We demonstrate that a chemically diverse set of features effectively describes the hydrogen storage properties of the alloys. In HYST, we use absorption temperature as a feature which improved H2wt% prediction significantly. For out-of-the-bag samples, HYST predicted H2wt% with R2 score of 0.81 and mean absolute error (MAE) of 0.45 wt% whereas R2 score is 0.89 and MAE is 4.53 kJ/molH2 for THOR. These models are further employed to predict H2wt% and ΔH for ∼ 6.4 million multi-component metal alloys. We have identified 6480 compositions with superior storage properties (H2wt% > 2.5 at room temperature and ΔH < 60 kJ/molH2). We have also discussed in detail the interesting trends picked up by these models like temperature dependent variation in the rate of hydrogenation and alloying effect on H2wt% and ΔH in different families of alloys. Importantly certain elements like Al, Si, Sc, Cr, and Mn when mixed in small fractions with hydriding elements like Mg, Ti, V etc. systematically reduce ΔH without significantly compromising the storage capacity. Further upon increasing the number of elements in the alloy i.e from binary to ternary to quaternary, the number of compositions with lower enthalpies also increases. From the 6.4 million compositions, we have reported new alloy families having potential for hydrogen storage at room temperature. Finally, we demonstrate that HEART has the potential to scan vast chemical spaces by narrowing down potential materials for hydrogen storage. © 2023 Hydrogen Energy Publications LLC","These models are further employed to predict H2wt% and ΔH for ∼ 6.4 million multi-component metal alloys. From the 6.4 million compositions, we have reported new alloy families having potential for hydrogen storage at room temperature.",_
!048,"Magnesium hydride (MgH2) is the most prominent carrier for storing hydrogen in solid-state mode. However, their slow kinetics and high thermodynamics become an obstacle in hydrogen storage. The present study elaborates on the catalytic effect of graphene (Gr) and vanadium disulfide (VS2) on MgH2 to enhance its hydrogen sorption kinetic. The temperature-programmed desorption study shows that the onset desorption temperature of MgH2 catalyzed by VS2 and MgH2 catalyzed by Gr is 289 °C and 300 °C, respectively. These desorption temperatures are 87 °C and 76 °C lower than the desorption temperature of pristine MgH2. The rapid rehydrogenation kinetics for the MgH2 catalyzed by VS2 have been found at a temperature of 300 °C under 15 atm H2 pressure by absorbing ∼4.04 wt% of hydrogen within 1 min, whereas the MgH2 catalyzed by Gr takes ∼3 min for absorbing the same amount of hydrogen under the similar temperature and pressure conditions. The faster release of hydrogen was also observed in MgH2 catalyzed by VS2 than MgH2 catalyzed by Gr and pristine MgH2. MgH2 catalyzed by VS2 releases ∼2.54 wt% of hydrogen within 10 min, while MgH2 catalyzed by Gr takes ∼30 min to release the same amount of hydrogen. Furthermore, MgH2 catalyzed by VS2 also persists in the excellent cyclic stability and reversibility up to 25 cycles. © 2022 Hydrogen Energy Publications LLC","Magnesium hydride (MgH2) is the most prominent carrier for storing hydrogen in solid-state mode. Furthermore, MgH2 catalyzed by VS2 also persists in the excellent cyclic stability and reversibility up to 25 cycles.",_
!049,"The solid-state hydrogen storage in metal hydride (MH) is safer and energy efficient than the gaseous and liquid storage methods. The absorption of hydrogen in MH is highly exothermic. Hence, a good heat management system is required to increase the charging rate. The phase change material (PCM) can be integrated into the reactor to reuse the absorption heat for hydrogen desorption. The present numerical study models the concentric cylindrical reactor with magnesium (Mg) as MH surrounded by sodium nitrate (NaNO3) as PCM using COMSOL Multiphysics v6.1. The effect of buoyancy inside the PCM domain is investigated. An iterative approach is used to determine the required amount of PCM. Copper fins are added inside both MH and PCM. The effect of the number of fins, corresponding fin thickness and pitch on hydrogen absorption are determined to optimize the MH reactor. The outcomes reveal that the hydrogen absorption rate increases with fin numbers. The reactor with 10 and 30 fins takes 86.5 and 97.3 % less time than without fins for 90 % hydrogen absorption, respectively. The novel approach is proposed to estimate the fin efficiency (ηf) using temperature profiles of MH and fin during prevailing unsteady heat and mass transfer. The fin factor (Ff) is presented using the ηf and mass of MH. The performance evaluation criterion (PEC) is discussed based on hydrogen absorption relative to the system's weight. Further, the effect of operating parameters like hydrogen supply pressure and the initial temperature is studied on the reactor performance. © 2023 Elsevier Ltd","Hence, a good heat management system is required to increase the charging rate. An iterative approach is used to determine the required amount of PCM.",_
!050,"Complex aluminum hydrides with high hydrogen capacity are among the most promising solid-state hydrogen storage materials. The present study determines the thermal stability, hydrogen dissociation energy, and electronic structures of alkali metal aluminum hydrides, MAlH4 (M = Li, Na, K, and Cs), using first-principles density functional theory calculations in an attempt to gain insight into the dehydrogenation mechanism of these hydrides. The results show that the hydrogen dissociation energy (Ed-H2) of MAlH4 (M = Li, Na, K, and Cs) correlates with the Pauling electronegativity of cation M (χP); that is, the Ed-H2 (average value) decreases, i.e., 1.211 eV (LiAlH4) < 1.281 eV (NaAlH4) < 1.291 eV (KAlH4) < 1.361 eV (CsAlH4), with the increasing χP value, i.e., 0.98 (Li) > 0.93 (Na) > 0.82 (K) > 0.79 (Cs). The main reason for this finding is that alkali alanate MAlH4 at higher cation electronegativity is thermally less stable and held by weaker Al-H covalent and H-H ionic interactions. Our work contributes to the design of alkali metal aluminum hydrides with a favorable dehydrogenation, which is useful for on-board hydrogen storage. © 2023 by the authors.","The main reason for this finding is that alkali alanate MAlH4 at higher cation electronegativity is thermally less stable and held by weaker Al-H covalent and H-H ionic interactions. Our work contributes to the design of alkali metal aluminum hydrides with a favorable dehydrogenation, which is useful for on-board hydrogen storage.",_
!051,"One of the ideal energy carriers for the future is hydrogen. It has a high energy density and is a source of clean energy. A crucial step in the development of the hydrogen economy is the safety and affordable storage of a large amount of hydrogen. Thus, owing to its large storage capacity, good reversibility, and low cost, Magnesium hydride (MgH2) was taken into consideration. Unfortunately, MgH2 has a high desorption temperature and slow ab/desorption kinetics. Using the ball milling technique, adding cobalt lanthanum oxide (LaCoO3) to MgH2 improves its hydrogen storage performance. The results show that adding 10 wt.% LaCoO3 relatively lowers the starting hydrogen release, compared with pure MgH2 and milled MgH2. On the other hand, faster ab/desorption after the introduction of 10 wt.% LaCoO3 could be observed when compared with milled MgH2 under the same circumstances. Besides this, the apparent activation energy for MgH2–10 wt.% LaCoO3 was greatly reduced when compared with that of milled MgH2. From the X-ray diffraction analysis, it could be shown that in-situ forms of MgO, CoO, and La2O3, produced from the reactions between MgH2 and LaCoO3, play a vital role in enhancing the properties of hydrogen storage of MgH2. © 2023 by the authors.","Thus, owing to its large storage capacity, good reversibility, and low cost, Magnesium hydride (MgH2) was taken into consideration. Besides this, the apparent activation energy for MgH2–10 wt.% LaCoO3 was greatly reduced when compared with that of milled MgH2.",_
!052,"Magnesium hydride (MgH2) attracts wide interests as a promising hydrogen energy carrier, but its commercial application is hampered by the high operating temperatures and slow dehydrogenation kinetics. Herein, CrMnFeCoNi and CrFeCoNi high-entropy alloys (HEAs) were adopted to boost the hydrogen storage performance of MgH2. It was demonstrated that the morphology of catalysts and addition of Mn had a great impact on the performance of HEAs catalysts. In particular, the Mn containing HEAs nanosheets presented the best performance. The MgH2-CrMnFeCoNi composite could release 6.5 wt% H2 in 10 min at 300 °C and started to absorb H2 at 40 °C. Moreover, kinetic analysis revealed that the rate control model in dehydrogenation process of HEA-4 modified MgH2 changed from permeation model of MgH2 to diffusion. In addition, 97% hydrogen storage volume could be maintained after 20 cycles at 300 °C, showing a good cycling performance. Microstructure analysis showed that the CrMnFeCoNi nanosheets were uniform dispersed over the surface of MgH2, bringing numerous heterogeneous activation sites to speed up the dispersal of hydrogen. Besides, the cocktail effect of HEAs exerted synergic action between Cr, Mn, Fe, Co and Ni elements to improve the overall catalytic efficiency. Therefore, the de/rehydrogeantion performance of the MgH2-CrMnFeCoNi composite was surprisingly accelerated. © 2023 Elsevier B.V.","Magnesium hydride (MgH2) attracts wide interests as a promising hydrogen energy carrier, but its commercial application is hampered by the high operating temperatures and slow dehydrogenation kinetics. In addition, 97% hydrogen storage volume could be maintained after 20 cycles at 300 °C, showing a good cycling performance.",_
!053,"Currently, magnesium hydride (MgH2) as a solid-state hydrogen storage material has become the subject of major research owing to its good reversibility, large hydrogen storage capacity (7.6 wt%) and affordability. However, MgH2 has a high decomposition temperature (>400 °C) and slow desorption and absorption kinetics. In this work, BaMnO3 was synthesized using the solid-state method and was used as an additive to overcome the drawbacks of MgH2. Interestingly, after adding 10 wt% of BaMnO3, the initial desorption temperature of MgH2 decreased to 282 °C, which was 138 °C lower than that of pure MgH2 and 61 °C lower than that of milled MgH2. For absorption kinetics, at 250 °C in 2 min, 10 wt% of BaMnO3-doped MgH2 absorbed 5.22 wt% of H2 compared to milled MgH2 (3.48 wt%). Conversely, the desorption kinetics also demonstrated that 10 wt% of BaMnO3-doped MgH2 samples desorbed 5.36 wt% of H2 at 300 °C within 1 h whereas milled MgH2 only released less than 0.32 wt% of H2. The activation energy was lowered by 45 kJ/mol compared to that of MgH2 after the addition of 10 wt% of BaMnO3. Further analyzed by using XRD revealed that the formation of Mg0·9Mn0·1O, Mn3O4 and Ba or Ba-containing enhanced the performance of MgH2. © 2023 Hydrogen Energy Publications LLC","Currently, magnesium hydride (MgH2) as a solid-state hydrogen storage material has become the subject of major research owing to its good reversibility, large hydrogen storage capacity (7.6 wt%) and affordability. In this work, BaMnO3 was synthesized using the solid-state method and was used as an additive to overcome the drawbacks of MgH2.",_
!054,"The complex hydride NaAlH4 remains the archetype hydrogen storage system. In this paper, we have explored the catalytic action of Al65Cu20Fe15 quasicrystal (QC) on the de/re-hydrogenation study of NaAlH4. The leached ball-milled Al65Cu20Fe15 (LBMACF) catalyzed NaAlH4 sample has shown a lower hydrogen desorption temperature (140 °C) than other catalyzed and uncatalyzed NaAlH4 samples. NaAlH4-LBMACF rapidly absorbed ∼3.20 wt% of hydrogen within 1 min and absorbed maximum capacity (∼4.68 wt%) in 15 min, while NaAlH4-LACF, NaAlH4-BMACF, NaAlH4-ACF, and pristine NaAlH4 absorbed only 0.50 wt%, 1.38 wt%, 1.10 wt%, and 0.70 wt% in 1 min at 130 °C under 100 atm hydrogen pressure. NaAlH4-LBMACF has desorbed ∼4.22 wt% of hydrogen within 15 min, while the same amount of hydrogen desorbed by NaAlH4-LACF takes 45 min at 130 °C under 1 atm hydrogen pressure. NaAlH4-LBMACF shows reversibility up to 25 cycles with minimum degradation of hydrogen storage capacity of ∼0.06 wt% during de/re-hydrogenation. The catalytic mechanism and catalytic effect of Al–Cu–Fe on the NaAlH4 have been discussed using structural, microstructural analysis, in-situ nuclear magnetic resonance (NMR) spectroscopy, in-situ Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). © 2022 Hydrogen Energy Publications LLC","The leached ball-milled Al65Cu20Fe15 (LBMACF) catalyzed NaAlH4 sample has shown a lower hydrogen desorption temperature (140 °C) than other catalyzed and uncatalyzed NaAlH4 samples. The catalytic mechanism and catalytic effect of Al–Cu–Fe on the NaAlH4 have been discussed using structural, microstructural analysis, in-situ nuclear magnetic resonance (NMR) spectroscopy, in-situ Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS).",_
!055,"This study presents an experimental investigation conducted on an annular porous metal hydride reactor equipped with radial fins. The reactor was filled with 9 kg of La0.7Ce0.1Ca0.3Ni5, and water was considered as heat transfer fluid. The absorption characteristics were studied under different supply pressures (5–20 bar) and desorption characteristics under different inlet temperatures of heat transfer fluid (30–50 °C). An energy efficiency based on the higher heating value of hydrogen was evaluated for the developed solid-state hydrogen storage device. Further, the effect of pre-sensible heating on desorption performance and energy efficiency was analyzed. Finally, the experimental results were compared with the extensively studied LaNi5 alloy. The results showed that the alloy exhibited a constant desorption rate despite slower desorption kinetics. The energy efficiency of the developed system was found to be 76.76%. The comparison results showed that La0.7Ce0.1Ca0.3Ni5 exhibited higher storage capacity than LaNi5 after 20 cycles and approximately similar absorption and desorption rates. The desorption process without pre-sensible heating was more efficient and reduced overall desorption time by 46.5% than the desorption with pre-sensible heating. However, the desorption process without pre-sensible heating has not significantly affected the energy efficiency. © 2022 Elsevier Ltd","The absorption characteristics were studied under different supply pressures (5–20 bar) and desorption characteristics under different inlet temperatures of heat transfer fluid (30–50 °C). Further, the effect of pre-sensible heating on desorption performance and energy efficiency was analyzed.",_
!056,"Hydrogen energy is expected to be an “ideal fuel” in the era of decarbonization. The discovery, development, and modification of high-performance hydrogen storage materials are the keys to the future development of solid-state hydrogen storage and hydrogen energy utilization. Magnesium hydride (MgH2), with its high hydrogen storage capacity, abundant natural reserves, and environmental friendliness, has been extensively researched. Herein, we briefly summarize the typical structure and hydrogenation/dehydrogenation reaction mechanism of MgH2 and provide a comprehensive overview of strategies to effectively tune the thermodynamics and kinetics of Mg-based materials, such as alloying, nanosizing, the introduction of additives, and composite modification. With substantial efforts, great achievements have been achieved, such as lower absorption/desorption temperatures and better cycling stability. Nonetheless, some pivotal issues remain to be addressed, such as unfavorable hydrogenation/dehydrogenation factors, harsh conditions, slow kinetics, incomplete dehydrogenation, low hydrogen purity, expensive catalysts, and a lack of valid exploration of mechanisms in the hydrogenation/dehydrogenation process. Lastly, some future development prospects of MgH2 in energy-efficient conversion and storage have been presented, including advanced manufacturing ways, stabilization of nanostructures, the introduction of additives combined with structural modification, and utilization of advanced characterization techniques. © 2022","Magnesium hydride (MgH2), with its high hydrogen storage capacity, abundant natural reserves, and environmental friendliness, has been extensively researched. With substantial efforts, great achievements have been achieved, such as lower absorption/desorption temperatures and better cycling stability.",_
!057,"Solid-state hydrogen storage in various metal hydrides is among the most promising and clean way of storing energy, however, some problems, such as sluggish kinetics and high dehydrogenation temperature should be dealt with. In the present paper the advances of severe plastic deformation on the hydrogenation performance of metal hydrides will be reviewed. Techniques, like high-pressure torsion, equal-channel angular pressing, cold rolling, fast forging and surface modification have been widely applied to induce lattice defects, nanocrystallization and the formation of abundant grain boundaries in bulk samples and they have the potential to up-scale material production. These plastically deformed materials exhibit not only better H-sorption properties than their undeformed counterparts, but they possess better cycling performance, especially when catalysts are mixed with the host alloy promoting potential future applications.  ©2023 The Japan Institute of Metals and Materials.","Solid-state hydrogen storage in various metal hydrides is among the most promising and clean way of storing energy, however, some problems, such as sluggish kinetics and high dehydrogenation temperature should be dealt with. These plastically deformed materials exhibit not only better H-sorption properties than their undeformed counterparts, but they possess better cycling performance, especially when catalysts are mixed with the host alloy promoting potential future applications.",_
!058,"Sustainable development of hydrogen energy is a prime concern to address the rising energy demand and the global energy problem since the hydrogen economy is reliable for clean and carbon-free energy carriers. Despite well-established commercial sector technologies, boil-off losses, explosive nature, and leakage risk still exist with compressed and liquefied storage. One of the significant remedies, solid-state hydrogen storage, improves bulk density and gravimetric capacity and addresses safety concerns. The rising popularity of light and heavy fuel cell vehicles is projected to promote the advancement of onboard solid-state hydrogen technology. The present review focuses on the importance of existing porous materials, polymers, metal, and complex metal hydrides for solid-state hydrogen storage and the dominance of Si nanostructures (SiNSs). The fabrication techniques of porous silicon, porous silicon nanowires, and Si quantum dots are accentuated. The review provides insights into the hydrogen-assisted properties, regularities, the importance of hydrogen energy on automobiles for alleviating climate change phenomena, and the application of SiNSs for hydrogen storage with other transition and alkali earth materials to overcome the issues. It highlights the importance of catalysts in resolving the existing reversibility and desorption issues associated with hydrogen energy storage. Different popular desorption techniques considering the pore dimensions are discussed. The evaluation may enable energy providers and Si-based fuel cells to be better customized, promoting the development of the hydrogen energy economy. © 2022 Hydrogen Energy Publications LLC",The rising popularity of light and heavy fuel cell vehicles is projected to promote the advancement of onboard solid-state hydrogen technology. Different popular desorption techniques considering the pore dimensions are discussed.,_
!059,"The lattice distortion effect and cocktail effect of high-entropy oxides (HEOs) will dominate the catalytic effect of the materials, in order to study the influence of the constituent elements of HEOs on the lattice distortion effect and cocktail effect, through elemental manipulation of Cr, Cu, and La, high entropy oxides (HEOs) catalyst CrMnFeCoNiO (Cr1:1), CuMnFeCoNiO (Cu1:1), and LaMnFeCoNiO (La1:1) were effectively synthesized by the facile co-precipitation approach. With a size of about 10 nm, Cr1:1 presented significant modification impacts on enhancing the hydrogen storage capability of MgH2. Specifically, MgH2 was able to release hydrogen at 200 °C with the addition of Cr1:1, MgH2+10wt% Cr1:1 showed prompt rate of dehydrogenation which could release 5.56 wt% H2 in 20 min at 250 °C, and the activation energy of MgH2 was lowered to 69.77± 3.75 kJ⋅mol−1 by adding Cr1:1. According to the Chou model fitting, the exceptional kinetic performance of the composite was attributable to a rate-controlling step changed from low-speed surface penetration to high-speed diffusion. Furthermore, MgH2+10wt% Cr1:1 was capable of absorbing hydrogen at ambient temperature and the composite could uptake 6 wt% H2 within 8 min at the temperature of 150 °C. Due to the high entropy effects of HEOs, Cr1:1 possessed superior stability, which guarantees the robust cycling qualities of MgH2+10wt% Cr1:1. Meanwhile, microstructure analysis revealed that the active sites with numerous heterogeneous structures were uniformly dispersed on surfaces, exhibiting superior catalytic effects on improving the hydrogen storage performance of MgH2. © 2024","Furthermore, MgH2+10wt% Cr1:1 was capable of absorbing hydrogen at ambient temperature and the composite could uptake 6 wt% H2 within 8 min at the temperature of 150 °C. Meanwhile, microstructure analysis revealed that the active sites with numerous heterogeneous structures were uniformly dispersed on surfaces, exhibiting superior catalytic effects on improving the hydrogen storage performance of MgH2.",_
!060,"The quadrupole coupling constant CQ and the asymmetry parameter η have been determined for two complex aluminium hydrides from 27Al NMR spectra recorded for stationary samples by using the Solomon echo sequence. The thus obtained data for KAlH4 (CQ=(1.30±0.02) MHz, η=(0.64±0.02)) and NaAlH4 (CQ=(3.11±0.02) MHz, η<0.01) agree very well with data previously determined from MAS NMR spectra. The accuracy with which these parameters can be determined from static spectra turned out to be at least as good as via the MAS approach. The experimentally determined parameters (δiso, CQ and η) are compared with those obtained from DFT-GIPAW (density functional theory – gauge-including projected augmented wave) calculations. Except for the quadrupole coupling constant for KAlH4, which is overestimated in the GIPAW calculations by about 30 %, the agreement is excellent. Advantages of the application of the Solomon echo sequence for the measurement of less stable materials or for in situ studies are discussed. © 2023 The Authors. Published by Wiley-VCH GmbH.","The accuracy with which these parameters can be determined from static spectra turned out to be at least as good as via the MAS approach. The experimentally determined parameters (δiso, CQ and η) are compared with those obtained from DFT-GIPAW (density functional theory – gauge-including projected augmented wave) calculations.",_
!061,"Research on renewable energy and energy storage systems has been quite active as a result of the upcoming global challenge in both the energy and environmental domains. As a kind of clean energy with water as the only post-combustion product, hydrogen energy has been proposed as possible next-generation energy after decades of advancements. Despite advanced technologies have been developed for mass production of hydrogen from water splitting, hydrogen storage has always been an issue. Magnesium-based (Mg-based) solid-state hydrogen storage materials are promising due to their high energy storage densities, and research related to this field has skyrocketed in recent years. This paper discusses advanced research regarding the Mg-based solid-state hydrogen storage material and the new energy automobile market demand. The advantages and disadvantages and hydrogen storage performance of different Mg-based materials were compared, and the methods to improve the hydrogen storage density and hydrogen storage performance of the Mg-based hydrogen storage materials were summarized. It was found that Mg-based alloys are the most promising candidate for further industrial scale production, and the more advanced materials such as the Mg(BH)4 and the MgH2/graphene composites are the materials that need more research. Finally, applying Mg-based hydrogen fuel cells in new energy vehicles is promising. This paper hopes to provide the researchers with a state-of-the-art understanding of the advanced Mg-based hydrogen storage materials and hopefully help facilitate the hydrogen-related economy in the coming decades. © 2023 SPIE.","Magnesium-based (Mg-based) solid-state hydrogen storage materials are promising due to their high energy storage densities, and research related to this field has skyrocketed in recent years. Finally, applying Mg-based hydrogen fuel cells in new energy vehicles is promising.",_
!062,"High thermal stability and sluggish absorption/desorption kinetics are still important limitations for using magnesium hydride (MgH2) as a solid-state hydrogen storage medium. One of the most effective solutions in improving hydrogen storage properties of MgH2 is to introduce a suitable catalyst. Herein, a novel nanoparticulate ZrNi with 10-60 nm in size was successfully prepared by co-precipitation followed by a molten-salt reduction process. The 7 wt % nano-ZrNi-catalyzed MgH2 composite desorbs 6.1 wt % hydrogen starting from ∼178 °C after activation, lowered by 99 °C relative to the pristine MgH2 (∼277 °C). The dehydrided sample rapidly absorbs ∼5.5 wt % H2 when operating at 150 °C for 8 min. The remarkably improved hydrogen storage properties are reasonably ascribed to the in situ formation of ZrH2, ZrNi2, and Mg2NiH4 caused by the disproportionation reaction of nano-ZrNi during the first de-/hydrogenation cycle. These catalytic active species are uniformly dispersed in the MgH2 matrix, thus creating a multielement, multiphase, and multivalent environment, which not only largely favors the breaking and rebonding of H-H bonds and the transfer of electrons between H- and Mg2+ but also provides multiple hydrogen diffusion channels. These findings are of particularly scientific importance for the design and preparation of highly active catalysts for hydrogen storage in light-metal hydrides. © 2023 American Chemical Society.",High thermal stability and sluggish absorption/desorption kinetics are still important limitations for using magnesium hydride (MgH2) as a solid-state hydrogen storage medium. The dehydrided sample rapidly absorbs ∼5.5 wt % H2 when operating at 150 °C for 8 min.,_
!063,"Although MgH2 is widely regarded as one of the most promising solid-state hydrogen storage materials, the high operating temperature and sluggish kinetics of hydrogenation and dehydrogenation are major challenges for its practical application. Herein, V6O13 nanobelts with a thickness of 11 nm are fabricated to promote the reversible hydrogen storage performance of MgH2. The favorable interaction between V6O13 nanobelts and MgH2 leads to in situ homogeneous formation of metallic V during the initial dehydrogenation of MgH2. Induced by the catalysis of metallic V, which results in weaker structural stability and higher surface states of MgH2 attributed to the strong bonding interactions between V and H, the energy required for H2 desorption from MgH2 is decreased to 49.5 kJ mol−1, 10.9 kJ mol−1 lower than that of pristine MgH2. Moreover, during the reversible hydrogenation process, the catalysis of metallic V lowers the energy for H2 adsorption and dissociation on Mg down to −5.904 and 0.023 eV, respectively, while those values reach −0.086 and 1.103 eV for pristine Mg. As a result, with the introduction of V6O13 nanobelts with an ultralow content of 3 wt%, a systematic hydrogen storage capacity of 6.8 wt% could be retained at 250 °C after 10 cycles. © 2023 The Royal Society of Chemistry.","Although MgH2 is widely regarded as one of the most promising solid-state hydrogen storage materials, the high operating temperature and sluggish kinetics of hydrogenation and dehydrogenation are major challenges for its practical application. Induced by the catalysis of metallic V, which results in weaker structural stability and higher surface states of MgH2 attributed to the strong bonding interactions between V and H, the energy required for H2 desorption from MgH2 is decreased to 49.5 kJ mol−1, 10.9 kJ mol−1 lower than that of pristine MgH2.",_
!064,"AB5 type hydrogen storage alloys have been widely used in Ni-MH batteries due to their high electrochemical capacity, excellent rate performance, and low pollution. However, the high activation difficulty limited their development in the solid-state hydrogen storage field. Mechanical alloying to synthesize composites is an effective way to reduce activation energy. In this paper, the structure and hydrogen storage properties of the LaNi5+nAlH3 (n = 0, 1, 3 wt.%) composites were investigated. The results show that with the incremental of AlH3 alloying content, the lattice constant a, b, and c and the volume (V) of the LaNi5 unit cell tend to increase, the hydrogen absorption platform pressure of the composite material gradually decreased, and the hydrogen release platform pressure gradually increased. It resulted in a reduction in the hysteresis factor (Hf) of the composite from 0.66 to 0.35. This will reduce energy waste during energy conversion. In addition, the activation property of the alloy was improved after AlH3 alloying. This will facilitate the application of AB5 type hydrogen storage alloys.  © Published under licence by IOP Publishing Ltd.","AB5 type hydrogen storage alloys have been widely used in Ni-MH batteries due to their high electrochemical capacity, excellent rate performance, and low pollution. This will facilitate the application of AB5 type hydrogen storage alloys.",_
!065,"Lithium alanate (LiAlH4) is one of the most preferred materials for solid-state hydrogen storage materials owing to its relatively high hydrogen capacity (10.5 wt%). However, its high decomposition temperature and sluggish desorption kinetic restrict its potential application as a hydrogen storage medium for on-board hydrogen-powered applications. To overcome these problems, the impacts of Ni0.6Zn0.4O synthesized via a solid-state method on the desorption properties of LiAlH4 have been examined in this study. It was found that after the introduction of 10 wt% of Ni0.6Zn0.4O to LiAlH4, hydrogen started to release at 124 °C and 170 °C for the first two stages, respectively. Isothermal desorption kinetics also revealed that faster desorption kinetics can be observed at 90 °C for 120 min LiAlH4+10 wt% of Ni0.6Zn0.4O can desorb 3.1 wt% of H2, whereas undoped LiAlH4 can release approximately less than 0.5 wt% of H2 in the same time frame. According to the Kissinger method, the apparent activation energies for the first two steps of the LiAlH4+10 wt% of Ni0.6Zn0.4O composites have been found to be 73 kJ/mol and 85 kJ/mol, respectively, 32 kJ/mol and 40 kJ/mol less than milled LiAlH4. The in-situ formation of NiO and Zn or Zn-containing compounds during the heating process might contribute to the kinetic improvement of LiAlH4. © 2023 Hydrogen Energy Publications LLC","To overcome these problems, the impacts of Ni0.6Zn0.4O synthesized via a solid-state method on the desorption properties of LiAlH4 have been examined in this study. It was found that after the introduction of 10 wt% of Ni0.6Zn0.4O to LiAlH4, hydrogen started to release at 124 °C and 170 °C for the first two stages, respectively.",_
!066,"Magnesium hydride (MgH2) is the mostly used material for solid-state hydrogen storage. However, their slow kinetics and highly unfavorable thermodynamics make them unsuitable for the practical applications. The current study describes the unusual catalytic action of a new class of catalyst, a high-entropy alloy (HEA) of Al20Cr16Mn16Fe16Co16Ni16 and its leached version, on the de/re-hydrogenation properties of MgH2. The onset desorption temperature of MgH2 was reduced significantly from 360 °C (for ball-milled MgH2) to 338 °C when it was catalyzed with a leached HEA-based catalyst. On the other hand, a fast de/re-hydrogenation kinetics of MgH2 was observed during the addition of leached HEA-based catalyst. It absorbed ∼6.1 wt% of hydrogen in just 2 min at a temperature of 300 °C under 10 atm hydrogen pressure and desorbed ∼5.4 wt% within 40 min. At moderate temperatures and low pressure, the HEA-based catalyst reduced desorption temperatures and improved re-hydrogenation kinetics. Even after 25 cycles of de/re-hydrogenation, the storage capacity of MgH2 catalyzed with the leached version of HEA degrades negligibly. © 2023 Hydrogen Energy Publications LLC","Magnesium hydride (MgH2) is the mostly used material for solid-state hydrogen storage. However, their slow kinetics and highly unfavorable thermodynamics make them unsuitable for the practical applications.",_
!067,"Ammonia borane (AB) has been extensively studied as a solid-state hydrogen storage material. On the other hand, its reactivity with CO2 is still unclear, especially in the solid state. By carefully controlling the CO2 pressure and temperature, AB efficiently reduces a large amount of CO2 without solvent or catalyst. 40 mmol of CO2 reacts with one mole of AB at 0.5 MPa and 60 °C. The mechanism was investigated by NMR and DFT calculation. The reaction proceeds through the formation of diammoniate of diborane (DADB) as an intermediate, followed by the reduction and fixation of CO2 with BH4− to give triformatoborohydride ([HB(OCHO)3]−). Aldehyde is then transferred from B to N, yielding formamide as the main final product. The N-formylation of secondary amine can also be achieved without solvent. Finally, the pyrolysis of the product between AB and CO2 produces N-doped amorphous carbon, opening the door to new clean CO2 valorisation pathways. © 2024 The Royal Society of Chemistry.","By carefully controlling the CO2 pressure and temperature, AB efficiently reduces a large amount of CO2 without solvent or catalyst. Aldehyde is then transferred from B to N, yielding formamide as the main final product.",_
!068,"Over the last few decades, hydrogen fuel has been considered to be a major alternative source of renewable energy due to increasing environmental pollution and the depletion of nonrenewable energy. The need to efficiently produce and store hydrogen, therefore, has necessitated the development of several technologies and materials for hydrogen storage to achieve the envisaged hydrogen economy. Solid-state hydrogen storage in magnesium hydride (MgH2) has shown a huge potential owing to its impressively high gravimetric and volumetric hydrogen capacities of ca. 7.6 wt% and 111 g/L, respectively. However, the bottleneck to the wide applications of MgH2 as a commercial source of hydrogen fuel is the delivery temperature requirement of ca. 300-400°C due to thermodynamic stability (ca. 76 kJ/mol-H2), and the slow kinetics of hydrogen de/absorption. Nanostructuring and catalysis are marked as the most promising strategies for modifying the properties of MgH2. Doping MgH2 with nanoscale materials can lower the delivery temperature and bring it nearer to commercial applications. Recently, MXenes, a group of 2D nanomaterials composed of transition metal carbides/nitrides/carbonitrides layers, have demonstrated the dual roles of storing hydrogen and enhancing the hydrogen evolution reactions of lightweight metal hydrides especially MgH2. This review article, therefore, provides explicit insights into MXenes, their recent applications as potential materials for storing hydrogen, and as functional additives for enhancing the hydrogen reaction of MgH2 with an outlook. © 2022","Doping MgH2 with nanoscale materials can lower the delivery temperature and bring it nearer to commercial applications. This review article, therefore, provides explicit insights into MXenes, their recent applications as potential materials for storing hydrogen, and as functional additives for enhancing the hydrogen reaction of MgH2 with an outlook.",_
!069,"Solid-state hydrogen storage materials have been considered as one of the most promising hydrogen storage methods due to the advantages of high volumetric density, flexible transportation, good safety, etc. The development of hydrides with reversible hydrogen capability at low temperature (<80 ℃) is of great significance for expanding the application of solid-state hydrogen storage technology. The low thermodynamic stability of transition metal alanates may meet the low-temperature requirements of hydrogen storage systems, which has the potential values of fundamental research and applications. This paper not only systematically reviews the research progress of transition metal alanates, including the preparation methods, structural and property characterizations, underlying mechanisms, etc., but also discusses the main problems and development trend, which aims to provide reference for the further study of transition metal alanates. © 2023 Materials China. All rights reserved.","Solid-state hydrogen storage materials have been considered as one of the most promising hydrogen storage methods due to the advantages of high volumetric density, flexible transportation, good safety, etc. This paper not only systematically reviews the research progress of transition metal alanates, including the preparation methods, structural and property characterizations, underlying mechanisms, etc., but also discusses the main problems and development trend, which aims to provide reference for the further study of transition metal alanates.",_
!070,"Hydrogen energy is regarded as the clean energy with the most development potential. In order to realize the large-scale application of hydrogen energy, the problem of hydrogen storage must be solved. At present, there are three main ways of hydrogen storage, namely compressed hydrogen storage, liquid hydrogen storage, and solid-state hydrogen storage. Compressed hydrogen storage is the most commonly used hydrogen storage method. After the hydrogen is compressed, it is stored in the form of gas in a cylinder. It has the advantages of low cost and fast charging and discharging speed, but its volumetric hydrogen storage density is extremely low. Liquid hydrogen storage is a cryogenic hydrogen storage technology. After the hydrogen is compressed, it is cryogenically cooled to below −253°C to become liquid hydrogen for storage. Liquid hydrogen has the advantages of high storage efficiency and good volumetric hydrogen storage density, but the liquefaction of hydrogen requires a lot of energy, so its storage cost is high. Solid-state hydrogen storage technology is one of the most promising hydrogen storage technologies, which utilizes the physical adsorption or chemical reaction characteristics between hydrogen and materials to store hydrogen. It has the advantages of good safety and high volumetric hydrogen storage density. Therefore, solid-state hydrogen storage is considered to be one of the most promising hydrogen storage technologies. However, in order to develop solid-state hydrogen storage technology, we must find and develop high-performance hydrogen storage materials, which have become a top priority. The current chapter mainly presents an overview of the developments of three hydrogen storage technologies. In particular, the solid-state hydrogen storage technology and hydrogen storage alloys are emphatically introduced. © 2024 Elsevier Inc. All rights reserved.","It has the advantages of good safety and high volumetric hydrogen storage density. However, in order to develop solid-state hydrogen storage technology, we must find and develop high-performance hydrogen storage materials, which have become a top priority.",_
!071,"This work investigates the graphitic carbon nitride (g-C3N4) and g-C3N4/CoMn2O4 nanocomposites as potential materials for solid-state hydrogen storage applications. Initially, the CoMn2O4 was prepared by facile hydrothermal technique and g-C3N4 was synthesized via a one-step calcination process. The g-C3N4/CoMn2O4 composites were prepared through ultrasonic-assisted wet impregnation method and their physical and chemical properties were investigated systematically. Thermogravimetric analysis confirmed that the samples were thermally stable up to 500 °C. Hydrogenation studies were carried out at 150 °C for 30 min under 5 and 10 bar pressures. In the dehydrogenation process, the g-C3N4 desorbed 1.58 wt% and g-C3N4/CoMn2O4 650 nanocomposite desorbed 2.25 wt% of hydrogen from RT to 500 °C. The g-C3N4/CoMn2O4 650 shows lower desorption activation energy and binding energy (Ed = 15.81 kJ mol−1 & Eb = 0.252 eV) compared to g-C3N4 (Ed = 16.54 kJ mol−1 & Eb = 0.260 eV) respectively. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.",This work investigates the graphitic carbon nitride (g-C3N4) and g-C3N4/CoMn2O4 nanocomposites as potential materials for solid-state hydrogen storage applications. Hydrogenation studies were carried out at 150 °C for 30 min under 5 and 10 bar pressures.,_
!072,"This study emphasizes the catalytic function of TiF3 on hydrogen storage properties and the reaction mechanism of the MgH2-Na3AlH6-LiBH4 produced by employing the ball-milling technique, which has a molar ratio of 1:1:4. It discovered that the mixture of Na3AlH6 and LiBH4 reacted through a metathesis reaction and transformed into Li3AlH6 and NaBH4 composite upon the ball milling procedure. MgH2-Li3AlH6-NaBH4 destabilized system with TiF3 catalyst has displayed four decomposition tiers throughout the heating procedure. The initial tier of hydrogen release in the composite occurs at temperatures of 100 °C and 75 °C lower than in the catalyst-free composite. Continuous heating resulted in two through four dehydrogenation tiers, with an overall capacity of 10.1 wt% hydrogens released (at temperatures of 200 °C, 350 °C, and 400 °C, respectively). In contrast to the Mg-Na-Al-Li-B-H catalyst-free composite, incorporating the TiF3 catalyst demonstrates a faster hydrogen uptake and release rate. The apparent activation energy (Ea) for the dissociation of Li3AlH6, MgH2, and NaBH4 in the composite with TiF3 catalyst was remarkably abridged compared to the catalyst-free ternary system (Kissinger plot; 23, 20, and 13 kJ/mol, respectively for doped composite). TiF3's considerable catalytic performance is ascribed to the in-situ production of Al[sbnd]Ti and Al[sbnd]F phases during the dehydrogenation process of TiF3 and Li3AlH6. Once generated, the Al[sbnd]Ti and Al[sbnd]F phase serves as a genuine catalyst in the MgH2-Na3AlH6-4LiBH4-TiF3 ternary system. © 2023 Elsevier Ltd",MgH2-Li3AlH6-NaBH4 destabilized system with TiF3 catalyst has displayed four decomposition tiers throughout the heating procedure. TiF3's considerable catalytic performance is ascribed to the in-situ production of Al[sbnd]Ti and Al[sbnd]F phases during the dehydrogenation process of TiF3 and Li3AlH6.,_
!073,"Although Mg-based hydrides are extensively considered as a prospective material for solid-state hydrogen storage and clean energy carriers, their high operating temperature and slow kinetics are the main challenges for practical application. Here, a Mg–Ni based hydride, Mg2NiH4 nanoparticles (∼100 nm), with dual modification strategies of nanosizing and alloying is successfully prepared via a gas-solid preparation process. It is demonstrated that Mg2NiH4 nanoparticles form a unique chain-like structure by oriented stacking and exhibit impressive hydrogen storage performance: it starts to release H2 at ∼170 °C and completes below 230 °C with a saturated capacity of 3.32 wt% and desorbs 3.14 wt% H2 within 1800 s at 200 °C. The systematic characterizations of Mg2NiH4 nanoparticles at different states reveal the dehydrogenation behavior and demonstrate the excellent structural and hydrogen storage stabilities during the de/hydrogenated process. This research is believed to provide new insights for optimizing the kinetic performance of metal hydrides and novel perspectives for designing highly active and stable hydrogen storage alloys. © 2023 The Authors","Although Mg-based hydrides are extensively considered as a prospective material for solid-state hydrogen storage and clean energy carriers, their high operating temperature and slow kinetics are the main challenges for practical application. This research is believed to provide new insights for optimizing the kinetic performance of metal hydrides and novel perspectives for designing highly active and stable hydrogen storage alloys.",_
!074,"For solid-state hydrogen storage, Mg(BH4)2 has long been recognized as a promising material. However, its higher thermal stability is distant from conditions for practical application. Herein, it is effectively established that VF4 nanoparticles anchored on 2D Mxene Ti3C2 (VF4@Ti3C2) have efficiently catalytic effects towards the hydrogen storage process of Mg(BH4)2. The MBH-VF4@Ti3C2 sample started releasing hydrogen at 90 °C, which was 182 °C and 55 °C lower than those of additive-free Mg(BH4)2 and MBH-20Ti3C2 composites. Additionally, the MBH-20VF4@Ti3C2 composite desorbed more than 8 wt% H2 at 275 °C. The activation energies of dehydrogenation were reduced, and the improved reversibility of VF4@Ti3C2-doped Mg(BH4)2 was also discussed. According to microstructural study, the heterostructural VF4@Ti3C2 interacted with Mg(BH4)2 to produce VH2.01 and metallic Ti during re/dehydrogenation, which worked as active species to improve hydrogen storage performance in Mg(BH4)2. © 2023 Elsevier B.V.","For solid-state hydrogen storage, Mg(BH4)2 has long been recognized as a promising material. Herein, it is effectively established that VF4 nanoparticles anchored on 2D Mxene Ti3C2 (VF4@Ti3C2) have efficiently catalytic effects towards the hydrogen storage process of Mg(BH4)2.",_
!075,"As an ideal material for solid-state hydrogen storage, magnesium hydride (MgH2) has attracted enormous attention due to its cost-effectiveness, abundant resources, and outstanding reversibility. However, the high thermodynamics and poor kinetics of MgH2 still hinder its practical application. In this work, a simple stirring-hydrothermal method was used to successfully prepare bimetallic Mn3O4/ZrO2 nanoparticles, which were subsequently doped into MgH2 by mechanical ball milling to improve its hydrogen sorption performance. The MgH2 + 10 wt% Mn3O4/ZrO2 composite began discharging hydrogen at 219 °C, which was 111 °C lower compared to the as-synthesized MgH2. At 250 °C, the MgH2 + 10 wt% Mn3O4/ZrO2 composite released 6.4 wt% hydrogen within 10 min, whereas the as-synthesized MgH2 reluctantly released 1.4 wt% hydrogen even at 335 °C. Moreover, the dehydrogenated MgH2 + 10 wt% Mn3O4/ZrO2 sample started to charge hydrogen at room temperature. 6.0 wt% hydrogen was absorbed when heated to 250 °C under 3 MPa H2 pressure, and 4.1 wt% hydrogen was taken up within 30 min at 100 °C at the same hydrogen pressure. In addition, compared with the as-synthesized MgH2, the de/rehydrogenation activation energy values of the MgH2 + 10 wt% Mn3O4/ZrO2 composite were decreased to 64.52 ± 13.14 kJ mol−1 and 16.79 ± 4.57 kJ mol−1, respectively, which incredibly contributed to the enhanced hydrogen de/absorption properties of MgH2 © 2023 The Royal Society of Chemistry.","As an ideal material for solid-state hydrogen storage, magnesium hydride (MgH2) has attracted enormous attention due to its cost-effectiveness, abundant resources, and outstanding reversibility. However, the high thermodynamics and poor kinetics of MgH2 still hinder its practical application.",_
!076,"Vanadium-based alloys are considered to be one of the most promising hydrogen storage materials due to their high hydrogen storage capacity under ambient conditions. However, their complex activation at high temperature and poor stability pose serious challenges for large-scale applications. In this work, a series of TiCr3V16Cex (x = 0, 0.1, 0.2, 0.4, 1) hydrogen storage alloys were developed with different Ce contents using arc melting. The hydrogen storage and desorption performance, activation mechanism, and hydrogen absorption mechanism of the prepared alloys were investigated. Physical characterization confirms that the alloy is body-centered cubic (BCC) with Ce dopants, which exist in the form of oxides. The pressure-composition-temperature (PCT) test showed that the hydrogen storage plateau pressure of the Ce-doped alloy is increased compared to the Ce-free counterparts, while the hydrogen storage capacity decreased slightly with increasing Ce content. In addition, the influence of Ce doping on the alloy kinetics and thermodynamics is also discussed. The results showed that the TiCr3V16Cex (x = 0.2, 0.4, 1) alloys could absorb and release hydrogen at room temperature without activation. As an optimum, the TiCr3V16Ce0.2 alloy shows a hydrogen absorption rate of up to 3.69 wt%, and an effective hydrogen desorption capacity of 2.29 wt% at 25 °C. After hydrogen absorption and desorption cycles, the alloy almost maintains its original capacity. The Ce-doped BCC alloy developed in this work provides a new route to achieve high hydrogen storage performance under mild conditions. © 2022 Elsevier B.V.","In this work, a series of TiCr3V16Cex (x = 0, 0.1, 0.2, 0.4, 1) hydrogen storage alloys were developed with different Ce contents using arc melting. The Ce-doped BCC alloy developed in this work provides a new route to achieve high hydrogen storage performance under mild conditions.",_
!077,"Hydrogen-based economy has a great potential for addressing the world's environmental concerns by using hydrogen as its future energy carrier. Hydrogen can be stored in gaseous, liquid and solid-state form, but among all solid-state hydrogen storage materials (metal hydrides) have the highest energy density. However, hydrogen accessibility is a challenging step in metal hydride-based materials. To improve the hydrogen storage kinetics, effects of functionalized catalysts/dopants on metal atoms have been extensively studied. The nanostructuring of metal hydrides is a new focus and has enhanced hydrogen storage properties by allowing higher surface area and thus reversibility, hydrogen storage density, faster and tunable kinetics, lower absorption and desorption temperatures, and durability. The effect of incorporating nanoparticles of carbon-based materials (graphene, C60, carbon nanotubes (CNTs), carbon black, and carbon aerogel) showed improved hydrogen storage characteristics of metal hydrides. In this critical review, the effects of various carbon-based materials, catalysts, and dopants are summarized in terms of hydrogen-storage capacity and kinetics. This review also highlights the effects of carbon nanomaterials on metal hydrides along with advanced synthesis routes, and analysis techniques to explore the effects of encapsulated metal hydrides and carbon particles. In addition, effects of carbon composites in polymeric composites for improved hydrogen storage properties in solid-state forms, and new characterization techniques are also discussed. As is known, the nanomaterials have extremely higher surface area (100–1000 time more surface area in m2/g) when compared to the bulk scale materials; thus, hydrogen absorption and desorption can be tuned in nanoscale structures for various industrial applications. The nanoscale tailoring of metal hydrides with carbon materials is a promising strategy for the next generation of solid-state hydrogen storage systems for different industries. © 2023 Hydrogen Energy Publications LLC","Hydrogen-based economy has a great potential for addressing the world's environmental concerns by using hydrogen as its future energy carrier. To improve the hydrogen storage kinetics, effects of functionalized catalysts/dopants on metal atoms have been extensively studied.",_
!078,"Solid-state hydrogen storage is the best choice for balancing economy and safety among various hydrogen storage technologies, and hydrogen storage in the secondary phase might be a promising solid-state hydrogen storage scheme. In the current study, to unmask its physical mechanisms and details, a thermodynamically consistent phase-field framework is built for the first time to model hydrogen trapping, enrichment, and storage in the secondary phases of alloys. The hydrogen trapping processes, together with hydrogen charging, are numerically simulated using the implicit iterative algorithm of the self-defined finite elements. Some important results are attained: 1. Hydrogen can overcome the energy barrier under the assistance of the local elastic driving force and then spontaneously enter the trap site from the lattice site. The high binding energy makes it difficult for the trapped hydrogens to escape. 2. The secondary phase geometry stress concentration significantly induces the hydrogen to overcome the energy barrier. 3. The manipulation of the geometry, volume fraction, dimension, and type of the secondary phases is capable of dictating the tradeoff between the hydrogen storage capacity and the hydrogen charging rate. The new hydrogen storage scheme, together with the material design ideology, promises a viable path toward the optimization of critical hydrogen storage and transport for the hydrogen economy. © 2023 by the authors.","Solid-state hydrogen storage is the best choice for balancing economy and safety among various hydrogen storage technologies, and hydrogen storage in the secondary phase might be a promising solid-state hydrogen storage scheme. In the current study, to unmask its physical mechanisms and details, a thermodynamically consistent phase-field framework is built for the first time to model hydrogen trapping, enrichment, and storage in the secondary phases of alloys.",_
!079,"The ability of high-entropy alloys (HEAs) for hydrogen storage is a rather new topic in the hydrogen community. HEAs with the C14 Laves phase have shown a high potential to reversibly store hydrogen at room temperature, but most of these alloys require a high-temperature activation treatment. This study explores the role of interphase boundaries on the easy activation of HEAs at room temperature. Two chemically similar HEAs with single and dual phases, TiV1.5ZrCr0.5MnFeNi (C14 + 4 vol% BCC phases) and TiV1.5Zr1.5CrMnFeNi (single C14 phase), are designed and synthesized. While the dual-phase alloy readily absorbs hydrogen at room temperature without any activation treatment, the single-phase alloy requires a high-temperature activation. It is suggested that interphase boundaries not only provide pathways for easy hydrogen transport and activation of HEAs at room temperature but also act as active sites for heterogeneous nucleation of hydride. This study introduces interphase-boundary generation as an effective strategy to address the activation drawback of HEAs. © 2023 Hydrogen Energy Publications LLC",It is suggested that interphase boundaries not only provide pathways for easy hydrogen transport and activation of HEAs at room temperature but also act as active sites for heterogeneous nucleation of hydride. This study introduces interphase-boundary generation as an effective strategy to address the activation drawback of HEAs.,_
!080,"Solid-state hydrogen storage is crucial for the widespread applications of hydrogen energy. It is a grand challenge to find appropriate materials that provide high hydrogen density and ambient temperature stability. Herein, we investigated the potential of Ti-decorated Irida-Graphene, a promising effective hydrogen storage system, as a novel hydrogen storage material using first-principles calculation. Irida-Graphene is a two-dimensional isomer of carbon consisting of tri-, hexa-, and octagon rings of carbon. Ti atoms are tightly bounded to the hexagonal rings. Binding energy analysis reveals that a single Ti atom in the primitive unit-cell of Ti-decorated Irida-Graphene is capable to bind up with 5H2 molecules and the average adsorption energy was −0.41 eV/H2. It indicates the gravimetric density of 7.7 wt%. The stability is attributed to Kubas-type interactions and ensured by a 5.0 eV diffusion energy barrier that prevents the Ti–Ti clustering. Further, ab initio molecular dynamics simulations results illustrate that the system remains stable at 600 K, higher than the desorption temperature of 524 K, implying the stability of the system during hydrogen recharge and discharge. The exceptional hydrogen storage performance suggests that Ti-decorated Irida-Graphene is an outstanding candidate for hydrogen storage materials. © 2023 Hydrogen Energy Publications LLC",It is a grand challenge to find appropriate materials that provide high hydrogen density and ambient temperature stability. Binding energy analysis reveals that a single Ti atom in the primitive unit-cell of Ti-decorated Irida-Graphene is capable to bind up with 5H2 molecules and the average adsorption energy was −0.41 eV/H2.,_
!081,"The catalytic effect of FeCoNiCrMo high entropy alloy nanosheets on the hydrogen storage performance of magnesium hydride (MgH2) was investigated for the first time in this paper. Experimental results demonstrated that 9wt% FeCoNiCrMo doped MgH2 started to de-hydrogenate at 200°C and discharged up to 5.89wt% hydrogen within 60 min at 325°C. The fully dehydrogenated composite could absorb 3.23wt% hydrogen in 50 min at a temperature as low as 100°C. The calculated de/hydrogenation activation energy values decreased by 44.21%/55.22% compared with MgH2, respectively. Moreover, the composite’s hydrogen capacity dropped only 0.28wt% after 20 cycles, demonstrating remarkable cycling stability. The microstructure analysis verified that the five elements, Fe, Co, Ni, Cr, and Mo, remained stable in the form of high entropy alloy during the cycling process, and synergistically serving as a catalytic union to boost the de/hydrogenation reactions of MgH2. Besides, the FeCoNiCrMo nanosheets had close contact with MgH2, providing numerous non-homogeneous activation sites and diffusion channels for the rapid transfer of hydrogen, thus obtaining a superior catalytic effect. © 2023, University of Science and Technology Beijing.","Moreover, the composite’s hydrogen capacity dropped only 0.28wt% after 20 cycles, demonstrating remarkable cycling stability. Besides, the FeCoNiCrMo nanosheets had close contact with MgH2, providing numerous non-homogeneous activation sites and diffusion channels for the rapid transfer of hydrogen, thus obtaining a superior catalytic effect.",_
!082,"Hydrogen-based energy systems offer potential solutions for replacing fossil fuels in the future. However, the practical utilization of hydrogen energy depends partly on safe and efficient hydrogen storage techniques. The development of hydrogen storage materials has attracted extensive interest for decades. Solid-state hydrogen storage systems based on metal hydride materials provide great promises for many applications. Recently, interest has been revived in TiFe alloys as a prime candidate for stationary hydrogen storage material. The advantages of TiFe alloys over some of the other solid metal hydrides include that it can hydrogenate and dehydrogenate at near room temperature under near atmospheric pressures and that it is a low-cost material because there are abundant supplies of Fe and Ti on the earth's crust. However, the TiFe alloy must be activated at relatively high temperatures (400–450 °C) and high pressure of hydrogen (65 bar) before it can be hydrogenated, which is a hindrance to the industrial-scale application of TiFe alloys. The materials science community on hydrogen storage materials has conducted and reported considerable amounts of studies on TiFe-based alloys. In this work, we provided a comprehensive review of TiFe-based alloys. The fundamentals and synthesis approaches of TiFe-based alloys were summarized. The activation properties of TiFe-based alloys including the understanding of the activation mechanisms and the methods for improving the activation kinetics were reviewed. Moreover, the cycle stability and anti-poisoning ability were discussed. Finally, the potential applications and the perspective of TiFe-based alloys were introduced. © 2023 Elsevier Ltd","Solid-state hydrogen storage systems based on metal hydride materials provide great promises for many applications. Recently, interest has been revived in TiFe alloys as a prime candidate for stationary hydrogen storage material.",_
!083,"Solid-state hydrogen storage has emerged as an efficient and reliable technique to commercialize hydrogen energy on a large scale. Magnesium hydride (MgH2), amongst other materials, shows excellent hydrogen storage capability. However, it suffers from setbacks like sluggish kinetics and high thermodynamic stability. Several studies have shown that doping with suitable materials is an effective method to improve the sorption kinetics. Current work is concerned with doping of MgH2 with perovskite-type ternary metal oxide NaNbO3 at 5,10 & 15 wt% doping concentration via ball milling and study of its sorption properties. Thermal desorption mass spectra (TDMS) with thermogravimetry (TG) and Differential scanning calorimetry (DSC) validate the optimum doping concentration to be 10 wt% NaNbO3 in MgH2. According to the isothermal hydrogenation plots, 10 wt% catalyzed sample was capable of absorbing 5.29 wt% hydrogen in just 4.2 min at 150ºC which by far outperforms the 2 h milled MgH2 sample which under the same set of conditions absorbs only 0.67 wt% H2. The catalyst starts affecting the absorption rate right from the room temperature whereas the milled sample has minimal absorption throughout the experiment. At room temperature, the average rate of absorption grows by factor 7 which is staggeringly high. The Kissinger analysis reveals activation energy for hydrogen release as 73.12 kJ/mol for 10 wt% doped NaNbO3-MgH2 system while 137.13 kJ/mol for as milled MgH2. The pressure-temperature isotherm (PCI) at four different temperatures gives a quantitative measure of the thermodynamic stability of the system. To fully comprehend the catalytic process, XRD, SEM, and XPS analysis were conducted after each stage of experiment. XPS suggested possible reduction of Nb valance state from + 5 to + 2 due to surface reduction reaction which further accelerated the sorption kinetics due to the electron transfer process. © 2023 Elsevier B.V.","Thermal desorption mass spectra (TDMS) with thermogravimetry (TG) and Differential scanning calorimetry (DSC) validate the optimum doping concentration to be 10 wt% NaNbO3 in MgH2. To fully comprehend the catalytic process, XRD, SEM, and XPS analysis were conducted after each stage of experiment.",_
!084,"Solid-state hydrogen storage device using metal hydride have enormous advantages for fuel cell forklifts. In addition to high volume hydrogen storage density, the solid-state hydrogen storage device can also be used as a counterweight for the forklift. At the same time, the solid-state storage device has low hydrogen storage pressure and safety, and the fuel (H2) refueling is convenient and low-cost. In this paper, a two-dimensional heat and mass transfer numerical model has been developed to predicting the performance of the metal hydride tank filled with Ti0.9Zr0.1Cr0.35Mn1.4V0.2Fe0.05 alloy. The validity of this numerical model was tested by comparison with the experimental data of the metal hydride hydrogen storage tank with a hydrogen capacity of 1 kg, achieving a good agreement between all the data. And a solid-state hydrogen storage device with an effective hydrogen capacity of 1.5 kg is optimally designed for 3.5 T fuel cell forklift. The completion rate of hydrogen refueling in the solid-state hydrogen storage device will reach 97.6 % within 30 min, and continuously discharging over 1.5 kg H2 under flow rates of 150 SL/min and 250 SL/min. The optimized solid-state hydrogen storage device was integrated in a power module for 3.5 T fuel cell forklift which allows uninterrupted operation for at least 6 h 8 min under rated operation. © 2023",Solid-state hydrogen storage device using metal hydride have enormous advantages for fuel cell forklifts. The optimized solid-state hydrogen storage device was integrated in a power module for 3.5 T fuel cell forklift which allows uninterrupted operation for at least 6 h 8 min under rated operation.,_
!085,"As a high-density solid-state hydrogen storage material, magnesium hydride (MgH2) is promising for hydrogen transportation and storage. Yet, its stable thermodynamics and sluggish kinetics are unfavorable for that required for commercial application. Herein, nickel/vanadium trioxide (Ni/V2O3) nanoparticles with heterostructures were successfully prepared via hydrogenating the NiV-based two-dimensional layered double hydroxide (NiV-LDH). MgH2 + 7 wt% Ni/V2O3 presented more superior hydrogen absorption and desorption performances than pure MgH2 and MgH2 + 7 wt% NiV-LDH. The initial discharging temperature of MgH2 was significantly reduced to 190 °C after adding 7 wt% Ni/V2O3, which was 22 and 128 °C lower than that of 7 wt% NiV-LDH modified MgH2 and additive-free MgH2, respectively. The completely dehydrogenated MgH2 + 7 wt% Ni/V2O3 charged 5.25 wt% H2 in 20 min at 125 °C, while the hydrogen absorption capacity of pure MgH2 only amounted to 4.82 wt% H2 at a higher temperature of 200 °C for a longer time of 60 min. Moreover, compared with MgH2 + 7 wt% NiV-LDH, MgH2 + 7 wt% Ni/V2O3 shows better cycling performance. The microstructure analysis indicated the heterostructural Ni/V2O3 nanoparticles were uniformly distributed. Mg2Ni/Mg2NiH4 and metallic V were formed in-situ during cycling, which synergistically tuned the hydrogen storage process in MgH2. Our work presents a facile interfacial engineering method to enhance the catalytic activity by constructing a heterostructure, which may provide the mentality of designing efficient catalysts for hydrogen storage. © 2022 Hydrogen Energy Publications LLC","Herein, nickel/vanadium trioxide (Ni/V2O3) nanoparticles with heterostructures were successfully prepared via hydrogenating the NiV-based two-dimensional layered double hydroxide (NiV-LDH). Mg2Ni/Mg2NiH4 and metallic V were formed in-situ during cycling, which synergistically tuned the hydrogen storage process in MgH2.",_
!086,"Hydrogen storage plays a pivotal role in the hydrogen industry, yet its current status presents a bottleneck. Diverse strategies have emerged in recent years to address this challenge. MgH2 has stood out as a promising solid-state hydrogen storage material due to its impressive gravimetric and volumetric hydrogen density, but its practical application is hampered by elevated thermal stability and sluggish kinetics. In this study, we introduce a solution by synthesizing Pd metallene through a one-pot solvothermal method, revealing a distinctive highly curved lamellar structure with a thickness of around 1.6 nm. Incorporating this Pd metallene into MgH2 results in a composite system wherein the starting dehydrogenation temperature is significantly lowered to 439 K and complete dehydrogenation occurs at 583 K, releasing 6.14 wt.% hydrogen. The activation energy of dehydrogenation for MgH2 was reduced from 170.4 kJ mol–1 to 79.85 kJ mol–1 after Pd metallene decoration. The enthalpy of dehydrogenation of the MgH2–10 wt.% Pd sample was calculated to be 73 kJ mol–1 H2 –1 and decreased by 4.4 kJ mol–1 H2 –1 from that of dehydrogenation of pure MgH2 (77.4 kJ mol–1 H2 –1). Theoretical calculations show that the average formation energy and average adsorption energy of hydrogen vacancies can be significantly reduced in the presence of both Pd clusters and Pd single atoms on the surface of MgH2/Mg, respectively. It suggests that the synergistic effect of in situ formed Pd single atoms and clusters significantly improves the hydrogenation and dehydrogenation kinetics. The identified active sites in this study hold potential as references for forthcoming multi-sized active site catalysts, underscoring a significant advancement toward resolving hydrogen storage limitations. © 2024","MgH2 has stood out as a promising solid-state hydrogen storage material due to its impressive gravimetric and volumetric hydrogen density, but its practical application is hampered by elevated thermal stability and sluggish kinetics. Incorporating this Pd metallene into MgH2 results in a composite system wherein the starting dehydrogenation temperature is significantly lowered to 439 K and complete dehydrogenation occurs at 583 K, releasing 6.14 wt.% hydrogen.",_
!087,"Magnesium hydride (MgH2) is the most feasible and effective solid-state hydrogen storage material, which has excellent reversibility but initiates decomposing at high temperatures and has slow kinetics performance. Here, zinc titanate (Zn2TiO4) synthesised by the solid-state method was used as an additive to lower the initial temperature for dehydrogenation and enhance the re/dehydrogenation behaviour of MgH2. With the presence of Zn2TiO4, the starting temperature for the dehydrogenation of MgH2 was remarkably lowered to around 290 °C–305 °C. In addition, within 300 s, the MgH2–Zn2TiO4 sample absorbed 5.0 wt.% of H2 and 2.2–3.6 wt.% H2 was liberated from the composite sample in 30 min, which is faster by 22–36 times than as-milled MgH2. The activation energy of the MgH2 for the dehydrogenation process was also downshifted to 105.5 kJ/mol with the addition of Zn2TiO4 indicating a decrease of 22% than as-milled MgH2. The superior behaviour of MgH2 was due to the formation of MgZn2, MgO and MgTiO3, which are responsible for ameliorating the re/dehydrogenation behaviour of MgH2. These findings provide a new understanding of the hydrogen storage behaviour of the catalysed-MgH2 system. © 2023","Magnesium hydride (MgH2) is the most feasible and effective solid-state hydrogen storage material, which has excellent reversibility but initiates decomposing at high temperatures and has slow kinetics performance. In addition, within 300 s, the MgH2–Zn2TiO4 sample absorbed 5.0 wt.% of H2 and 2.2–3.6 wt.% H2 was liberated from the composite sample in 30 min, which is faster by 22–36 times than as-milled MgH2.",_
!088,"The process of heat-driven mass transfer involved in hydrogen storage within metal hydrides (MHs) demands implementing a heat transfer system (HTS) to facilitate faster hydrogen charging and discharging. One effective method to enhance heat transfer is utilizing an HTS equipped with fins and a cooling tube. Among the crucial factors for optimizing the reactor, fin efficiency (FE) plays a vital role, although it has not been explored in unsteady processes like the present one. This study introduces a novel FE technique to optimize fins in a conventional longitudinal finned tube MH reactor based on LaNi5. Due to the intricacies of the problem, making analytical estimation of FE challenging, the authors turned to the concept of reverse engineering. This approach utilizes simulated data's temporal temperature profiles to calculate the FE. The number of fins is varied from 4 to 12 while keeping the total fin weight constant. Heat transfer performance improved as the number of fins increased, but the FE deteriorated from 0.89 to 0.56 due to the reduction in fin thickness. A performance index (PI) that considers the number of fins is introduced to assess the overall performance. Its values are 0.58, 0.79, 0.96, 1.05, and 1.1 for configurations with 4, 6, 8, 10, and 12 fins, respectively. The configuration with 8 fins is deemed optimal because further increasing the number of fins led to only marginal improvements in PI value. Subsequent optimization of fin shape, precisely radial tapering, had a minimal impact on heat transfer performance. Finally, the desorption behavior was examined for the optimal configuration with 8 fins of constant thickness. © 2023 Elsevier Ltd","One effective method to enhance heat transfer is utilizing an HTS equipped with fins and a cooling tube. Subsequent optimization of fin shape, precisely radial tapering, had a minimal impact on heat transfer performance.",_
!089,"Magnesium hydride (MgH2) has been under spot light recently when it comes to solid-state hydrogen storage media owing to its superior hydrogen storage capacity, reasonably good reversibility, and cost-effectiveness. Albeit these advantageous attributes, it suffers from the setback of having undesirably high thermodynamic stability and exceedingly sluggish kinetics, which diminishes its feasibility for practical use. The purview of this review article is to first introduce the basic understandings related to sorption kinetic of hydrogen storage material with a emphasis on MgH2 and to elucidate the key developments in the field of exploiting various kinds of Metal Oxide-based catalysts in improving the hydrogenation kinetics of MgH2. The article initiates with brief but sufficiently explanatory discussions on the rudiments of hydrogen sorption in MgH2 followed by an elaborate exposition on the usage of catalyst as a possible means to alleviate some of the shortcomings of the virgin compound. This article assesses a number of factors affecting the catalytic efficiency, e.g., defect density, valance state of the metal ion, oxygen vacancy, etc., which dictates the metal oxide-based catalysts as a prime candidate in this regard. A whole host of binary and ternary metal oxides have been taken under consideration to build up a coherent description of the reaction mechanism, reduction in the activation energy barrier, enhanced sorption rate, and other relevant parameters governing the kinetics of the reaction. The synergistic effect of two or more metal oxide-based catalysts has also been alluded to as this amalgamation of several catalysts has brought to bear a greater degree of enhancement compared to an individual application. This review concludes by delineating a scheme of plausible future modifications that can possibly augment the entire business of hydrogen sorption in Magnesium Hydride. At the end it is suggested that a complete understanding of reaction mechanism for kinetic enhanment is essential before developing more catalysts. A clear understanding will evolute a perfect catalyst that can be realized in practical utility. © 2023 Hydrogen Energy Publications LLC","Magnesium hydride (MgH2) has been under spot light recently when it comes to solid-state hydrogen storage media owing to its superior hydrogen storage capacity, reasonably good reversibility, and cost-effectiveness. Albeit these advantageous attributes, it suffers from the setback of having undesirably high thermodynamic stability and exceedingly sluggish kinetics, which diminishes its feasibility for practical use.",_
!090,"To explore more possibilities for hydrogen economy, Mg-based alloys containing long period stacking ordered (LPSO) phase for solid-state hydrogen storage deserve attention. In this paper, indium (In) element is adopted to alter the de/hydrogenation abilities of Mg–Y–Zn alloys. The relationship between microstructural features and hydrogen storage behaviors of Mg95Y3Zn2-xInx (x = 0, 1 and 2 at.%) alloys are discussed in detail. Indium element can modify the morphology of LPSO phase and more Mg interfaces are obtained. LPSO phase cannot be generated when Zn is completely replaced by In element; instead α-Mg grains and eutectic phase (Mg + MgYIn) the constitute the In2 alloy. Element In benefits the activation process of the alloys in this paper, which helps the alloy particles to be hydrogenated quickly in the first hydrogenation. Specifically, 1 at.% In substitution for Zn accelerates dehydrogenation and the dehydrogenation temperature reduces by 11 °C. The benefits of In element for dehydrogenation behaviors mainly come from increased Mg grain boundaries, larger MgH2 lattice constants with weaker Mg–H bonds, uniformly distributed nanoscale YH2/YH3 phase. © 2023 Hydrogen Energy Publications LLC","Indium element can modify the morphology of LPSO phase and more Mg interfaces are obtained. The benefits of In element for dehydrogenation behaviors mainly come from increased Mg grain boundaries, larger MgH2 lattice constants with weaker Mg–H bonds, uniformly distributed nanoscale YH2/YH3 phase.",_
!091,"Laves phase high-entropy alloys are considered as good candidates for hydrogen storage applications. However, they usually suffer from poor first hydrogenation kinetics, the so-called activation process. In this paper, we attempt to solve the activation problem of the Ti0.5Zr0.5(Mn1-xFex)Cr1 (x = 0, 0.2 and 0.4) by high-pressure torsion (HPT). The HPT process was carried out under 6 GPa pressure for 5 revolutions in air on samples synthesized by arc melting. The hydrogenation kinetics were measured using a Sievert's type apparatus at room temperature under 2 MPa of hydrogen pressure. While the as-cast alloys become totally inert to hydrogen after air exposure, the HPT-processed samples absorb 1.6–1.8 wt% of hydrogen at room temperature in a few seconds even after air exposure for 2 months. The easy activation of alloys processed by HPT is due to the formation of lattice defects that act as nucleation points. These results confirm that HPT processing is an effective strategy to develop active hydrogen storage materials. © 2023 Elsevier B.V.",The HPT process was carried out under 6 GPa pressure for 5 revolutions in air on samples synthesized by arc melting. The hydrogenation kinetics were measured using a Sievert's type apparatus at room temperature under 2 MPa of hydrogen pressure.,_
!092,"The low-cost production, safe storage and transportation, and efficient application of hydrogen are the focus of the current hydrogen energy researches. Among them, safe and efficient storage and transportation is the technical key to the large-scale application of hydrogen energy, so the research and development of high-capacity solid hydrogen storage materials have both academic significance and application value. Hydrogen storage by solid material has become the most promising hydrogen storage technology due to its large storage density and high safety factor, which has received widespread attention from researchers. In this paper, according to the current research status of solid hydrogen storage materials, the research progress of several solid hydrogen storage materials is discussed, including those based on physical adsorption, metal, coordinated hydride and hydrate. The most promising magnesium-based hydrogen storage materials are re-evaluated, and the effects of several modification methods such as alloying, nano-anodization, adding catalysts, and composite light metal coordination hydrides on the hydrogen storage mechanism, microstructure, thermodynamic properties and kinetic properties of magnesium-based hydrogen storage materials are elaborated. The integrated design considering production, storage and use of hydrogen should be the development trend for the industrialization of solid hydrogen storage. © 2023 Chemical Industry Press. All rights reserved.","In this paper, according to the current research status of solid hydrogen storage materials, the research progress of several solid hydrogen storage materials is discussed, including those based on physical adsorption, metal, coordinated hydride and hydrate. The most promising magnesium-based hydrogen storage materials are re-evaluated, and the effects of several modification methods such as alloying, nano-anodization, adding catalysts, and composite light metal coordination hydrides on the hydrogen storage mechanism, microstructure, thermodynamic properties and kinetic properties of magnesium-based hydrogen storage materials are elaborated.",_
!093,"Hydrogen energy is a key role in novel renewable energy production/consumption technologies. Traditional hydrogen energy systems are suffered from low density, high production cost, low efficiency, and storage complications. With the start of solid-state hydrogen storage technology, many of above deficiencies are fulfilled, however, there are several unknown points, particularly in metal oxides, which need more attention. Hydrogen sorption on the layered materials or inside porous materials is a hopeful key to drawbacks for high-performance hydrogen sorption. Hereupon, layered solids with the merit of hydrogen sorption are introduced, for the first time, including “nanostructured bi-metal oxide (BMO)” and “graphitic carbon nitride (CN)”. Perovskites are ceramic and they are hard materials so they could be a favorable candidate for solid-state hydrogen storage. g-C3N4 has attractive features including high surface area, chemical stability, small band gap, and low-cost synthesis methods but also has great potential as an electrode material for energy storage capacitors. The main motivation for this study comes from the potential applications for perovskite materials and graphitic carbon nitride for the solid-state hydrogen storage method. The Perovskite type GdFeO3 nanostructures (as BMO) synthesized through sol-gel approach in front of natural source of Grape juice as both complexing agent and fuel. The experimental scrutinization ascertains an original fabrication of GdFeO3 (GF) nanostructures in Grape juice at 800 °C, with an approximately uniform nanosized structure of 70 nm on average. The obtained pure GF nanostructures are then utilized for nanocomposite formation based on g-C3N4 (CN) with different amounts. The resulting nanocomposites with the ratio of 1:2 from GF:CN perform a preferable hydrogen sorption capacity, in terms of “maximum discharge capacity of 577 mAhg−1” in 2 M KOH electrolyte. It should be declared that however, the discharge capacity of the nanostructured GF is 188 mAhg−1. It can be emphasized that these GF/CN nanocomposites can be utilized as hopeful hosts in an electrochemical hydrogen storage setup due to the synergic effect of g-C3N4 with essential characteristics in cooperation with BMO nanostructures as acceptable electrocatalysts. © 2022 Hydrogen Energy Publications LLC",The obtained pure GF nanostructures are then utilized for nanocomposite formation based on g-C3N4 (CN) with different amounts. It can be emphasized that these GF/CN nanocomposites can be utilized as hopeful hosts in an electrochemical hydrogen storage setup due to the synergic effect of g-C3N4 with essential characteristics in cooperation with BMO nanostructures as acceptable electrocatalysts.,_
!094,"We develop a continuum framework applicable to solid-state hydrogen storage, cell biology and other scenarios where the diffusion of a single constituent within a bulk region is coupled via adsorption/desorption to reactions and diffusion on the boundary of the region. We formulate content balances for all relevant constituents and develop thermodynamically consistent constitutive equations. The latter encompass two classes of kinetics for adsorption/desorption and chemical reactions - fast and Marcelin-De Donder, and the second class includes mass action kinetics as a special case. We apply the framework to derive a system consisting of the standard diffusion equation in bulk and FitzHugh-Nagumo type surface reaction-diffusion system of equations on the boundary. We also study the linear stability of a homogeneous steady state in a spherical region and establish sufficient conditions for the occurrence of instabilities driven by surface diffusion. These findings are verified through numerical simulations which reveal that instabilities driven by diffusion lead to the emergence of steady-state spatial patterns from random initial conditions and that bulk diffusion can suppress spatial patterns, in which case temporal oscillations can ensue. We include an extension of our framework that accounts for mechanochemical coupling when the bulk region is occupied by a deformable solid. This article is part of the theme issue 'Foundational issues, analysis and geometry in continuum mechanics'. © 2023 The Authors.","These findings are verified through numerical simulations which reveal that instabilities driven by diffusion lead to the emergence of steady-state spatial patterns from random initial conditions and that bulk diffusion can suppress spatial patterns, in which case temporal oscillations can ensue. We include an extension of our framework that accounts for mechanochemical coupling when the bulk region is occupied by a deformable solid.",_
!095,"Catalyst-modified magnesium hydride (MgH2) holds the greatest promise as a solid-state hydrogen storage medium for mobile and stationary applications. However, the design and fabrication of highly active catalysts that enable MgH2 to reversibly desorb/absorb a large amount of hydrogen still remains challenging. In this work, a novel nanostructured ZrFe2 (nano-ZrFe2) measuring 30-120 nm in size was designed and fabricated as a catalyst precursor, which was readily converted into ultrafine ZrH2 and metallic Fe nanoparticles upon ball milling with MgH2 and first de-/hydrogenation, consequently delivering quite high catalytic activity for hydrogen storage in MgH2. MgH2 containing 10 wt% nano-ZrFe2 desorbed 6.2 wt% of H2 starting from approximately 193 °C, which was lowered by 35 °C with respect to the micron-ZrFe2-modified MgH2 (∼228 °C). When operated at a hydrogen pressure of 50 bars, the dehydrogenated sample absorbed ∼5.3 wt% of H2 at 200 °C within 30 minutes. The remarkably improved kinetic properties of MgH2 are mainly attributed to the ultrasmall nanoparticles and uniform, dispersive distribution of in situ formed ZrH2 and Fe. Such in situ conversion of nano-ZrFe2 not only provided a multiphase and multiscale catalytic environment that enabled high reactivity and catalytic activity but also facilitated H diffusion owing to increased interfaces, consequently promoting the dissociation and recombination of H2 molecules. These important insights in the new nanoscaled intermetallics broaden the scope of the design and synthesis of much higher active catalysts for hydrogen storage in light-metal hydrides, especially in MgH2 © 2024 The Royal Society of Chemistry.","Catalyst-modified magnesium hydride (MgH2) holds the greatest promise as a solid-state hydrogen storage medium for mobile and stationary applications. In this work, a novel nanostructured ZrFe2 (nano-ZrFe2) measuring 30-120 nm in size was designed and fabricated as a catalyst precursor, which was readily converted into ultrafine ZrH2 and metallic Fe nanoparticles upon ball milling with MgH2 and first de-/hydrogenation, consequently delivering quite high catalytic activity for hydrogen storage in MgH2.",_
!096,"In this paper, using density functional theory (DFT), we investigate the impact of mechanical treatment in terms of uniaxial and biaxial strains on both hydrogenation states of magnesium compounds i.e. H2-free magnesium (Mg) and preliminarily hydrogenated magnesium (MgH2). The thermodynamic properties calculation shows that applying uniaxial and biaxial strains on the H2-free magnesium does not significantly affect the formation enthalpy and decomposition temperature of the hydride phase. On the other hand, strain energy contributions on preliminarily hydrogenated magnesium are found able to decrease and improve the formation enthalpy and the decomposition temperature, making it feasible for the operational conditions of proton exchange membrane (PEM) fuel cells at 289 – 393 K. Also, the findings demonstrate that the kinetic properties in terms of hydrogen atom diffusion show a decrease in the activation energy barrier, which means an improvement in the kinetics properties faster than that of strain-free magnesium hydride. These results potentially provide better clues for the development of a magnesium-based metal hydride for hydrogen storage applications. © 2023 Hydrogen Energy Publications LLC","In this paper, using density functional theory (DFT), we investigate the impact of mechanical treatment in terms of uniaxial and biaxial strains on both hydrogenation states of magnesium compounds i.e. H2-free magnesium (Mg) and preliminarily hydrogenated magnesium (MgH2). These results potentially provide better clues for the development of a magnesium-based metal hydride for hydrogen storage applications.",_
!097,"Magnesium hydrides (MgH2) have drawn a lot of interest as a promising hydrogen storage material option due to their good reversibility and high hydrogen storage capacity (7.60 wt.%). However, the high hydrogen desorption temperature (more than 400 °C) and slow sorption kinetics of MgH2 are the main obstacles to its practical use. In this research, nickel zinc oxide (Ni0.6Zn0.4O) was synthesized via the solid-state method and doped into MgH2 to overcome the drawbacks of MgH2. The onset desorption temperature of the MgH2–10 wt.% Ni0.6Zn0.4O sample was reduced to 285 °C, 133 °C, and 56 °C lower than that of pure MgH2 and milled MgH2, respectively. Furthermore, at 250 °C, the MgH2–10 wt.% Ni0.6Zn0.4O sample could absorb 6.50 wt.% of H2 and desorbed 2.20 wt.% of H2 at 300 °C within 1 h. With the addition of 10 wt.% of Ni0.6Zn0.4O, the activation energy of MgH2 dropped from 133 kJ/mol to 97 kJ/mol. The morphology of the samples also demonstrated that the particle size is smaller compared with undoped samples. It is believed that in situ forms of NiO, ZnO, and MgO had good catalytic effects on MgH2, significantly reducing the activation energy and onset desorption temperature while improving the sorption kinetics of MgH2. © 2023 by the authors.","Magnesium hydrides (MgH2) have drawn a lot of interest as a promising hydrogen storage material option due to their good reversibility and high hydrogen storage capacity (7.60 wt.%). It is believed that in situ forms of NiO, ZnO, and MgO had good catalytic effects on MgH2, significantly reducing the activation energy and onset desorption temperature while improving the sorption kinetics of MgH2.",_
!098,"Hydrogen as an energy carrier has shown promises for future energy infrastructure. Due to its light weight and explosive nature, hydrogen need to be stored in safe and efficient way. The storage in solid state materials has been proposed as the safest method, which can store hydrogen through chemical bonding. Among several studied materials so far, KSiH3 is one of the leading contender with a total hydrogen capacity of 4.3 wt %, which is more than what is offered by its rivals such as BCC hydrides or AB5 type hydrides. However, the high activation energy slows down the hydrogen charging/discharging rate and allow the working only at higher temperatures (∼200 °C). The kinetics of hydrogen absorption and desorption intensely improved by the addition of a catalyst. In this work, vanadium based catalysts are added to KSiH3 system to modify the surface and to enhance the kinetics of this system. Specially, V2O5 addition, as leading candidate among the studied catalyst, decreased the activation energy to 83 kJmol-1 from 142 kJ/mol for pristine KSi. KSiH3 system with catalyst V2O5 started desorbing at 100 °C and could achieve highest weight loss 3.7 wt % which is very close to theoretical value. No disproportionation phenomenon is detected which indicated that the reaction between KSiH3 and KSi is flawlessly reversible with a hydrogen storage capacity of 3.7 wt % H2. The XPS investigation suggested a partial reduction of +5 oxidation state (corresponding to V2O5) to metallic state, which is proposed as the possible cause of this improvement. © 2022 Hydrogen Energy Publications LLC","KSiH3 system with catalyst V2O5 started desorbing at 100 °C and could achieve highest weight loss 3.7 wt % which is very close to theoretical value. The XPS investigation suggested a partial reduction of +5 oxidation state (corresponding to V2O5) to metallic state, which is proposed as the possible cause of this improvement.",_
!099,"Although MgH2 has been widely regarded as a promising material for solid-state hydrogen storage, its high operating temperature and slow kinetics pose a major bottleneck to its practical application. Here, a nanocomposite catalyst with interfacial coupling and oxygen defects, Ni/CeO2, is fabricated to promote H2 desorption and absorption properties of MgH2. The interface of Ni/CeO2 contributes to both strong mechanical coupling towards stabilizing partial Ni and electronic coupling towards inducing a high concentration of oxygen vacancies in CeO2. Theoretical calculations evidence that CeO2 with oxygen vacancy assist Ni in weakening the energy of Mg-H bond as well as enhancing the adsorption energy of Ni upon hydrogen atoms, and the extent of this assistance surprisingly increases with increasing oxygen vacancies concentration. As a result, an impressive performance is achieved by MgH2-5 wt.% Ni/CeO2 with onset desorption temperature of only 165 °C, and it absorbs approximately 80% hydrogen in just 800 s at 125 °C. The generation mechanism of intermediate active species concerning Ni/CeO2 in different states has been analyzed for the first time, and the relationship between interfacial coupling and phase evolution has been elucidated. Therefore, a mechanism of the catalysis-assisting effect regarding oxygen defects is proposed. It is believed that this work provides a unique perspective on the mechanism of interfacial coupling and the generation of defects in composite catalysts. © 2023","As a result, an impressive performance is achieved by MgH2-5 wt.% Ni/CeO2 with onset desorption temperature of only 165 °C, and it absorbs approximately 80% hydrogen in just 800 s at 125 °C. Therefore, a mechanism of the catalysis-assisting effect regarding oxygen defects is proposed.",_
!100,"LiAlH4 is considered as a promising material for solid state hydrogen storage. However, the lack of reversibility along with sluggish kinetics hinders its practical application. In this paper, hollow carbon nanospheres (HCNs) were used as a porous scaffold to confine LiAlH4 via solvent impregnation method. Nanoconfined LiAlH4 (LiAlH4@HCNs) exhibited significant improvements in hydrogen sorption compared to its bulk counterpart. LiAlH4@HCNs releases hydrogen sharply at 146 °C with full conversion to LiH within 1.5 h. The desorbed material can also be regenerated back to some extent into LiAlH4 under 8 MPa H2 at 150 °C. Measurement of the pressure-composition isotherm suggests an alteration in the equilibrium state upon confinement of LiAlH4 in voids of a few nanometres and thus altered hydrogen thermodynamic paths. © 2022 Elsevier B.V.","However, the lack of reversibility along with sluggish kinetics hinders its practical application. In this paper, hollow carbon nanospheres (HCNs) were used as a porous scaffold to confine LiAlH4 via solvent impregnation method.",_
!101,"This study aims to present the hydro-catalytic treatment of organoamine boranes for efficient thermal dehydrogenation for hydrogen production. Organoamine boranes, methylamine borane (MeAB), and ethane 1,2 diamine borane (EDAB), known as ammonia borane (AB) carbon derivatives, are synthesized to be used as a solid-state hydrogen storage medium. Thermal dehydrogenation of MeAB and EDAB is performed at 80 °C, 100 °C, and 120 °C under different conditions (self, catalytic, and hydro-catalytic) for hydrogen production and compared with AB. For this purpose, a cobalt-doped activated carbon (Co-AC) catalyst is fabricated. The physicochemical properties of Co-AC catalyst is investigated by well-known techniques such as ATR/FT-IR, XRD, XPS, ICP-MS, BET, and TEM. The synthesized Co-AC catalyst obtained in nano CoOOH structure (20 nm, 12% Co wt) is formed and well-dispersed on the activated carbon support. It has indicated that Co-AC exhibits efficient catalytic activity towards organoamine boranes thermal dehydrogenation. Hydrogen release tests show that hydro-catalytic treatment improves the thermal dehydrogenation kinetics of neat MeAB, EDAB, and AB. Co-AC catalyzed hydro-treatment for thermal dehydrogenation of MeAB and EDAB acceleras the hydrogen release from 0.13 mL H2/min to 46.12 mL H2/min, from 0.16 mL H2/min to 38.06 mL H2/min, respectively at 80 °C. Moreover, hydro-catalytic treatment significantly lowers the H2 release barrier of organoamine boranes thermal dehydrogenation, from 110 kJ/mol to 19 kJ/mol for MeAB and 130 kJ/mol to 21 kJ/mol for EDAB. In conclusion, hydro and catalytic treatment presents remarkable synergistic effect in thermal dehydrogenation and improves the hydrogen release kinetics. © 2021 Hydrogen Energy Publications LLC","The physicochemical properties of Co-AC catalyst is investigated by well-known techniques such as ATR/FT-IR, XRD, XPS, ICP-MS, BET, and TEM. Hydrogen release tests show that hydro-catalytic treatment improves the thermal dehydrogenation kinetics of neat MeAB, EDAB, and AB.",_
!102,"Solid-state hydrogen storage based on metal hydrides is considered a promising method for hydrogen storage. However, the low inherent thermal conductivity of metal hydride powder significantly limits the hydrogenation/dehydrogenation process in the metal hydride bed. Accurate measurement and improvement of the effective thermal conductivity of a hydride bed is of great significance for design of solid-state hydrogen storage devices. This article analyzes the factors that influence the effective thermal conductivity of a metal hydride bed, and also introduces different measurement methods and improvement ways for the effective thermal conductivity of a metal hydride bed. It is an effective way to improve the thermal conductivity of metal hydride beds by hydride powder mixed with a high thermal conductivity material and compaction. Accurately measuring the influence of hydrogen pressure, temperature and hydrogen storage capacity and other factors on the effective thermal conductivity of a metal hydride bed and obtaining the numerical equation of effective thermal conductivity play an important role in guiding the optimization design of heat and mass transfer structure of metal hydride hydrogen storage devices. The transient plane source method seems to be a better measurement choice because of short test time and easy to establish a pressure-tight and temperature control test system. However, there is still a lack of testing standards for the thermal conductivity of the hydride bed, as well as suggestions for the selection of test methods, improvement ways and design of in situ test room. © 2022 The Royal Society of Chemistry.",It is an effective way to improve the thermal conductivity of metal hydride beds by hydride powder mixed with a high thermal conductivity material and compaction. The transient plane source method seems to be a better measurement choice because of short test time and easy to establish a pressure-tight and temperature control test system.,_
!103,"Humanity is confronted with one of the most significant challenges in its history. The excessive use of fossil fuel energy sources is causing extreme climate change, which threatens our way of life and poses huge social and technological problems. It is imperative to look for alternate energy sources that can replace environmentally destructive fossil fuels. In this scenario, hydrogen is seen as a potential energy vector capable of enabling the better and synergic exploitation of renewable energy sources. A brief review of the use of hydrogen as a tool for decarbonizing our society is given in this work. Special emphasis is placed on the possibility of storing hydrogen in solid-state form (in hydride species), on the potential fields of application of solid-state hydrogen storage, and on the technological challenges solid-state hydrogen storage faces. A potential approach to reduce the carbon footprint of hydrogen storage materials is presented in the concluding section of this paper. © 2021 by the author.",Humanity is confronted with one of the most significant challenges in its history. It is imperative to look for alternate energy sources that can replace environmentally destructive fossil fuels.,_
!104,"LiBH4 as a promising candidate material for solid-state hydrogen storage still suffers from high dehydrogenation temperature and poor reversibility. A catalyzed LiBH4-based system with in situ introduced Li3BO3 and V is synthesized by adding NH4VO3 into LiBH4 followed by a heat treatment and a hydrogenation process. The optimized LiBH4 system introduced with 0.06 molar fraction of Li3BO3 + V, which is denoted as LiBH4–0.06LiBOV, shows excellent hydrogen storage kinetics and high reversible stability. The system starts to release hydrogen at 220 °C, and a capacity of 5.8 wt % H2 is obtained at 350 °C within 90 min. Furthermore, full rehydrogenation can be achieved at 500 °C and 50 bar of H2 for 50 min, and a capacity retention as high as 87.5% is obtained after five cycles. In situ introduced Li3BO3 and V lower the activation energy of LiBH4 and inhibit the generation of Li2B12H12 during the hydrogenation of LiBH4, which contribute to the synergistic catalytic effects on hydrogen desorption and absorption. In addition, the restraining of the particle size growth during dehydrogenation/hydrogenation is critical to inhibiting the generation of Li2B12H12 and thus improves the hydrogenation property of LiBH4. The catalyzed LiBH4 system provides new insights on LiBH4 as a high-density hydrogen storage material. © 2022 American Chemical Society","LiBH4 as a promising candidate material for solid-state hydrogen storage still suffers from high dehydrogenation temperature and poor reversibility. The optimized LiBH4 system introduced with 0.06 molar fraction of Li3BO3 + V, which is denoted as LiBH4–0.06LiBOV, shows excellent hydrogen storage kinetics and high reversible stability.",_
!105,"Metallic hydride clusters have greater importance due to its unique physicomechanical properties. For solid-state hydrogen storage, (HfH2)n clusters has been considered a promising candidate because of high hydrogen capacity, low cost and larger interacting affinity between atoms. The structural and electronic properties of (HfH2)n clusters are investigated by employing the density functional theory. From the DFT calculations, it is found that Hf atom occupies central position while H atoms tends to occupy at vertex spots. Through structural stability analysis, the calculated binding energy and second order energy difference of (HfH2)n clusters increases from (HfH2)5 through (HfH2)30. The charge density distribution and results of Bader analysis revealed ionic bonding character between Hf and H atoms and transfer of electrons is observed from Hf to H atoms. The orbital overlapping contribution of the interacting Hf and H atom is also performed. © 2021 Elsevier B.V.","Metallic hydride clusters have greater importance due to its unique physicomechanical properties. From the DFT calculations, it is found that Hf atom occupies central position while H atoms tends to occupy at vertex spots.",_
!106,"A ball milling technique was used to prepare a 4MgH2-LiAlH4 doped TiO2 sample. The hydrogen storage behaviour of the system 4MgH2-LiAlH4-TiO2 and the role played by TiO2 have been systematically investigated. The result shows the decrement of the initial decomposition temperature from the 4MgH2-LiAlH4-TiO2 composite when contrasted with the 4MgH2-LiAlH4 system. The initial dehydrogenation temperature of 4MgH2-LiAlH4-10 wt% TiO2 destabilized system decreased from 100°C and 270°C of undoped composite to 70°C and 200°C, respectively, for the desorption process in the first two stages. It was also found that the re/dehydrogenation kinetics performances of the 4MgH2-LiAlH4-10 wt% TiO2 destabilized system was improved when contrasted with the non-catalyzed sample. On the other hand, the activation energy for the MgH2-relevant decomposition is reduced from 133.3 kJ/mol (4MgH2-LiAlH4 sample) to 102.5 kJ/mol (4MgH2-LiAlH4-TiO2 sample). In addition, this synergistic effect of TiO2 on the improvement of the absorption/desorption performances was related to the formation of Al3Ti and TiH2 phases in the doped sample upon desorption, which reinforces the interaction of MgH2 with LiAlH4. This further changes the thermodynamics of the reactions by modifying the absorption/desorption pathway. In conclusion, the TiO2 catalyst showed a good catalytic impact in ameliorating the hydrogen sorption behaviour of the 4MgH2-LiAlH4 sample. © 2021 John Wiley & Sons Ltd","The initial dehydrogenation temperature of 4MgH2-LiAlH4-10 wt% TiO2 destabilized system decreased from 100°C and 270°C of undoped composite to 70°C and 200°C, respectively, for the desorption process in the first two stages. It was also found that the re/dehydrogenation kinetics performances of the 4MgH2-LiAlH4-10 wt% TiO2 destabilized system was improved when contrasted with the non-catalyzed sample.",_
!107,"Hydrogen energy is a very attractive option in dealing with the existing energy crisis. For the development of a hydrogen energy economy, hydrogen storage technology must be improved to over the storage limitations. Compared with traditional hydrogen storage technology, the prospect of hydrogen storage materials is broader. Among all types of hydrogen storage materials, solid hydrogen storage materials are most promising and have the most safety security. Solid hydrogen storage materials include high surface area physical adsorption materials and interstitial and non-interstitial hydrides. Among them, interstitial hydrides, also called intermetallic hydrides, are hydrides formed by transition metals or their alloys. The main alloy types are A2B, AB, AB2, AB3, A2B7, AB5, and BCC. A is a hydride that easily forms metal (such as Ti, V, Zr, and Y), while B is a non-hydride forming metal (such as Cr, Mn, and Fe). The development of intermetallic compounds as hydrogen storage materials is very attractive because their volumetric capacity is much higher (80-160 kgH2m-3) than the gaseous storage method and the liquid storage method in a cryogenic tank (40 and 71 kgH2m-3). Additionally, for hydrogen absorption and desorption reactions, the environmental requirements are lower than that of physical adsorption materials (ultra-low temperature) and the simplicity of the procedure is higher than that of non-interstitial hydrogen storage materials (multiple steps and a complex catalyst). In addition, there are abundant raw materials and diverse ingredients. For the synthesis and optimization of intermetallic compounds, in addition to traditional melting methods, mechanical alloying is a very important synthesis method, which has a unique synthesis mechanism and advantages. This review focuses on the application of mechanical alloying methods in the field of solid hydrogen storage materials. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.","Additionally, for hydrogen absorption and desorption reactions, the environmental requirements are lower than that of physical adsorption materials (ultra-low temperature) and the simplicity of the procedure is higher than that of non-interstitial hydrogen storage materials (multiple steps and a complex catalyst). In addition, there are abundant raw materials and diverse ingredients.",_
!108,"Ordered mesoporous carbon materials offer robust network of organized pores for energy storage and catalysis applications, but suffer from time-consuming and intricate preparations hindering their widespread use. Here we report a new and rapid synthetic route for a N-doped ordered mesoporous carbon structure through a preferential heating of iron oxide nanoparticles by microwaves. A nanoporous covalent organic polymer is first formed in situ covering the hard templates of assembled nanoparticles, paving the way for a long-range order in a carbonaceous nanocomposite precursor. Upon removal of the template, a well-defined cubic mesoporous carbon structure was revealed. The ordered mesoporous carbon was used in solid state hydrogen storage as a host scaffold for NaAlH4, where remarkable improvement in hydrogen desorption kinetics was observed. The state-of-the-art lowest activation energy of dehydrogenation as a single step was attributed to their ordered pore structure and N-doping effect. © 2021 Wiley-VCH GmbH","Upon removal of the template, a well-defined cubic mesoporous carbon structure was revealed. The state-of-the-art lowest activation energy of dehydrogenation as a single step was attributed to their ordered pore structure and N-doping effect.",_
!109,"Hydrogen storage materials with high hydrogen capacity and low operating temperature had attracted intense interests for solid state hydrogen storage application. Sodium alanate (NaAlH4) with suitable thermodynamics and relatively high capacity was one of the most promising hydrogen storage materials for practical applications. However, high kinetic barriers induced high operating temperature, slow hydrogen release/uptake rate and poor reversibility. Considerable studies revealed that the addition of Ti-based catalysts could effectively improve its kinetic performance, consequently reducing the de-/hydrogenation temperature and enhancing the hydrogen storage reversibility. In this work, recent research progress of hydrogen storage properties of NaAlH4 modified by Ti-based catalysts was reviewed to guide the future development of this hydrogen storage system. First, the doping methods of Ti-based catalysts were introduced. After that, the improvement in hydrogen storage performance of NaAlH4 with various Ti-based catalysts was summarized and the corresponding catalytic mechanisms were elucidated. Finally, the future research direction of catalyst-modified NaAlH4 was discussed. It was well known that the addition process of catalysts was closely related to its existing state and distribution in metal hydride matrix, which affected the catalytic functions. High-energy ball milling treatment not only reduced the particle sizes of catalysts and NaAlH4 but also increased the uniform distribution of catalysts and intimate contact with NaAlH4 caused by energetic collision between milling balls. This facilitated the high catalytic activity. As a result, high-energy ball milling was the most frequently used and effective preparation strategy for catalyst-modified NaAlH4-based hydrogen storage materials. For optimizing catalysts, a variety of Ti-based compounds, including Ti-based organic compounds, halides, oxides and intermetallics, were studied and evaluated for their catalytic activity. Their effects on hydrogen storage behaviors of NaAlH4 were compared and the corresponding mechanisms were discussed and revealed. In particular, NaAlH4 catalyzed with ultrafine Ti nanoparticles supported on carbon displayed the best overall hydrogen storage properties. The usable hydrogen capacity remained at 5.07% and the on-set dehydrogenation temperature was reduced to 75℃. The dehydrogenated sample was fully hydrogenated within 3 min at 100℃ and 12.2 MPa of hydrogen pressure. More importantly, the capacity retention was as high as 98.6% after 100 cycles, which is quite favorable for practical applications. In addition, mechanistic studies revealed that high valent Ti-based compounds were reduced to low valent species and finally gave rise to the formation of Al-Ti or TiHx due to the strong reductivity of NaAlH4 during ball milling and initial dehydrogenation/hydrogenation cycling. The Al-Ti or TiHx species work as the actual active catalysts to promote the breaking and recombination of Al-H bonding. This was the most important reason for the reduced operating temperatures of dehydrogenation/hydrogenation. The key role played by Ti-based catalysts in the reduction of kinetic energy barriers for hydrogen release from NaAlH4 was further confirmed by theoretical calculations. The future studies should mainly focus on the synergistic effects of nanostructing and nano-catalysis to further improve the overall hydrogen storage properties of NaAlH4 materials. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.","Sodium alanate (NaAlH4) with suitable thermodynamics and relatively high capacity was one of the most promising hydrogen storage materials for practical applications. As a result, high-energy ball milling was the most frequently used and effective preparation strategy for catalyst-modified NaAlH4-based hydrogen storage materials.",_
!110,"The research progress of solid-state hydrogen storage technology is reviewed, including hydrogen storage materials, hydrogen storage devices and application status. Some hydrogen storage alloys have been successfully used in solid-state hydrogen storage devices. The high-capacity reversible hydrogen storage materials under mild hydrogen absorption and desorption conditions is the focus of current research and development. The optimized design of the hydrogen storage device effectively improves the rapid heat transfer characteristics and the safety performance. Hydrogen storage devices have been applied in the fields of distributed energy supply and motor vehicles. However, it is still necessary to further realize the coordination of rapid response, safety, reliability, and high hydrogen storage density of the hydrogen storage system. © 2022, Solar Energy Periodical Office Co., Ltd. All right reserved.","Hydrogen storage devices have been applied in the fields of distributed energy supply and motor vehicles. However, it is still necessary to further realize the coordination of rapid response, safety, reliability, and high hydrogen storage density of the hydrogen storage system.",_
!111,"Reversible solid-state hydrogen storage is one of the key technologies toward pollutant-free and sustainable energy conversion. The composite system LiBH4-MgH2 can reversibly store hydrogen with a gravimetric capacity of 13 wt%. However, its dehydrogenation/hydrogenation kinetics is extremely sluggish (∼40 h) which hinders its usage for commercial applications. In this work, the kinetics of this composite system is significantly enhanced (∼96%) by adding a small amount of NbF5. The catalytic effect of NbF5 on the dehydrogenation/hydrogenation process of LiBH4-MgH2 is systematically investigated using a broad range of experimental techniques such as in situ synchrotron radiation X-ray powder diffraction (in situ SR-XPD), X-ray absorption spectroscopy (XAS), anomalous small angle X-ray scattering (ASAXS), and ultra/small-angle neutron scattering (USANS/SANS). The obtained results are utilized to develop a model that explains the catalytic function of NbF5 in hydrogen release and uptake in the LiBH4-MgH2 composite system. This journal is  © The Royal Society of Chemistry.",Reversible solid-state hydrogen storage is one of the key technologies toward pollutant-free and sustainable energy conversion. The composite system LiBH4-MgH2 can reversibly store hydrogen with a gravimetric capacity of 13 wt%.,_
!112,"Hydrogen storage technology plays an important role on the development of hydrogen fuel cell and lithium aluminum hydride is a powerful candidate for solid-state hydrogen storage materials. However, the high stability and slow dehydrogenation kinetics of LiAlH4 hinder its application. In this paper, the two-step thermal decomposition properties of LiAlH4 with and without Fe–Fe2O3 catalysts are investigated. According to the master plots, the model of mample power law (Pn) and nucleation and growth (An) are the optimal mechanism functions for the two-step decomposition of LiAlH4, respectively. After doping catalysts, the activation energies decrease significantly. The theoretical and optimized kinetic method are consistent with each other on activation energy. And the latter can also yield other kinetic parameters for a more comprehensive kinetic modelling of LiAlH4 decomposition. Furthermore, Fe–Al2O3 and Fe–Al intermetallics generated during dehydrogenation might significantly improve the hydrogen release properties of LiAlH4. © 2022","In this paper, the two-step thermal decomposition properties of LiAlH4 with and without Fe–Fe2O3 catalysts are investigated. Furthermore, Fe–Al2O3 and Fe–Al intermetallics generated during dehydrogenation might significantly improve the hydrogen release properties of LiAlH4.",_
!113,"To run a sustainable society, hydrogen is considered as one of the most reliable option for clean and carbon free energy carrier. Hydrogen can be produced through several means using renewable energy sources, and can be stored either in solid, liquid or gaseous state. Though, compressed and liquefied hydrogen storages are well-established technologies in the commercial sector, however, due to the leakage risk, boil-off losses and explosive nature, world is exploring a safer way of hydrogen storage i.e. absorption/adsorption based solid-state hydrogen storage technology. The present review focuses mainly on the different material options available for the absorption based solid state hydrogen storage technology. The study reports insight view of different absorption material, broadly classified as metal hydrides and complex hydrides, with their hydrogen storage and reversible characteristics. The review also reports the tailoring properties of different hydrogen storage alloys and effect of element substitution on the absorption/desorption characteristics of a particular alloy. Key issues like effect of ball milling, annealing, doping, grain size, etc., on the alloy synthesis have been addressed. The review broadly summarizes the progress and recent worldwide advancement in the absorption based solid state hydrogen storage materials, synthesis and their hydrogenation/dehydrogenation mechanisms. © 2022 Elsevier Ltd","To run a sustainable society, hydrogen is considered as one of the most reliable option for clean and carbon free energy carrier. Key issues like effect of ball milling, annealing, doping, grain size, etc., on the alloy synthesis have been addressed.",_
!114,"A 10 kg alloy mass metal hydride reactor, with LaNi5 alloy was designed. Heat transfer enhacement in the reactor was achieved by including embedded cooling tubes and an external water jacket. Detailed parametric study has been carried to understand the performance of the system. The effect of both geometrical and operational parameters was studied in simulations. The optimized geometrical parameters were used for fabricating the reactor. Experimental studies were carried on the fabricated reactor. Absorption studies were carried out for different supply pressure and different cooling fluid temperatures. Storage capacity of 1.13 wt% was found in 1620 s at a supply pressure of 25 bar and with a flow rate of 20 LPM. Similarily, desorption studies were carried out for varying heat transfer fluid temperatures. Complete and fastest desorption was observed at 80 °C with the reaction completion time of 2700 s. © 2020 Hydrogen Energy Publications LLC",Heat transfer enhacement in the reactor was achieved by including embedded cooling tubes and an external water jacket. Complete and fastest desorption was observed at 80 °C with the reaction completion time of 2700 s. © 2020 Hydrogen Energy Publications LLC,_
!115,"Sluggish sorption kinetics, high decomposition temperature and unsatisfactory cycles of hydrogen release and uptake (reversibility) remain big challenges for using sodium alanate (NaAlH4) as a practical hydrogen storage medium. In solid-state hydrogen storage materials, especially NaAlH4, finding effective catalysts and using mechanical treatment represent promising solutions to overcome the drawbacks of NaAlH4. For the first time, in this work, the influence of spherical strontium titanate (SrTiO3) on the dehydrogenation behavior of NaAlH4 has been investigated. Here, we report that the onset desorption temperature is decreased and the desorption kinetics of NaAlH4 is enhanced with the addition of 10 wt% of spherical SrTiO3 catalyst. Using Kissinger's technique, the apparent activation energy of the NaAlH4 doped with 10 wt% SrTiO3 composites for the two-step dehydrogenation was identified as 79 and 92 kJ/mol, which was decreased significantly from that of undoped NaAlH4 (116 and 122 kJ/mol, respectively). Scanning electron microscopy results indicated that the NaAlH4 particle sizes decreased by milling with SrTiO3. X-ray diffraction results indicated that SrTiO3 did not react or change during the milling and desorption (heating) processes. The improvements in the desorption properties of NaAlH4 resulted from the ability of SrTiO3 to reduce the physical structure of the NaAlH4 during the ball milling process. © 2021 John Wiley & Sons Ltd","In solid-state hydrogen storage materials, especially NaAlH4, finding effective catalysts and using mechanical treatment represent promising solutions to overcome the drawbacks of NaAlH4. X-ray diffraction results indicated that SrTiO3 did not react or change during the milling and desorption (heating) processes.",_
!116,"As the world is shifting toward an increased reliance on renewable energy, the need for effective and robust energy carriers is more than pressing. In this context, hydrogen has a key role to play. However, the storage of hydrogen in a cost-effective, safe, and compact manner is a bottleneck to the future hydrogen economy primarily due to the lack of incentives and technical difficulties in storing hydrogen. So far, materials capable of ambient hydrogen uptake/release have a low storage capacity while high-capacity hydrides that may offer more compact alternatives still rely on very high hydrogen release temperatures. This chapter summarizes the current potential of the solid-state hydrogen technology in the renewable energy sector and potential paths to engineer the next generation of materials along with their hydrogen thermodynamic and kinetic paths. © 2021 Elsevier Inc.","As the world is shifting toward an increased reliance on renewable energy, the need for effective and robust energy carriers is more than pressing. So far, materials capable of ambient hydrogen uptake/release have a low storage capacity while high-capacity hydrides that may offer more compact alternatives still rely on very high hydrogen release temperatures.",_
!117,"Hydrogen stored in a solid state form of metal hydrides offers a safe and efficient storage technique for hydrogen application. In a closed metal hydride tank, stresses may occur on the tank wall due to hydride expansion during hydrogen absorption process. In the present investigation, a novel testing system for stress evolution of MlNi4.5Cr0.45Mn0.05 alloy in a closed cylindrical reactor during hydrogen absorption-desorption process was built. The results show that considerable swelling stress is developed on the inner reactor wall during activation process though a high free space of 45% is presented. Increasing hydrogen charging pressure and alloy loading fraction increase the as-generated swelling stress. The metal hydride particle expansion caused by hydrogen absorption is the intrinsic factor for swelling stress evolution. The presence of particle agglomerate in a closed tank in which its expansion is constrained is responsible for the observed swelling stress accumulation. © 2020 Hydrogen Energy Publications LLC",The results show that considerable swelling stress is developed on the inner reactor wall during activation process though a high free space of 45% is presented. Increasing hydrogen charging pressure and alloy loading fraction increase the as-generated swelling stress.,_
!118,"TiFe intermetallic compound has been extensively studied, owing to its low cost, good volumetric hydrogen density, and easy tailoring of hydrogenation thermodynamics by elemental substitution. All these positive aspects make this material promising for large-scale applications of solid-state hydrogen storage. On the other hand, activation and kinetic issues should be amended and the role of elemental substitution should be further understood. This work investigates the thermodynamic changes induced by the variation of Ti content along the homogeneity range of the TiFe phase (Ti:Fe ratio from 1:1–1:0.9) and of the substitution of Mn for Fe between 0 and 5 at%. In all considered alloys, the major phase is TiFe-type together with minor amounts of TiFe2 or β-Ti-type and Ti4Fe2O-type at the Ti-poor and rich side of the TiFe phase domain, respectively. Thermodynamic data agree with the available literature but offer here a comprehensive picture of hydrogenation properties over an extended Ti and Mn compositional range. Moreover, it is demonstrated that Ti-rich alloys display enhanced storage capacities, as long as a limited amount of β-Ti is formed. Both Mn and Ti substitutions increase the cell parameter by possibly substituting Fe, lowering the plateau pressures and decreasing the hysteresis of the isotherms. A full picture of the dependence of hydrogen storage properties as a function of the composition will be discussed, together with some observed correlations. © 2021 Elsevier B.V.","TiFe intermetallic compound has been extensively studied, owing to its low cost, good volumetric hydrogen density, and easy tailoring of hydrogenation thermodynamics by elemental substitution. Thermodynamic data agree with the available literature but offer here a comprehensive picture of hydrogenation properties over an extended Ti and Mn compositional range.",_
!119,"As a potential hydrogen storage material for solid hydrogen storage, the binary hydride MgH2 had the advantages of high hydrogen storage density and reversible hydrogen absorption and desorption. However, the applications of MgH2 were restricted due to the slow rate of hydrogen absorption and desorption, and the high working temperature. To date, in order to meet the requirements of solid hydrogen storage materials for vehicular hydrogen storage, many methods to improve the hydrogen storage performance of MgH2 were developed by scientific researchers such as alloying, nanocrystallization, and catalyst doping. These methods reduced the hydrogen desorption temperature of the system, increased the hydrogen absorption and desorption cycle stability. Among them, catalyst doping was the most extensively studied one, and it was considered to be a very effective way to improve the performance of magnesium-based hydrogen storage. A mechanical ball milling process was used to add the catalyst. During the ball milling process, the catalyst might react with the magnesium hydride in a solid state. Ball milling was a very important method of structural modification. It could not only conveniently control the composition of the alloy, but also could directly obtain materials with metastable structures such as nanocrystalline, amorphous and supersaturated solid solutions. In this method, metals (such as Fe, Co, Ni, Cu, etc.), metal compounds (such as Nb2O5, CeO2, TMTiO3 (TM=Ni, Co), etc.), transition metal halides (such as CeF4, CeF3, LaCl3, etc.), carbon-based materials (such as graphite, graphene, AC, CFs, etc.), metal-based and carbon-based composites were used as catalysts, and added single or in combination to magnesium-based alloys by mechanical ball milling. The research results showed that transition metals had a strong affinity for hydrogen atoms. During the dissociation of hydrogen molecules or the recombination of hydrogen atoms, the d electrons of transition metals and the electrons on the hydrogen atom/hydrogen molecular orbital were transferred and filled, which resulted in the interaction forces to promote the dissociation of hydrogen molecules and the recombination of hydrogen atoms. At the same time, after the metal catalyst was doped, many defects were generated on the surface of MgH2, which were conducive to charge and heat transfer. Furthermore, the metal oxides were cheap and easy to prepare. Doping transition metal oxides could effectively catalyze the hydrogen absorption and desorption reaction of MgH2. It could also be used as a lubricant and dispersant during the grinding process to prevent the agglomeration of MgH2 particles and refine the size of MgH2 particles, accelerate the hydrogen desorption kinetics of MgH2, catalyze the hydrogen absorption and desorption reaction of MgH2. Transition metal halides could react with MgH2 in the process of hydrogen absorption and desorption to generate transition metal hydrides. These transition metal hydrides could promote the dissociation of hydrogen molecules and the diffusion of hydrogen atoms, promote nucleation and reduction in the hydrogenation process. The reaction product of metal sulfide or metal hydride and MgH2 in the ball milling process had high catalytic activity, which could solve the problem of slow dehydrogenation/hydrogenation kinetics to a certain extent. In addition, MgS could provide abundant nucleation active sites, and Fe element could stabilize MgH2. LaF3 could react with Mg to form MgF2 and LaH3 phases during hydrogenation ball milling, which significantly increased the amount and rate of hydrogen desorption of magnesium. The catalytic mechanism was that LaH3 acted as a hydrogen pump. The addition of carbon-based materials could promote the nucleation of the Mg/MgH2 phase, refine the particle size, and improve the hydrogen absorption kinetics. Unfortunately, the effect was weaker than that of metal-based catalysts. Doped with metal-based and carbon-based composite catalysts, MgH2 could simultaneously obtain the effects of doped metal-based and carbon-based catalysts, such as the low dehydrogenation temperature, low dehydrogenation activation energy and excellent cycle stability. It could be seen that doped metal-based catalysts could generally promote the formation and decomposition of MgH2 bonds by generating a large number of defects or new phases, and then enhancing the dehydrogenation/hydrogenation kinetics of the hydrogen storage material system. Carbon-based materials doped with non-metals could effectively prevent MgH2 particles from agglomeration and grain growth during the ball milling process. In addition, its low density could maintain the high hydrogen storage capacity of MgH2 materials. In order to meet the practical standard, it was necessary to develop new technology and find new experimental methods. One of the important strategies to improve the hydrogen storage performance of MgH2 was synergistic utilization of metal-based materials and carbon-based materials as catalysts. To carry out composite catalysis research and to study the synergistic effect of different catalysts could help to improve the hydrogen storage performance of MgH2. With the help of simulation calculation or first principles, the mechanism of chemical reaction of MgH2 in the process of hydrogen absorption and desorption after catalyst doping could be further clarified. Therefore, the uniqueness and potential advantages of metal hydride hydrogen storage technology could be fully exploited. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.","Carbon-based materials doped with non-metals could effectively prevent MgH2 particles from agglomeration and grain growth during the ball milling process. Therefore, the uniqueness and potential advantages of metal hydride hydrogen storage technology could be fully exploited.",_
!120,"Density functional theory is adopted to study phase transitions, structural, elastic, and electronic properties of hydrogen storage K2PdH4. Firstly, the structural evolution of K2PdH4 is investigated under high pressure along with the hydrogen storage properties. In the ambient conditions, K2PdH4 crystallizes in a tetragonal structure with space group I4/mmm. As the pressure is increased gradually on the crystal, a phase transition is recorded to the orthorhombic structure with space group Immm. Subsequently, the density of states and electronic band structures are obtained for each phase. Mechanical properties such as ductility and brittleness are investigated using elastic constants which are crucial parameters for solid-state hydrogen storage materials. Moreover, several properties are analyzed using Young, shear and bulk modulus to reveal the bonding characteristics of K2PdH4 © S. Al and C. Kurkcu, 2021","Density functional theory is adopted to study phase transitions, structural, elastic, and electronic properties of hydrogen storage K2PdH4. Subsequently, the density of states and electronic band structures are obtained for each phase.",_
!121,"Mg2Si is a promising catalyst for Mg-based H2 storage materials due to its low cost, light weight, and non-toxic properties. This study investigates the effects of Na in hypo-eutectic Mg-1wt.%Si alloys for H2 storage applications. The addition of trace amounts of Na is vital in improving the H2 sorption kinetics, achieving a H2 storage capacity of 6.72 wt.% H at 350 °C under 2 MPa H2, compared to 0.31 wt.% H in the non-Na added alloy. The hydrogen sorption mechanisms were analysed with Johnson-Mehl-Avrami-Kolmogorov models. It was identified that Na affects the surface of the Mg alloys, forming porous Na2O and NaOH in addition to MgO, facilitating the diffusion of H2. Finally, in-situ synchrotron powder X-ray diffraction showed the Mg2Si catalyst is stable during the H2 sorption reactions. This result demonstrates the potential use of Mg–Mg2Si casting alloys for large scale hydrogen storage and transportation applications. © 2022 Elsevier B.V.","Mg2Si is a promising catalyst for Mg-based H2 storage materials due to its low cost, light weight, and non-toxic properties. This result demonstrates the potential use of Mg–Mg2Si casting alloys for large scale hydrogen storage and transportation applications.",_
!122,"High hydrogen density and low material costs make Mg as one of the most promising candidates for solid-state hydrogen storage. However, the practical applications of Mg are restricted by high reaction temperature and slow kinetics of hydrogen absorption/desorption. Here we present the improvements of both thermodynamics and kinetics of the hydride/deuteride of Mg (MgH2/MgD2) by utilizing the immiscible Mg–Cr system. Nanometer-sized MgD2 domains with the average crystallite size of ~10 nm embedded in a Cr matrix are formed in deuterated Mg0.25Cr0.75. X-ray diffraction and nuclear magnetic resonance spectroscopy studies show that the MgD2 domains are heavily distorted, which leads to the thermodynamic destabilization lowering the reaction temperature. Mg0.25Cr0.75 can reversibly absorb and desorb hydrogen/deuterium at a low temperature of 473 K. The enthalpy ΔH for deuterium desorption of Mg0.25Cr0.75−D is 72.1 kJ mol−1−D2, which is lower than ~74 kJ mol−1−D2 for bulk MgD2. The apparent activation energy for hydrogen desorption of Mg0.25Cr0.75−H is decreased to 75 kJ mol−1 from ~160 kJ mol−1 for bulk Mg, in which the dehydrogenation of nanometer-sized MgH2 is controlled by one-dimensional diffusion of hydrogen. Our work demonstrates that MgH2 nanostructured by an immiscible matrix is a useful strategy to alter the thermodynamic and kinetic properties. © 2021 Elsevier B.V.","Mg0.25Cr0.75 can reversibly absorb and desorb hydrogen/deuterium at a low temperature of 473 K. The enthalpy ΔH for deuterium desorption of Mg0.25Cr0.75−D is 72.1 kJ mol−1−D2, which is lower than ~74 kJ mol−1−D2 for bulk MgD2. Our work demonstrates that MgH2 nanostructured by an immiscible matrix is a useful strategy to alter the thermodynamic and kinetic properties.",_
!123,"Hydrogen storage using the metal hydrides and complex hydrides is the most convenient method because it is safe, enables high hydrogen capacity and requires optimum operating condition. Metal hydrides and complex hydrides offer high gravimetric capacity that allows storage of large amounts of hydrogen. However, the high operating temperature and low reversibility hindered the practical implementation of the metal hydrides and complex hydrides. An approach of combining two or more hydrides, which are called reactive hydride composites (RHCs), was introduced to improve the performance of the metal hydrides and complex hydrides. The RHC system approach has significantly enhanced the hydrogen storage performance of the metal hydrides and complex hydrides by modifying the thermodynamics of the composite system through the metathesis reaction that occurred between the hydrides, hence enhancing the kinetic and reversibility performance of the composite system. In this paper, the overview of the RHC system was presented in detail. The challenges and perspectives of the RHC system are also discussed. This is the first review report on the RHC system for solid-state hydrogen storage. © 2021 Hydrogen Energy Publications LLC","Hydrogen storage using the metal hydrides and complex hydrides is the most convenient method because it is safe, enables high hydrogen capacity and requires optimum operating condition. An approach of combining two or more hydrides, which are called reactive hydride composites (RHCs), was introduced to improve the performance of the metal hydrides and complex hydrides.",_
!124,"This paper details the process of designing, analysing, manufacturing, and testing an integrated solid-state hydrogen storage system. Analysis is performed to optimise flow distribution and pressure drop through the channels, and experimental investigations compare the effects of profile shape on the overall power output from the fuel cell. The storing of hydrogen is given much attention in the selection of a storage medium, and the effect of a cooling system to reduce the recharging time of the hydrogen storage vessel. The PTFE seal performed excellently, holding pressure over 60 bar, despite requiring changing each time the cell is opened. The assembly of the vessel was simple and straightforward, and there was no indication of pressure damage owing to the FEA analysis that was performed. The cooling chamber, although producing minor leaks due to design oversight, increased performance dramatically, showing a reduction in internal powder temperature from 130°C, down to 25°C during the absorption process, as well as reducing the absorption time down from 30 minutes to just over 5 minutes. The novel idea of implanting a sheathed thermocouple into the centre of the hydride powder proved to be highly valuable asset and provided important information, especially during desorption where the outside container could be heating up, while the inner powder is still cooling down, data that have not been seen before. © 2021 John Wiley & Sons Ltd.","This paper details the process of designing, analysing, manufacturing, and testing an integrated solid-state hydrogen storage system. The cooling chamber, although producing minor leaks due to design oversight, increased performance dramatically, showing a reduction in internal powder temperature from 130°C, down to 25°C during the absorption process, as well as reducing the absorption time down from 30 minutes to just over 5 minutes.",_
!125,"Slow hydrogenation kinetics and high de/absorption temperature of Mg/MgH2 still a challenge in solid state hydrogen storage systems for industrial and automobile applications. The effect of PdCl2 on the hydrogenation properties including kinetics of Mg/MgH2 has been investigated in the present study. The nanocomposites of Mg and PdCl2 were prepared using Ball Mill method with different concentrations of PdCl2. The synthesized nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), pressure-composition-isotherm (PCI) and differential scanning calorimetry (DSC). The result indicates that the maximum hydrogen storage capacity were achieved 6.15 wt% for Mg-5 wt% PdCl2 nanocomposites, while milled Mg only absorb 3.417 wt% H2 at 300 °C. The desorption kinetics not so much improved with PdCl2 concentration. It is concluded that the onset temperature of Mg-PdCl2 nanocomposites shifted towards lower side than milled Mg using DSC analysis. The SEM and XRD patterns confirm the phase identity maintain during ball milling. The new phases of PdH0.778, MgCl2, Mg6Pd and various phases of MgH2 in MgH2-PdCl2 nanocomposites were confirmed on the basis of XRD analysis and reported data of the sample. © 2022 Elsevier Ltd",The desorption kinetics not so much improved with PdCl2 concentration. It is concluded that the onset temperature of Mg-PdCl2 nanocomposites shifted towards lower side than milled Mg using DSC analysis.,_
!126,"The current energy transition imposes a rapid implementation of energy storage systems with high energy density and eminent regeneration and cycling efficiency. Metal hydrides are potential candidates for generalized energy storage, when coupled with fuel cell units and/or batteries. An overview of ongoing research is reported and discussed in this review work on the light of application as hydrogen and heat storage matrices, as well as thin films for hydrogen optical sensors. These include a selection of single-metal hydrides, Ti–V(Fe) based intermetallics, multi-principal element alloys (high-entropy alloys), and a series of novel synthetically accessible metal borohydrides. Metal hydride materials can be as well of important usefulness for MH-based electrodes with high capacity (e.g. MgH2 ~ 2000 mA h g−1) and solid-state electrolytes displaying high ionic conductivity suitable, respectively, for Li-ion and Li/Mg battery technologies. To boost further research and development directions some characterization techniques dedicated to the study of M-H interactions, their equilibrium reactions, and additional quantification of hydrogen concentration in thin film and bulk hydrides are briefly discussed. © 2020 Hydrogen Energy Publications LLC","Metal hydrides are potential candidates for generalized energy storage, when coupled with fuel cell units and/or batteries. Metal hydride materials can be as well of important usefulness for MH-based electrodes with high capacity (e.g. MgH2 ~ 2000 mA h g−1) and solid-state electrolytes displaying high ionic conductivity suitable, respectively, for Li-ion and Li/Mg battery technologies.",_
!127,"Hydrogen energy, with environment amicable, renewable, efficiency, and cost-effective advantages, is the future mainstream substitution of fossil-based fuel. However, the extremely low volumetric density gives rise to the main challenge in hydrogen storage, and therefore, exploring effective storage techniques is key hurdles that need to be crossed to accomplish the sustainable hydrogen economy. Hydrogen physically or chemically stored into nanomaterials in the solid-state is a desirable prospect for effective large-scale hydrogen storage, which has exhibited great potentials for applications in both reversible onboard storage and regenerable off-board storage applications. Its attractive points include safe, compact, light, reversibility, and efficiently produce sufficient pure hydrogen fuel under the mild condition. This review comprehensively gathers the state-of-art solid-state hydrogen storage technologies using nanostructured materials, involving nanoporous carbon materials, metal-organic frameworks, covalent organic frameworks, porous aromatic frameworks, nanoporous organic polymers, and nanoscale hydrides. It describes significant advances achieved so far, and main barriers need to be surmounted to approach practical applications, as well as offers a perspective for sustainable energy research. Copyright © 2021 Jie Zheng et al.","Hydrogen energy, with environment amicable, renewable, efficiency, and cost-effective advantages, is the future mainstream substitution of fossil-based fuel. Its attractive points include safe, compact, light, reversibility, and efficiently produce sufficient pure hydrogen fuel under the mild condition.",_
!128,"Rapid scale-up of the technologies for clean energy production, conversion and storage have been adopted by many countries in order to reduce demand for fossil fuels. Primary renewable energy such as solar, wind, and hydro are developed for energy production particularly for electricity generation. However, there are still some deficiencies in direct use of primary renewable energy sources; therefore, secondary energy sources (or carriers) have been recently established as clean energy sources. Hydrogen is a type of secondary energy sources with almost low density and light weight; therefore, it must be stored in the form of liquid or gas. The storage of hydrogen in the form of liquid requires very low temperature. Solid-state hydrogen storage on the surfaces of solids or within solids is a promising solution to above shortcomings for high-density energy storage. Herein, multi-layers solid-state materials with ability of hydrogen adsorption are presented, for the first time, including “mixed metal oxide (MMO) nanostructures” and “silicate layers”. The MMO is CuCe2(MoO4)4 nanostructures which synthesized via Pechini method in front of various chelating agents such as trimesic acid, maleic acid, succinic acid, and malonic acid, while the silicate layer is nanoclay montmorillonite K10. In this study, the experimental observations reveal a pure formation of CuCe2(MoO4)4 nanostructures in malonic acid at 500 °C, with almost regular nanosized morphology of 20–25 nm. The selected sample is then used for nanocomposite formation by dispersing the CuCe2(MoO4)4 nanostructures into the montmorillonite K10 solution. The final nanocomposites exhibit a superior electrochemical hydrogen storage performance, in terms of “maximum discharge capacity of ∼ 3750 mAh/g)” and “efficiency of about 70%” in an alkaline medium. It must be mentioned that though the maximum discharge capacity of the CuCe2(MoO4)4 nanostructures is higher than nanocomposites (for example ∼ 6000 mAh/g), but the efficiency (discharge/charge) is lower (∼48%). It can be emphasized that this nanocomposite can be applied as promising host in an electrochemical hydrogen storage system, which can meet the U.S. Department of Energy (DOE) hydrogen storage targets. © 2021 Elsevier Ltd","Hydrogen is a type of secondary energy sources with almost low density and light weight; therefore, it must be stored in the form of liquid or gas. Herein, multi-layers solid-state materials with ability of hydrogen adsorption are presented, for the first time, including “mixed metal oxide (MMO) nanostructures” and “silicate layers”.",_
!129,"LiAlH4 is regarded as a potential material for solid-state hydrogen storage because of its high hydrogen content (10.5 wt%). However, its high decomposition temperature, slow dehydrogenation kinetics and irreversibility under moderate condition hamper its wider applications. Mechanical milling treatment and doping with a catalyst or additive has drawn significant ways to improve hydrogen storage properties of LiAlH4. Microstructure or nanostructure materials were developed by using a ball milling technique and doping with various types of catalysts or additives which had dramatically improved the efficiency of LiAlH4. However, the state-of-the-art technologies is still far from meeting the expected goal for the applications. In this paper, the overview of the recent advances in catalyst-enhanced LiAlH4 for solid-state hydrogen storage is detailed. The remaining challenges and the future prospect of LiAlH4–catalyst system is also discussed. This paper is the first systematic review that focuses on catalyst-enhanced LiAlH4 for solid-state hydrogen storage. © 2021 Hydrogen Energy Publications LLC",Mechanical milling treatment and doping with a catalyst or additive has drawn significant ways to improve hydrogen storage properties of LiAlH4. This paper is the first systematic review that focuses on catalyst-enhanced LiAlH4 for solid-state hydrogen storage.,_
!130,"Magnesium hydrides (MgH2) have attracted extensive attention as solid-state H2 storage, owing to their low cost, abundance, excellent reversibility, and high H2 storage capacity. This review comprehensively explores the synthesis and performance of Mg-based alloys. Several factors affecting their hydrogen storage performance were also reviewed. The metals addition led to destabilization of Mg–H bonds to boost the dehydrogenation process. A unique morphology could provide more available active sites for the dissociation/recombination of H2 and allow the activation energy reduction. Also, an appropriate support prevent the agglomeration of Mg particles, hence, sustains their nanosize particles. Moreover, the perspective of avenues for future research presented in this review is expected to act as a guide for the development of novel Mg-based H2 storage systems. New morphological shape of catalysts, more unexplored and highly potential waste materials, and numerous synthesis procedures should be explored to further enhance the H2 storage of Mg-based alloys. © 2021 Hydrogen Energy Publications LLC","Moreover, the perspective of avenues for future research presented in this review is expected to act as a guide for the development of novel Mg-based H2 storage systems. New morphological shape of catalysts, more unexplored and highly potential waste materials, and numerous synthesis procedures should be explored to further enhance the H2 storage of Mg-based alloys.",_
!131,"Energy is an essential requirement in our daily lives. Currently, most of our energy demands are fulfilled by fossil fuels. After 20 years, non-renewable fossil fuels are estimated to plummet rapidly. The world will face energy shortage and will seek for a new environmental method of energy generation for transportation, economy and application. Hydrogen is a fascinating energy carrier that is considered as ‘hydrogen economy’ for the future. The key challenge in developing the hydrogen economy is the context of hydrogen storage. Storing hydrogen via the solid-state method has received special attention and consideration because of its safety and larger storage capacity. A light complex hydride, NaAlH4, is considered as an attractive material for solid-state hydrogen storage owing to its high hydrogen capacity, bulk in availability and low cost. Sluggish sorption kinetics and poor reversibility have driven research into various catalysts to enhance its hydrogen storage properties. This review article examines the development of different catalysts and their effects on the hydrogen storage properties of NaAlH4. The addition of catalyst offers synergistic catalytic effect on the dehydrogenation performance of NaAlH4. Doping NaAlH4 with catalyst promote promising results such as lower decomposition temperature, improved kinetics and reduced activation energy. Superior performance on the dehydrogenation performance of NaAlH4 doping with the catalyst may be due to the nanosized catalyst particle and in situ formed active species that may serve as nucleation sites at the surface of the NaAlH4 matrix and benefiting the kinetics properties of NaAlH4. © 2020 Hydrogen Energy Publications LLC","Sluggish sorption kinetics and poor reversibility have driven research into various catalysts to enhance its hydrogen storage properties. Doping NaAlH4 with catalyst promote promising results such as lower decomposition temperature, improved kinetics and reduced activation energy.",_
!132,"First principles calculations have been adopted to explore ground-state and high-pressure properties of KCaH3 and KSrH3 orthorhombic perovskite hydrides for the purpose of solid-state hydrogen storage. Formation enthalpies of materials, structural and mechanical properties, electronic and hydrogen storage properties are computed and examined. The computed formation enthalpies and phonon frequencies of KCaH3 and KSrH3 indicate dynamical stability at 0 GPa. The gravimetric hydrogen densities of KCaH3 and KSrH3 are found to be 3.55 wt% and 2.28 wt%, respectively. Also, the hydrogen desorption temperatures are calculated as 449 K and 394 K for KCaH3 and KSrH3. Elastic constants for each phase and several parameters derived from elastic constants are computed and evaluated, such as bulk and Shear modulus. The B/G ratios of materials depict that both KCaH3 and KSrH3 are brittle materials. The electronic properties show band gaps for both materials at 0 GPa, confirming an insulating nature and as pressure increases the band gap shrinks for KCaH3 and disappears for KSrH3. Graphical abstract: [Figure not available: see fulltext.]. © 2022, The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature.","First principles calculations have been adopted to explore ground-state and high-pressure properties of KCaH3 and KSrH3 orthorhombic perovskite hydrides for the purpose of solid-state hydrogen storage. © 2022, The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature.",_
!133,"MgH2 is considered one of the most promising candidates for solid-state hydrogen storage. However, the dehydrogenation of MgH2 generally happens at temperatures above 250 °C even after catalyzing and/or nano-confining modifications, thus embarrassing the practical use of MgH2 in fuel cells. NH4Cl is a cheap chemical which has mature synthesis technologies in large industrial productions. The protonic H (Hδ+) in NH4Cl and the hydridic H (Hδ−) in MgH2 have coulomb interaction which allow MgH2 to release hydrogen at milder temperatures. In this article, by designing the molar ratio of MgH2 and NH4Cl as 2:1 (equal molar ratio of Hδ+ and Hδ−), the hydrogen release peak temperature can be decreased to 164.8 °C, and the ammonia generation is remarkably suppressed. In particular, graphene introduction to the 2MgH2+NH4Cl composite can further reduce the hydrogen release temperature to 161.2 °C and improve the hydrogen purity up to 97.26%. It is revealed that the smaller particle size and the better dispersion of 2MgH2+NH4Cl/graphene composite allows better interaction between Hδ+ and Hδ−, which brings down the hydrogen desorption temperature and improves the hydrogen purity. © 2021 Elsevier B.V.",MgH2 is considered one of the most promising candidates for solid-state hydrogen storage. NH4Cl is a cheap chemical which has mature synthesis technologies in large industrial productions.,_
!134,"The on-board hydrogen storage needs light, compact, and affordable system to replace the compressed hydrogen tanks. MgH2 is regarded as one of the most promising candidates for solid-state hydrogen storage. Due to the thermodynamically stable Mg-H bond, the poor dissociation ability of H2 molecules and recombination ability of H atoms on Mg surface, and the low diffusion coefficient of H atoms in Mg, especially in MgH2, there remains a challenge to design a material capable of absorbing and desorbing hydrogen rapidly at moderate temperatures. Herein, common strategies to improve the hydrogen storage properties of Mg-based materials are introduced. Some recent studies for overcoming the thermodynamic and kinetic barriers are reviewed, especially the approaches to fabricate nanostructure in Mg-based materials. The nanometric crystals or particles are synthesized by mechanical deformation, reduction in solution, physical/chemical vapor deposition, interface confinement. The nano-catalyst can be decorated by external doping or in-situ synthesis. In particular, the thermodynamic/kinetic parameters for hydrogenation and dehydrogenation are provided, and the mechanisms for the enhanced properties are summarized. The principles of structural design and catalytic decoration are discussed, and challenges and perspectives of fabricating nanostructures in Mg-based hydrogen storage materials are proposed. © 2021 Elsevier B.V.","Herein, common strategies to improve the hydrogen storage properties of Mg-based materials are introduced. The nanometric crystals or particles are synthesized by mechanical deformation, reduction in solution, physical/chemical vapor deposition, interface confinement.",_
!135,"Aluminum hydride (AlH3) is a binary metal hydride that contains more than 10.1 wt% of hydrogen and possesses a high volumetric hydrogen density of 148 kg H2 m−3. Pristine AlH3 can readily release hydrogen at a moderate temperature below 200 °C. Such high hydrogen density and low desorption temperature make AlH3 one of most promising hydrogen storage media for mobile application. This review covers the research activity on the structures, synthesis, decomposition thermodynamics and kinetics, regeneration and application validation of AlH3 over the past decades. Finally, the future research directions of AlH3 as a hydrogen storage material will be revealed. © 2020","Pristine AlH3 can readily release hydrogen at a moderate temperature below 200 °C. Finally, the future research directions of AlH3 as a hydrogen storage material will be revealed.",_
!136,"In current research, solid-state materials are often used as the most promising materials for hydrogen storage materials in comparison of the other storage materials. Hydrogen is considered as an important source of energy storage system for automotive applications. Hydrogen as a conventional fuel offers high potential benefits due to their easily storage and transportation and considered as an alternative fuel because of its natural abundance and a clean and sustainable energy carrier. It is available in abundance and is the renewable sources of energy and, more significantly, is a clean fuel. Metal hydrides are able to store relatively large amounts of hydrogen in a solid phase as compared with other solid-state materials with safety and long-term stability. This perspective chapter highlights the brief idea about the various solid-state materials as storage of hydrogen and various applications in energy fields. © 2021 Elsevier Inc. All rights reserved.",Hydrogen is considered as an important source of energy storage system for automotive applications. Metal hydrides are able to store relatively large amounts of hydrogen in a solid phase as compared with other solid-state materials with safety and long-term stability.,_
!137,"Safe, compact, lightweight and cost-effective hydrogen storage is one of the main challenges that need to be addressed to effectively deploy the hydrogen economy. LiAlH4, as a solid-state hydrogen storage material, presents several advantages such as high hydrogen storage capacity, low price and abundant sources. Unfortunately, neither thermodynamic nor kinetic properties of dehydrogenation for LiAlH4 can fulfill the requirements of practical application. Thus, a series of spinel ferrite nanoparticles such as XFe2O4 (X = Ni, Co, Mn, Cu, Zn, Fe) were prepared by using the modified thermal decomposition method, and then doped into LiAlH4 by using ball milling. Our results show that LiAlH4 doped with 7 wt% NiFe2O4 starts to release hydrogen at 69.1 °C, and the total amount of hydrogen released is 7.29 wt% before 300 °C. The activation energies of the two-step hydrogen release reactions of LiAlH4 doped with 7 wt% NiFe2O4 are 42.32 kJ mol−1 and 71.42 kJ mol−1, which are 59.0% and 63.6% lower than those of as-received LiAlH4, respectively. Combining the density functional theory (DFT) calculations, we reveal that both the presence of NiFe2O4 and in-situ formed Al4Ni3 in ball-milling decrease the desorption energy barrier of Al-H bonding in LiAlH4 and accelerate the breakdown of Al-H bonding through the interfacial charge transfer and the dehybridization of the Al-H cluster. Thus, the experimental and theoretical results open a new avenue toward designing high effective catalysts applied to LiAlH4 as a candidate for hydrogen storage. © 2021","Safe, compact, lightweight and cost-effective hydrogen storage is one of the main challenges that need to be addressed to effectively deploy the hydrogen economy. Thus, a series of spinel ferrite nanoparticles such as XFe2O4 (X = Ni, Co, Mn, Cu, Zn, Fe) were prepared by using the modified thermal decomposition method, and then doped into LiAlH4 by using ball milling.",_
!138,"Despite the fact that the affinities of both palladium and magnesium with hydrogen have been studied for many years, information about magnesium-palladium alloys is still incomplete. Although palladium is an extremely expensive metal and magnesium palladium alloys will likely never applied as solid-state hydrogen storage materials, the interaction of these alloys with hydrogen may be useful for broadening knowledge or finding applications as hydrogen splitters, catalysts, and hydrogen sensors. In this work, two types of calorimetric techniques were applied to measure the thermodynamic properties of magnesium-rich alloys from the Mg-Pd system (containing 97.7; 85.4; 80.6; 79.9; 72.3; 70.7; 64.5 at% of Mg respectively). The solution calorimetric method was used to determine the heat of solution of liquid magnesium and palladium in liquid tin. Additionally, the standard enthalpies of formation of six alloys corresponding to the intermetallic phases of the Mg-rich region were measured. These alloys were prepared from pure Mg and Pd, which were melted in a glove box filled with high purity argon, with a very low concentration of impurities. All the obtained alloys were structurally analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDS) methods. Moreover, DSC studies were used to determine the transformation temperatures in the Mg-rich region. The values of the standard formation enthalpy of the studied alloys were determined to be −27.3 ± 0.8 kJ/mol at., −33.4 ± 0.9 kJ/mol at., −35.2 ± 1.4 kJ/mol at., −44.2 ± 0.9 kJ/mol at., −46.0 ± 0.7 kJ/mol at., and −54.3 ± 2.3 kJ/mol at. These values were compared with the data calculated using the Miedema model, as well as with existing literature data for the Mg6Pd and Mg5Pd2 phases. © 2020 Elsevier B.V.","These alloys were prepared from pure Mg and Pd, which were melted in a glove box filled with high purity argon, with a very low concentration of impurities. All the obtained alloys were structurally analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDS) methods.",_
!139,"Hydrogen has the highest gravimetric density (energy density per unit mass) of any fuel. The combustion of hydrogen releases energy in the form of heat. When hydrogen reacts with oxygen in a fuel cell, the reaction releases energy in the form of electricity. Unlike hydrocarbon-based fuels, the generation of energy from either the combustion of hydrogen or the reaction of hydrogen with oxygen in a fuel cell is not accompanied by the emission of greenhouse gases. This makes hydrogen a promising solution to solve global warming issues. However, hydrogen has a low volumetric density (low energy density per unit volume) which makes storing or transporting hydrogen extremely difficult and expensive. To accelerate the utilization of hydrogen as an energy carrier, it is necessary to develop advanced hydrogen storage methods that have the potential to have a higher energy density. The hydrogen storage market is segmented by application into: (1) Stationary power: stored hydrogen is consumed for example in a fuel cell for use in backup power stations, refueling stations, power stations; (2) Portable power: hydrogen storage applications for electronic devices such as mobile phones, flash lights, and portable generators; and (3) Transportation: industries including automobiles, aerospace, unmanned aerial systems, and hydrogen tanks used throughout the hydrogen supply chain. The increasing development of light and heavy fuel cell vehicles is expected to drive the development of on-board solid-state hydrogen technologies. A large number of research groups worldwide for many years have been trying to develop materials having the right set of thermodynamic and kinetic properties, along with all of the physical properties (high gravimetric density, high volumetric density, etc.) to allow for low-pressure storage system in ambient conditions. However, to date, no material has been found that satisfies all the desired properties to be viably used in many applications. Even if we consider only three parameters namely gravimetric density, volumetric density, and system cost, no materials that can meet the ultimate targets of the U.S. Department of Energy (DOE) or the 2030 targets of the European Union's Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and the New Energy and Industrial Technology Development Organization (NEDO) in Japan. The present article reviews advances in solid-state hydrogen storage technology and compares the opportunities and challenges of selected materials. The materials reviewed in this article have a wider spectrum than the materials reviewed in other existing articles, including carbon nanotubes (CNTs), metal–organic frameworks (MOFs), graphene, boron nitride (BN), fullerene, silicon, amorphous manganese hydride molecular sieve, and metal hydrides. Pioneering works, important breakthroughs, as well as the latest developments for promising materials are also reviewed. In addition, for the first time the targets set by several official regulatory agencies for solid-state hydrogen storage are summarized. Achievements in academic and industrial research are compared against these targets. The future prospects of promising materials are analyzed based on how its practical application can be implemented according to market needs. © 2022 Hydrogen Energy Publications LLC","The materials reviewed in this article have a wider spectrum than the materials reviewed in other existing articles, including carbon nanotubes (CNTs), metal–organic frameworks (MOFs), graphene, boron nitride (BN), fullerene, silicon, amorphous manganese hydride molecular sieve, and metal hydrides. The future prospects of promising materials are analyzed based on how its practical application can be implemented according to market needs.",_
!140,"TiFe-based alloys are solid-state hydrogen storage materials operated at room temperature (RT). The current study presents a systematic approach for solving the activation issue (difficulty in the first hydrogenation), one of the major obstacles to the practical application of TiFe alloys, via the use of a secondary AB2 phase. Based on the Ti–Fe–Cr ternary phase diagram, Ti–Fe–Cr alloys containing 80 at% Ti(Fe,Cr) (AB phase) and 20 at% Ti(Fe,Cr)2 (AB2 phase) were designed; the Cr concentrations in the AB and AB2 phase were systematically varied while maintaining fixed phase fractions. Activation at RT was achieved when the overall Cr concentration was higher than 9.7 at%. Analysis of the activation characteristics of the individual phases revealed that the AB2 phase readily absorbed hydrogen, thereby initiating activation of AB + AB2 alloys. Notably, higher Cr concentrations enable the AB phase to absorb hydrogen at RT during the activation process, although the kinetics are much slower than that of the co-existing AB2 phase. The equilibrium hydrogen pressures from the pressure-composition isotherms decrease as the Cr concentration increases, indicating that Cr stabilizes hydrides. Increased hydride stability may also promote the kinetics of the initial hydride formation in both the AB and AB2 phases. An optimal composition for Ti–Fe–Cr alloys can be designed given the conditions of easy activation at RT and maximum reversible capacity within an operating pressure range. © 2021 Elsevier B.V.",TiFe-based alloys are solid-state hydrogen storage materials operated at room temperature (RT). An optimal composition for Ti–Fe–Cr alloys can be designed given the conditions of easy activation at RT and maximum reversible capacity within an operating pressure range.,_
!141,"This paper aims at addressing the exploitation of solid-state carriers for hydrogen storage, with attention paid both to the technical aspects, through a wide review of the available integrated systems, and to the social aspects, through a preliminary overview of the connected impacts from a gender perspective. As for the technical perspective, carriers to be used for solid-state hydrogen storage for various applications can be classified into two classes: metal and complex hydrides. Related crystal structures and corresponding hydrogen sorption properties are reviewed and discussed. Fundamentals of thermodynamics of hydrogen sorption evidence the key role of the enthalpy of reaction, which determines the operating conditions (i.e., temperatures and pressures). In addition, it rules the heat to be removed from the tank during hydrogen absorption and to be delivered to the tank during hydrogen desorption. Suitable values for the enthalpy of hydrogen sorption reaction for operating conditions close to ambient (i.e., room temperature and 1–10 bar of hydrogen) are close to 30 kJ·molH2−1 . The kinetics of the hydrogen sorption reaction is strongly related to the microstructure and to the morphology (i.e., loose powder or pellets) of the carriers. Usually, the kinetics of the hydrogen sorption reaction is rather fast, and the thermal management of the tank is the rate-determining step of the processes. As for the social perspective, the paper arguments that, as it occurs with the exploitation of other renewable innovative technologies, a wide consideration of the social factors connected to these processes is needed to reach a twofold objective: To assess the extent to which a specific innovation might produce positive or negative impacts in the recipient socioeconomic system and, from a sociotechnical perspective, to explore the potential role of the social components and dynamics in fostering the diffusion of the innovation itself. Within the social domain, attention has been paid to address the underexplored relationship between the gender perspective and the enhancement of hydrogen-related energy storage systems. This relationship is taken into account both in terms of the role of women in triggering the exploitation of hydrogen-based storage playing as experimenter and promoter, and in terms of the intertwined impact of this innovation in their current conditions, at work, and in daily life. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.","Suitable values for the enthalpy of hydrogen sorption reaction for operating conditions close to ambient (i.e., room temperature and 1–10 bar of hydrogen) are close to 30 kJ·molH2−1 . This relationship is taken into account both in terms of the role of women in triggering the exploitation of hydrogen-based storage playing as experimenter and promoter, and in terms of the intertwined impact of this innovation in their current conditions, at work, and in daily life.",_
!142,"A systematic investigation was performed on the 4MgH2 + LiAlH4 destabilized system with the inclusion of 5 wt% Al2TiO5 that was prepared by a ball milling process, and the hydrogen sorption performances were studied for the first time. A great advancement of the onset dehydrogenation temperature and de/rehydrogenation kinetics of 4MgH2 + LiAlH4 composite was achieved by doping Al2TiO5 to the composite. For the first and second desorption stages, the 4MgH2 + LiAlH4 + 5 wt% Al2TiO5 composite began to liberate hydrogen at 85 °C and 230 °C. In comparison, the undoped system commenced to liberate hydrogen at 120 °C and 270 °C, which were 35 °C and 10 °C lower, respectively when contrasted with the undoped composite. For the rehydrogenation kinetics, about 1.9 wt% hydrogen was absorbed within 5 min for the 5 wt% Al2TiO5-doped 4MgH2 + LiAlH4 system, whereas the neat sample only absorbed about 1.2 wt% hydrogen under similar conditions. As for the dehydrogenation kinetics, 4MgH2 + LiAlH4 + 5 wt% Al2TiO5 composite desorbed 1.7 wt% hydrogen within 10 min of desorption, while the 4MgH2 + LiAlH4 system released 0.8 wt% hydrogen in the same time frame. The apparent activation energy for the MgH2-relevant decomposition decreased from 121 kJ/mol (4MgH2 + LiAlH4 system) to 102 kJ/mol, after 5 wt% Al2TiO5 was introduced into the destabilized system. The decline in particle size also enhance the hydrogen storage behaviors. The synergistic effect of Al2TiO5 on the hydrogen storage behavior of 4MgH2 + LiAlH4 sample is attributed to the formation of new species of TiH2, AlTi2 and LiTi2O4 after ball milling and heating process, which acted as a real catalyser in the 4MgH2 + LiAlH4 + 5 wt% Al2TiO5 destabilized system. © 2021 Elsevier B.V.","A great advancement of the onset dehydrogenation temperature and de/rehydrogenation kinetics of 4MgH2 + LiAlH4 composite was achieved by doping Al2TiO5 to the composite. In comparison, the undoped system commenced to liberate hydrogen at 120 °C and 270 °C, which were 35 °C and 10 °C lower, respectively when contrasted with the undoped composite.",_
!143,"Hydrogen energy is a key role in novel renewable energy production/consumption technologies. Traditional hydrogen energy systems are suffered from low density, high production cost, low efficiency, and storage complications. With the advent of solid-state hydrogen storage technology, many of above shortcomings are fulfilled, however, there are several unknown points, particularly in mixed metal oxides, which need more attention. Herein, we report the production of an engineered truncated octahedron shaped nanocrystal containing cobalt (Co), cerium (Ce), and Molybdenum (Mo) ions, emphasizing the general formula CoCe2(MoO4)4 via a solution combustion method. Experimental observations reveal that the CoCe2(MoO4)4 nanocrystals are purely formed in maltose at 700 °C, with almost regular truncated octahedron morphology, having an octahedral edge-size of around 45 nm. This morphological arrangement exhibits significantly an enhanced electrochemical hydrogen storage performance, in an alkaline medium, with maximum discharge capacity of ~4750 mAh/g. © 2020 Elsevier B.V.","Herein, we report the production of an engineered truncated octahedron shaped nanocrystal containing cobalt (Co), cerium (Ce), and Molybdenum (Mo) ions, emphasizing the general formula CoCe2(MoO4)4 via a solution combustion method. Experimental observations reveal that the CoCe2(MoO4)4 nanocrystals are purely formed in maltose at 700 °C, with almost regular truncated octahedron morphology, having an octahedral edge-size of around 45 nm.",_
!144,"Recently, hydrogen (H2 ) has emerged as a superior energy carrier that has the potential to replace fossil fuel. However, storing H2 under safe and operable conditions is still a challenging process due to the current commercial method, i.e., H2 storage in a pressurised and liquified state, which requires extremely high pressure and extremely low temperature. To solve this problem, research on solid-state H2 storage materials is being actively conducted. Among the solid-state H2 storage materials, borohydride is a potential candidate for H2 storage owing to its high gravimetric capacity (majority borohydride materials release >10 wt% of H2 ). Mg(BH4 )2, which is included in the borohydride family, shows promise as a good H2 storage material owing to its high gravimetric capacity (14.9 wt%). However, its practical application is hindered by high thermal decomposition temperature (above 300◦ C), slow sorption kinetics and poor reversibility. Currently, the general research on the use of additives to enhance the H2 storage performance of Mg(BH4 )2 is still under investigation. This article reviews the latest research on additive-enhanced Mg(BH4 )2 and its impact on the H2 storage performance. The future prospect and challenges in the development of additive-enhanced Mg(BH4 )2 are also discussed in this review paper. To the best of our knowledge, this is the first systematic review paper that focuses on the additive-enhanced Mg(BH4 )2 for solid-state H2 storage. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.","Mg(BH4 )2, which is included in the borohydride family, shows promise as a good H2 storage material owing to its high gravimetric capacity (14.9 wt%). However, its practical application is hindered by high thermal decomposition temperature (above 300◦ C), slow sorption kinetics and poor reversibility.",_
!145,"Chemically hydrogenated graphene possesses a theoretical hydrogen storage capacity of 7.7 wt%, and will release H2 gas upon thermal decomposition, making it an intriguing material for hydrogen storage applications. Recent works have demonstrated that this material can be synthesized at multi-gram scale quantities, and it has already been safely demonstrated as a hydrogen source to power a PEM fuel cell. While these results are promising, further characterization and evaluation of this material as it pertains to hydrogen storage must be carried out. In this work, we characterize various properties of chemically hydrogenated graphene, which will be key in the application of this material as a hydrogen storage medium moving forward. These include: theoretical calculation of the material's total volumetric energy density, the dependence of both temperature and surrounding atmosphere on the release of hydrogen gas, thermal expansion of the material upon heating, and the activation energy associated with hydrogen release. © 2021","Recent works have demonstrated that this material can be synthesized at multi-gram scale quantities, and it has already been safely demonstrated as a hydrogen source to power a PEM fuel cell. While these results are promising, further characterization and evaluation of this material as it pertains to hydrogen storage must be carried out.",_
!146,"While MgH2 has been widely regarded as a promising solid-state hydrogen storage material, the high operating temperature and sluggish kinetics pose a major bottleneck for its practical application. Herein, V4Nb18O55 microspheres composed of nanoparticles with size of tens of nanometers are fabricated to promote H2 desorption and absorption properties of MgH2, which results in the uniform formation of Nb/V interfaces based on a molecular scale during the reversible hydrogen storage process. It is experimentally and theoretically demonstrated that the uniform building of Nb/V interfaces not only preserves the ability of Nb in weakening Mg-H bonds but also alleviates the strong adsorption capacity of metallic Nb toward hydrogen atoms, leading to a relative energy barrier for the whole dehydrogenation process of MgH2 of only 0.5 eV, which is 0.22 and 0.43 eV lower than that of Nb and V, respectively. As a result, under the addition of V4Nb18O55 microspheres, the onset H2 desorption temperature of MgH2 is decreased to 165 °C, 125 °C lower than that of bulk MgH2, and the complete hydrogenation of Mg could be realized even at room temperature, while almost no H2 adsorption is observed for bulk Mg at a high temperature of 50 °C. © 2022 The Authors. Small Structures published by Wiley-VCH GmbH.","While MgH2 has been widely regarded as a promising solid-state hydrogen storage material, the high operating temperature and sluggish kinetics pose a major bottleneck for its practical application. It is experimentally and theoretically demonstrated that the uniform building of Nb/V interfaces not only preserves the ability of Nb in weakening Mg-H bonds but also alleviates the strong adsorption capacity of metallic Nb toward hydrogen atoms, leading to a relative energy barrier for the whole dehydrogenation process of MgH2 of only 0.5 eV, which is 0.22 and 0.43 eV lower than that of Nb and V, respectively.",_
!147,"With the rapid increase of global warming and CO2 emissions from conventional fuels, the world is seeking an international commitment from all-dominating countries for an emission cut down of about 55–60% till 2050. Molecular hydrogen is the most-favored chemical fuel alternative for both stationary and mobile applications. Hydrogen is the most efficient energy carrier known to us with the highest heating value per mass, i.e., 120–142 MJ/kg of all chemical fuels. Hydrogen also has the highest gross calorific value being 141.7 MJ/kg significantly higher than petrol 46.4 MJ/kg and diesel 45.6 MJ/kg for 0 °C at 1 bar. The production of hydrogen gas is a challenge itself. Water being the only by-product of the energy generation and zero emissions, hydrogen is regenerative and eco friendly. Gravimetric density and volumetric density are crucial for stationary and mobile applications. In this paper, the storage methods reviewed were high-pressure cylinder (upto 800 bars) using different metals and lightweight composite materials, storage of hydrogen in a liquid state using cryogenic tanks at 21 K, storage of hydrogen using the metal–organic framework and solid materials, chemical storage using covalent and ionic compounds, storage using selective few metals which possess property to absorb hydrogen excessively in large amount, storage that uses nanostructured based metal hydrides and absorption of hydrogen using carbon-based materials like Graphene. Hydrogen can also be stored indirectly in reactive metals using metal hydrides and chemisorptive techniques in Li, Na, Al, or Zn and other alkali elements. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.",Molecular hydrogen is the most-favored chemical fuel alternative for both stationary and mobile applications. Hydrogen also has the highest gross calorific value being 141.7 MJ/kg significantly higher than petrol 46.4 MJ/kg and diesel 45.6 MJ/kg for 0 °C at 1 bar.,_
!148,"Metals and alloys forming reversible hydrides with hydrogen gas are potential building blocks for compact, solid state hydrogen storage systems. Based on the materials’ thermodynamic characteristics, their use as temperature-swing gas compression and delivery systems in the hydrogen economy is also possible. Given the wide variety of materials developed and tested at laboratory and pilot scales, a harmonized method of selecting the feasible material(s) for a particular real-life application is required. This study proposes a system selection framework based on a normalized, multi-criteria metric. Using calculated values of multi-criteria metric, multi-criteria screening and ranking of potential materials has been demonstrated for a particular use case. It is found that the alloy TiMn1.52 having value of additive metric between 0.25 and 0.35 represents the best material for a single stage system. The alloy pair CaNi5–Ti1.5CrMn represents the best alternative for a two-stage system with additive metric values between 0.63 and 0.82. Energy and economic characteristics of the metal hydride gas compression and delivery systems are evaluated and compared with an equivalent mechanical compression system producing the same final effect (i.e., delivery of a given quantity of gas at a defined pressure). © 2021 Hydrogen Energy Publications LLC","Given the wide variety of materials developed and tested at laboratory and pilot scales, a harmonized method of selecting the feasible material(s) for a particular real-life application is required. Energy and economic characteristics of the metal hydride gas compression and delivery systems are evaluated and compared with an equivalent mechanical compression system producing the same final effect (i.e., delivery of a given quantity of gas at a defined pressure).",_
!149,"Metallic amidoboranes are widely investigated candidates for solid-state hydrogen storage, and much focus shifted recently toward bimetallic amidoboranes. Bimetallic amidoboranes are expected to introduce novel and enhanced physicochemical properties regarding storage and stability. However, these materials are still scarce and mostly grouped around magnesium- or aluminum-containing compounds. We present here a rapid and green mechanochemical solvent-free synthesis of two novel calcium-containing bimetallic amidoboranes, Li2Ca(NH2BH3)4 and Na2Ca(NH2BH3)4, from metal hydrides and ammonia borane. The insight into mechanochemical syntheses is provided by the in situ tandem synchrotron X-ray diffraction and thermal monitoring. The in situ data reveal how the choice of alkali metal hydride governs the course of reactions and their thermal profiles. In situ monitoring of thermal dehydrogenation of these materials is conducted by mass spectrometry and infrared spectroscopy, showing how the course of thermal decomposition varies depending on the structure of the amidoborane, resulting however in the same final products. These new hydrogen-rich bimetallic amidoboranes are structurally characterized by high-resolution powder X-ray diffraction, and they both show potential for hydrogen storage applications: high theoretical gravimetric capacities and low desorption temperatures of hydrogen without the significant presence of harmful gases. We also show how the choice of the milling reactor material can be decisive for the efficiency and overall success of the mechanochemical synthetic procedure, which may impact the design of milling syntheses for other thermally labile chemical systems.  © 2021 American Chemical Society.","However, these materials are still scarce and mostly grouped around magnesium- or aluminum-containing compounds. These new hydrogen-rich bimetallic amidoboranes are structurally characterized by high-resolution powder X-ray diffraction, and they both show potential for hydrogen storage applications: high theoretical gravimetric capacities and low desorption temperatures of hydrogen without the significant presence of harmful gases.",_
!150,"Magnesium hydride (MgH2) is the best candidate material to store hydrogen in the solid-state form owing to its advantages such as good reversibility, high hydrogen storage capacity (7.6 wt%), low raw material cost and abundance in the earth. Nevertheless, slow desorption/absorption kinetics and high thermodynamic stability are two issues that have constrained the commercialization of MgH2 as a solid-state hydrogen storage material. So, to boost the desorption/absorption kinetics and to alter the thermodynamics of MgH2, hafnium tetrachloride (HfCl4) was used as a catalyst in this study. Different percentages of HfCl4 (5, 10, 15 and 20 wt%) were added to MgH2 and their catalytic influences on the hydrogen storage properties of MgH2 were investigated. Results showed that the 15 wt% HfCl4-doped MgH2 sample was the best composite to enhance the hydrogen storage performance of MgH2. The onset decomposition temperature of the 15 wt% HfCl4-doped MgH2 composite was decreased by ~75 °C compared to as-milled MgH2. Meanwhile, the desorption/absorption kinetic measurements showed an improvement compared to the undoped MgH2. From the Kissinger analysis, the apparent dehydrogenation activation energy was 167.0 kJ/mol for undoped MgH2 and 102.0 kJ/mol for 15 wt% HfCl4-doped MgH2. This shows that the HfCl4 addition reduced the activation energy of the hydrogen decomposition of MgH2. The desorption enthalpy change calculated by the van't Hoff equation showed that the addition of HfCl4 to MgH2 did not affect the thermodynamic properties. Scanning electron microscopy showed that the size of the MgH2 particles decreased and there was less agglomeration after the addition of HfCl4. It is believed that the decrease in the particle size and in-situ generated MgCl2 and Hf-containing species had synergistic catalytic effects on enhancing the hydrogen storage properties of the HfCl4-doped MgH2 composite. © 2020 Hydrogen Energy Publications LLC","Magnesium hydride (MgH2) is the best candidate material to store hydrogen in the solid-state form owing to its advantages such as good reversibility, high hydrogen storage capacity (7.6 wt%), low raw material cost and abundance in the earth. Nevertheless, slow desorption/absorption kinetics and high thermodynamic stability are two issues that have constrained the commercialization of MgH2 as a solid-state hydrogen storage material.",_
!151,"In the era of chaotic global warming and climate change, the hunt for alternative energy sources for fossil fuel has become an intense topic. The most viable clean, green and alternative energy carrier is hydrogen that can meet out the challenges posed towards energy scarcity. So, the present work focus on the effective storing of hydrogen on non-carboneous (Ah-BN) and hydrogen rich metal hydride (NaBH4) based storage medium. where a facile chemical impregnated method was adopted for the preparation of NaBH4/Ah-BN nanocomposite. The structural, morphological, elemental composition and specific surface area analysis of the prepared NaBH4/Ah-BN nanocomposite confirms the presence of NaBH4 wrapped around Ah-BN and enhanced specific surface area of 154.4 m2 g −1 (NaBH4/Ah-BN) from 68.2 m2 g −1 (Ah-BN). The presence of NaBH4 not only increases the specific surface area but also increases the pore volume thereby creating more defects. In contrast the presence of Ah-BN drastically reduces the decomposition temperature of NaBH4. The amount of stored hydrogen (Sievert's-like hydrogenation setup) was 3.8 wt% at 119 °C and the binding energy falls in the recommended range (0.33 −0.50 eV) of US-Department of Energy (DOE) 2025 targets. All the thermal analysis [thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC) and temperature-programmed desorption (TPD)] ensures the two-step dehydrogenation for NaBH4/Ah-BN. Moreover, the utilization of NaBH4/Ah-BN as an electrode to store hydrogen electrochemically reveals the attainment of 2550 mAh/g discharge capacity during 15 cycles that equals to 4.10 wt% hydrogen storage capacity. Hence, these excellent characteristics proved that the prepared NaBH4/Ah-BN nanocomposite may serve as an excellent weakly chemisorbed hydrogen storage system and electrode material to store hydrogen electrochemically in the realm of Hydrogen Fuel cells. © 2020 Elsevier B.V.","where a facile chemical impregnated method was adopted for the preparation of NaBH4/Ah-BN nanocomposite. Moreover, the utilization of NaBH4/Ah-BN as an electrode to store hydrogen electrochemically reveals the attainment of 2550 mAh/g discharge capacity during 15 cycles that equals to 4.10 wt% hydrogen storage capacity.",_
!152,"Magnesium-based hydrogen storage materials are considered as one of the most promising candidates for solid state hydrogen storage due to their advantages of high hydrogen capacity, excellent reversibility and low cost. In this paper, Mg91.4Ni7Y1.6 and Mg92.8Ni2.4Y4.8 alloys were prepared by melting and ball milling. Their microstructures and phases were characterized by X-ray diffraction, scanning electron microscope and transmission electron microscope, and hydrogen absorbing and desorbing properties were tested by the high pressure gas adsorption apparatus and differential scanning calorimetry (DSC). In order to estimate the activation energy and growth mechanism of alloy hydride, the JMAK, Arrhenius and Kissinger methods were applied for calculation. The hydrogen absorption content of Mg92.8Ni2.4Y4.8 alloy reaches 3.84 wt.% within 5 min under 350 ℃, 3 MPa, and the maximum hydrogen capacity of the alloy is 4.89 wt.% in same condition. However, the hydrogen absorption of Mg91.4Ni7Y1.6 alloy reaches 5.78 wt.% within 5 min, and the maximum hydrogen absorption of the alloy is 6.44 wt.% at 350 ℃ and 3 MPa. The hydrogenation activation energy of Mg91.4Ni7Y1.6 alloy is 25.4 kJ/mol H2, and the enthalpy and entropy of hydrogen absorption are -60.6 kJ/mol H2 and 105.5 J/K/mol H2, separately. The alloy begins to dehydrogenate at 210 ℃, with the dehydrogenation activation energy of 87.7 kJ/mol H2. By altering the addition amount of Ni and Y elements, the 14H-LPSO phase with smaller size and ternary eutectic areas with high volume fraction are obtained, which provides more phase boundaries and catalysts with better dispersion, and there are a lot of fine particles in the alloy, these structures are beneficial to enhance the hydrogen storage performance of the alloys. © 2021","In order to estimate the activation energy and growth mechanism of alloy hydride, the JMAK, Arrhenius and Kissinger methods were applied for calculation. By altering the addition amount of Ni and Y elements, the 14H-LPSO phase with smaller size and ternary eutectic areas with high volume fraction are obtained, which provides more phase boundaries and catalysts with better dispersion, and there are a lot of fine particles in the alloy, these structures are beneficial to enhance the hydrogen storage performance of the alloys.",_
!153,"MgH2 is one of the most promising materials for solid-state hydrogen storage, but its slow kinetics and relatively high dehydrogenation temperature have yet to be overcome. We have theoretically investigated surface energy and surface H vacancy formation on various MgH2 surfaces, including all possible H vacancy configurations in the studied size of MgH2(110), (100), (101), and (001), up to (3 × 2), (2 × 3), (2 × 2) and (2 × 2) slabs respectively, based on density functional theory. Consequently, the hydrogen diffusion paths on the surfaces are also studied. The most unstable surface, MgH2(001), has the most drastic change in vacancy formation energy. The relative high barriers for vacancy H formation, especially on the most stable surface, MgH2(110), reflect the slow kinetics of H release. The introduction of vacancy into MgH2 surfaces often induces defect levels in the energy-gap region. In general, the release of surface H atoms exhibits a pronounced dependence on the surface stability and the concentration of surface H vacancy, in line with the remarkable effect of ball milling in experiments. © 2021 Elsevier B.V.","MgH2 is one of the most promising materials for solid-state hydrogen storage, but its slow kinetics and relatively high dehydrogenation temperature have yet to be overcome. We have theoretically investigated surface energy and surface H vacancy formation on various MgH2 surfaces, including all possible H vacancy configurations in the studied size of MgH2(110), (100), (101), and (001), up to (3 × 2), (2 × 3), (2 × 2) and (2 × 2) slabs respectively, based on density functional theory.",_
!154,"Hydrogen has been long known to provide a solution toward clean energy systems. With this notion, many efforts have been made to find new ways of storing hydrogen. As a result, decades of studies has led to a wide range of hydrides that can store hydrogen in a solid form. Applications of these solid-state hydrides are well-suited to stationary applications. However, the main challenge arises in making the selection of the Metal Hydrides (MH) that are best suited to meet application requirements. Herein, we discuss the current state-of-art in controlling the properties of room temperature (RT) hydrides suitable for stationary application and their long term behavior in addition to initial activation, their limitations and emerging trends to design better storage materials. The hydrogen storage properties and synthesis methods to alter the properties of these MH are discussed including the emerging approach of high-entropy alloys. In addition, the integration of intermetallic hydrides in vessels, their operation with fuel cells and their use as thermal storage is reviewed. © Copyright © 2021 Modi and Aguey-Zinsou.","With this notion, many efforts have been made to find new ways of storing hydrogen. Herein, we discuss the current state-of-art in controlling the properties of room temperature (RT) hydrides suitable for stationary application and their long term behavior in addition to initial activation, their limitations and emerging trends to design better storage materials.",_
!155,"LiBH4 is a promising candidate for solid state hydrogen storage, however, it still suffers from high hydrogen desorption temperature, harsh hydrogen absorption conditions, and poor reversibility, which hinder its practical development. In this paper, a novel synthetic strategy of heat treating a LiBH4 and Ti(OEt)4 mixture is employed to prepare LiBH4 system with TiO in-situ introduced. With an optimized TiO content of 0.06 in molar fraction, the LiBH4-0.06TiO system shows onset and peak dehydrogenation temperatures of 240 °C and 340 °C, respectively, which are 140 °C and 90 °C lower than those of the pure LiBH4. The LiBH4-0.06TiO system can rapidly release 9 wt% H2 after dwelling at 400 °C for 10 min. The hydrogenation of the dehydrogenation product initiates at 150 °C, and a capacity of 9 wt% is reached after isothermal dwelling at 500 °C under 50 bar of H2 for 100 min. The capacity retention of the system can reach 74.4% after 10 cycles, indicating a favorable reversibility. With the introduction of TiO, the apparent dehydrogenation activation energy of the system is evidently reduced, and the formation of Li2B12H12, a highly thermal stable intermediate phase, is greatly suppressed. In addition, the aggregation is evidently alleviated. All of these contribute to the enhanced dehydrogenation kinetics and reversibility. TiO reacts with LiBH4, forming Li3BO3 and TiH2 after the initial dehydrogenation, which play significant catalytic effect to LiBH4. © 2022 Elsevier B.V.","The LiBH4-0.06TiO system can rapidly release 9 wt% H2 after dwelling at 400 °C for 10 min. TiO reacts with LiBH4, forming Li3BO3 and TiH2 after the initial dehydrogenation, which play significant catalytic effect to LiBH4.",_
!156,"A gas-to-power (GtoP) system for power outages is digitally modeled and experimentally developed in this work. The design includes a solid-state hydrogen storage system based on TiFeMn as a hydride forming alloy (5 tanks, total capacity: 110 g H2) and an air-cooled fuel cell (maximum power: 1.6 kW). In an emergency use case of the system, hydrogen is supplied to the fuel cell, and the waste heat coming from the exhaust air of the fuel cell is used for the endothermic dehydrogenation reaction of the metal hydride. This GtoP system shows fast, stable, and reliable responses from 149 W to 596 W under constant and dynamic conditions. The developed model is based on a network approach, and it is validated under static and dynamic power load scenarios, showing excellent agreement with the experimental results. © 2022 Proceedings of WHEC 2022 - 23rd World Hydrogen Energy Conference: Bridging Continents by H2. All rights reserved.","A gas-to-power (GtoP) system for power outages is digitally modeled and experimentally developed in this work. The developed model is based on a network approach, and it is validated under static and dynamic power load scenarios, showing excellent agreement with the experimental results.",_
!157,"A general problem when designing functional nanomaterials for energy storage is the lack of control over the stability and reactivity of metastable phases. Using the high-capacity hydrogen storage candidate LiAlH4 as an exemplar, we demonstrate an alternative approach to the thermodynamic stabilization of metastable metal hydrides by coordination to nitrogen binding sites within the nanopores of N-doped CMK-3 carbon (NCMK-3). The resulting LiAlH4@NCMK-3 material releases H2 at temperatures as low as 126 °C with full decomposition below 240 °C, bypassing the usual Li3AlH6 intermediate observed in bulk. Moreover, >80% of LiAlH4 can be regenerated under 100 MPa H2, a feat previously thought to be impossible. Nitrogen sites are critical to these improvements, as no reversibility is observed with undoped CMK-3. Density functional theory predicts a drastically reduced Al-H bond dissociation energy and supports the observed change in the reaction pathway. The calculations also provide a rationale for the solid-state reversibility, which derives from the combined effects of nanoconfinement, Li adatom formation, and charge redistribution between the metal hydride and the host.  © 2021 American Chemical Society. All rights reserved.","A general problem when designing functional nanomaterials for energy storage is the lack of control over the stability and reactivity of metastable phases. Nitrogen sites are critical to these improvements, as no reversibility is observed with undoped CMK-3.",_
!158,"After various attempts, we present a new alkaline-earth derivative of hydrazine borane (N2H4BH3, HB), magnesium hydrazinidoborane (Mg(N2H3BH3)2, Mg(HB)2, 10.5 wt % H), that was undoubtedly identified by FTIR and 11B MAS NMR spectroscopy. Mg(HB)2 was obtained by an alternative synthesis route, which is the reaction between HB and di-n-butylmagnesium in THF. The dehydrogenation properties of this compound were evaluated by two different approaches: an “open” system by thermogravimetric analysis and differential scanning calorimetry, and in a closed system, by heating the compound under isothermal conditions. Different results were obtained depending on the approach. Unlike other boron- and nitrogen-based compounds, it is likely that when Mg(HB)2 is heated in a closed system, the dehydrogenation is limited and it occurs mainly due to the homopolar interaction between the protic hydrogen atoms of the molecule. Also, Mg(HB)2 presents a contrasting thermal behavior in comparison with previous HB derivatives. In addition, a characterization by X-ray photoelectron spectroscopy was performed, and we detected instability of Mg(HB)2 when it was irradiated with the X-ray beam. All of these results are presented and discussed in the context of materials for hydrogen storage in the solid-state. © 2021 Hydrogen Energy Publications LLC","After various attempts, we present a new alkaline-earth derivative of hydrazine borane (N2H4BH3, HB), magnesium hydrazinidoborane (Mg(N2H3BH3)2, Mg(HB)2, 10.5 wt % H), that was undoubtedly identified by FTIR and 11B MAS NMR spectroscopy. In addition, a characterization by X-ray photoelectron spectroscopy was performed, and we detected instability of Mg(HB)2 when it was irradiated with the X-ray beam.",_
!159,"The anticipated energy crisis due to the extensive use of limited stock fossil fuels forces the scientific society for find prompt solution for commercialization of hydrogen as a clean source of energy. Hence, convenient and efficient solid-state hydrogen storage adsorbents are required. Additionally, the safe commercialization of huge reservoir natural gas (CH4) as an on-board vehicle fuel and alternative to gasoline due to its environmentally friendly combustion is also a vital issue. To this end, in this study we report facile synthesis of polymer-based composites for H2 and CH4 uptake. The cross-linked polymer and its porous composites with activated carbon were developed through in-situ synthesis method. The mass loadings of activated carbon were varied from 7 to 20 wt%. The developed hybrid porous composites achieved high specific surface area (SSA) of 1420 m2/g and total pore volume (TPV) of 0.932 cm3/g as compared to 695 m2/g and 0.857 cm3/g for pristine porous polymer. Additionally, the porous composite was activated converted to a highly porous carbon material achieving SSA and TPV of 2679 m2/g and 1.335 cm3/g, respectively. The H2 adsorption for all developed porous materials was studied at 77 and 298 K and 20 bar achieving excess uptake of 4.4 wt% and 0.17 wt% respectively, which is comparable to the highest reported value for porous carbon. Furthermore, the developed porous materials achieved CH4 uptake of 8.15 mmol/g at 298 K and 20 bar which is also among the top reported values for porous carbon. © 2020 Hydrogen Energy Publications LLC","Additionally, the safe commercialization of huge reservoir natural gas (CH4) as an on-board vehicle fuel and alternative to gasoline due to its environmentally friendly combustion is also a vital issue. The cross-linked polymer and its porous composites with activated carbon were developed through in-situ synthesis method.",_
!160,"Activated carbon, as one type of hydrogen storage material have long been attracted by a measure of researchers. Some of the activated carbon's properties may fall short compared with other materials; their characteristics like high surface area, easy-to-prepare, pretty small diameters, however, keep their status as one of the best choices for hydrogen storage. Carbon nanotube is considered as a promising candidate for solid-state hydrogen storage, and there is quite much research have been conducted to synthesize low-cost carbon nanotube with low absorption temperatures, high gravimetric and volumetric hydrogen storage densities, flexibility, good resistance to oxidation, high hardness, good reversibility and cyclic ability and moderate thermodynamic stability. Carbon fiber has shown its unique advantages among many other solid-state hydrogen storage materials. Carbon fiber might be the best for hydrogen storage since its low gas-solid interaction, tunable texture, surface area, high pore volume and excellent chemical and thermal stability. Additionally, the carbon fiber could also control its pore size for better absorption of a great number of hydrogen molecules. Based on several indexes, this literature introduce above three types of solid-state hydrogen materials, which hopefully are able to be favorable to further researches on relevant fields. © Published under licence by IOP Publishing Ltd.","Some of the activated carbon's properties may fall short compared with other materials; their characteristics like high surface area, easy-to-prepare, pretty small diameters, however, keep their status as one of the best choices for hydrogen storage. Carbon fiber has shown its unique advantages among many other solid-state hydrogen storage materials.",_
!161,"For safe storage with higher density, solid hydrogen storage modes are preferred over gaseous and liquid modes. Solid state materials have range of variety, available for hydrogen storage; like metal hydride, alanates, borohydrides and carbon based materials such as, fullerenes, graphene, carbon nanotubules, etc. Metal hydrides can be further categorized into AB5, AB2/A2B and AB types. Metal hydrides have large applications as stationary storage of hydrogen, fuel bed for vehicles in transportation sector, Nickel-metal hydride battery, heat engine, heat pump, compressor, separator for purification of hydrogen and many more. A metal hydride is characterized by hydrogenation properties of hydrogen storage capacity, activation process, p-c isotherms, operating temperature-pressure, heat of formation, kinetics and cyclic stability. Therefore, to cater the need of a particular application, specific metal hydride is developed with well define hydrogenation characteristics. Present communication deals with the development in AB5-type metal hydride to serve the society as energy material. The parent AB5-type alloy has certain fix hydrogenation properties, which are not satisfactory for all the application point of view.Therefore the parent AB5-type alloy (LaNÍ5/MmNÍ5) is needed to be tailored for improved hydrogenation properties. For tailoring, either another element is substituted at the site of 'A' or/and 'B' or a different synthesis route is followed.In present chapter, various types of modifications done in the © 2021 by Nova Science Publishers, Inc. All rights reserved.","Therefore, to cater the need of a particular application, specific metal hydride is developed with well define hydrogenation characteristics. For tailoring, either another element is substituted at the site of 'A' or/and 'B' or a different synthesis route is followed.In present chapter, various types of modifications done in the © 2021 by Nova Science Publishers, Inc. All rights reserved.",_
!162,"The problem of providing compact and safe storage solutions for hydrogen in solid-state materials is demanding and challenging. The storage solutions for hydrogen required high-capacity storage technologies, which preferably operate at low pressures and have good performances in the kinetics of absorption/desorption. Metal hydrides such as magnesium hydride (MgH2) are promising candidates for such storage solutions, but several drawbacks including high onset desorption temperature (>400°C) and slow sorption kinetics need to be overcome. In this study, we reviewed the recent developments in the hydrogen storage performance development of MgH2 and found that the destabilization concept has been extensively explored. Lithium alanate or LiAlH4 has been used as a destabilizing agent in MgH2–LiAlH4 (Mg–Li–Al) due to its high capacity of hydrogen, which is 10.5 wt.%, and low onset desorption temperature (∼150°C). In this article, a review of the recent advances in the Mg–Li–Al system for the solid-state hydrogen storage material is studied. We discussed the effect of the ratio of MgH2 and LiAlH4, milling time, and additives in the Mg–Li–Al system. After the destabilization concept was introduced, the onset of the desorption temperature and activation energy of MgH2 were reduced, and the sorption properties improved. Further study showed that the intermetallic alloys of Li0.92Mg4.08 and Mg17Al12 that were formed in situ during the dehydrogenation process provide synergetic thermodynamic and kinetic destabilization in the Mg-Li-Al composite system. De/rehydrogenation measurements indicate that the intermetallic alloys of Li0.92Mg4.08 and Mg17Al12 were fully reversibly absorbed and desorbed hydrogen. Next, the remaining challenges and a possible development strategy of the Mg–Li–Al system are analyzed. This review is the first systematic study that focuses on the recent advances in the Mg–Li–Al system for storage solutions for hydrogen in solid-state materials. Copyright © 2022 Sazelee, Ali, Yahya, Mustafa, Halim Yap, Mohamed, Ghazali, Suwarno and Ismail.","Lithium alanate or LiAlH4 has been used as a destabilizing agent in MgH2–LiAlH4 (Mg–Li–Al) due to its high capacity of hydrogen, which is 10.5 wt.%, and low onset desorption temperature (∼150°C). Copyright © 2022 Sazelee, Ali, Yahya, Mustafa, Halim Yap, Mohamed, Ghazali, Suwarno and Ismail.",_
!163,"Magnesium hydride (MgH2) is one of the most promising materials for solid state hydrogen storage, but overly stable thermodynamics and sluggish kinetics of hydrogenation and dehydrogenation hinders its application. In this study, Mg90Al10 was prepared by hydriding combustion synthesis (HCS), and then various Ti-based compounds (Ti, TiH2, TiO2 and TiF3) were introduced into Mg90Al10 by ball milling. Mg90Al10 + 10 wt% TiF3 displays the most excellent dehydrogenation property compared with those doped with other Ti-based compounds. For instance, due to the addition of 10 wt% TiF3, the peak dehydrogenation temperature and the apparent dehydrogenation activation energy of the composite are 86 °C and 77.1 kJ/mol lower than those of Mg90Al10 (364 °C and 155.95 kJ/mol). In addition, the catalytic effect of TiF3 on the hydrogen storage properties of Mg90Al10 has been investigated in detail. Except for the unreacted TiF3, Al3Ti and MgF2 can be found during the first dehydrogenation process and remain stable in the subsequent de/hydrogenation cycles, which can act as the active sites to accelerate the hydrogen dissociation and recombination. Therefore, the excellent hydrogen storage properties of Mg90Al10 + 10 wt% TiF3 can be attributed to the catalytic effect of TiF3, in-situ formed Al3Ti and MgF2. Our result is very significant to emphasize the practical application of the Mg-Al hydrogen storage alloys. © 2022 Elsevier B.V.","Magnesium hydride (MgH2) is one of the most promising materials for solid state hydrogen storage, but overly stable thermodynamics and sluggish kinetics of hydrogenation and dehydrogenation hinders its application. In this study, Mg90Al10 was prepared by hydriding combustion synthesis (HCS), and then various Ti-based compounds (Ti, TiH2, TiO2 and TiF3) were introduced into Mg90Al10 by ball milling.",_
!164,"The development of efficient and low-cost solid-state hydrogen storage materials remains a significant challenge. Carbonaceous-based nanostructures supported with metal catalysts have shown promising results toward hydrogen storage. Here, we report on a facile one-pot synthesis of a novel three-dimensional (3D) reduced graphene oxide (rGO) and expanded graphite (EG) nanocomposite (NC) decorated with Pd nanoparticles (NPs) as hydrogen storage media. The effects of the electrochemically active surface area and surface oxygen groups of the as-synthesized Pd/rGO-EG on electrochemical hydrogen uptake and release were investigated in detail. For comparison, five Pd/rGO-EG NCs with rGO/EG mass ratios of 3:1, 2:1, 1:1, 1:2, and 1:3 were prepared. All the Pd/rGO-EG NCs exhibited a much higher hydrogen storage capacity than Pd/rGO and Pd/EG. Among them, Pd/rGO-EG(1:1) showed the highest hydrogen uptake and release (9850 mC cm-2 mg-1), which was over six- and twofold increase compared to Pd/rGO (1480 mC cm-2 mg-1) and Pd/EG (4290 mC cm-2 mg-1), respectively. The synergistic effects of the rGO-EG NC could be attributed to the formation of the 3D graphene-based structure, a minimal degree of sheet stacking, and homogeneous Pd NP dispersion. The formed Pd/rGO-EG NC possessed significant interfacial active sites, thereby greatly enhancing its performance for hydrogen uptake and release. The influence of the applied electrode potential on the formation of α-phase and β-phase nucleation in the as-synthesized materials was further investigated. The concepts and strategies discussed in this study contribute new avenues toward future carbon-based material designs for a sustainable hydrogen economy and energy applications.  © 2021 American Chemical Society. All rights reserved.","The development of efficient and low-cost solid-state hydrogen storage materials remains a significant challenge. The formed Pd/rGO-EG NC possessed significant interfacial active sites, thereby greatly enhancing its performance for hydrogen uptake and release.",_
!165,"Magnesium hydride (MgH2) is considered as a promising solid-state hydrogen storage material due to its high hydrogen storage mass density and environmental friendliness. However, its sluggish dehydrogenation kinetics are still the bottleneck that restricts practical applications. To address this challenge, very recent pioneering experiments found that MgH2/single-atom catalyst (MgH2/SAC) heterojunctions can be promising candidates for hydrogen storage. However, the reaction mechanism and design guideline were still not well understood. Herein, we design and analyze MgH2/SAC heterojunction systems including nine 3d transition metals, using spin-polarized density functional theory calculations with van der Waals corrections. We found that the energy barriers of MgH2 dehydrogenation are significantly reduced by 0.51-2.22 eV through the promotion effects of a heterojunction. Using ab initio molecular dynamics simulations, these promotion effects were analyzed in depth based on the observation of hydrogen diffusion behaviors. To provide further insights, the electron localization function, charge density difference, hydrogen adsorption energy, system electronegativity, d-band center, and crystal orbital Hamilton population were comprehensively analyzed to understand the origin of the high performance of MgH2/SACs. In particular, we found that the system electronegativity of SACs can act as an effective descriptor that predicts the dehydrogenation energy barriers. Most importantly, this study provides important design guidelines of a brand-new type of MgH2/SAC material and a promising solution to the sluggish kinetics of MgH2 dehydrogenation in hydrogen storage. © 2022 The Royal Society of Chemistry.","Herein, we design and analyze MgH2/SAC heterojunction systems including nine 3d transition metals, using spin-polarized density functional theory calculations with van der Waals corrections. Using ab initio molecular dynamics simulations, these promotion effects were analyzed in depth based on the observation of hydrogen diffusion behaviors.",_
!166,"This paper studies on the preparation of the alanate-borohydride combined system, LiAlH4 + Mg(BH4)2 with diverse molar ratios (1:1, 1:2, and 2:1) using the ball milling technique. The findings show that there is a mutual destabilization between the hydrides where the newly combined system has superior hydrogen storage performances as opposed to the unary components (LiAlH4 and Mg[BH4]2). Analysis on the initial decomposition temperature and isothermal de/hydrogenation kinetics has proven that the 2LiAlH4 + Mg(BH4)2 system possesses better performance. In an endeavor to ameliorate the performances of the hydrogen storage of 2LiAlH4 + Mg(BH4)2, the destabilized system was doped with TiF3. Three major steps of desorption were detected during the heating process in the 2LiAlH4 + Mg(BH4)2 system with and without the addition of TiF3, which are correlated to the decomposition of Mg(AlH4)2, MgH2 and LiBH4. It is found that 2LiAlH4 + Mg(BH4)2 + 5 wt.% TiF3 has decreased the initial decomposition temperature at about 60°C, which is 55°C lower than the non-catalyzed 2LiAlH4 + Mg(BH4)2 system. The isothermal absorption/desorption kinetics of the 2LiAlH4 + Mg(BH4)2 system have also been enhanced by the addition of TiF3. The activation energy for Mg(AlH4)2-, MgH2-, and LiBH4-relevant decomposition after doped 2LiAlH4 + Mg(BH4)2 with TiF3 are reduced to 36.5, 23.3, and 17.6 kJ mol−1. Studies on the structural characteristics analysis of the 2LiAlH4 + Mg(BH4)2 + TiF3 sample hint to the fact that the formation of the MgF2, LiF, TiH2 and Ti-Al species, during desorption, is the main responsible factor for the observed thermodynamics change of the reactions by modifying the dehydrogenation and hydrogenation pathway. The catalytic role played by TiF3 may have encouraged the interaction between Mg(AlH4)2, MgH2, and LiBH4, further ameliorate the de/hydrogenation of the 2LiAlH4 + Mg(BH4)2 + TiF3 destabilized system. © 2020 John Wiley & Sons Ltd","Analysis on the initial decomposition temperature and isothermal de/hydrogenation kinetics has proven that the 2LiAlH4 + Mg(BH4)2 system possesses better performance. It is found that 2LiAlH4 + Mg(BH4)2 + 5 wt.% TiF3 has decreased the initial decomposition temperature at about 60°C, which is 55°C lower than the non-catalyzed 2LiAlH4 + Mg(BH4)2 system.",_
!167,"Hydrogen storage and delivery technology is still a bottleneck in the hydrogen industry chain. Among all kinds of hydrogen storage methods, light-weight solid-state hydrogen storage (LSHS) materials could become promising due to its intrinsic high hydrogen capacity. Hydrolysis reaction of LSHS materials occurs at moderate conditions, indicating the potential for portable applications. At present, most of review work focuses on the improvement of material performance, especially the catalysts design. This part is important, but the others, such as operation modes, are also vital to to make full use of material potential in the practical applications. Different operation modes of hydrolysis reaction have an impact on hydrogen capacity to various degrees. For example, hydrolysis in solution would decrease the hydrogen capacity of hydrogen generator to a low value due to the excessive water participating in the reaction. Therefore, application-oriented operation modes could become a key problem for hydrolysis reaction of LSHS materials. In this paper, the operation modes of hydrolysis reaction and their practical applications are mainly reviewed. The implements of each operation mode are discussed and compared in detail to determine the suitable one for practical applications with the requirement of high energy density. The current challenges and future directions are also discussed. © 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences","Different operation modes of hydrolysis reaction have an impact on hydrogen capacity to various degrees. In this paper, the operation modes of hydrolysis reaction and their practical applications are mainly reviewed.",_
!168,"Despite myriads of mathematical and experimental studies using various heat exchanger-metal hydride assemblies, an adept comparison of reactors on standard performance defining parameters, i.e., reactor weight, external energy utilization, and alloy material, are not studied or reported for industrial storage containers and onboard applications. This lacuna is a critical barrier in developing efficacious hydrogen storage reactors for various applications. This article chronicles the 3-D design and optimization of three basic heat exchanger setups of solid-state hydrogen storage systems (shell and tube, spiral tube, and tubular) on critical parameters. For 5 kg LaNi5, a tubular design with small tube diameters has resulted in a shorter reaction time (120 s) for 90% saturation at 303 K and 15 bar inlet conditions; however, the reactor's gravimetric density was exceptionally high. In contrast, the reactor with three spiral tubes accomplished an exemplary reaction rate at a reasonable gravimetric density. This spiral arrangement became the base for developing a novel reactor that integrated heat pipes to reduce the sorption time. The proposed design achieved a specific output energy rate of 527 W/kg for 90% saturation in 366 s at a supply pressure of 15 bar, which is 23.7% higher than the reactor without heat pipes. © 2022 Elsevier Ltd","This lacuna is a critical barrier in developing efficacious hydrogen storage reactors for various applications. In contrast, the reactor with three spiral tubes accomplished an exemplary reaction rate at a reasonable gravimetric density.",_
!169,"Lithium alanate (LiAlH4) is a material that can be potentially used for solid-state hydrogen storage due to its high hydrogen content (10.5 wt%). Nevertheless, a high desorption temperature, slow desorption kinetic, and irreversibility have restricted the application of LiAlH4 as a solid-state hydrogen storage material. Hence, to lower the decomposition temperature and to boost the dehydrogenation kinetic, in this study, we applied K2NiF6 as an additive to LiAlH4. The addition of K2NiF6 showed an excellent improvement of the LiAlH4 dehydrogenation properties. After adding 10 wt% K2NiF6, the initial decomposition temperature of LiAlH4 within the first two dehydrogenation steps was lowered to 90 °C and 156 °C, respectively, that is 50 °C and 27 °C lower than that of the аs-milled LiAlH4. In terms of dehydrogenation kinetics, the dehydrogenation rate of K2NiF6-doped LiAlH4 sample was significantly higher as compared to аs-milled LiAlH4. The K2NiF6-doped LiAlH4 sample can release 3.07 wt% hydrogen within 90 min, while the milled LiAlH4 merely release 0.19 wt% hydrogen during the same period. According to the Arrhenius plot, the apparent activation energies for the desorption process of K2NiF6-doped LiAlH4 are 75.0 kJ/mol for the first stage and 88.0 kJ/mol for the second stage. These activation energies are lower compared to the undoped LiAlH4. The morphology study showed that the LiAlH4 particles become smaller and less agglomerated when K2NiF6 is added. The in situ formation of new phases of AlNi and LiF during the dehydrogenation process, as well as a reduction in particle size, is believed to be essential contributors in improving the LiAlH4 dehydrogenation characteristics. © 2022 Hydrogen Energy Publications LLC","These activation energies are lower compared to the undoped LiAlH4. The in situ formation of new phases of AlNi and LiF during the dehydrogenation process, as well as a reduction in particle size, is believed to be essential contributors in improving the LiAlH4 dehydrogenation characteristics.",_
!170,"As classical BCC structure solid state hydrogen storage materials, vanadium-based solid solution alloys occupied a prominent position in the field of hydrogen storage materials due to their significant advantages such as the ability to absorb and desorb hydrogen with high capacity under moderate conditions. In this paper, RE-containing medium entropy BCC solid solution alloys were designed. The microstructure, phase composition and hydrogen storage properties of the medium entropy alloys were systematically studied. Microstructural analysis showed that nanoscale crystals were found in as-cast medium entropy alloys obtained by arc melting followed by natural cooling inside the furnace. This is different from the vanadium-based alloys that are often regarded as traditional coarse-grained alloys in the past decades. The V47Fe11Ti30Cr10RE2 alloys can be fully activated by one cycle of hydrogen ab/de-sorption after pretreatment. The kinetic test shows that the time required for the as-cast RE-containing medium entropy alloys hydrogen uptake to 90% saturation is less than 100 s at room temperature. The alloys exhibit very excellent hydrogen absorption kinetic properties than reported alloys takes at least about 300 s. This is due to the fact that the present alloys are composed of nanocrystals with numerous interfaces and grain boundaries, and these defects can act as good channels for the diffusion of hydrogen atoms. The V47Fe11Ti30Cr10Y2 alloy exhibits a maximum capacity of 3.41 wt% at 295 K. The thermodynamics of hydrogen ab/de-sorption and the hydrogen desorption under non-isothermal conditions were also studied in detail. © 2022 Elsevier B.V.","In this paper, RE-containing medium entropy BCC solid solution alloys were designed. The V47Fe11Ti30Cr10RE2 alloys can be fully activated by one cycle of hydrogen ab/de-sorption after pretreatment.",_
!171,"Hydrides have been used since a long time for solid-state hydrogen storage and electrochemical nickel-metal hydride batteries. Besides these applications, growing attention has been devoted to their development as anode materials, as well as solid electrolytes for Li-ion and other ion batteries. Herein, we review and summarize the recent advances of hydrides as negative electrodes for Ni-MH and A-ion batteries (A = Li, Na), and as electrolyte for all solid-state batteries (ASSB). Metallic hydrides such as intergrowth compounds are highlighted as the best compromise up to now for Ni-MH. Regarding anodes of Li-ion batteries, MgH2, especially its combination with TiH2, provides very promising results. Complex hydrides such as Li-borohydride and related closo-borates and monovalent carborate boron clusters appear to be very attractive as solid electrolytes for Li-based ASSB, whereas closo-hydroborate sodium salts and closo-carboborates are investigated for Na- and Mg-ASSB. Finally, further research directions are foreseen for hydrides in electrochemical applications. © 2021 Elsevier B.V.","Hydrides have been used since a long time for solid-state hydrogen storage and electrochemical nickel-metal hydride batteries. Regarding anodes of Li-ion batteries, MgH2, especially its combination with TiH2, provides very promising results.",_
!172,"In this investigation, we report the cyclic performance, microstructure and thermal properties of near eutectic Mg–Ni alloys with different Ni contents (4.4, 11.3 and 16.3 at%). The starting cast ingots are mechanically chipped to flakes of about 400 μm, all displaying composite structures characterized by a typical eutectic microstructure with rather coarse features (1–5 μm). The flakes are cycled 1000 times at 330 °C under 30/1 bar H2 for the absorption/desorption processes. The hydrogen storage capacity is maintained throughout the cycling: 5.09, 4.46 and 3.49 wt% H2 for Ni16.3, Ni11.3 and Ni4.4 (at%), respectively. No significant microstructural change is observed, indicating the excellent stability of the alloys at elevated temperatures. Nevertheless, a marked porosity, and spheroidal Mg2Ni clusters can be noted after cycling, however their exact contribution to reaction kinetics has yet to be fully elucidated. An attempt is made to estimate the dehydrogenation activation energy of Ni16.3, and the calculated value seems comparable to that obtained for an early cycling stage (10 cycles). In the light of the superior stability under cyclic service and the low decomposition temperature, the Mg–Mg2Ni system is shown to possess an excellent potential for long-term hydrogen and heat storage applications. © 2021 Hydrogen Energy Publications LLC","The starting cast ingots are mechanically chipped to flakes of about 400 μm, all displaying composite structures characterized by a typical eutectic microstructure with rather coarse features (1–5 μm). An attempt is made to estimate the dehydrogenation activation energy of Ni16.3, and the calculated value seems comparable to that obtained for an early cycling stage (10 cycles).",_
!173,"In stand-alone microgrids, by employing hydrogen storage coupled with fuel cell, multiple outputs such as electricity, heat, water, and fuel, can be achieved. This study presents an approach to optimize the size of different components of a solar photovoltaic field based microgrid configured with electrolyzer, fuel cell, hydrogen storage and battery bank. The optimum configuration is based on maximizing the utilization of electricity produced by the solar photovoltaic field. Two performance parameters, namely, Unmet Electric Load (fUL) and Excess Electricity (fEX) are defined. The monthly and annual performance of the microgrid is studied for diverse climatic conditions with five climatic zones across six Indian locations as example. As is obvious, the polygeneration microgrid gives the best performance at mountainous zone due to abundant solar radiation. The thermal effects due to sorption and desorption reactions of metal hydride hydrogen storage and fuel cell exhaust provide more than 50% of thermal load in each zone. Even though the optimized configuration can serve the electrical load demand of the different zones, the benefits of polygeneration are more pronounced for mountainous, humid subtropical and arid climatic zones, in that order. © Elsevier Ltd","This study presents an approach to optimize the size of different components of a solar photovoltaic field based microgrid configured with electrolyzer, fuel cell, hydrogen storage and battery bank. Two performance parameters, namely, Unmet Electric Load (fUL) and Excess Electricity (fEX) are defined.",_
!174,"This article reports the hydrogenation properties of several Mg–Mg2Ni composite specimens with increasing Ni content: 4.4, 11.3 (eutectic), and 16.3 (in at%). Mg–Mg2Ni composites were prepared by means of induction melting, followed by simple mechanical chipping of the casts. The hydrogenation and dehydrogenation reaction kinetics were studied, and reaction mechanisms were described by means of solid-gas reaction modeling. Absorption and desorption properties were evidenced to be diffusion controlled, with hydrogen diffusion through hydrided/dehydrided phases being the rate limiting step in most cases (the migration of metal/hydride interface at a constant velocity being rate-limiting in only few of them). The kinetics study was supported by a thorough thermal analysis to provide in-depth insights of the decomposition reaction. Hence, thermogravimetry (TG) and pressurized differential scanning calorimeter (PDSC) were combined to investigate the dehydrogenation properties such as hydrogen gravimetric density, reaction onset temperature, enthalpy and activation energy as a function of Ni content. Structural analysis included X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM) to discuss the structural stability and microstructural evolution as a function of cycles, notably during the activation procedure. Finally, cyclic performance was evaluated for 100 cycles, using a custom-made large-scale reactor to demonstrate scale-up feasibility. © 2020 Hydrogen Energy Publications LLC","This article reports the hydrogenation properties of several Mg–Mg2Ni composite specimens with increasing Ni content: 4.4, 11.3 (eutectic), and 16.3 (in at%). Absorption and desorption properties were evidenced to be diffusion controlled, with hydrogen diffusion through hydrided/dehydrided phases being the rate limiting step in most cases (the migration of metal/hydride interface at a constant velocity being rate-limiting in only few of them).",_
!175,"Nanomaterials are beginning to play an essential role in addressing the challenges associated with hydrogen production and storage. The outstanding physicochemical properties of nanomaterials suggest their applications in almost all technological breakthroughs ranging from catalysis, metal-organic framework, complex hydrides, etc. This study outlines the applications of nanomaterials in hydrogen production (considering both thermochemical, biological, and water splitting methods) and storage. Recent advances in renewable hydrogen production methods are elucidated along with a comparison of different nanomaterials used to enhance renewable hydrogen production. Additionally, nanomaterials for solid-state hydrogen storage are reviewed. The characteristics of various nanomaterials for hydrogen storage are compared. Some nanomaterials discussed include carbon nanotubes, activated carbon, metal-doped carbon-based nanomaterials, metal-organic frameworks. Other materials such as complex hydrides and clathrates are outlined. Finally, future research perspectives related to the application of nanomaterials for hydrogen production and storage are discussed. © 2022 Hydrogen Energy Publications LLC","Nanomaterials are beginning to play an essential role in addressing the challenges associated with hydrogen production and storage. The outstanding physicochemical properties of nanomaterials suggest their applications in almost all technological breakthroughs ranging from catalysis, metal-organic framework, complex hydrides, etc.",_
!176,"This article reports the hydrogenation properties of a TiFe0.85Cr0.15 alloy prepared by gas atomization on one hand, and vacuum arc-remelting on the other hand for demonstration and reference, respectively. To evidence the excellent potential of ternary alloying combined with gas atomization process for improving the first hydrogen absorption kinetics, both the atomized powders and the reference crushed ingots were exposed to air from 1 h to as long as 10 days. In spite of the resulting surface oxide layer formation, all specimens still absorbed hydrogen partly thanks to the presence of the C14 Laves phase. As expected, the first hydrogenation kinetics decreased with increasing air-exposure time, but atomized powders not only outperformed the reference counterparts but also remained quite competitive despite surface oxidation. The remarkable kinetic enhancement observed was attributed to the formation of an additional Ti2Fe phase, to an increased amount of C14 Laves phase, as well as to a fine microstructure resulting from the rapid cooling rate involved in gas atomization. Even though different absorption behaviors were observed for all samples, the reaction mechanisms derived from solid-gas reaction models were ascribed to interface- and diffusion-controlled 3D processes in the early and subsequent stage of the first hydrogenation, respectively. © 2022 The Authors","This article reports the hydrogenation properties of a TiFe0.85Cr0.15 alloy prepared by gas atomization on one hand, and vacuum arc-remelting on the other hand for demonstration and reference, respectively. As expected, the first hydrogenation kinetics decreased with increasing air-exposure time, but atomized powders not only outperformed the reference counterparts but also remained quite competitive despite surface oxidation.",_
!177,"Solid-state hydrogen storage covers a broad range of materials praised for their gravimetric, volumetric and kinetic properties, as well as for the safety they confer compared to gaseous or liquid hydrogen storage methods. Among them, AxBy intermetallics show outstanding performances, notably for stationary storage applications. Elemental substitution, whether on the A or B site of these alloys, allows the effective tailoring of key properties such as gravimetric density, equilibrium pressure, hysteresis and cyclic stability for instance. In this review, we present a brief overview of partial substitution in several AxBy alloys, from the long-established AB5 and AB2-types, to the recently attractive and extensively studied AB and AB3 alloys, including the largely documented solid-solution alloy systems. We not only present classical and pioneering investigations, but also report recent developments for each AxBy category. Special care is brought to the influence of composition engineering on desorption equilibrium pressure and hydrogen storage capacity. A simple overview of the AxBy operating conditions is provided, hence giving a sense of the range of possible applications, whether for low- or high-pressure systems. © 2020 by the authors.","We not only present classical and pioneering investigations, but also report recent developments for each AxBy category. Special care is brought to the influence of composition engineering on desorption equilibrium pressure and hydrogen storage capacity.",_
!178,"As a crucial link in the application of hydrogen for an alternative clean energy, light-weight solid-state hydrogen storage materials, such as metal hydrides and complex hydrides, attract ever-growing attention, and they have a great application potential due to their high hydrogen storage densities. Intensive research performed on modifications of the composition of the materials to improve their unfavorable kinetics, the thermodynamics, and reversibility, put forward higher requirements to the characterization methods to study in-depth mechanisms of the improved hydrogen absorption and desorption performance. Fortunately, due to the high scattering cross-section of hydrogen and deuterium, neutron scattering techniques, including neutron diffraction, inelastic neutron scattering, small-angle neutron scattering, and neutron total scattering technology, have become powerful tools for characterizing hydrogen storage mechanism of metal hydrides and complex hydrides. This review summarizes the recent important outcome in developing advanced solid-state hydrogen storage materials via taking advantage of neutron scattering techniques. © 2021 Elsevier B.V.","As a crucial link in the application of hydrogen for an alternative clean energy, light-weight solid-state hydrogen storage materials, such as metal hydrides and complex hydrides, attract ever-growing attention, and they have a great application potential due to their high hydrogen storage densities. This review summarizes the recent important outcome in developing advanced solid-state hydrogen storage materials via taking advantage of neutron scattering techniques.",_
!179,"A new route of materials synthesis, namely, high-temperature, high-pressure reactive planetary ball milling (HTPRM), is presented. HTPRM allows for the mechanosynthesis of materials at fully controlled temperatures of up to 450 °C and pressures of up to 100 bar of hydrogen. As an example of this application, a successful synthesis of magnesium hydride is presented. The synthesis was performed at controlled temperatures (room temperature (RT), 100, 150, 200, 250, 300, and 325 °C) while milling in a planetary ball mill under hydrogen pressure (>50 bar). Very mild milling conditions (250 rpm) were applied for a total milling time of 2 h, and a milling vial with a relatively small diameter (φ = 53 mm, V = ∼0.06 dm3) was used. The effect of different temperatures on the synthesis kinetics and outcome were examined. The particle morphology, phase composition, reaction yield, and particle size were measured and analysed by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry (DSC) techniques. The obtained results showed that increasing the temperature of the process significantly improved the reaction rate, which suggested the great potential of this technique for the mechanochemical synthesis of materials. © 2022 The Author(s)","A new route of materials synthesis, namely, high-temperature, high-pressure reactive planetary ball milling (HTPRM), is presented. The synthesis was performed at controlled temperatures (room temperature (RT), 100, 150, 200, 250, 300, and 325 °C) while milling in a planetary ball mill under hydrogen pressure (>50 bar).",_
!180,"Lithium borohydride (LiBH4) has been attracting extensive attention as an exemplary high-capacity complex hydride for solid-state hydrogen storage applications because of its high hydrogen capacities (18.5 wt% and 121 kg H2 m−3). However, the strong and highly directional covalent and ionic bonds within LiBH4 structure induce high desorption temperatures, slow kinetics, and poor reversibility, which make large-scale application impractical. To improve its hydrogen cycling performance, several strategies including cation/anion substitution, catalyst doping, reactive compositing, and nanoengineering, have been developed to tailor the thermodynamics and kinetics of hydrogen storage process. For example, largely reduced operation temperatures and remarkably improved hydrogen storage reversibility under moderate conditions have been achieved by the synergistic effect of nanostructuring and nanocatalysis. Herein, the state-of-the-art development of LiBH4-based hydrogen storage materials is summarized, including the basic physical and chemical properties, the principles of thermodynamic and kinetic manipulation and the strategies to improve hydrogen storage properties. The remaining challenges and the main directions of future research are also discussed. © 2021 The Authors. Advanced Energy and Sustainability Research published by Wiley-VCH GmbH.","Lithium borohydride (LiBH4) has been attracting extensive attention as an exemplary high-capacity complex hydride for solid-state hydrogen storage applications because of its high hydrogen capacities (18.5 wt% and 121 kg H2 m−3). To improve its hydrogen cycling performance, several strategies including cation/anion substitution, catalyst doping, reactive compositing, and nanoengineering, have been developed to tailor the thermodynamics and kinetics of hydrogen storage process.",_
!181,"Reversible hydrogen uptake and the metal/dielectric transition make the Mg/MgH2 system a prime candidate for solid-state hydrogen storage and dynamic plasmonics. However, high dehydrogenation temperatures and slow dehydrogenation hamper broad applicability. One promising strategy to improve dehydrogenation is the formation of metastable γ-MgH2. A nanoparticle (NP) design, where γ-MgH2 forms intrinsically during hydrogenation is presented and a formation mechanism based on transmission electron microscopy results is proposed. Volume expansion during hydrogenation causes compressive stress within the confined, anisotropic NPs, leading to plastic deformation of β-MgH2 via (301)β twinning. It is proposed that these twins nucleate γ-MgH2 nanolamellas, which are stabilized by residual compressive stress. Understanding this mechanism is a crucial step toward cycle-stable, Mg-based dynamic plasmonic and hydrogen-storage materials with improved dehydrogenation. It is envisioned that a more general design of confined NPs utilizes the inherent volume expansion to reform γ-MgH2 during each rehydrogenation. © 2021 The Authors. Advanced Materials published by Wiley-VCH GmbH","Volume expansion during hydrogenation causes compressive stress within the confined, anisotropic NPs, leading to plastic deformation of β-MgH2 via (301)β twinning. It is envisioned that a more general design of confined NPs utilizes the inherent volume expansion to reform γ-MgH2 during each rehydrogenation.",_
!182,"As the most abundant element in the world, hydrogen is a promising energy carrier and has received continuously growing attention in the last couple of decades. At the very moment, hydrogen fuel is imagined as the part of a sustainable and eco-friendly energy system, the “hydrogen grand challenge”. Among the large number of storage solutions, solid-state hydrogen storage is considered to be the safest and most efficient route for on-board applications via fuel cell devices. Notwithstanding the various advantages, storing hydrogen in a lightweight and compact form still presents a barrier towards the wide-spread commercialization of hydrogen technology. In this review paper we summarize the latest findings on solid-state storage solutions of different nonequilibrium systems which have been synthesized by mechanical routes based on severe plastic deformation. Among these deformation techniques, high-pressure torsion is proved to be a proficient method due to the extremely high applied shear strain that develops in bulk nanocrystalline and amorphous materials. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article.","In this review paper we summarize the latest findings on solid-state storage solutions of different nonequilibrium systems which have been synthesized by mechanical routes based on severe plastic deformation. Among these deformation techniques, high-pressure torsion is proved to be a proficient method due to the extremely high applied shear strain that develops in bulk nanocrystalline and amorphous materials.",_
!183,"Solid-state hydrogen storage materials often operate via transient, multistep chemical reactions at complex interfaces that are difficult to capture. Here, we use direct ab initio molecular dynamics simulations at accelerated temperatures and hydrogen pressures to probe the hydrogenation chemistry of the candidate material MgB2 without a priori assumption of reaction pathways. Focusing on highly reactive (101¯ 0) edge planes where initial hydrogen attack is likely to occur, we track mechanistic steps toward the formation of hydrogen-saturated BH4- units and key chemical intermediates, involving H2 dissociation, generation of functionalities and molecular complexes containing BH2 and BH3 motifs, and B-B bond breaking. The genesis of higher-order boron clustering is also observed. Different charge states and chemical environments at the B-rich and Mg-rich edge planes are found to produce different chemical pathways and preferred speciation, with implications for overall hydrogenation kinetics. The reaction processes rely on B-H bond polarization and fluctuations between ionic and covalent character, which are critically enabled by the presence of Mg2+ cations in the nearby interphase region. Our results provide guidance for devising kinetic improvement strategies for MgB2-based hydrogen storage materials, while also providing a template for exploring chemical pathways in other solid-state energy storage reactions.  © ","Solid-state hydrogen storage materials often operate via transient, multistep chemical reactions at complex interfaces that are difficult to capture. Here, we use direct ab initio molecular dynamics simulations at accelerated temperatures and hydrogen pressures to probe the hydrogenation chemistry of the candidate material MgB2 without a priori assumption of reaction pathways.",_
!184,"The chemistry of metal borohydrides and their derivatives has expanded signficantly during the past decade involving new compositions, structures, and the diversity of associated properties. Here we provide an overview of interesting results mainly from the past few years, discussed relative to previously published results. A range of new synthesis strategies has been developed to obtain pure samples, which has allowed very detailed structural, physical, and chemical investigations. A short overview of mono- and dimetallic borohydrides is provided, including a description of the complete series of rare-earth metal borohydrides and the recently discovered ammonium metal borohydrides, where the latter has attracted interest due to an extreme hydrogen content. Metal borohydrides appear to be the most promising class of materials to achieve high cationic conductivity of divalent metals, and particularly derivatives of metal borohydrides with neutral molecules show promise as future electrolytes for new types of solid-state batteries. Furthermore, metal borohydrides display a wide range of other properties, including optical, magnetic, semi conduction and possibly superconducting properties, and are also used as a new approach for carbon capture and conversion. The aim of the present review is to highlight new trends in properties and provide an outlook with possible future applications. Here, we focus on the more recently discovered materials. © 2021 The Authors","A range of new synthesis strategies has been developed to obtain pure samples, which has allowed very detailed structural, physical, and chemical investigations. A short overview of mono- and dimetallic borohydrides is provided, including a description of the complete series of rare-earth metal borohydrides and the recently discovered ammonium metal borohydrides, where the latter has attracted interest due to an extreme hydrogen content.",_
!185,"Hydrogen and ammonia are both potential energy carriers being considered for large scale energy transport. Sodium borohydride (NaBH4) has been widely applied as a potential solid-state hydrogen storage material. It can produce hydrogen gas and sodium metaborate (NaBO2) after hydrolysis with water at room temperature. The regeneration of NaBH4 from NaBO2 could significantly reduce the cost of NaBH4 and enable its wide-spread industrial use. In this work, we demonstrate a simple method for regenerating NaBH4 from NaBO2·4H2O using Mg2N3, which combines NaBH4 production with NH3 gas production in a single step at room temperature. NaBH4 is successfully synthesized from NaBO2·4H2O using the Mg3N2 reducing agent via ball milling under a hydrogen atmosphere. NaBH4 is formed at a 76.6% yield by planetary ball milling at 600 rpm under 40 bar hydrogen for 12 h. NH3 gas is also formed, which can be easily separated from the solid products. Therefore, this one-step process could produce two different types of carbon-free hydrogen carriers suitable for energy export from renewable sources. © 2022 Hydrogen Energy Publications LLC","It can produce hydrogen gas and sodium metaborate (NaBO2) after hydrolysis with water at room temperature. Therefore, this one-step process could produce two different types of carbon-free hydrogen carriers suitable for energy export from renewable sources.",_
!186,"With superior properties of Mg such as high hydrogen storage capacity (7.6 wt% H/MgH2), low price, and low density, Mg has been widely studied as a promising candidate for solid-state hydrogen storage systems. However, a harsh activation procedure, slow hydrogenation/dehydrogenation process, and a high temperature for dehydrogenation prevent the use of Mg-based metal hydrides for practical applications. For these reasons, Mg-based alloys for hydrogen storage systems are generally alloyed with other elements to improve hydrogen sorption properties. In this article, we have added Na to cast Mg–La alloys and achieved a significant improvement in hydrogen absorption kinetics during the first activation cycle. The role of Na in Mg–La has been discussed based on the findings from microstructural observations, crystallography, and first principles calculations based on density functional theory. From our results in this study, we have found that the Na doped surface of Mg–La alloy systems have a lower adsorption energy for H2 compared to Na-free surfaces which facilitates adsorption and dissociation of hydrogen molecules leading to improvement of absorption kinetic. The effect of Na on the microstructure of these alloys, such as eutectic refinement and a density of twins is not highly correlated with absorption kinetics. © 2021 Hydrogen Energy Publications LLC","With superior properties of Mg such as high hydrogen storage capacity (7.6 wt% H/MgH2), low price, and low density, Mg has been widely studied as a promising candidate for solid-state hydrogen storage systems. The role of Na in Mg–La has been discussed based on the findings from microstructural observations, crystallography, and first principles calculations based on density functional theory.",_
!187,"Solid-state hydrogen storage materials that are optimized for specific use cases could be a crucial facilitator of the hydrogen economy transition. Yet, the discovery of novel hydriding materials has historically been a manual process driven by chemical intuition or experimental trial and error. Data-driven materials' discovery paradigms provide an alternative to traditional approaches, whereby machine/statistical learning (ML) models are used to efficiently screen materials for desired properties and significantly narrow the scope of expensive/time-consuming first-principles modeling and experimental validation. Here, we specifically focus on a relatively new class of hydrogen storage materials, high entropy alloy (HEA) hydrides, whose vast combinatorial composition space and local structural disorder necessitate a data-driven approach that does not rely on exact crystal structures to make property predictions. Our ML model quickly screens hydride stability within a large HEA space and permits down selection for laboratory validation based on not only targeted thermodynamic properties but also secondary criteria such as alloy phase stability and density. To experimentally verify our predictions, we performed targeted synthesis and characterization of several novel hydrides that demonstrate significant destabilization (70× increase in equilibrium pressure, 20 kJ/molH2 decrease in desorption enthalpy) relative to the benchmark HEA hydride, TiVZrNbHfHx. Ultimately, by providing a large composition space in which hydride thermodynamics can be continuously tuned over a wide range, this work will enable efficient material selection for various applications, especially in areas such as metal hydride-based hydrogen compressors, actuators, and heat pumps.  © ","Yet, the discovery of novel hydriding materials has historically been a manual process driven by chemical intuition or experimental trial and error. Here, we specifically focus on a relatively new class of hydrogen storage materials, high entropy alloy (HEA) hydrides, whose vast combinatorial composition space and local structural disorder necessitate a data-driven approach that does not rely on exact crystal structures to make property predictions.",_
!188,"Despite high interest in compact and safe storage of hydrogen in the solid-state hydride form, the design of alloys that can reversibly and quickly store hydrogen at room temperature under pressures close to atmospheric pressure is a long-lasting challenge. In this study, first-principles calculations are combined with experiments to develop high-entropy alloys (HEAs) for room-temperature hydrogen storage. TixZr2-xCrMnFeNi (x = 0.4-1.6) alloys with the Laves phase structure and low hydrogen binding energies of -0.1 to -0.15 eV are designed and synthesized. The HEAs reversibly store hydrogen in the form of Laves phase hydrides at room temperature, while (de)hydrogenation pressure systematically reduces with increasing the zirconium fraction in good agreement with the binding energy calculations. The kinetics of hydrogenation are fast, the hydrogenation occurs without any activation or catalytic treatment, the hydrogen storage performance remains stable for at least 1000 cycles, and the storage capacity is higher than that for commercial LaNi5. The current findings demonstrate that a combination of theoretical calculations and experiments is a promising pathway to design new high-entropy hydrides with high performance for hydrogen storage. © 2022","Despite high interest in compact and safe storage of hydrogen in the solid-state hydride form, the design of alloys that can reversibly and quickly store hydrogen at room temperature under pressures close to atmospheric pressure is a long-lasting challenge. In this study, first-principles calculations are combined with experiments to develop high-entropy alloys (HEAs) for room-temperature hydrogen storage.",_
!189,"Ammonia borane NH3BH3 (AB), a material for solid-state hydrogen storage, can be nanosized by confinement into the porosity of a scaffold like mesoporous silica, carbon cryogel, graphene oxide, ZIF-8 as a metal organic framework, poly (methyl acrylate), boron nitride and manganese oxide. In doing so, nanosized AB is destabilized and shows better dehydrogenation properties than bulk AB in terms of temperature, activation energy, enthalpy and kinetics. Such improvements are due to the confinement-driven nanosizing effect, but not only. A catalytic effect may also have a contribution and, in some cases, it even overpasses the nanosizing effect. These effects are explained in detail herein. The present review aims at reporting the outcomes of the AB confinement strategy to help understand the advantages and to identify the limitations which are still not adequately defined. Based on this analysis, the challenges ahead are listed and discussed, and it appears that there are new opportunities to explore. Though nanosized AB is not mature enough for implementation, it has the potential to be developed further. Avenues worth exploring are given. © 2020 Hydrogen Energy Publications LLC","Such improvements are due to the confinement-driven nanosizing effect, but not only. Though nanosized AB is not mature enough for implementation, it has the potential to be developed further.",_
!190,"The design of multinary solid-state material systems that undergo reversible phase changes via changes in temperature and pressure provides a potential means of safely storing hydrogen. However, fully mapping the stabilities of known or newly targeted compounds relative to competing phases at reaction conditions has previously required many stringent experiments or computationally demanding calculations of each compound's change in Gibbs energy with respect to temperature, G(T). In this work, we have extended the approach of constructing chemical potential phase diagrams based on ΔGf(T) to enable the analysis of phase stability at non-zero temperatures. We first performed density functional theory calculations to compute the formation enthalpies of binary, ternary, and quaternary compounds within several compositional spaces of current interest for solid-state hydrogen storage. Temperature effects on solid compound stability were then accounted for using our recently introduced machine learned descriptor for the temperaturedependent contribution Gδ(T) to the Gibbs energy G(T). From these Gibbs energies, we evaluated each compound's stability relative to competing compounds over a wide range of conditions and show using chemical potential and composition phase diagrams that the predicted stable phases and H2 release reactions are consistent with experimental observations. This demonstrates that our approach rapidly computes the thermochemistry of hydrogen release reactions for compounds at sufficiently high accuracy relative to experiment to provide a powerful framework for analyzing hydrogen storage materials. This framework based on G(T) enables the accelerated discovery of active materials for a variety of technologies that rely on solid-state reactions involving these materials.  © 2020 American Chemical Society.","However, fully mapping the stabilities of known or newly targeted compounds relative to competing phases at reaction conditions has previously required many stringent experiments or computationally demanding calculations of each compound's change in Gibbs energy with respect to temperature, G(T). This demonstrates that our approach rapidly computes the thermochemistry of hydrogen release reactions for compounds at sufficiently high accuracy relative to experiment to provide a powerful framework for analyzing hydrogen storage materials.",_
!191,"Accumulatively roll bonded (ARB) Mg-LaNi5-Soot hybrid has emerged as a promising hydrogen storage material with enhanced hydrogen storage characteristics, which is amenable to scaled-up production. The key to understanding the hydrogen storage behaviour lies in the nanoscale structure of the hybrid and the associated mechanisms. The focus of the current study is on the use of cross-sectional transmission electron microscopy (TEM) to unravel the underlying mechanisms of hydrogen storage, in the Mg-LaNi5-Soot hybrid. The role of processing variables (ARB passes and strain) and the concomitant evolution of the microstructure (distribution of second phase particles (LaNi5 and soot)) are studied, keeping in view the diffusion of hydrogen and the nucleation of the hydride phase. It is established that the interface between Mg and second phase (LaNi5 and soot) plays a dominant role in the nucleation of the MgH2 phase. The MgH2 nucleation mechanism is studied under the ambit of the Johnson-Mehl-Avrami kinetic (JMAK) model. It is concluded that the internal interfaces provides sites for the nucleation of magnesium hydride. © 2020 Hydrogen Energy Publications LLC","Accumulatively roll bonded (ARB) Mg-LaNi5-Soot hybrid has emerged as a promising hydrogen storage material with enhanced hydrogen storage characteristics, which is amenable to scaled-up production. It is concluded that the internal interfaces provides sites for the nucleation of magnesium hydride.",_
!192,"Hydrogen fuel is becoming a hot topic among the scientific community as an alternative energy source. Hydrogen is eco-friendly, renewable, and green. The synthesis and development of materials with great potential for hydrogen storage is still a challenge in research and needs to be addressed to store hydrogen economically and efficiently. Various solid-state materials have been fabricated for hydrogen energy storage; however, carbon-based nanocomposites have gained more attention because of its high surface area, low processing cost, and light weight nature. Carbon materials are easy to modify with various metals, metal oxides (MOs), and other organometallic frameworks because of the functional groups available on the surface and edges that increase the storage capacity of hydrogen. In addition, chemisorption is another way to enhance the hydrogen storage capacity of carbon-based nanocomposites. In this review, we discuss the success achieved thus far and the challenges that remain for the physical and chemical storage of hydrogen in various carbon-based nanocomposites. Various compositions of catalysts (eg, metal, MOs, alloy, metal organic frameworks) and carbon materials are designed for hydrogen storage. Superior energy storage in hybrids and composites as compared with pristine materials (catalysts or carbon nanotubes) is governed by the interaction, activation, and hydrogen adsorption/absorption mechanism of materials in the reaction profile. (Nano)composites comprising carbon material with metals, MOs, or alloys are important in this field, not only because of their potential for hydrogen sorption but also their significant cyclic stability and high efficiency upon successive adsorption-desorption cycles. © 2020 John Wiley & Sons Ltd","Hydrogen fuel is becoming a hot topic among the scientific community as an alternative energy source. In addition, chemisorption is another way to enhance the hydrogen storage capacity of carbon-based nanocomposites.",_
!193,"The development of high-efficiency carbon-based multifunctional catalysts is of great significance for improving solid-state hydrogen storage materials. Herein, it was confirmed that CoMoO4 sheet-like nanocatalysts uniformly supported on the surface of reduced graphene oxide (CoMoO4/rGO) were successfully prepared by a simple hydrothermal reaction. The novel CoMoO4/rGO catalyst was subsequently doped into MgH2 to improve its hydrogen storage performance. MgH2–10 wt% CoMoO4/rGO starts to release hydrogen at around 204 °C, which is about 36 °C and 156 °C lower than that of MgH2 −10 wt%CoMoO4 and pure MgH2, respectively. In addition, 6.25 wt% H2 can be released within 10 min at 300 °C. After complete dehydrogenation, H2 can be absorbed below 80 °C. Meanwhile, it can absorb 4.2 wt% H2 in 20 min under the condition of 150 °C and 3 MPa. Moreover, the activation energy of hydrogen absorption and dehydrogenation of MgH2–10 wt%CoMoO4/rGO composites are reduced by 31.44 kJ mol−1 and 33.78 kJ mol−1, respectively, compared with pure MgH2. Cycling experiment shows that the MgH2–10 wt%CoMoO4/rGO composite system can still maintain about 98% of the hydrogen storage capacity after 10 cycles. Furthermore, studies on the catalytic mechanism show that the synergistic effect between the in-situ generated MgO, Co7Mo6 and Mo may help to promote the diffusion of H2, thereby improving the MgH2 Hydrogen storage properties. © 2022 Elsevier B.V.","Herein, it was confirmed that CoMoO4 sheet-like nanocatalysts uniformly supported on the surface of reduced graphene oxide (CoMoO4/rGO) were successfully prepared by a simple hydrothermal reaction. The novel CoMoO4/rGO catalyst was subsequently doped into MgH2 to improve its hydrogen storage performance.",_
!194,"Magnesium borohydride (Mg(BH4)2) is an attractive compound for solid-state hydrogen storage due to its lucratively high hydrogen densities and theoretically low operational temperature. Hydrogen release from Mg(BH4)2 occurs through several steps. The reaction intermediates formed at these steps have been extensively studied for a decade. In this work, we apply spectroscopic methods that have rarely been used in such studies to provide alternative insights into the nature of the reaction intermediates. The commercially obtained sample was decomposed in argon flow during thermogravimetric analysis combined with differential scanning calorimetry (TGA-DSC) to differentiate between the H2-desorption reaction steps. The reaction products were analyzed by powder X-ray diffraction (PXRD), near edge soft X-ray absorption spectroscopy at boron K-edge (NEXAFS), and synchrotron infrared (IR) spectroscopy in mid- and far-IR ranges (SR-FTIR). Up to 12 wt% of H2 desorption was observed in the gravimetric measurements. PXRD showed no crystalline decomposition products when heated at 260–280 °C, the formation of MgH2 above 300 °C, and Mg above 320 °C. The qualitative analysis of the NEXAFS data showed the presence of boron in lower oxidation states than in (BH4)−. The NEXAFS data also indicated the presence of amorphous boron at and above 340 °C. This study provides additional insights into the decomposition reaction of Mg(BH4)2. © 2022 by the authors.","The reaction intermediates formed at these steps have been extensively studied for a decade. The reaction products were analyzed by powder X-ray diffraction (PXRD), near edge soft X-ray absorption spectroscopy at boron K-edge (NEXAFS), and synchrotron infrared (IR) spectroscopy in mid- and far-IR ranges (SR-FTIR).",_
!195,"A low-cost lumped parameter model (LPM) is developed to simulate hydrogen storage in solid-state materials. The proposed LPM is a zero-dimensional model based on an analogous transient thermal resistance network that considers the whole storage system as a resistor–capacitor (RC) circuit with a current source. Combined with the mass conservation, sorption kinetics, and equation of state, the LPM is capable of predicting key thermofluidic quantities of the storage system, such as the storage bed temperature and pressure, hydrogen fraction and flowrate, and storage tank temperature. To test the applicability of the LPM, chemisorptive (Mg and LaNi5) and physisorptive (activated carbon) solid-state materials are simulated for adsorption and desorption processes. For both material types, LPM achieves predictive accuracies comparable to three-dimensional computational fluid dynamics (CFD) simulations, especially for hydrogen fraction and storage times (with maximum errors less than 9.6%), for a fraction of the computational cost (23,734 times lower memory requirement and 126 times faster calculation time). In addition, several formulations of the bed thermal resistance are proposed and discussed in terms of their impact on the accuracy of the LPM predictions. For slender cylindrical tanks, an equivalent annulus formula achieves the best balance of simplicity and accuracy. © 2021 Elsevier Ltd","A low-cost lumped parameter model (LPM) is developed to simulate hydrogen storage in solid-state materials. For slender cylindrical tanks, an equivalent annulus formula achieves the best balance of simplicity and accuracy.",_
!196,"Effective hydrogen storage capacity is a key factor for applications of solid-state hydrogen storage technology. In this work, V-based solid solution alloys were prepared and the effect of codoping Cr and the rare-earth Y element on the crystal microstructure and reversible hydrogen storage properties were investigated. The results revealed that the hydrogen absorption of Ti-V-Mn-Cr-Y alloys could exceed 90% of the maximum hydrogen capacity within 50 s at 6 MPa hydrogen pressure, and the alloy Ti0.9Y0.1V1.1Mn0.8Cr0.1can absorb maximum 3.71 wt % hydrogen capacity, and the effective hydrogen capacity above 0.1 MPa can reach 2.53 wt % at 423 K. Furthermore, the dehydriding thermodynamic parameters revealed a significant tendency toward easier dehydrogenation with codoping of trans-metal and rare-earth metal elements. © 2022 American Chemical Society. All rights reserved.","In this work, V-based solid solution alloys were prepared and the effect of codoping Cr and the rare-earth Y element on the crystal microstructure and reversible hydrogen storage properties were investigated. The results revealed that the hydrogen absorption of Ti-V-Mn-Cr-Y alloys could exceed 90% of the maximum hydrogen capacity within 50 s at 6 MPa hydrogen pressure, and the alloy Ti0.9Y0.1V1.1Mn0.8Cr0.1can absorb maximum 3.71 wt % hydrogen capacity, and the effective hydrogen capacity above 0.1 MPa can reach 2.53 wt % at 423 K. Furthermore, the dehydriding thermodynamic parameters revealed a significant tendency toward easier dehydrogenation with codoping of trans-metal and rare-earth metal elements.",_
!197,"Following the E-MRS (European Materials Research Society) fall meeting 2019, Symposium L, this Special Issue of Inorganics, entitled “Beyond Hydrogen Storage—Metal Hydrides as Multifunctional Materials for Energy Storage and Conversion”, is dedicated to the wide range of emerging energy-related inorganic hydrogen-containing materials. We have collected six publications with more than 130 journal pages, which clearly document the flourishing future metal hydride-based materials due to their excellent physical and chemical properties. The guest editors hope that you will enjoy and learn from the breadth of science presented in this open-access Special Issue where fundamental scientific concepts are explored beyond the classical hydrogen storage applications of metal hydrides. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.","Following the E-MRS (European Materials Research Society) fall meeting 2019, Symposium L, this Special Issue of Inorganics, entitled “Beyond Hydrogen Storage—Metal Hydrides as Multifunctional Materials for Energy Storage and Conversion”, is dedicated to the wide range of emerging energy-related inorganic hydrogen-containing materials. We have collected six publications with more than 130 journal pages, which clearly document the flourishing future metal hydride-based materials due to their excellent physical and chemical properties.",_
!198,"Mg(BH4)2 is a promising solid-state hydrogen storage material, releasing 14.9 wt% hydrogen upon conversion to MgB2. The rehydrogenation of MgB2 is particularly challenging, requiring prolonged exposure to high pressures of hydrogen at high temperature. Here we report an XPS study probing the influence of LiH and TiH2 on the hydrogen storage properties of MgB2 in the surface and near-surface regions, as a complementary investigation to a preceding study of the bulk properties. Surface and near-surface properties are important considerations for nanoscale and bulk hydrogen storage materials. If there are reactions occurring at the surface that modify the chemical composition in the near-surface region, species diffusion can alter the chemical composition even deep into the bulk of the material. For LiH/MgB2, metastable LiH–B and LiH–Mg species are produced that are more reactive than Bulk MgB2. With prolonged glovebox storage, the LiH/MgB2 material shows increased reactivity towards O and C and enriched levels of Li and B in the near-surface region. In addition, Li induces the growth of Li2CO3 in the surface and near surface regions. Exposing LiH/MgB2 to hydrogen at 700 bar and 280 °C for 24 h produces borohydride at a temperature 100 °C below the threshold for bulk MgB2 hydrogenation. In a specifically surface process with macroscopic implications, the hydrogenation conditions also cause Li2CO3 to react with boron hydroxide in the sample to form a Li-deficient glassy lithium borate melt at the interfaces of the particles, bonding them together. Subsequent heating to 380 °C dehydrogenates the borohydride and eliminates the Li-deficient glassy lithium borate. The LiH/MgB2 material is not reversible because desorption does not lead back to LiH/MgB2, but rather to elemental B and Mg metal in the near-surface region. In contrast to LiH, TiH2 does not react with MgB2, despite the favorable thermodynamics for destabilization via TiB2 formation. Furthermore, high pressure hydrogenation yields only unreacted TiH2 and MgB2 in the surface and near-surface regions. Thus, added TiH2 provides no benefit to MgB2 hydrogenation, in agreement with the findings of the preceding bulk study. © 2021 Hydrogen Energy Publications LLC","The LiH/MgB2 material is not reversible because desorption does not lead back to LiH/MgB2, but rather to elemental B and Mg metal in the near-surface region. In contrast to LiH, TiH2 does not react with MgB2, despite the favorable thermodynamics for destabilization via TiB2 formation.",_
!199,"First-principles density functional theory (DFT) calculations were performed to investigate the effect of ternary alloying on the hydrogenation properties of the TiFe system. Al, Be, Co, Cr, Cu, Mn and Ni were selected as substitutional elements for Fe sites, in the light of their reported enhancement of activation, kinetic and thermodynamic properties. The use of special quasi-random structures to account for disordering of solute elements in the sub-lattice allowed a quantitative assessment of substitutional effects on the hydrogenation behaviour of single-phase TiFe1-xMx alloys, up to a solute concentration as high as 40 at.%. The energy of monohydride formation obtained by DFT calculations, approximated to the enthalpy of formation, was discussed in terms of changes in lattice parameter and hence plateau pressure. Based on the consistency between DFT calculations and earlier experimental results, a linear relationship between monohydride formation energy/enthalpy and plateau pressure was proposed as a simple method to predict the value of one of these physical properties from the other. The obtained correlation could therefore turn out to be a helpful tool to predict the ab/desorption plateau pressure of unexplored vast multi-component systems from DFT calculation, or, the other way around, could allow to estimate the formation enthalpy from only one pressure-composition-isotherm (PCI) measurement hence without the need of Van't Hoff plot. © 2022 The Author(s)","Al, Be, Co, Cr, Cu, Mn and Ni were selected as substitutional elements for Fe sites, in the light of their reported enhancement of activation, kinetic and thermodynamic properties. Based on the consistency between DFT calculations and earlier experimental results, a linear relationship between monohydride formation energy/enthalpy and plateau pressure was proposed as a simple method to predict the value of one of these physical properties from the other.",_
!200,"Reversible solid-state hydrogen storage in metal hydrides is a key technology for pollution-free energy conversion systems. Herein, the LiBH2–MgH2 composite system with and without ScCl3 additive is investigated using synchrotron- and neutron-radiation-based probing methods that can be applied to characterize such lightweight metal–hydrogen systems from nanoscopic levels up to macroscopic scale. Combining the results of neutron- and photon-based methods allows a complementary insight into reaction paths and mechanisms, complex interactions between the hydride matrix and additive, hydrogen distribution, material transport, structural changes, and phase separation in the hydride matrix. The gained knowledge is of great importance for development and optimization of such novel metal-hydride-based hydrogen storage systems with respect to future applications. © 2021 The Authors. Advanced Engineering Materials published by Wiley-VCH GmbH.","Reversible solid-state hydrogen storage in metal hydrides is a key technology for pollution-free energy conversion systems. Herein, the LiBH2–MgH2 composite system with and without ScCl3 additive is investigated using synchrotron- and neutron-radiation-based probing methods that can be applied to characterize such lightweight metal–hydrogen systems from nanoscopic levels up to macroscopic scale.",_
!201,"Fast forging of compacts made up of Mg and Ni powders is shown to be an effective method to induce severe plastic deformation with improved H2 sorption properties. Here, using such processed samples, a comprehensive analysis of the sorption properties reveals that the first hydrogenation sequence significantly depends on the forging temperature, through different microstructures. More in detail, no phase transformation occurs upon cold forging, while solid-state reaction leads to the formation of the Mg2Ni intermetallic compound upon forging above 400 °C. Forging below the brittle-to-ductile transition (225-250 °C) leads to faster H2 uptake upon first absorption owing to a more textured fiber along the c-axis and internal strains which promote hydrogen diffusion through the bulk material. Desorption kinetics remain slower with low-temperature forging, despite Ni recombining to form Mg2Ni during the first desorption. After several cycles, a two-step behavior is observed with a fast absorption step occurring up to about 3 wt.%. Despite this limited uptake performance, the forging process can be considered as a straightforward, safe, and cost-efficient process to produce large amounts of Mg-based alloys for hydrogen storage. In particular, such severe plastic deformation processes can be considered as reliable substitutes for ball-milling, which is highly efficient but energy- and time-consuming.  © 2020 by the authors.","Despite this limited uptake performance, the forging process can be considered as a straightforward, safe, and cost-efficient process to produce large amounts of Mg-based alloys for hydrogen storage. In particular, such severe plastic deformation processes can be considered as reliable substitutes for ball-milling, which is highly efficient but energy- and time-consuming.",_
!202,"The impact of boron doping on MgH2 bonding mechanism, hydrogen diffusion and desorption was calculated using density functional theory (DFT). Atomic interactions in doped and non-doped system and its influence on hydrogen and vacancy diffusion were studied in bulk hydride. Slab calculations were performed to study hydrogen desorption energies from (110) boron doped surface and its dependence on the surface configuration and depth position. To study kinetics of hydrogen diffusion in boron vicinity and hydrogen molecule desorption activation energies from boron doped and non-doped (110) MgH2 surface Nudged Elastic Band (NEB) method was used. Results showed that boron forms stronger, covalent bonds with hydrogen causing the destabilization in its first and second coordination. This leads to lower hydrogen desorption energies and improved hydrogen diffusion, while the impact on the energy barriers for H2 desorption from hydride (110) surface is less pronounced. © 2019 Hydrogen Energy Publications LLC","The impact of boron doping on MgH2 bonding mechanism, hydrogen diffusion and desorption was calculated using density functional theory (DFT). Results showed that boron forms stronger, covalent bonds with hydrogen causing the destabilization in its first and second coordination.",_
!203,"β Ti–Nb BCC alloys are potential materials for hydrogen storage in the solid state. Since these alloys present exceptional formability, they can be processed by extensive cold rolling (ECR), which can improve hydrogen sorption properties. This work investigated the effects of ECR accomplished under an inert atmosphere on H2 sorption properties of the arc melted and rapidly solidified β Ti40Nb alloy. Samples were crushed in a rolling mill producing slightly deformed pieces within the millimeter range size, which were processed by ECR with 40 or 80 passes. Part of undeformed fragments was used for comparison purposes. All samples were characterized by scanning electron microscopy, x-ray diffractometry, energy-dispersive spectroscopy, hydrogen volumetry, and differential scanning calorimetry. After ECR, samples deformed with 40 passes were formed by thick sheets, while several thin layers composed the specimens after 80 passages. Furthermore, deformation of β Ti–40Nb alloys synthesized samples containing a high density of crystalline defects, cracks, and stored strain energy that increased with the deformation amount and proportionally helped to overcome the diffusion's control mechanisms, thus improving kinetic behaviors at low temperature. Such an improvement was also correlated to the synergetic effect of resulting features after deformation and thickness of stacked layers in the different deformation conditions. At the room temperature, samples deformed with 80 passes absorbed ∼2.0 wt% of H2 after 15 min, while samples deformed with 40 passes absorbed ∼1.8 wt% during 2 h, excellent results if compared with undeformed samples hydrogenated at 300 °C that acquired a capacity of ∼1.7 wt% after 2 h. The hydrogen desorption evolved in the same way as for absorption regarding the deformation amount, which also influenced desorption temperatures that were reduced from ∼270 °C, observed for the undeformed and samples deformed with 40 passes, to ∼220 °C, for specimens rolled with 80 passes. No significant loss in hydrogen capacity was observed in the cold rolled samples. © 2019 Hydrogen Energy Publications LLC","β Ti–Nb BCC alloys are potential materials for hydrogen storage in the solid state. Furthermore, deformation of β Ti–40Nb alloys synthesized samples containing a high density of crystalline defects, cracks, and stored strain energy that increased with the deformation amount and proportionally helped to overcome the diffusion's control mechanisms, thus improving kinetic behaviors at low temperature.",_
!204,"Cluster-based materials are candidate materials for solid-state hydrogen storage owing to their special geometric and electronic structures. The surface adsorption and the encapsulated storage of H2 molecules in a cagelike (MgO)12 cluster have been studied using density functional theory (DFT) calculations including a dispersion interaction. The results revealed that the cagelike (MgO)12 cluster surface can adsorb 24 H2 molecules with an average adsorption energy of 0.116 eV/H2, which brings about a gravimetric density of 9.1 wt%. Compared with dispersion-corrected DFT calculations, the traditional DFT method substantially underestimates the surface adsorption strength. According to symmetric configurations, a maximum capacity of six H2 molecules can be stored in the interior space of the cagelike (MgO)12 cluster. The encapsulated H2 molecules are trapped by stepwise energy barriers of 0.433–2.550 eV, although the storage is an endothermic process. The present study will be beneficial for hydrogen storage in cagelike clusters and assembled porous materials. © 2018 Hydrogen Energy Publications LLC",The surface adsorption and the encapsulated storage of H2 molecules in a cagelike (MgO)12 cluster have been studied using density functional theory (DFT) calculations including a dispersion interaction. The present study will be beneficial for hydrogen storage in cagelike clusters and assembled porous materials.,_
!205,"Hydrogen is considered as a propitious and sound alternative to fossil fuels. The current technologies allow hydrogen to be stored in the forms of gas, liquid, and solid. The solid-state hydrogen storage offers higher energy capacity with advantageous safety considerations. This chapter presents the current materials and technologies for hydrogen storage, which emphasized the solid-state form. These include various types of solid-state materials based on physisorption and chemisorption. In this chapter, different categories of materials such as binary hydrides, complex hydrides, and nanoconfinement are reviewed and discussed. Besides, hydrogen storage in the forms of compressed gas and liquid is presented in this chapter. © 2020 Elsevier Inc. All rights reserved.",Hydrogen is considered as a propitious and sound alternative to fossil fuels. These include various types of solid-state materials based on physisorption and chemisorption.,_
!206,"Intermetallic TiMn2 compound was employed for improving the de/rehydrogenation kinetics behaviors of MgH2 powders. The metal hydride powders, obtained after 200 h of reactive ball milling was doped with 10 wt% TiMn2 powders and high-energy ball milled under pressurized hydrogen of 70 bar for 50 h. The cold-pressing technique was used to consolidate them into 36-green buttons with 12 mm in diameter. During consolidation, the hard TiMn2 spherical powders deeply embedded into MgH2 matrix to form homogeneous nanocomposite bulk material. The apparent activation energies of hydrogenation and dehydrogenation for the fabricated buttons were 19.3 kJ/mol and 82.9 kJ/mol, respectively. The present MgH2/10 wt% TiMn2 nanocomposite binary system possessed superior hydrogenation/dehydrogenation kinetics at 225 °C to absorb/desorb 5.1 wt% hydrogen at 10 bar/200 mbar H2 within 100 s and 400 s, respectively. This new system revealed good cyclability of achieving 414 cycles within 600 h continuously without degradations. For the present study, the consolidated buttons were used as solid-state hydrogen storage for feeding proton-exchange membrane fuel cell through a house made Ti-reactor at 250 °C. This nanocomposite system possessed good capability for providing the fuel cell with hydrogen flow at an average rate of 150 ml/min. The average current and voltage outputs were 3 A and 5.5 V, respectively. © 2019 Hydrogen Energy Publications LLC","The metal hydride powders, obtained after 200 h of reactive ball milling was doped with 10 wt% TiMn2 powders and high-energy ball milled under pressurized hydrogen of 70 bar for 50 h. The cold-pressing technique was used to consolidate them into 36-green buttons with 12 mm in diameter. This nanocomposite system possessed good capability for providing the fuel cell with hydrogen flow at an average rate of 150 ml/min.",_
!207,"Recently, transition metal oxides have been evidenced to be superior catalysts for improving the hydrogen desorption/absorption performance of MgH2. In this paper, Mn3O4 nanoparticles with a uniform size of around 10 nm were synthesized by a facile chemical method and then introduced to modify the hydrogen storage properties of MgH2. With the addition of 10 wt% Mn3O4 nanoparticles, the MgH2-Mn3O4 composite started to release hydrogen at 200 °C and approximately 6.8 wt% H2 could be released within 8 min at 300 °C. For absorption, the completely dehydrogenated sample took up 5.0 wt% H2 within 10 min under 3 MPa hydrogen even at 100 °C. Compared with pristine MgH2, the activation energy value of absorption for the MgH2 + 10 wt% Mn3O4 composite decreased from 72.5 ± 2.7 to 34.4 ± 0.9 kJ mol-1. The catalytic mechanism of Mn3O4 was also explored and discussed with solid evidence from X-ray diffraction (XRD), Transmission Electron Microscope (TEM) and Energy Dispersive X-ray Spectroscopy (EDS) studies. Density functional theory calculations revealed that the Mg-H bonds were elongated and weakened with the doping of Mn3O4. In addition, a cycling test showed that the hydrogen storage capacity and reaction kinetics of MgH2-Mn3O4 could be favourably preserved in 20 cycles, indicative of promising applications as a solid-state hydrogen storage material in a future hydrogen society. This journal is © The Royal Society of Chemistry.","Recently, transition metal oxides have been evidenced to be superior catalysts for improving the hydrogen desorption/absorption performance of MgH2. For absorption, the completely dehydrogenated sample took up 5.0 wt% H2 within 10 min under 3 MPa hydrogen even at 100 °C.",_
!208,"Due to its affordable price, abundance, high storage capacity, low recycling coast, and easy processing, Mg metal is considered as a promising hydrogen storage material. However, the poor de/rehydrogenation kinetics and strong stability of MgH2 must be improved before proposing this material for applications. Doping MgH2 powders with one or more catalytic agents is one common approach leading to obvious improving on the behavior of MgH2. The present study was undertaken to investigate the effect of doping MgH2 with 7 wt% of amorphous(a)-LaNi3 nanopowders on hydrogenation/dehydrogenation behavior of the metal hydride powders. The results have shown that rod milling MgH2 with a-LaNi3 abrasive nanopowders led to disintegrate microscale-MgH2 powders to nanolevel. The final nanocomposite product obtained after 50 h–100 h of rod milling revealed superior hydrogenation kinetics, indexed by short time (8 min) required to absorb 6 wt% of H2 at 200◦C/10 bar. At 225◦C/200 mbar, nanocomposite powders revealed outstanding dehydrogenation kinetics, characterized by very short time (2 min) needed to release 6 wt% of H2. This new tailored solid-hydrogen storage system experienced long cycle-life-time (2000 h) at 225◦C without obeying to sever degradation on its kinetics and/or storage capacity. © 2019 by the authors.","However, the poor de/rehydrogenation kinetics and strong stability of MgH2 must be improved before proposing this material for applications. At 225◦C/200 mbar, nanocomposite powders revealed outstanding dehydrogenation kinetics, characterized by very short time (2 min) needed to release 6 wt% of H2.",_
!209,"Lithium alanate (LiAlH4) is of particular interest as one of the most promising candidates for solid-state hydrogen storage. Unfortunately, high dehydrogenation temperatures and relatively slow kinetics limit its practical applications. Herein, 3D flower-like nanocrystalline Ni/C, composed of highly dispersed Ni nanoparticles and interlaced carbon flakes, was synthesized in situ. The as-synthesized nanocrystalline Ni/C significantly decreased the dehydrogenation temperature and dramatically improved the dehydrogenation kinetics of LiAlH4. It was found that the LiAlH4 sample with 10 wt % Ni/C (LiAlH4-10 wt %Ni/C) began hydrogen desorption at approximately 48 °C, which is very close to ambient temperature. Approximately 6.3 wt % H2 was released from LiAlH4-10 wt %Ni/C within 60 min at 140 °C, whereas pristine LiAlH4 only released 0.52 wt % H2 under identical conditions. More importantly, the dehydrogenated products can partially rehydrogenate at 300 °C under 4 MPa H2. The synergetic effect of the flower-like carbon substrate and Ni active species contributes to the significantly reduced dehydrogenation temperatures and improved kinetics. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim","Unfortunately, high dehydrogenation temperatures and relatively slow kinetics limit its practical applications. Herein, 3D flower-like nanocrystalline Ni/C, composed of highly dispersed Ni nanoparticles and interlaced carbon flakes, was synthesized in situ.",_
!210,"Hydrogen energy is a highly efficient and renewable energy carrier. The rapid and sophisticated development of nanotechnologies has promoted the transition of hydrogen storage systems from gaseous/liquid to solid-state. In order to clarify the intrinsic relationship between structure and performance, and to understand the hydrogen absorption and desorption mechanism of materials, electron microscopy (EM) can effectively help us obtain a series of information such as particle size, phase and composition determination, morphology and structure of the materials at nanoscale. The most recent progress of advanced EM techniques applied in solid-state hydrogen storage materials are summarized, which should also inspire future research on energy storage related materials. © 2020 Hydrogen Energy Publications LLC","The rapid and sophisticated development of nanotechnologies has promoted the transition of hydrogen storage systems from gaseous/liquid to solid-state. The most recent progress of advanced EM techniques applied in solid-state hydrogen storage materials are summarized, which should also inspire future research on energy storage related materials.",_
!211,"Magnesium hydride and selected magnesium-based ternary hydride (Mg2FeH6, Mg2NiH4, and Mg2CoH5) syntheses and modification methods, as well as the properties of the obtained materials, which are modified mostly by mechanical synthesis or milling, are reviewed in this work. The roles of selected additives (oxides, halides, and intermetallics), nanostructurization, polymorphic transformations, and cyclic stability are described. Despite the many years of investigations related to these hydrides and the significant number of different additives used, there are still many unknown factors that affect their hydrogen storage properties, reaction yield, and stability. The described compounds seem to be extremely interesting from a theoretical point of view. However, their practical application still remains debatable. © 2020 by the authors.","Despite the many years of investigations related to these hydrides and the significant number of different additives used, there are still many unknown factors that affect their hydrogen storage properties, reaction yield, and stability. The described compounds seem to be extremely interesting from a theoretical point of view.",_
!212,"We have investigated the structure and hydrogen storage properties of a series of quaternary and quintary high-entropy alloys related to the ternary system TiVNb with powder X-ray diffraction (PXD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and manometric measurements in a Sieverts apparatus. The alloys have body-centred cubic (bcc) crystal structures and form face-centred cubic (fcc) metal hydrides with hydrogen-to-metal ratios close to 2 by hydrogenation. The onset temperature for hydrogen desorption, Tonset, decreases linearly with the valence-electron concentration, VEC. Moreover, the volumetric expansion per metal atom from the bcc alloys to the fcc hydrides, [(V/Z)fcc−(V/Z)bcc]/(V/Z)bcc, increases linearly with the VEC. Therefore, it seems that a larger expansion of the lattice destabilizes the metal hydrides and that this effect can be tuned by altering the VEC. Kissinger analyses performed on the DSC measurements indicate that the destabilization is a thermodynamic rather than kinetic effect. Based upon these insights we have identified TiVCrNbH8 as a material with suitable thermodynamics for hydrogen storage in the solid state. This HEA-based hydride has a reversible hydrogen storage capacity of 1.96 wt% H at room temperature and moderate H2-pressures. Moreover, it is not dependent on any elaborate activation procedure to absorb hydrogen. © 2019 Acta Materialia Inc.",Based upon these insights we have identified TiVCrNbH8 as a material with suitable thermodynamics for hydrogen storage in the solid state. This HEA-based hydride has a reversible hydrogen storage capacity of 1.96 wt% H at room temperature and moderate H2-pressures.,_
!213,"Polygeneration Microgrids (PMG) are smart energy systems which can be configured for decentralised multiple outputs in the form of electricity, heat, cold, fuel (hydrogen) and drinking water. This paper presents an analysis of a stand-alone PMG, which caters to electrical, thermal and hydrogen loads. The stand-alone PMG consisting of solar photovoltaic field, fuel cell, solid state hydrogen storage and electrolyzer is modelled using commercial software HOMER. An hourly simulation is conducted to analyse its annual performance. A case study is carried out for a typical Indian village of about 50 households needing electrical energy of 100 kWh/day. The by-products of the optimized stand-alone PMG i.e., thermal energy and hydrogen, are quantified. © 2020 Elsevier Ltd","Polygeneration Microgrids (PMG) are smart energy systems which can be configured for decentralised multiple outputs in the form of electricity, heat, cold, fuel (hydrogen) and drinking water. The stand-alone PMG consisting of solar photovoltaic field, fuel cell, solid state hydrogen storage and electrolyzer is modelled using commercial software HOMER.",_
!214,"The rapid and extensive development of advanced nanostructures and nanotechnologies has driven a correspondingly rapid growth of research that presents enormous potential for fulfilling the practical requirements of solid state hydrogen storage applications. This article reviews the most recent progress in the development of nanostructured materials for hydrogen storage technology, demonstrating that nanostructures provide a pronounced benefit to applications involving molecular hydrogen storage, chemical hydrogen storage, and as supports for the nanoconfinement of various hydrides. To further optimize hydrogen storage performance, we emphasize the desirability of exploring and developing nanoporous materials with ultrahigh surface areas and the advantageous incorporation of metals and functionalities, nanostructured hydrides with excellent mechanic stabilities and rigid main construction, and nanostructured supports comprised of lightweight components and enhanced hydride loading capacities. In addition to highlighting the conspicuous advantages of nanostructured materials in the field of hydrogen storage, we also discuss the remaining challenges and the directions of emerging research for these materials. © 2017 Elsevier Ltd","The rapid and extensive development of advanced nanostructures and nanotechnologies has driven a correspondingly rapid growth of research that presents enormous potential for fulfilling the practical requirements of solid state hydrogen storage applications. This article reviews the most recent progress in the development of nanostructured materials for hydrogen storage technology, demonstrating that nanostructures provide a pronounced benefit to applications involving molecular hydrogen storage, chemical hydrogen storage, and as supports for the nanoconfinement of various hydrides.",_
!215,"This review summarizes the results of the studies of structural and absorption characteristics of thin-film (V, Ti)Nx-Hy hydrogen storage devices that have been conducted at the National Science Center ""Kharkov Institute of Physics and Technology"" in the last 10 years. It sets out analyzing the basic principles for producing the porous nano-crystalline thin films using the Ion-Beam Assisted Deposition (IBAD) technique. The detailed analysis of electron microscopic investigation of the film structure at all growth stages (from 5 nm to 1 μm) is provided. It is shown how the bombardment with gas ions during the film deposition contributes to a formation of intergranular nanopores. The size of nanopores and their distribution were determined by means of neutron spectroscopy analysis. Using the nuclear-physical methods, the total volume of intergranular pores was measured and it was shown that, depending on the parameters of the IBAD process, the porosity can vary from 10 to 27 vol. %. It was noted that nuclear physics methods are also relevant for determining the hydrogen amount absorbed by thin films. The review contains the results of research regarding the influence of the film thickness, the presence of a protective nickel coating, and the hydrogen saturation technique on the gravimetric capacity of the films. Investigated nanoporous (V, Ti)Nx-Hy thin films can absorb up to 8 wt. % of hydrogen, and hydrogen release occurs in the temperature range from 50 to 350°C. Based on the results of the studies, it is substantiated why the transition from simple vanadium and titanium hydrides to complex ones leads to a significant improvement both of their gravimetric capacity and thermodynamic and kinetic characteristics. © 2018 by Nova Science Publishers, Inc. All rights reserved.","It was noted that nuclear physics methods are also relevant for determining the hydrogen amount absorbed by thin films. Investigated nanoporous (V, Ti)Nx-Hy thin films can absorb up to 8 wt.",_
!216,"In the present study, a cylindrical solid state hydrogen storage device embedded with finned heat exchanger is numerically investigated. The finned heat exchanger consists of two ‘U’ shaped tube and circular fins brazed on the periphery of the tubes. 1 kg of LaNi5 alloy is filled inside the device and 80 g of copper flakes is evenly distributed in between the fins to increase the overall thermal conductivity of the metal hydride. Water is used as heat transfer fluid. Absorption performance of the storage device is investigated at constant hydrogen supply pressure of 15 bar and cooling fluid temperature and velocity of 298 K and 1 m/s respectively. At these operating conditions, the required charging time is found to be around 610 s for a storage capacity of 12 g (1.2 wt%). The study is extended to examine the influence of different heat exchanger configurations based on number of fins, thickness of the fins, diameter of tubes, holes in fins, amount of copper flakes etc. An analysis for the same weight of the heat exchanger assembly has also been carried out by changing the number of fins at different thickness and pitch. © 2017 Hydrogen Energy Publications LLC","In the present study, a cylindrical solid state hydrogen storage device embedded with finned heat exchanger is numerically investigated. At these operating conditions, the required charging time is found to be around 610 s for a storage capacity of 12 g (1.2 wt%).",_
!217,"With advantages of high hydrogen capacity, excellent reversibility, and low cost, magnesium hydride (MgH2) has been considered as one of the most promising candidates for solid-state hydrogen storage. However, the practical use of MgH2 as a hydrogen storage medium still needs to overcome great barriers both in the thermodynamics and kinetics. In this respect, nanotechnology plays an important role. Employing appropriate nanocatalysts for the hydrogen sorption and/or reducing the particle size of MgH2 to nanoscale have been demonstrated to be effective strategies. In this review, we present a detailed survey on the recent advances in nanocatalysts and nanostructuring for high-performance MgH2. First, we introduce various categories of nanocatalysts, especially including metals and their compounds, focusing on their effects on hydrogen sorption performance of MgH2. Then nanostructuring methods for the preparation of small-sized freestanding Mg/MgH2 are discussed, and typical works in nanoconfinement of MgH2 are revisited as a nanostructuring methodology. Finally, we analyze the remaining issues and challenges and propose the prospects of research and development in MgH2 as hydrogen storage materials in the future. © 2019 Elsevier Ltd","With advantages of high hydrogen capacity, excellent reversibility, and low cost, magnesium hydride (MgH2) has been considered as one of the most promising candidates for solid-state hydrogen storage. Then nanostructuring methods for the preparation of small-sized freestanding Mg/MgH2 are discussed, and typical works in nanoconfinement of MgH2 are revisited as a nanostructuring methodology.",_
!218,"Solid-state hydrogen storage materials undergo complex phase transformations in which kinetics are often limited by hydrogen diffusion that significantly changes during hydrogen uptake and release. Here we perform robust statistically-averaged molecular dynamics simulations to obtain a well-converged analytical expression for hydrogen diffusivity in bulk palladium that is valid throughout all stages of the reaction. Our studies confirm the experimentally observed dependence of the diffusivity on concentration and temperature and elucidate the underlying physics. Whereas at low hydrogen concentrations, a single dilute hopping barrier dominates, at high hydrogen concentrations, diffusion exhibits multiple hopping barriers corresponding to hydrogen-rich and hydrogen-poor local environments. © 2018","Here we perform robust statistically-averaged molecular dynamics simulations to obtain a well-converged analytical expression for hydrogen diffusivity in bulk palladium that is valid throughout all stages of the reaction. Whereas at low hydrogen concentrations, a single dilute hopping barrier dominates, at high hydrogen concentrations, diffusion exhibits multiple hopping barriers corresponding to hydrogen-rich and hydrogen-poor local environments.",_
!219,"The high dehydrogenation temperature of magnesium hydride MgH2 is still the main obstacle to its practical application as a solid-state hydrogen storage medium. Using experimental and first-principles calculations approaches, we, for the first time, investigate the catalytic effect and mechanism of nickel phthalocyanine on the dehydrogenation properties of MgH2. The results display that a small amount of nickel phthalocyanine can promote MgH2 dehydrogenation at significantly decreased temperatures by more than 90 °C relative to milled pristine or graphene-added MgH2 system. However, the agglomeration of MgH2 particles is not evidently alleviated through nickel phthalocyanine addition. When MgH2 is milled with graphene firstly and then the obtained mixture is further milled with nickel phthalocyanine, the dehydrogenation properties and agglomeration of MgH2 particles can be synergistically improved to some extent. The first-principles calculations of dehydrogenation enthalpy and binding energy account for the experimental differences in catalysis and aggregation-resistance abilities of nickel phthalocyanine and graphene on MgH2 particles. Notably, the NiN4-inserted graphene is predicted to be an ideal additive for MgH2, which combines the synergetic catalysis-confinement effect of nickel phthalocyanine and graphene on MgH2 particles. Analysis of electronic structures reveals that the excellent catalytic effect of nickel phthalocyanine on MgH2 can be ascribed to the more electron transfer between nickel phthalocyanine and MgH2, which induces the significantly weakened bond strength of Mg[sbnd]H and decreased dehydrogenation enthalpy of MgH2. © 2017 Hydrogen Energy Publications LLC","The results display that a small amount of nickel phthalocyanine can promote MgH2 dehydrogenation at significantly decreased temperatures by more than 90 °C relative to milled pristine or graphene-added MgH2 system. When MgH2 is milled with graphene firstly and then the obtained mixture is further milled with nickel phthalocyanine, the dehydrogenation properties and agglomeration of MgH2 particles can be synergistically improved to some extent.",_
!220,"High-pressure torsion (HPT) is widely used as a severe plastic deformation technique to create ultrafine-grained structures with promising mechanical and functional properties. Since 2007, the method has been employed to enhance the hydrogenation kinetics in different Mg-based hydrogen storage materials. Recent studies showed that the method is effective not only for increasing the hydrogenation kinetics but also for improving the hydrogenation activity, for enhancing the air resistivity and more importantly for synthesizing new nanostructured hydrogen storage materials with high densities of lattice defects. This manuscript reviews some major findings on the impact of HPT process on the hydrogen storage performance of different titanium-based and magnesium-based materials. © 2018 The Author(s). Published by National Institute for Materials Science in partnership with Taylor & Francis.",High-pressure torsion (HPT) is widely used as a severe plastic deformation technique to create ultrafine-grained structures with promising mechanical and functional properties. Published by National Institute for Materials Science in partnership with Taylor & Francis.,_
!221,"Currently, hydrogen storage research is generally on-board-application oriented. However, the scenario of grid-scale hydrogen energy storage is remarkably different fromon-board application, thus leading to diversity of performance requirements for hydrogen storage. In this paper, technical indicators of solid-state hydrogen storage systems and hydrogen storage materials for grid-scale hydrogen energy storage were studied. Firstly, performance requirements of hydrogen uptake and release for the hydrogen storage system were obtained by analyzing technical characteristics of electrolysis system and fuel cell system. Then, the technical targets of the solid-state hydrogen storage system and hydrogen storage materials for grid-scale application were put forwards, taking into account research and development status of hydrogen storage technology. The technical targets will guide research and development of solid-state hydrogen storage technology and materials for grid-scale applicationin the future. © 2017, Power System Technology Press. All right reserved.","However, the scenario of grid-scale hydrogen energy storage is remarkably different fromon-board application, thus leading to diversity of performance requirements for hydrogen storage. The technical targets will guide research and development of solid-state hydrogen storage technology and materials for grid-scale applicationin the future.",_
!222,"The absorption and desorption performances of a solid state (metal hydride) hydrogen storage device with a finned tube heat exchanger are experimentally investigated. The heat exchanger design consists of two “U” shaped cooling tubes and perforated annular copper fins. Copper flakes are also inserted in between the fins to increase the overall effective thermal conductivity of the metal hydride bed. Experiments are performed on the storage device containing 1 kg of hydriding alloy LaNi5, at various hydrogen supply pressures. Water is used as the heat transfer fluid. The performance of the storage device is investigated for different operating parameters such as hydrogen supply pressure, cooling fluid temperature and heating fluid temperature. The shortest charging time found is 490 s for the absorption capacity of 1.2 wt% at a supply pressure of 15 bar and cooling fluid temperature and velocity of 288 K and 1 m/s respectively. The effect of copper flakes on absorption performance is also investigated and compared with a similar storage device without copper flakes. © 2017 Hydrogen Energy Publications LLC","The heat exchanger design consists of two “U” shaped cooling tubes and perforated annular copper fins. Experiments are performed on the storage device containing 1 kg of hydriding alloy LaNi5, at various hydrogen supply pressures.",_
!223,"Solid-state hydrogen storage in metal hydrides offers highest volumetric energy storage densities and low working gas pressures at the same time. Recently developed metal hydride composites (MHC) consist of a hydride-forming metal alloy and a secondary phase, typically graphite, to realize form-stable composites and short loading and unloading times (<5 min). Hydride formation causes a volume expansion of the storage material. Thus, it is mandatory to characterize this behavior for the sake of system safety. This work focuses on the in-operando characterization of the volume expansion of MHC that could trigger mechanical stresses acting on the walls and internal assemblies of the storage container. MHC with different metal particle shapes (flakes and powder) were studied. In-operando neutron imaging of axially freely expanding MHC was applied to analyze the time-resolved and spatial concentration of hydrogen, reaction fronts and the evolution of volume expansion and stability of the MHC. Stress measurements revealed that stresses of up to 330% of the respective operating gas pressure occur for confined MHC. Both techniques combined deliver crucial information and implications for the design of safe (according to ISO 16111), efficient and dynamic metal hydride storage systems. © 2018 Elsevier B.V.","Thus, it is mandatory to characterize this behavior for the sake of system safety. MHC with different metal particle shapes (flakes and powder) were studied.",_
!224,"Novel nano biomass (NBM) was synthesized using a general and simple synthetic approach. In this process, the walnut shell is used as a green carbon source. According to the transmission electron microscopy and dynamic light scattering results, the average particle size of the produced activated carbon was 2.25 nm. The surface area of the NBM was around 420.5 m2/g totally. High pore volume, high internal surface area, lightweight as well as easy availability are some features that attract research interests on activated carbon as a solid-state hydrogen storage medium. Nano biomass was deposited directly on a copper substrate by the slurry-coating method. The electrochemical properties of nano biomass were investigated in a three-electrode electrolytic cell with 6 M KOH as the electrolyte by galvanostatic charging and discharging. Several parameters such as the impact of the number of charge and discharge cycles and discharge time are studied. Different experimental results show that Cu-NBM has 1596 mAh/g discharge capacity (corresponding to a hydrogen storage capacity of 5.66 wt%) after 16 cycles at room temperature and atmospheric conditions. Due to porosity of NBM particles, the nano biomass showed reversible hydrogen storage capacities that were better than those of previously reported porous carbons. © 2019 Hydrogen Energy Publications LLC",Novel nano biomass (NBM) was synthesized using a general and simple synthetic approach. Nano biomass was deposited directly on a copper substrate by the slurry-coating method.,_
!225,"LiBH4 is of particular interest as one of the most promising materials for solid-state hydrogen storage. Herein, LiBH4 is confined into a novel two-dimensional layered Ti3C2 MXene through a facile impregnation method for the first time to improve its hydrogen storage performance. The initial desorption temperature of LiBH4 is significantly reduced, and the de-/rehydrogenation kinetics are remarkably enhanced. It is found that the initial desorption temperature of LiBH4@2Ti3C2 hybrid decreases to 172.6 °C and releases 9.6 wt % hydrogen at 380 °C within 1 h, whereas pristine LiBH4 only releases 3.2 wt % hydrogen under identical conditions. More importantly, the dehydrogenated products can partially rehydrogenate at 300 °C and under 95 bar H2. The nanoconfined effect caused by unique layered structure of Ti3C2 can hinder the particles growth and agglomeration of LiBH4. Meanwhile, Ti3C2 could possess superior effect to destabilize LiBH4. The synergetic effect of destabilization and nanoconfinement contributes to the remarkably lowered desorption temperature and improved de-/rehydrogenation kinetics. © 2018 American Chemical Society.","It is found that the initial desorption temperature of LiBH4@2Ti3C2 hybrid decreases to 172.6 °C and releases 9.6 wt % hydrogen at 380 °C within 1 h, whereas pristine LiBH4 only releases 3.2 wt % hydrogen under identical conditions. More importantly, the dehydrogenated products can partially rehydrogenate at 300 °C and under 95 bar H2.",_
!226,"Low temperature formation of Mg2FeH6 is demonstrated by hydrogenation of Mg-Fe elemental powder mixture at a temperature as low as 350 °C which is lower than the conventional process temperature, 500 °C. To enable the low temperature synthesis, the powder mixture of Mg and Fe has been prepared by high energy ball milling using different process control agents (PCAs). A systematic study on the ball milling and hydrogenation conditions has been carried out to maximize the yield of the ternary line compound. The hydrogenation conditions together with the particle size of the starting materials turn out to play a significant role in the hydrogenation kinetics of the system. An optimized condition has demonstrated a significant hydrogenation as well as a robust cycling ability at low temperature which suggests the strong potential of the process for practical applications. © 2017 Elsevier Ltd","To enable the low temperature synthesis, the powder mixture of Mg and Fe has been prepared by high energy ball milling using different process control agents (PCAs). An optimized condition has demonstrated a significant hydrogenation as well as a robust cycling ability at low temperature which suggests the strong potential of the process for practical applications.",_
!227,"In this study, the nano-mixture of LiBH4 + MgH2 is prepared by ball milling (BM) of 1 mol MgH2 with in-situ aerosol-spraying (AS) of 1 mol of LiBH4 (called BMAS). It is shown, for the first time, that Mg(BH4)2 can be formed via the reaction between MgH2 and LiBH4 through the BMAS process and it contributes to H2 release at temperature ≤265 °C. Three parallel H2 release mechanisms have been identified from the BMAS powder. These include (i) H2 release from the decomposition of nano-LiBH4 and then Li2B12H12 decomposition product reacts with nano-MgH2 to release H2, (ii) H2 release from the decomposition of nano-Mg(BH4)2, and (iii) H2 release from the decomposition of nano-MgH2. Together, these three mechanisms result in 4.11 wt% H2 release in the solid-state at temperature ≤265 °C, which is among the highest quantities ever reported for LiBH4 + MgH2 mixtures to date. Furthermore, the H2 release temperature for each mechanism described above is lower than the corresponding temperature reported using other synthesis methods. In addition, the predicted property of a small amount of the Fe3B phase in the BMAS powder in absorbing more H2 than releasing is confirmed experimentally for the first time in this study. All these enhancements are achieved in the solid-state without any catalyst, which highlights the efficacy of mechanical activation and nanoengineering as well as the future opportunity to further improve the reversible hydrogen storage properties of LiBH4 + MgH2 in solid-state. © 2019","Three parallel H2 release mechanisms have been identified from the BMAS powder. Together, these three mechanisms result in 4.11 wt% H2 release in the solid-state at temperature ≤265 °C, which is among the highest quantities ever reported for LiBH4 + MgH2 mixtures to date.",_
!228,"As important as the production of CO2-free energy is, so is the motivation to develop efficient storage of renewable energies for mobile and stationary applications. There is no doubt that metal hydrides continue to attract the overall materials science community, and it is not only restrained to a specialized hydrogen field. This is mainly the case when it is the matter of coupled technologies with other systems such as fuel cells, heat management, and batteries. Hydrogen is considered an energy carrier and its chemical energy can be converted into electricity through a chemical reaction with oxygen from a fuel cell. Therefore, coupling energy storage systems with renewable energy sources through an electrolyzer, which can transform electric energy into hydrogen chemical energy, is considered a high sustainable process of production and exploitation of renewable energies. Integrated systems are constituted by a metal hydride tank and a PEM fuel cell, in which the waste heat generated in the fuel cell is used to supply the necessary heat required for desorption of hydrogen from the tank. The field of application of the integrated power system is in combination with renewable sources: The hydrogen can be produced by electrolysis of water using the energy from a renewable source (e.g., photovoltaic); it is then stored and converted into electric energy by the proposed integrated power system, that allows energy storage in the form of hydrogen and its reuse when the renewable source is not available, for example, at night if solar power is exploited. The developed power system could replace batteries and could be applied in the case of a production plant not connected to the power grid, such as in remote areas. As an example, an integrated power system, showing a total energy production of 4.8 kW h, over more than 6 h of working activity, is reported in ref 4. In the SSH2S (Fuel Cell Coupled Solid-State Hydrogen Storage Tank) project, a solid-state hydrogen storage tank based on complex hydrides has been developed and it was fully integrated with a High-Temperature Proton Exchange Membrane (HT-PEM) fuel cell stack. The hydrogen storage tank was designed to feed a 1 kW HT-PEM stack for 2 h to be used for an Auxiliary Power Unit (APU).61 With respect to batteries, hydrides can be utilized as anodes with high capacity (e.g., 2 Ahg-1 for MgH2). A lot of effort has been expended to improve the cyclability, and significant results have been reached in a solid-state battery with LiBH4 solid electrolyte. Demonstration of high-energy density fuel cells with suitable cathodes will be the challenge of upcoming research studies.62,63 As mentioned for the beneficial contribution of electrodes, solid-state electrolytes based on borohydrides are a typical example that the battery community is now taking seriously along with the popular garnet-type solid electrolytes.64,65 It has been demonstrated that the ionic conductivity is a prerequisite for application in batteries, but unfortunately it is not win; in fact, other important issues need to be tackled, such as chemical compatibility, interfaces, heterogeneity, and mechanical properties, so important for the cell engineering and design, in addition to the structural and volumetric changes during cycling. At first, borohydrides meet some of these criteria regarding conductivity and ductility, (thermo)chemistry, and low-density materials. Future research might be directed to the understanding and assessment of interfaces and physical and mechanical properties of the selected solid-electrolyte and electrodes. The specificity of the application may become a determining aspect in the selection of the suitable configuration. Substantial research efforts are being conducted to study new approaches toward the utilization of borohydrides and closo-type complex hydrides in composites.66,67 Thanks to their ductility and ionic conductivity, borohydrides can be also employed as additives for binder-free solid-state batteries. Since the demonstration of LiBH4 thin film growth,68 this could be considered for mitigating the formation of dendrite and oxidation layers on the surface of lithium metal. Another direction is focused on the development of Mg2+ conducting solid electrolytes for application in Mg batteries, which offer higher volumetric capacity compared to lithium at low cost. At present, the technology can be only possible at high-T owing to the low ionic conductivity and Mg2+-ion mobility.69 In addition, metal hydrides can be utilized as optical hydrogen sensors for the detection of hydrogen at low pressure levels according to changes in the optical properties, which is a step forward regarding the increase of the safety for advanced hydrogenbased systems. Lastly, compared to the traditional conferences for hydrogen community (MH, E-MRS, Gordon, etc.) there no doubt that IRSEC is a particular place to meet scientists and experts in the African context undergoing full energy boom. The eighth edition of IRSEC will continue the tradition of drawing the best scientists in the field of sustainable energy, which will be held in Tangier (Morocco), November 25-28, 2020. We thank the local organizers and students, the participants, and the speakers of this Special Session for their excellent contributions. © 2020 American Chemical Society. All rights reserved.","Another direction is focused on the development of Mg2+ conducting solid electrolytes for application in Mg batteries, which offer higher volumetric capacity compared to lithium at low cost. there no doubt that IRSEC is a particular place to meet scientists and experts in the African context undergoing full energy boom.",_
!229,"In addition to serving as an important energy carrier, hydrogen storage material also has the potential to be used as an effective solid reducing agent. This paper is concerned with the application of MgH2/MoS2 hydrogen storage materials to thiophene desulfurization through catalytic transfer hydrogenation. The hydrogen content of the as-prepared MgH2/MoS2 composites is determined to be 6.15 wt% with a dehydrogenation peak temperature of 402 °C. Taking MgH2 as hydrogen donor, thiophene hydrodesulfurization has taken place at atmospheric pressure and at the temperature lower than the onset desorption temperature, indicating that a coupling effect occurs between MgH2 decomposition and thiophene hydrogenation. It is further revealed that sulfur removal in thiophene under the studied condition preferentially proceeds via direct desulfurization (DDS) route. Our density functional theory (DFT) calculations manifest that energy barriers of the minimum energy path for thiophene hydrodesulfurization are all <1.35 eV. This exploratory case study demonstrates the feasibility of catalytic transfer hydrogenation using solid-state hydrogen storage materials. © 2018 Elsevier Ltd",This paper is concerned with the application of MgH2/MoS2 hydrogen storage materials to thiophene desulfurization through catalytic transfer hydrogenation. It is further revealed that sulfur removal in thiophene under the studied condition preferentially proceeds via direct desulfurization (DDS) route.,_
!230,"Absorption of hydrogen gas inside the metal hydride (MH)-based hydrogen storage system generates significant amount of heat. This heat must be removed rapidly to improve the performance of the system which can be accomplished by embedding a heat exchanger inside the MH bed. In this article, a tubular shape MH system, equipped with a heat exchanger consisting of copper tube and pin fin is presented. A detailed 3D mathematical model is developed using COMSOL Multiphysics 4.3b for the numerical study of absorption and desorption processes inside the storage system. Impact of various operating and geometric parameters on the charging time of the storage system has been examined. It is observed that these geometric and operating parameters influence the charging time of the storage system. In the last, the impact of heat exchanger material on the performance of the storage system is explored. It is found that aluminum made heat exchanger is the best for the storage systems. The absorption process is accomplished in 1152 s at the operating parameters of 15 bar, 298 K, and 6.75 lit/min. This numerical work suggests that the efficient design of storage system is very important for rapid absorption and desorption of hydrogen. © 2018, © 2018 Taylor & Francis Group, LLC.","In this article, a tubular shape MH system, equipped with a heat exchanger consisting of copper tube and pin fin is presented. A detailed 3D mathematical model is developed using COMSOL Multiphysics 4.3b for the numerical study of absorption and desorption processes inside the storage system.",_
!231,"Solid-state hydrogen storage technology currently suffers from issues such as inadequate storage capacity, and instability, leading to low performances. Here we show a record of above 2000 mAh.g−1 (∼7.8 wt% H) of discharge capacity of a binary metal oxides Ce0.75Zr0.25O2 nanopowders. The yellowish Ce0.75Zr0.25O2 nanopowders have been synthesized via a sol-gel method under thermal treatment of the molecular precursors of the, (NH4)2Ce(NO3)6 and C16H40O4Zr. The crystal structure and morphology evolution can be described by the cubic and highly pure structure and homogeneous nanoscales formation of Ce0.75Zr0.25O2, ranging from 35 to 60 nm. The formation of the Ce0.75Zr0.25O2 nanoparticles distinctly matches with the spectroscopy results. The activation energy (Ea) was calculated from the output of a reduction thermal programming profile at about 177 kJ mol−1 using Kissinger equation. Our work will promote the development of low-cost solid-state semiconductors based on transition metals, as a host for hydrogen sorption. © 2019 Elsevier B.V.","The activation energy (Ea) was calculated from the output of a reduction thermal programming profile at about 177 kJ mol−1 using Kissinger equation. Our work will promote the development of low-cost solid-state semiconductors based on transition metals, as a host for hydrogen sorption.",_
!232,"Sodium borohydride (NaBH4) is a promising solid-state hydrogen storage material because of its low toxicity, high environmental stability and release of high-purity hydrogen. Nevertheless, the practical application of NaBH4 is still hampered by its high desorption temperature and slow hydrogen exchange kinetics. Using experimental and first-principles calculations approaches, the dehydrogenation properties and modifying mechanisms of NaBH4+10 wt%graphene composite acquired by ball-milling are systematically investigated in this work. The results show that the graphene plays a cooperative catalysis–confinement effect on NaBH4. X-ray diffraction analysis displays that no new phases formed due to the mutual inertia between NaBH4 and graphene during ball-milling. Scanning electron microscopy and transmission electron microscopy observations show that the NaBH4 particles are significantly refined after graphene addition, which effectively restrains the agglomeration of NaBH4 particles. Thermogravimetry testing and mass spectrometry testing indicate that the onset dehydrogenation temperature of the NaBH4+10 wt%graphene composite is decreased by about 114 °C relative to the milled pristine NaBH4. First-principles calculations reveal that the enhanced dehydrogenation properties of NaBH4 after graphene addition should be ascribed to the reduced dehydrogenation enthalpy of NaBH4 and strong binding energy between NaBH4 and graphene as well as the electron transfer from NaBH4 to graphene. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.","Nevertheless, the practical application of NaBH4 is still hampered by its high desorption temperature and slow hydrogen exchange kinetics. X-ray diffraction analysis displays that no new phases formed due to the mutual inertia between NaBH4 and graphene during ball-milling.",_
!233,"The hydrogen storage properties of 6Mg(NH2)2[sbnd]9LiH-x(LiBH4)(x = 0, 0.5, 1, 2)system and the role of LiBH4 on the kinetic behaviour and the dehydrogenation/hydrogenation reaction mechanism were herein systematically investigated. Among the studied compositions, 6Mg(NH2)2[sbnd]9LiH[sbnd]2LiBH4 showed the best hydrogen storage properties. The presence of 2 mol of LiBH4 improved the thermal behaviour of the 6Mg(NH2)2[sbnd]9LiH by lowering the dehydrogenation peak temperature nearly 25 °C and by reducing the apparent dehydrogenation activation energy of about 40 kJ/mol. Furthermore, this material exhibited fast dehydrogenation (10 min)and hydrogenation kinetics (3 min)and excellent cycling stability with a reversible hydrogen capacity of 3.5 wt % at isothermal 180 °C. Investigations on the reaction pathway indicated that the observed superior kinetic behaviour likely related to the formation of Li4(BH4)(NH2)3. Studies on the rate-limiting steps hinted that the sluggish kinetic behaviour of the 6Mg(NH2)2[sbnd]9LiH pristine material are attributed to an interface-controlled mechanism. On the contrary, LiBH4-containing samples show a diffusion-controlled mechanism. During the first dehydrogenation reaction, the possible formation of Li4(BH4)(NH2)3 accelerates the reaction rates at the interface. Upon hydrogenation, this ‘liquid like’ of Li4(BH4)(NH2)3 phase assists the diffusion of small ions into the interfaces of the amide-hydride matrix. © 2019 Hydrogen Energy Publications LLC","Furthermore, this material exhibited fast dehydrogenation (10 min)and hydrogenation kinetics (3 min)and excellent cycling stability with a reversible hydrogen capacity of 3.5 wt % at isothermal 180 °C. On the contrary, LiBH4-containing samples show a diffusion-controlled mechanism.",_
!234,"The effective storage of H2 gas represents one of the major challenges in the wide spread adoption of hydrogen powered fuel cells for light vehicle transportation. Here, we investigate the merits of chemically hydrogenated graphene (graphane) as a means to store high-density hydrogen fuel for on demand delivery. In order to evaluate hydrogen storage at the macroscale, 75 g of hydrogenated graphene was synthesized using a scaled up Birch reduction, representing the largest reported synthesis of this material to date. Covalent hydrogenation of the material was characterized via Raman spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). We go on to demonstrate the controlled release of H2 gas from the bulk material using a sealed pressure reactor heated to 600 °C, identifying a bulk hydrogen storage capacity of 3.2 wt%. Additionally, we demonstrate for the first time, the successful operation of a hydrogen fuel cell using chemically hydrogenated graphene as a power source. This work demonstrates the utility of chemically hydrogenated graphene as a high-density hydrogen storage medium, and will be useful in the design of prototype hydrogen storage systems moving forward. © 2019","Here, we investigate the merits of chemically hydrogenated graphene (graphane) as a means to store high-density hydrogen fuel for on demand delivery. Covalent hydrogenation of the material was characterized via Raman spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA).",_
!235,"Reaction kinetic behaviour and cycling stability of the 2LiBH4-MgH2 reactive hydride composite (Li-RHC) are experimentally determined and analysed as a basis for the design and development of hydrogen storage tanks. In addition to the determination and discussion about the properties; different measurement methods are applied and compared. The activation energies for both hydrogenation and dehydrogenation are determined by the Kissinger method and via the fitting of solid-state reaction kinetic models to isothermal volumetric measurements. Furthermore, the hydrogen absorption-desorption cycling stability is assessed by titration measurements. Finally, the kinetic behaviour and the reversible hydrogen storage capacity of the Li-RHC are discussed. © 2018 by the authors.","Reaction kinetic behaviour and cycling stability of the 2LiBH4-MgH2 reactive hydride composite (Li-RHC) are experimentally determined and analysed as a basis for the design and development of hydrogen storage tanks. Furthermore, the hydrogen absorption-desorption cycling stability is assessed by titration measurements.",_
!236,"This work discusses the influence of different metal hydride storage bed configurations. The objective was to design and optimize a solid-state hydrogen storage for a nonpolluting mobility. A study of the absorption and desorption dynamics of a loose powder bed was performed first, followed by three different storage bed configurations: compacted Ti-Mn alloy powder, alternated Ti-Mn alloy compacts with stainless steel fins and compacted [Ti-Mn alloy/Stainless steel] powder mixture. A numerical model was developed to simulate the heat transfer and the hydrogen absorption and desorption rates. The alternation and compact mixture configurations gave better heat transfer efficiencies, absorption and desorption rates and increased hydrogen storage densities. Indeed, an efficient heat transfer (between the tank and its surrounding fluid), a tailored porosity of the metal hydride storage bed and the addition of high thermal conductivity materials allowed the overall storage performance to be improved. Thus, the required time for loading/unloading hydrogen was reduced drastically. The alternation configuration would offer the additional advantage of a simple, inexpensive and efficient recycling procedure. © 2019","This work discusses the influence of different metal hydride storage bed configurations. A study of the absorption and desorption dynamics of a loose powder bed was performed first, followed by three different storage bed configurations: compacted Ti-Mn alloy powder, alternated Ti-Mn alloy compacts with stainless steel fins and compacted [Ti-Mn alloy/Stainless steel] powder mixture.",_
!237,"The features of gas discharge and plasma sources based on Penning trap with metal hydride cathodes are presented. In such devices, metal hydrides fulfill the functions of both a cathode and the solid-state generator of working gas. Their advantages are high purity of gas injected (99.99 - 99.999%), along with the safety and compactness in storage. Hydrogen is injected (desorbed) locally under the influence of ion bombardment of metal hydride surface, which fact provides return coupling between the intensity of gas desorption and the parameters of gas discharge. The rate of sputtering for those materials by plasma ions significantly reduces as well as heat loads. Above effect is achieved due to the creation of protective gas target as a result of both the thermal decomposition of metal hydride and ion stimulated desorption. The feature of metal hydride cathode under the conditions of gas discharge is a decrease in the ionization potential of desorbed hydrogen by 0.3-0.5 eV due to the molecules desorption in the vibrationally/rotationally excited state. This permits a substantially increase in ionization efficiency and the formation of negative ions by the mechanism of dissociative attachment in plasma volume. However, hydrogen desorbed from metal hydride significantly changes the properties of the discharge. This is expressed, for example, in the fact that the plasma source based on Penning trap with metal hydride cathode appears to generate current-compensated ion beams with the ability to control the energy of the extracted ions. There is also the opportunity of longitudinal extraction of negative hydrogen ions against the traditional method of extraction across the magnetic field. © 2018 Nova Science Publishers, Inc.","The features of gas discharge and plasma sources based on Penning trap with metal hydride cathodes are presented. Their advantages are high purity of gas injected (99.99 - 99.999%), along with the safety and compactness in storage.",_
!238,"Hydrogen storage is vital for use in fuel cells and nuclear thermal rockets (NTR), both of which benefit from low-energy reservoirs available for long durations. A novel method of solid-state storage using catalytically-modified porous silicon can be fabricated entirely from materials found on the Moon and in asteroids, requiring only a fixed quantity of reusable reagents to be brought from Earth. Consumables include silicon, aluminum, iron, and water, all of which can be extracted from suitable regolith ore bodies. An aluminum pressure vessel containing granular porous silicon particles is recharged by hydrogen pressures of 0.8 MPa. Once charged, the hydrogen storage subsystem can be maintained at any temperature from 0 to 373 K for an indefinite period, suitable for lunar nights or months-long trips to main-belt asteroids. Discharge is facilitated by heating above 393 K, provided by IR, resistive, or metal foam heat conductors embedded in the particulate bed. Systems-level volumetric and gravimetric storage metrics are 39 g/l and 5.8 percent w/w, respectively, comparable to cryogenic hydrogen storage in size and mass. The embodied energy in storing the hydrogen is very small, less than 2 percent of the embodied chemical energy, which makes it more efficient than cryogenic at 40 percent. Silicon and aluminum can be extracted from regolith using isotopic separation by charge/mass ratio. Iron and nickel are harvested from lunar regolith by electromagnets and used as the catalyst to mediate between gaseous hydrogen and monatomic surface adsorbed hydrogen. Deposition is accomplished via carbonyl gases, which require a quantity of CO, which is recovered after each use. Making the silicon porous requires hydrofluoric acid (HF), which will need to be supplied from Earth. The hydrofluorosilicic acid byproduct can be heated to decompose into HF vapor and silicon dioxide. The HF is condensed and re-used, and the silicon dioxide is a waste byproduct, which can be formed into quartz objects such as portals and glassware. A lunar factory with a mass of 7.5 MT can produce complete hydrogen storage vessels, assuming that electronic control can be provided by the remainder of the power system. With granular media, the size and shape of such vessels are essentially constrained. One example is two-meter thick shell sections for a deep space crew cabin for radiation protection. The hydrogen therein could be withdrawn as a back-up supply of fuel, or for a final Hohman transfer burn just before refueling. © 2020 by the International Astronautical Federation (IAF). All rights reserved.","Consumables include silicon, aluminum, iron, and water, all of which can be extracted from suitable regolith ore bodies. An aluminum pressure vessel containing granular porous silicon particles is recharged by hydrogen pressures of 0.8 MPa.",_
!239,"Renewable energy sources are becoming more and more widespread and practical used, but it is difficult to plan and stabilize the process of obtaining and storing this kind of energy. The hydrogen like an energy carrier is a possible decision for stable energy storage. Thanks to the hydrogen solid state storage systems based on metal hydrides is possible to store the energy, comes from renewable sources under safety and easy conditions. Historical methods of hydrogen storage like compression and liquefaction, which are established and developed now, still bring big safety problems and associated high costs of compression and cooling. © 2018 IEEE.","The hydrogen like an energy carrier is a possible decision for stable energy storage. Thanks to the hydrogen solid state storage systems based on metal hydrides is possible to store the energy, comes from renewable sources under safety and easy conditions.",_
!240,"A solid-state hydrogen storage material comprising ammonia borane (AB) and polyethylene oxide (PEO) has been produced by freeze-drying from aqueous solutions from 0% to 100% AB by mass. The phase mixing behaviour of AB and PEO has been investigated using X-ray diffraction which shows that a new ‘intermediate’ crystalline phase exists, different from both AB and PEO, as observed in our previous work (Nathanson et al., 2015). It is suggested that hydrogen bonding interactions between the ethereal oxygen atom (–O–) in the PEO backbone and the protic hydrogen atoms attached to the nitrogen atom (N–H) of AB molecules promote the formation of a reaction intermediate, leading to lowered hydrogen release temperatures in the composites, compared to neat AB. PEO also acts to significantly reduce the foaming of AB during hydrogen release. A temperature-composition phase diagram has been produced for the AB-PEO system to show the relationship between phase mixing and hydrogen release. © 2018 The Author(s)","The phase mixing behaviour of AB and PEO has been investigated using X-ray diffraction which shows that a new ‘intermediate’ crystalline phase exists, different from both AB and PEO, as observed in our previous work (Nathanson et al., 2015). PEO also acts to significantly reduce the foaming of AB during hydrogen release.",_
!241,"Intermetallic compounds are key materials for energy transition as they form reversible hydrides that can be used for solid state hydrogen storage or as anodes in batteries. ABy compounds (A = Rare Earth (RE); B = transition metal; 2 < y < 5) are good candidates to fulfill the required properties for practical applications. They can be described as stacking of [AB5] and [AB2] sub-units along the c crystallographic axis. The latter sub-unit brings a larger capacity, while the former one provides a better cycling stability. However, ABy binaries do not show good enough properties for applications. Upon hydrogenation, they exhibit multiplateau behavior and poor reversibility, attributed to H-induced amorphization. These drawbacks can be overcome by chemical substitutions on the A and/or the B sites leading to stabilized reversible hydrides. The present work focuses on the pseudo-binary Sm2MnxNi7-x system (0 ≤ x < 0.5). The structural, thermodynamic and corrosion properties are analyzed and interpreted by means of X-ray diffraction, chemical analysis, scanning electron microscopy, thermogravimetric analysis and magnetic measurements. Unexpected cell parameter variations are reported and interpreted regarding possible formation of structural defects and uneven Mn distribution within the Ni sublattice. Reversible capacity is improved for x > 0.3 leading to larger and flatter isotherm curves, allowing for reversible capacity >1.4 wt %. Regarding corrosion, the binary compound corrodes in alkaline medium to form rare earth hydroxide and nanoporous nickel. As for the Mn-substituted compounds, a new corrosion product is formed in addition to those above mentioned, as manganese initiates a sacrificial anode mechanism taking place at the early corrosion stage.  © 2020 by the authors.","ABy compounds (A = Rare Earth (RE); B = transition metal; 2 < y < 5) are good candidates to fulfill the required properties for practical applications. Regarding corrosion, the binary compound corrodes in alkaline medium to form rare earth hydroxide and nanoporous nickel.",_
!242,"The secondary energy sources, like hydrogen, is a key enabling energy carrier for the advancement of fuel cell technology. Hydrogen has a low volumetric energy density; therefore, its transportation is costly, and requires a large area. Solid-state hydrogen storage is a key solution for the promoting hydrogen in stationary power, portable power, and transportation applications. To keep these challenges up, this paper integrates production design of a novel solid-state-nanosized-mixed metal oxides (MMOs), CuCe2(MoO4)4 nanostructures via Pechini method, structural and morphological assessments, and its respective hydrogen storage properties. The electrochemical properties of the samples with morphological diversity have unveiled an exceeded discharge capacity (∼1320 mA h/g) of the sample which designed in neutral medium (pH = 7), having a specific surface area of 7.90 m2 g−1 and mean pore size of 37.07 nm. © 2020 Elsevier B.V.","The secondary energy sources, like hydrogen, is a key enabling energy carrier for the advancement of fuel cell technology. To keep these challenges up, this paper integrates production design of a novel solid-state-nanosized-mixed metal oxides (MMOs), CuCe2(MoO4)4 nanostructures via Pechini method, structural and morphological assessments, and its respective hydrogen storage properties.",_
!243,"Hydrogen has been considered as a potential candidate for the replacement of fossil fuels in future due to its renewability, abundance, ease in production, environmental friendliness and high energy efficiency. In this regard, chemical storage of hydrogen in solid state of metal hydrides is the safest method for stationary and portable applications since these can be functioned at lower pressure and ambient temperature. Among the desirable metal hydrides, the intermetallic compound TiFe of cubic CsCl-type structure is well known for absorbing hydrogen reversibly up to 1.9 wt.% to form β-FeTiH and γ-FeTiH2 phases. In this paper, we have discussed the historic background outlining the recent developments on the microstructural modifications, activation kinetics and processing routes of TiFe intermetallic alloys toward the improvement of hydrogenation properties. An in-depth microstructural analysis of TiFe alloys has been presented in terms of crystallography, hydride phase formation and hydrogenation mechanisms. The rate-controlling steps for the mechanisms of (de)hydrogenation processes of TiFe intermetallics have been explained in details. It was found that the rate-controlling steps of the hydriding reaction were dependent on the fraction of β-hydride phase. Intensive research activities were carried out to improve the first hydrogenation kinetics that can be categorized into two groups: alloying and mechanical activation. The mechanisms for improved hydrogenation kinetics in both cases have been explained. Lastly, various fabrication processes to produce TiFe alloys have been presented and correlated with cost-effectiveness and hydrogen-storage capability. Therefore, the focus of this article is to present the basic knowledge and recent developments on TiFe intermetallic alloys for future hydrogen-storage applications which will be beneficial to researchers and practitioners in the field of interest. © 2019 Taylor & Francis Group, LLC.","In this regard, chemical storage of hydrogen in solid state of metal hydrides is the safest method for stationary and portable applications since these can be functioned at lower pressure and ambient temperature. Intensive research activities were carried out to improve the first hydrogenation kinetics that can be categorized into two groups: alloying and mechanical activation.",_
!244,"Hydrogen is an ideal energy carrier because of its high chemical energy, environmental friendliness and renewability. In order to realize the safe, efficient and compact hydrogen storage, various solid-state hydrogen storage materials based on the physisorption or chemisorption of hydrogen have been developed over the past decades. Among them, magnesium hydride, MgH2, is identified as one of the most promising candidates due to its high hydrogen storage density, low cost and abundance of Mg element. However, the sluggish kinetics and high thermodynamic stability of MgH2 result in its high operation temperature and low hydrogen sorption rate, impeding its practical application. In this article, the recent progress in catalysis and nanoconfinement effects on the hydrogen storage properties of MgH2 is comprehensively reviewed. In particular, the synergetic roles of catalysis and nanoconfinement in MgH2 are highlighted. Furthermore, the future challenges and prospects of emerging research for MgH2 are discussed. It is suggested that the nonmetal-doped porous carbon materials could be a class of ideal additives to enhance the hydrogen storage properties of MgH2 by the synergetic effects of catalysis and nanoconfinement. © 2017 Hydrogen Energy Publications LLC","Among them, magnesium hydride, MgH2, is identified as one of the most promising candidates due to its high hydrogen storage density, low cost and abundance of Mg element. Furthermore, the future challenges and prospects of emerging research for MgH2 are discussed.",_
!245,"Characterising the hydrogen sorption properties of materials is important for a range of applications, including solid state hydrogen storage, electrochemical and thermal energy storage using metal hydrides, and H2 gas compression and purification. However, it can be technically demanding and subject to significant error if not performed with care. In this article, potential pitfalls in the performance of hydrogen sorption measurements are discussed. The topics covered include instrument design and calibration, sample size choice, sample and gas purity, isotherm measurement procedure and issues associated with data reduction. Approaches to validating equipment and isotherm measurements are also discussed. Different sample types are considered, including metal and complex hydrides and nanoporous adsorbents, such as porous carbons, zeolites and metal-organic frameworks (MOFs). © 2017 Hydrogen Energy Publications LLC","However, it can be technically demanding and subject to significant error if not performed with care. Approaches to validating equipment and isotherm measurements are also discussed.",_
!246,"The pyroelectric effect is commonly used to construct infrared radiation detectors. To pay attention to the possibility of using this phenomenon in materials based on relaxor-ferroelectric such as Pb(Mg1/3Nb2/3)1-xTixO3 (lead titanium-lead magnesium niobate), single crystals from solid solution were grown using modified Bridgman method with x taken three different range (x = 0.25, 0.33 and 0.40). In this work the operation principles for pyroelectric sensor and their properties are presented, with a brief review on the temperature stability of the Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–xPT)single crystals. It was shown that the pyroelectric and dielectric properties are strongly dependent on composition (PT content), as well as the temperature variation. The investigations have revealed that the best choice for pyroelectric performances is <111>oriented PMN–0.25 PT, although, the PMN–0.33 PT and PMN–0.40 PT owns much better temperature stability, and higher Curie temperature Tc. The PMN–xPT single crystals showed promising pyroelectric performances, they can be used as thermal sensors and may be associated with temperature management systems to improve the performance of solid state hydrogen reactors. © 2019 Hydrogen Energy Publications LLC","To pay attention to the possibility of using this phenomenon in materials based on relaxor-ferroelectric such as Pb(Mg1/3Nb2/3)1-xTixO3 (lead titanium-lead magnesium niobate), single crystals from solid solution were grown using modified Bridgman method with x taken three different range (x = 0.25, 0.33 and 0.40). The PMN–xPT single crystals showed promising pyroelectric performances, they can be used as thermal sensors and may be associated with temperature management systems to improve the performance of solid state hydrogen reactors.",_
!247,"De/rehydrogenation performances and reaction pathways of nanoconfined 2LiBH4[sbnd]MgH2 into activated carbon (AC) packed in small hydrogen storage tank are proposed for the first time. Total and material storage capacities upon five hydrogen release and uptake cycles are 3.56–4.55 and 2.03–3.28 wt % H2, respectively. Inferior hydrogen content to theoretical capacity (material capacity of 5.7 wt % H2) is due to partial dehydrogenation during sample preparation and incomplete decomposition of LiBH4 as well as the formation of thermally stable Li2B12H12 upon cycling. Two-step dehydrogenation of MgH2 and LiBH4 to produce Mg and MgB2+LiH, respectively is found at all positions in the tank. For rehydrogenation, reversibility of MgH2 and LiBH4 proceeds via different reaction mechanisms. Although isothermal condition (Tset = 350 °C) and controlled pressure range (e.g., 30–40 bar H2 for hydrogenation) are applied, temperature gradient inside the tank and poor hydrogen diffusion through hydride bed, especially in the sample bulk are detected. This results in alteration of de/rehydrogenation pathways of hydrides at different positions in the tank. Thus, further development of hydrogen storage tank based 2LiBH4[sbnd]MgH2 nanoconfined in AC includes the improvement of thermal conductivity of materials and temperature control system as well as hydrogen permeability. © 2019 Hydrogen Energy Publications LLC","De/rehydrogenation performances and reaction pathways of nanoconfined 2LiBH4[sbnd]MgH2 into activated carbon (AC) packed in small hydrogen storage tank are proposed for the first time. Although isothermal condition (Tset = 350 °C) and controlled pressure range (e.g., 30–40 bar H2 for hydrogenation) are applied, temperature gradient inside the tank and poor hydrogen diffusion through hydride bed, especially in the sample bulk are detected.",_
!248,"LaNi5 alloy can be utilized to directly store and release hydrogen in mild condition, thus it is considered as a long-term safe and stable solid-state hydrogen storage material. In this work, LaNi5H5 was used as the solid-state hydrogen source in the CO2 methanation reaction. Impressively, the carbon dioxide conversion can be achieved to nearly 100% under 3 MPa mixed gas at 200 °C. The microstructure and composition analysis results reveal that the high catalytic activity may originate from the promoted elementary steps over in situ formed metallic Ni nanoparticles during the CO2 methanation process. More importantly, as the lowered reaction temperature prevented the agglomeration of Ni nanoparticles, this catalyst exhibited durable stability with 99% conversion rate of CO2 retained after 400 h cycling test. © 2019 Hydrogen Energy Publications LLC","Impressively, the carbon dioxide conversion can be achieved to nearly 100% under 3 MPa mixed gas at 200 °C. More importantly, as the lowered reaction temperature prevented the agglomeration of Ni nanoparticles, this catalyst exhibited durable stability with 99% conversion rate of CO2 retained after 400 h cycling test.",_
!249,"Solid-state hydrogen storage materials undergo complex phase transformations whose behavior are collectively determined by thermodynamic (e.g., Gibbs free energy), mechanical (e.g., lattice and elastic constants), and mass transport (e.g., diffusivity) properties. These properties depend on the reaction conditions and evolve continuously during (de)hydrogenation. Thus, they are difficult to measure in experiments. Because of this, past progress to improve solid-state hydrogen storage materials has been prolonged. Using PdHx as a representative example for interstitial metal hydride, we have recently applied molecular dynamics simulations to quantify hydrogen diffusion in the entire reaction space of temperature and composition. Here, we have further applied molecular dynamics simulations to obtain well-converged expressions for lattice constants, Gibbs free energies, and elastic constants of PdHx at various stages of the reaction. Our studies confirm significant dependence of elastic constants on temperature and composition. Specifically, a new dynamic effect of hydrogen diffusion on elastic constants is discovered and discussed. © 2018 U.S. Government.","Using PdHx as a representative example for interstitial metal hydride, we have recently applied molecular dynamics simulations to quantify hydrogen diffusion in the entire reaction space of temperature and composition. Specifically, a new dynamic effect of hydrogen diffusion on elastic constants is discovered and discussed.",_
!250,"Hydrogen storage in the solid state represents one of the most attractive and challenging ways to supply hydrogen to a proton exchange membrane (PEM) fuel cell. Although in the last 15 years a large variety of material systems have been identified as possible candidates for storing hydrogen, further efforts have to be made in the development of systems which meet the strict targets of the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and U.S. Department of Energy (DOE). Recent projections indicate that a system possessing: (i) an ideal enthalpy in the range of 20-50 kJ/mol H2, to use the heat produced by PEM fuel cell for providing the energy necessary for desorption; (ii) a gravimetric hydrogen density of 5 wt. % H2 and (iii) fast sorption kinetics below 110 °C is strongly recommended. Among the known hydrogen storage materials, amide and imide-based mixtures represent the most promising class of compounds for on-board applications; however, some barriers still have to be overcome before considering this class of material mature for real applications. In this review, the most relevant progresses made in the recent years as well as the kinetic and thermodynamic properties, experimentally measured for the most promising systems, are reported and properly discussed. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.","Hydrogen storage in the solid state represents one of the most attractive and challenging ways to supply hydrogen to a proton exchange membrane (PEM) fuel cell. Among the known hydrogen storage materials, amide and imide-based mixtures represent the most promising class of compounds for on-board applications; however, some barriers still have to be overcome before considering this class of material mature for real applications.",_
!251,"Polygeneration Microgrids (PMG) can be configured to deliver multiple outputs such as, electricity, heat, cold, fuel (hydrogen) and clean water. In an earlier paper the authors presented an analysis of a PMG consisting of solar photovoltaic field, fuel cell, solid state hydrogen storage and electrolyzer using commercial software HOMER. Keeping in mind the fact that battery storage is preferred for stand-alone microgrids, in this paper, the influence of battery storage on the performance of a PMG is presented. An added advantage of solid state hydrogen storage – fuel cell system is the availability heat released during adsorption of metal hydride in addition to that rejected by the fuel cell. A comparison of battery alone versus battery + fuel cell is made. © 2020 Elsevier Ltd","Polygeneration Microgrids (PMG) can be configured to deliver multiple outputs such as, electricity, heat, cold, fuel (hydrogen) and clean water. An added advantage of solid state hydrogen storage – fuel cell system is the availability heat released during adsorption of metal hydride in addition to that rejected by the fuel cell.",_
!252,"Magnesium hydride (MgH2) and titanium hydride (TiH2) are two potential candidates for solid-state hydrogen storage, but strong hydride formation energy in these hydrides undesirably results in their high dehydrogenation temperature. First-principles calculations show that the metastable hydrides in the MgH2–TiH2 system have low hydrogen binding energy, which makes them more appropriate for low-temperature hydrogen storage. In this study, severe plastic deformation (SPD) via the high-pressure torsion (HPT) method is applied to the MgH2–TiH2 system to synthesize metastable hydrides. While MgH2 transforms to a high-pressure orthorhombic γ phase, TiH2 does not exhibit any cubic-to-tetragonal phase transformation even by HPT processing at cryogenic temperature. Application of large strains by 400 HPT turns to the immiscible MgH2/TiH2 composite results in atomic-scale mixing and formation of nanostructured ternary Mg–Ti–H hydride with the metastable FCC structure and lower dehydrogenation temperature than TiH2. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim","First-principles calculations show that the metastable hydrides in the MgH2–TiH2 system have low hydrogen binding energy, which makes them more appropriate for low-temperature hydrogen storage. Application of large strains by 400 HPT turns to the immiscible MgH2/TiH2 composite results in atomic-scale mixing and formation of nanostructured ternary Mg–Ti–H hydride with the metastable FCC structure and lower dehydrogenation temperature than TiH2.",_
!253,"Hydrogen, which holds tremendous promise as a new clean energy option is considered as an efficient source of primary energy. Unluckily, hydrogen storage presents the most crucial difficulty restricting utilization of hydrogen energy for real applications. However, Mg metal is the best known cheap solid-state hydrogen storage media with high hydrogen capacity and operational cost effectiveness; it shows high thermal stability and poor hydrogenation/dehydrogenation kinetics. In the present work we have succeeded to prepare nanocrystalline MgH2 powders doped with a mixture of 8 wt% Nb2O5/2 wt% Ni nanocatalytic system. The synthesized nanocomposite powders possessed superior hydrogenation/dehydrogenation kinetics (2.6 min/3 min) at relatively low temperature (250 °C) with long cycle-life-time (400 h). The powders were consolidated into green-compacts, using cold pressing technique. The compacts were utilized as solid-state hydrogen source needed for charging a battery of a cell-phone device, using integrated Ti-tank/commercial proton-exchange membrane fuel cell system. © 2018 Hydrogen Energy Publications LLC","However, Mg metal is the best known cheap solid-state hydrogen storage media with high hydrogen capacity and operational cost effectiveness; it shows high thermal stability and poor hydrogenation/dehydrogenation kinetics. The synthesized nanocomposite powders possessed superior hydrogenation/dehydrogenation kinetics (2.6 min/3 min) at relatively low temperature (250 °C) with long cycle-life-time (400 h).",_
!254,"The present work reports for the first time application of cold spray coating for doping plastically deformed Mg-strips by different concentrations of fine Ni powders. For present study, Mg rods were cold-rolled for 300 passes and then coated by Ni fine powders, using a cold spray process operated at 150 °C under high argon gas pressure. The Ni powders were pelted into Mg-substrate through the high-velocity jet at a speed of 500 m/s. Under these preparation conditions, Ni powders were plastically deformed at the surface of Mg strips to create numerous pores and cavities, worked as hydrogen diffusion gateway. The as-coated Mg sheets with 3-Ni layers (5.28 wt%) possessed good hydrogenation/dehydrogenation kinetics, implied by a short absorption/desorption time (5.1/11 min) of 6.1 wt% hydrogen at 150 °C/10 bar and 200 °C/200 mbar, respectively. The fabricated solid-state hydrogen storage nanocomposite strips revealed good cyclability of achieving 600 cycles at 200 °C without failure of degradation. © 2019 Hydrogen Energy Publications LLC","For present study, Mg rods were cold-rolled for 300 passes and then coated by Ni fine powders, using a cold spray process operated at 150 °C under high argon gas pressure. Under these preparation conditions, Ni powders were plastically deformed at the surface of Mg strips to create numerous pores and cavities, worked as hydrogen diffusion gateway.",_
!255,"Alkali hydrazinidoboranes MN2H3BH3 (M = Li, Na, K, Rb) have been developed for hydrogen storage. To complete the family of MN2H3BH3, we focused on cesium hydrazinidoborane CsN2H3BH3 (CsHB). It has been synthesized by reaction of cesium with hydrazine borane (N2H4BH3) at −20 °C under inert atmosphere, and it has been characterized. A crystalline solid (monoclinic, s.g. P21 (No. 4)) has been obtained. Its potential for hydrogen storage has been studied by combining different techniques. It was found that, under heating at constant heating rate (5 °C min−1) or at constant temperature (e.g. 120 °C), CsHB decomposes rather than it dehydrogenates. It releases several unwanted gaseous products (e.g. NH3, B2H6) together with H2, and transforms into a residue that poses safety issues because of shock-sensitivity and reactivity towards O2/H2O. Though the destabilization brought by Cs+ onto the anion [N2H3BH3]− has been confirmed, the effect is not efficient enough to avoid the aforementioned drawbacks. All of our results are presented herein and discussed within the context of solid-state hydrogen storage. © 2020 Hydrogen Energy Publications LLC","Alkali hydrazinidoboranes MN2H3BH3 (M = Li, Na, K, Rb) have been developed for hydrogen storage. Its potential for hydrogen storage has been studied by combining different techniques.",_
!256,"It is known that the hydrogen has a very high mass energy density, in fact, that it is a lightest gas; therefore, its storage is a great problem. The aim of the hydrogen storage technologies is thus to reduce the volume that hydrogen occupies in its thermodynamically stable state under conditions close to ambient salt. Recent work on hydrogen storage is mainly based on the use of metal hydrides. These metal hydrides have a high capacity for the hydrogen storage in the operating conditions. The effecting parameters on the performance of such a metal-hydrogen reactor are its design and configuration. In this case, there are a number of problems that need to be considered in designing a reactor. Among these parameters are the reactor configuration, the thermal and the mechanical strength, the kinetics of hydrogen storage and the security. Our study is concentrated on the problem of the thermal and the mechanical strength while focusing on the nature of the metal makes the reactor. In this work, the experimental studies of the hydrogen absorption phenomenon in different reactors, based on metal hydrides, were evaluated. The characteristics of the reaction kinetics in three different reactors using the same measurement conditions were compared. A numerical model describing the reaction kinetic of the H2 absorption by LaNi5 alloy validates the results were obtained. Of these results, it is found that the rate constant varies from one reactor to another. Moreover, the activation energy of the absorption kinetics were identified. © 2017","In this work, the experimental studies of the hydrogen absorption phenomenon in different reactors, based on metal hydrides, were evaluated. Of these results, it is found that the rate constant varies from one reactor to another.",_
!257,"Hydrogen as an energy carrier is very versatile in energy storage applications. Developments in novel, sustainable technologies towards a CO2-free society are needed and the exploration of all-solid-state batteries (ASSBs) as well as solid-state hydrogen storage applications based on metal hydrides can provide solutions for such technologies. However, there are still many technical challenges for both hydrogen storage material and ASSBs related to designing low-cost materials with low-environmental impact. The current materials considered for all-solid-state batteries should have high conductivities for Na+, Mg2+ and Ca2+, while Al3+-based compounds are often marginalised due to the lack of suitable electrode and electrolyte materials. In hydrogen storage materials, the sluggish kinetic behaviour of solid-state hydride materials is one of the key constraints that limit their practical uses. Therefore, it is necessary to overcome the kinetic issues of hydride materials before discussing and considering them on the system level. This review summarizes the achievements of the Marie Sklodowska-Curie Actions (MSCA) innovative training network (ITN) ECOSTORE, the aim of which was the investigation of different aspects of (complex) metal hydride materials. Advances in battery and hydrogen storage materials for the efficient and compact storage of renewable energy production are discussed. © 2020 by the authors.","Developments in novel, sustainable technologies towards a CO2-free society are needed and the exploration of all-solid-state batteries (ASSBs) as well as solid-state hydrogen storage applications based on metal hydrides can provide solutions for such technologies. However, there are still many technical challenges for both hydrogen storage material and ASSBs related to designing low-cost materials with low-environmental impact.",_
!258,"Hydrogen storage in transition mixed metal oxides (MMOs) are predicted from their tendency for adsorption-desorption hydrogen. Hydrogen itself requires initial forces pressure for initiation of condensation. MMOs, based on their effective immobilization matrices, are potential nanocatalysts for energy storage. Even various materials are highlighted for hydrogen storage; however, their adsorption capacities are insufficient for real applications. Here we report, for the first time, a novel hydrogen storage MMOs (Sr2Co9O14 nanoparticles) potential for physical hydrogen sorption, containing a redox species. This polycrystalline nanoparticle is prepared via a combustion method in the presence of various fuels like glucose, fructose, sucrose, lactose, and maltose. The glucose supports the pure and homogenous formation of Sr2Co9O14 nanoparticles consisting the particles less than 100 nm. Interestingly, a maximum discharge capacity of around 950 mA h/g at room temperature has recorded; emphasizing Sr2Co9O14 nanoparticles is a potential substrate for hydrogen storage. © 2019 Hydrogen Energy Publications LLC","MMOs, based on their effective immobilization matrices, are potential nanocatalysts for energy storage. This polycrystalline nanoparticle is prepared via a combustion method in the presence of various fuels like glucose, fructose, sucrose, lactose, and maltose.",_
!259,"To enhance the dehydrogenation/rehydrogenation kinetic behavior of the LiBH4-MgH2 composite system, TiF4 is used as an additive. The effect of this additive on the hydride composite system has been studied by means of laboratory and advanced synchrotron techniques. Investigations on the synthesis and mechanism upon hydrogen interaction show that the addition of TiF4 to the LiBH4-MgH2 composite system during the milling procedure leads to the in situ formation of well-distributed nanosized TiB2 particles. These TiB2 nanoparticles act as nucleation agents for the formation of MgB2 upon dehydrogenation process of the hydride composite system. The effect of TiB2 nanoparticles is maintained upon cycling. © 2018 American Chemical Society.",The effect of this additive on the hydride composite system has been studied by means of laboratory and advanced synchrotron techniques. The effect of TiB2 nanoparticles is maintained upon cycling.,_
!260,"This paper presents the results related to the investigation of layers of nanocrystalline silicon carbide (nc-SiC) obtained by direct ion deposition for the purpose of hydrogen accumulation. The parameters of the production process providing the largest amount of accumulated hydrogen (more than 5.5 wt.%) were determined based on the mass spectrometric data on the desorption of atomic and molecular hydrogen from nc-SiC films. Electron microscopic examination revealed the structural features that are responsible for absorption, retention, and desorption of hydrogen at relatively low temperatures and pressures. The study results suggest that the main structural elements acting as the hydrogen traps are the vacant positions of carbon in nc-SiC. The presence of a developed system of intercrystalline boundaries in investigated films promotes the hydrogen desorption at relatively low temperatures. Copyright © 2018 A. Guglya et al.","Electron microscopic examination revealed the structural features that are responsible for absorption, retention, and desorption of hydrogen at relatively low temperatures and pressures. The presence of a developed system of intercrystalline boundaries in investigated films promotes the hydrogen desorption at relatively low temperatures.",_
!261,"Hydrogen storage in solids of hydrides is advantageous in comparison to gaseous or liquid storage. Magnesium based materials are being studies for solid-state hydrogen storage due to their advantages of high volumetric and gravimetric hydrogen storage capacity. However, unfavorable thermodynamic and kinetic barriers hinder its practical application. In this work, we presented that kinetics of Mg-based composites were significantly improved during high energy ball milling in presence of various types of carbon, including plasma carbon produced by plasma-reforming of hydrocarbons, activated carbon, and carbon nanotubes. The improvement of the kinetics and de-/re-hydrogenation performance of MgH2 and TiC-catalysed MgH2 by introduction of carbon are strongly dependent on the milling time, amount of carbon and carbon structure. The lowest dehydrogenation temperature was observed at 180 °C by the plasma carbon–modified MgH2/TiC. We found that nanoconfinement of carbon structures stabilised Mg-based nanocomposites and hinders the nanoparticles growth and agglomeration. Plasma carbon was found to show better effects than the other two carbon structures because the plasma carbon contained both few layer graphene sheets that served as an active dispersion matrix and amorphous activated carbons that promoted the spill-over effect of TiC catalysed MgH2. The strategy in enhancing the kinetics and thermodynamics of Mg-based composites is leading to a better design of metal hydride composites for hydrogen storage. © 2018 Hydrogen Energy Publications LLC",Plasma carbon was found to show better effects than the other two carbon structures because the plasma carbon contained both few layer graphene sheets that served as an active dispersion matrix and amorphous activated carbons that promoted the spill-over effect of TiC catalysed MgH2. The strategy in enhancing the kinetics and thermodynamics of Mg-based composites is leading to a better design of metal hydride composites for hydrogen storage.,_
!262,"Mg-based hybrids have shown promise via enhanced hydrogen storage properties. The Mg–Mg2Ni-carbon hybrid can be synthesized by accumulative roll bonding (ARB), which is amenable to ‘scaled-up’ synthesis. In spite of the ‘bulk’ nature of the samples synthesized, they display fast kinetics of absorption and desorption of hydrogen. In the current work, we try to comprehend the basis for the same in terms of the activation energy of the underlying processes involved; via desorption curves (wt.% H - time curves) in a Sievert's apparatus and differential scanning calorimetry (heat evolved - T plots). Analysis invoking the Johnson-Mehl-Avrami model and Kissinger plots show that the significantly reduced activation energy for the dehydrogenation process in the hybrid is responsible for the rapid kinetics. It is evinced that admixing the additives with Mg, coupled with fine scale microstructure rich in interfaces is responsible for the fast kinetics. It is established that the rate limiting step for hydrogen desorption is interface migration and not the diffusion of hydrogen, which is governed by the JMA-3D model. © 2020 Hydrogen Energy Publications LLC","Mg-based hybrids have shown promise via enhanced hydrogen storage properties. The Mg–Mg2Ni-carbon hybrid can be synthesized by accumulative roll bonding (ARB), which is amenable to ‘scaled-up’ synthesis.",_
!263,"Solid-state hydrogen storage may be the only promising way for mobile applications of hydrogen energy since it is safe, quickly reversible, cost-efficient, and has a high volumetric energy density under standard conditions. Silsesquioxane and its derivatives seem well suited for solid-state hydrogen storage and have attracted many experimental and theoretical researchers. In the present work, we have systematically studied four cages of T8, T10, and T12 (D2d and D6h) for hydrogen storage including adsorption and encapsulation of hydrogen molecules. We find that silsesquioxane cages have up to about 4150 m2/g specific surface area (SSA) and 7.81 wt % for hydrogen storage. These calculated values are comparable to the highest hydrogen storage values of metal-organic frameworks, porous polymer networks, and covalent organic frameworks. In addition, we use the quasi-dynamic method to study the encapsulation of hydrogen molecules into these cages because of the timescale limitation of ab initio molecular dynamics. Thermodynamic parameters such as enthalpy and Gibbs free energy at different temperatures are calculated during the insertion processes. We find that the insertion process of a hydrogen molecule into the T12 (D6h) cage is almost energy-conserved and its energy barriers of enthalpy and free energy are moderate under standard conditions.  Copyright © 2020 American Chemical Society.",We find that silsesquioxane cages have up to about 4150 m2/g specific surface area (SSA) and 7.81 wt % for hydrogen storage. Thermodynamic parameters such as enthalpy and Gibbs free energy at different temperatures are calculated during the insertion processes.,_
!264,"We performed feasibility analysis of 10 kW hydrogen backup power system (H2BS) consisting of a water electrolyzer, a metal hydride hydrogen storage and a fuel cell. Capital investments in H2BS are mostly determined by the costs of the PEM electrolyzer, the fuel cell and solid state hydrogen storage materials, for single unit or small series manufacture the cost of AB5-type intermetallic compound can reach 50% of total system cost. Today the capital investments in H2BS are 3 times higher than in conventional lead-acid system of the same capacity. Wide distribution of fuel cell hydrogen vehicles, development of hydrogen infrastructure, and mass production of hydrogen power systems will for sure lower capital investments in fuel cell backup power. Operational expenditures for H2BS is only 15% from the expenditures for lead acid systems, and after 4-5 years of exploitation the total cost of ownership will become lower than for batteries. © Published under licence by IOP Publishing Ltd.","Capital investments in H2BS are mostly determined by the costs of the PEM electrolyzer, the fuel cell and solid state hydrogen storage materials, for single unit or small series manufacture the cost of AB5-type intermetallic compound can reach 50% of total system cost. Wide distribution of fuel cell hydrogen vehicles, development of hydrogen infrastructure, and mass production of hydrogen power systems will for sure lower capital investments in fuel cell backup power.",_
!265,"For sustainable and incremental growth, mankind is adopting renewable sources of energy along with storage systems. Storing surplus renewable energy in the form of hydrogen is a viable solution to meet continuous energy demands. In this paper the concept of electrochemical hydrogen storage in a solid multi-walled carbon nanotube (MWCNT) electrode integrated in a modified unitized regenerative fuel cell (URFC) is investigated. The method of solid electrode fabrication from MWCNT powder and egg white as an organic binder is disclosed. The electrochemical testing of a modified URFC with an integrated MWCNT-based hydrogen storage electrode is performed and reported. Galvanostatic charging and discharging was carried out and results analyzed to ascertain the electrochemical hydrogen storage capacity of the fabricated electrode. The electrochemical hydrogen storage capacity of the porous MWCNT electrode is found to be 2.47 wt%, which is comparable with commercially available AB5-based hydrogen storage canisters. The obtained results prove the technical feasibility of a modified URFC with an integrated MWCNT-based hydrogen storage electrode, which is the first of its kind. This is surelya step forward towards building a sustainable energy economy. © 2019 by the authors.",The method of solid electrode fabrication from MWCNT powder and egg white as an organic binder is disclosed. The electrochemical testing of a modified URFC with an integrated MWCNT-based hydrogen storage electrode is performed and reported.,_
!266,"Hydride-forming alloys are currently considered reliable and suitable hydrogen storage materials because of their relatively high volumetric densities, and reversible H2 absorption/desorption kinetics, with high storage capacity. Nonetheless, their practical use is obstructed by several factors, including deterioration and slow hydrogen absorption/desorption kinetics resulting from the surface chemical action of gas impurities. Lately, common strategies, such as spark plasma sintering, mechanical alloying, melt spinning, surface modification and alloying with other elements have been exploited, in order to overcome kinetic barriers. Through these techniques, improvements in hydriding kinetics has been achieved, however, it is still far from that required in practical application. In this review, we provide a critical overview on the effect of mechanical alloying of various metal hydrides (MHs), ranging from binary hydrides (CaH2, MgH2, etc) to ternary hydrides (examples being Ti-Mn-N and Ca-La-Mg-based systems), that are used in solid-state hydrogen storage, while we also deliver comparative study on how the aforementioned alloy preparation techniques affect H2 absorption/desorption kinetics of different MHs. Comparisons have been made on the resultant material phases attained by mechanical alloying with those of melt spinning and spark plasma sintering techniques. The reaction mechanism, surface modification techniques and hydrogen storage properties of these various MHs were discussed in detail. We also discussed the remaining challenges and proposed some suggestions to the emerging research of MHs. Based on the findings obtained in this review, the combination of two or more compatible techniques, e.g., synthesis of metal alloy materials through mechanical alloying followed by surface modification (metal deposition, metal-metal co-deposition or fluorination), may provide better hydriding kinetics. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.","Nonetheless, their practical use is obstructed by several factors, including deterioration and slow hydrogen absorption/desorption kinetics resulting from the surface chemical action of gas impurities. Comparisons have been made on the resultant material phases attained by mechanical alloying with those of melt spinning and spark plasma sintering techniques.",_
!267,"Ammine metal borohydrides show potential for solid-state hydrogen storage and can be tailored toward hydrogen release at low temperatures. Here, we report the synthesis and structural characterization of seven new ammine metal borohydrides, M(BH4)3·nNH3, M = La (n = 6, 4, or 3) or Ce (n = 6, 5, 4, or 3). The two compounds with n = 6 are isostructural and have new orthorhombic structure types (space group P21212) built from cationic complexes, [M(NH3)6(BH4)2]+, and are charge balanced by BH4-. The structure of Ce(BH4)3·5NH3 is orthorhombic (space group C2221) and is built from cationic complexes, [Ce(NH3)5(BH4)2]+, and charge balanced by BH4-. These are rare examples of borohydride complexes acting both as a ligand and as a counterion in the same compound. The structures of M(BH4)3·4NH3 are monoclinic (space group C2), built from neutral molecular complexes of [M(NH3)4(BH4)3]. The new compositions, M(BH4)3·3NH3 (M = La, Ce), among ammine metal borohydrides, are orthorhombic (space group Pna21), containing molecular complexes of [M(NH3)3(BH4)3]. A revised structural model for A(BH4)3·5NH3 (A = Y, Gd, Dy) is presented, and the previously reported composition A(BH4)3·4NH3 (A = Y, La, Gd, Dy) is proposed in fact to be M(BH4)3·3NH3 along with a new structural model. The temperature-dependent structural properties and decomposition are investigated by in situ synchrotron radiation powder X-ray diffraction in vacuum and argon atmosphere and by thermal analysis combined with mass spectrometry. The compounds with n = 6, 5, and 4 mainly release ammonia at low temperatures, while hydrogen evolution occurs for M(BH4)3·3NH3 (M = La, Ce). Gas-release temperatures and gas composition from these compounds depend on the physical conditions and on the relative stability of M(BH4)3·nNH3 and M(BH4)3 © 2020 American Chemical Society.","The two compounds with n = 6 are isostructural and have new orthorhombic structure types (space group P21212) built from cationic complexes, [M(NH3)6(BH4)2]+, and are charge balanced by BH4-. These are rare examples of borohydride complexes acting both as a ligand and as a counterion in the same compound.",_
!268,"An analysis to hydrogen storage technologies, with major focus on the solid-state hydrogen storage is presented. A discussion on the physicochemical and thermodynamic aspects of the metal hydride formation is introduced, and the most common metal hydride compounds are analyzed. The necessity for the development of an accurate numerical analysis to describe the storage/release of hydrogen in metal hydrides and the establishment of an effective heat management is also explained and discussed. © 2018 Elsevier Inc. All rights reserved.","An analysis to hydrogen storage technologies, with major focus on the solid-state hydrogen storage is presented. A discussion on the physicochemical and thermodynamic aspects of the metal hydride formation is introduced, and the most common metal hydride compounds are analyzed.",_
!269,"A new solid-state hydrogen storage system of magnesium hydride (MgH2) doped with 5 wt% of metallic glassy (MG) zirconium palladium (Zr2Pd) nanopowder was fabricated using a high-energy ball milling technique. The end-product obtained after 50 h of milling was consolidated into bulk buttons, using a hot-pressing technique at 350 °C. The results have shown that this consolidation step, followed by the repetitive pressing at ambient temperature did not affect the nanocrystalline characteristics of pressed powders. Recycling pressing demonstrated beneficial effects of plastic deformation and lattice imperfections on Mg, leading to its enhanced hydrogenation/dehydrogenation kinetics and cycle-life-time performance compared with untreated samples. The results elucidated that spherical, hard, nanopowder of MG-Zr2Pd were forced to penetrate the Mg/MgH2 matrix to create micro/nanopore structures upon pressing for 50 cycles. These ultrafine spherical metallic glassy particles (∼400 nm in diameter) acted as a micro-milling media for reducing the particle size of MgH2 powders into submicron particles. In addition, they played a vital role as grain growth inhibitors to prevent the undesired growth of Mg grains upon the application of a moderate temperature in the range of 50 °C to 350 °C. The apparent activation energy for the decomposition of this new consolidated nanocomposite material was measured to be 92.2 kJ mol-1, which is far below than the measured value of pure nanocrystalline MgH2 powders (151.2 kJ mol-1) prepared in the present study. This new binary system possessed superior hydrogenation kinetics, indicated by the rather low temperature (200 °C) required to uptake 6.08 wt% H2 within 7.5 min. More importantly, the system revealed excellent dehydrogenation kinetics at 225 °C as implied by the limited time needed to release 6.1 wt% H2 in 10 min. The MgH2/5 wt% MG-Zr2Pd system showed a high performance for cyclability, implied by the achievement of continuous cycles (338 cycles) at 225 °C without degradation over 227 h. This journal is © 2019 The Royal Society of Chemistry.","The end-product obtained after 50 h of milling was consolidated into bulk buttons, using a hot-pressing technique at 350 °C. This new binary system possessed superior hydrogenation kinetics, indicated by the rather low temperature (200 °C) required to uptake 6.08 wt% H2 within 7.5 min.",_
!270,"In the framework of the European project SSH2S, a solid-state hydrogen storage tank - fuel cell system was demonstrated as Auxiliary Power Unit (APU) for a light duty vehicle. In this work, we have assessed the environmental impacts and the costs of the system developed. Following an eco-design approach, we have identified the processes mostly contributing to them and we have suggested possible improvements. By performing a Life Cycle Assessment (LCA), we found that, when the electricity consumption for hydrogen gas compression is included into the analysis, a solid-state hydrogen storage tank has similar greenhouse gas emissions and primary energy demand than those of type III and IV tanks. However, the resources depletion is higher for the solid-state system, even though the inclusions of the end of life of the APU and the recycling of the materials may result in different conclusions. The costs of an APU equipped with a solid-state hydrogen storage tank are significantly higher, about 1.5–2 times the systems based on type III and IV tanks. However, mature technologies are compared with a prototype, which has much room for optimization. To improve both the environmental and economic performances of the APU, a reduction of structural materials for both the solid-state hydrogen tank and Balance of Plant is recommended. © 2018 Elsevier Ltd","By performing a Life Cycle Assessment (LCA), we found that, when the electricity consumption for hydrogen gas compression is included into the analysis, a solid-state hydrogen storage tank has similar greenhouse gas emissions and primary energy demand than those of type III and IV tanks. However, mature technologies are compared with a prototype, which has much room for optimization.",_
!271,"Hydrogen is a generally abundant, safe, clean and environmentally apt alternative fuel, which replenishes the void generated by depleting fossil fuel reserves. The adoption of hydrogen as an energy source has been restricted to low levels due to the complications associated with its viable storage and usage. Existing technologies, such as storage of hydrogen in compressed and liquefied forms are not adequate to meet the broad on-board applications. The gravimetric energy density (120 MJ/kg) of hydrogen is three times higher than that of gasoline products, so solid-state hydrogen storage is advantageous. Metal-organic frameworks (MOFs), multi-walled carbon nanotubes (MWCNTs) and graphene are solid adsorbents majorly employed for efficient H2 storage. The prominent features of MOFs such as permanent porosity, structural rigidity, and surface area are attractive and ideal for hydrogen storage. In addition, nanostructured carbon materials (MWCNTs and graphene) and their composites have demonstrated significant hydrogen storage capacities. Some important parameters for the success of the hydrogen economy include high storage density, adsorption/desorption temperature and cycling time. Cryo-hydrogen storage was achieved in MOFs and their composites with carbon structures, but storage at ambient temperature and acceptable pressures is a major hurdle. This review discusses various strategies and mechanisms in the design of adsorbents explored to improve H2 storage capacities and afford opportunities to develop new sustainable hydrogen technologies to meet energy targets. © 2018 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences","Existing technologies, such as storage of hydrogen in compressed and liquefied forms are not adequate to meet the broad on-board applications. Metal-organic frameworks (MOFs), multi-walled carbon nanotubes (MWCNTs) and graphene are solid adsorbents majorly employed for efficient H2 storage.",_
!272,"Abstract: This paper deals with hydrogen storage properties of Ti-V based BCC solid solution incorporated with Fe. The alloy with composition Ti2FeV was prepared by arc melting method. X-ray diffraction (XRD) and energy dispersive X-ray analysis studies confirmed formation of solid solution phase with uniform composition and BCC structure. SEM studies revealed the formation of irregular shaped particles with size in the range of few microns up on hydrogenation of the parent alloy. The alloy shows maximum hydrogen storage capacity of 3.41 wt.% at 20 bar and 303 K and the thermodynamic parameters established near room temperature suitability of the alloy for solid state hydrogen storage applications. Hydrogenation kinetics is found to be quite fast and detailed kinetic analysis were done to underscore the hydrogenation mechanism. Activation energy during the initial stage of hydrogenation is found to be 30.8 kJ/mol. The value decreases to 14.4 kJ/mol for extended duration of hydrogenation, and this is explained based on difference in rate determining steps existing at different time scales. Graphic abstract: Extent of hydrogen absorption as a function of temperature and time for Ti2FeV alloy.[Figure not available: see fulltext.] © 2019, Indian Academy of Sciences.","Activation energy during the initial stage of hydrogenation is found to be 30.8 kJ/mol. The value decreases to 14.4 kJ/mol for extended duration of hydrogenation, and this is explained based on difference in rate determining steps existing at different time scales.",_
!273,"A novel solid-solution MXene (Ti0.5V0.5)3C2 is successfully synthesized by exfoliating a solid-solution MAX phase (Ti0.5V0.5)3AlC2, and its catalytic effect on the hydrogen storage reaction of Mg is systemically evaluated for the first time. Typical layer morphology is observed for the prepared (Ti0.5V0.5)3C2, which exhibits a better catalytic activity than that of Ti3C2. The addition of 10 wt% (Ti0.5V0.5)3C2 remarkably reduces the dehydrogenation onset temperature of MgH2 by 70 °C, from 266 to 196 °C. At 250 °C, approximately 5.0 wt% H2 is released from the 10 wt% (Ti0.5V0.5)3C2-containing MgH2 within 20 min. The dehydrogenated sample rapidly absorbs 4.8 wt% H2 within 5 s at 120 °C; these hydrogenation kinetics are much more superior even to the well-studied Nb2O5 catalyst. The apparent activation energy is calculated to be 77.3 kJ/mol for the MgH2-10 wt% (Ti0.5V0.5)3C2 sample, which is only around half of that of the pristine MgH2 (153.8 kJ/mol). This is responsible for the remarkably reduced dehydrogenation operating temperature. Moreover, the chemical states of (Ti0.5V0.5)3C2 during dehydrogenation are also analysed and discussed. © 2018 Acta Materialia Inc.","A novel solid-solution MXene (Ti0.5V0.5)3C2 is successfully synthesized by exfoliating a solid-solution MAX phase (Ti0.5V0.5)3AlC2, and its catalytic effect on the hydrogen storage reaction of Mg is systemically evaluated for the first time. Typical layer morphology is observed for the prepared (Ti0.5V0.5)3C2, which exhibits a better catalytic activity than that of Ti3C2.",_
!274,"Two approaches of engineering surface structures of V-Ti-based solid solution hydrogen storage alloys are presented, which enable improved tolerance toward gaseous oxygen (O2) impurities in hydrogen (H2) gas. Surface modification is achieved through engineering lanthanum (La)- or nickel (Ni)-rich surface layers with enhanced cyclic stability in an H2/O2 mixture. The formation of a Ni-rich surface layer does not improve the cycling stability in H2/O2 mixtures. Mischmetal (Mm, a mixture of La and Ce) agglomerates are observed within the bulk and surface of the alloy when small amounts of this material are added during arc melting synthesis. These agglomerates provide hydrogen-transparent diffusion pathways into the bulk of the V-Ti-Cr-Fe hydrogen storage alloy when the remaining oxidized surface is already nontransparent for hydrogen. Thus, the cycling stability of the alloy is improved in an O2-containing hydrogen environment as compared to the same alloy without addition of Mm. The obtained surface-engineered storage material still absorbs hydrogen after 20 cycles in a hydrogen-oxygen mixture, while the original material is already deactivated after 4 cycles. © 2017 American Chemical Society.","Two approaches of engineering surface structures of V-Ti-based solid solution hydrogen storage alloys are presented, which enable improved tolerance toward gaseous oxygen (O2) impurities in hydrogen (H2) gas. The obtained surface-engineered storage material still absorbs hydrogen after 20 cycles in a hydrogen-oxygen mixture, while the original material is already deactivated after 4 cycles.",_
!275,"Magnesium borohydride (Mg(BH4)2) is a promising material for solid state hydrogen storage. However, the predicted reversible hydrogen sorption properties at moderate temperatures have not been reached due to sluggish hydrogen sorption kinetics. Hydrogen (H) → deuterium (D) exchange experiments can contribute to the understanding of the stability of the BH4                             - anion. Pure γ-Mg(BH4)2, ball milled Mg(BH4)2 and composites with the additives nickel triboride (Ni3B) and diniobium pentaoxide (Nb2O5) have been investigated. In situ Raman analysis demonstrated that in pure γ-Mg(BH4)2 the isotopic exchange reaction during continuous heating started at ∼80 °C, while the ball milled sample did not show any exchange at 3 bar D2. However, during ex situ exchange reactions investigated by infrared (IR) and thermogravimetric (TG) analyses a comparable H → D exchange during long exposures (23 h) to deuterium atmosphere was observed for as received, ball milled and γ-Mg(BH4)2 + Nb2O5, while the Ni3B additive hindered isotopic exchange. The specific surface areas (SSA) were shown to be very different for as received γ-Mg(BH4)2, BET area = 900 m2 g-1, and ball milled Mg(BH4)2, BET area = 30 m2 g-1, respectively, and this explains why no gas-solid H(D) diffusion was observed for the ball milled (amorphous) Mg(BH4)2 during the short time frames of in situ Raman measurements. The heat treated ball milled sample partially regained the porous γ-Mg(BH4)2 structure (BET area = 560 m2 g-1). This in combination with the long reaction times allowing for the reaction to approach equilibrium explains the observed gas-solid H(D) diffusion during long exposure. We have also demonstrated that a small amount of D can be substituted in both high surface area and low surface area samples at room temperature proving that the B-H bonds in Mg(BH4)2 can be challenged at these mild conditions. © 2018 The Royal Society of Chemistry.","The specific surface areas (SSA) were shown to be very different for as received γ-Mg(BH4)2, BET area = 900 m2 g-1, and ball milled Mg(BH4)2, BET area = 30 m2 g-1, respectively, and this explains why no gas-solid H(D) diffusion was observed for the ball milled (amorphous) Mg(BH4)2 during the short time frames of in situ Raman measurements. We have also demonstrated that a small amount of D can be substituted in both high surface area and low surface area samples at room temperature proving that the B-H bonds in Mg(BH4)2 can be challenged at these mild conditions.",_
!276,"Nowadays energy storage seems to be a vital point in any new energy paradigm. It has become an important and strategic issue, to ensure the energetic sufficiency of humanity. Indeed, hydrogen storage in solids has been proved and revealed as clean and efficient energy storage. Moreover, it can be thought as a seriously considered solution to enable renewable energy to be a part of our quotidian life. To achieve storing hydrogen in solid form, the present study aimed to concepts and simulates a solid-state hydrogen storage reactor (tank). An investigation of the parameters influencing the hydrogen storage performance is carried out. Meanwhile, to understand the physical phenomenon taking place during the storage of hydrogen, a 2D numerical modelling for a metal hydrides-based in hydrogen reactor is presented. A strong coupling between energy balance, kinetic law, as well as a mass momentum balance at sorbent bed temperature under a non-uniform pressure was resolved based on finite element method. The temporal evolutions of pressure, the raising temperature in the bed during the hydriding process as well as the impact of the hydrogen supply pressure within the tank are analysed and validated by comparison with the experimental work in literature, a good agreement is obtained. From an industrial point of view, this study can be used to design and manufacture an optimal solid-state hydrogen storage reactor. © EDP Sciences, 2019.","It has become an important and strategic issue, to ensure the energetic sufficiency of humanity. Meanwhile, to understand the physical phenomenon taking place during the storage of hydrogen, a 2D numerical modelling for a metal hydrides-based in hydrogen reactor is presented.",_
!277,"Magnesium hydride has been seen as a potential material for solid state hydrogen storage, but the kinetics and thermodynamics obstacles have hindered its development and application. Three-dimensional flower-like TiO2@C and TiO2 were synthesized as the catalyst for MgH2 system and great catalytic activities are acquired in the hydrogen sorption properties. Experiments also show that the flower-like TiO2@C is superior to flower-like TiO2 in improving the hydrogen storage properties of MgH2. The hydrogen desorption onset and peak temperatures of flower-like TiO2 doped MgH2 is reduced to 199.2 °C and 245.4 °C, while the primitive MgH2 starts to release hydrogen at 294.6 °C and the rapid dehydrogenation temperature is even as high as 362.6 °C. The onset and peak temperatures of flower-like TiO2@C doped MgH2 are further reduced to 180.3 °C and 233.0 °C. The flower-like TiO2@C doped MgH2 composite can release 6.0 wt% hydrogen at 250 °C within 7 min, and 4.86 wt% hydrogen at 225 °C within 60 min, while flower-like TiO2 doped MgH2 can release 6.0 wt% hydrogen at 250 °C within 8 min, and 3.89 wt% hydrogen at 225 °C within 60 min. Hydrogen absorption kinetics is also improved dramatically. Moreover, compared with primitive MgH2 and the flower-like TiO2 doped MgH2, the activation energy of flower-like TiO2@C doped MgH2 is significantly decreased to 67.10 kJ/mol. All the improvement of hydrogen sorption properties can be ascribed to the flower-like structure and the two-phase coexistence of TiO2 and amorphous carbon. Such phase composition and unique structure are proved to be the critical factor to improve the hydrogen sorption properties of MgH2, which can be considered as the new prospect for improving the kinetics of light-metal hydrogen storage materials. © 2019","Magnesium hydride has been seen as a potential material for solid state hydrogen storage, but the kinetics and thermodynamics obstacles have hindered its development and application. Three-dimensional flower-like TiO2@C and TiO2 were synthesized as the catalyst for MgH2 system and great catalytic activities are acquired in the hydrogen sorption properties.",_
!278,"                             Magnesium hydride (MgH                             2                             ) has been considered to be one of the most promising solid-state hydrogen storage materials owing to its high hydrogen capacities, excellent reversibility and abundant source. However, the high dehydrogenation energy barrier and poor kinetics embarrass the practical application of MgH                             2                              in fuel cell. Doping nano-catalyst is deemed to be the most effective method to improve kinetics property of hydrogen storage materials, but the nanoparticles generally suffer from agglomeration and inactivation during the cycling hydrogen storage. Here we present a promising strategy to facilely prepare a high-efficiency transition metal oxide nano-catalyst, TiO                             2                              nanoparticles, in which monodispersed single-crystal-like TiO                             2                              nanoparticles are wrapped with amorphous carbon. The in-situ synthesized TiO                             2                              nanoparticles/amorphous carbon catalyst exhibit superior catalytic effect on the dehydrogenation properties of MgH                             2                             . A significant reductions of hydrogen desorption temperature (163.5 °C) and activation energy (69.2 kJ mol                             −1                             ) have been obtained for the TiO                             2                              nanoparticles/amorphous carbon catalyzed MgH                             2                             , which can be fully rehydrogenated with a reversible capacity of about 6.5 wt% at 200 °C within 5 min, and then completely dehydrogenated at 275 °C within 10 min. It is demonstrated that such significantly improved hydrogen desorption properties can be attributed to the in-situ formation of TiO                             2                              nanoparticles, amorphous carbon and multi-valance Ti species, which play the synergistically catalytic roles in the nano-catalyst. In particular, the presence of amorphous carbon in the catalyst can not only prevent the aggregation and growth of catalyst nanoparticles, but also dramatically reduce the desorption energy value of H in MgH                             2                             , according to the density functional theory calculation. This finding opens a new venue for the synthesis of monodispersed single-crystal-like TiO                             2                              nanoparticles/amorphous carbon catalyst with high-activity, safety, low cost, and its practical application in MgH                             2                              and other hydrogen storage systems.                          © 2019 Elsevier Ltd","A significant reductions of hydrogen desorption temperature (163.5 °C) and activation energy (69.2 kJ mol                             −1                             ) have been obtained for the TiO                             2                              nanoparticles/amorphous carbon catalyzed MgH                             2                             , which can be fully rehydrogenated with a reversible capacity of about 6.5 wt% at 200 °C within 5 min, and then completely dehydrogenated at 275 °C within 10 min. This finding opens a new venue for the synthesis of monodispersed single-crystal-like TiO                             2                              nanoparticles/amorphous carbon catalyst with high-activity, safety, low cost, and its practical application in MgH                             2                              and other hydrogen storage systems.",_
!279,"As an ideal secondary energy source, hydrogen energy has attracted the attention of researchers in the world in order to solve the problems of environment pollution and energy shortage. The solid-state hydrogen storage possessing high energy storage density and good safety is regarded as the most promising way among many hydrogen storage methods. Hydrogen storage materials composed of light elements (such as metal hydrides, borohydrides, aluminum hydrides, amino hydrides, ammonia borane) have become a research hotspot in the field of hydrogen storage owning to their high energy storage density. From the perspective of thermodynamics, this manuscript reviews recent progresses of several light hydrogen storage materials, especially the modification of materials. What's more, the development trend of light hydrogen storage materials is prospected. © 2019 Scientia Sinica Chimica. All rights reserved.","Hydrogen storage materials composed of light elements (such as metal hydrides, borohydrides, aluminum hydrides, amino hydrides, ammonia borane) have become a research hotspot in the field of hydrogen storage owning to their high energy storage density. What's more, the development trend of light hydrogen storage materials is prospected.",_
!280,"MgH2 doped with transition metal halides (TiF4, NbF5, and ZrCl4) and activated carbon nanofibers (ACNF) for reversible hydrogen storage is prepared by ball milling technique. Transition metal halides provide catalytic effects for de/rehydrogenation kinetics, while ACNF benefits thermal conductivity and hydrogen permeability as well as prevents particle agglomeration during cycling. Significant reduction of onset and main dehydrogenation temperatures of MgH2 (ΔT = 243 and 158 °C, respectively) are achieved by doping with 5–10 wt % of NbF5, ACNF-TiF4 and ACNF-NbF5. During the 1st cycle, the latter samples liberate 4.7–5.0 wt % H2 within 1 h 30 min, whereas MgH2 doped with ACNF reaches only 1.5 wt % H2. The reaction between MgF2 and NbHx (x < 1) (MgH2-NbF5 and MgH2-ACNF-NbF5) during dehydrogenation results in the formation of new catalytic active species of Nb-F-Mg favoring kinetics. Upon four hydrogen release and uptake cycles, kinetics and reversibility within 1 h 30 min of MgH2-ACNF-NbF5 are preserved at 5.0 wt % H2, while those of MgH2-NbF5 and MgH2-ACNF-TiF4 decay to 4.4 wt % H2. Activation energy (EA) for dehydrogenation of MgH2 considerably decreases from 140.0 ± 10.2 to 37.8 ± 1.5 kJ/mol after doing with ACNF-NbF5. Superior performance of MgH2-ACNF-NbF5 to MgH2-NbF5 is due to synergistic effects of NbF5 and ACNF. In the case of MH2-ACNF-TiF4, the disappearance of active species benefiting kinetic properties and the formation of thermally stable TiH2 account for inferior hydrogen content reversible. © 2018 Elsevier Ltd","Transition metal halides provide catalytic effects for de/rehydrogenation kinetics, while ACNF benefits thermal conductivity and hydrogen permeability as well as prevents particle agglomeration during cycling. Activation energy (EA) for dehydrogenation of MgH2 considerably decreases from 140.0 ± 10.2 to 37.8 ± 1.5 kJ/mol after doing with ACNF-NbF5.",_
!281,"Understanding diffusion of large solutes such as hydrogen and lithium in solids is of paramount importance for energy storage in metal hydrides and advanced batteries. Due to its high gravimetric and volumetric densities, magnesium is a material of great potential for solid-state hydrogen storage. However, the slow hydrogen diffusion kinetics and the deleterious blocking effect in magnesium have hampered its practical applications. Here, we demonstrate fast lateral hydrogen diffusion in quasifree magnesium films without the blocking effect. Massive concomitant lattice expansion leads to the formation of remarkable self-organized finger patterns extending over tens of micrometers. Detailed visualization of diffusion fronts reveals that the fingers in these patterns follow locally the direction of hydrogen diffusion. Thus, the streamlines of the diffusion process are self-recorded by means of the finger pattern. By inclusion of fast hydrogen diffusion objects or local gaps, the resulting streamlines exhibit a clear analogy to optical rays in geometric optics. The possibility to spatially manipulate hydrogen diffusion opens an avenue to build advanced hydrogen storage systems, cloaking and active plasmonic devices, as well as prototype systems for computational models. © 2018 American Physical Society.","Due to its high gravimetric and volumetric densities, magnesium is a material of great potential for solid-state hydrogen storage. By inclusion of fast hydrogen diffusion objects or local gaps, the resulting streamlines exhibit a clear analogy to optical rays in geometric optics.",_
!282,"Ammonia is well-known as a hydrogen carrier owing to its high hydrogen capacity (17.8 wt %). However, the toxicity and the high storage pressure limit the application of ammonia. Consequently, storing ammonia in solid state has become the promising method to utilize ammonia for practical applications. In this review, ammonia absorption properties of metal hydrides, halides, and borohydrides to form metal amides and metal ammine complexes with various coordination numbers have been systematically summarized. Through this research, we found the correlation between the reactivity with ammonia and the Pauling electronegativity of neutral atoms according to different systems. Metal hydrides with small electronegativity value of the neutral atom of the cations can react with ammonia to form metal amides, which can be used as hydrogen storage material. For metal halides or borohydrides, the lower plateau pressure of ammonia absorption can be obtained in the material with larger electronegativity value of the neutral atom of cations. This useful tendency can be used in the materials design for the potential applications of ammonia-fed fuel cells. © 2018 American Chemical Society.","Metal hydrides with small electronegativity value of the neutral atom of the cations can react with ammonia to form metal amides, which can be used as hydrogen storage material. This useful tendency can be used in the materials design for the potential applications of ammonia-fed fuel cells.",_
!283,"Firstly, the hydrogen storage materials for solid-state hydrogen storage are defined and summarized. Then, current research progress is summarized by comparing the mechanism, advantages and disadvantages of the hydrogen storage materials, and the future development trend of hydrogen storage materials is prospected. © 2019, China National Chemical Information Center. All right reserved.","Firstly, the hydrogen storage materials for solid-state hydrogen storage are defined and summarized. Then, current research progress is summarized by comparing the mechanism, advantages and disadvantages of the hydrogen storage materials, and the future development trend of hydrogen storage materials is prospected.",_
!284,"Solid-state hydrogen storage is of considerable concern as a potential hydrogen source for portable fuel cell applications. This study mainly focuses on kinetics of NaBH4/Al2O3 nanoparticles (20 nm)/H2O system with CoCl2 as catalyst and the factors that affect the hydrogen generation rate (HGR). It is observed that the reaction rate increases considerably with increase in NaBH4, Al2O3 nanoparticle (20 nm), CoCl2 and NaOH concentrations and the respective reaction orders are calculated. Hydrogen generation rate is also investigated at different temperatures (303, 313, 323 and 333 K) for constant NaBH4 (1.25 moles/L), NaOH (1.4 moles/L), CoCl2 (0.02 moles/L) and Al2O3 (0.09 moles/L) concentrations. Kinetics of the NaBH4 hydrolysis reaction increases with ?-Al2O3 nanoparticles and the calculated activation energy is 29 kJ/moles. This study also reports that a combined dual-solid-fuel system is highly efficient in terms of hydrogen storage capacities compared with a single hydride based system. Maximum hydrogen generation efficiency, observed at a mass ratio of 0.09: 0.7 (Al2O3/NaBH4), is 99.34%. © 2019 Assoc. Brasiliera de Eng. Quimica / Braz. Soc. Chem. Eng.. All rights reserved.","This study also reports that a combined dual-solid-fuel system is highly efficient in terms of hydrogen storage capacities compared with a single hydride based system. Maximum hydrogen generation efficiency, observed at a mass ratio of 0.09: 0.7 (Al2O3/NaBH4), is 99.34%.",_
!285,"In this study, a novel set of comprehensive arithmetic correlations has been proposed to design an industrial scale cylindrical reactor with embedded cooling tubes (ECT) for metal hydride (MH) based hydrogen storage and thermal management applications. Based on ASME standards, different nominal pipe sizes were imparted into a cylindrical reactor design with ECT to accommodate 50 kg of LaNi4.7Al0.3 alloy. A three dimensional numerical model has been developed using COMSOL Multiphysics 4.3a to predict the hydriding performance of designed reactors, which was further experimentally validated as well. At an absorption condition of 30 bar supply pressure and 298 K absorption temperature with 60 lpm volumetric HTF flow rate, 6 inch reactor with 99 ECT portrayed better heat transfer characteristics. From the parametric investigation, it is observed that the variation of supply pressure has predominant effect followed by the variation of the HTF flow rate on hydriding (absorption) kinetics of the device. However, the variation of absorption temperature has minuscule influence on the hydriding performance. At a supply condition of 30 bar and 298 K with water flow rate of 30 lpm, a hydrogen storage capacity (HSC) of 1.29 wt% was achieved within 2060 s. © 2019 Hydrogen Energy Publications LLC","In this study, a novel set of comprehensive arithmetic correlations has been proposed to design an industrial scale cylindrical reactor with embedded cooling tubes (ECT) for metal hydride (MH) based hydrogen storage and thermal management applications. A three dimensional numerical model has been developed using COMSOL Multiphysics 4.3a to predict the hydriding performance of designed reactors, which was further experimentally validated as well.",_
!286,"Nanomaterials may help to solve issues such as water availability, clean energy generation, control of drug-resistant microorganisms and food safety. Here we review innovative approaches to solve these issues using nanotechnology. The major topics discussed are wastewater treatment using carbon-based, metal-based and polymeric nanoadsorbents for removing organic and metal contaminants; nanophotocatalysis for microbial control; desalination of seawater using nanomembranes; energy conversion and storage using solar cells and hydrogen-sorbents nanostructures; antimicrobial properties of nanomaterials; smart delivery systems; biocompatible nanomaterials such as nanolignocellulosis and starches-based materials, and methods to decrease the toxicity of nanomaterials. Significantly, here it is reviewed two ways to palliate nanomaterials toxicity: (a) controlling physicochemical factors affecting this toxicity in order to dispose of more safe nanomaterials, and (b) harnessing greener synthesis of them to bring down the environmental impact of toxic reagents, wastes and byproducts. All these current challenges are reviewed at the present article in an effort to evaluate environmental implications of nanomaterials technology by means of a complete, reliable and critical vision. © 2017, Springer International Publishing AG.","Nanomaterials may help to solve issues such as water availability, clean energy generation, control of drug-resistant microorganisms and food safety. All these current challenges are reviewed at the present article in an effort to evaluate environmental implications of nanomaterials technology by means of a complete, reliable and critical vision.",_
!287,"In an effort to realize a sustainable hydrogen economy, we are facing the demanding and challenging issue of providing compact and safe storage solutions for hydrogen in solid-state materials. Studies on the hydrogen storage properties of materials generally involve their phase structures, microstructures, thermal/structural stability, chemical compositions and bonding, which can be studied by ex situ experimental technologies. However, the experimental results obtained from ex situ measurements may be contaminated during sample handling, and some important intermediate phases are too metastable/unstable to be detected. To overcome the drawbacks, in situ studies are carried out, leading to a large number of unprecedented advantages. In this review, recent advances regarding in situ measurement technologies for solid-state hydrogen storage materials are summarized, mainly focusing on metal hydrides and complex hydrides. The working principles together with the devices used for the in situ methods are briefly introduced. Afterwards, both the classic and recent advances regarding the in situ measurement technologies for metal hydrides and complex hydrides are comprehensively summarized and reviewed. In addition to highlighting the tremendous merits of the in situ methods and the relevant achievements in the field of hydrogen storage materials, the remaining challenges and trends of the emerging research are also discussed. © 2020 Elsevier Ltd","In an effort to realize a sustainable hydrogen economy, we are facing the demanding and challenging issue of providing compact and safe storage solutions for hydrogen in solid-state materials. Studies on the hydrogen storage properties of materials generally involve their phase structures, microstructures, thermal/structural stability, chemical compositions and bonding, which can be studied by ex situ experimental technologies.",_
!288,"Magnesium borohydride (Mg(BH4)2) is an attractive materials for solid-state hydrogen storage due to its high hydrogen content (14.9 wt%). In the present work, the dehydrogenation performance of Mg(BH4)2 by adding different amounts (10, 20, 40, 60 wt%) of two-dimensional layered Ti3C2 MXene is studied. The Mg(BH4)2-40 wt% Ti3C2 composite releases 7.5 wt% hydrogen at 260 °C, whereas the pristine Mg(BH4)2 only releases 2.9 wt% hydrogen under identical conditions, and the onset desorption temperature decreases from 210 °C to a relative lower temperature of 82 °C. The special layered structure of Ti3C2 MXene and fluorine plays an important role in dehydrogenation process especially at temperatures below 200 °C. The main dehydrogenation reaction is divided into two steps, and activation energy of the Mg(BH4)2-40 wt% Ti3C2 composite is 151.3 kJ mol−1 and 178.0 kJ mol−1, respectively, which is much lower than that of pure Mg(BH4)2. © 2020 Hydrogen Energy Publications LLC","The Mg(BH4)2-40 wt% Ti3C2 composite releases 7.5 wt% hydrogen at 260 °C, whereas the pristine Mg(BH4)2 only releases 2.9 wt% hydrogen under identical conditions, and the onset desorption temperature decreases from 210 °C to a relative lower temperature of 82 °C. The special layered structure of Ti3C2 MXene and fluorine plays an important role in dehydrogenation process especially at temperatures below 200 °C.",_
!289,"A systematic calculation has been performed in order to study phase transitions and hydrogen storage properties of ternary hydride Li2MgH4 under pressure. The structural, elastic, electronic and vibrational properties of Li2MgH4 are collected by means of density functional theory. There are three phases identified; Pbam at 0 GPa, Pnma at 5 GPa and Pna21 at 65 GPa Pbam and Pnma phases of Li2MgH4 are found to be mechanically and dynamically stable. Ductility of the phases are determined based on Pugh's criteria. It is found that Li2MgH4 becomes ductile at 5 GPa, otherwise it is a brittle material. Electronic band structures and corresponding partial density of states of phases are also obtained. All phases at 0 GPa, 5 GPa and 65 GPa have wide band gaps, indicating that Li2MgH4 is an insulator at all pressures. The phonon dispersion curves of Pbam and Pnma phases have no imaginary frequency indicating that both phases of Li2MgH4 are dynamically stable. The gravimetric hydrogen density of Li2MgH4 is calculated as 10.52 wt %, which is a great rate along with the hydrogen desorption temperature of 670 K. © 2019 Hydrogen Energy Publications LLC",A systematic calculation has been performed in order to study phase transitions and hydrogen storage properties of ternary hydride Li2MgH4 under pressure. Ductility of the phases are determined based on Pugh's criteria.,_
!290,"Hydrogen is an ideal candidate to fuel as “future energy needs”. Hydrogen is a light (Mw = 2.016 g mol−1), abundant, and nonpolluting gas. Hydrogen as a fuel can be a promising alternative to fossil fuels; i.e., it enables energy security and takes cares of climate change issue. Hydrogen has a low density of around 0.0899 kg m−3 at normal temperature, and pressure (~7% of the density of air), which is the main challenge in its real applications. It means, for example, 1 kg of hydrogen requires an extremely high volume of around 11 m3. In order to solve this limitation of hydrogen, solid-state hydrogen storage materials are used to store hydrogen efficiently and effectively. In this chapter, an attempt has been developed to provide a comprehensive overview of the recent advances in hydrogen storage materials in terms of capacity, content, efficiency, and mechanism of storage. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd 2020.","Hydrogen is an ideal candidate to fuel as “future energy needs”. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd 2020.",_
!291,"The hydrogen economy is a proposed system where hydrogen is produced and used extensively as the primary energy carrier. Successful development of hydrogen economy means innumerable advantages for the environment, energy security, economy, and final users. One major key to wholly develop hydrogen economy is safe, compact, light and cost-efficient hydrogen storage. The conventional gaseous state storage system as pressurized hydrogen gas and liquid state storage system pose safety and cost problems to onboard applications; therefore, they do not satisfy the future goals for a hydrogen economy. Fortunately, solid-state storage systems based on metal hydrides have demonstrated great potentials to store hydrogen in large quantities in a quite secure, compact, and repeatedly reversible manner and thus, becoming increasingly attractive option for hydrogen applications. However, techno-economic feasibility of hydrogen storage systems is yet to be realized as none of the current metal hydrides fulfill all the essential criteria for a practical hydrogen economy, mainly because of low hydrogen storage capacity, sluggish kinetics and unacceptable temperatures of hydrogen absorption/desorption. This article gives a brief review of hydrogen as an ideal sustainable energy carrier for the future economy, its storage as the stumbling block as well as the current position of solid-state hydrogen storage in metal hydrides and makes a recommendation based on the most promising novel discoveries made in the field in recent times which suggests a prospective breakthrough towards a hydrogen economy. © 2019 Hydrogen Energy Publications LLC","The conventional gaseous state storage system as pressurized hydrogen gas and liquid state storage system pose safety and cost problems to onboard applications; therefore, they do not satisfy the future goals for a hydrogen economy. Fortunately, solid-state storage systems based on metal hydrides have demonstrated great potentials to store hydrogen in large quantities in a quite secure, compact, and repeatedly reversible manner and thus, becoming increasingly attractive option for hydrogen applications.",_
!292,"Mg-based hydrogen storage materials are considered to be one of the most promising solid-state hydrogen storage materials due to their large hydrogen storage capacity and low cost. However, slow hydrogen absorption/desorption rate and excessive hydrogen absorption/desorption temperature limit the application of Mg-based hydrogen storage materials. The present paper reviews the advances in the research of Mg-based hydrogen storage film in recent years, including the advantage of the film, the function theory of fabricating method and its functional theory, and the influencing factors in the technological process. The research status worldwide is introduced in detail. By comparing pure Mg, Pd-caped Mg, non-palladium capped Mg, and Mg alloy hydrogen storage films, an ideal tendency for producing Mg-based film is pointed out, for example, looking for a cheap metal element to replace the high-priced Pd, compositing Mg film with other hydrogen storage alloy of catalytic elements, and so on. © 2019 Chinese Physical Society and IOP Publishing Ltd.","The research status worldwide is introduced in detail. By comparing pure Mg, Pd-caped Mg, non-palladium capped Mg, and Mg alloy hydrogen storage films, an ideal tendency for producing Mg-based film is pointed out, for example, looking for a cheap metal element to replace the high-priced Pd, compositing Mg film with other hydrogen storage alloy of catalytic elements, and so on.",_
!293,"Given the fact that lithium aluminum hydride (LiAlH4) can exist in distinct crystalline structures under different conditions, in this study, we aim to theoretically investigate the structural properties and the pressure-induced phase transformations of its 13 closely related crystal structures by means of the density functional theory (DFT). The present study reveals that the phase transformation of LiAlH4 from the most stable form (α-phase) to the second most stable form (-phase) occurs at approximately 3.3 GPa, corresponding to a volume collapse of ∼14% and a reduction of 22% in the crystal volume. Due to the relatively higher hydrogen weight content, -LiAlH4 becomes a potentially attractive candidate for solid-state hydrogen storage at moderate pressures. The two most stable forms, i.e., the structures with the (i) P21/c (α-LiAlH4) and (ii) I41/a (-LiAlH4) space groups, have been selected so that their structural and electronic properties can be discussed in greater detail. Our study also shows that the numerical results are greatly influenced by the choice of the DFT methods used, such as the exchange-correlation functionals and optimization schemes. © 2020 Author(s).","Given the fact that lithium aluminum hydride (LiAlH4) can exist in distinct crystalline structures under different conditions, in this study, we aim to theoretically investigate the structural properties and the pressure-induced phase transformations of its 13 closely related crystal structures by means of the density functional theory (DFT). Due to the relatively higher hydrogen weight content, -LiAlH4 becomes a potentially attractive candidate for solid-state hydrogen storage at moderate pressures.",_
!294,"Zr(BH4)4·8NH3 is considered to be a promising solid state hydrogen-storage material, due to its high hydrogen capacity and low dehydrogenation temperature. However, the possible applications of Zr(BH4)4·8NH3 have been greatly hampered by the complicated and less applicable synthesis process, which must be operated at relatively low temperature (<20 °C). Herein, we reported a simple and facile “heating-(ball milling) BM vial” method via physical vapour deposition to tackle this issue. By this technique, Zr(BH4)4·8NH3 was successfully synthesized. Furthermore, composite formation by adding 10 wt% NaBH4 to the as-prepared Zr(BH4)4·8NH3 was found to be able to lower down the dehydrogenation peak of Zr(BH4)4·8NH3 from 130 to 75 °C and more excitingly, the possible emission of B2H6 and NH3 from dehydrogenation of only Zr(BH4)4·8NH3 was completely suppressed after addition of NaBH4. This research presents a new hydrogen-storage system based on Zr(BH4)4·8NH3+NaBH4 composite and it also implies a new development methodology of future hydrogen storage materials. © 2018 Hydrogen Energy Publications LLC","However, the possible applications of Zr(BH4)4·8NH3 have been greatly hampered by the complicated and less applicable synthesis process, which must be operated at relatively low temperature (<20 °C). Herein, we reported a simple and facile “heating-(ball milling) BM vial” method via physical vapour deposition to tackle this issue.",_
!295,"Hydrogen storage materials based on the stoichiometry Mg(Ni1-xMnx)2 have been synthesized by High Energy Ball Milling (HEBM) and studied as potential candidate materials for solid state hydrogen storage. The microstructures of the as-cast and the milled alloys were characterized by means of X-ray Powder Diffraction (XRD) and Scanning Electron Microscopy (SEM) both prior and after the hydrogenation process. The storage characteristics (Pressure-Composition-Temperature isotherms) and the sorption kinetics obtained by a commercial and automatically controlled Sievert-type apparatus. The X-ray results showed that the substitution of Mn over Ni could eliminate and inhibit the MgNi2 phase. The calculation of the average crystallite size showed that the increase of the amount of Mn can reduce the size at the early stages, but for Mn content higher than 0.25 the crystallite size increases, while the microstrain levels decreased monotonically. The hydrogenation and dehydrogenation measurements took place at several temperatures (150–200–250–300 °C). The results showed that the kinetics for both the hydrogenation and dehydrogenation can be fast for operation at temperatures between 250 and 300 °C, but for temperatures below 200 °C the hydrogenation process is very slow, and the dehydrogenation process cannot be achieved. © 2019 Elsevier Ltd",Hydrogen storage materials based on the stoichiometry Mg(Ni1-xMnx)2 have been synthesized by High Energy Ball Milling (HEBM) and studied as potential candidate materials for solid state hydrogen storage. The hydrogenation and dehydrogenation measurements took place at several temperatures (150–200–250–300 °C).,_
!296,"NaMgH3 has been considered to be a potential candidate for solid-state hydrogen storage due to its considerable hydrogen gravimetric (6.0 wt %) and volumetric (88.0 g/L) densities. Meanwhile, NaMgH3 possesses an outstanding theoretical thermal storage density of 2881 kJ/kg, which makes it one of the most promising thermal energy storage materials. However, the sluggish dehydrogenation kinetics of NaMgH3 embarrasses further practical application. Doping a nanosize Ti-based catalyst is treated to be one of the most effective methods to settle the poor dehydriding kinetics. In this work, different kinds of TiO2 catalysts, the 5 wt % TiO2 microparticle (MP) (100 nm), TiO2 nanoparticle (NP) (5-10 nm), and TiO2 nanotube (NT) (5-10 nm), were doped into NaMgH3 in the process of ball milling and heat treatment, which in situ formed Na0.46TiO2 significantly promoting the full hydrogen desorption kinetics of NaMgH3. Among all samples, the TiO2 NT-doped sample shows the best performance of which the onset decomposition temperature is reduced to 300 °C, and the first- and second-step decomposition peak temperatures are decreased to 346.3 and 355.8 °C, respectively. The TiO2 NT-doped sample desorbs approximately 3.4 wt % H2 at 350 °C within 10 min, while the pure NaMgH3 sample releases only 0.2 wt % H2 in 10 min. The significant improvement in both two decomposition reactions kinetics of NaMgH3 can be attributed to the tubular morphology of the TiO2 NT and the in situ formation of multivalence Ti species (Na0.46TiO2). These two reasons can change the kinetic models of NaMgH3 from A2 to R2 and further dramatically decrease the activation energies of first- and second-step decomposition reactions of NaMgH3 to 91.7 and 142.1 kJ/mol, respectively. In particular, the in situ formed Na0.46TiO2 can benefit the e- transfers among Na+, Mg2+, and H-, tremendously enhancing dehydrogenation properties. © 2019 American Chemical Society.","However, the sluggish dehydrogenation kinetics of NaMgH3 embarrasses further practical application. In this work, different kinds of TiO2 catalysts, the 5 wt % TiO2 microparticle (MP) (100 nm), TiO2 nanoparticle (NP) (5-10 nm), and TiO2 nanotube (NT) (5-10 nm), were doped into NaMgH3 in the process of ball milling and heat treatment, which in situ formed Na0.46TiO2 significantly promoting the full hydrogen desorption kinetics of NaMgH3.",_
!297,"A new and solvent-free synthesis route has been adopted and optimized to prepare crystalline VNbO5 from the mechanochemical reaction between Nb2O5 and V2O5 as starting reagents. The substantially amorphous mixture of equimolar pentoxide V and Nb metals observed after extended mechanical treatment transforms into a crystalline powder following calcination under mild conditions at 710 K. The structure solution of the X-ray diffraction pattern using a global optimization approach, combined with Rietveld refinement, points to a space group P212121 (no. 19) different from Pnma (no. 62) previously proposed in the literature assuming it to be isostructural to VTaO5. The new space group helps to describe weak peaks that remained previously unaccounted for and allows more reliable determination of atomic fractional coordinates and interatomic distance distribution. The as-prepared VNbO5 has been tested as a dopant (5 wt%) for the purpose of solid state hydrogen storage, decreasing significantly the release of hydrogen of MgH2/Mg (620 K) and further enhancing the hydrogen sorption kinetic properties. © The Royal Society of Chemistry 2019.","The substantially amorphous mixture of equimolar pentoxide V and Nb metals observed after extended mechanical treatment transforms into a crystalline powder following calcination under mild conditions at 710 K. The structure solution of the X-ray diffraction pattern using a global optimization approach, combined with Rietveld refinement, points to a space group P212121 (no. The new space group helps to describe weak peaks that remained previously unaccounted for and allows more reliable determination of atomic fractional coordinates and interatomic distance distribution.",_
!298,"A holistic approach is required for the development of materials and systems for hydrogen storage, embracing all the different steps involved in a successful advance of the technology. The several engineering solutions presented in this work try to address the technical challenges in synthesis and application of solid-state hydrogen storage materials, mainly metal hydride based compounds. Moving from the synthesis of samples in lab-scale to the production of industrial sized batches a novel process development is required, including safety approaches (for hazardous powders), and methods to prevent the contamination of sensitive chemicals. The reduction of overall costs has to be addressed as well, considering new sources for raw materials and more cost-efficient catalysts. The properties of the material itself influence the performances of the hydride in a pilot storage tank, but the characteristics of the system itself are crucial to investigate the reaction limiting steps and overcome hindrances. For this, critical experiments using test tanks are needed, learning how to avoid issues as material segregation or temperature gradients, and optimizing the design in the aspects of geometry, hull material, and test station facilities. The following step is a useful integration of the hydrogen storage system into real applications, with other components like fuel cells or hydrogen generators: these challenging scenarios provide insights to design new experiments and allow stimulating demonstrations. © 2018 Trans Tech Publications, Switzerland.","The reduction of overall costs has to be addressed as well, considering new sources for raw materials and more cost-efficient catalysts. The following step is a useful integration of the hydrogen storage system into real applications, with other components like fuel cells or hydrogen generators: these challenging scenarios provide insights to design new experiments and allow stimulating demonstrations.",_
!299,"Hydrogen energy is one of the most important choices for realizing clean energy because of its wide sources, no pollution, and high energy density. The technological innovation of fuel cells contributes to the attractive prospect of hydrogen energy in vehicles, but the problem of hydrogen filling and hydrogen storage has become one of the obstacles to the development of hydrogen energy cars. The safe and efficient hydrogen storage is crucial for the large-scale application of hydrogen energy. Till now there have been developed three main hydrogen storage methods, which include high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage and solid-state hydrogen storage. The gravimetric density of gaseous hydrogen storage system can be promoted by increasing the pressure of hydrogen and the specific strength of container material. However, H2 molecular interaction causes a relatively low volumetric density of gaseous hydrogen storage system, and excessively high hydrogen pressure challenges the safety and heightens design difficulty and cost of hydrogen tanks. The liquid hydrogen storage owns ideal gravimetric and volumetric density, which can be realized by compres-sing and liquefying hydrogen gas. However, liquid hydrogen is particularly prone to volatilize and liquid hydrogen container requires strict storing conditions. In addition, the liquefying process of gaseous hydrogen is uneconomical, as it consumes an energy quantity that constitutes about 40% of the combustion heat release of the stored hydrogen. For the solid-state hydrogen storage, hydrogen is stored in the hydrides in the form of atom or ion. Hence, the solid-state hydrogen storage obtains an impressively high volumetric density and enjoys greater security because the hydrogen storage materials absorb/desorb hydrogen at mild conditions. But the gravimetric density of hydrogen storage materials is comparatively low. The high-pressure hybrid hydrogen storage vessel, which combines the advantages of gaseous and solid-state hydrogen storage methods, offers a feasible path to safe and high-density hydrogen storage. The volumetric density of high-pressure hydrogen tank can be effectively enhanced by the hydrogen storage materials, resulting in lower operating pressure, smaller volume, and higher safety. The performance promotion of the high-pressure hybrid hydrogen storage vessels depends upon the development of materials with excellent hydrogen sorption performances under high hydrogen pressure. The AB2 type ZrFe2-based and TiCr2 based alloys are the currently prevailing high-pressure hydrogen storage materials. Though researchers mainly concentrate on and have achieved the regulation of storage capacity, absorption/desorption pressure plateau and kinetics through the alloying trials which partially substitute elements with various atomic radius and electronic structures for either A-site or B-site, the gravimetric densities of ZrFe2-based and TiCr2-based alloys are still unsatisfactory. NaAlH4 and AlH3 display considerable potential as candidate storage materials owing to their intrinsically high storage density. For NaAlH4, sufficient works have preliminarily confirmed the effectiveness of nanosizing and catalyst-doping toward dehydrogenation temperature reduction and cyclic stability enhancement. And the yield of AlH3 along with its crystallinity can likely be enhanced by adopting ball milling or improving the solvent. This review starts with a brief introduction of how the high-pressure hybrid hydrogen storage vessel works and a summary of the performance requirements of the hydrogen storage materials. It then provides detailed discussion and description upon the structure, characteristics and research status quo with respect to the above-mentioned two species of high-pressure hydrogen storage materials, i.e.hydrogen storage alloys (ZrFe2, TiCr2) and aluminum based complex hydrides (NaAlH4, AlH3). © 2019, Materials Review Magazine. All right reserved.","But the gravimetric density of hydrogen storage materials is comparatively low. The volumetric density of high-pressure hydrogen tank can be effectively enhanced by the hydrogen storage materials, resulting in lower operating pressure, smaller volume, and higher safety.",_
!300,"In solid-state hydrogen storage in light metal hydrides, nanoconfinement and the use of catalysts represent promising solutions to overcoming limitations such as poor reversibility and slow kinetics. In this work, the morphology and hydrogen desorption kinetics of NaAlH4 melt-infiltrated into a previously developed Ti-based doped porous Al scaffold is analysed. Small-angle X-ray scattering and scanning electron microscopy analysis of low NaAlH4 loading in the porous Al scaffold has revealed that mesopores and small macropores are filled first, leaving the larger macropores/voids empty. Temperature-programmed desorption experiments have shown that NaAlH4-infiltrated porous Al scaffolds show a higher relative H2 release, with respect to NaAlH4 + TiCl3, in the temperature range 148–220 °C, with the temperature of H2 desorption trending to bulk NaAlH4 with increasing scaffold loading. The Ti-based catalytic effect is reproduced when the dopant is present in the scaffold. Further work is required to increase the mesoporous volume in order to enhance the nanoconfinement effect. © 2018 Hydrogen Energy Publications LLC","In this work, the morphology and hydrogen desorption kinetics of NaAlH4 melt-infiltrated into a previously developed Ti-based doped porous Al scaffold is analysed. Small-angle X-ray scattering and scanning electron microscopy analysis of low NaAlH4 loading in the porous Al scaffold has revealed that mesopores and small macropores are filled first, leaving the larger macropores/voids empty.",_
!301,"In the field of the solid state hydrogen-storage materials, boron-ammine compounds appears excellent dehydrogenation properties. But the key problems are centering on the circulation of hydrogenation and controllable dehydrogenation. However, maybe it's a huge improvement if we introduce the Frustrated Lewis Pairs (FLPs) such as Carbon-Phosphorous bonds into the hydrogen-storage compounds. Presently, we design 7 compounds containing FLPs structures and 14 pathways of (de)hydrogenation based on the experiments and compare their properties of hydrogenation kinetically and thermodynamically. The results suggest the hydrogenation is direct related to the difference between the two relevant atomic charges. It's easy to be hydrogenation between the atoms with small change of the atomic charges after the additive reaction. © 2016 Hydrogen Energy Publications LLC","However, maybe it's a huge improvement if we introduce the Frustrated Lewis Pairs (FLPs) such as Carbon-Phosphorous bonds into the hydrogen-storage compounds. Presently, we design 7 compounds containing FLPs structures and 14 pathways of (de)hydrogenation based on the experiments and compare their properties of hydrogenation kinetically and thermodynamically.",_
!302,"The implementation of a future economy based on hydrogen-related energy needs an urgent development of efficient, safe, and economic solid-state hydrogen-storage materials. During the search process for novel materials for storing hydrogen, research interests in the past few decades have been intensively focused on light metal borohydrides and amides as two representative chemical complex hydrides with high hydrogen capacities. Recently, a large number of studies have reported new borohydride/amide combined systems that expand the scope of hydrogen-storage materials. Here, we review the interaction between light metal borohydrides and amides for storing hydrogen, with a special emphasis on the synthetic strategies and structural, physical, and chemical properties, which reveal a correlation between the composition, structure, and dehydrogenation properties and also provide general principles to the design of new combined systems with tailored functionality. This review also demonstrates the current progress on the dehydrogenation kinetic improvement of borohydride/amide combined systems. © 2017 The Royal Society of Chemistry.","The implementation of a future economy based on hydrogen-related energy needs an urgent development of efficient, safe, and economic solid-state hydrogen-storage materials. During the search process for novel materials for storing hydrogen, research interests in the past few decades have been intensively focused on light metal borohydrides and amides as two representative chemical complex hydrides with high hydrogen capacities.",_
!303,"Hydride nanocomposites in the (LiNH2 + nMgH2) system have been synthesized by ball milling with varying input of milling energy injected into powder particles, QTR (kJ/g). The grain (crystallite) size of LiNH2 and MgH2 decreases rapidly with increasing QTR up to approximately 150-200 kJ/g and subsequently more or less saturates at the value of 10-20 nm. For the injected energy QTR ≈ 250-350 kJ/g the specific surface area (SSA) increases from the initial 2.4 m2/g for powder mixtures before milling to 30-37 m2/g for nanocomposites after milling. After injecting QTR ≈ 550 kJ/g there is a further increase of SSA to 52 m2/g which is over 20-fold increase of SSA from its initial value. That clearly indicates that a profound reduction of particle size has occurred. The hydride phases formed during ball milling with relatively low QTR are identified as a-Mg(NH 2)2 (amorphous magnesium imide) and LiH. The ball milled (LiNH2 + nMgH2) nanocomposite system with n = 0.5-0.9 can effectively desorb about 4-5 wt.% H2 with a reasonable rate at the temperature range close to 200 °C. Within a low temperature range up to ∼250 °C, regardless of the molar ratio n and the injected energy Q TR the thermal desorption of the (LiNH2 + nMgH 2) nanocomposites occurs without any release of ammonia, NH 3. For all molar ratios, n, the hydride nanocomposites are fully reversible at 175 °C under a relatively mild pressure of 50 bar H 2. The quantity of H2 desorbed decreases with increasing molar ratio n, due to increasing fraction of inactive, retained MgH2. However, at 125 °C the dehydrogenation rate is very sluggish and the quantity of released H2 is minimal. At the temperature range lower than ∼250 °C dehydrogenation of ball milled nanocomposites occurs through formation of the Li2Mg(NH)2 hydride phase. The value of the measured dehydrogenation enthalpy change of 46.7 kJ/molH 2 is relatively low and apparently, it is not responsible for sluggish dehydrogenation at 125 °C. The measurements of thermal conductivity for non-milled powders and ball milled nanocomposites show a dramatic reduction of thermal conductivity after ball milling. It seems that this could be a principal factor responsible for such a low dehydrogenation rate at low temperatures. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","The hydride phases formed during ball milling with relatively low QTR are identified as a-Mg(NH 2)2 (amorphous magnesium imide) and LiH. For all molar ratios, n, the hydride nanocomposites are fully reversible at 175 °C under a relatively mild pressure of 50 bar H 2.",_
!304,"Owing to a theoretical hydrogen storage capacity of 10.5 wt% H2, Ca(BH4)2+MgH2, the so-called calcium reactive hydride composite (Ca-RHC), has a great potential as a hydrogen storage material. However, its dehydrogenation temperature (∼623 K) is too high for any mobile applications. By addition of 10 mol% of NbF5 into Ca(BH4)2+MgH2, a decrease of the dehydrogenation onset temperature by ∼120 K is observed. In order to understand the reasons behind this desorption temperature decrement two sets of samples [Ca(BH4)2+MgH2 and Ca(BH4)2+MgH2+0.1NbF5] in different hydrogenation states, were prepared. The structural investigation of the above mentioned sets of samples by means of volumetric measurements, anomalous small-angle X-ray scattering (ASAXS) and X-ray absorption spectroscopy (XAS) is reported here. The XAS results show that after the milling procedure NbB2 is formed and remains stable upon further de/rehydrogenation cycling. The results of Nb ASAXS point to nanometric spherical NbB2 particles distributed in the hydride matrix, with a mean diameter of ∼10 nm. Results from Ca ASAXS indicate Ca-containing nanostructures in the Ca-RHC+0.1NbF5 samples to be ∼50% finer compared to those without additive. Thus, a higher reaction surface area and shorter diffusion paths for the constituents are concluded to be important contributions to the catalytic effect of an NbF5 additive on the hydrogen sorption kinetics of the Ca(BH4)2+MgH2 composite system. © 2014 International Union of Crystallography.","However, its dehydrogenation temperature (∼623 K) is too high for any mobile applications. In order to understand the reasons behind this desorption temperature decrement two sets of samples [Ca(BH4)2+MgH2 and Ca(BH4)2+MgH2+0.1NbF5] in different hydrogenation states, were prepared.",_
!305,"Magnesium hydride is one of the most promising candidates for solid-state hydrogen storage and thermal energy storage applications. The effects of V-based solid solution alloys on the hydrogenation and dehydrogenation behavior of magnesium hydride are studied. Significant reduction of the dehydrogenation temperature and improvements of the kinetics of both absorption and desorption reactions were observed for MgH2with V-based additives. Those observations were made using thermogravimetric analysis (TGA) and pressure-composition-temperature (PCT) techniques. In situ synchrotron X-ray diffraction (XRD) measurements suggest that the additives functioned as catalysts during the reactions. The comparison of the characteristics of different additives suggested that the hydrogen equilibrium pressures of those additives themselves have a significant bearing on their effects on the kinetic behaviors of MgH2. The lower is the stability of an additive as a hydride, the more effective it would be as a catalyst. © 2014 American Chemical Society.",The effects of V-based solid solution alloys on the hydrogenation and dehydrogenation behavior of magnesium hydride are studied. Those observations were made using thermogravimetric analysis (TGA) and pressure-composition-temperature (PCT) techniques.,_
!306,"The alkali metal silanides α-MSiH3 appear to be a promising family of complex hydrides for solid-state hydrogen storage. Herein the structural, energetic and electronic properties of α-MSiH3 silanides (M = Li, Na, K, Rb, Cs) and MSi Zintl phases are systematically investigated for the first time by using first-principles calculations method based on density functional theory. The structural parameters of α-MSiH3 and MSi including lattice constants and atomic positions are determined through geometry optimization. The obtained results are close to the experimental data analysed from X-ray and neutron powder diffraction. The calculations of formation enthalpy show that α-KSiH3, α-RbSiH3 and α-CsSiH3 silanides are easier to be synthetized relative to α-LiSiH3 and α-NaSiH3, which interprets well the lower thermostabilities of experimental α-LiSiH3 and α-NaSiH3. Nevertheless, LiSi, KSi and CsSi phases are easier to be formed relative to NaSi and RbSi. The calculations of hydrogen desorption enthalpy reveal that the dehydrogenation abilities of α-MSiH3 silanides along the decomposition path of α-MSiH3→MSi + H2 are gradually enhanced in the order of α-CsSiH3, α-RbSiH3, α-KSiH3, α-NaSiH3 and α-LiSiH3, which may be originated from their decreasing thermostabilities. From a comprehensive point of view including hydrogen storage capacity, thermostability and dehydrogenation ability, α-KSiH3 (∼4.29 wt%) is identified as the most promising alkali metal silanide for reversible hydrogen storage. Analysis of electronic structures indicates that a significant charge transfer leads to positively charged M ions and negatively charged SiH3 complex, which constitutes the ionic bonding between them. The bonding within SiH3 complex not only involves the covalent hybridization between Si (3s) (3p) and H (1s) orbitals, but also exhibits some ionic bond characteristics due to the partial charge transfer from Si to H. The covalent bonding interactions between H and Si atoms within SiH3 mainly dominate the thermostabilities and dehydrogenation properties of α-MSiH3 silanides. © 2017 Hydrogen Energy Publications LLC","The alkali metal silanides α-MSiH3 appear to be a promising family of complex hydrides for solid-state hydrogen storage. Herein the structural, energetic and electronic properties of α-MSiH3 silanides (M = Li, Na, K, Rb, Cs) and MSi Zintl phases are systematically investigated for the first time by using first-principles calculations method based on density functional theory.",_
!307,"LiBH4 is considered as a prominent solid state hydrogen storage material with 18.3 wt% hydrogen storage capacity, while suffering sluggish dehydrogenation kinetics and poor reversibility. It is hypothesized that nano scale LiBH4 and catalyst mixture will show improved dehydrogenation performance. In this study, LiBH4 and Ni catalyst precursors were well mixed in organic solvent with activated carbon, followed by freeze drying and thermal reduction process. The as-prepared sample showed a nano Ni decorated LiBH4 clusters covered by the thin film of activated carbon, which helped reduce the doping amount of Ni catalyst and improve the reversibility of LiBH4. The onset of LiBH4 decomposition temperature was reduced to 243 °C with the first main hydrogen releasing peak at 278 °C. The sample desorbs 5.5 wt% hydrogen within 1 h at 330 °C. Although underwent serious degradation, a partial reversibility was observed under 9 MPa hydrogen pressure for 3 h at 400 °C. © 2014 Elsevier B.V. All rights reserved.","It is hypothesized that nano scale LiBH4 and catalyst mixture will show improved dehydrogenation performance. Although underwent serious degradation, a partial reversibility was observed under 9 MPa hydrogen pressure for 3 h at 400 °C.",_
!308,"In this review, we discuss the evolution of localized surface plasmon resonance and surface plasmon resonance hydrogen sensors based on nanostructured metal hydrides, which has accelerated significantly during the past 5 years. We put particular focus on how, conceptually, plasmonic resonances can be used to study metal-hydrogen interactions at the nanoscale, both at the ensemble and at the single-nanoparticle level. Such efforts are motivated by a fundamental interest in understanding the role of nanosizing on metal hydride formation processes in the quest to develop efficient solid-state hydrogen storage materials with fast response times, reasonable thermodynamics, and acceptable long-term stability. Therefore, a brief introduction to the thermodynamics of metal hydride formation is also given. However, plasmonic hydrogen sensors not only are of academic interest as research tool in materials science but also are predicted to find more practical use as all-optical gas detectors in industrial and medical applications, as well as in a future hydrogen economy, where hydrogen is used as a carbon free energy carrier. Therefore, the wide range of different plasmonic hydrogen sensor designs already available is reviewed together with theoretical efforts to understand their fundamentals and optimize their performance in terms of sensitivity. In this context, we also highlight important challenges to be addressed in the future to take plasmonic hydrogen sensors from the laboratory to real applications in devices, including poisoning/deactivation of the active materials, sensor lifetime, and cross-sensitivity toward other gas species. © 2014 American Chemical Society.","Such efforts are motivated by a fundamental interest in understanding the role of nanosizing on metal hydride formation processes in the quest to develop efficient solid-state hydrogen storage materials with fast response times, reasonable thermodynamics, and acceptable long-term stability. Therefore, a brief introduction to the thermodynamics of metal hydride formation is also given.",_
!309,"The phase transformations occurring as a function of the ball milling energy injected into the hydride system (LiNH2 + nMgH2), having molar ratios n = 0.5-2.0, have been thoroughly studied. The milling energy in a magneto-mill is estimated by a semi-empirical method. X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) measurements show that for the molar ratios n < 1.0 three new phases such as LiH, amorphous Mg(NH2)2 (a-Mg(NH2)2) and Li 2Mg(NH)2 are formed during ball milling depending on the injected quantity of milling energy. Hydrogen is not released during milling when the LiH and a-Mg(NH2)2 hydrides are being formed whereas the formation of the Li2Mg(NH)2 hydride phase is always accompanied by a profound release of hydrogen. For the molar ratios n ≥ 1.0, at a low level of injected milling energy, the hydride phases formed are LiH and a-Mg(NH2)2. The latter reacts with MgH 2 during further milling to form the new phase MgNH whose formation is also accompanied by a profound release of hydrogen. Based on the experimental data we established an approximate hydride phase-injected milling energy diagram for various levels of injected milling energy and the molar ratios. © Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) measurements show that for the molar ratios n < 1.0 three new phases such as LiH, amorphous Mg(NH2)2 (a-Mg(NH2)2) and Li 2Mg(NH)2 are formed during ball milling depending on the injected quantity of milling energy. Based on the experimental data we established an approximate hydride phase-injected milling energy diagram for various levels of injected milling energy and the molar ratios.",_
!310,"In Part A of this manuscript which consists of two parts, the experimental investigations pertaining to the absorption of hydrogen in an LmNi 4.91Sn0.15 based solid state hydrogen storage device with embedded cooling tubes (ECT) are presented. Two metal hydride based hydrogen storage devices with 36 and 60 ECT filled with 2.75 kg of LmNi 4.91Sn0.15 were fabricated. Performances of the hydrogen storage devices in terms of hydrogen absorption rate and amount of hydrogen absorbed are reported for different supply pressures (10-35 bar), absorption temperatures (20-30 C) and cooling fluid flow rates (2.2-30 l/min). At any given absorption temperature, the rate of hydrogen absorption and the amount of hydrogen absorbed are found to increase with hydrogen supply pressure up to about 35 bar. At the supply condition of 35 bar hydrogen pressure and 30 C absorption temperature, with oil as a heat transfer fluid at a flow rate of 3.2 l/min, the maximum amount of hydrogen absorbed are ≈1.18 wt% in 10 min for 36 ECT, and 8 min for 60 ECT. At the absorption condition of 25 bar supply pressure, 30 l/min water flow rate and 30 C absorption temperature, the absorption time of the reactor with 60 ECT was reduced to 5 min. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserver.","In Part A of this manuscript which consists of two parts, the experimental investigations pertaining to the absorption of hydrogen in an LmNi 4.91Sn0.15 based solid state hydrogen storage device with embedded cooling tubes (ECT) are presented. At the supply condition of 35 bar hydrogen pressure and 30 C absorption temperature, with oil as a heat transfer fluid at a flow rate of 3.2 l/min, the maximum amount of hydrogen absorbed are ≈1.18 wt% in 10 min for 36 ECT, and 8 min for 60 ECT.",_
!311,"Feasibility of using hydrochloric acid (HCl) as an accelerator for onboard production of hydrogen from sodium borohydride (NaBH4) is investigated. The aim was to examine process efficiency, hydrogen purity and process controllability which concurs onboard 2015 hydrogen storage target (5.5 wt%) for vehicular fuel cell system application. Results showed that a highest yield and controllable hydrogen production rate are achievable upon adopting onboard reaction of HCl (3 M) and an aqueous alkaline solution of 30 % NaBH4 via a T-junction and applying a gas–liquid separation of two stages. Cost evaluation and product stream analysis have demonstrated an exceptional performance for the examined scheme and relevancy to be adopted for feeding vehicular electrochemical fuel cell systems. © 2014, The Author(s).","The aim was to examine process efficiency, hydrogen purity and process controllability which concurs onboard 2015 hydrogen storage target (5.5 wt%) for vehicular fuel cell system application. Cost evaluation and product stream analysis have demonstrated an exceptional performance for the examined scheme and relevancy to be adopted for feeding vehicular electrochemical fuel cell systems.",_
!312,"The use of transmission electron microscopy (TEM) for the structural characterization of many nanostructured hydrides, which are relevant for solid state hydrogen storage, is hindered due to a rapid decomposition of the specimen upon irradiation with the electron beam. Environmental TEM allows to stabilize the hydrides by applying a hydrogen back pressure of up to 4.5 bar in a windowed environmental cell. The feasibility of high-resolution TEM (HRTEM) investigations of light weight metals and metal hydrides in such a “nanoreactor” is studied theoretically by means of multislice HRTEM contrast simulations using Mg and its hydride phase, MgH2, as model system. Such a setup provides the general opportunity to study dehydrogenation and hydrogenation reactions at the nanoscale under technological application conditions. We analyze the dependence of both the spatial resolution and the HRTEM image contrast on parameters such as the defocus, the metal/hydride thickness, and the hydrogen pressure in order to explore the possibilities and limitations of in-situ experiments with windowed environmental cells. Such simulations may be highly valuable to pre-evaluate future experimental studies. © 2017 Elsevier B.V.",Environmental TEM allows to stabilize the hydrides by applying a hydrogen back pressure of up to 4.5 bar in a windowed environmental cell. Such simulations may be highly valuable to pre-evaluate future experimental studies.,_
!313,"Since the current transportation sector is the largest consumer of oil, and subsequently responsible for major air pollutants, it is inevitable to use alternative renewable sources of energies for vehicular applications. The hydrogen energy seems to be a promising candidate. To explore the possibility of achieving a solid-state high-capacity storage of hydrogen for onboard applications, we have performed first-principles density functional theoretical calculations of hydrogen storage properties of beryllium oxide clusters (BeO)n (n = 2-8). We observed that a polar BeO bond is responsible for H2 adsorption. The problem of cohesion of beryllium atoms does not arise, as they are an integral part of BeO clusters. The (BeO)n (n = 2-8) adsorbs 8-12 H2 molecules with an adsorption energy in the desirable range of reversible hydrogen storage. The gravimetric density of H2 adsorbed on BeO clusters meets the ultimate 7.5 wt % limit, recommended for onboard practical applications. In conclusion, beryllium oxide clusters exhibit a remarkable solid-state hydrogen storage. © 2014 American Chemical Society.","Since the current transportation sector is the largest consumer of oil, and subsequently responsible for major air pollutants, it is inevitable to use alternative renewable sources of energies for vehicular applications. We observed that a polar BeO bond is responsible for H2 adsorption.",_
!314,"Magnesium hydride is a very promising material for solid-state hydrogen storage. However, some drawbacks have to be overcome to use it in real applications. The use of catalysts is a viable solution to lower the desorption temperature and increase the overall kinetics. An accurate model has been developed to study the mechanism of action of the catalyst and how it interacts with the interface MgH2-Mg, through which H atoms diffuse. The accurate evaluation of the work of adhesion and defect energy formation, versus the distance from the interface are linked to the atomic-scale structural distortion induced by the catalyst. Moreover, molecular dynamics simulations at several temperature provide a clear description of the desorption mechanism and an estimate of the desorption temperature. © 2015 Hydrogen Energy Publications, LLC.","Magnesium hydride is a very promising material for solid-state hydrogen storage. Moreover, molecular dynamics simulations at several temperature provide a clear description of the desorption mechanism and an estimate of the desorption temperature.",_
!315,"Solid-state hydrogen storage through the reversible formation of metallic hydrides is a key issue for the development of hydrogen as an energy vector. Herein we report the hydrogen storage performances of the KSiH3 phase ball-milled with NbF5 as a catalyst. The kinetics of hydrogen absorption/desorption are strongly enhanced by the addition of a catalyst as revealed by the large decrease of activation energies for both the absorption and desorption reactions. No disproportionation phenomenon is observed, indicating that the reaction between KSiH3 and KSi is perfectly reversible with a hydrogen storage capacity of 4.1 wt% H2. The thermodynamic properties of this KSi/KSiH3 equilibrium were investigated by plotting PCI curves from 90 °C to 130 °C: an enthalpy of 24.3 kJ mol-1 H2 and a low entropy change of 59.5 J K-1 mol-1 H2 are found. This low entropy variation is related to the high mobility of the H atoms in the α-KSiH3 phase as recently demonstrated by Quasi-Elastic Neutron Scattering (QENS) experiments. © The Royal Society of Chemistry.","Solid-state hydrogen storage through the reversible formation of metallic hydrides is a key issue for the development of hydrogen as an energy vector. No disproportionation phenomenon is observed, indicating that the reaction between KSiH3 and KSi is perfectly reversible with a hydrogen storage capacity of 4.1 wt% H2.",_
!316,"Isosteric heat of hydrogen adsorption is one of the most important parameters required to describe solid-state hydrogen storage systems. Typically, it is calculated from adsorption isotherms measured at 77K (liquid N2) and 87K (liquid Ar). This simple calculation, however, results in a high degree of uncertainty due to the small temperature range. Therefore, the original Sievert type setup is upgraded using a heating and cooling device to regulate the wide sample temperature. This upgraded setup allows a wide temperature range for isotherms (77K~ 117K) providing a minimized uncertainty (error) of measurement for adsorption enthalpy calculation and yielding reliable results. To this end, we measure the isosteric heats of hydrogen adsorption of two prototypical samples: Activated carbon and metal-organic frameworks (e.g. MIL-53), and compared the small temperature range (77~87K) to the wide one (77K~ 117K). © Materials Research Society of Korea.","This simple calculation, however, results in a high degree of uncertainty due to the small temperature range. This upgraded setup allows a wide temperature range for isotherms (77K~ 117K) providing a minimized uncertainty (error) of measurement for adsorption enthalpy calculation and yielding reliable results.",_
!317,"Complex hydrides have energy storage-related functions such as i) solid-state hydrogen storage, ii) electrochemical Li storage, and iii) fast Li- and Na-ionic conductions. Here, recent progress on the development of fast Li-ionic conductors based on the complex hydrides is reported. The validity of using them as electrolytes in all-solid-state lithium rechargeable batteries is also examined. Not only coated oxides but also bare sulfides are found to be applicable as positive electrode active materials. Results related to fast Na-ionic conductivity in the complex hydrides are presented. In the last section, the future prospects for battery assemblies with high-energy densities, and Mg ion batteries with the liquid and the solid-state electrolytes are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.",The validity of using them as electrolytes in all-solid-state lithium rechargeable batteries is also examined. Not only coated oxides but also bare sulfides are found to be applicable as positive electrode active materials.,_
!318,"MgH2 is a promising material for reversible solid-state hydrogen storage. It is known that particle size can have a strong impact on hydrogen dynamics and sorption characteristics, but more detailed insight has been hampered by the great challenge to prepare small and well-defined particles and study their hydrogen storage properties upon cycling. The preparation of MgH2 nanoparticles supported on high surface area carbon aerogels with pore sizes varying from 6-20 nm is reported. Two distinctly different MgH2 particle populations are observed: X-ray diffraction invisible nanoparticles with sizes below 20 nm, and larger, crystalline, MgH2 particles. They release hydrogen at temperatures 140 °C lower than bulk MgH2. The size-dependent hydrogen kinetics is for the first time corroborated by intrinsic hydrogen dynamics data obtained by solid state 1H NMR. Fast cycling is possible (80% of the capacity absorbed within 15 min at 18 bar and 300 °C), without a change in the hydrogen sorption properties, showing that the growth of the nanoparticles is effectively prevented by the carbon support. A clear correlation is found between the hydrogen desorption temperature and the size of the MgH2 nanoparticles. This illustrates the potential of the use of supported nanoparticles for fast, reversible, and stable hydrogen cycling. Supported MgH2 nanoparticles on carbon with different sizes are synthesized and show faster hydrogen mobility and sorption kinetics. Nanoparticles with sizes below 20 nm have a significant lower hydrogen release temperature and the mobility is three orders of magnitude faster compared to micrometer sized MgH2. The smaller the MgH2 particles, the lower the hydrogen release temperatures become. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.",The preparation of MgH2 nanoparticles supported on high surface area carbon aerogels with pore sizes varying from 6-20 nm is reported. Nanoparticles with sizes below 20 nm have a significant lower hydrogen release temperature and the mobility is three orders of magnitude faster compared to micrometer sized MgH2.,_
!319,"We present ab initio calculations to find the migration pathways of the hydrogen atom through Stone-Wales defects into the inside of the double-shell fullerene. We report that the most favorable pathway consists of the tunneling pathway through Stone-Wales defects on the double-shell C60/C 240 fullerene. This tunneling pathway gives rise to three barrier heights of 0.54eV, 0.47eV, and 0.7eV. The driving force for the hydrogen atom diffusion through the tunneling pathway towards the inside of the double-shell fullerene is 0.82eV. Our findings lead to a relatively low energy pathway, which provides a practical route to develop newly inexpensive solid-state hydrogen storages. © 2013 AIP Publishing LLC.","This tunneling pathway gives rise to three barrier heights of 0.54eV, 0.47eV, and 0.7eV. Our findings lead to a relatively low energy pathway, which provides a practical route to develop newly inexpensive solid-state hydrogen storages.",_
!320,"Practical hydrogen storage for vehicular applications requires materials with high hydrogen densities, low decomposition temperature and fast adsorption and desorption kinetics. Till date, no reversible materials are currently known that posses all these attributes. Experimentally, testing the hydrogen storage capacity of a new material not only requires synthesis of a material but also the high precision equipments. The proposed material should also satisfy the target set by the US Department of Energy (DOE). If not, another material has to be synthesized. Theoretical H2 storage properties of a material can be evaluated precisely, and this may provide the mechanism to experimentalists for synthesizing such materials. Recent high performance computational techniques help us to predict the theoretical hydrogen uptake capacity of a material and provide information about its structure, stability and kinetics. Owing to their high uptake capacity at low temperature, structure stability, and excellent reversibility kinetics, organometallic nanostructures have attracted considerable attention as potential solid- state hydrogen storage materials. Here, the results from quantum chemical calculations on adsorption of dihydrogens on various organometallic complexes have been presented. Potential materials that were suited for storage of hydrogen in molecular form are particularly considered. The gravimetric H2 capacity of Scandium-decorated ethylene complex (14 wt%) is found to be well above the target specified by US DOE (5.5 wt% by 2015). Its cation adsorbs one additional molecule than the neutral thereby showing higher gravimetric H2 uptake by about 2 wt% than the neutral. Calculated averaged gain in energy of the complex favored for fast hydrogen adsorption and desorption kinetics. As found from many-body analysis technique, the H2 molecules interact strongly with the cation of C2H4:Sc than the neutral indicating an increase in metal bond strength. In case of Ti:C2H4 organometallic compound, it is found that the ionization process greatly improves its uptake capacity. The predicted gravimetric hydrogen uptake capacity of Ti:C2H4 (11.7 wt%) is in excellent agreement with the experimental value (12 wt%) reported earlier. Average Gibbs free energy correction was found to be as large as 0.45 eV and 0.44 eV for neutral and cation complexes, respectively. The Density Functional Theory (DFT) functionals as well as basis sets affect the averaged H2 adsorption energy with Gibbs free energy correction. The theoretical calculation of Equilibrium Isotope Effect (EIE) was also described. The vibrational frequencies of Ti:C2H4(nH2) and Ti:C2H4(nD2) for different 'n' are used to evaluate the EIE. The calculated EIE of 0.66 (for n=5) is also in excellent agreement with the experimental findings. Similar results were found in case of V:C2H4 complex. Hydrogen uptake capacity of V-capped and V-inserted V:C3H3 complexes was predicted and compared with other organometallic complexes containing single V atom decorated on different CnHn (n > 3) ring templates. The H2 uptake capacity of V:C3H3 organometallic compound is higher than other V-decorated CnHn (n > 3) ring templates reported earlier. The H2 adsorption on the V:C3H3 complex was found to be energetically favorable at finite temperature. The predicted hydrogen uptake capacity of the above systems was confirmed by the ab initio molecular dynamics simulations. © 2015 by Nova Science Publishers, Inc. All rights reserved.","Theoretical H2 storage properties of a material can be evaluated precisely, and this may provide the mechanism to experimentalists for synthesizing such materials. Owing to their high uptake capacity at low temperature, structure stability, and excellent reversibility kinetics, organometallic nanostructures have attracted considerable attention as potential solid- state hydrogen storage materials.",_
!321,"2 LiNH2-1.1 MgH2-0.1 LiBH4-3 wt.% ZrCoH3 is a solid state hydrogen storage material with a hydrogen storage capacity of up to 5.3 wt.%. As the material shows sufficiently high desorption rates at temperatures below 200 °C, it is used for a prototype solid state hydrogen storage tank with a hydrogen capacity of 2 kWhel that is coupled to a high temperature proton exchange membrane fuel cell. In order to design an appropriate prototype reactor, model equations for the rate of hydrogen sorption reactions are required. Therefore in the present study, several material properties, like bulk density and thermodynamic data, are measured. Furthermore, isothermal absorption and desorption experiments are performed in a temperature and pressure range that is in the focus of the coupling system. Using experimental data, two-step model equations have been fitted for the hydrogen absorption and desorption reactions. These empirical model equations are able to capture the experimentally measured reaction rates and can be used for model validation of the design simulations. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","In order to design an appropriate prototype reactor, model equations for the rate of hydrogen sorption reactions are required. Therefore in the present study, several material properties, like bulk density and thermodynamic data, are measured.",_
!322,"Nanostructured materials based on light elements such as Li, Mg, and Na are essential for energy storage and conversion applications, but often difficult to prepare with control over size and structure. We report a new strategy that is illustrated for the formation of magnesium boron hydrides, relevant compounds for instance for reversible solid state hydrogen storage. We started with small (5-10 nm) MgH2 nanoparticles inside the ∼10 nm pores of a carbon scaffold, and larger MgH2 crystallites on the exterior surface of the scaffold. The large difference in reactivity between the two types of MgH2 is used to selective react the small MgH2 particles inside the pores with B2H6 to form magnesium boron hydrides under mild conditions. In this way pore-confined magnesium boron hydrides are formed with MgB12H12 as the major phase. Hydrogen release from the confined magnesium boron hydrides starts just above the synthesis temperature of 120 °C. The addition of Ni brings about the reaction to proceed readily at temperatures as low as 30 °C. Furthermore, by Ni addition and tuning the synthesis temperature, the product distribution can be steered toward Mg(BH4)2 and other magnesium boron hydrides. This shows the suitability of our method to selectively form pore-confined complex metal hydrides, such as MgB12H12 for which no synthesis strategy had been reported until now. This strategy might also be relevant for other novel energy storage and conversion materials, which are difficult to nanostructure in a controlled manner by conventional methods. © 2014 American Chemical Society.","This shows the suitability of our method to selectively form pore-confined complex metal hydrides, such as MgB12H12 for which no synthesis strategy had been reported until now. This strategy might also be relevant for other novel energy storage and conversion materials, which are difficult to nanostructure in a controlled manner by conventional methods.",_
!323,"Hydrogen has been widely recognized as the ""Energy Carrier"" of the future. Efficient, reliable, economical and safe storage and delivery of hydrogen form important aspects in achieving success of the ""Hydrogen Economy"". Gravimetric and volumetric storage capacities become important when one considers portable and mobile applications of hydrogen. In the case of solid state hydrogen storage, the gas is reversibly embedded (by physisorption and/or chemisorption) in a solid matrix. A wide variety of materials such as intermetallics, physisorbents, complex hydrides/alanates, metal organic frameworks, etc. have been investigated as possible storage media. This paper discusses the feasibility of lithium- and sodium-aluminum hydrides with emphasis on their thermodynamic and thermo-physical properties. Drawbacks such as poor heat transfer characteristics and poor kinetics demand special attention to the thermal design of solid state storage devices. © 2014 Elsevier Ltd. All rights reserved.","A wide variety of materials such as intermetallics, physisorbents, complex hydrides/alanates, metal organic frameworks, etc. Drawbacks such as poor heat transfer characteristics and poor kinetics demand special attention to the thermal design of solid state storage devices.",_
!324,"The combination of unstable hydrogen storage materials with a high pressure tank provides a potential solution to on-board hydrogen storage system for fuel cell vehicles. However, none of the available solid-state materials can fulfill all the requirements. In this work, Zr-Fe-V-based alloys were systematically investigated for the possible use in such kind of hybrid storage devices. Among these alloys studied here, the composition (Zr0.7Ti0.3)1.04Fe1.8V0.2 shows the best overall properties with a reversible hydrogen capacity of 1.51 wt%, and a hydrogen desorption pressure of 11.2 atm at 0 °C. Besides, this alloy also shows excellent stability without obvious capacity loss even after 200 hydrogen absorption/desorption cycles. Calculated results show that the gravimetric density of the hybrid storage system combining a 35 MPa high pressure tank with (Zr0.7Ti0.3)1.04Fe1.8V0.2 alloy is 1.95 wt% when the volumetric density reaches 40 kg/m3. © 2016 Hydrogen Energy Publications LLC.","Among these alloys studied here, the composition (Zr0.7Ti0.3)1.04Fe1.8V0.2 shows the best overall properties with a reversible hydrogen capacity of 1.51 wt%, and a hydrogen desorption pressure of 11.2 atm at 0 °C. Besides, this alloy also shows excellent stability without obvious capacity loss even after 200 hydrogen absorption/desorption cycles.",_
!325,"Magnesium acetate was micronized by the supercritical antisolvent (SAS) process. By SAS processing, submicrometric magnesium acetate particles with particle sizes ranging from 300 to 700 nm with a regular spherical morphology and an amorphous crystalline structure were obtained. In comparison, mechanically milled particles showed similar mean particle sizes but had an irregular morphology and a bimodal particle size distribution. By calcination, SAS-processed magnesium acetate was converted into magnesium oxide, preserving the morphology of particles. By hydrogenation, the acetate was converted into magnesium hydride, a solid-state hydrogen storage metal hydride. The rate of release of hydrogen by thermolysis of magnesium hydride was enhanced by the particle size reduction, and there was a direct relationship between the size achieved by SAS micronization of the magnesium acetate precursor and the rate of release of hydrogen from the hydride. © 2014 American Chemical Society.","Magnesium acetate was micronized by the supercritical antisolvent (SAS) process. By SAS processing, submicrometric magnesium acetate particles with particle sizes ranging from 300 to 700 nm with a regular spherical morphology and an amorphous crystalline structure were obtained.",_
!326,"Complex hydrides are a family of compounds which have attracted a lot of attention in the last decade for various clean energy-related purposes, from solid state hydrogen storage to materials suitable in Li-ion batteries. We present two new garnet-type borohydride materials suitable as solid state electrolytes. Li3K3Ce2(BH4)12 and Li3K3La2(BH4)12 show unexpectedly high room temperature Li+ ionic conductivity (compared to the reported isostructural garnet oxide Li-conductor) of σLi 3 × 10-7 and 6 × 10-7 S/cm with corresponding activation energies of Ea = 0.79 and Ea = 0.67 eV, respectively, which result from large bottleneck windows in the conduction path. The effect of heterovalent cation substitution is investigated as means of tailoring ionic conductivity. Doping with divalent Sr2+ and Eu2+ shows that σLi can be increased by one order of magnitude in the whole temperature range measured. © 2015 Elsevier B.V. All rights reserved.","Complex hydrides are a family of compounds which have attracted a lot of attention in the last decade for various clean energy-related purposes, from solid state hydrogen storage to materials suitable in Li-ion batteries. Doping with divalent Sr2+ and Eu2+ shows that σLi can be increased by one order of magnitude in the whole temperature range measured.",_
!327,"One of the current main challenges in green-power storage and smart grids is the lack of effective solutions for accommodating the unbalance between renewable energy sources-offering intermittent electricity supply-and a variable electricity demand. Integrating intermittent renewable energy sources by safe and cost-effective energy storage systems is today achievable. Coupled with electrolizers, high-capacity solid-state storage of green-hydrogen is practicable to sustain integration, monitoring and control of large quantity of GWh from renewable generation. The 23.9 MLN Euros INGRID European large demonstrative project started in July 2012 combines magnesium-based material solid-state hydrogen storage systems with advanced ICT technologies to intelligently interconnect miscellaneous energy networks (i.e. electricity and gas) and safely delivering green-hydrogen to various existing or forthcoming markets. One solution INGRID project addresses is an off-grid utility to store renewable electricity captured from wind sources to refill full-battery electric cars. © 2016 by The Minerals. Metals & Materials Society.",The 23.9 MLN Euros INGRID European large demonstrative project started in July 2012 combines magnesium-based material solid-state hydrogen storage systems with advanced ICT technologies to intelligently interconnect miscellaneous energy networks (i.e. electricity and gas) and safely delivering green-hydrogen to various existing or forthcoming markets. One solution INGRID project addresses is an off-grid utility to store renewable electricity captured from wind sources to refill full-battery electric cars.,_
!328,"Herein, we present the effect of the nanoconfinement of LiBH4 within porous aerogel-like carbon on its hydrogen storage properties. The carbon scaffold is prepared by salt templating - a facile and sustainable technique for the production of micro- and mesoporous carbon-based materials. A loading of up to 40 wt. % of LiBH4 is achieved by melt infiltration, and the hydride remains amorphous as shown by differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and scanning transmission electron microscopy (STEM). Simultaneous thermogravimetry and mass spectroscopy (TG-MS) reveal that the nanoconfined LiBH4 starts to desorb hydrogen already at 200 °C with the main release at 310 °C. A partial rehydrogenation at moderate conditions (100 bar and 300 °C) is demonstrated. In contrast to recent reports, in-situ heating in the transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) indicate that both decomposition products (B and LiH) remain within the carbon pores. Nuclear magnetic resonance (NMR) measurements reveal the presence of amorphous and partially oxidized boron in the dehydrogenated sample that may impede the reversibility of the (de)hydrogenation process. © 2016 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","% of LiBH4 is achieved by melt infiltration, and the hydride remains amorphous as shown by differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and scanning transmission electron microscopy (STEM). In contrast to recent reports, in-situ heating in the transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) indicate that both decomposition products (B and LiH) remain within the carbon pores.",_
!329,"The main objective of the SSH2S (Fuel Cell Coupled Solid State Hydrogen Storage Tank) project was to develop a solid state hydrogen storage tank based on complex hydrides and to fully integrate it with a High Temperature Proton Exchange Membrane (HT-PEM) fuel cell stack. A mixed lithium amide/magnesium hydride system was used as the main storage material for the tank, due to its high gravimetric storage capacity and relatively low hydrogen desorption temperature. The mixed lithium amide/magnesium hydride system was coupled with a standard intermetallic compound to take advantage of its capability to release hydrogen at ambient temperature and to ensure a fast start-up of the system. The hydrogen storage tank was designed to feed a 1 kW HT-PEM stack for 2 h to be used for an Auxiliary Power Unit (APU). A full thermal integration was possible thanks to the high operation temperature of the fuel cell and to the relative low temperature (170 °C) for hydrogen release from the mixed lithium amide/magnesium hydride system. © 2017 Elsevier B.V.","The main objective of the SSH2S (Fuel Cell Coupled Solid State Hydrogen Storage Tank) project was to develop a solid state hydrogen storage tank based on complex hydrides and to fully integrate it with a High Temperature Proton Exchange Membrane (HT-PEM) fuel cell stack. A mixed lithium amide/magnesium hydride system was used as the main storage material for the tank, due to its high gravimetric storage capacity and relatively low hydrogen desorption temperature.",_
!330,"Nanocrystalline MgH2 powders were prepared by reactive ball milling of pure Mg powders under 50 bar of a hydrogen gas atmosphere, using a high energy ball mill operated at room temperature. The end-product of MgH2 powders obtained after 200 h of a continuous ball milling time composed of γ and β phases. The end-product was doped with 7 wt% of Mn3.6Ti2.4 powders and then mechanically milled under a hydrogen gas atmosphere for 50 h, using a high energy ball mill for different ball milling time. This end product coexisted with Fe and Cr contamination contents of 2.16 and 0.74 wt%, respectively. The effect of the ball milling time on the morphological characterizations, thermal stability and hydrogenation/dehydrogenation properties of MgH2/7 wt% Mn3.6Ti2.4 powders were investigated. The powders obtained after 50 h of milling had spherical-like morphology and homogeneously with uniform composition close to the starting nominal composition. Moreover, this binary nanocomposite system possessed superior hydrogenation/dehydrogenation kinetics at 275 °C, as suggested by the short time required to absorb and desorb 5.3 wt% H2 within 2 and 8 min, respectively. At this temperature, the synthesized nanocomposite powders possessed excellent absorption/desorption cyclability of 1000 complete cycles within 1400 h. However, a minor degradation (∼0.3-0.4 wt% H2) in the hydrogen storage capacity was observed between 410 h and 1400 h of the cycle-life-time. This slight degradation took place due to the grain growth came off in the Mg/Mn3.6Ti2.4 grains. © 2015 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","Nanocrystalline MgH2 powders were prepared by reactive ball milling of pure Mg powders under 50 bar of a hydrogen gas atmosphere, using a high energy ball mill operated at room temperature. The end-product was doped with 7 wt% of Mn3.6Ti2.4 powders and then mechanically milled under a hydrogen gas atmosphere for 50 h, using a high energy ball mill for different ball milling time.",_
!331,"Hydrogen diffusion impacts the performance of solid-state hydrogen storage materials and contributes to the embrittlement of structural materials under hydrogen-containing environments. In atomistic simulations, the diffusion energy barriers are usually calculated using molecular statics simulations where a nudged elastic band method is used to constrain a path connecting the two end points of an atomic jump. This approach requires prior knowledge of the ""end points"". For alloy and defective systems, the number of possible atomic jumps with respect to local atomic configurations is tremendous. Even when these jumps can be exhaustively studied, it is still unclear how they can be combined to give an overall diffusion behavior seen in experiments. Here we describe the use of molecular dynamics simulations to determine the overall diffusion energy barrier from the Arrhenius equation. This method does not require information about atomic jumps, and it has additional advantages, such as the ability to incorporate finite temperature effects and to determine the pre-exponential factor. As a test case for a generic method, we focus on hydrogen diffusion in bulk aluminum. We find that the challenge of this method is the statistical variation of the results. However, highly converged energy barriers can be achieved by an appropriate set of temperatures, output time intervals (for tracking hydrogen positions), and a long total simulation time. Our results help elucidate the inconsistencies of the experimental diffusion data published in the literature. The robust approach developed here may also open up future molecular dynamics simulations to rapidly study diffusion properties of complex material systems in multidimensional spaces involving composition and defects. © 2016 American Chemical Society.","In atomistic simulations, the diffusion energy barriers are usually calculated using molecular statics simulations where a nudged elastic band method is used to constrain a path connecting the two end points of an atomic jump. The robust approach developed here may also open up future molecular dynamics simulations to rapidly study diffusion properties of complex material systems in multidimensional spaces involving composition and defects.",_
!332,"A computational platform is developed in the Modelica®language within the Dymola™ environment to provide a tool for the design and performance comparison of on-board hydrogen storage systems. The platform has been coupled with an open source library for hydrogen fueling stations to investigate the vehicular tank within the frame of a complete refueling system. The two technologies that are integrated in the platform are solid-state hydrogen storage in the form of metal hydrides and compressed gas systems. In this work the computational platform is used to compare the storage performance of two tank designs based on the tubular tank configuration with Ti1.1CrMn as the absorbing alloy. Results show that a shell and tube layout with metal hydride tubes of 2 mm inner diameter achieves the desired refueling time of 3 min and store a maximum of 3.1 kg of hydrogen in a 126 L tank, corresponding to a storage capacity four times larger than a tube-in-tube solution of the same size. The volumetric and gravimetric densities of the shell and tube are 2.46% and 1.25% respectively. The dehydriding ability of this solution is proven to withstand intense discharging conditions. © 2016 Hydrogen Energy Publications LLC","Results show that a shell and tube layout with metal hydride tubes of 2 mm inner diameter achieves the desired refueling time of 3 min and store a maximum of 3.1 kg of hydrogen in a 126 L tank, corresponding to a storage capacity four times larger than a tube-in-tube solution of the same size. The dehydriding ability of this solution is proven to withstand intense discharging conditions.",_
!333,"Modern metallurgy has a close collaboration with many other industrial fields and also with gas production industry. Using of hydrogen and nitrogen atmospheres in steel production and rolling show us metallurgy industry in a role of a big consumer of industrial gases. But from other side, metallurgy plants and companies always plays the role of suppliers for gas industry. This type of collaboration is not new, but in last decade's a development of powder metallurgy provides new possibility for two industries connection on the way of creation new types of energy storage systems, based on metal hydrides. Using of intermetallic compounds for hydrogen storage in solid form with the formation of chemical compounds (metal hydrides) with the possibility of sorption and desorption, provides energy storage systems with hydrogen densities greater than in the liquid and gaseous states. Hydrogen storage in intermetallic systems can be the most energy efficient and less energy consuming way of hydrogen storing in the near future. In present article the description of real applications and conditions of intermetallic systems, and possibilities to use metal compounds for creation energy storage systems and using that systems in real life is provided.","But from other side, metallurgy plants and companies always plays the role of suppliers for gas industry. Using of intermetallic compounds for hydrogen storage in solid form with the formation of chemical compounds (metal hydrides) with the possibility of sorption and desorption, provides energy storage systems with hydrogen densities greater than in the liquid and gaseous states.",_
!334,"The renewable resources related, for instance, to solar energies exhibit two main characteristics. They have no practical limits in regards to the efficiency and their various capture methods. However, their intermittence prevents any direct and immediate use of the resulting power. McPhy-Energy proposes solutions based on water electrolysis for hydrogen generation and storage on reversible metal hydrides to efficiently cover various energy generation ranges from MW h to GW h. Large stationary storage units, based on MgH2, are presently developed, including both the advanced materials and systems for a total energy storage from ∼70 to more than 90% efficient. Various designs of MgH2-based tanks are proposed, allowing the optional storage of the heat of the Mg-MgH2 reaction in an adjacent phase changing material. The combination of these operations leads to the storage of huge amounts of hydrogen and heat in our so-called adiabatic-tanks. Adapted to intermittent energy production and consumption from renewable sources (wind, sun, tide, etc.), nuclear over-production at night, or others, tanks distribute energy on demand for local applications (on-site domestic needs, refueling stations, etc.) via turbine or fuel cell electricity production. © 2013 Elsevier B.V. All rights reserved.","They have no practical limits in regards to the efficiency and their various capture methods. ), nuclear over-production at night, or others, tanks distribute energy on demand for local applications (on-site domestic needs, refueling stations, etc.)",_
!335,"Metal borohydrides offer high theoretical storage capacity for solid state hydrogen storage. This work is aimed at the mechanochemical synthesis of Yb(BH4)3 from LiBH4 and YbCl3. Different synthesis routes resulted in three new compounds, LiYb(BH 4)4-xClx, α-Yb(BH4) 3 and β-Yb(BH4)3. Their crystal structures have been determined from lab and synchrotron powder diffraction. LiYb(BH 4)4-xClx takes a primitive tetragonal structure with x = 1.0, a = 6.1729(3) Å and c = 12.4155(10) Å in the space group P42c (no. 112), α-Yb(BH4)3 a primitive cubic structure with a = 10.70715(15) Å in the space group Pa3 (no. 205), and β-Yb(BH4)3 a primitive cubic structure with a = 5.44223(3) Å in the space group Pm3m (no. 221). Thermal decomposition properties of the materials have been investigated by in situ synchrotron radiation powder X-ray diffraction, thermo gravimetric analysis/differential scanning calorimetry and temperature programmed desorption. The decomposition product, Yb(BH4)2-xClx, adopting a primitive tetragonal structure with space group P4 (no. 81) was formed after release of diborane gas, and x increases with increasing temperature. A deuterated sample of this compound was synthesized for powder neutron diffraction. Rietveld refinement gave x = 0.76, a = 6.74763(2) Å and c = 4.28368(2) Å. Another polymorph of Yb(BH4)2-xClx was synthesized, which adopts a primitive orthorhombic structure with space group Pbca (no. 61), where x = 0.3, a = 13.20997(20) Å, b = 8.26829(12) Å and c = 7.44532(11) Å. © The Royal Society of Chemistry 2013.","Thermal decomposition properties of the materials have been investigated by in situ synchrotron radiation powder X-ray diffraction, thermo gravimetric analysis/differential scanning calorimetry and temperature programmed desorption. Another polymorph of Yb(BH4)2-xClx was synthesized, which adopts a primitive orthorhombic structure with space group Pbca (no.",_
!336,"Hydrogen is conventionally stored as either a compressed gas or a cryogenic liquid. However, the lack of efficient storage materials has thus far critically limited the widespread adoption of hydrogen, and to overcome this limitation, a promising solid-state storage method is needed. Attractive lightweight metal-based materials for solid-state storage are characterized by the capability to reversibly store a large quantity of hydrogen and should meet or exceed the United States Department of Energy (DOE) on-board storage targets. However, the undesirable kinetic performances of metal hydrides as solid-state storage materials have hindered their practical use as hydrogen storage systems. The kinetic performances, which include the rate of hydrogen uptake or release, are among the most critical requirements of a storage system, and these performances can be determined using the hydrogen absorption and desorption rates. Thus, determining the relevant kinetics is required to supply sufficient amounts of hydrogen and to achieve fast refueling in the system. This review summarizes the kinetic performances and the efforts toward enhancing the hydrogen absorption/desorption kinetics of light metal-based materials. © 2016","However, the lack of efficient storage materials has thus far critically limited the widespread adoption of hydrogen, and to overcome this limitation, a promising solid-state storage method is needed. Attractive lightweight metal-based materials for solid-state storage are characterized by the capability to reversibly store a large quantity of hydrogen and should meet or exceed the United States Department of Energy (DOE) on-board storage targets.",_
!337,"Energy is one of the basic requirements in our daily lives. Daily activities such as cooking, cleaning, working on the computer and commuting to work are more or less dependent on energy. The world's energy demand is continuously increasing over the years due to the ever-increasing growth in the human population as well as economic development. At present, approximately 90% of energy demands are fulfilled by fossil fuels. With the rising demands of energy throughout the globe, it can be expected that the availability of fossil fuels is depleting at an alarming rate since fossil fuels are non-renewable sources of energy. In addition, fossil fuels are the main contributor of greenhouse gas emissions and therefore, they have a detrimental impact on human health and environment in the long term. Hence, there is a critical need to develop alternative sources of energy in replacement of fossil fuels. Hydrogen fuels have gained much interest among researchers all over the world since they are clean, non-toxic and renewable, making them suitable for use as substitutes for petroleum-derived fuels in vehicular applications. However, the greatest challenge in using hydrogen fuels lies in the development of hydrogen storage systems, especially for on-board applications. Hydrogen fuels can be stored in gaseous, liquid or solid states, and much effort has been made to develop hydrogen storage systems that are safe, cost-effective, environmental-friendly and more importantly, with high energy densities. Current technologies used for hydrogen storage include high-pressure compression at about 70 MPa, liquefaction at cryogenic temperatures (20 K) and absorption into solid state compounds. Among the three types of hydrogen storage technologies, the storage of hydrogen in solid state compounds appears to be the most feasible solution since it is a safer and more convenient method compared to high-pressure compression and liquefaction technologies. In this regard, metal hydrides are potential chemical compounds for solid-state hydrogen storage, and a large number of studies have been carried out to synthesize low-cost metal hydrides with low absorption/desorption temperatures, high gravimetric and volumetric hydrogen storage densities, good resistance to oxidation, good reversibility and cyclic ability, fast kinetics and reactivity, and moderate thermodynamic stability. In general, these studies have shown that the absorption/desorption properties of hydrogen can be improved by: (1) the addition of catalysts into the metal hydrides, (2) alloying the metal hydrides, or (3) nanostructuring. This review article is focused on the latest developments of metal hydrides for solid-state hydrogen storage applications, which will be of interest to scientists, researchers, and practitioners in this field. © 2016 Hydrogen Energy Publications LLC","Hydrogen fuels have gained much interest among researchers all over the world since they are clean, non-toxic and renewable, making them suitable for use as substitutes for petroleum-derived fuels in vehicular applications. Hydrogen fuels can be stored in gaseous, liquid or solid states, and much effort has been made to develop hydrogen storage systems that are safe, cost-effective, environmental-friendly and more importantly, with high energy densities.",_
!338,"Determining the thermal conductivity is crucial whenever heat transfer issues are considered which play a major role in many technological applications. However, various materials are sensitive to oxygen or moisture and, therefore, cannot be examined with commonly used equipment under ambient conditions. Here, we present a novel approach which combines the inert requirements of ambient-sensitive specimens with the flash method in which the apparatus, a Netzsch LFA 447 NanoFlash®, is placed under ambient conditions. A new measuring cell with flashtransparent windows was constructed which resembles a gas-tight specimen chamber. This device can be easily adapted to other apparatuses based on the flash method. The thermal conductivities of reference materials in inert and ambient conditions were examined in a temperature range from 25 to 275 °C. In general an excellent agreement was found. Further, the usability of this special sample cell is demonstrated for the investigation of the thermal conductivities of two complex hydride systems which are important for solid-state hydrogen storage applications. © Akadémiai Kiadó, Budapest, Hungary 2013.","Determining the thermal conductivity is crucial whenever heat transfer issues are considered which play a major role in many technological applications. However, various materials are sensitive to oxygen or moisture and, therefore, cannot be examined with commonly used equipment under ambient conditions.",_
!339,"Zr(BH4)4·8NH3 is considered to be a promising solid-state hydrogen-storage material, due to its high hydrogen density and low dehydrogenation temperature. However, the release of ammonia hinders its practical applications. To further reduce the dehydrogenation temperature and suppress ammonia release, here we investigated its hydrolysis process to evaluate its hydrogen generation performance. The results showed that the hydrolysis of Zr(BH4)4·8NH3 in water can generate about 1067 mL g-1 pure hydrogen in 240 min at 298 K without the release of diborane or ammonia impurity gases. With heat-assistance, the hydrogen generation rate can be significantly enhanced, and its activation energy was calculated to be 29.38 kJ mol-1. The hydrolysis mechanism was clarified. The results demonstrate that Zr(BH4)4·8NH3 may work as one promising hydrogen generation material. © The Royal Society of Chemistry 2017.","To further reduce the dehydrogenation temperature and suppress ammonia release, here we investigated its hydrolysis process to evaluate its hydrogen generation performance. The results demonstrate that Zr(BH4)4·8NH3 may work as one promising hydrogen generation material.",_
!340,"The state of the art of conversion reactions of metal hydrides (MH) with lithium is presented and discussed in this review with regard to the use of these hydrides as anode materials for lithium-ion batteries. A focus on the gravimetric and volumetric storage capacities for different examples from binary, ternary and complex hydrides is presented, with a comparison between thermodynamic prediction and experimental results. MgH2 constitutes one of the most attractive metal hydrides with a reversible capacity of 1480 mA·h·g-1 at a suitable potential (0.5 V vs Li+/Li0) and the lowest electrode polarization (<0.2 V) for conversion materials. Conversion process reaction mechanisms with lithium are subsequently detailed for MgH2, TiH2, complex hydrides Mg2MHx and other Mg-based hydrides. The reversible conversion reaction mechanism of MgH2, which is lithium-controlled, can be extended to others hydrides as: MHx + xLi+ + xe- in equilibrium with M + xLiH. Other reaction paths-involving solid solutions, metastable distorted phases, and phases with low hydrogen content-were recently reported for TiH2 and Mg2FeH6, Mg2CoH5 and Mg2NiH4. The importance of fundamental aspects to overcome technological difficulties is discussed with a focus on conversion reaction limitations in the case of MgH2. The influence of MgH2 particle size, mechanical grinding, hydrogen sorption cycles, grinding with carbon, reactive milling under hydrogen, and metal and catalyst addition to the MgH2/carbon composite on kinetics improvement and reversibility is presented. Drastic technological improvement in order to the enhance conversion process efficiencies is needed for practical applications. The main goals are minimizing the impact of electrode volume variation during lithium extraction and overcoming the poor electronic conductivity of LiH. To use polymer binders to improve the cycle life of the hydride-based electrode and to synthesize nanoscale composite hydride can be helpful to address these drawbacks. The development of high-capacity hydride anodes should be inspired by the emergent nano-research prospects which share the knowledge of both hydrogen-storage and lithium-anode communities. © 2015 Aymard et al.","The reversible conversion reaction mechanism of MgH2, which is lithium-controlled, can be extended to others hydrides as: MHx + xLi+ + xe- in equilibrium with M + xLiH. Drastic technological improvement in order to the enhance conversion process efficiencies is needed for practical applications.",_
!341,"A new hydrogen storage material, a hydrolysis product of sodium borohydride (HPSB) which shows good reversible capacities for hydrogen storage at 150 °C under vacuum condition after absorbing hydrogen during 5 min at room temperature under 3 MPa hydrogen pressure, is reported. It has been shown that both changing the catalysts for NaBH4 hydrolysis and adding catalysts directly into HPSB are two very effective methods to further improve HPSB hydrogen storage capacity. The dehydrogenation of HPSB-Y2O3 and TiO2-doped HPSB-Y2O3 were found to reach 2.4 wt.% and 4.6 wt.%, respectively. Importantly, the reversible dehydrogenation ability of HPSB-Y2O3 does not decrease after successive cycles. In comparison, the reversible dehydrogenation of HPSB-CeO2 is higher and reaches 5.9 wt.% at 150 °C after hydrogen adsorption for 5 min at room temperature under 3 MPa hydrogen pressure. Compared to other hydrogen storage materials, especially solid-state hydrogen storage, these materials show several advantages in their capacity and, especially, their ability to operate under mild conditions. © 2015 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","Importantly, the reversible dehydrogenation ability of HPSB-Y2O3 does not decrease after successive cycles. Compared to other hydrogen storage materials, especially solid-state hydrogen storage, these materials show several advantages in their capacity and, especially, their ability to operate under mild conditions.",_
!342,"Attempts to synthesize solvent-free MgB12H12 by heating various solvated forms (H2O, NH3, and CH 3OH) of the salt failed because of the competition between desolvation and dehydrogenation. This competition has been studied by thermogravimetric analysis (TGA) and temperature-programmed desorption (TPD). Products were characterized by IR, solution- and solid-state NMR spectroscopy, elemental analysis, and single-crystal or powder X-ray diffraction analysis. For hydrated salts, thermal decomposition proceeded in three stages, loss of water to form first hexahydrated then trihydrated, and finally loss of water and hydrogen to form polyhydroxylated complexes. For partially ammoniated salts, two stages of thermal decomposition were observed as ammonia and hydrogen were released with weight loss first of 14% and then 5.5%. Thermal decomposition of methanolated salts proceeded through a single step with a total weight loss of 32% with the release of methanol, methane, and hydrogen. All the gaseous products of thermal decomposition were characterized by using mass spectrometry. Residual solid materials were characterized by solid-state 11B magic-angle spinning (MAS)NMR spectroscopy and X-ray powder diffraction analysis by which the molecular structures of hexahydrated and trihydrated complexes were solved. Both hydrogen and dihydrogen bonds were observed in structures of [Mg(H2O)6B12H12]η6H 2O and [Mg(CH3OH)6B12H 12]η6CH3OH, which were determined by single-crystal X-ray diffraction analysis. The structural factors influencing thermal decomposition behavior are identified and discussed. The dependence of dehydrogenation on the formation of dihydrogen bonds may be an important consideration in the design of solid-state hydrogen storage materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.",This competition has been studied by thermogravimetric analysis (TGA) and temperature-programmed desorption (TPD). All the gaseous products of thermal decomposition were characterized by using mass spectrometry.,_
!343,"One of the current main challenges in green-power storage and smart grids is the lack of effective solutions for accommodating the unbalance between renewable energy sources-offering intermittent electricity supply - and a variable electricity demand. Integrating intermittent renewable energy sources by safe and cost-effective energy storage systems is today achievable. Coupled with electrolizers, high-capacity solid-state storage of green-hydrogen is practicable to sustain integration, monitoring and control of large quantity of GWh from renewable generation. The 23.9 MLN Euros INGRID European large demonstrative project started in July 2012 combines magnesium-based material solid-state hydrogen storage systems with advanced ICT technologies to intelligently interconnect miscellaneous energy networks (i.e. electricity and gas) and safely delivering green-hydrogen to various existing or forthcoming markets. One solution INGRID project addresses is an off-grid utility to store renewable electricity captured from wind sources to refill full-battery electric cars. © Copyright 2015 by The Minerals, Metals & Materials Society. All rights reserved.",The 23.9 MLN Euros INGRID European large demonstrative project started in July 2012 combines magnesium-based material solid-state hydrogen storage systems with advanced ICT technologies to intelligently interconnect miscellaneous energy networks (i.e. electricity and gas) and safely delivering green-hydrogen to various existing or forthcoming markets. One solution INGRID project addresses is an off-grid utility to store renewable electricity captured from wind sources to refill full-battery electric cars.,_
!344,"The development of highly efficient hydrogen storage materials is one of the main challenges that must be tackled in a widely expected hydrogen economy. Physisorption in porous materials with high surface areas and chemisorption in hydrides are the two main options for solid state hydrogen storage, and both options possess their inherent advantages and drawbacks. In this work, recent progress towards porous carbon-based materials for hydrogen storage is analyzed and reviewed. The hydrogen storage performance of plain porous carbons, metal-supported porous carbons and porous carbons confined hydrides is summarized. Some strategies for effectively controlling the hydrogen storage capacity and tuning the hydrogen adsorption enthalpy for porous carbon materials via appropriate manipulation of surface area, pore volume and pore size are discussed in detail. The new development of porous carbon-based materials for hydrogen storage is particularly emphasized. © 2013 The Royal Society of Chemistry.","In this work, recent progress towards porous carbon-based materials for hydrogen storage is analyzed and reviewed. Some strategies for effectively controlling the hydrogen storage capacity and tuning the hydrogen adsorption enthalpy for porous carbon materials via appropriate manipulation of surface area, pore volume and pore size are discussed in detail.",_
!345,"Electrochemical storage of hydrogen in activated carbon (aC) electrodes as part of a reversible fuel cell offers a potentially attractive option for storing surplus electrical energy from inherently variable solar and wind energy resources. Such a system – which we have called a proton flow battery – promises to have a roundtrip energy efficiency comparable to lithium ion batteries, while having higher gravimetric and volumetric energy densities. Activated carbons with high internal surface area, high pore volume, light weight and easy availability have attracted considerable research interest as a solid-state hydrogen storage medium. This paper compares the physical characteristics and hydrogen storage capacities of four activated carbon (aC) electrodes made from brown coal. The fabrication methods for these samples are explained. Their proton conductivity was measured using electrochemical impedance spectroscopy and their hydrogen storage capacity by galvanostatic charging and discharging in a three-electrode electrolytic cell with 1 mol sulphuric acid as electrolyte at atmospheric pressure and room temperature. The highest hydrogen storage capacity obtained was 1.29 wt%, which compares favourably with metal hydrides used in commercially available solid-state hydrogen storages. Finally, the relation between the hydrogen storage capacity of the samples and their Dubinin-Radushkevich surface area (calculated by the CO2 adsorption method) was investigated. The results point the way towards selecting high-performing electrodes for proton flow batteries and signal the potential competitiveness of this energy storage technology. © 2016 Hydrogen Energy Publications LLC",Electrochemical storage of hydrogen in activated carbon (aC) electrodes as part of a reversible fuel cell offers a potentially attractive option for storing surplus electrical energy from inherently variable solar and wind energy resources. This paper compares the physical characteristics and hydrogen storage capacities of four activated carbon (aC) electrodes made from brown coal.,_
!346,"In high temperature proton exchange membrane (HT-PEM) fuel cells, waste heat at approximately 160 °C is produced, which can be used for thermal integration of solid state hydrogen storage systems. In the present study, an HT-PEM fuel cell stack (400 W) with direct liquid cooling is characterized and coupled to a separately characterized sodium alanate storage tank (300 g material). The coupled system is studied in steady state for 20 min operation and all relevant heat flows are determined. Even though heat losses at that specific power and temperature level cannot be completely avoided, it is demonstrated that the amount of heat transferred from the fuel cell stack to the cooling liquid circuit is sufficient to desorb the necessary amount of hydrogen from the storage tank. Furthermore, it is shown that the reaction rate of the sodium alanate at 160 °C and 1.7 bar is adequate to provide the hydrogen to the fuel cell stack. Based on these experimental investigations, a set of recommendations is given for the future design and layout of similar coupled systems. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","In high temperature proton exchange membrane (HT-PEM) fuel cells, waste heat at approximately 160 °C is produced, which can be used for thermal integration of solid state hydrogen storage systems. The coupled system is studied in steady state for 20 min operation and all relevant heat flows are determined.",_
!347,"Hydrogen storage is a key research area where considerable international effort is concentrated. Thus, the chapter focuses on aspects of hydrogen storage options, be it liquid, compressed, cryo-comperssed or materials based on the physical and chemical ways. It includes information on emerging mechanisms for reversible storage of hydrogen. Hydrogen storage options have several critical features that have to be solved. In general, the weight, volume and cost of hydrogen storage systems is too high and the durability of hydrogen storage systems is inadequate. High-pressure cylinders for compressed gas and other high-pressure elements limit the choice of construction materials and fabrication techniques within weight, volume, performance and cost constraints. Furthermore, hydrogen refuelling times are too long. Research is also needed on improving hydrogen discharge kinetics and simplifying the reactor required for discharging hydrogen on board the vehicle, such as the volume, weight and operation to name a few. For metal hydrides weight, system volume and refuelling time are the primary issues. Safe and compact hydrogen storage in a solid medium could be considered to be superior to liquid or compressed storage provided that a suitable material is found to fulfil the requirements from US DOE in terms of both gravimetric and volumetric capacities as well as favourable hydrogen loading/deloading characteristics. The latter is particularly important if the hydrogen is to be utilized within the operational envelope of PEM fuel cells. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA. All rights reserved.","For metal hydrides weight, system volume and refuelling time are the primary issues. Safe and compact hydrogen storage in a solid medium could be considered to be superior to liquid or compressed storage provided that a suitable material is found to fulfil the requirements from US DOE in terms of both gravimetric and volumetric capacities as well as favourable hydrogen loading/deloading characteristics.",_
!348,[No abstract available],[No abstract available],_
!349,"Hydrogen-based power systems require safe, efficient and robust hydrogen storage solutions. In this regard, metal hydrides become increasingly important because of their extremely high volumetric hydrogen capacity and their moderate operation pressures. The loading and unloading dynamics of hydride-based hydrogen tanks is mainly influenced by the intrinsic hydrogen sorption kinetics of the storage material as well as by the heat and gas transport properties of the hydride bed. In this contribution, pelletized composites of the room-temperature hydrogen storage material Hydralloy C52 (AB 2-type) with expanded natural graphite (ENG) are discussed in view of high-dynamic hydrogen solid-state storage applications. Powdery Hydralloy C52 is blended with up to 12.5 wt.% ENG. The blend is pelletized at compaction pressures up to 600 MPa. The Hydralloy-ENG pellets exhibit an increased effective thermal conductivity and provide an increased volumetric H2 storage capacity compared to loose powders. The hydrogenation behavior at different temperatures and for various hydrogenation-dehydrogenation cycles is discussed. Furthermore, the stability of the pellets throughout cyclic hydrogenation is evaluated. High gas permeability in radial direction and sufficient thermal conductivity in combination with a stable pellet structure underline the potential of Hydralloy-ENG composites for hydrogen storage applications with high loading dynamics. © 2012 Elsevier Ltd. All rights reserved.",The hydrogenation behavior at different temperatures and for various hydrogenation-dehydrogenation cycles is discussed. High gas permeability in radial direction and sufficient thermal conductivity in combination with a stable pellet structure underline the potential of Hydralloy-ENG composites for hydrogen storage applications with high loading dynamics.,_
!350,"Current state-of-the-art methods consist of containing high-pressure compressed hydrogen in composite cylinders, with solid-state hydrogen storage materials an alternative that could improve on storage performance by enhancing volumetric densities. A new strategy that uses cryogenic temperatures to load hydrogen (cryocharging) is proposed and analysed in this work, comparing densities and final storage pressures for empty cylinders and containers with the high-surface area materials MIL-101 (Cr) and AX-21. Results show cryocharging as a viable option, as it can substantially lower the charging (at 77 K) and final pressures (at 298 K) for the majority of the cases considered. Kinetics are an equally important requirement for hydrogen storage systems, so the effective diffusivities at these conditions for both materials were calculated, and showed values comparable to the ones estimated in metal-organic frameworks and zeolites from quasielastic neutron scattering and molecular simulations. High-surface area materials tailored for hydrogen storage are a promising route for storage in mobile applications and results show that cryocharging is a promising strategy for hydrogen storage systems, since it increases volumetric densities and avoids energy penalties of operating at high pressures and/or low temperatures. © 2015 Elsevier Ltd.","Current state-of-the-art methods consist of containing high-pressure compressed hydrogen in composite cylinders, with solid-state hydrogen storage materials an alternative that could improve on storage performance by enhancing volumetric densities. High-surface area materials tailored for hydrogen storage are a promising route for storage in mobile applications and results show that cryocharging is a promising strategy for hydrogen storage systems, since it increases volumetric densities and avoids energy penalties of operating at high pressures and/or low temperatures.",_
!351,"The crystal structure of diethylaminoalane, [H2Al - N(C2H5)2]2, was determined by X-ray powder diffraction in conjunction with DFT calculations. Diethylaminoalane crystallizes in the monoclinic space group P21/c with a = 7.4020 (2), b = 12.9663 (3), c = 7.2878 (2) Å and β = 90.660 (2)° at 293 K. The crystal structure was confirmed by DFT calculations and Raman spectroscopy. The molecular structure of diethylaminoalane consists of dimers of [H2Al - N(CH2CH3)2] in which an Al2N2 four-membered ring is formed by a center of inversion. Such an arrangement of the aminoalane moieties in the crystal structure is well known for this class of compound, as shown by the comparison with ethylmethylaminoalane and diisopropylaminoalane.The crystal structure of diethylaminoalane, [H2Al - N(C2H5)2]2, was determined by X-ray powder diffraction, geometry optimization by density functional theory (DFT) and Raman spectroscopy. The DFT calculations were validated by calculating the ground state structures of two known aminoalanes while the Raman spectrum of diethylaminoalane was measured and compared to the simulated ones. Furthermore, the crystal structure of diethylaminoalane is compared with chemically and structurally similar compounds. © International Union of Crystallography, 2016.","The crystal structure of diethylaminoalane, [H2Al - N(C2H5)2]2, was determined by X-ray powder diffraction in conjunction with DFT calculations. Furthermore, the crystal structure of diethylaminoalane is compared with chemically and structurally similar compounds.",_
!352,"Y(BH4)3 is one of the candidates for solid-state hydrogen storage, which contains 9.06 wt% of hydrogen. In this study, the thermal properties of Y(BH4)3 synthesized via two different methods are extensively examined. One method relies on the solid-solid metathesis reaction between LiBH4 and YCl3, and the other method is the gas-solid reaction between B2H6 and YH 3. The two samples are studied by differential scanning calorimetry, thermogravimetry, and X-ray diffraction. They exhibit distinctly different polymorphic phase transformation and melting. It turns out that the side product LiCl in the metathesis reaction, which has been regarded as being inert, shifts the melting point and promotes the formation of YB4 during decomposition. Differential scanning calorimetry and in situ X-ray diffraction data indicate that the addition of LiBH4 to Y(BH4) 3 induces co-melting as is found in the cases of LiBH 4-Ca(BH4)2 or LiBH4-Mg(BH 4)2. Melt infiltration of Y(BH4)3 into mesoporous carbon cage confirms such melting behavior. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","In this study, the thermal properties of Y(BH4)3 synthesized via two different methods are extensively examined. The two samples are studied by differential scanning calorimetry, thermogravimetry, and X-ray diffraction.",_
!353,"LiBH4–MgH2 composite is one of the most promising solid-state hydrogen storage materials because it exhibits good reversibility as well as lower total reaction enthalpy. Nevertheless, its utilization for onboard hydrogen storage is hindered by poor reaction kinetics. In order to improve the kinetics, pre-milled multi-walled carbon nanotubes (MWCNTs) were added to LiBH4–MgH2 composite. Thereafter, we measured in situ X-ray diffraction patterns of LiBH4–MgH2 and LiBH4–MgH2-MWCNTs composites at various temperatures to study the decomposition process. The pre-milled MWCNTs played an effective role in reducing the MgH2 and LiBH4 dehydrogenation temperatures. In addition, MgH2 grain growth was inhibited by the formation of Mg in both the samples, and the inhibition started at a temperature lower by ∼50 °C in the composite with MWCNTs compared with the LiBH4–MgH2 composite. © 2016 Hydrogen Energy Publications LLC","Nevertheless, its utilization for onboard hydrogen storage is hindered by poor reaction kinetics. Thereafter, we measured in situ X-ray diffraction patterns of LiBH4–MgH2 and LiBH4–MgH2-MWCNTs composites at various temperatures to study the decomposition process.",_
!354,"Mechanochemistry has played an important role in the synthesis of many novel compounds, in particular within the field of materials for solid state hydrogen storage applications. This work investigates reactive milling of ethane 1,2-di-amineborane (EDAB) and sodium hydride which yields the evolution of one equivalent of hydrogen and the formation of a novel compound (named NaEDAB) as evidenced by X-ray diffraction analyses. We postulate for this compound the chemical formula NaB2C2N2H13. The thermolysis of NaEDAB below 400 °C releases about 8 wt.% pure hydrogen, without producing foaming. Moreover, sodium addition significantly modifies hydrogen desorption enthalpies, giving rise to milder exothermic H2 release at moderate temperatures with respect to neat EDAB, as well as an endothermic desorption process at higher temperature. This result opens novel and promising perspectives towards the reversible hydrogenation of these compounds. © 2014 Hydrogen Energy Publications, LLC.","Moreover, sodium addition significantly modifies hydrogen desorption enthalpies, giving rise to milder exothermic H2 release at moderate temperatures with respect to neat EDAB, as well as an endothermic desorption process at higher temperature. This result opens novel and promising perspectives towards the reversible hydrogenation of these compounds.",_
!355,"A 2-D mathematical model is developed for predicting the minimum charging/discharging time of the metal hydride based hydrogen storage device by varying the number of cooling tubes embedded in it. This study is extended to 3-D mathematical model for predicting the hydriding and dehydriding characteristics of LmNi4.91Sn0.15 based hydrogen storage device with 60 embedded cooling tubes (ECT) using COMSOL Multiphysics 4.3. The performance of the hydrogen storage device during hydriding/dehydriding process is presented for different supply pressure (10-35 bar), hot fluid temperature (30-60 °C) and effective thermal conductivity of hydride bed (0.2-2.5 W/(m·K)). It is observed that the rate of heat transfer and the hydriding and dehydriding rates are enhanced when the number of ECT is increased from 24 to 70. For the reactor with 60 ECT, the rate of hydrogen absorption is rapid for the supply pressure of 35 bar and hydride bed effective thermal conductivity of 2.5 W/(m·K). The numerically predicted hydrogen storage capacity (wt%) and amount of hydrogen desorbed (wt%) are compared with experimental data and found a good accord between them. © 2014 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","This study is extended to 3-D mathematical model for predicting the hydriding and dehydriding characteristics of LmNi4.91Sn0.15 based hydrogen storage device with 60 embedded cooling tubes (ECT) using COMSOL Multiphysics 4.3. The performance of the hydrogen storage device during hydriding/dehydriding process is presented for different supply pressure (10-35 bar), hot fluid temperature (30-60 °C) and effective thermal conductivity of hydride bed (0.2-2.5 W/(m·K)).",_
!356,"TiFe, a potential candidate for solid-state hydrogen storage, does not absorb hydrogen without a sophisticated activation process because of severe oxidation. This study shows that nanostructured TiFe becomes active by high-pressure torsion (HPT) and is not deactivated even after storage for several hundred days in the air. Surface segregation and formation of Fe-rich islands and cracks occur after HPT. The Fe-rich islands are suggested to act as catalysts for hydrogen dissociation and cracks and nanograin boundaries act as pathways to transport hydrogen through the oxide layer. Rapid atomic diffusion by HPT is responsible for enhanced surface segregation and hydrogen transportation. © 2013 AIP Publishing LLC.",This study shows that nanostructured TiFe becomes active by high-pressure torsion (HPT) and is not deactivated even after storage for several hundred days in the air. Rapid atomic diffusion by HPT is responsible for enhanced surface segregation and hydrogen transportation.,_
!357,"Abstract Heat exchanger design plays a significant role in the performance of solid state hydrogen storage device. In the present study, a cylindrical hydrogen storage device with an embedded annular heat exchanger tube with radial circular copper fins, is considered. A 3-D mathematical model of the storage device is developed to investigate the sorption performance of metal hydride (MH). A prototype of the device is fabricated for 1 kg of MH alloy, LaNi5, and tested at constant supply pressure of hydrogen, validating the simulation results. Absorption characteristics of storage device have been examined by varying different operating parameters such as hydrogen supply pressure and cooling fluid temperature and velocity. Absorption process is completed in 18 min when these parameters are 15 bar, 298 K and 1 m/s respectively. A study of geometric parameters of copper fins (such as perforation, number and thickness of fin) has been carried out to investigate their effects on absorption process. © 2015 Hydrogen Energy Publications, LLC.","Abstract Heat exchanger design plays a significant role in the performance of solid state hydrogen storage device. Absorption process is completed in 18 min when these parameters are 15 bar, 298 K and 1 m/s respectively.",_
!358,"Today, it is important to develop more efficient combustion technology in order to save energy and reduce air pollution. In this paper, a novel technology of hydrogen-gasoline compound fuel is developed. Hydrogen gas is released from solid state hydrogen storage tank and then mixed with the incoming gasoline. The intake valve in manifold sucks the hydrogen-gasoline compound fuel into the cylinder for combustion. A series of performance test is conducted by motorcycle chassis dynamometers. The results reveal that this technology can increase the power and torque, and decrease fuel consumption per kilo-power due to promote combustion efficiency. In addition, the oil temperature and spark plug temperature increase. This technique can reduce CO and HC, but increase CO2 and NOx. This technique can achieve energy saving and environment-friendly purpose. © 2015 International Conference on Liquid Atomization and Spray Systems. All rights reserved.","In this paper, a novel technology of hydrogen-gasoline compound fuel is developed. A series of performance test is conducted by motorcycle chassis dynamometers.",_
!359,Mg–Ni alloys are among the most promising candidates for solid-state hydrogen storage systems. This paper reveals the effect of Na doping in accelerating initial hydrogen uptake in Mg–Ni alloys using in-situ Synchrotron X-ray powder diffraction. A minimum concentration of approximately 0.2 wt.% Na must be achieved for the alloys to show reasonably fast hydriding kinetics. Surface analysis shows that a Na-modified Mg–Ni surface facilitates the chemisorption and dissociation of hydrogen molecules in the early stage of hydriding as evidenced by a rapid formation of the saturated hydrogen solid solution Mg2NiH0.3 from the original Mg2Ni. The subsequent hydrogen absorption is based on a mechanism of nucleation and growth of MgH2 where a high density of dislocations develops ahead of the growing hydride-metal interface. © 2016 Hydrogen Energy Publications LLC,Mg–Ni alloys are among the most promising candidates for solid-state hydrogen storage systems. A minimum concentration of approximately 0.2 wt.% Na must be achieved for the alloys to show reasonably fast hydriding kinetics.,_
!360,"In this paper, a thermodynamical model of a porous media made of one or two solid phases α and β (depending on the hydrogen concentration) and one gas phase H2 is presented. As an extension of previous works performed by Gondor and Lexcellent (Int J Hydrog Energy 34(14):5716–5725, doi:10.1016/j.ijhydene.2009.05.070, 2009), our attention is paid to the identification of the vectorial displacement and by consequence to the stress and strain states in every point of the tank. This study allows a safe design of the reservoir. In front of the complexity of the problem to solve, a synthesis and a table of unknowns, constants, and parameters will ease the reader understanding. The problem is restricted to the isotropic elastic behavior of the solid phases. A great ingredient of the investigation is the phase transformation between the two phases α and β. © 2014, Springer-Verlag Berlin Heidelberg.","In this paper, a thermodynamical model of a porous media made of one or two solid phases α and β (depending on the hydrogen concentration) and one gas phase H2 is presented. This study allows a safe design of the reservoir.",_
!361,"Dehydrogenation kinetics and reversibility of LiAlH4–LiBH4 doped with Ti-based additives (TiCl3 and Ti-isopropoxide), multiwall carbon nanotubes (MWCNT), and MWCNT impregnated with Ti-based additives are proposed. Reduction of dehydrogenation temperature as well as improvements of kinetics and reversibility, especially decomposition of thermodynamically stable hydride (LiBH4) is obtained from the samples doped with Ti-isopropoxide and MWCNT. This can be due to the fact that the formations of LixAl(1−x)B2 and LiH-Al containing phase during dehydrogenation favor decomposition of LiH, leading to increment of hydrogen capacity, and stabilization of boron in solid state, resulting in improvement of reversibility. Besides, the curvatures and thermal conductivity of MWCNT benefit hydrogen diffusion and heat transfer during de/rehydrogenation. Nevertheless, deficient hydrogen content reversible is observed in all samples due to the irreversible of LiAlH4 and/or Li3AlH6 as well as the formation of stable phase (Li2B12H12) during de/rehydrogenation. © 2016 Elsevier Ltd","Reduction of dehydrogenation temperature as well as improvements of kinetics and reversibility, especially decomposition of thermodynamically stable hydride (LiBH4) is obtained from the samples doped with Ti-isopropoxide and MWCNT. Nevertheless, deficient hydrogen content reversible is observed in all samples due to the irreversible of LiAlH4 and/or Li3AlH6 as well as the formation of stable phase (Li2B12H12) during de/rehydrogenation.",_
!362,"Two Ti-V-Mn BCC-Laves phase alloys with the nominal composition Ti 0.5V0.5±xMn (x = -0.04 and 0.01), were synthesised by arc melting. This compositional difference resulted in different compositions and unit cell volumes for the C14 Laves phase. Ti 0.47V0.46Mn and Ti0.50V0.51Mn demonstrated reversible hydrogen sorption capacities of 1.53 and 1.56 ± 0.05 wt.% (at 120 bar H2 at 303 K) respectively, however, the change in composition results in a small change in the enthalpy of hydride decomposition, and a significant change in plateau pressure and hysteresis. This may allow for the plateau pressure to be tuned to meet the requirements of different solid-state hydrogen storage applications. © 2013 Elsevier B.V. All rights reserved.","Two Ti-V-Mn BCC-Laves phase alloys with the nominal composition Ti 0.5V0.5±xMn (x = -0.04 and 0.01), were synthesised by arc melting. This compositional difference resulted in different compositions and unit cell volumes for the C14 Laves phase.",_
!363,"Hydrogen, which has the characteristics of clean, efficient and renewable utilization, was one of the promising new energies in the future. The safe, efficient and economical hydrogen storage was the key technique for the large scale application of hydrogen energy, relative to the high pressure gaseous hydrogen storage and liquid hydrogen storage, the solid state hydrogen storage technology could store hydrogen in materials by forming solid solution or hydrides, which was regarded as the most promising technique because of its good safety and high energy density. LiBH4 was the typical representative of high capacity of hydrogen storage material and research hot spot because of its theory capacity of 18.5%(mass fraction), far from overtaking hydrogen source system load weight greater than 5% of hydrogen storage capacity requirements, but it was faced with serious thermodynamics and kinetics problems. Starting from improving performance of the absorption and releasing LiBH4 hydrogen, the research progress of hydrogen storage technology and hydrogen storage material was analyzed, and the major measures taken in recent years were reviewed, such as adding reactants to form a composite hydrogen storage system, the appropriate doping anion and cation to change the electronegativity, adding catalyst, reducing the grain size and nanometer filling method. The emphases were focused on the mechanisms, hydrogen storage capacity, temperature and condition thermodynamics and kinetics. High capacity LiBH4 hydrogen storage materials were the key to practical onboard hydrogen source system, the focus of future research was to develop method and system of quick hydrogen absorption, a large amount and reversibility of hydrogen absorption and desorption, and room temperature operation.","The safe, efficient and economical hydrogen storage was the key technique for the large scale application of hydrogen energy, relative to the high pressure gaseous hydrogen storage and liquid hydrogen storage, the solid state hydrogen storage technology could store hydrogen in materials by forming solid solution or hydrides, which was regarded as the most promising technique because of its good safety and high energy density. High capacity LiBH4 hydrogen storage materials were the key to practical onboard hydrogen source system, the focus of future research was to develop method and system of quick hydrogen absorption, a large amount and reversibility of hydrogen absorption and desorption, and room temperature operation.",_
!364,"Hydrogen storage is an important aspect to enable the so-called hydrogen economy. Mg-Ni alloys are among the most promising candidates for solid-state hydrogen storage systems yet many questions remain unanswered regarding the hydriding/dehydriding mechanism of the alloys. Mg2NiH4 particularly has received much attention both for its potential as a hydrogen storage medium and also exhibits interesting properties relating to its different polymorphs. Here, the dehydriding mechanism in bulk Mg2NiH4 is investigated using in-situ ultra-high voltage transmission electron microscopy (TEM) combined with Synchrotron powder X-ray diffraction (XRPD) and differential scanning calorimetry (DSC). We find that the hydrogen release is based on a mechanism of nucleation and growth of Mg2NiHx (x∼0–0.3) solid solution grains and is greatly enhanced in the presence of crystal defects occurring as a result of the polymorphic phase transformation. Also importantly, with atomic resolution TEM imaging a high density of stacking faults is identified in the dehydrided Mg2NiHx (x∼0–0.3) lattices. © 2016 Elsevier B.V.","Here, the dehydriding mechanism in bulk Mg2NiH4 is investigated using in-situ ultra-high voltage transmission electron microscopy (TEM) combined with Synchrotron powder X-ray diffraction (XRPD) and differential scanning calorimetry (DSC). Also importantly, with atomic resolution TEM imaging a high density of stacking faults is identified in the dehydrided Mg2NiHx (x∼0–0.3) lattices.",_
!365,"A numerical study was carried out to address the practical aspects of hydrogen absorption and desorption process in a long tubular LaNi5 metal hydride tank (MHT) integrated with Rubitherm phase change material (PCM) jacket for hydrogen supplying of PEM fuel cell. Different H2 supply pressures (p = 10, 15 and 20 bar), different discharge pressures (p = 1.5, 1.75 and 2 bar) and metal hydride bed porosities (0.4, 0.5 and 0.6) were rigorously analyzed to report their influences on transient and local temperature distributions across H2-MHT system and PCM jacket. The time-dependent changes of hydrogen to metal (H/M) ratio and PCM melt fraction were also investigated until they reach equilibrium. It was found that system temperature, PCM melt fraction and H/M ratio reach steady state with different rates, such that systems with higher supply pressure in absorption, lower discharge pressure in desorption and higher bed porosity approach steady state faster. Up to the steady state, 64%, 79% and 91% of the initial volume of solid PCM liquefies in absorption and 67%, 83% and 95% of liquid PCM solidifies in desorption for bed porosities of 0.6, 0.5 and 0.4, respectively. The MHT is charged with hydrogen much faster under high supply pressures. Also, it is discharged much faster under lower discharge pressure. Inserting metal foam in the PCM jacket enhances the thermal conductivity, and significantly reduces the charging and discharging time. © 2016 Hydrogen Energy Publications LLC.","The time-dependent changes of hydrogen to metal (H/M) ratio and PCM melt fraction were also investigated until they reach equilibrium. It was found that system temperature, PCM melt fraction and H/M ratio reach steady state with different rates, such that systems with higher supply pressure in absorption, lower discharge pressure in desorption and higher bed porosity approach steady state faster.",_
!366,"Abstract Evaluation of the performances of hydrogen storage systems accommodating solid H storage materials should include characteristics on their reversible hydrogen storage capacity, operating pressures and temperatures, packing densities, and heat effects of hydrogen uptake and release. We have conducted a performance evaluation of the systems accumulating 5 kg of hydrogen in a containment of cylindrical geometry filled with a solid H storage material including such hydrides and reactive hydride composites as AlH3, MgH2, ""low-temperature"" (inter)metallic hydrides, NaAlH4, Na3AlH6, LiBH4 + MgH2, and MOFs. The analysis yielded gravimetric and volumetric H storage capacities, and energy efficiencies of hydrogen stores. We conclude that the weight efficiency of hydrogen stores, apart from the gravimetric H storage capacity of the material, is greatly affected by its packing density, and by the pressure-temperature conditions which determine type and dimensions of the containment. The materials with low heat effects of H exchange, operating close to the ambient conditions, should be targeted in the course of the development of new hydrogen stores as offering the best energy efficiency of their operation. © 2014 Elsevier B.V.","Abstract Evaluation of the performances of hydrogen storage systems accommodating solid H storage materials should include characteristics on their reversible hydrogen storage capacity, operating pressures and temperatures, packing densities, and heat effects of hydrogen uptake and release. We have conducted a performance evaluation of the systems accumulating 5 kg of hydrogen in a containment of cylindrical geometry filled with a solid H storage material including such hydrides and reactive hydride composites as AlH3, MgH2, ""low-temperature"" (inter)metallic hydrides, NaAlH4, Na3AlH6, LiBH4 + MgH2, and MOFs.",_
!367,"Magnesium hydride is widely known as an interesting candidate for solid-state hydrogen storage. However it is too stable and does not desorb hydrogen at ambient conditions. Although MgH2 suffers from slow kinetics, its hydrogenation kinetics can be significantly improved by addition of catalysts and/or decreasing the grain size. Reducing the thermodynamic stability of MgH2 is now the main challenging task. In this study, 21 different elements were added to magnesium in atomic scale by using the High-Pressure Torsion (HPT) technique and different kinds of nanostructured intermetallics and new metastable or amorphous phases were synthesized after HPT (Mg17Al12, MgZn, MgAg, Mg2In, Mg2Sn, etc.) or after post-HPT heat treatment (MgB2, Mg2Si, Mg2Ni, Mg2Cu, MgCo, Mg2Ge, Mg2Pd, etc.). In most of the compounds, the desorption temperature decreases by addition of elements, even though that the ternary hydrides are formed only in limited systems such as Mg-Ni and Mg-Co. Appreciable correlations were achieved between the theoretical binding energies obtained by first-principles calculations and the experimental dehydrogenation temperatures. These correlations can explain the effect of different elements on the hydrogenation properties of the Mg-based binary systems and the formation of ternary hydrides. © 2016 The Royal Society of Chemistry.","However it is too stable and does not desorb hydrogen at ambient conditions. In this study, 21 different elements were added to magnesium in atomic scale by using the High-Pressure Torsion (HPT) technique and different kinds of nanostructured intermetallics and new metastable or amorphous phases were synthesized after HPT (Mg17Al12, MgZn, MgAg, Mg2In, Mg2Sn, etc.)",_
!368,"Magnesium can serve as a solid-state hydrogen-storage material, and over recent years it has been taken into consideration owing to its high storage capacity. The effect of 10wt% nickel and graphite (G) on hydrogen sorption of magnesium was compared. The powder mixture was mechanically milled for 35h under an argon atmosphere. A Sievert apparatus was used for hydrogen sorption analysis. Scanning electron microscopy and X-ray diffraction were used for morphological characterization. Hydrogen sorption analysis was performed at 3.5MPa and 473K. The results showed that graphite had a better effect than nickel on the hydrogen storage properties of magnesium owing to a greater reduction in the particle size of magnesium and the physisorption of hydrogen by graphite. The hydrogen adsorption of Mg+10wt%G was also investigated at 2.0, 3.5, and 4.0MPa, and it was found that the compound adsorbed 5.7wt% hydrogen at 4.0MPa because hydrogen could penetrate into the inner parts of the magnesium powder at higher pressure. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.","Magnesium can serve as a solid-state hydrogen-storage material, and over recent years it has been taken into consideration owing to its high storage capacity. Scanning electron microscopy and X-ray diffraction were used for morphological characterization.",_
!369,"This review highlights a new emerging route towards improving the properties of solid-state hydrogen storage materials, the nanoconfinement of metallic particles into scaffolds. The nanostructure design enables tailoring the hydrogen sorption properties, both kinetics and thermodynamics. Among several nanostructure design approaches, the nanoconfinement of metal particles into scaffolds has the advantage of preventing coalescence and easy handling of nanoparticles. Hydrogen sorption properties of hybrids containing metallic nanoparticles and nanoalloys embedded into different scaffolds will be discussed here. Two classes of metallic nanoparticles will be addressed: noble metal-based nanoparticles and Mg-based nanospecies. © 2012 Elsevier B.V.","This review highlights a new emerging route towards improving the properties of solid-state hydrogen storage materials, the nanoconfinement of metallic particles into scaffolds. Hydrogen sorption properties of hybrids containing metallic nanoparticles and nanoalloys embedded into different scaffolds will be discussed here.",_
!370,"Mg and Zr are immiscible in the solid and liquid states and do not form any binary phases. In this study, Mg and Zr were significantly dissolved in each other by severe plastic deformation (SPD) through the high-pressure torsion (HPT) method and several new metastable phases were formed: Nanostructured hcp, nano-twinned fcc, bcc or ordered bcc-based phases. These supersaturated Mg-Zr phases, which did not decompose up to 773 K, exhibited reversible hydrogen storage capability at room temperature. They absorbed ∼1 wt.% of hydrogen under 9 MPa in ∼20 s and fully desorbed the hydrogen in the air. First-principles phonon calculations revealed that the disordered hcp and fcc solid solutions were dynamically stable in the whole composition range of the Mg-Zr system. The bcc or bcc-based ordered phases, which were formed only as intermediate phases during the phase transformation to the hcp solid solution alloy, were energetically higher and were dynamically stable only under limited conditions in the Mg-rich compositions. © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.","In this study, Mg and Zr were significantly dissolved in each other by severe plastic deformation (SPD) through the high-pressure torsion (HPT) method and several new metastable phases were formed: Nanostructured hcp, nano-twinned fcc, bcc or ordered bcc-based phases. These supersaturated Mg-Zr phases, which did not decompose up to 773 K, exhibited reversible hydrogen storage capability at room temperature.",_
!371,"A series of halide-free ammine manganese borohydrides, Mn(BH4)2·nNH3, n=1, 2, 3, and 6, a new bimetallic compound Li2Mn(BH4)4·6NH3, and the first ammine metal borohydride solid solution Mg1-xMnx(BH4)2·6NH3 are presented. Four new crystal structures have been determined by synchrotron radiation powder X-ray diffraction and the thermal decomposition is systematically investigated for all the new compounds. The solid-gas reaction between Mn(BH4)2 and NH3 provides Mn(BH4)2·6NH3. The number of NH3 per Mn has been varied by mechanochemical treatment of Mn(BH4)2·6NH3-Mn(BH4)2 mixtures giving rise to increased hydrogen purity for n/m≤1 for M(BH4)m·nNH3. The structures of Mg(BH4)2·3NH3 and Li2Mg(BH4)4·6NH3 have been revisited and new structural models are presented. Finally, we demonstrate that ammonia destabilizes metal borohydrides with low electronegativity of the metal (χp<∼1.6), while metal borohydrides with high electronegativity (χp>∼1.6) are generally stabilized. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.","A series of halide-free ammine manganese borohydrides, Mn(BH4)2·nNH3, n=1, 2, 3, and 6, a new bimetallic compound Li2Mn(BH4)4·6NH3, and the first ammine metal borohydride solid solution Mg1-xMnx(BH4)2·6NH3 are presented. Four new crystal structures have been determined by synchrotron radiation powder X-ray diffraction and the thermal decomposition is systematically investigated for all the new compounds.",_
!372,"EDEN aims at research, development and validation of a solid-state hydrogen storage technology for specific sector of stationary applications and at support of distributed grid level applications. EDEN realizes a full-scale prototype composed by a storage tank, R-SOC (reversible-Solid Oxide Cell) and an energy recovery solution, which allows overall efficiency improvement and that, is compatible for the use with ""polluted"" hydrogen. The main objectives of this research project address the development of a new storage material with high hydrogen storage capacity, loaded into a specifically designed storage tank and fully integrated with R-SOC. 10 kg material has been prepared. The intermediate tests demonstrated 7.1 w/w % hydrogen density on the material. Once completed the development and lab characterization, EDEN system prototype has been installed in FBK in Trento, in order to evaluate system performances in real working condition. The demonstration of the technology will be completed in Barcelona, in a selected site controlled by the Barcelona Energy Agency.","EDEN realizes a full-scale prototype composed by a storage tank, R-SOC (reversible-Solid Oxide Cell) and an energy recovery solution, which allows overall efficiency improvement and that, is compatible for the use with ""polluted"" hydrogen. The main objectives of this research project address the development of a new storage material with high hydrogen storage capacity, loaded into a specifically designed storage tank and fully integrated with R-SOC.",_
!373,"For practical solid-state hydrogen storage, reversibility under mild conditions is crucial. Complex metal hydrides such as NaAlH4 and LiBH4 have attractive hydrogen contents. However, hydrogen release and especially uptake after desorption are sluggish and require high temperatures and pressures. Kinetics can be greatly enhanced by nanostructuring, for instance by confining metal hydrides in a porous carbon scaffold. We present for a detailed study of the impact of the nature of the carbon-metal hydride interface on the hydrogen storage properties. Nanostructures were prepared by melt infiltration of either NaAlH4 or LiBH4 into a carbon scaffold, of which the surface had been modified, varying from H-terminated to oxidized (up to 4.4 O/nm2). It has been suggested that the chemical and electronic properties of the carbon/metal hydride interface can have a large influence on hydrogen storage properties. However, no significant impact on the first H2 release temperatures was found. In contrast, the surface properties of the carbon played a major role in determining the reversible hydrogen storage capacity. Only a part of the oxygen-containing groups reacted with hydrides during melt infiltration, but further reaction during cycling led to significant losses, with reversible hydrogen storage capacity loss up to 40% for surface oxidized carbon. However, if the carbon surface had been hydrogen terminated, ∼6 wt% with respect to the NaAlH4 weight was released in the second cycle, corresponding to 95% reversibility. This clearly shows that control over the nature and amount of surface groups offers a strategy to achieve fully reversible hydrogen storage in complex metal hydride-carbon nanocomposites. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","Only a part of the oxygen-containing groups reacted with hydrides during melt infiltration, but further reaction during cycling led to significant losses, with reversible hydrogen storage capacity loss up to 40% for surface oxidized carbon. This clearly shows that control over the nature and amount of surface groups offers a strategy to achieve fully reversible hydrogen storage in complex metal hydride-carbon nanocomposites.",_
!374,"Palladium and its alloys are model systems for studying the solid-state storage of hydrogen. Mechanical milling is commonly used to process complex powder systems for solid-state hydrogen storage; however, milling can also be used to evolve nanostructured powder to modify hydrogen sorption characteristics. In the present study, cryomilling (mechanical attrition milling in a cryogenic liquid) is used to produce nanostructured palladium-rhodium alloy powder. Characterization of the cryomilled Pd-10Rh using electron microscopy, X-ray diffraction and surface area analysis reveal that (i) particle morphology evolves from spherical to flattened disk-like particles; while (ii) crystallite size decreases from several microns to less than 100 nm; and (iii) dislocation density increases with increased cryomilling time. Hydrogen absorption and desorption isotherms as well as the time scales for absorption were measured for cryomilled Pd-10Rh, and correlated with observed microstructural changes induced by the cryomilling process. In short, as the microstructure of the Pd-10Rh alloy is refined by cryomilling: (i) the maximum hydrogen concentration in the α-phase increases, (ii) the pressure plateau becomes flatter and (iii) the equilibrium hydrogen capacity increases at pressure of 101.3 kPa. Additionally, the rate of hydrogen absorption was reduced by an order of magnitude compared to non-cryomilled (atomized) powder. © 2014, Elsevier Ltd. All rights reserved.","Palladium and its alloys are model systems for studying the solid-state storage of hydrogen. Characterization of the cryomilled Pd-10Rh using electron microscopy, X-ray diffraction and surface area analysis reveal that (i) particle morphology evolves from spherical to flattened disk-like particles; while (ii) crystallite size decreases from several microns to less than 100 nm; and (iii) dislocation density increases with increased cryomilling time.",_
!375,"Inorganic polymers, also called geopolymers, are becoming increasingly used as ecologically-friendly substitutes for Portland cement, in waste remediation applications and as fireproof building materials. However, interesting aspects of their chemistry open up a range of less well-known possibilities such as: electronic composites with carbon nanotubes, photoactive composites with oxide nanoparticles, bioactive materials, drug delivery agents, dye carrying media, novel chromatography media, precursors for oxide or non-oxide ceramics, fluorescent materials, novel catalysts, solid-state hydrogen storage media, nanoporous materials and fibre-reinforced composites. This chapter illustrates the range of possibilities for these interesting materials by discussing these more novel applications. © 2015 Elsevier Ltd All rights reserved.","Inorganic polymers, also called geopolymers, are becoming increasingly used as ecologically-friendly substitutes for Portland cement, in waste remediation applications and as fireproof building materials. However, interesting aspects of their chemistry open up a range of less well-known possibilities such as: electronic composites with carbon nanotubes, photoactive composites with oxide nanoparticles, bioactive materials, drug delivery agents, dye carrying media, novel chromatography media, precursors for oxide or non-oxide ceramics, fluorescent materials, novel catalysts, solid-state hydrogen storage media, nanoporous materials and fibre-reinforced composites.",_
!376,"Rare earth metal borohydrides have been proposed as materials for solid-state hydrogen storage because of their reasonably low temperature of decomposition. New synthesis methods, which provide halide-free yttrium and gadolinium borohydride, are presented using dimethyl sulfide and new solvates as intermediates. The solvates M(BH4)3S(CH3) 2 (M = Y or Gd) are transformed to α-Y(BH4) 3 or Gd(BH4)3 at ∼140 °C as verified by thermal analysis. The monoclinic structure of Y(BH4) 3S(CH3)2, space group P21/c, a = 5.52621(8), b = 22.3255(3), c = 8.0626(1) Å and β = 100.408(1)°, is solved from synchrotron radiation powder X-ray diffraction data and consists of buckled layers of slightly distorted octahedrons of yttrium atoms coordinated to five borohydride groups and one dimethyl sulfide group. Significant hydrogen loss is observed from Y(BH4)3 below 300 °C and rehydrogenation at 300 °C and p(H2) = 1550 bar does not result in the reformation of Y(BH4)3, but instead yields YH 3. Moreover, composites systems Y(BH4)3- LiBH4 1:1 and Y(BH4)3-LiCl 1:1 prepared from as-synthesised Y(BH4)3 are shown to melt at 190 and 220 °C, respectively. © 2014 The Royal Society of Chemistry.","Rare earth metal borohydrides have been proposed as materials for solid-state hydrogen storage because of their reasonably low temperature of decomposition. Significant hydrogen loss is observed from Y(BH4)3 below 300 °C and rehydrogenation at 300 °C and p(H2) = 1550 bar does not result in the reformation of Y(BH4)3, but instead yields YH 3.",_
!377,"Applications of hydriding materials for solid state hydrogen storage, hydrogen compression, thermal energy storage and sorption heating and cooling systems have been demonstrated successfully. However, the performance of these devices significantly depends upon heat and mass transfer characteristics of the reactive packed beds. One of the important parameters regulating heat and mass transfer in the hydriding bed is its effective thermal conductivity (ETC), which is dependent on several operating parameters such as pressure and temperature. ETC also varies significantly due to the variation of hydrogen concentration during the hydriding and dehydriding processes. Based on the extensive studies done by the authors on ETC of metal hydride beds, a review of experimental methods, mathematical studies and augmentation techniques is presented in this paper, with emphasis on the effects of operating parameters on ETC. © 2016 Elsevier Ltd. All rights reserved.","Applications of hydriding materials for solid state hydrogen storage, hydrogen compression, thermal energy storage and sorption heating and cooling systems have been demonstrated successfully. One of the important parameters regulating heat and mass transfer in the hydriding bed is its effective thermal conductivity (ETC), which is dependent on several operating parameters such as pressure and temperature.",_
!378,"The effect of chemical composition and particle size on the first hydrogenation of BCC alloy 52Ti-12V-36Cr were investigated. The alloy was studied in the undoped state and doped with 4%Zr. Three particle size ranges were selected: less than 0.5 mm, between 0.5 mm and 1 mm, and bigger than 1 mm. It was found that doping reduced the incubation time by more than two orders of magnitudes. Smaller particle size also reduces incubation time but only by a factor of three. The intrinsic hydrogenation kinetics were also significantly enhanced by doping. Moreover, there is some synergetic effect between doping and reduction of particle size. It was also found that incubation time depends on the average particle size and not on the distribution of particle sizes. © 2017 Hydrogen Energy Publications LLC",It was found that doping reduced the incubation time by more than two orders of magnitudes. Smaller particle size also reduces incubation time but only by a factor of three.,_
!379,"The exploration of favourable hydrogen storage materials is of great importance for the realization of a sustainable hydrogen energy society. Here, we report a hydrogen-induced glass-to-glass transition in Mg-based metallic glasses (MGs) with a storage capacity as high as 5 wt%-H. The hydrogen storage capacity of metallic glassy hydrides (MGHs) is obviously higher than that of their crystalline counterparts owing to the free volume and disordered atomic structure associated with glasses. The glass-to-glass transition is demonstrated by direct experimental observation using aberration-corrected scanning transmission electron microscopy combined with ab initio molecular dynamics simulations. Remarkably, the dehydrogenation temperature of the MGHs can be efficiently tuned as it shows a close relationship with the enthalpy of mixing between the alloying element and hydrogen, and can be decreased from ∼350 °C to ∼150 °C when alloying with 5 at.%-Cu. MGs therefore have great potential as solid-state hydrogen storage materials. © 2016 Acta Materialia Inc.",The hydrogen storage capacity of metallic glassy hydrides (MGHs) is obviously higher than that of their crystalline counterparts owing to the free volume and disordered atomic structure associated with glasses. The glass-to-glass transition is demonstrated by direct experimental observation using aberration-corrected scanning transmission electron microscopy combined with ab initio molecular dynamics simulations.,_
!380,"The crystal structure of an aluminum-based borohydride ammoniate - Al(BH4)3·6NH3 - is reported for the first time. The molecular structure of Al(BH4)3· 6NH3 is resolved by high-resolution X-ray diffraction. The compound crystallized in the space group Pbcn (No. 60), with lattice parameters of a = 13.2824(5) Å, b = 15.2698(7) Å and c = 13.1848(6) Å. Structure analysis shows that this compound contains complex hexamminealuminum (III) [Al(NH3)6]3+ cations, which are surrounded by BH4- anions. The interatomic distances between the Hδ+s from the NH3 units and the Hδ-s from the BH4 units are in the range of 1.91-2.19 Å, suggesting the presence of significant Hδ+â|̄-δH interactions. Mass spectrometry, thermogravimetry and temperature-programmed desorption studies of metal cation-modified aluminum-based borohydride ammoniates using the reactions of various metal borohydrides M(BH4)n (M = Na, Li, Ca, Mg) and chlorides MCln (M = Sc, Ni, Cu, Zn, Mg, Ca, Li) reveal that their dehydrogenation properties are strongly dependent on the polarizing power of the added metal cations. It is hypothesized that the added metal cations may activate the borohydride ion to such an extent that its H δ- can easily react with the Hδ+ of the [Al(NH3)6]3+ cation, resulting in an enhanced interaction between the Hδ+ and Hδ-, thus enhancing their dehydrogenation kinetics. Subsequent deuterium isotope and X-ray measurements support the hypothesis that the Hδ+â|̄ -δH interactions play a role in the dehydrogenation of the metal borohydride ammoniates. Of the systems investigated, 0.5Mg(BH 4)2/Li2Al(BH4)5· 6NH3 is notable as it releases more than 10 wt.% high-purity H 2 within 30 min below 120 C. This ranks among the highest values currently reported for potential solid-state hydrogen storage materials. These findings provide a feasible and simple route for modifying B-N-based, lightweight materials for highly efficient dehydrogenation. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.","Structure analysis shows that this compound contains complex hexamminealuminum (III) [Al(NH3)6]3+ cations, which are surrounded by BH4- anions. Mass spectrometry, thermogravimetry and temperature-programmed desorption studies of metal cation-modified aluminum-based borohydride ammoniates using the reactions of various metal borohydrides M(BH4)n (M = Na, Li, Ca, Mg) and chlorides MCln (M = Sc, Ni, Cu, Zn, Mg, Ca, Li) reveal that their dehydrogenation properties are strongly dependent on the polarizing power of the added metal cations.",_
!381,"The reaction of hydrogen with metals to form metal hydrides has numerous potential energy storage and management applications. The metal hydrogen system has a high volumetric energy density and is often reversible with a high cycle life. However, improving the often poor gravimetric performance of such systems through the use of lightweight metals usually comes at the cost of reduced reaction rates or the requirement of pressure and temperature conditions far from the desired operating conditions. Most studies of reaction kinetics of such systems focus on fitting low-dimensional kinetic models to measured rates and inferring the rate-limiting process based on the quality of the fit. This work develops a methodology for describing these reactions using a multi-process model of the physical transport and energy state transitions of interstitial hydrogen atoms within a metal lattice. In its nondimensional form, this model is applicable to arbitrary geometries and dimensions using four nondimensional kinetic parameters based on the physical transport mechanisms present in the system. The proposed model is then used for LaNi5 and TiCrMn to examine how the nucleation pattern, kinetic parameters, and particle aspect ratio affect the time of formation of a closed hydride layer and the apparent measured kinetics. The analysis is applied to both hydriding and dehydriding processes to show how different kinetic limitation mechanisms can manifest when considering the reciprocal reaction. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.","The reaction of hydrogen with metals to form metal hydrides has numerous potential energy storage and management applications. In its nondimensional form, this model is applicable to arbitrary geometries and dimensions using four nondimensional kinetic parameters based on the physical transport mechanisms present in the system.",_
!382,"In the framework of the European Cooperation in Science and Technology (COST) Action MP1103 Nanostructured Materials for Solid-State Hydrogen Storage were synthesized, characterized and modeled. This Action dealt with the state of the art of energy storage and set up a competitive and coordinated network capable to define new and unexplored ways for Solid State Hydrogen Storage by innovative and interdisciplinary research within the European Research Area. An important number of new compounds have been synthesized: metal hydrides, complex hydrides, metal halide ammines and amidoboranes. Tuning the structure from bulk to thin film, nanoparticles and nanoconfined composites improved the hydrogen sorption properties and opened the perspective to new technological applications. Direct imaging of the hydrogenation reactions and in situ measurements under operando conditions have been carried out in these studies. Computational screening methods allowed the prediction of suitable compounds for hydrogen storage and the modeling of the hydrogen sorption reactions on mono-, bi-, and three-dimensional systems. This manuscript presents a review of the main achievements of this Action. © 2016 Hydrogen Energy Publications LLC","In the framework of the European Cooperation in Science and Technology (COST) Action MP1103 Nanostructured Materials for Solid-State Hydrogen Storage were synthesized, characterized and modeled. Direct imaging of the hydrogenation reactions and in situ measurements under operando conditions have been carried out in these studies.",_
!383,"Abstract The reaction of lithium amide and imide with lithium halides to form new amide halide or imide halide phases has led to improved hydrogen desorption and absorption properties and, for the amides, lithium ion conductivities. Here we investigate the effect of bromide incorporation on the ionic conductivity and hydrogen absorption properties of lithium nitride. For the first time we show that it is possible for a lithium halide nitride, the cubic bromide nitride Li6NBr3, to take up hydrogen - a necessary condition for potential use as a reversible solid-state hydrogen storage material. Powder X-ray diffraction showed the formation of Li2Br(NH2) and LiBr, and Raman spectroscopy confirmed that only amide anions were present and that the hydrogen uptake reaction had gone to completion. The lithium ion conductivity of Li6NBr3 at the hydrogenation temperature was found to be less than that of Li3N, which may be a significant factor in the kinetics of the hydrogenation process. © 2015 Published by Elsevier B.V.","Abstract The reaction of lithium amide and imide with lithium halides to form new amide halide or imide halide phases has led to improved hydrogen desorption and absorption properties and, for the amides, lithium ion conductivities. For the first time we show that it is possible for a lithium halide nitride, the cubic bromide nitride Li6NBr3, to take up hydrogen - a necessary condition for potential use as a reversible solid-state hydrogen storage material.",_
!384,"The microstructural analysis of the dehydrogenation products of the Ca(BH4)2-MgH2 composite was performed using transmission electron microscopy. It was found that nanocrystalline CaB6 crystallites formed as a dehydrogenation product throughout the areas where the signals of Ca and Mg were simultaneously detected, in addition to relatively coarse Mg crystallites. The uniform distribution of the nanocrystalline CaB6 crystallites appears to play a key role in the rehydrogenation of the dehydrogenation products, which implies that microstructure is a crucial factor determining the reversibility of reactive hydride composites. © 2013 Microscopy Society of America.","It was found that nanocrystalline CaB6 crystallites formed as a dehydrogenation product throughout the areas where the signals of Ca and Mg were simultaneously detected, in addition to relatively coarse Mg crystallites. The uniform distribution of the nanocrystalline CaB6 crystallites appears to play a key role in the rehydrogenation of the dehydrogenation products, which implies that microstructure is a crucial factor determining the reversibility of reactive hydride composites.",_
!385,"2LiBH4-MgH2 composite is doped with 1, 5, 10, 20, and 30 wt. % activated carbon nanofibers (ACNFs), prepared by heat and KOH treatment of polyacrylonitrile (PAN)-based nanofibers for reversible hydrogen storages. Alteration of unit cell parameters and reduction of particle size of hydride materials are obtained after doping with 1-10 wt. % ACNFs, in accordance with good dispersion of ACNFs in hydride matrices, while those of the sample with higher ACNFs contents (20-30 wt. %) are comparable with milled 2LiBH4-MgH2 without ACNFs. Reduction of dehydrogenation temperature and faster kinetics are obtained with increase of ACNFs content. For example, dehydrogenation temperatures of MgH2 and LiBH4 decrease significantly from 375 to 312 °C and from 440 to 384 °C, respectively, after doping with 30 wt. % ACNFs. Besides, under the same temperature and pressure conditions (T = 400 °C under vacuum), the sample without ACNFs liberates 54% of theoretical H2 storage capacity within 9 h, while the samples with ACNFs release up to 74%. Since no chemical interaction between ACNFs and hydride materials is detected, the improvement of dehydrogenation kinetics of 2LiBH4-MgH2 composite doped with ACNFs can be due to (i) increase of hydrogen diffusion pathway from the dispersion of ACNFs in hydride matrices and (ii) good thermal conductivity of ACNFs, beneficial to heat transport during de/rehydrogenation. © 2015 Hydrogen Energy Publications, LLC.","For example, dehydrogenation temperatures of MgH2 and LiBH4 decrease significantly from 375 to 312 °C and from 440 to 384 °C, respectively, after doping with 30 wt. Besides, under the same temperature and pressure conditions (T = 400 °C under vacuum), the sample without ACNFs liberates 54% of theoretical H2 storage capacity within 9 h, while the samples with ACNFs release up to 74%.",_
!386,"Hydrogen storage is one of the key obstacles to the commercialization as well as market acceptance of hydrogen fueled vehicle. Besides the efficiency of power system, it is an extremely challenging technology to store sufficient hydrogen on the vehicle without compromising consumer requirement such as safety, space, driving range, and fuel cost. There are three main hydrogen storage methods including compression, liquefaction and hydrogen storage materials. Among the technologies currently under development, the hydrogen storage as a highly pressurized gas is the most prominent candidate for the hydrogen powered vehicle now. The advanced automobile industries have already demonstrated the highly pressurized hydrogen system on fuel cell vehicles for past several years. The hydrogen storage materials in solid state have some advantages such as high volumetric storage capacity, little energy loss, longer storage time and highest safety. Various carbonaceous and non-carbonaceous hydrogen storage materials have been studied over the past few decades. In addition, we just started to develope an hydrogen storage system for FCV based on a NaAlH4.","Various carbonaceous and non-carbonaceous hydrogen storage materials have been studied over the past few decades. In addition, we just started to develope an hydrogen storage system for FCV based on a NaAlH4.",_
!387,"Storage of renewable energy remains a significant challenge for the implementation of a future carbon neutral and sustainable society based on renewable energy. New technologies providing a paradigm shift for energy storage may likely be based on novel materials with new functionalities. This review provides new perspectives for rational design of functional materials for energy storage using dynamic, disorder or entropy effects as a design concept. These effects may be introduced into the solid state using complex anions such as BH4- or B12H122-. These dynamic effects may facilitate anion substitution and preparation of materials that may stabilize high temperature polymorphs at lower temperatures. This has provided new ion conductors for lithium batteries and perovskite type metal borohydrides, which can be modified to resemble the well-known useful metal halide photovoltaics. Completely new metal hydrides, which stores hydrogen and may also be ion conductors or have magnetic, optical or electronic properties may be designed and prepared. This review reveals extreme structural and compositional flexibility of metal hydrides and provides new inspiration for rational materials design towards multi-functionality. © 2016 SPIE.","These effects may be introduced into the solid state using complex anions such as BH4- or B12H122-. Completely new metal hydrides, which stores hydrogen and may also be ion conductors or have magnetic, optical or electronic properties may be designed and prepared.",_
!388,An amorphous Fe(II) hydride material approximating FeH2 in composition (FeH2-xRx(Et2O)y where R = mesityl) has been isolated as a bulk powder in the solid state. This was accomplished under moderate reaction conditions by the reaction of bis(mesityl) iron(II) in toluene and hydrogen gas at 100 bar and 298 K to give a 1:5 mixed phase amorphous material of Fe(0) and the iron (II) hydride. This represents an important advance because FeH2 has never been synthesised in bulk form. The material shows ferromagnetic behaviour with a magnetic susceptibility of 1.25 Bohr magnetons per formula unit at 10 K. © 2013 Elsevier B.V. All rights reserved.,This represents an important advance because FeH2 has never been synthesised in bulk form. The material shows ferromagnetic behaviour with a magnetic susceptibility of 1.25 Bohr magnetons per formula unit at 10 K. © 2013 Elsevier B.V. All rights reserved.,_
!389,"The interest in Mg-based hydrides for solid state hydrogen storage is associated to their capability to reversibly absorb and desorb large amounts of hydrogen. In this work MgH2 powder with 5 wt.% TiO2 was ball milled for 10 h. The as-milled nanostructured powder was enriched with 5 wt.% of Expanded Natural Graphite (ENG) and then compacted in cylindrical pellets by cold pressing using different loads. Both the powder and the pellets were subjected to kinetic and thermodynamic tests using a Sievert's type gas reaction controller, in order to study the microstructural and kinetic changes which took place during repeated H2 absorption and desorption cycles. The pellets exhibited good kinetic performance and durability, even if the pressure of compaction revealed to be an important parameter for their mechanical stability. Scanning Electron Microscopy observations of as-prepared and cycled pellets were carried out to investigate the evolution of their microstructure. In turn the phase composition before and after cycling was analyzed by X-ray diffraction. © 2014 Elsevier B.V. All rights reserved.",In this work MgH2 powder with 5 wt.% TiO2 was ball milled for 10 h. The as-milled nanostructured powder was enriched with 5 wt.% of Expanded Natural Graphite (ENG) and then compacted in cylindrical pellets by cold pressing using different loads. In turn the phase composition before and after cycling was analyzed by X-ray diffraction.,_
!390,"Beside commonly known applications of activated carbon in numerous fields, it has attracted considerable amount of research attention as a medium for solid-state hydrogen storage (also known as electrochemical hydrogen storage). Hydrogen in solid-state could be stored either by physical adsorption (or physisorption) or by forming chemical bonds (or chemisorption). Activated carbon offers large internal pore surface area and high porosity that favors both physisorption and chemisorption. Other advantages of using activated carbon for electrochemical hydrogen storage are different pore sizes - macropores, mesopores, micropores and ultramicropores, low atomic weight and easy availability. The present chapter reports on experimental investigation on different grades of activated carbons, made from coal, for their electrochemical hydrogen storage capacity. The fabrication process of activated carbon-based solid electrodes is explained. The steps involved in testing of the fabricated electrodes for their electrochemical hydrogen storage capacity are given. The obtained hydrogen storage capacity of certain activated carbon electrodes is found to be above 1 wt% which is comparable with commercially available metal hydride-based hydrogen storage canisters, lithium-ion and lithium polymer batteries. The results pave a way forward towards commercializing activated carbon-based hydrogen storage electrodes for polymer electrolyte membrane fuel cell or PEMFC, and battery applications. © 2017 by Nova Science Publishers, Inc. All rights reserved.","Beside commonly known applications of activated carbon in numerous fields, it has attracted considerable amount of research attention as a medium for solid-state hydrogen storage (also known as electrochemical hydrogen storage). The results pave a way forward towards commercializing activated carbon-based hydrogen storage electrodes for polymer electrolyte membrane fuel cell or PEMFC, and battery applications.",_
!391,"The MgH2/LiAlH4 destabilised system was studied experimentally using the method of ball milling. The desorption/absorption performances and reaction mechanism of the 4MgH2 + LiAlH4 composite system with SrFe12O19 additive have been investigated for the first time. Analysis of the temperature-programme-desorption showed that the 5 wt% SrFe12O19-doped 4MgH2 + LiAlH4 composite started to release hydrogen at 80 °C and 260 °C for the first two desorption stages, which were reduced by 40 °C and 10 °C as compared to the undoped composite. The sorption kinetics of 5 wt% SrFe12O19-doped 4MgH2 + LiAlH4 were also improved as compared to the undoped 4MgH2 + LiAlH4. Activation energy calculation based on the Kissinger plot displayed that the apparent activation energy for the decomposition of MgH2-relevant had been reduced from 121 kJ/mol for the undoped composite to 104 kJ/mol for the composite with SrFe12O19. The X-ray diffraction results suggested that the new species of Al2Sr and Li2Fe3O4 that were formed in situ during the heating process were believed to play a catalytic role, thus responsible for the enhancement of the hydrogen storage properties of 4MgH2 + LiAlH4 composite system with SrFe12O19. © 2017 Hydrogen Energy Publications LLC","Analysis of the temperature-programme-desorption showed that the 5 wt% SrFe12O19-doped 4MgH2 + LiAlH4 composite started to release hydrogen at 80 °C and 260 °C for the first two desorption stages, which were reduced by 40 °C and 10 °C as compared to the undoped composite. The X-ray diffraction results suggested that the new species of Al2Sr and Li2Fe3O4 that were formed in situ during the heating process were believed to play a catalytic role, thus responsible for the enhancement of the hydrogen storage properties of 4MgH2 + LiAlH4 composite system with SrFe12O19.",_
!392,"In this paper, a numerical study of coupled heat and hydrogen transfer characteristics in an annular cylindrical hydrogen storage reactor filled with Mg2Ni is presented. An unsteady, two-dimensional (2-D) mathematical model of a metal hydride reaction bed of cylindrical configuration is developed for predicting the hydrogen storage capacity. The effect of volumetric radiation is accounted in the thermal model. Effects of hydride bed thickness, initial absorption temperature, hydride bed thermal conductivity, and hydrogen supply pressure on the hydrogen storage capacity are studied. A thinner hydride bed is found to enhance the hydriding rate, accomplishing a rapid reaction. At an operating condition of 20 bar supply pressure and 573 K initial absorption temperature, Mg2Ni stores about 36.7 g hydrogen per kg alloy. For a given bed thickness and an overall heat transfer coefficient, there exists an optimum value of hydride bed thermal conductivity. The present numerical results are compared with the experimental data reported in the literature, and good agreement was observed. Copyright © 2014 Taylor and Francis Group, LLC.","In this paper, a numerical study of coupled heat and hydrogen transfer characteristics in an annular cylindrical hydrogen storage reactor filled with Mg2Ni is presented. At an operating condition of 20 bar supply pressure and 573 K initial absorption temperature, Mg2Ni stores about 36.7 g hydrogen per kg alloy.",_
!393,"Light metal tetrahydroborates are regarded as promising materials for solid state hydrogen storage. Due to both a high gravimetric hydrogen capacity of 11.5 wt % and an ideal dehydrogenation enthalpy of 32 kJ mol-1 H 2, Ca(BH4)2 is considered to be one of the most interesting compounds in this class of materials. In this work, a comprehensive investigation of the effect of different selected additives (TiF4, NbF5, Ti-isopropoxide, and CaF2) on the reversible hydrogenation reaction of calcium borohydride is presented combining different investigation techniques. The chemical state of the Nb- and Ti-based additives is studied by X-ray absorption spectroscopy (e.g., XANES). Transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDX) was used to show the local structure, size, and distribution of the additive/catalyst. 11B{1H} solid state magic angle spinning-nuclear magnetic resonance (MAS NMR) was carried out to detect possible amorphous phases. The formation of TiB 2 and NbB2 nanoparticles was observed after milling or upon sorption reactions of the Nb- and Ti-based Ca(BH4)2 doped systems. The formation of transition-metal boride nanoparticles is proposed to support the heterogeneous nucleation of CaB6. The {111}CaB6/{1011}NbB2, {111}CaB6/{1010}NbB 2, as well as {111}CaB6/{1011}TiB2 plane pairs have the potential to be the matching planes because the d-value mismatch is well below the d-critical mismatch value (6%). Transition-metal boride nanoparticles act as heterogeneous nucleation sites for CaB6, refine the microstructure thus improving the sorption kinetics, and, as a consequence, lead to the reversible formation of Ca(BH4)2. © 2013 American Chemical Society.",Light metal tetrahydroborates are regarded as promising materials for solid state hydrogen storage. 11B{1H} solid state magic angle spinning-nuclear magnetic resonance (MAS NMR) was carried out to detect possible amorphous phases.,_
!394,"Magnesium hydride is a promising candidate for solid-state hydrogen storage and thermal energy storage applications. A series of Ti-based intermetallic alloy (TiAl, Ti3Al, TiNi, TiFe, TiNb, TiMn2, and TiVMn)-doped MgH2 materials were systematically investigated in this study to improve its hydrogen storage properties. The dehydrogenation and hydrogenation properties were studied by using both thermogravimetric analysis and pressure-composition-temperature (PCT) isothermal to characterize the temperature of dehydrogenation and the kinetics of both desorption and absorption of hydrogen by these doped MgH2. Results show significant improvements of both dehydrogenation and hydrogenation kinetics as a result of adding the Ti intermetallic alloys as catalysts. In particular, the TiMn 2-doped Mg demonstrated extraordinary hydrogen absorption capability at room temperature and 1 bar hydrogen pressure. The PCT experiments also show that the hydrogen equilibrium pressures of MgH2 were not affected by these additives. © 2013 American Chemical Society.","A series of Ti-based intermetallic alloy (TiAl, Ti3Al, TiNi, TiFe, TiNb, TiMn2, and TiVMn)-doped MgH2 materials were systematically investigated in this study to improve its hydrogen storage properties. Results show significant improvements of both dehydrogenation and hydrogenation kinetics as a result of adding the Ti intermetallic alloys as catalysts.",_
!395,"In the present work, the behavior of hydrazine borane N2H4BH3 in the presence of alkali/alkaline-earth hydrides is investigated. (i) Hydrazine borane N2H4BH3 is readily destabilized by an alkali hydride MH (M=Li, Na, K). The electronic properties of M drive the reactivity of MH1 towards N2H4BH3. KH is the most reactive (at 25 °C, ΔrH = -70.25 kJ mol-1) while K is the least electronegative and the biggest element. Hydrazinidoboranes MN2H3BH3 form. (ii) Hydrazine borane N2H4BH3 is destabilized by MHx (x = 2, 3; M=Mg, Ca, Al). In comparison to pristine N2H4BH3, better dehydrogenation properties are found: MgH2 has a catalytic effect; CaH2 strongly destabilizes N2H4BH3; and, unstable AlH3 is able to destabilize N2H4BH3 under heating. Though the synthesis of hydrazinidoboranes M(N2H3BH3)x is difficult, the mixtures MHx-N2H4BH3 leads to composites. The most efficient composite is CaH2-N2H4BH3. The aforementioned hydrazinidoboranes and composites may have potential as solid-state hydrogen storage materials. This is discussed herein. © 2015 Hydrogen Energy Publications, LLC.","(i) Hydrazine borane N2H4BH3 is readily destabilized by an alkali hydride MH (M=Li, Na, K). The aforementioned hydrazinidoboranes and composites may have potential as solid-state hydrogen storage materials.",_
!396,"Overview of advances in the technology of solid state hydrogen storage methods applying different kinds of novel materials is provided. Metallic and intermetallic hydrides, complex chemical hydride, nanostructured carbon materials, metal-doped carbon nanotubes, metal-organic frameworks (MOFs), metal-doped metal organic frameworks, covalent organic frameworks (COFs), and clathrates solid state hydrogen storage techniques are discussed. The studies on their hydrogen storage properties are in progress towards positive direction. Nevertheless, it is believed that these novel materials will offer far-reaching solutions to the onboard hydrogen storage problems in near future. The review begins with the deficiencies of current energy economy and discusses the various aspects of implementation of hydrogen energy based economy. © 2015 Renju Zacharia and Sami ullah Rather.","The studies on their hydrogen storage properties are in progress towards positive direction. Nevertheless, it is believed that these novel materials will offer far-reaching solutions to the onboard hydrogen storage problems in near future.",_
!397,"Ammonia borane is a promising hydrogen storage material due to its high gravimetric capacity (19.6%wt), but it also presents limitations such as a slow hydrogen release with a long induction time, a difficult regeneration, or the formation of foams and gaseous by-products during thermolysis. Previous studies have shown that by nanoconfinement of ammonia borane within a porous support some of these limitations can be overcome due to the reduction and stabilization of ammonia borane particle size. However, this effect was only observed with moderate ammonia borane loadings, as with higher loadings the pores of the support became obstructed. In this work, silica aerogels produced by CO2 drying, with pore volumes up to 2 cm3/g, have been used to confine ammonia borane. The influence of the amount of ammonia borane loaded on the aerogel support on the thermal and structural properties of the material has been analyzed. It has been found that more than 60 wt% of ammonia borane can be effectively stored in the pores of the aerogel support. The resulting material shows faster hydrogen release kinetics by thermolysis at 80 °C, due to a significant reduction in the mea size of ammonia borane after confinement and the participation of SiOH and SiOSi groups of silica aerogel in the decomposition mechanism. © 2016 Elsevier Inc.","However, this effect was only observed with moderate ammonia borane loadings, as with higher loadings the pores of the support became obstructed. It has been found that more than 60 wt% of ammonia borane can be effectively stored in the pores of the aerogel support.",_
!398,"In this Part B manuscript, the performance tests on LmNi 4.91Sn0.15 based two solid state hydrogen storage devices with 36 and 60 embedded cooling tubes (ECT) during desorption of hydrogen are presented. The results of a systematic investigation of these reactors during hydrogen desorption process at different operating conditions are discussed while the absorption characteristics are reported in part A of this manuscript. The desorption characteristics of the hydrogen storage devices are studied by varying the hot fluid temperature (30 C-60 C), and the heat transfer fluid flow rate (2.2 l/min-30 l/min). In the reactor with 36 ECT and 60 ECT, with oil flow rate of 3.2 l/min, at 60 C hot fluid temperature, the hydride bed attains the initial hot fluid temperature rapidly. At the desorption condition of 50 C desorption temperature, 30 l/min of water flow rate, the reactor with 60 ECT completes the desorption of hydrogen within 8 min. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 21.","In this Part B manuscript, the performance tests on LmNi 4.91Sn0.15 based two solid state hydrogen storage devices with 36 and 60 embedded cooling tubes (ECT) during desorption of hydrogen are presented. The results of a systematic investigation of these reactors during hydrogen desorption process at different operating conditions are discussed while the absorption characteristics are reported in part A of this manuscript.",_
!399,"Mg(BH4)2 contains 14.9 mass% of hydrogen and is considered as a promising hydrogen storage material. Reversible hydrogen sorption under moderate conditions represents a main challenge for Mg(BH4)2 being utilized for solid-state hydrogen storage. Here, we achieve the reversible storage of 4.0 mass% of hydrogen at 265°C in Mg(BH4)2. That is, desorption of 7.5 mass% H at 265°C under vacuum and absorption of 4.0 mass% at 265°C and 160 bar H2. 11B MAS NMR measurements indicate that the reversible hydrogen sorption involves the formation of a decisive intermediate which shows a major resonance with a chemical shift at -50.0 ppm. The phase evolution in the hydrogen cycles as well as the capacity loss in the hydrogen sorption cycles is discussed. © 2016 SPIE.","Reversible hydrogen sorption under moderate conditions represents a main challenge for Mg(BH4)2 being utilized for solid-state hydrogen storage. That is, desorption of 7.5 mass% H at 265°C under vacuum and absorption of 4.0 mass% at 265°C and 160 bar H2.",_
!400,"Graphene-like transition metal carbide [Ti3C2X2 (X = OH and/or F)]-supported RuNi bimetallic nanoparticles (NPs) were synthesized from the co-reduction of ruthenium chloride and nickel chloride with Ti3C2X2 as a stabilizer and carrier. Ti3C2X2-supported RuNi NPs were well dispersed in aqueous solution. The as-synthesized composites were applied as catalysts in the hydrolysis of ammonia borane (AB), which is a promising solid-state hydrogen storage material for portable fuel cell application. Results indicated that the RuNi/Ti3C2X2 catalyst was highly active for the hydrolysis of AB at room temperature, with the highest turnover frequency number of 824.7 mol H2·(mol Ru·min)-1. The activation energy for the hydrolysis of AB in the aqueous phase reached 25.7 kJ/mol, which was lower than most of the reported values. Copyright © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","Graphene-like transition metal carbide [Ti3C2X2 (X = OH and/or F)]-supported RuNi bimetallic nanoparticles (NPs) were synthesized from the co-reduction of ruthenium chloride and nickel chloride with Ti3C2X2 as a stabilizer and carrier. The as-synthesized composites were applied as catalysts in the hydrolysis of ammonia borane (AB), which is a promising solid-state hydrogen storage material for portable fuel cell application.",_
!401,"The present review of the most recent patents outlines the progress made over the last five years in the search of novel materials and processes that might allow large amounts of hydrogen to be stored on board of vehicles. Worth of note are the results of certain abinitio calculations proving that some compounds not yet synthesized might, actually, show features approaching the requirements of the US Department of Energy. Significant progress has been made concerning the absorption/desorption reversibility of Li-N-H compounds (amides/imides, LiH, Li3N), borohydrides and boranes. These materials, at the actual state of the art, appear still largely inadequate to comply with DOE targets. However, their intrinsic high mass capacity offers wide margin for further research in this area. The achievements made with alanates, magnesium-based hydrides and bcc-alloy hydrides, although of great significance from a point of view of the fundamental research, nonetheless, appear to be of limited impact from a practical point of view, at least for automotive applications. This is mainly due to the relatively low intrinsic mass capacity of these materials. © 2012 Bentham Science Publishers.","Significant progress has been made concerning the absorption/desorption reversibility of Li-N-H compounds (amides/imides, LiH, Li3N), borohydrides and boranes. However, their intrinsic high mass capacity offers wide margin for further research in this area.",_
!402,"Light element complex hydrides (e.g. NaBH4) together with metal hydrides (e.g. MgH2) are considered two primary classes of solid state hydrogen storage materials. In spite of drawbacks such as unfavorable thermodynamics and poor kinetics, enhancements may occur in reactive hydride composites by nanostructuring of reactant phases and formation of more stable product phases (e.g. MgB2) which lower overall reaction enthalpy and allow reversibility. One potential system is based on mixing NaBH4 and MgH2 and subsequent ball milling, which in a 2:1 molar ratio can store considerable amounts of hydrogen by weight (up to 7.8 wt%). A study of the 2NaBX4 + MgX2 → MgB2 + 2NaX + 4X 2 (X=D,H) reaction is assessed by means of in-situ neutron diffraction with different combinations of hydrogen and deuterium on the X position. The desorption is established to begin at temperatures as low as 250 °C, starting with decomposition of nanostructured MgX2 due to joint effects of nanostructured MgX2 and its reducing effect at NaBX4. Analyses of background profile, due to the high incoherent neutron scattering of hydrogen, as a function of temperature demonstrate direct correlation of H/D desorption reactions with relative phases amount. © 2010 Materials Research Society.","One potential system is based on mixing NaBH4 and MgH2 and subsequent ball milling, which in a 2:1 molar ratio can store considerable amounts of hydrogen by weight (up to 7.8 wt%). The desorption is established to begin at temperatures as low as 250 °C, starting with decomposition of nanostructured MgX2 due to joint effects of nanostructured MgX2 and its reducing effect at NaBX4.",_
!403,"We present a comprehensive study on the controlled phase synthesis and thermal decomposition of Cd(BH2)4, a material for solid state hydrogen storage obtained via the metathesis reaction of LiBH4 with CdCl2. By adjusting the stochiometry of the reactants and controlling the mechanical milling vial temperature, we have isolated the tetragonal (P42mn) low temperature phase and the cubic (Pn3̄m) high temperature phase of the cadmium borohydride. Cd(BH2) 4 has a low thermodynamic stability and decomposes with fast kinetic at 348 K, when heated at 1 K min-1 against a backpressure of 1 bar H2. A semi-quantitative analysis reveals that the decomposition gases are composed of 1:1 H2 + B2H6 and that only Cd remains as solid crystalline phase. © 2012 Elsevier B.V. All rights reserved.","We present a comprehensive study on the controlled phase synthesis and thermal decomposition of Cd(BH2)4, a material for solid state hydrogen storage obtained via the metathesis reaction of LiBH4 with CdCl2. Cd(BH2) 4 has a low thermodynamic stability and decomposes with fast kinetic at 348 K, when heated at 1 K min-1 against a backpressure of 1 bar H2.",_
!404,"Sodium alanate NaAlH4 is a very suitable material for solid-state hydrogen storage owing to its relatively high hydrogen capacity (7.5 wt.% H2) and moderate temperatures for reversible H2 release/uptake (100-150 °C) compatible with PEM fuel cells. These temperatures are obtained by adding a dopant. TiCl3, ScCl3 or CeCl3 are known to be efficient dopants but the details of the catalytic mechanism are not fully understood yet. In this work, the H 2 sorption of NaAlH4 doped with TiCl3, ScCl3 or CeCl3 is systematically studied. The doped samples were prepared in one step by reactive ball milling of NaH and Al with 4 mol.% dopant in an H2 atmosphere. The efficiencies of the dopants are different for desorption and absorption, indicating that different catalytic mechanisms and rate limiting steps are taking place during both steps and these are described here. TiCl3 is more efficient for desorption and CeCl3 for absorption. ScCl3 is less efficient than the first two for all reactions. A mixture of TiCl3 and CeCl3 is thus added to NaAlH4 to act at the same time on the desorption and the absorption processes. The results show enhanced overall performances for H2 sorption when using this mixture compared to NaAlH4 milled with TiCl3 or CeCl3 only. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.","In this work, the H 2 sorption of NaAlH4 doped with TiCl3, ScCl3 or CeCl3 is systematically studied. The results show enhanced overall performances for H2 sorption when using this mixture compared to NaAlH4 milled with TiCl3 or CeCl3 only.",_
!405,"In the search for suitable solid state hydrogen storage systems, NaAlH 4 (7.4 wt % H2) holds great promise due to its suitable thermodynamical properties. However, hydrogen release and uptake are hampered by high activation energies, most likely due to solid state mass transfer limitations. A recent strategy to improve the hydrogen de- and rehydrogenation properties of NaAlH4 is to reduce the particle size to the nanometer scale. We prepared high loadings of nanosized NaAlH4 confined in the pores of a carbon support by melt infiltration. XRD, nitrogen physisorption, high pressure DSC and solid-state NMR are used to evidence that the molten NaAlH4 infiltrates the carbon support, and forms a nanosized NaAlH4 phase lacking long-range order. The confined NaAlH4 shows enhanced hydrogen dehydrogenation properties and rehydrogenation under mild conditions that is attributed to the nanosize and close contact to the carbon matrix. © 2010 American Chemical Society.","However, hydrogen release and uptake are hampered by high activation energies, most likely due to solid state mass transfer limitations. XRD, nitrogen physisorption, high pressure DSC and solid-state NMR are used to evidence that the molten NaAlH4 infiltrates the carbon support, and forms a nanosized NaAlH4 phase lacking long-range order.",_
!406,"Solid-state reversible hydrogen storage systems hold great promise for onboard applications. The key criteria for a successful solid-state reversible storage material are high storage capacity, suitable thermodynamic properties, and fast hydriding and dehydriding kinetics. The LiNH2 + LiH system has been utilized as an example system to illustrate these critical issues that are common among other solid-state reversible storage materials. The progress made in thermodynamic destabilization and kinetic enhancements via various approaches are emphasized. The implications of these advancements in the development of future solid-state reversible hydrogen storage materials are discussed. © TMS 2009.",Solid-state reversible hydrogen storage systems hold great promise for onboard applications. The progress made in thermodynamic destabilization and kinetic enhancements via various approaches are emphasized.,_
!407,"Hydrogen adsorption and storage using solid-state materials is an area of much current research interest, and one of the major stumbling blocks in realizing the hydrogen economy. However, no material yet researched comes close to reaching the DOE 2015 targets of 9 wt% and 80 kgm-3 at this time. To increase the physisorption capacities of these materials, the heats of adsorption must be increased to ̃20 kJ mol-1. This can be accomplished by optimizing the material structure, creating more active species on the surface, or improving the interaction of the surface with hydrogen. The main focus of this progress report are recent advances in physisorption materials exhibiting higher heats of adsorption and better hydrogen adsorption at room temperature based on exploiting the Kubas model for hydrogen binding: (η2-H2)-metal interaction. Both computational approaches and synthetic achievements will be discussed. Materials exploiting the Kubas interaction represent a median on the continuum between metal hydrides and physisorption materials, and are becoming increasingly important as researchers learn more about their applications to hydrogen storage problems.","However, no material yet researched comes close to reaching the DOE 2015 targets of 9 wt% and 80 kgm-3 at this time. The main focus of this progress report are recent advances in physisorption materials exhibiting higher heats of adsorption and better hydrogen adsorption at room temperature based on exploiting the Kubas model for hydrogen binding: (η2-H2)-metal interaction.",_
!408,"The influence of different high energy milling times and of the addition of catalysts such as Nb2O5, TiCl3 and graphite on the hydrogen absorption/desorption (A/D) kinetics of a mixture of 2LiNH2 + 1.1MgH2 has been studied in the temperature range 220-240 °C. It is found that a prolonged milling time is effective in improving the A/D kinetics, irrespective of the presence or not of any kind of tested additive. The enthalpy of decomposition reaction results to be about 40.4 kJ/mol, as derived from van't Hoff plot using the values of the plateau pressures measured in desorption mode. This thermodynamic parameter fits well with the current literature data. © 2007 Elsevier B.V. All rights reserved.","The enthalpy of decomposition reaction results to be about 40.4 kJ/mol, as derived from van't Hoff plot using the values of the plateau pressures measured in desorption mode. This thermodynamic parameter fits well with the current literature data.",_
!409,"Free-standing magnesium-nickel (Mg-Ni) films with extensive nanoscale grain structures were fabricated using a combination of pulsed laser deposition and film delaminating processes. Hydrogen sorption and desorption properties of the films, free from the influence of substrates, were investigated. Oxidation of the material was reduced through the use of a sandwiched free-standing film structure in which the top and bottom layers consist of nanometer-thick Pd layers, which also acted as a catalyst to promote hydrogen uptake and release. Hydrogen storage characteristics were studied at three temperatures, 296, 232, and 180°C, where multiple sorption/desorption cycles were measured gravimetrically. An improvement in hydrogen storage capacity over the bulk Mg-Ni target material was found for the free-standing films. As shown from a Van't Hoff plot, the thermodynamic stability of the nanograined films is similar to that of Mg2Ni. These results suggest that free-standing films, of which better control of material compositions and microstructures can be realized than is possible for conventional ball-milled powders, represent a useful materials platform for solid-state hydrogen storage research.","Free-standing magnesium-nickel (Mg-Ni) films with extensive nanoscale grain structures were fabricated using a combination of pulsed laser deposition and film delaminating processes. These results suggest that free-standing films, of which better control of material compositions and microstructures can be realized than is possible for conventional ball-milled powders, represent a useful materials platform for solid-state hydrogen storage research.",_
!410,"MgH2 is a promising material for solid-state hydrogen storage due to its high gravimetric and volumetric storage capacity and its relatively low cost. Severe plastic deformation (SPD) processing techniques are being explored as an alternative to high-energy ball-milling (HEBM) in order to obtain more air resistant materials and reduce processing times. In this work, Mg, MgH2, and MgH2-Fe mixtures were severely mechanically processed by different techniques such as high-pressure torsion (HPT), extensive cold forging, and cold rolling. A very significant grain refinement was achieved when using MgH2 instead of Mg as raw material. The mean crystallite sizes observed ranged from 10 to 30 nm, depending on the processing conditions. Enhanced H-sorption properties were observed for the MgH 2-based nanocomposites processed by HPT when compared with MgH 2 mixtures. Additionally, cold forging and cold rolling also proved effective in nanostructuring MgH2. These results suggest a high potential for innovative application with the use of low cost mechanical processing routes to produce Mg-based nanomaterials with attractive hydrogen storage properties. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.",Severe plastic deformation (SPD) processing techniques are being explored as an alternative to high-energy ball-milling (HEBM) in order to obtain more air resistant materials and reduce processing times. A very significant grain refinement was achieved when using MgH2 instead of Mg as raw material.,_
!411,"The development of a viable hydrogen storage system is one of the key challenges that must be met prior to the establishment of a true hydrogen economy. Current hydrogen storage options, such as compressed gas and liquid hydrogen, fall short of meeting vehicle manufacturers' goals for safe and efficient energy storage. The most viable long-term alternative to these options is solid-state storage, which has been proven both safe and efficient. The Savannah River National Laboratory (SRNL), with over 50 years of hydrogen storage expertise and over 25 years of expertise in solid-state storage, is working with the Department of Energy's Hydrogen Storage Center of Excellence in Metal Hydrides to help solve this key challenge. A considerable amount of the Center's current efforts involve research to develop new high capacity hydrogen storage materials. However the overall objective of the Center is to deliver a 1 kg of hydrogen prototype vessel that meets the 2010 U.S. DOE FreedomCAR targets, which includes 6wt% hydrogen in the system. To meet this challenging target, will not only require the development of a new light weight hydrogen storage material but also, will require similar breakthroughs in vessel and system design, engineering and fabrication technology. SRNL is leading this systems engineering and analysis activity for the DOE Metal Hydride Center of Excellence. The SRNL team is comprised of distinguished scientists and engineers from national laboratories, leading universities, and major corporate research centers that have extensive experience in solid-state hydrogen storage systems as well as supporting expertise in heat transfer, systems modeling and component and systems development and manufacturing. To meet the FreedomCAR storage goals, engineering and system development tasks will need to be worked in parallel with material development. This approach will ensure that material development and engineering efforts are coordinated and focused on creating a suitable storage material and a compatible storage container. This approach considers the many required tradeoffs. For example, selection of a hydrogen storage material with a high equilibrium pressure could adversely affect the vessel's pressure design and, in turn, its weight, and perhaps the overall hydrogen charging time. Lower pressure materials would permit the use of lightweight storage containers and even possible conformable tank shapes. The Center's efforts will build on the experience and ongoing work of its lead and partners. The Center will also share its knowledge and expertise to solve emerging safety and engineering issues. The major engineering and system development tasks being carried out by the center include: • Heat transfer modeling and verification • Engineering materials property measurements i.e. kinetics, heat capacity, packing density, cycling performance etc. • Material production scale-up. • Safety issues including risk identification and mitigation. • Subsystem fabrication and testing • Prototype system fabrication and testing • System modeling and integration. • Manufacturability and cost estimates. The accompanying presentation will describe the current hydrogen storage systems engineering challenges in more detail and the approach that the SRNL-led team will follow to help solve these challenges.","The most viable long-term alternative to these options is solid-state storage, which has been proven both safe and efficient. A considerable amount of the Center's current efforts involve research to develop new high capacity hydrogen storage materials.",_
!412,"In this paper, we present an accurate sensor used to monitor the concentration of hydrogen in a LaNi 5 solid-state hydrogen storage device. The monitoring technique is based on the variations of the electrical properties of the storage material related to the hydrogen content. The sensor uses the electrical resistance of the sample which is directly linked to the hydrogen concentration. A finite element model is presented to simulate the resistivity variations during hydrogenation. © 2011 IEEE.","In this paper, we present an accurate sensor used to monitor the concentration of hydrogen in a LaNi 5 solid-state hydrogen storage device. A finite element model is presented to simulate the resistivity variations during hydrogenation.",_
!413,"Hydrogen vibrational excitation was studied for CaF2-type metal hydrides synthesized from Ti-based BCC solid solution alloys using inelastic incoherent neutron scattering (IINS). Ti1.0V1.1Mn 0.9H4.5 and Ti1.0V1.2Cr 1.1H4.8 showed UNS spectra similar to that reported for TiH2. The first three peaks were isolated but the higher excitation peaks were not clear. Analysis of the spectra using curve-fitting with Gauss functions revealed that the hydrogen vibration of Ti1.0V 1.1Mn0.9H4.5 is harmonic but that of the TÍ0.7V12CrIiH48 is deviated from harmonic, which reflects a trumpet-type potential. The relation between metal-hydrogen distance and vibrational excitation energy for the above two hydrides and Ti1.1Cr 1.4Mo0.9H4.8 was compared with a series of CaF2-type binary metal hydrides. All the hydrides of the Ti-based alloys had lower vibrational excitation energies than the binary metal hydrides for the corresponding metal-hydrogen distances. ©2011 The Japan Institute of Metals.",Hydrogen vibrational excitation was studied for CaF2-type metal hydrides synthesized from Ti-based BCC solid solution alloys using inelastic incoherent neutron scattering (IINS). The relation between metal-hydrogen distance and vibrational excitation energy for the above two hydrides and Ti1.1Cr 1.4Mo0.9H4.8 was compared with a series of CaF2-type binary metal hydrides.,_
!414,"Eutectic mixture Mg-11.3 at.% Ni was modified by elements X from the 13th (Al, Ga, In) and 14th group (Si, Ge, Sn and Pb). Phase analysis and distribution of X between primary solid solution Mg-Ni-X and Mg2Ni-X compound was carried out in stabilization annealed samples before hydrogen charging and in hydrided state. In the both states, it was found that X prefers Mg 2Ni-X to Mg-Ni-X solid solution, and that the preference is stronger in the hydrided state. The effect is more pronounced for elements X from the 13th group. Suggested explanation was based on influence of X on the formation enthalpy of hydrides. It was observed that In increases the hydrogen storage capacity of the eutectic mixture. The most likely explanation is based on a strong segregation of In to phase Mg2Ni-X, and on a weak tendency of In to form phases with Mg and Ni. © 2011 Elsevier B.V. All rights reserved.","Eutectic mixture Mg-11.3 at.% Ni was modified by elements X from the 13th (Al, Ga, In) and 14th group (Si, Ge, Sn and Pb). The most likely explanation is based on a strong segregation of In to phase Mg2Ni-X, and on a weak tendency of In to form phases with Mg and Ni.",_
!415,"Determination of the minimum total weight is the main criterion in the design of a solid state hydrogen storage device for mobile or portable applications. The design should address additional requirements such as storage capacity, charge/discharge rates, space constraints, coolant temperature and hydrogen supply pressure. The typical metal hydride based storage device studied here consists of several filters to distribute hydrogen gas, and heat exchanger tubes to cool or heat the hydride bed based on whether hydrogen is absorbed or desorbed. The total weight of the system includes hydrogen storage material, heat exchanger tubes and associated heat transfer media, porous sintered filters and the cylindrical outer container. Systematic simulation of the heat and mass transfer during hydrogen sorption has been carried out for different feasible configurations. LaNi5 is used as the representative hydriding alloy in the device as its sorption performance is limited by heat transfer in the bed. The effect of geometric parameters on total system weight and charging time are plotted at specified operating conditions. These plots are used for the design of hydrogen storage devices with minimum system weight satisfying the imposed constraints. © 2009 by ASME.","The design should address additional requirements such as storage capacity, charge/discharge rates, space constraints, coolant temperature and hydrogen supply pressure. Systematic simulation of the heat and mass transfer during hydrogen sorption has been carried out for different feasible configurations.",_
!416,"Magnesium hydride (MgH2) is considered to be one of the most promising options for a solid state hydrogen storage material. However, for practical use it is still imperative to find a convenient means of overcoming its slow kinetics and high stability. In this investigation, oxide materials based on TiO2 have been prepared from alkoxide precursors using a sol-gel route. When ball milled with MgH2, the titanium oxide based additives were found to result in significantly reduced onset temperatures of dehydrogenation and increased hydrogenation and dehydrogenation rates. Dehydrogenation onset temperatures as low as 257 °C were observed, which is over 100 °C lower than for milled MgH2 with no additives. In cycling experiments at 300 °C, between pressures of 1 × 10-2 bar H2 and 6 bar H2, reaction rates for dehydrogenation and hydrogenation were found to be up to 15 times quicker than for milled MgH2 with no additives. The Ti based oxide additives were found to change the mechanism of dehydrogenation from milled MgH2 from one of surface control followed by contracting volume, to a two-dimensional Johnson-Mehl-Avrami nucleation and growth mechanism. © 2009 Elsevier B.V. All rights reserved.","Magnesium hydride (MgH2) is considered to be one of the most promising options for a solid state hydrogen storage material. However, for practical use it is still imperative to find a convenient means of overcoming its slow kinetics and high stability.",_
!417,"Complex hydrides are very promising candidates for future light-weight solid state hydrogen storage materials. The present work illustrates detailed characterization of such novel hydride materials on different size scales by the use of synchrotron radiation and neutrons. The comprehensive analysis of such data leads to a deep understanding of the ongoing processes and mechanisms. The reaction pathways during hydrogen desorption and absorption are identified by in situ X-ray diffraction (XRD). Function and size of additive phases are estimated using X-ray absorption spectroscopy (XAS) and anomalous small-angle X-ray scattering (ASAXS). The structure of the metal hydride matrix is characterized using (ultra) small-angle neutron scattering (SANS/USANS). The hydrogen distribution in tanks filled with metal hydride material is studied with neutron computerized tomography (NCT). The results obtained by the different analysis methods are summarized in a final structural model. The complementary information obtained by these different methods is essential for the understanding of the various sorption processes in light metal hydrides and hydrogen storage tanks. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.",Complex hydrides are very promising candidates for future light-weight solid state hydrogen storage materials. The reaction pathways during hydrogen desorption and absorption are identified by in situ X-ray diffraction (XRD).,_
!418,[No abstract available],[No abstract available],_
!419,"Hydrogen is the lightest and most abundant element in the universe. The overall amount of hydrogen on Earth is around 0.74. wt%; it is mostly bound in water and carbon-based materials. The future challenges of a hydrogen-based energy economy include the production, distribution and safe storage of hydrogen. Of these, one of the most important is the safe storage of hydrogen for use by consumers in electronic devices, automotive applications or heating and burning processes. A simple technical- or chemical-based solution, which fulfills all the requirements in terms of size, weight and safety for these different applications, is not yet in sight. Therefore, a number of possible solutions for the storage of hydrogen in a solid state are currently being researched. © 2012 Woodhead Publishing Limited All rights reserved.","A simple technical- or chemical-based solution, which fulfills all the requirements in terms of size, weight and safety for these different applications, is not yet in sight. Therefore, a number of possible solutions for the storage of hydrogen in a solid state are currently being researched.",_
!420,"The paper presents a model-based investigation of a metal hydride reactor applied as a solid state hydrogen storage device. The elements of a metal hydride reactor are hydrogen supply duct, internal hydrogen distribution, hydride bed, reactor shell and the flow domain of the heat transfer fluid. Internal hydrogen distribution and hydride bed are porous media. Therefore, hydrogen flows through non-porous and porous regions during its reversible exothermic absorption and endothermic desorption, respectively. The interface between porous and non-porous regions is a discontinuity with respect to energy transport mechanisms. Hence, Danckwerts-type boundary conditions for the energy balance equation are introduced. Application of the first and second law of thermodynamics to the interface reveals that temperature jumps may occur at the hydrogen inlet but are not allowed at the hydrogen outlet. Exemplarily the loading behavior of a metal hydride storage tank based on sodium alanate is analyzed. It is demonstrated and experimentally validated that only Danckwerts-type boundary conditions predict the important cooling effect of the inlet hydrogen on the exothermic absorption process correctly. © 2011 Elsevier Ltd.",The interface between porous and non-porous regions is a discontinuity with respect to energy transport mechanisms. Exemplarily the loading behavior of a metal hydride storage tank based on sodium alanate is analyzed.,_
!421,"Hydrogen storage systems utilizing high-pressure metal hydrides (HPMHs) require a highly effective heat exchanger to remove the large amounts of heat released once the hydrogen is charged into the system. Aside from removing the heat, the heat exchanger must be able to accomplish this task in an acceptably short period of time. A near-term target for this 'fill-time' is less than 5 min. In this two-part study, a new class of heat exchangers is proposed for automobile hydrogen storage systems. The first part discussed the design methodology and a 2-D computational model that was constructed to explore the thermal and kinetic behavior of the metal hydride. This paper discusses the experimental setup and testing of a prototype heat exchanger using Ti 1.1CrMn as HPMH storage material. Tests were performed to examine the influence of pressurization profile, coolant flow rate and coolant temperature on metal hydride temperature and reaction rate. The experimental data are compared with predictions of the 2-D model to validate the model, calculate reaction progress and determine fill time. The prototype heat exchanger successfully achieved a fill time of 4 min 40 s with a combination of fast pressurization and low coolant temperature. A parameter termed non-dimensional conductance (NDC) is shown to be an effective tool in designing HPMH heat exchangers and estimating fill times achievable with a particular design. © 2010 Elsevier Ltd. All rights reserved.","In this two-part study, a new class of heat exchangers is proposed for automobile hydrogen storage systems. This paper discusses the experimental setup and testing of a prototype heat exchanger using Ti 1.1CrMn as HPMH storage material.",_
!422,[No abstract available],[No abstract available],_
!423,"Among the borohydrides proposed for solid state hydrogen storage, Ca(BH4)2 is particularly interesting because of its favourable thermodynamics and relatively cheap price. Composite systems, where other species are present in addition to the borohydride, show some advantages in hydrogen sorption properties with respect to the borohydrides alone, despite a reduction of the theoretical storage capacity. We have investigated the milling time influence on the sorption properties of the CaH2 + MgB2 system from which Ca(BH4)2 and MgH 2 can be synthesized by hydrogen absorption process. Manometric and calorimetric measurements showed better kinetics for long time milled samples. We found that the total substitution of MgB2 with AlB2 in the starting material can improve the sorption properties significantly, while the co-existence of both magnesium and aluminum borides in the starting mixture did not cause any improvement. Rietveld refinements of the X-ray powder diffraction spectra were used to confirm the hypothesized reactions. © 2010 Elsevier B.V. All rights reserved.","Among the borohydrides proposed for solid state hydrogen storage, Ca(BH4)2 is particularly interesting because of its favourable thermodynamics and relatively cheap price. Manometric and calorimetric measurements showed better kinetics for long time milled samples.",_
!424,"The results of International IPHE Project “Reversible Solid State Hydrogen Storage and Purification System for FC Power Supply” are presented. The project focused on the thermal and integration aspects of metal hydride technology of hydrogen storage and purification. The experimental part of the project included various system –scale metal hydride devices for purification and storage tests. Basing on the results of mathematical modeling, the optimized from the heat and mass transfer point of view low temperature metal hydride (AB5 type) devices for the purification system were created and tested within the fully automatic purification system with capacity of 3000 st.l/hour. The test results of the 100 kg alloy hydrogen storage device integration with PEM FC also presented. It was shown experimentally, that, taking into account overall energy balance of the integrated system, it is possible to increase the total efficiency of the PEM FC based power supply system with low temperature traditional metal hydride storage. The ways for metal hydride units thermal performance improvement and capacity increase for different cases of the technology application are also presented and discussed. © 2010 18th World Hydrogen Energy Conference 2010, WHEC 2010, Proceedings. All Rights Reserved.",The results of International IPHE Project “Reversible Solid State Hydrogen Storage and Purification System for FC Power Supply” are presented. The ways for metal hydride units thermal performance improvement and capacity increase for different cases of the technology application are also presented and discussed.,_
!425,"Metal hydrides are formed when certain metals or alloys are exposed to hydrogen at favorable temperatures and pressures. In order to sustain the sorption of hydrogen during this exothermic process, the generated heat has to be removed effectively. Release of hydrogen is an endothermic process needing supply of heat to the metal hydride matrix. Depending on the application, the heat transfer medium can be either a liquid or a gas. Reduction of the total weight of hydrogen storage devices is essential towards utilization of hydrogen for mobile and portable applications. While a variety of new storage materials with desirable sorption characteristics are being suggested, optimal thermal design of the storage device remains a major challenge. Lack of thermodynamic, transport and thermophysical property data of the material particles and of the bed is another drawback which needs to be addressed. © 2010 by ASME.","In order to sustain the sorption of hydrogen during this exothermic process, the generated heat has to be removed effectively. While a variety of new storage materials with desirable sorption characteristics are being suggested, optimal thermal design of the storage device remains a major challenge.",_
!426,"This study explores the use of a high-pressure metal hydride (HPMH), Ti1.1CrMn, to store hydrogen at high pressures (up to 310 bar) and temperatures below 60 °C, conditions that are suitable for automobile fuel cells. However, the exothermic reaction of hydrogen with this material releases large amounts of heat, and the reaction rate depends on the metal hydride temperature, decreasing significantly if the heat is not removed quickly. Therefore, a powerful heat exchanger constitutes the most crucial component of a HPMH hydrogen storage system. For automobiles, this heat exchanger must enable fueling 5 kg of hydrogen in less than 5 min. This is a formidable challenge considering the enormous amount of heat that must be released and the stringent limits on the heat exchanger's weight and volume, let alone a host of manufacturing requirements. Unlike conventional heat exchangers that are designed to exchange heat between two fluids, this heat exchanger is quite unique in that it must dissipate heat between a reacting powder and a coolant. In this first of a two-part study, a systematic heat exchanger design methodology is presented, starting with a 1-D criterion and progressing through a series of engineering decisions supported by computations of fill time. A final design is arrived at that meets the 5-min fill time requirement corresponding to minimum heat exchanger mass, supported by a 2-D computational model of the heat exchanger's thermal and kinetic response. © 2010 Elsevier Ltd. All rights reserved.","For automobiles, this heat exchanger must enable fueling 5 kg of hydrogen in less than 5 min. A final design is arrived at that meets the 5-min fill time requirement corresponding to minimum heat exchanger mass, supported by a 2-D computational model of the heat exchanger's thermal and kinetic response.",_
!427,"We demonstrate that NaAlH4 confined within the nanopores of a titanium-functionalized metal-organic framework (MOF) template MOF-74(Mg) can reversibly store hydrogen with minimal loss of capacity. Hydride-infiltrated samples were synthesized by melt infiltration, achieving loadings up to 21 wt %. MOF-74(Mg) possesses one-dimensional, 12 Å channels lined with Mg atoms having open coordination sites, which can serve as sites for Ti catalyst stabilization. MOF-74(Mg) is stable under repeated hydrogen desorption and hydride regeneration cycles, allowing it to serve as a ""nanoreactor"". Confining NaAlH4 within these pores alters the decomposition pathway by eliminating the stable intermediate Na3AlH6 phase observed during bulk decomposition and proceeding directly to NaH, Al, and H2, in agreement with theory. The onset of hydrogen desorption for both Ti-doped and undoped nano-NaAlH4@MOF-74(Mg) is ∼50 °C, nearly 100 °C lower than bulk NaAlH4. However, the presence of titanium is not necessary for this increase in desorption kinetics but enables rehydriding to be almost fully reversible. Isothermal kinetic studies indicate that the activation energy for H2 desorption is reduced from 79.5 kJ mol-1 in bulk Ti-doped NaAlH4 to 57.4 kJ mol-1 for nanoconfined NaAlH4. The structural properties of nano-NaAlH 4@MOF-74(Mg) were probed using 23Na and 27Al solid-state MAS NMR, which indicates that the hydride is not decomposed during infiltration and that Al is present as tetrahedral AlH4 ® anions prior to desorption and as Al metal after desorption. Because of the highly ordered MOF structure and monodisperse pore dimensions, our results allow key template features to be identified to ensure reversible, low-temperature hydrogen storage. © 2012 American Chemical Society.","MOF-74(Mg) is stable under repeated hydrogen desorption and hydride regeneration cycles, allowing it to serve as a ""nanoreactor"". However, the presence of titanium is not necessary for this increase in desorption kinetics but enables rehydriding to be almost fully reversible.",_
!428,"Exploring and evaluating on-board solid state hydrogen storage systems performance are of great interest for fuel cell electric vehicles development. In this report, we present gravimetric and volumetric capacities of a hydrogen storage system based on a densified MOF-177 adsorbent. This is, to our knowledge, the first thorough study of an engineered industrial scale MOFs for hydrogen storage application. The measurements were performed over the 50-120 K and 0-40 bar ranges, and modeled using micropore filling approaches. The performances of a potential 100 L vessel filled with the densified MOF-177 are inferred from the modeling parameters. A comparison of this technology with the 70 MPa compressed gas hydrogen system shows under which conditions the adsorbent offer advantages in terms of volumetric and gravimetric capacities. Further comparison with AX-21 activated carbon pellets reveals that densified MOF-177 stores about 40% more at 77 K and 35 bar. In order to get a physically sound modeling analysis, we introduced an approach to establish effective saturation pressures for supercritical adsorption. This approach insures a consistency between key model parameters and the observed liquid properties of the adsorbed phase at the lowest temperatures. We show that modeling using temperature-dependent saturation pressures and adsorbed phase densities leads to important differences in the projected usable storage capacities. Such differences can be as much as 25% at 50 K in the high pressure limit, revealing the importance of physical insights in the modeling approach. © 2011 The Royal Society of Chemistry.",Exploring and evaluating on-board solid state hydrogen storage systems performance are of great interest for fuel cell electric vehicles development. We show that modeling using temperature-dependent saturation pressures and adsorbed phase densities leads to important differences in the projected usable storage capacities.,_
!429,"Proof-of-principle gas-reservoir MnNiMg electrochromic mirror devices have been investigated. In contrast to conventional electrochromic approaches, hydrogen is stored (at low concentration) in the gas volume between glass panes of the insulated glass units (IGUs). The elimination of a solid state ion storage layer simplifies the layer stack, enhances overall transmission, and reduces cost. The cyclic switching properties were demonstrated and system durability improved with the incorporation a thin Zr barrier layer between the MnNiMg layer and the Pd catalyst. Addition of 9% silver to the palladium catalyst further improved system durability. About 100 full cycles have been demonstrated before devices slow considerably. Degradation of device performance appears to be related to Pd catalyst mobility, rather than delamination or metal layer oxidation issues originally presumed likely to present significant challenges. © 2008.","In contrast to conventional electrochromic approaches, hydrogen is stored (at low concentration) in the gas volume between glass panes of the insulated glass units (IGUs). Addition of 9% silver to the palladium catalyst further improved system durability.",_
!430,"Intermetallic compounds are able to store reversibly large amount of hydrogen. The hydride formation usually takes place through a two-phase domain for which an equilibrium plateau is observed between the metallic phase and its hydride. Such phase transformation induces important structural changes such as volume expansion (either isotropic and anisotropic), symmetry lowering, hydrogen ordering and phase transitions. In some cases, change of the electronic structure, from metallic to ionocovalent state, is reported. Finally, amorphization can occur leading to disproportionation of the parent compound. In this overview we give some examples of these different behaviors to illustrate the fascinating structural properties of these materials that are of potential interest from the fundamental point of view and for practical applications like energy storage either by solid-gas or electrochemical routes. © by Oldenbourg Wissenschaftsverlag, München.","Intermetallic compounds are able to store reversibly large amount of hydrogen. In some cases, change of the electronic structure, from metallic to ionocovalent state, is reported.",_
!431,"Metal hydrides are likely candidates for the solid state storage of hydrogen. NaAlH4 is the only complex metal hydride identified so far that combines favorable thermodynamics with a reasonable hydrogen storage capacity (5.5 wt %) when decomposing in two steps to NaH, Al, and H2. The slow kinetics and poor reversibility of the hydrogen desorption can be combatted by the addition of a Ti-based catalyst. In an alternative approach we studied the influence of a reduced NaAlH4 particle size and the presence of a carbon support. We focused on NaAlH4/porous carbon nanocomposites prepared by melt infiltration. The NaAlH4 was confined in the mainly 2-3 nm pores of the carbon, resulting in a lack of long-range order in the NaAlH4 structure. The hydrogen release profile was modified by contact with the carbon; even for ∼10 nm NaAlH4 on a nonporous carbon material the decomposition of NaAlH4 to NaH, Al, and H2 now led to hydrogen release in a single step. This was a kinetic effect, with the temperature at which the hydrogen was released depending on the NaAlH4 feature size. However, confinement in a nanoporous carbon material was essential to not only achieve low H2 release temperatures, but also rehydrogenation at mild conditions (e.g., 24 bar H 2 at 150 °C). Not only had the kinetics of hydrogen sorption improved, but the thermodynamics had also changed. When hydrogenating at conditions at which Na3AlH6 would be expected to be the stable phase (e.g., 40 bar H2 at 160 °C), instead nanoconfined NaAlH4 was formed, indicating a shift of the NaAlH 4↔Na3AlH6 thermodynamic equilibrium in these nanocomposites compared to bulk materials. © 2010 American Chemical Society.","Metal hydrides are likely candidates for the solid state storage of hydrogen. NaAlH4 is the only complex metal hydride identified so far that combines favorable thermodynamics with a reasonable hydrogen storage capacity (5.5 wt %) when decomposing in two steps to NaH, Al, and H2.",_
!432,"The present work reports the straightforward preparation of sodium amidoborane NaNH2BH3, an ammonia borane derivative (NH3BH3). NaNH2BH3 is a promising solid-state hydrogen storage material, known to dehydrogenate in milder conditions than its parent compound. The preparation was made from sodium hydride NaH and NH3BH3 according to three different energy-efficient routes: namely, ball-milling, grinding in a mortar, and simple mixing with a spatula. In each case, NaNH2BH3 was formed. In other words, it has been demonstrated that the solid-solid reaction between NaH and NH3BH3 can take place by simple contact of these molecules, owing to the basic character of the former and the acidity of the latter. The as-formed materials dehydrogenate to a high extent at low temperature, with ca. 2 equivalent hydrogen H2 (NH3-free in our conditions) evolving at temperatures up to 95 °C. An effective gravimetric hydrogen density of ca. 7.4 wt% was calculated, which may correspond to an effective capacity of 3.7 wt% (assuming the weight of NaNH 2BH3 amounts to 50% of the weight of the whole storage system). Such performance confirms the high potential of amidoboranes as hydrogen storage material, especially when compared to NH3BH 3. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.","NaNH2BH3 is a promising solid-state hydrogen storage material, known to dehydrogenate in milder conditions than its parent compound. Such performance confirms the high potential of amidoboranes as hydrogen storage material, especially when compared to NH3BH 3.",_
!433,"The following composite hydride systems: NaBH4-MgH2, MgH2-LiAlH4, MgH2-VH0.81 and MgH2-NaAlH4, were synthesized in a wide range of compositions by controlled reactive/mechanical (ball) milling in a magneto-mill. In effect, composites having nanometric grain sizes of the constituent phases (nanocomposites) were produced. It is shown that the hydrogen desorption temperature of the composite constituent with the higher desorption temperature in the systems such as NaBH4 + MgH2, MgH2 + VH0.81 and MgH2 + LiAlH4 substantially decreases linearly with increasing volume fraction of the constituent having lower desorption temperature according to the well-known composite rule-of-mixtures (ROM). It is also shown that the ROM behavior can break down due to an ineffective milling of a composite. The composite system MgH2 + NaAlH4 does not obey the ROM behavior. © 2008 Elsevier B.V. All rights reserved.","In effect, composites having nanometric grain sizes of the constituent phases (nanocomposites) were produced. It is also shown that the ROM behavior can break down due to an ineffective milling of a composite.",_
!434,"This study employed a fast, simple and cost-effective hydriding combustion synthesis (HCS) to prepare nano/submicron Mg based alloys, which are the most promising solid state hydrogen storage materials owing to their high storage capacity (7.6 wt.%) and highest volumetric density. The microstructural and absorption/desorption kinetic properties of the prepared MgH2 samples were characterized and compared with commercially available MgH2 powders. The detailed BET analysis of the HCS prepared samples showed a higher surface area than that of commercial MgH2, which resulted in better absorption/desorption kinetics. The HCS-prepared MgH2 powder absorbed 6.2 wt.% H2 with a rate of 0.31 wt.%/min, whereas it desorbed at a rate of 0.98 wt.%/min. These results highlight the superiority of the HCS method to prepare MgH2 powders over conventional ingot-metallurgy. © 2011 Elsevier B.V.","This study employed a fast, simple and cost-effective hydriding combustion synthesis (HCS) to prepare nano/submicron Mg based alloys, which are the most promising solid state hydrogen storage materials owing to their high storage capacity (7.6 wt.%) and highest volumetric density. The detailed BET analysis of the HCS prepared samples showed a higher surface area than that of commercial MgH2, which resulted in better absorption/desorption kinetics.",_
!435,"On the basis of a previously acquired experience on scaling up issues concerning the use of magnesium hydride as a base material for solid-state hydrogen storage, a small reactor was designed and tested in different operating conditions. It contains about 10 g of catalyzed magnesium hydride powder mixed with 5 wt.% aluminium powder and pressed in the form of cylindrical pellets and the heat flow is managed by means of an oil circulation system. Carbon paper is used to ensure good heat conductivity between the pellets and the inner wall of the reactor and between one pellet and another. A number of hydrogen absorption and desorption cycles at different temperatures and pressures was carried out to compare the behaviour of the small reactor with the laboratory data obtained on small amounts (fractions of grams) of powdered and pelletized samples. Data acquisition for gas flow, pressure and temperature in different positions of the reactor allow a good understanding of internal dynamics. The results in terms of hydrogen absorption/desorption kinetics and of stability to ongoing cycles are stimulating, so that the tested small reactor can be considered as a basic element for further studies and improvements. © 2010 Elsevier B.V. All rights reserved.","On the basis of a previously acquired experience on scaling up issues concerning the use of magnesium hydride as a base material for solid-state hydrogen storage, a small reactor was designed and tested in different operating conditions. The results in terms of hydrogen absorption/desorption kinetics and of stability to ongoing cycles are stimulating, so that the tested small reactor can be considered as a basic element for further studies and improvements.",_
!436,"Complex hydrides are attractive candidates for solid-state hydrogen storage because of their high hydrogen storage capacities and moderate operation temperatures. However, the fast and efficient transport of reaction heat through the hydride bed is an unsolved problem due to the low intrinsic heat conductivities of complex hydrides. Here, we report on increasing the effective thermal conductivities of a NaAlH 4- and a LiNH 2-MgH 2-based material by admixing expanded natural graphite (ENG) up to 25 mass% and compaction with up to 400 MPa. Thermal conductivities in radial and axial direction, microstructure and phase fractions of these pellets were determined. With increasing ENG content the heat transfer characteristics of both systems were enhanced from less than 1 W m -1 K -1 up to 38 W m -1 K -1. The pelletized hydride-graphite composites can be processed easily and safely compared to loose powders. Further, they have increased volumetric storage capacities of up to 59 g-H 2 l -1 and 54 g-H 2 l -1 compared to the loose powders with 19 g-H 2 l -1 and 18 g-H 2 l -1 for the NaAlH 4- and a LiNH 2-MgH 2-based material, respectively, and they are very suitable for a tubular hydride tank design due to anisotropic heat transfer characteristics. © 2012 Elsevier B.V. All rights reserved.","Here, we report on increasing the effective thermal conductivities of a NaAlH 4- and a LiNH 2-MgH 2-based material by admixing expanded natural graphite (ENG) up to 25 mass% and compaction with up to 400 MPa. The pelletized hydride-graphite composites can be processed easily and safely compared to loose powders.",_
!437,"Hydrogen is an ideal energy carrier which is considered for future transport, such as automotive applications. In this context storage of hydrogen is one of the key challenges in developing hydrogen economy. The relatively advanced storage methods such as high-pressure gas or liquid cannot fulfill future storage goals. Chemical or physically combined storage of hydrogen in other materials has potential advantages over other storage methods. Intensive research has been done on metal hydrides recently for improvement of hydrogenation properties. The present review reports recent developments of metal hydrides on properties including hydrogen-storage capacity, kinetics, cyclic behavior, toxicity, pressure and thermal response. A group of Mg-based hydrides stand as promising candidate for competitive hydrogen storage with reversible hydrogen capacity up to 7.6 wt% for on-board applications. Efforts have been devoted to these materials to decrease their desorption temperature, enhance the kinetics and cycle life. The kinetics has been improved by adding an appropriate catalyst into the system and as well as by ball-milling that introduces defects with improved surface properties. The studies reported promising results, such as improved kinetics and lower decomposition temperatures, however, the state-of-the-art materials are still far from meeting the aimed target for their transport applications. Therefore, further research work is needed to achieve the goal by improving development on hydrogenation, thermal and cyclic behavior of metal hydrides. © 2006 International Association for Hydrogen Energy.","The present review reports recent developments of metal hydrides on properties including hydrogen-storage capacity, kinetics, cyclic behavior, toxicity, pressure and thermal response. Therefore, further research work is needed to achieve the goal by improving development on hydrogenation, thermal and cyclic behavior of metal hydrides.",_
!438,"Complex hydrides exhibit various energy-related functions such as hydrogen storage, microwave absorption, and neutron shielding. Furthermore, another novel energy-related function was recently reported by the authors; lithium fast-ionic conduction, which suggests that complex hydrides may be a potential candidate for solid electrolytes in lithium-ion batteries. This review presents the recent progress in the development of lithium fast-ionic conductors of complex hydrides. First, the fast-ionic conduction in LiBH 4 as a result of clarifying the mechanism of microwave absorption is presented, and then the conceptual development of complex hydrides as a new type of solid-state lithium fast-ionic conductors in LiBH 4-, LiNH 2-, and LiAlH 4-based complex hydrides is discussed. Finally, the future prospects of this study from both application and fundamental viewpoints are described: possible use as solid electrolytes for batteries, formation of ionic liquids in complex hydrides, and similarity between complex hydrides and Laves-phase metal hydrides. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.","Complex hydrides exhibit various energy-related functions such as hydrogen storage, microwave absorption, and neutron shielding. Furthermore, another novel energy-related function was recently reported by the authors; lithium fast-ionic conduction, which suggests that complex hydrides may be a potential candidate for solid electrolytes in lithium-ion batteries.",_
!439,"A major technological barrier currently preventing the proposed transition to a ""hydrogen economy"" is the storage of hydrogen for use as an energy carrier. There are various methods available, but none of these can currently achieve the required storage densities. The use of a reversible solid state hydrogen storage material, however, is one of the most promising potential solutions to this problem. In this opening chapter, we will look at some of the background to this topic, including the use of hydrogen as an energy carrier, the barriers to the widespread use of hydrogen energy in transportation technology, the different methods that can be used for the storage of hydrogen and the use of solid state media. We will then introduce the measurement methods for hydrogen uptake determination and some of the complementary characterisation techniques that can be used. We also discuss the reasons why the accurate characterisation of the storage properties of a material is an important and high profile topic. We will close the chapter by defining some of the terminology used throughout the book. © Springer-Verlag London Limited 2011.","A major technological barrier currently preventing the proposed transition to a ""hydrogen economy"" is the storage of hydrogen for use as an energy carrier. There are various methods available, but none of these can currently achieve the required storage densities.",_
!440,"There are a few different approaches for hydrogen transportation and storage. Hydrogen can be stored as a compressed gas, as a liquid (at 20 K), and in solid state compounds. The first two methods are established technologies with several limitations, the most important being their energy intensive character. Hydrogen storage in metal hydrides is considered one of the most attractive methods. While hydrogen has many obvious advantages, there remains a problem with storage and transportation. Hydrides reduce the risk factors of gaseous or liquid hydrogen. The metal hydrides provide a safe method for fuel storage in hydrogen-powered vehicles. LiBH4 is a complex hydride which consists of 18% mass of hydrogen. Therefore, there are many reasons why hydrogen-storage materials, for example LiBH4, will be used in the future at many ranges. Hydride formation, reaction (absorption and/or chemisorption) between metal (M) and hydrogen (H2) is: M + nH2 [image omitted] MH2n+ Q.","While hydrogen has many obvious advantages, there remains a problem with storage and transportation. The metal hydrides provide a safe method for fuel storage in hydrogen-powered vehicles.",_
!441,"Complex hydrides are potential candidates for solid state hydrogen storage due to their high gravimetric hydrogen capacities. The present chapter focuses on the most recent progress in the understanding of the hydrogen storage behavior of light metal-based complex hydrides and their (nano)composites. Hydrides such as sodium (NaAlH4) and lithium (LiAlH4) alanate containing various catalyzing additives, complex hydride (nano)composite systems containing LiAlH4, lithium amide (LiNH2) and magnesium hydride (MgH2) as well as manganese borohydride (Mn(BH4)2), which was synthesized by the mechanochemical activation synthesis (MCAS) are all discussed. In particular, the phenomena of mechanical dehydrogenation and slow hydrogen discharge during a long-term storage after processing by ball milling are thoroughly discussed. Furthermore, isothermal dehydrogenation behavior of the above mentioned complex hydride systems is thoroughly discussed. © 2013 Elsevier B.V. All rights reserved.","In particular, the phenomena of mechanical dehydrogenation and slow hydrogen discharge during a long-term storage after processing by ball milling are thoroughly discussed. Furthermore, isothermal dehydrogenation behavior of the above mentioned complex hydride systems is thoroughly discussed.",_
!442,"Hydrogen has the capacity to provide society with the means to carry 'green' energy between the point of generation and the point of use. A sustainable energy society in which a hydrogen economy predominates will require renewable generation provided, for example, by artificial photosynthesis and clean, efficient energy conversion effected, for example, by hydrogen fuel cells. Vital in the hydrogen cycle is the ability to store hydrogen safely and effectively. Solid-state storage in hydrides enables this but no material yet satisfies all the demands associated with storage density and hydrogen release and uptake; particularly for mobile power. Nanochemical design methods present potential routes to overcome the thermodynamic and kinetic hurdles associated with solid state storage in hydrides. In this review we discuss strategies of nanosizing, nanoconfinement, morphological/dimensional control, and application of nanoadditives on the hydrogen storage performance of metal hydrides. We present recent examples of how such approaches can begin to address the challenges and an evaluation of prospects for further development. © CSIRO 2012.","A sustainable energy society in which a hydrogen economy predominates will require renewable generation provided, for example, by artificial photosynthesis and clean, efficient energy conversion effected, for example, by hydrogen fuel cells. Nanochemical design methods present potential routes to overcome the thermodynamic and kinetic hurdles associated with solid state storage in hydrides.",_
!443,"Hydrogen generated from clean and renewable energy sources has been considered as an alternate fuel to carbon based fossil fuels for several decades. Although many advances in hydrogen production and usage have been made, storing hydrogen remains a significant challenge. Many drawbacks including energy intensive processes, low volumetric densities, and safety concerns are associated with storing hydrogen as pressured or liquefied. Solid state hydrogen storage is considered to be the most promising method as a safe and effective storage option, but there is still no material or method that satisfies the requirements for a practical approach. A feasible hydrogen storage media should address several issues including targeted storage capacities, thermodynamics and hydrogen sorption kinetics, and safety. Nanostructured materials can provide tailor-made properties for storing and releasing hydrogen to fulfill, at least, the partial requirements. This short review, not a comprehensive review of all the materials or technologies in hydrogen storage, summarizes some of the recent developments in application of nanostructures for solid state hydrogen storage; particular attention has been devoted to the most recent development of nanocomposites with tuned dehydrogenation temperatures and kinetics through the control of pore size and surface chemistry. © (2010) Trans Tech Publications, Switzerland.","Hydrogen generated from clean and renewable energy sources has been considered as an alternate fuel to carbon based fossil fuels for several decades. Many drawbacks including energy intensive processes, low volumetric densities, and safety concerns are associated with storing hydrogen as pressured or liquefied.",_
!444,"Mixtures of sodium alanate (NaAlH 4) with the nanometric Ni (n-Ni) additive were processed by controlled ball milling for 15 min in a magneto-mill and subsequently investigated by Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD) and volumetric hydrogen desorption in a Sieverts-type apparatus. The apparent activation energy of the decomposition of Na 3AlH 6, which is the decomposition product in the first dehydrogenation step of NaAlH 4, is equal to ~140 kJ/mol and ~101 kJ/mol for ball milled NaAlH 4 and NaAlH 4 +5 wt% n-Ni, respectively, as determined by the Kissinger method in DSC tests. The apparent activation energy for the decomposition of NaH, which is the decomposition product in the second dehydrogenation step of Na 3AlH 6, is estimated as equal to ~143 kJ/mol and ~226 kJ/mol for ball milled NaAlH 4 and NaAlH 4+5 wt% n-Ni, respectively. It seems that the n-Ni additive accelerates the decomposition of Na 3AlH 6 but decelerates the decomposition of NaH. Volumetric desorption tests indicate a substantial enhancement of the rate of hydrogen desorption at 170 °C for the ball milled NaAlH 4+5 wt% n-Ni nanocomposite as a result of the catalytic action of n-Ni. No reaction of n-Ni with the NaAlH 4 matrix is observed during dehydrogenation at 170-280 °C. The n-Ni catalyst used in the present work compares very favorably with other catalytic additives reported in the literature (e.g., metal chlorides) which were used for the enhancement of dehydrogenation of NaAlH 4. Copyright © 2012 American Scientific Publishers All rights reserved.","Mixtures of sodium alanate (NaAlH 4) with the nanometric Ni (n-Ni) additive were processed by controlled ball milling for 15 min in a magneto-mill and subsequently investigated by Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD) and volumetric hydrogen desorption in a Sieverts-type apparatus. No reaction of n-Ni with the NaAlH 4 matrix is observed during dehydrogenation at 170-280 °C.",_
!445,"Reversibility is one of the key features for any hydrogen storage material. Borohydrides such as LiBH4 have been studied or proposed as candidates for hydrogen storage because of their high hydrogen contents (18.4 wt% for LiBH4). Limited success has been made in reducing the dehydrogenation temperature. However, full reversibility has not been realized. It is found that the dehydrogenation mechanism of metal borohydrides differs signicantly from the well-known metal hydrides such as LaNi5H 6 and MgH2 that release hydrogen in a single decomposition step through a solid state transformation of crystalline structure. The dehydrogenation of lithium borohydrides involves solid-liquid-gas reactions. Some of the steps in the multiple step decomposition processes of metal borohydrides are not reversible. Furthermore, the decomposition also produces stable intermediate compounds that cannot be rehydrided easily. Lastly, the volatile gases, such as BH3 and B2H6, evolved in decomposition of the transition metal borohydrides cause unrecoverable boron loss. Although our experiments show the partial reversibility of the doped LiBH4, it was not sustainable during dehydriding-rehydriding cycles because of the accumulation of hydrogen inert species and boron loss. Doping with additives reduces the stability of LiBH4, but it also makes LiBH4 less reversible. It raises reasonable doubt on the feasibility of making metal borohydrides suitable for reversible hydrogen storage. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.",It is found that the dehydrogenation mechanism of metal borohydrides differs signicantly from the well-known metal hydrides such as LaNi5H 6 and MgH2 that release hydrogen in a single decomposition step through a solid state transformation of crystalline structure. It raises reasonable doubt on the feasibility of making metal borohydrides suitable for reversible hydrogen storage.,_
!446,"Calcium borohydride is one of the most interesting compounds for solid-state hydrogen storage, in particular because of its high hydrogen capacity. In this paper, the synthesis of Ca(BH4)2 by metathesis reaction via ball milling of a mixture of LiBH4 and CaCl2 is described. The effectiveness of this synthesis technique and the possible substitution of Cl ions in the borohydride phases is analysed depending on the back-pressure used for milling. When performed by ball milling under Ar, the metathesis reaction is not successful. A large quantity of a solid solution Li(BH4)1-xClx remains in the sample and CaHCl is formed rather than Ca(BH4)2. In contrast, the use of H2 back-pressure during milling favours the borohydride phases rather than CaHCl and leads to the formation of a solid solution Ca(BH4)2-yCly where [BH4] - groups are partially substituted by Cl ions. This compound has a similar structure as β-Ca(BH4)2 but with smaller lattice parameters. It is present in the as-milled sample together with LiCl and Li(BH4)1-xClx. The decomposition of the mixture occurs at lower temperature than for pure LiBH4 but higher than for pure Ca(BH4)2. The presence of chlorides in the structure of borohydride compounds changes dramatically the thermal properties of the material prepared and should be considered each time a metathesis reaction is used for synthesis. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.","When performed by ball milling under Ar, the metathesis reaction is not successful. This compound has a similar structure as β-Ca(BH4)2 but with smaller lattice parameters.",_
!447,"Ammonia borane (AB) is one of the most attractive hydrides owing to its high hydrogen density (19.5 wt%). Stored hydrogen can be released by thermolysis or catalyzed hydrolysis, both routes having advantages and issues. The present study has envisaged for the first time the combination of thermolysis and hydrolysis, AB being first thermolyzed and then the solid by-product believed to be polyaminoborane [NH2BH2]n (PAB) being hydrolyzed. Herein we report that: (i) the combination is feasible, (ii) PAB hydrolyzes in the presence of a metal catalyst (Ru) at 40 °C, (iii) a total of 3 equiv. H2 is released from AB and PAB-H2O, (iv) high hydrogen generation rates can be obtained through hydrolysis, and (v) the by-products stemming from the PAB hydrolysis are ammonium borates. The following reactions may be proposed: AB → PAB + H2 and PAB + xH 2O → 2H2 + ammonium borates. All of these aspects as well as the advantages and issues of the combination of AB thermolysis and PAB hydrolysis are discussed. © 2010 Elsevier B.V. All rights reserved.","Ammonia borane (AB) is one of the most attractive hydrides owing to its high hydrogen density (19.5 wt%). Stored hydrogen can be released by thermolysis or catalyzed hydrolysis, both routes having advantages and issues.",_
!448,"The accuracy of gas phase sorption measurements performed on potential hydrogen storage materials has been the subject of much controversy in recent years, particularly in the case of adsorption by carbon nanostructures. As the technological interest in the solid state storage of hydrogen increases, it has become increasingly necessary to investigate the methods used to determine the sorption properties, and hence the storage capacities, of new and existing materials. In this paper, we briefly review the different techniques available and recent literature on the topic, discuss the possible sources of errors and present some comparative measurements on some AB5 hydrogen-absorbing intermetallics. Equilibrium pressure-composition isotherm data measured on two LaNi5-xAlx samples using commercial gravimetric and volumetric instrumentation were found to be in good agreement with each other. © 2007 Elsevier B.V. All rights reserved.","The accuracy of gas phase sorption measurements performed on potential hydrogen storage materials has been the subject of much controversy in recent years, particularly in the case of adsorption by carbon nanostructures. Equilibrium pressure-composition isotherm data measured on two LaNi5-xAlx samples using commercial gravimetric and volumetric instrumentation were found to be in good agreement with each other.",_
!449,"The study of ammonia borane (AB) with controllable dehydrogenations is an active research topic for solid-state hydrogen storage materials. The present work shows that tuning the reactivity of both B-H and N-H bonds in AB by alkaline earth metal chlorides not only results in a significantly decrease in the onset dehydrogenation temperature to 40°C but also suppresses undesirable volatile by-products due to the incorporation of alkaline earth metal chlorides in the AB dehydrogenation process. These results provide further insights into the promotion of hydrogen release from amidoboranes and related borohydride ammine complexes. Copyright © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.",The study of ammonia borane (AB) with controllable dehydrogenations is an active research topic for solid-state hydrogen storage materials. These results provide further insights into the promotion of hydrogen release from amidoboranes and related borohydride ammine complexes.,_
!450,"This perspective highlights the state-of-the-art solid-state hydrogen storage and describes newly emerging routes towards meeting the practical demands required of a solid-state storage system. The article focuses both on the physical and chemical aspects of hydrogen storage. Common to both classes of storage material is the concept of nanostructure design to tailor kinetics and thermodynamics; whether this be control of functionalised porosity or crystalline growth on the nanoscale. In the area of chemical storage, different processing and nanostructuring techniques that have been employed to overcome the barriers of slow kinetics will be discussed in addition to new chemical systems that have emerged. The prospects of porous inorganic solids, coordination polymers (metal organic frameworks; MOFs) and other polymeric matrices for physical storage of hydrogen will be highlighted. Additionally the role of inorganic nanostructures as evolving materials ""intermediate"" between physical and chemical storage systems will be discussed and their place within the fine thermodynamic balance for optimum hydrogen uptake and release considered. © 2012 The Royal Society of Chemistry.","This perspective highlights the state-of-the-art solid-state hydrogen storage and describes newly emerging routes towards meeting the practical demands required of a solid-state storage system. In the area of chemical storage, different processing and nanostructuring techniques that have been employed to overcome the barriers of slow kinetics will be discussed in addition to new chemical systems that have emerged.",_
!451,"A short review of the materials under investigation suitable for solid state hydrogen storage is presented, with particular reference to the experimental activity carried out at the laboratory of Hydrogen Group of Padova University. © 2008 Elsevier Ltd. All rights reserved.","A short review of the materials under investigation suitable for solid state hydrogen storage is presented, with particular reference to the experimental activity carried out at the laboratory of Hydrogen Group of Padova University. © 2008 Elsevier Ltd. All rights reserved.",_
!452,"We have explored metal halide doping in metal borohydrides in order to modify hydrogen desorption/absorption properties of such high-capacity solid-state hydrogen storage materials. The specific application here is 10 mol% addition of CaX2 (X = F, Cl) to Ca(BH4)2. The materials are analyzed using in-situ X-ray diffraction, differential scanning calorimetry, thermogravimetry, and IR spectroscopy, and the experimental results are compared against theoretical predictions from first-principles. Interestingly, in a fully hydrogenated state, CaCl2 dissolves into Ca(BH4)2 whereas CaF2 exists as a separate phase. During the course of dehydrogenation, CaH2-CaF2 solid solution, CaHCl, and a new Ca-H-Cl compound are observed. In-situ X-ray diffraction study reveals that CaX2 interacts with Ca(BH 4)2 in the early stage of decomposition, which could facilitate a direct decomposition of Ca(BH4)2 into CaH2 and CaB6 without forming intermediate phases such as CaB2Hx which seem to be thermodynamically in close competition with the formation of CaH2 and CaB6. Our first-principles calculation estimates that the decrease in the decomposition temperature due to the CaH2-CaX2 interaction would be less than 10 °C, and therefore the major contribution of CaX2 is to change the dehydrogenation pathway rather than the overall thermodynamics. © 2010 Elsevier B.V. All rights reserved.","The specific application here is 10 mol% addition of CaX2 (X = F, Cl) to Ca(BH4)2. During the course of dehydrogenation, CaH2-CaF2 solid solution, CaHCl, and a new Ca-H-Cl compound are observed.",_
!453,"In the future sustainable energy system, the recyclable and none-environmental pollution hydrogen-based energy is widely approved in all fields in the future. However, the severe clag, in the development process of industrialization and generalization of hydrogen-based energy, which is lack of the satisfied hydrogen storage material. Over the last decade, material-workers have had a series of researches on the preparation of solid-state hydrogen storage materials and relative hydrogen storage possibilities . The researches mainly includes the following types: (i) Steady large surface areas, such as carbon structures hydrogen storage material; (ii) All kinds of mental and different types of mental alloys, such as the hydrogen storage material based on the element Mg; (iii) All kinds of organic hydrogen storage materials, etc. This paper mainly presents the above mentioned two types of hydrogen storage materials and introduces the aspects of hydrogen storage property and mechanism, mechanical strength of material, porosity and affinity to hydrogen. ©2010 IEEE.","Over the last decade, material-workers have had a series of researches on the preparation of solid-state hydrogen storage materials and relative hydrogen storage possibilities . The researches mainly includes the following types: (i) Steady large surface areas, such as carbon structures hydrogen storage material; (ii) All kinds of mental and different types of mental alloys, such as the hydrogen storage material based on the element Mg; (iii) All kinds of organic hydrogen storage materials, etc.",_
!454,"In recent years, significant research and development efforts were spent on hydrogen storage technologies with the goal of realizing a breakthrough for fuel cell vehicle applications. This article scrutinizes design targets and material screening criteria for solid state hydrogen storage. Adopting an automotive engineering point of view, four important, but often neglected, issues are discussed: 1) volumetric storage capacity, 2) heat transfer for desorption, 3) recharging at low temperatures and 4) cold start of the vehicle. The article shall help to understand the requirements and support the research community when screening new materials. © 2009 International Association for Hydrogen Energy.","In recent years, significant research and development efforts were spent on hydrogen storage technologies with the goal of realizing a breakthrough for fuel cell vehicle applications. This article scrutinizes design targets and material screening criteria for solid state hydrogen storage.",_
!455,"Multinary complex hydrides comprised of borohydrides, amides and metal hydrides have been synthesized using the solid state mechano-chemical process. After the optimization of the system, it was found that LiBH4/ LiNH2/MgH2 exhibits potential reversible hydrogen storage behavior (>6 wt.%) at temperatures of 125-175 °C. To further improve the hydrogen performance of the system, various nano additives namely, nickel, cobalt, iron, copper, and manganese were investigated. It was observed that some of these additives (Co, Ni) lowered the hydrogen release temperature at least 75-100 °C in the major hydrogen decomposition step. While other additives acted as catalysts and increased the rate at which hydrogen was released. Combinatorial addition of selected materials were also investigated and found to have both a positive effect on kinetics and reduction in hydrogen desorption temperature. © 2010 Published by Elsevier Ltd on behalf of Professor T. Nejat Veziroglu.",While other additives acted as catalysts and increased the rate at which hydrogen was released. © 2010 Published by Elsevier Ltd on behalf of Professor T. Nejat Veziroglu.,_
!456,"Though complex metal hydrides are potential sources of solid state hydrogen storage, practical usage in transportation and power applications is limited by the slow hydrogen adsorption/desorption kinetics and high temperatures for desorption. Experimental observations on transition metal ion-doped sodium alanates reported significant improvement on the hydrogen kinetics at moderate temperatures. However, the actual dopant behavior is still a topic of discussion and the resulting mechanisms leading to changes in the thermodynamic behavior of doped-metal hydrides are still unknown. This work is focused on studying sodium aluminum hydride (NaAlH4) and the role of titanium ion dopants in the improved kinetics of sodium alanates. Density Functional Theory (DFT) geometry optimization calculations are conducted on unit cells and supercells of NaAlH4. Dopant ions replacing native lattice sites are modeled and the electronic density of states and electron density maps around atomic species analyzed to interpret the effect of dopant ions in the sodium alanate cell.","Though complex metal hydrides are potential sources of solid state hydrogen storage, practical usage in transportation and power applications is limited by the slow hydrogen adsorption/desorption kinetics and high temperatures for desorption. Density Functional Theory (DFT) geometry optimization calculations are conducted on unit cells and supercells of NaAlH4.",_
!457,"Several mixtures of LiBH 4 and Mg(BH 4) 2 borohydrides in different stoichiometric ratios (1:0, 2:1, 1:1, 1:2, 0:1), prepared by high energy ball milling, have been investigated with X-ray powder diffraction and thermal programmed desorption (TPD) volumetric analysis to test the dehydrogenation kinetics in correlation with the physical mixture composition. Afterwards mixed and unmixed borohydrides were dispersed on high specific surface area ball milled graphite by means of the solvent infiltration technique. BET and statistical thickness methods were used to characterize the support surface properties, and SEM micrographs gave a better understanding of the preparation techniques. It has been observed by TPD volumetric measurements that the confinement of the reactive borohydrides on the nanoporous supports leads to a lower dehydrogenation temperature compared to unsupported borohydrides. Moreover, a further decrease of the dehydrogenation temperature has been observed by increasing the specific surface area of the support and the pores volume and by using the prepared mixtures instead of pure materials. The dehydrogenation process seems to be favoured by the heterogeneous nucleation on the graphite surface of decomposition products or intermediate phases from melted liquid borohydrides. © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","Several mixtures of LiBH 4 and Mg(BH 4) 2 borohydrides in different stoichiometric ratios (1:0, 2:1, 1:1, 1:2, 0:1), prepared by high energy ball milling, have been investigated with X-ray powder diffraction and thermal programmed desorption (TPD) volumetric analysis to test the dehydrogenation kinetics in correlation with the physical mixture composition. Afterwards mixed and unmixed borohydrides were dispersed on high specific surface area ball milled graphite by means of the solvent infiltration technique.",_
!458,"The major obstacle in transition to the hydrogen economy is the problem of onboard hydrogen storage. Solid-state hydrogen storage is the safest and most efficient method for hydrogen storage. Most of the metal hydrides exhibit very large volumetric storage density but less than 5 wt % gravimetric hydrogen density. Light metals such as Al, B bind with four hydrogen atoms and form together with an alkali metal an ionic or partially covalent compound called complex hydride. LiBH4 is a complex hydride with 18.5 mass % gravimetric hydrogen density and 121 kg/m3 volumetric hydrogen storage capacity. The desorption temperature of LiBH4 is greater than 470°C, thus making it difficult to use for storage applications. In addition, the conditions for reversible reaction are unfavorable. Modification of thermodynamics of the hydrogenation and dehydrogenation reaction is possible by using additives which could destabilize LiBH4 by stabilizing the dehydrogenated state. This could decrease the heat of reaction and reduce the desorption temperature at the same time, making the conditions for reversible reaction more optimum. Several additives which could destabilize LiBH 4 have been reviewed. © 2010 by Begell House, Inc.","Light metals such as Al, B bind with four hydrogen atoms and form together with an alkali metal an ionic or partially covalent compound called complex hydride. The desorption temperature of LiBH4 is greater than 470°C, thus making it difficult to use for storage applications.",_
!459,"Transition from the metallic to the hydride phase is of fundamental importance to achieving hydrogen storage in the solid state. Multi-component metal hydrides belong to one of the promising categories of materials that can potentially offer high hydrogen storage capacity. Despite extensive research on metal hydrides over the past decades, the progress remains limited partly due to the inability of screening a nearly infinite number of possible alloy compositions. High throughput materials fabrication and characterization techniques therefore offer an advantage in studying multi-component alloys and their phase transition to metal hydrides. We fabricated an Mg-Ni-Al and Ca-B-Ti ternary alloy libraries using a continuous combinatorial material synthesis technique, and measured the optical reflectance to examine the formation of metal hydride phase when the alloy library was exposed to hydrogen. The results indicate that mapping the change in reflectance is a viable method to study the kinetics of hydride formation. Monitoring the optical properties provides evidence for the ""black state"" formed during the transition from α-phase to β-phase. In addition, we found that the fastest reflectance change occurred when the alloy has an Mg to Ni ratio of approximately 2:1, and with low concentration of Al. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.","We fabricated an Mg-Ni-Al and Ca-B-Ti ternary alloy libraries using a continuous combinatorial material synthesis technique, and measured the optical reflectance to examine the formation of metal hydride phase when the alloy library was exposed to hydrogen. In addition, we found that the fastest reflectance change occurred when the alloy has an Mg to Ni ratio of approximately 2:1, and with low concentration of Al. © 2010 Professor T. Nejat Veziroglu.",_
!460,"The thermal transformations in the lithium alanate-amide system consisting of lithium aluminum hydride (LiAlH4) and lithium amide (LiNH 2), mixed in a 1:1 M ratio, were investigated using the pressure-composition-temperature analysis, solid-state nuclear magnetic resonance, X-ray powder diffraction, and residual gas analysis. Below 250 °C, the alanate decomposes into Al, LiH and H2, through the formation of Li3AlH6, whereas the amide remains largely intact. The release of gaseous hydrogen corresponds to approximately 5 wt%. Above 250 °C, additional ∼4 wt% of hydrogen is produced through solid-state reactions among LiNH2, LiH and metallic Al, through the formation of intermetallic Li-Al binary alloy and an unidentified intermediate. The overall reaction of the thermochemical transformation of the LiAlH 4-LiNH2 mixture results in the production of Li 3AlN2, metallic Al, LiH and the release of 9 wt% of gaseous hydrogen. The reaction mechanism of the thermal decomposition is different from one identified earlier during mechanical treatment of the same system. Rehydrogenation of the thermally-decomposed products of LiAlH 4-LiNH2 mixture using high hydrogen pressure (180 bar) and heating (275 °C) yields LiNH2 and amorphous aluminum nitride (AlN). © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","The thermal transformations in the lithium alanate-amide system consisting of lithium aluminum hydride (LiAlH4) and lithium amide (LiNH 2), mixed in a 1:1 M ratio, were investigated using the pressure-composition-temperature analysis, solid-state nuclear magnetic resonance, X-ray powder diffraction, and residual gas analysis. Above 250 °C, additional ∼4 wt% of hydrogen is produced through solid-state reactions among LiNH2, LiH and metallic Al, through the formation of intermetallic Li-Al binary alloy and an unidentified intermediate.",_
!461,"Large quantities of hydrogen (H2) are released at ambient temperatures as a result of mechanical dehydrogenation during ball milling of complex hydride composites such as (LiAlH4+5 wt.% nanometric Fe), (nLiAlH4+LiNH2; n=1, 3, 11.5, 30), (nLiAlH 4+MnCl2; n=1, 3, 8, 13, 30, 63) and (LiNH 2+nMgH2; n=0.5-2.0). For both the (nLiAlH 4+LiNH2) and (LiAlH4+5 wt.% nanometric Fe) composites the second constituent strongly destabilizes LiAlH4 during milling by different mechanisms. For (nLiAlH4+MnCl2) two concurrent mechanisms are observed: (i) a reaction between both constituents during ball milling leading to the formation of LiCl, amorphous Mn and H2, and (ii) a catalytic-like induced decomposition of LiAlH4 into Li 3AlH6, Al and H2. For the (LiNH 2+nMgH2; n=0.5-2.0) composite system, the pathway of hydride reactions depends on the molar ratio n and total milling energy consumed during ball milling. Some composite systems slowly self-discharge H2 at room temperature (RT), 40 and 80°C, after ball milling with an additive. Technical parameters such as specific energy-usable are estimated for LiAlH4-based complex hydride composite systems and are compared with both US DOE hydrogen powered car targets and Li-ion batteries benchmarks. © 2012 Published by Elsevier Ltd.","Some composite systems slowly self-discharge H2 at room temperature (RT), 40 and 80°C, after ball milling with an additive. Technical parameters such as specific energy-usable are estimated for LiAlH4-based complex hydride composite systems and are compared with both US DOE hydrogen powered car targets and Li-ion batteries benchmarks.",_
!462,"The feasibility of scaling up the production of a Mg-based hydride as material for solid state hydrogen storage is demonstrated in the present work. Magnesium hydride, added with a Zr-Ni alloy as catalyst, was treated in an attritor-type ball mill, suitable to process a quantity of 0.5-1 kg of material. SEM-EDS examination showed that after milling the catalyst was well distributed among the magnesium hydride crystallites. Thermodynamic and kinetic properties determined by a Sievert's type apparatus showed that the semi-industrial product kept the main properties of the material prepared at the laboratory scale. The maximum amount of stored hydrogen reached values between 5.3 and 5.6 wt% and the hydriding and dehydriding times were of the order of few minutes at about 300 °C. © 2008 International Association for Hydrogen Energy.","Magnesium hydride, added with a Zr-Ni alloy as catalyst, was treated in an attritor-type ball mill, suitable to process a quantity of 0.5-1 kg of material. The maximum amount of stored hydrogen reached values between 5.3 and 5.6 wt% and the hydriding and dehydriding times were of the order of few minutes at about 300 °C.",_
!463,"A short review of the materials under investigation suitable for solid state hydrogen storage is presented, with emphasis on the experimental activity carried out at the laboratory of Hydrogen Group of Padova University.","A short review of the materials under investigation suitable for solid state hydrogen storage is presented, with emphasis on the experimental activity carried out at the laboratory of Hydrogen Group of Padova University.",_
!464,"In this study, we have developed and characterized various Mg-V-Ni compositions with respect to hydrogen storage. The study was conducted using magnesium as the base material with additions of 5 atomic% of nickel and vanadium in the range of 2.5-10 atomic%. The various compositions were synthesized using high-energy ball milling with different milling times. The compositions were characterized using scanning electron microscopy, energy-dispersive X-ray spectrometry, and X-ray diffraction, and the hydriding-dehydriding characteristics studied using the Sievert method. It was found that the maximum reversible hydrogen storage capacity in the Mg-V-Ni system is 5.71 mass %. Furthermore, it was found that 6 mass% of hydrogen is absorbed within the first 5 min at 210°C. This lowered hydriding temperature is associated with the presence of vanadium as a catalyst. The hydriding enthalpy of the optimized (highest storage capacity) Mg-V-Ni composition has been measured using differential scanning calorimetry as 79.15±3.56 kJ/mol of H2 and the hydriding entropy was obtained as 141.18 ± 6.35 J/mol of H2 K. © 2012 by Begell House, Inc.","In this study, we have developed and characterized various Mg-V-Ni compositions with respect to hydrogen storage. Furthermore, it was found that 6 mass% of hydrogen is absorbed within the first 5 min at 210°C.",_
!465,"Manganese borohydride (Mn(BH 4) 2) is considered to be a high-capacity (∼10 wt %) solid-state hydrogen storage candidate, but so far has not been shown to exhibit reversible hydrogenation. This study presents the calculated crystal structure and electronic structure of Mn(BH 4) 2 from density-functional theory within the generalized gradient approximation and thermodynamic properties from the direct method lattice dynamics. A thermodynamically stable phase of Mn(BH 4) 2 is identified. The calculation of Gibbs energy at finite temperatures suggests that the stable phase is of I4 jm2 symmetry. The formation energy of Mn(BH 4) 2 for the I4 j m2 symmetry solid is -28.93 kJ/f.u. at 0 K including zero-point energy corrections, and the standard state enthalpy of formation is predicted to be -58.89 kJ/f.u. The most feasible dehydrogenation reaction is found to be Mn(BH 4) 2 ) Mn + 2B+ 4H 2, which is an endothermic reaction at decomposition temperature. The spin-polarized electronic density of states shows that manganese borohydride has a half-metallic nature due to the presence of half-filled 3d electrons from Mn. The electronic structure calculations and analysis show that the interaction between Mn atoms and BH4 complexes has an ionic character, while the internal bonding of BH 4 is essentially covalent., © 2009 American Chemical Society.","Manganese borohydride (Mn(BH 4) 2) is considered to be a high-capacity (∼10 wt %) solid-state hydrogen storage candidate, but so far has not been shown to exhibit reversible hydrogenation. at 0 K including zero-point energy corrections, and the standard state enthalpy of formation is predicted to be -58.89 kJ/f.u.",_
!466,"In recent years there has been considerable interest in sodium alanate as a prototypical complex hydride for solid-state hydrogen storage. Much effort has gone into understanding the rate-limiting processes in its hydrogen release and absorption reactions. The diffusion of metal species has been suggested as a possible kinetic bottleneck in Ti-doped materials. In this paper, we outline an approach for calculating the diffusivity of defects in complicated lattices using a combination of first-principles density-functional theory calculations and stochastic kinetic Monte Carlo methods. We apply this methodology to the diffusion of metal defects in NaAlH4 and Na3AlH 6 that have been predicted to exist in large concentrations. We find that of the metal defects that exist in the largest concentrations, a neutral AlH3 vacancy is the most mobile in NaAlH4 (ΔH mig = 0.34 eV, D0 = 1.30 × 10-2 cm 2/s, and DT=400K = 7.55 × 10-7 cm 2/s) and that a negatively charged Na vacancy is the most mobile in Na3AlH6 (ΔHmig = 0.33 eV, D0 = 6.67 × 10-3 cm2/s, and DT=400K = 4.96 × 10-7 cm2/s). At T = 400 K, the calculated diffusion rates are an order of magnitude lower for charged AlH4 vacancies in NaAlH4 (ΔH = 0.44 eV, D0 = 1.41 × 10-2 cm2/s, and DT=400K = 3.92 × 10 -8 cm2/s) and charged Na vacancies in NaAlH4 (ΔH = 0.43 eV, D0 = 2.96 × 10-3 cm 2/s, and DT=400K = 1.19 × 10-8 cm 2/s). This information is necessary for understanding the kinetics of mass transport during the hydrogen release and absorption reactions of NaAlH4. © 2011 American Chemical Society.",Much effort has gone into understanding the rate-limiting processes in its hydrogen release and absorption reactions. The diffusion of metal species has been suggested as a possible kinetic bottleneck in Ti-doped materials.,_
!467,"Our hydrogen-powered lawn mower [Yvon K, Lorenzoni J-L. Hydrogen powered lawn mower. Int J Hydrogen Energy 1993; 18, 345-48] has been operated without major interruption during the past 14 years. The commercial model was originally running on gasoline and was adapted to hydrogen by making small adjustments to the carburettor and by installing a hydrogen reservoir containing solid-state metal hydrides. During the evaluation period the only maintenance work was changing the lubricating oil of the engine once a year, and reactivating the metal hydride powder by external heating after an accidental inlet of air into the reservoir. There occurred no technical failure, and there was no safety incident, neither during operation nor during recharging of hydrogen. This demonstrates that a hydrogen-operated device of this type is mature for use by greater public. Cost and marketing issues are discussed. © 2006 International Association for Hydrogen Energy.","Int J Hydrogen Energy 1993; 18, 345-48] has been operated without major interruption during the past 14 years. The commercial model was originally running on gasoline and was adapted to hydrogen by making small adjustments to the carburettor and by installing a hydrogen reservoir containing solid-state metal hydrides.",_
!468,"The recent advances on the effects of microstructural refinement and various nano-catalytic additives on the hydrogen storage properties of metal and complex hydrides obtained in the last few years in the allied laboratories at the University of Waterloo (Canada) and Military University of Technology (Warsaw, Poland) are critically reviewed in this paper. The research results indicate that microstructural refinement (particle and grain size) induced by ball milling influences quite modestly the hydrogen storage properties of simple metal and complex metal hydrides. On the other hand, the addition of nanometric elemental metals acting as potent catalysts and/or metal halide catalytic precursors brings about profound improvements in the hydrogen absorption/desorption kinetics for simple metal and complex metal hydrides alike. In general, catalytic precursors react with the hydride matrix forming a metal salt and free nanometric or amorphous elemental metals/intermetallics which, in turn, act catalytically. However, these catalysts change only kinetic properties i.e. the hydrogen absorption/desorption rate but they do not change thermodynamics (e.g., enthalpy change of hydrogen sorption reactions). It is shown that a complex metal hydride, LiAlH4, after high energy ball milling with a nanometric Ni metal catalyst and/or MnCl2 catalytic precursor, is able to desorb relatively large quantities of hydrogen at RT, 40 and 80 °C. This kind of behavior is very encouraging for the future development of solid state hydrogen systems. © 2010 by the authors.","The research results indicate that microstructural refinement (particle and grain size) induced by ball milling influences quite modestly the hydrogen storage properties of simple metal and complex metal hydrides. It is shown that a complex metal hydride, LiAlH4, after high energy ball milling with a nanometric Ni metal catalyst and/or MnCl2 catalytic precursor, is able to desorb relatively large quantities of hydrogen at RT, 40 and 80 °C.",_
!469,"In order to enable the commercial acceptance of solid-state hydrogen storage materials and systems it is important to understand the risks associated with the environmental exposure of various materials. In some instances, these materials are sensitive to the environment surrounding the material and the behavior is unique and independent to each material. The development of testing procedures to evaluate a material's behavior with different environmental exposures is a critical need. In some cases material modifications may be needed in order to reduce the risk of environmental exposure. We have redesigned two standardized UN tests for clarity and exactness; the burn rate and self-heating tests. The results of these and other UN tests are shown for ammonia borane, NH 3BH 3, and alane, AlH 3. The burn rate test showed a strong dependence on the preparation method of aluminum hydride as the particle size and trace amounts of solvent greatly influence the test results. The self-heating test for ammonia borane showed a failed test as low as 70 °C in a modified cylindrical form. Finally, gas phase calorimetry was performed and resulted in an exothermic behavior within an air and 30%RH environment. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","The self-heating test for ammonia borane showed a failed test as low as 70 °C in a modified cylindrical form. Finally, gas phase calorimetry was performed and resulted in an exothermic behavior within an air and 30%RH environment.",_
!470,"Hydrogen is important as a new source of energy for automotive applications. It is clear that the key challenge in developing this technology is hydrogen storage. Current methods for hydrogen storage have yet to meet all the demands for onboard applications. High-pressure gas storage or liquefaction cannot fulfill the storage criteria required for on-board storage. Solid-state materials have shown potential advantages for hydrogen storage in comparison to other storage methods. In this article, the most popular solid-state storage materials and methods including carbon based materials, metal hydrides, metal organic frameworks, hollow glass microspheres, capillary arrays, clathrate hydrates, metal nitrides and imides, doped polymer and zeolites, are critically reviewed. The survey shows that most of the materials available with high storage capacity have disadvantages associated with slow kinetics and those materials with fast kinetics have issues with low storage capacity. Most of the chemisorption-based materials are very expensive and in some cases, the hydrogen absorption/desorption phenomena isirreversible. Furthermore, a very high temperature is required to release the adsorbed hydrogen. On the other hand, the main drawback in the case of physisorption-based materials and methods is their lower capacity for hydrogen storage, especially under mild operating conditions. To accomplish the requisite goals, extensive research studies are still required to optimize the critical parameters of such systems, including the safety (to be improved), security (to be available for all), cost (to be lowered), storage capacity (to be increased), and the sorption-desorption kinetics (to be improved). © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.","Hydrogen is important as a new source of energy for automotive applications. Furthermore, a very high temperature is required to release the adsorbed hydrogen.",_
!471,"Owing to their high uptake capacity at low temperature and excellent reversibility kinetics, metal-organic frameworks have attracted considerable attention as potential solid-state hydrogen storage materials. In the last few years, researchers have also identified several strategies for increasing the affinity of these materials towards hydrogen, among which the binding of H 2 to unsaturated metal centers is one of the most promising. Herein, we review the synthetic approaches employed thus far for producing frameworks with exposed metal sites, and summarize the hydrogen uptake capacities and binding energies in these materials. In addition, results from experiments that were used to probe independently the metal-hydrogen interaction in selected materials will be discussed. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.","Owing to their high uptake capacity at low temperature and excellent reversibility kinetics, metal-organic frameworks have attracted considerable attention as potential solid-state hydrogen storage materials. Herein, we review the synthetic approaches employed thus far for producing frameworks with exposed metal sites, and summarize the hydrogen uptake capacities and binding energies in these materials.",_
!472,"Reactive Hydride Composites (RHCs), ball-milled composites of two or more different hydrides, are suggested as an alternative for solid state hydrogen storage. In this work, dehydrogenation of 2NaBH4 + MgH2 system under vacuum was investigated using complementary characterization techniques. At first, thermal programmed desorption of as-milled composite and single compounds was used to identify the temperature range of hydrogen release. RHC samples annealed at various temperatures up to 500 °C were characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. It was found that the dehydrogenation reaction under vacuum is likely to proceed as follows: 2NaBH4 + MgH2 (>250 °C) → 2NaBH4 + 1/2MgH2 + 1/2Mg + 1/2H2 (>350 °C) ↔ 3/2NaBH4 + 1/4MgB2 + 1/2NaH + 3/4Mg + 7/4H2 (>450 °C) → 2Na + B + 1/2Mg + 1/2MgB 2 + 5H2. In addition, presence of NaMgH3 phase suggests the occurrence of secondary reactions. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.","RHC samples annealed at various temperatures up to 500 °C were characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. It was found that the dehydrogenation reaction under vacuum is likely to proceed as follows: 2NaBH4 + MgH2 (>250 °C) → 2NaBH4 + 1/2MgH2 + 1/2Mg + 1/2H2 (>350 °C) ↔ 3/2NaBH4 + 1/4MgB2 + 1/2NaH + 3/4Mg + 7/4H2 (>450 °C) → 2Na + B + 1/2Mg + 1/2MgB 2 + 5H2.",_
!473,"Hydrogen storage in solid hydrides is the most attractive method of on-board hydrogen storage in fuel cell for cars. Mg metal exhibits a high-storage capacity by weight and has been considered a group of potentially attractive candidates for solid-state hydrogen storage. In this study, mechanochemical synthesis of nanocrystalline Mg-based hydrogen storage composites from various starting materials in specialized hydrogen ball mills has been achieved. The reactive synthesis process and the hydrogen desorption behaviors of the composite hydrides were investigated by X-ray diffraction (XRD), thermogravimetric and differential scanning calorimetry (TG-DSC). The results show that nano-sized MgH2 and Mg(AlH4)2 could be directly synthesized by pure Mg and pretreated Al powder, as well as Mg-Li-Al alloy powder. Alloying element Li could remarkably promote the synthesis of magnesium alanate, the product composite hydrides releasing 6.2wt% H2 through multi-step decompositions, of which the starting endothermic peaks are as low as 65 °C. © (2009) Trans Tech Publications, Switzerland.","In this study, mechanochemical synthesis of nanocrystalline Mg-based hydrogen storage composites from various starting materials in specialized hydrogen ball mills has been achieved. The results show that nano-sized MgH2 and Mg(AlH4)2 could be directly synthesized by pure Mg and pretreated Al powder, as well as Mg-Li-Al alloy powder.",_
!474,"There are four R&D programs on hydrogen and fuel cell in Korea. Two of them are supported by MEST (Ministry of Education, Science and Technology) and others are funded by MKE (Ministry of Knowledge Economy). The hydrogen production technologies examined in Korea cover 3 main bases, fossil fuel, renewable energy including photo-catalytic, bio-hydrogen technology, and high temperature gas-cooled reactor. In October 2003, Korean government launched Hydrogen Energy R&D Center (HERC) as a member of the 21st Century Frontier R&D programs supported by the Ministry of Education, Science and Technology (MEST). The HERC has conducted research on the key technologies for the production, storage, and utilization of hydrogen energy for expediting realization of hydrogen economy based on renewable energy sources. The main purposes of this paper are to overview the current status of research programs for hydrogen storage technologies conducted by Hydrogen Energy R&D Center based on the patent applications as well as research topics and to introduce specific achievements in each research program. © 2011 by ASME.","The hydrogen production technologies examined in Korea cover 3 main bases, fossil fuel, renewable energy including photo-catalytic, bio-hydrogen technology, and high temperature gas-cooled reactor. In October 2003, Korean government launched Hydrogen Energy R&D Center (HERC) as a member of the 21st Century Frontier R&D programs supported by the Ministry of Education, Science and Technology (MEST).",_
!475,"We have examined the effect of adding small quantities of Fe, Ni, and Zn, or their dichlorides, on the dehydrogenation temperature of the new quaternary hydride material LiB0.33N0.67H2.67. NiCl2 proved to be an especially effective dehydrogenation promoter. The hydrogen release temperature, represented by the temperature T1/2 at which the hydrogen release reaction is half completed, decreased by ΔT1/2 = -104 °C for 5 wt% NiCl2 addition and by ΔT1/2 = -112 °C for 11 wt% NiCl2 addition compared to that of additive-free LiB0.33N0.67H2.67. This represents a significant improvement over the maximum temperature reduction of ΔT1/2 = -90 °C achieved previously with Pt/Vulcan carbon additive (Pt nanoparticles supported on a Vulcan carbon substrate). Transmission electron microscopy on LiB0.33N0.67H2.67 + 11 wt% NiCl2 revealed uniformly dispersed nanoparticles with diameters less than 8 nm within the LiB0.33N0.67H2.67 matrix, consistent with reduction of the NiCl2 to metallic Ni during synthesis by ball milling. Mass spectrometry of the evolved gas showed that the total amount of NH3 released concurrently during dehydrogenation of LiB0.33N0.67H2.67 + 5 wt% NiCl2 was reduced by an order of magnitude compared to the additive-free material, and by a factor of four compared to LiB0.33N0.67H2.67 + 5 wt% Pt/Vulcan carbon. In contrast to additive-free LiB0.33N0.67H2.67, which melts completely above 190 °C and releases hydrogen from the liquid state only above about 250 °C, hydrogen release from LiB0.33N0.67H2.67 + 5 wt% NiCl2 is accompanied by partial melting above 190 °C plus transformation to a new, hydrogen-poor solid intermediate phase. Addition of 5 wt% FeCl2 gave ΔT1/2 = -36 °C, but Fe, Zn, and ZnCl2 additives did not produce significant improvement. © 2006 Elsevier B.V. All rights reserved.","Transmission electron microscopy on LiB0.33N0.67H2.67 + 11 wt% NiCl2 revealed uniformly dispersed nanoparticles with diameters less than 8 nm within the LiB0.33N0.67H2.67 matrix, consistent with reduction of the NiCl2 to metallic Ni during synthesis by ball milling. Addition of 5 wt% FeCl2 gave ΔT1/2 = -36 °C, but Fe, Zn, and ZnCl2 additives did not produce significant improvement.",_
!476,"In times of severe shortage of fossil fuels new strategies have to be developed to assure future mobility. Fuel cell driven automotives with hydrogen as an energy carrier is one alternative discussed for the substitution of gasoline in the long term. Both the generation as well as the storage of hydrogen are technical challenges which have to be solved before hydrogen technology can be a real alternative for mobile applications. This perspective paper highlights the state-of-the art in the field of hydrogen storage, especially in solids, including the technical limitations. New potential research fields are discussed which may contribute to future energy supply in niche applications. © 2011 The Royal Society of Chemistry.",Both the generation as well as the storage of hydrogen are technical challenges which have to be solved before hydrogen technology can be a real alternative for mobile applications. New potential research fields are discussed which may contribute to future energy supply in niche applications.,_
!477,"Lightweight complex hydrides have attracted attention for their high storage hydrogen capacity. NaAlH4 has been widely studied as a hydrogen storage material for its favorable reversible operating temperature and pressure range for automotive fuel cell applications. The increased understanding of NaAlH4 has led to an expanded search for high capacity materials in mixed alkali and akali/alkaline earth alanates. In this study, promising candidates in the Na-Li-Mg-Al-H system were evaluated using a combination of experimental chemistry, atomic modeling, and thermodynamic modeling. New materials were synthesized using solid state and solution based processing methods. Their hydrogen storage properties were measured experimentally, and the test results were compared with theoretical modeling assessments. © 2007 Elsevier B.V. All rights reserved.",Lightweight complex hydrides have attracted attention for their high storage hydrogen capacity. The increased understanding of NaAlH4 has led to an expanded search for high capacity materials in mixed alkali and akali/alkaline earth alanates.,_
!478,"Hydrogen is expected to play an important role as an energy carrier in a future, more sustainable society. However, its compact, efficient, and safe storage is an unresolved issue. One of the main options is solid-state storage in hydrides. Unfortunately, no binary metal hydride satisfies all requirements regarding storage density and hydrogen release and uptake. Increasingly complex hydride systems are investigated, but high thermodynamic stabilities as well as slow kinetics and poor reversibility are important barriers for practical application. Nanostructuring by ball-milling is an established method to reduce crystallite sizes and increase reaction rates. Since five years attention has also turned to alternative preparation techniques that enable particle sizes below 10 nanometers and are often used in conjunction with porous supports or scaffolds. In this Review we discuss the large impact of nanosizing and -confinement on the hydrogen sorption properties of metal hydrides. We illustrate possible preparation strategies, provide insight into the reasons for changes in kinetics, reversibility and thermodynamics, and highlight important progress in this field. All in all we provide the reader with a clear view of how nanosizing and -confinement can beneficially affect the hydrogen sorption properties of the most prominent materials that are currently considered for solid-state hydrogen storage. Light metal hydrides are an important option for compact, safe, and efficient on-board hydrogen storage. However, slow kinetics, poor reversibility, and low equilibrium pressures hamper their practical application. We review the impact of nanosizing and -confinement; recent strategies with a large impact on the hydrogen sorption properties of relevant light metal hydrides. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.","Since five years attention has also turned to alternative preparation techniques that enable particle sizes below 10 nanometers and are often used in conjunction with porous supports or scaffolds. Light metal hydrides are an important option for compact, safe, and efficient on-board hydrogen storage.",_
!479,"Polymer-stabilized cobalt(0) nanoclusters were prepared from the reduction of cobalt(II) chloride in the presence of poly(N-vinyl-2-pyrrolidone)(PVP) stabilizer in methanol solution. PVP-stabilized cobalt(0) nanoclusters were found to be stable in solution and could be isolated as solid material and characterized by TEM, XPS, FT-IR, and UV-visible electronic absorption spectroscopy. PVP-stabilized cobalt(0) nanoclusters were employed as catalyst in the hydrolysis of sodium borohydride and ammonia-borane, which have been considered as solid-state hydrogen storage materials for portable fuel cell applications. PVP-stabilized cobalt(0) nanoclusters were found to be highly active catalyst in both hydrolysis reactions, even at room temperature. Kinetic studies show that the catalytic hydrolyses of sodium borohydride and ammonia-borane are both first order with respect to catalyst and substrate concentration in aqueous medium. The effect of the NaOH concentration on the catalytic activity of the PVP-stabilized cobalt(0) nanoclusters in the hydrolysis of sodium borohydride was also studied. The activation parameters of these hydrolysis reactions were determined from the evaluation of the kinetic data. The PVP-stabilized cobalt(0) nanoclusters provide a lower activation energy for the hydrolysis of sodium borohydride both in aqueous medium(E a = 63 ± 2 kJ·mol-1) and in basic solution(Ea = 37 ± 2 kJ·mol-1) compared to the value reported for bulk cobalt(Ea = 75 kJ · mol -1). © 2009 American Chemical Society.","PVP-stabilized cobalt(0) nanoclusters were employed as catalyst in the hydrolysis of sodium borohydride and ammonia-borane, which have been considered as solid-state hydrogen storage materials for portable fuel cell applications. PVP-stabilized cobalt(0) nanoclusters were found to be highly active catalyst in both hydrolysis reactions, even at room temperature.",_
!480,"Magnesium may be the most promising solid-state hydrogen storage material owing to its high storage capacity (7.6 wt%) and highest volumetric density (2 times of liquid H2). On the other hand, suffers from its sluggish absorption/desorption characteristics. In the present study, the simple/cost-effective hydriding combustion synthesis (HCS) was used to prepare highly-active Mg-based-samples. The preparative parameters of HCS were varied, and its effects on the micro-structural and hydrogen storage properties were determined. The results and its analysis showed that the simple HCS process possesses a multifaceted dependence on a range of experimental factors and affect the final product. The estimated dependence enabled us to explain the combined effect of individual experimental factors on the prepared samples. The Mg-Ni-C sample prepared at 610°C with 6%wt-nano-Ni and 4 wt%-multi-walled-CNTs as reactants, resulted in sample with a surface area as high as 19.01 m2/g and a desorption capacity of 5.77 wt%, highlighting the promising characteristics of HCS to prepare highly-active Mg-based-materials. Copyright © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","Magnesium may be the most promising solid-state hydrogen storage material owing to its high storage capacity (7.6 wt%) and highest volumetric density (2 times of liquid H2). The Mg-Ni-C sample prepared at 610°C with 6%wt-nano-Ni and 4 wt%-multi-walled-CNTs as reactants, resulted in sample with a surface area as high as 19.01 m2/g and a desorption capacity of 5.77 wt%, highlighting the promising characteristics of HCS to prepare highly-active Mg-based-materials.",_
!481,"EDen is a European project, supported by FP7 - JTI FCH. It aims to develop an innovative embedded system for the storage of energy, thank to combination and thermal integration between a SOFC (capable to work like SOE) and a innovative solid state hydrogen storage tank. In the proposed work, the objective is the optimization through modeling of behavior and physical performance for hydrogen storage solution in solid-state material (Mg-based metal hydrides). The candidate material for hydrogen storage, and final pellet (utilized inside tank) have been defined through the identification of best physics, to better describe gas' diffusion phenomena and thermal exchange inside the storage tank. Copyright © 2013 Delta Energy and Environment.","EDen is a European project, supported by FP7 - JTI FCH. It aims to develop an innovative embedded system for the storage of energy, thank to combination and thermal integration between a SOFC (capable to work like SOE) and a innovative solid state hydrogen storage tank.",_
!482,"Metal hydrides are formed when certain metals or alloys are exposed to hydrogen at favorable temperatures and pressures. In order to sustain the sorption of hydrogen during this exothermic process, the generated heat has to be removed effectively. Release of hydrogen is an endothermic process needing supply of heat to the metal hydride matrix. Depending on the application, the heat transfer medium can be either a liquid or a gas. Reduction of the total weight of hydrogen storage devices is essential toward utilization of hydrogen for mobile and portable applications. While a variety of new storage materials with desirable sorption characteristics are being suggested, optimal thermal design of the storage device remains a major challenge. Lack of thermodynamic, transport, and thermophysical property data of the material particles and of the bed is another drawback which needs to be addressed. © 2012 American Society of Mechanical Engineers.","In order to sustain the sorption of hydrogen during this exothermic process, the generated heat has to be removed effectively. While a variety of new storage materials with desirable sorption characteristics are being suggested, optimal thermal design of the storage device remains a major challenge.",_
!483,"Minimization of total weight is the major criterion in the design of a solid state hydrogen storage device for mobile or portable applications. The design should also address the requirements such as storage capacity, charge/discharge rates, space constraints, coolant temperature and hydrogen supply pressure. To achieve this, one should be able to reliably predict the dynamic performance of the storage device. In this paper, a parametric study of hydrogen sorption in an aircooled annular cylindrical hydrogen storage device with external fins is reported. LaNi5, which has excellent hydrogen storage properties is used as the hydriding material. The influence of different geometric parameters such as hydride bed thickness and fin height, and operational parameters such as hydrogen supply pressure and cooling air temperature are studied.","Minimization of total weight is the major criterion in the design of a solid state hydrogen storage device for mobile or portable applications. LaNi5, which has excellent hydrogen storage properties is used as the hydriding material.",_
!484,"Magnesium is a promising material for solid state hydrogen storage, since it has low cost and its hydride can store reversibly up to 7.6 wt.% of hydrogen. Fast H-sorption kinetics at around 300 °C can be achieved after processing Mg-based mixtures by high energy ball milling (HEBM), which produces nanostructured composite powders. Severe plastic deformation (SPD) processing techniques are being explored as an alternative to HEBM in order to obtain more air-resistant materials and to reduce the time and energy required for processing. In this paper, MgH2 and MgH2-Fe mixtures were severely mechanically processed by extensive cold forging (CF) and cold rolling (CR). A very significant grain refinement (up to 10 nm) was achieved, which is comparable to the values typically obtained after processing by HEBM. Enhanced H-sorption properties were observed for these mechanically processed MgH 2-based nanocomposites in comparison with commercial magnesium hydride. The obtained compacts after CR and CF presents a much lower specific surface area than the ball-milled powders and therefore show higher air-resistance. These results are promising from the point of view of applications since it reveals the potential of the use of low cost mechanical processing routes to produce Mg-based nanomaterials for hydrogen storage. © 2011 Elsevier B.V. All rights reserved.","Fast H-sorption kinetics at around 300 °C can be achieved after processing Mg-based mixtures by high energy ball milling (HEBM), which produces nanostructured composite powders. Enhanced H-sorption properties were observed for these mechanically processed MgH 2-based nanocomposites in comparison with commercial magnesium hydride.",_
!485,"Due to their extensive present, important and versatile potential applications, metal hydrides (MH) are among the most investigated solid-state systems. Theoretical, numerical and experimental studies have provided a considerable knowledge about their structure and properties, but in spite of that, the basic electronic principles of various interactions present in MH have not yet been completely resolved. Even in the simplest MH, i.e. alkali hydrides (Alk-H), some trends in physical properties, and especially their deviations, are not well understood. Similar doubts exist for the alkaline-earth hydride (AlkE-H) series, and are even more pronounced for complex systems, like transition metal-doped AlkE-H, alanates and borohydrides. This work is an attempt of explaining some trends in the physical properties of Alk-H and AlkE-H, employing the Bader analysis of the charge distribution topology evaluated by first-principle all-electron calculations. These results are related to some variables commonly used in the explanation of experimental and calculated results, and are also accompanied by simple tight-binding estimations. Such an approach provides a valuable insight in the characteristics of M-H and H-H interactions in these hydrides, and their possible changes along with external parameters, like temperature, pressure, defect or impurity introduction. The knowledge of these basic interactions and processes taking place in simple MH are essential for the design and optimisation of complex MH-systems interesting for practical hydrogen storage applications. © 2010 World Scientific Publishing Company.","Due to their extensive present, important and versatile potential applications, metal hydrides (MH) are among the most investigated solid-state systems. Theoretical, numerical and experimental studies have provided a considerable knowledge about their structure and properties, but in spite of that, the basic electronic principles of various interactions present in MH have not yet been completely resolved.",_
!486,"This overview will highlight features of the main classes of hydrogen storage materials based on their crystal structures. High-pressure techniques have proven to be a useful approach to rapidly discover light-weight, high-capacity hydrogen storage materials in the solid state. Focus will be on three different materials systems; magnesium-based transition metal hydrides, alanates and borohydrides, their crystal structures and properties, prepared by high-pressure sintering, high-energy ball milling or in a cubic anvil. © 2010 Elsevier Ltd.","High-pressure techniques have proven to be a useful approach to rapidly discover light-weight, high-capacity hydrogen storage materials in the solid state. Focus will be on three different materials systems; magnesium-based transition metal hydrides, alanates and borohydrides, their crystal structures and properties, prepared by high-pressure sintering, high-energy ball milling or in a cubic anvil.",_
!487,"Light metal borohydrides are considered as promising materials for solid state hydrogen storage. Because of the high hydrogen content of 11.5 wt % and the rather low dehydrogenation enthalpy of 32 Kj·mol-1H 2, Ca(BH4)2 is considered to be one of the most interesting compounds in this class of materials. In the present work, the effect of selected TM-fluoride (TM = transition metal) additives on the reversible formation of Ca(BH4)2 was investigated by means of thermovolumetric, calorimetric, Fourier transform infrared spectroscopy, and ex situ, and in situ synchrotron radiation powder X-ray diffraction (SR-PXD) measurements. Furthermore, selected desorbed samples were analyzed by 11B{1H} solid state magic angle spinning nuclear magnetic resonance (MAS NMR). Under the conditions used in this study (145 bar H 2 pressure and 350 °C), TiF4 and NbF5 were the only additives causing partial reversibility. In these two cases, 11B{1H} MAS NMR analyses detected CaB6 and likely CaB12H12 in the dehydrogenation products. Elemental boron was found in the decomposition products of Ca(BH4)2 samples with VF4, TiF3, and VF3. The results indicate an important role of CaB6 for the reversible formation of Ca(BH4)2. © 2011 American Chemical Society.","Light metal borohydrides are considered as promising materials for solid state hydrogen storage. Furthermore, selected desorbed samples were analyzed by 11B{1H} solid state magic angle spinning nuclear magnetic resonance (MAS NMR).",_
!488,"Magnesium hydride (MgH2) is an attractive candidate for solid-state hydrogen storage applications. To improve the kinetics and thermodynamic properties of MgH2 during dehydrogenation- rehydrogenation cycles, a nanostructured MgH2-0.1TiH2 material system prepared by ultrahigh-energy-high-pressure mechanical milling was investigated. High-resolution transmission electron microscope (TEM) and scanning TEM analysis showed that the grain size of the milled MgH 2-0.1TiH2 powder is approximately 5-10 nm with uniform distributions of TiH2 among MgH2 particles. Pressure-composition-temperature (PCT) analysis demonstrated that both the nanosize and the addition of TiH2 contributed to the significant improvement of the kinetics of dehydrogenation and hydrogenation compared to commercial MgH2. More importantly, PCT cycle analysis demonstrated that the MgH2-0.1TiH2 material system showed excellent cycle stability. The results also showed that the ΔH value for the dehydrogenation of nanostructured MgH2-0.1TiH2 is significantly lower than that of commercial MgH2. However, the ΔS value of the reaction was also lower, which results in minimum net effects of the nanosize and the addition of TiH2 on the equilibrium pressure of dehydrogenation reaction of MgH2. © 2009 American Chemical Society.","To improve the kinetics and thermodynamic properties of MgH2 during dehydrogenation- rehydrogenation cycles, a nanostructured MgH2-0.1TiH2 material system prepared by ultrahigh-energy-high-pressure mechanical milling was investigated. High-resolution transmission electron microscope (TEM) and scanning TEM analysis showed that the grain size of the milled MgH 2-0.1TiH2 powder is approximately 5-10 nm with uniform distributions of TiH2 among MgH2 particles.",_
!489,"Metal hydrides are one of the most promising technologies in the field of hydrogen storage due to their high volumetric storage density. Important reaction steps take place at the very surface of the solid during hydrogen absorption. Since these reaction steps are drastically influenced by the properties and potential contamination of the solid, it is very important to understand the characteristics of the surface, and a variety of analytical methods are required to achieve this. In this work, a TiMn2-type metal hydride alloy is investigated by means of high-pressure activation measurements, X-ray photoelectron spectroscopy (XPS), secondary neutral mass spectrometry (SNMS) and thermal desorption mass spectrometry (TDMS). In particular, TDMS is an analytical tool that, in contrast to SIMS or SNMS, allows the hydrogen content in a metal to be quantified. Furthermore, it allows the activation energy for desorption to be determined from TDMS profiles; the method used to achieve this is presented here in detail. In the results section, it is shown that the oxide layer formed during manufacture and long-term storage prevents any hydrogen from being absorbed, and so an activation process is required. XPS measurements show the oxide states of the main alloy elements, and a layer 18 nm thick is determined via SNMS. Furthermore, defined oxide layers are produced and characterized in UHV using XPS. The influence of these thin oxide layers on the hydrogen sorption process is examined using TDMS. Finally, the activation energy of desorption is determined for the investigated alloy using the method presented here, and values of 46 kJ/mol for hydrogen sorbed in UHV and 103 kJ/mol for hydrogen originating from the manufacturing process are obtained. © 2009 Springer-Verlag.","In this work, a TiMn2-type metal hydride alloy is investigated by means of high-pressure activation measurements, X-ray photoelectron spectroscopy (XPS), secondary neutral mass spectrometry (SNMS) and thermal desorption mass spectrometry (TDMS). In the results section, it is shown that the oxide layer formed during manufacture and long-term storage prevents any hydrogen from being absorbed, and so an activation process is required.",_
!490,Hydrogenation properties and mechanical stability of pellets made starting from compressed ball-milled MgH2 powders mixed with catalysts (Nb2O5 and graphite) and a binding agent (aluminium powder) have been investigated. Structural characterization with X-ray diffraction and gas-solid reaction kinetic and thermodynamic tests with a Sievert's apparatus have been done on the samples up to 50 hydrogen absorption/desorption (a/d) cycles. The best cycling behaviour and mechanical strength stability have been observed for pellets of catalysed MgH2 powders added with 5 wt% aluminium annealed in vacuum at 450 °C before starting the a/d cycles. This mechanical stability to cycles has been attributed to the formation of a solid solution of aluminium in magnesium. © 2010 Professor T. Nejat Veziroglu.,Structural characterization with X-ray diffraction and gas-solid reaction kinetic and thermodynamic tests with a Sievert's apparatus have been done on the samples up to 50 hydrogen absorption/desorption (a/d) cycles. The best cycling behaviour and mechanical strength stability have been observed for pellets of catalysed MgH2 powders added with 5 wt% aluminium annealed in vacuum at 450 °C before starting the a/d cycles.,_
!491,"LiAlH 4 containing 5 wt.% of nanometric Fe (n-Fe) shows a profound mechanical dehydrogenation by continuously desorbing hydrogen (H 2) during high energy ball milling reaching ∼3.5 wt.% H 2 after 5 h of milling. In contrast, no H 2 desorption is observed during low energy milling of LiAlH 4 containing n-Fe. Similarly, no H 2 desorption occurs during high energy ball milling for LiAlH 4 containing micrometric Fe (μ-Fe) and, for comparison, both the micrometric and nanometric Ni (μ-Ni and n-Ni) additive. X-ray diffraction studies show that ball milling results in a varying degree of the lattice expansion of LiAlH 4 for both the Fe and Ni additives. A volumetric lattice expansion larger than 1% results in the profound destabilization of LiAlH 4 accompanied by continuous H 2 desorption during milling according to reaction: LiAlH 4 (solid) → 1/3Li 3AlH 6 + 2/3Al + H 2. It is hypothesized that the Fe ions are able to dissolve in the lattice of LiAlH 4 by the action of mechanical energy, replacing the Al ions and forming a substitutional solid solution. The quantity of dissolved metal ions depends primarily on the total energy of milling per unit mass of powder generated within a prescribed milling time, the type of additive ion e.g. Fe vs. Ni and on the particle size (micrometric vs. nanometric) of metal additive. For thermal dehydrogenation the average apparent activation energy of Stage I (LiAlH 4 (solid) → 1/3Li 3AlH 6 + 2/3Al + H 2) is reduced from the range 76 to 96 kJ/mol for the μ-Fe additive to about 60 kJ/mol for the n-Fe additive. For Stage II dehydrogenation (1/3Li 3AlH 6 → LiH+1/3Al + 0.5H 2) the average apparent activation energy is within the range 77-93 kJ/mol, regardless of the particle size of the Fe additive (μ-Fe vs. n-Fe). The n-Fe and n-Ni additives, the latter used for comparison, provide nearly identical enhancement of dehydrogenation rate during isothermal dehydrogenation at 100 °C. Ball milled (LiAlH 4 + 5 wt.% n-Fe) slowly self-discharges up to ∼5 wt.% H 2 during storage at room temperature (RT), 40 and 80 °C. Fully dehydrogenated (LiAlH 4 + 5 wt.% n-Fe) has been partially rehydrogenated up to 0.5 wt.% H 2 under 100 bar/160°C/24 h. However, the rehydrogenation parameters are not optimized yet. © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.","Ball milled (LiAlH 4 + 5 wt.% n-Fe) slowly self-discharges up to ∼5 wt.% H 2 during storage at room temperature (RT), 40 and 80 °C. Fully dehydrogenated (LiAlH 4 + 5 wt.% n-Fe) has been partially rehydrogenated up to 0.5 wt.% H 2 under 100 bar/160°C/24 h. However, the rehydrogenation parameters are not optimized yet.",_
!492,"NaBH 4 is considered as a promising candidate material for solid-state hydrogen storage due to its high hydrogen content of 10.6 wt %. However, its practical use is hampered by its high thermodynamic stability and slow H-exchange kinetics. In the present work, the effects of Ti-based additives, including Ti, TiH 2, and TiF 3, on the dehydrogenation and rehydrogenation of NaBH 4 (NaH+B) were investigated. It was revealed that all of the titanium-based additives were effective in improving the hydrogen desorption and absorption reactions of NaBH 4, and, among them, TiF 3 possessed the highest catalytic activity. The whole dehydrogenation process for the NaBH 4-0.05TiF 3 sample can be regarded as a two-step process: (i) a preferential reaction (3NaBH 4 + TiF 3 → 3NaF + TiB 2 + B + 6H 2) occurring at around 300 °C, and (ii) the formation of Ti- and F-containing species catalyze the dehydrogenation of the remaining NaBH 4. It was also indicated that the F anion can substitute for anionic H in NaH to form NaF 1-xH x in the case of NaH-B-0.05TiF 3 during the hydrogenation process. Therefore, the observed promotion effect of TiF 3 on the reversible dehydrogenation of NaBH 4 should be understood as arising from the combined effects of active Ti- and F-containing species. Also, FTIR spectroscopy confirmed the presence of amorphous Na 2B 12H 12, in both the dehydrogenated and the rehydrogenated states, which may play a role in the partial dehydrogenation and reversibility observed in NaBH 4 with and without catalyst doping. © 2011 American Chemical Society.","NaBH 4 is considered as a promising candidate material for solid-state hydrogen storage due to its high hydrogen content of 10.6 wt %. It was revealed that all of the titanium-based additives were effective in improving the hydrogen desorption and absorption reactions of NaBH 4, and, among them, TiF 3 possessed the highest catalytic activity.",_
!493,"A Mg-Zr thin film is prepared on a glass substrate by co-sputtering of Mg and Zr targets and in situ sputtering of a thin Pd overlayer. The structural and optical properties of Mg-Zr and Mg-Zr-H thin film are investigated induced by hydrogen absorption and/or desorption at room temperature. Optical transmission and reflection data indicated that Mg-Zr-H thin film is the color-neutral in the visible range with chromaticity coordinates of x = 0.3566 and y = 0.3430. The formation of the ternary hydride Mg 0.82Zr 0.18H 2 is confirmed in an Mg-rich Mg-Zr solid solution thin film in the hydride state. The hydrogen insertion and extraction occurs in fcc lattice structure. Because the volume change according to hydrogenation and dehydrogenation, the switching durability is much better than that of the switchable mirror using Mg-Ni alloy. © 2011 Elsevier B.V. All rights reserved.",Optical transmission and reflection data indicated that Mg-Zr-H thin film is the color-neutral in the visible range with chromaticity coordinates of x = 0.3566 and y = 0.3430. The hydrogen insertion and extraction occurs in fcc lattice structure.,_
!494,"The motorcycle plays an important role in the life for the people of Taiwan. However, the motorcycles' emissions are the main moving air pollution sources. Therefore, it's important to develop more efficient combustion technology in order to save energy and reduce air pollution. In this paper, a novel technology of hydrogen-gasoline compound fuel is developed. Hydrogen gas is released from solid state hydrogen storage tank and then mixed with the incoming gasoline. The intake valve in manifold sucks the hydrogen-gasoline compound fuel into the cylinder for combustion. A series of performance test is conducted by motorcycle chassis dynamometers. The results reveal that this technology can increase the power and torque, and decrease fuel consumption per kilo-power due to promote combustion efficiency. In addition, the hydrogen has greater heat value, so the oil temperature and sparkplug temperature increase. This technique can reduce CO and HC, but increase CO2 and NOx. The engine performance is improved at rarefied hydrogen-gasoline compound fuel. Therefore, the engine performance with M.J. #98 is better than that with M.J. #110. This technique can achieve energy saving and environment-friendly purpose. Copyright © 2012, IGI Global.","In this paper, a novel technology of hydrogen-gasoline compound fuel is developed. A series of performance test is conducted by motorcycle chassis dynamometers.",_
!495,"A comprehensive study of the decomposition behavior of as received and mechanically (ball) milled LiAlH4 has been carried out using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and volumetric hydrogen desorption in a Sieverts-type apparatus. Alfa Aesar LiAlH4 powder investigated in this work has the average particle size of 9.9 ± 5.2 μm as compared to 50-150 μm for Sigma-Aldrich LiAlH4 investigated by Ares et al. [9]. High energy ball milling reduced the particle size of the present LiAlH4 to 2.8 ± 2.3 μm. In general, comparing the results of our microstructural studies with those reported by Ares et al. [9] it is clear that the morphology, microstructure and chemistry of LiAlH4 can be very dissimilar depending on the supplier from which LiAlH4 powder was purchased. We do not observe a partial decomposition of LiAlH4 during milling up to 5 h under high energy impact mode. The observed melting of LiAlH4 in a DSC test is a very volatile event where the liquid LiAlH4 starts foaming and flowing out of the alumina crucible. After completion of solidification and desorption at temperatures above melting the powder resembles a lava rock. A thermal sectioning in DSC tests at pre-determined temperatures and subsequent XRD studies show that LiAlH4 starts decomposing into Li 3AlH6 immediately after melting. Li3AlH 6 seems to be already solidified before it starts decomposing in the next stage. All volumetric desorption curves at the 120-300 °C range clearly exhibit a two-stage desorption process, Stage I and II. As received LiAlH 4 is able, in a fully solid state, to desorb at 120 °C under pressure of 0.1 MPa H2 (atmospheric) as much as 7.1 wt.%H2 within ∼259,000 s (∼72 h), i.e. ∼93% of the purity-corrected H 2 content from the reactions in Stage I (LiAlH4(s) → (1/3)Li3AlH6(s) + (2/3)Al(s) + H2) and Stage II ((1/3)Li3AlH6(s) → LiH + (1/3)Al + 0.5H 2). The apparent activation energy for Stage I and II for unmilled LiAlH4 is equal to ∼111 and ∼100 kJ/mol, respectively. For the ball milled LiAlH4 the apparent activation energy for Stage I and II is slightly lower ∼92.5 and ∼92 kJ/mol, respectively. The water absorption up to 11.7% due to exposure to air for 1 h does not change in any drastic way the hydrogen desorption rate of ball milled LiAlH4 in Stage I. Flammability tests show that the ball milled LiAlH4 powder does not self-ignite on contact with air but can only be ignited by scraping the cylinder walls with a metal tool and then the powder burns with an open flame. © 2010 Elsevier B.V. All rights reserved.",We do not observe a partial decomposition of LiAlH4 during milling up to 5 h under high energy impact mode. A thermal sectioning in DSC tests at pre-determined temperatures and subsequent XRD studies show that LiAlH4 starts decomposing into Li 3AlH6 immediately after melting.,_
!496,"Multiple reaction mixtures with different composition ratios of MCl 3-LiBH 4 (M = La, Gd) were studied by mechano-chemical synthesis, yielding two new bimetallic borohydride chlorides, LiM(BH 4) 3Cl (M = La, Gd). The Gd-containing phase was obtained only after annealing the ball-milled mixture. Additionally, a solvent extracted sample of Gd(BH 4) 3 was studied to gain insight into the transformation from Gd(BH 4) 3 to LiGd(BH 4) 3Cl. The novel compounds were investigated using in situ synchrotron radiation powder X-ray diffraction, thermal analysis combined with mass spectroscopy, Sieverts measurements, Fourier transform infrared spectroscopy, and electrochemical impedance spectroscopy. The two new compounds, LiLa(BH 4) 3Cl and LiGd(BH 4) 3Cl, have high lithium ion conductivities of 2.3 ×10 -4 and 3.5 ×10 -4 S•cm -1 (T = 20 °C) and high hydrogen densities of ρ m = 5.36 and 4.95 wt % H 2, and both compounds crystallize in the cubic crystal system (space group I-43m) with unit cell parameter a = 11.7955(1) and a = 11.5627(1) Å, respectively. The structures contain isolated tetranuclear anionic clusters [M 4Cl 4(BH 4) 12] 4- with distorted cubane M 4Cl 4 cores M = La or Gd. Each lanthanide atom coordinates three chloride ions and three borohydride groups, thus completing the coordination environment to an octahedron. The Li + ions are disordered on 2/3 of the 12d Wyckoff site, which agrees well with the very high lithium ion conductivities. The conductivity is purely ionic, as electronic conductivities were measured to only 1.4 ×10 -8 and 9 ×10 -8 S•cm -1 at T = 20 °C for LiLa(BH 4) 3Cl and LiGd(BH 4) 3Cl, respectively. In situ synchrotron radiation powder X-ray diffraction (SR-PXD) reveals that the decomposition products at 300 °C consist of LaB 6/LaH 2 or GdB 4/GdH 2 and LiCl. The size of the rare-earth metal atom is shown to be crucial for the formation and stability of the borohydride phases in MCl 3-LiBH 4 systems. © 2012 American Chemical Society.","Multiple reaction mixtures with different composition ratios of MCl 3-LiBH 4 (M = La, Gd) were studied by mechano-chemical synthesis, yielding two new bimetallic borohydride chlorides, LiM(BH 4) 3Cl (M = La, Gd). In situ synchrotron radiation powder X-ray diffraction (SR-PXD) reveals that the decomposition products at 300 °C consist of LaB 6/LaH 2 or GdB 4/GdH 2 and LiCl.",_
!497,"The rapidly depleting petroleum feed stocks and increasing green house gas emissions around the world has necessitated a search for alternative renewable energy sources. Hydrogen with molecular weight of 2.016 g/mol and high chemical energy per mass equal to 142 MJ/kg has clearly emerged as an alternative to hydrocarbon fuels. Means for safe and cost effective storage are needed for widespread usage of hydrogen as a fuel. Chemical storage is the one of the safer ways to store hydrogen compared to compressed and liquefied hydrogen. It involves storing hydrogen in chemical bonds in molecules and materials where an on-board reaction is used to release hydrogen. Ammonia-borane, (AB, H 3N·BH3) with a potential capacity of 19.6 wt% is considered a very promising solid state hydrogen storage material. It is thermally stable at ambient temperatures. There are two major routes for the generation of H2 from AB: catalytic hydrolysis/alcoholysis and catalytic thermal decomposition. There has been a flurry of research activity on the generation of H2 from AB recently. The present review deals with an overview of our efforts in developing cost-effective nanocatalysts for hydrogen generation from ammonia borane in protic solvents.",The rapidly depleting petroleum feed stocks and increasing green house gas emissions around the world has necessitated a search for alternative renewable energy sources. The present review deals with an overview of our efforts in developing cost-effective nanocatalysts for hydrogen generation from ammonia borane in protic solvents.,_
!498,"This paper discusses the results of an experimental program carried out to determine dust cloud deflagration parameters of selected solid-state hydrogen storage materials, including complex metal hydrides (sodium alanate and lithium borohydride/magnesium hydride mixture), chemical hydrides (alane and ammonia borane) and activated carbon (Maxsorb, AX-21). The measured parameters include maximum deflagration pressure rise, maximum rate of pressure rise, minimum ignition temperature, minimum ignition energy and minimum explosible concentration. The calculated explosion indexes include volume-normalized maximum rate of pressure rise (KSt), explosion severity (ES) and ignition sensitivity (IS). The deflagration parameters of Pittsburgh seam coal dust and Lycopodium spores (reference materials) are also measured. The results show that activated carbon is the safest hydrogen storage media among the examined materials. Ammonia borane is unsafe to use because of the high explosibility of its dust. The core insights of this contribution are useful for quantifying the risks associated with use of these materials for on-board systems in light-duty fuel cell-powered vehicles and for supporting the development of hydrogen safety codes and standards. These insights are also critical for designing adequate safety features such as explosion relief venting and isolation devices and for supplementing missing data in materials safety data sheets. © 2012 Elsevier Ltd.",The deflagration parameters of Pittsburgh seam coal dust and Lycopodium spores (reference materials) are also measured. These insights are also critical for designing adequate safety features such as explosion relief venting and isolation devices and for supplementing missing data in materials safety data sheets.,_
!499,"Hydrogen interaction of porphyrin hetero-pairs has been studied by differential scanning calorimetry (DSC). Aggregates were prepared by spontaneous aggregation of water soluble anionic porphyrins meso-tetra(4-carboxyphenyl) porphine (TCPP) and meso-tetra(4-sulfonatophenyl)porphine (TPPS) with cationic meso-tetra-p-trimethylaminophenyl porphine tetrachloride (TAP). Aggregate formation in solution was investigated via UV-visible spectroscopy at different pH ranges. At neutral to basic conditions, porphyrin pairs formed partially soluble hetero H-aggregates and at low pH, soluble homo J-aggregates was formed. H-aggregates were isolated by centrifuging and freeze-drying. The obtained solids were studied by X-ray powder diffraction. Thermal stability of dry aggregates was determined by thermogravimetric analysis. The TCPP-TAP hetero aggregates exhibited hydrogen uptake between 80 °C and 250 °C. The amount of hydrogen absorbed by the sample corresponds to 0.29% by weight, indicating a potential use of such materials as a solid state hydrogen storage medium. Copyright © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.",Hydrogen interaction of porphyrin hetero-pairs has been studied by differential scanning calorimetry (DSC). Aggregate formation in solution was investigated via UV-visible spectroscopy at different pH ranges.,_
!500,"The onboard hydrogen storage is the main challenge to achieve a hydrogen-based economy. The most promising way is the solid-state storage, and the best candidates as storage media are currently considered the complex hydrides. In the present work we review recent results obtained by anelastic spectroscopy studies on these materials. © 2009 Elsevier B.V. All rights reserved.",The onboard hydrogen storage is the main challenge to achieve a hydrogen-based economy. In the present work we review recent results obtained by anelastic spectroscopy studies on these materials.,_
!501,"The state of the titanium catalyst species formed upon doping and hydrogen cycling of NaAlH4 with Ti-catalysts was studied by X-ray diffraction analysis. After doping with TiCl3, Ti is present as an hcp-Ti(Al) solid solution, while for the Ti(OBu)4 doped system, Ti exists as an XRD-amorphous phase. Cycling of hydrogen for 1.5 times results in transformation of these initially different Ti compounds into similar compounds, whose composition is dependent on the temperature. Thus, if low temperatures were used during the cycling process (up to 175 °C) an amorphous Al-Ti alloy formed, while upon using high temperatures (200 °C and higher) Ti was present as an AlxTi intermetallic. Correlation of the XRD and hydrogen desorption curves shows that the most active catalyst species in the present system is the amorphous Al-Ti alloy, whereas a decreased catalytic activity is found for the AlxTi intermetallic. © 2004 Elsevier B.V. All rights reserved.","Cycling of hydrogen for 1.5 times results in transformation of these initially different Ti compounds into similar compounds, whose composition is dependent on the temperature. Thus, if low temperatures were used during the cycling process (up to 175 °C) an amorphous Al-Ti alloy formed, while upon using high temperatures (200 °C and higher) Ti was present as an AlxTi intermetallic.",_
!502,"In this work, effects of partial substitution of Mg, Ni with AB2 in Mg-based alloy and subsequent surface modification by further ball-milling with carbon nanotubes (CNTs) on electrochemical properties were investigated. Mg1.9(AB2)0.1Ni0.8 (AB 2=LaNi2, LaNiCo and LaNiMn) alloys were prepared by solid-state diffusion method, the nanocrystalline Mg-based alloys were prepared by ball-milling the mixture of obtained Mg1.9(AB2) 0.1Ni0.8 alloys and nickel powder. It was found that the electrochemical capacities of nanocrystalline Mg1.9(AB 2)0.1Ni1.8 alloys were measured to be 460-490mAh/g. The nanocrystalline Mg-based alloys containing carbon nanotubes (10wt.%) obtained by ball-milling after 60min were demonstrated to show improved electrochemical properties with respect to the original nanocrystalline Mg-based alloys. The electrochemical reaction activity was detected by electrochemical impedance spectra (EIS). Raman and X-ray photoelectron spectroscopy (XPS) proved the interaction between Mg1.9(AB 2)0.1Ni1.8 alloys and carbon nanotubes after ball-milling, which resulted in an increase in the surface Ni/Mg ratio. © 2003 Elsevier B.V. All rights reserved.","In this work, effects of partial substitution of Mg, Ni with AB2 in Mg-based alloy and subsequent surface modification by further ball-milling with carbon nanotubes (CNTs) on electrochemical properties were investigated. It was found that the electrochemical capacities of nanocrystalline Mg1.9(AB 2)0.1Ni1.8 alloys were measured to be 460-490mAh/g.",_
!503,"The reaction of gaseous hydrogen with hydride-forming metals and alloys often involves a hydride layer formed on the metallic surface. Under proper steady state conditions, this layer is moving into the bulk metal, retaining constant thickness and velocity. In this work, the kinetics of the moving hydride layer is analyzed, using a model combining the four main sequential steps: adsorption (chemisorption), penetration, diffusion and reaction, in which the hydrogen is transferred from the gas phase into the reaction site. The model yields the rate of absorption during the steady state hydriding process (proportional to the hydride layer velocity) as a function of the pressure, the rate constants of the system (adsorption, desorption, penetration, decomposition, diffusion and interface emission) and the critical concentrations of hydrogen in the hydride, Cmax, Cp and Cmin (the last is associated with the equilibrium absorption pressure Peq). According to the model, for sufficiently high pressures, the rate is pressure-independent. A simple expression for the pressure independent rate is derived. The conditions leading to rates limited by one of the four sequential steps are analyzed and demonstrated. Relatively simple expressions are derived for the rate's pressure dependence. It is shown that for the interface and diffusion controlled cases the general pressure dependence is of the form: Rate-1∝[(P/Peq)1/2-1]-1. For the adsorption controlled case the pressure dependence is Rate∝(P-Peq). Based on the model, a numerical procedure is proposed for a system, removed from an initial steady state, describing the time-dependent approach to the new steady state determined by the applied change. The model is successfully tested for a real case, the uranium-hydrogen system, which is shown to obey the interface control rate equations.","Under proper steady state conditions, this layer is moving into the bulk metal, retaining constant thickness and velocity. A simple expression for the pressure independent rate is derived.",_
!504,"A hydrogen engine-fuel system is being developed as an alternative for powering underground mining machinery. A diesel was converted to a spark-ignited hydrogen engine and operated with a metal hydride, solid-state hydrogen storage system. Performance and emissions data show that hydrogen can be used as an ultralow emission fuel for underground mining. A special method of fuel control has overcome abnormal combustion problems frequently experienced with hydrogen fuel. The turbocharged, after-cooled engine maintains NOX emissions (the only significant pollutant) below 0.7 gram per kilowatt-hour. Power and fuel consumption are comparable to the naturally aspirated, prechambered diesel version of the engine. Hydrogen fuel is released from a metal hydride storage container by heat from the engine coolant. Through proper design, hydride containment can limit the leakage of hydrogen, in a worst-case accident, to acceptable levels. Copyright © 1984 Society of Automotive Engineers, Inc.","Performance and emissions data show that hydrogen can be used as an ultralow emission fuel for underground mining. Through proper design, hydride containment can limit the leakage of hydrogen, in a worst-case accident, to acceptable levels.",_
!505,"The effect of sequential and continuous high-energy impact mode in the magneto-mill Uni-Ball-Mill 5 on the mechano-chemical synthesis of nanostructured ternary complex hydride Mg2FeH6 was studied by controlled reactive mechanical alloying (CRMA). In the sequential mode the milling vial was periodically opened under a protective gas and samples of the milled powder were extracted for microstructural examination whereas during continuous CRMA the vial was never opened up to 270 h duration. MgO was detected by XRD in sequentially milled powders while no MgO was detected in the continuously milled powder. The abundance of the nanostructured ternary complex hydride Mg 2FeH6, produced during sequential milling, and estimated from DSC reached ∼44 wt.% after 188 h, and afterwards it slightly decreased to ∼42 wt.% after 210 and 270 h. In contrast, the DSC yield of Mg 2FeH6 after continuous CRMA for 270 h was ∼57 wt.%. Much higher yield after continuous milling is attributed to the absence of MgO. This behavior provides strong evidence that MgO is a primary factor suppressing formation of Mg2FeH6. The DSC hydrogen desorption onset temperatures are close to 200 °C while the desorption peak temperatures for all powders are below 300 °C and the desorption process is completed within the range 10-20 min. Within the investigated nanograin size range of ∼5-13 nm, the DSC desorption onset and peak temperatures of β-MgH2 and Mg2FeH6 do not exhibit any trend with nanograin (crystallite) size of hydrides. TPD hydrogen desorption peaks from the powders containing a single ternary complex hydride Mg2FeH6, are very narrow, which indicates the presence of small but well-crystallized hydride particles. Their narrowness provides good evidence that the phase composition, bulk hydrogen distribution and hydride particle size distribution are very homogeneous. The overall amount of hydrogen desorbed in TPD from single-hydride Mg2FeH6 powders is somewhat higher than that observed in DSC and TGA desorption. The powder milled sequentially for 270 h and desorbed in a Sieverts-type apparatus at 250 and 290 °C, yielded about a half of the hydrogen content obtained during DSC and TGA tests. No desorption of hydrogen was detected in a Sieverts-type apparatus at 250 and 290 °C after 128 and 70 min, respectively, from the powder continuously milled for 270 h. The latter easily desorbed 3.13 and 2.83 wt.% hydrogen in DSC and TGA tests, respectively. © 2004 Elsevier B.V. All rights reserved.",Much higher yield after continuous milling is attributed to the absence of MgO. This behavior provides strong evidence that MgO is a primary factor suppressing formation of Mg2FeH6.,_
!506,"Various properties of metal hydrides and their use in energy storage and conversion systems are discussed. Metal hydrides can be classified in terms of the hydrogen bonding to the metal. For the alloy side of the hydride family, hydrogen is usually bound in the interstitial sites in a metallic state with usually minor distortions of generally stable H-free alloy structure. Metal hydrides are being considered for applications involving the absorption and desorption of hydrogen gas, as many of them can readily absorb and desorb hydrogen gas around room temperature and near atmospheric H 2 pressure.","For the alloy side of the hydride family, hydrogen is usually bound in the interstitial sites in a metallic state with usually minor distortions of generally stable H-free alloy structure. Metal hydrides are being considered for applications involving the absorption and desorption of hydrogen gas, as many of them can readily absorb and desorb hydrogen gas around room temperature and near atmospheric H 2 pressure.",_
!507,"The PuNi3-type intermetallic compounds LaNi3, CaNi3, La0.5Ca0.5Ni3, LaCaMgNi9, La0.5Ca1.5MgNi9, CaTiMgNi9, LaCaMgNi6Al3 and LaCaMgNi6Mn3 have been prepared using a powder-metallurgy-sintering method. The hydrogenation behaviour of these materials has been studied through the gas-solid reaction. The as-prepared compounds were easily activated at room temperature under a hydrogen pressure of 3.3 MPa. The pressure-composition-temperature (P-C-T) curves show a single plateau region with the exception of LaNi3-H, which shows no plateau, and La0.5Ca1.5MgNi9-H, which shows two plateaus. All of these alloys can absorb/desorb hydrogen by 1.8 wt.% under the conditions studied. X-ray diffraction (XRD) analysis reveals that LaNi3H4.5 is in the amorphous state, and the other hydrides are accompanied by different expansions of the unit cell volume of the host alloy.","The PuNi3-type intermetallic compounds LaNi3, CaNi3, La0.5Ca0.5Ni3, LaCaMgNi9, La0.5Ca1.5MgNi9, CaTiMgNi9, LaCaMgNi6Al3 and LaCaMgNi6Mn3 have been prepared using a powder-metallurgy-sintering method. The as-prepared compounds were easily activated at room temperature under a hydrogen pressure of 3.3 MPa.",_
!508,"The International Energy Agency Agreement on the Production and Utilization of Hydrogen is marking its 25th anniversary. This summarizes the R&D activities in currently active Annex 17 - Solid and Liquid State Hydrogen Storage Materials. Task 17 was chartered in 2001 and sets as its main target the development of reversible hydrogen storage media capable of delivering 5 wt.% H at less than 80°C. Eleven countries and the EC are official participants: Australia, Canada, European Commission, Japan, Italy, Lithuania, Norway, Spain, Sweden, Switzerland, the United Kingdom and the United States. The eleven national participations are represented by 33 research centers representing universities, national laboratories and industries. Internationally collaborative R&D are being performed under about 32 projects divided among three categories of H-storage media: hydrides, carbon and combined hydrides plus carbon. Included in the Task 17 activities is the IEA/DOE/SNL Hydride Information Center, an extensive series of online databases of hydride properties and applications (hydpark.ca.sandia.gov).","This summarizes the R&D activities in currently active Annex 17 - Solid and Liquid State Hydrogen Storage Materials. Internationally collaborative R&D are being performed under about 32 projects divided among three categories of H-storage media: hydrides, carbon and combined hydrides plus carbon.",_
!509,"The H2Fuel Bus is the world's first hydrogen-fueled electric hybrid transit bus (see Figure1.). It was a project developed through a public/private partnership involving several leading technological and industrial organizations, with primary funding by the Department of Energy (DOE). The primary goals of the project were to gain valuable information on the technical readiness and economic viability of hydrogen fueled buses and to enhance the public awareness and acceptance of emerging hydrogen technologies. The bus completed its field-testing and was placed into public service on September 4, 1998 by Augusta Public Transit in Augusta, Georgia. The bus employs a hybrid Internal Combustion (IC) engine/generator and battery powered electric drive system, with onboard storage of hydrogen in metal hydride beds. The initial operating results demonstrated an overall energy efficiency (miles/BTU) twice the range of a similar diesel-fueled bus, while doubling the range of an all-electric vehicle by providing in-transit recharging of the batteries. Subsequent data showed that the power controller was not optimized for maximum battery life and, therefore, some efficiency was lost. Correction of that condition would provide a daily range of at least 120 miles in a hybrid hydrogen/electric-operating mode. The project developed reduced engine tail-pipe emissions, with NOx measured at less than 0.2 ppm. In addition todemonstrating the inherent safety of a solid-state hydrogen storage system, the project also addressed permit, liability, and safety issues, including a safety risk assessment of the metal hydride storage system. State-of-the-art technology in battery system management was likewise demonstrated. Copyright © 1999 Society of Automotive Engineers, Inc.","The bus employs a hybrid Internal Combustion (IC) engine/generator and battery powered electric drive system, with onboard storage of hydrogen in metal hydride beds. The project developed reduced engine tail-pipe emissions, with NOx measured at less than 0.2 ppm.",_
!510,"The processes occurring in the course of two sequential hydrogen discharging and recharging cycles of Ti-doped sodium alanate were investigated in parallel using XRD analysis and solid-state NMR spectroscopy. Both methods demonstrate that in hydrogen storage cycles (Eq. (1)) the majority phases involved are NaAlH4, Na3AlH6, Al and NaH. Only traces of other, as yet unidentified phases are observed, one of which has been tentatively assigned to an Al-Ti alloy on the basis of XRD analysis. The unsatisfactory hydrogen storage capacities heretofore observed in cycle tests are shown to be due entirely to the reaction of Na3AlH6 with Al and hydrogen to NaAlH4 (Eq. (1), 2nd hydrogenation step) being incomplete. Using XRD and NMR methods it has been shown that a higher level of rehydrogenation can be achieved by adding an excess of Al powder. © 2002 Elsevier Science B.V. All rights reserved.",The processes occurring in the course of two sequential hydrogen discharging and recharging cycles of Ti-doped sodium alanate were investigated in parallel using XRD analysis and solid-state NMR spectroscopy. Using XRD and NMR methods it has been shown that a higher level of rehydrogenation can be achieved by adding an excess of Al powder.,_
!511,"The activity of the ""Hydrogen Group"" of Padova University, addressed to the study of materials for solid state hydrogen storage, is illustrated. Various Mg-based materials have been considered and are being studied: a) MgH2 and 0.5% mol Nb2O5 mixture ball milled under argon atmosphere; b) Mg-Ni-Fe intermetallic compounds prepared by short time ball milling of ribbons obtained by melt spinning and by long time ball milling of a mixture of MgH2, Ni and Fe powders; c) MgH2 ball milled in argon with Mm-Ni-Al (Mm = La-rich mishmetal) and Zr-Cr-Fe catalyst alloys. All the samples have been structurally characterized by X-ray diffraction (Rietveld refinement) before and after hydrogen absorption/desorption cycling and tested with a Sievert apparatus as regarding their thermodynamic and kinetic properties.","Various Mg-based materials have been considered and are being studied: a) MgH2 and 0.5% mol Nb2O5 mixture ball milled under argon atmosphere; b) Mg-Ni-Fe intermetallic compounds prepared by short time ball milling of ribbons obtained by melt spinning and by long time ball milling of a mixture of MgH2, Ni and Fe powders; c) MgH2 ball milled in argon with Mm-Ni-Al (Mm = La-rich mishmetal) and Zr-Cr-Fe catalyst alloys. All the samples have been structurally characterized by X-ray diffraction (Rietveld refinement) before and after hydrogen absorption/desorption cycling and tested with a Sievert apparatus as regarding their thermodynamic and kinetic properties.",_
!512,"General Motors (GM) Corp. and Sandia National Laboratories have launched a partnership to design and test an advanced method for storing hydrogen based on metal hydrides. GM and Sandia, a National Nuclear Security Administration lab, have embarked on a four year, $10 million program for the project. Researchers also hope to create a tank design that could be adaptable to any type of solid-state hydrogen storage. The project will be conducted in two phases: in phase one, the program will study engineering designs for a sodium alanate storage tank, and in phase two, the promising tank designs will be subjected to rigourous testing, after that fabrication of the storage tanks will be done.","General Motors (GM) Corp. and Sandia National Laboratories have launched a partnership to design and test an advanced method for storing hydrogen based on metal hydrides. The project will be conducted in two phases: in phase one, the program will study engineering designs for a sodium alanate storage tank, and in phase two, the promising tank designs will be subjected to rigourous testing, after that fabrication of the storage tanks will be done.",_
!513,"The concerns about fossil fuel resources depletion and the need of reducing the climate affecting emissions make more and more attractive a future widespread use of hydrogen as energy vector. Hydrogen represents an important option also to store energy in a long term scenario of fluctuating power generation from renewables sources (solar and wind). However, independently from the primary energy sources used for its production in medium and long term (fossil fuel with carbon dioxide sequestration, nuclear, renewables), R&D efforts must be focused henceforward on hydrogen related technologies, like fuel cells and advanced storage systems. Fuel cells, in particular, represent the ideal system to convert the hydrogen chemical energy into electricity with high efficiencies. The CESI experience on a grid connected PEFC system fuelled with hydrogen stored in metal hydrides is outlined in this presentation with emphasis on all the aspects related to subsystem interlacing. A 6,5 Nm3 capacity hydrogen storage was developed at CESI starting from commercial metal hydride powders supplied by LabTech Ltd. The heat transfer during the charge - discharge cycles and the useful hydrogen output were optimised in view of the coupling with a PEFC stack/module operating near ambient pressure. Three Independence 1000 PEFC modules were supplied by ReliOn and carefully characterised at CESI laboratories. This module is a rather open system and a lot of parameters can be acquired at operating conditions including all the cell and cartridges voltages, currents and temperatures. The module responses to an external electric load were investigated both in steady state conditions, by increasing gradually the load, and during steep load changes. The actual hydrogen consumption was measured at different operating conditions and LHV and HHV efficiencies were obtained as a function of the power output. The PEFC modules were connected to the local grid through a 3.3 kW DC-AC converter (inverter) that was supplied by SGS Future based on CESI specifications. The inverter efficiency exceeded 90%. A control system was set up in a LabVIEW™ environment to manage the hydrogen storage charge and discharge cycles and to test the PEFC - inverter system behaviour on different load profiles. Experimental results on the integrated system are presented and discussed. A few critical aspects related to each subsystem and to their interfaces are analysed This work was carried out in the frame of the research on the Italian Electrical System ""Ricerca di Sistema"", Ministerial Decrees of January 26, 2000 and April 17, 2001.","Hydrogen represents an important option also to store energy in a long term scenario of fluctuating power generation from renewables sources (solar and wind). A 6,5 Nm3 capacity hydrogen storage was developed at CESI starting from commercial metal hydride powders supplied by LabTech Ltd.",_
!514,"Although recently there have been many reports on the in-situ structural characterization of hydrogen storage alloys, these studies were all conducted under equilibrium states. In practice, however, hydrogen storage alloys alternate hydrogen absorption and desorption processes ceaselessly. Therefore, in functional situations where hydrogen storage alloys are utilized, their hydrogen absorption properties cannot be evaluated precisely by applying the results of observations made under equilibrium states. We assessed the hydrogen absorption behavior and phase transformation of LaNi 5 during the hydrogen absorption process using our newly developed time-resolved in-situ XRD system for vapor-solid phase reaction. This system, which comprises a chamber for performing in-situ XRD measurements, a Sieverts' component for measuring hydrogenation speed, and a PSPC (position-sensitive proportional counter) X-ray detector, enables sequential XRD measurement in an in-situ atmosphere. Over a period of several minutes, we observed the phase transformation of the master alloy of LaNi 5 into a hydride of LaNi 5H 6 during the hydrogen absorption process and evaluated the process sequentially at intervals of a few seconds. Our results showed that the actual phase transformation during the process of hydrogen storage differs from what had been characterized previously under an equilibrium state. It was also made clear that the lattice volume of the hydride produced remains unchanged between the onset of hydride formation and attainment of the equilibrium state. © 2005 The Japan Institute of Metals.","Although recently there have been many reports on the in-situ structural characterization of hydrogen storage alloys, these studies were all conducted under equilibrium states. We assessed the hydrogen absorption behavior and phase transformation of LaNi 5 during the hydrogen absorption process using our newly developed time-resolved in-situ XRD system for vapor-solid phase reaction.",_
!515,The proceedings contain 49 papers from the conference on Advanced Materials for Energy Conversion II. The topics discussed include: fuel cell materials and components; international hydrogen storage R&D in IEA; solid state and surface phenomena in energy transformation materials; hydrogen storage properties of Li-based complex hydrides; structural and thermodynamic aspects of atlantes for hydrogen storage; advances in hydrogen storage; reaction of hydrogen with an organic hydrogen getter; and in-situ production of nano-structured ceramics by spray solution.,The proceedings contain 49 papers from the conference on Advanced Materials for Energy Conversion II. The topics discussed include: fuel cell materials and components; international hydrogen storage R&D in IEA; solid state and surface phenomena in energy transformation materials; hydrogen storage properties of Li-based complex hydrides; structural and thermodynamic aspects of atlantes for hydrogen storage; advances in hydrogen storage; reaction of hydrogen with an organic hydrogen getter; and in-situ production of nano-structured ceramics by spray solution.,_