Solid-state Hydrogen Storage Materials Research Articles

Mxene-supported NbVH nanoparticles as efficient catalysts for reversible hydrogen storage in magnesium borohydride

Bimetallic niobium vanadium hydride nanoparticles (NbVH NPs) anchored on Ti3C2 were synthesized using a facile ball milling method as an effective catalyst for the dehydrogenation kinetics and reversibility of Mg(BH4)2. It was found that the onset dehydrogenation temperature of the Mg(BH4)2 + 30NbVH NPs@Ti3C2 composite was 105.7 °C and released 9.07 wt% of hydrogen at 330 °C, while undoped Mg(BH4)2 only released 4.2 wt% of H2 from 248 °C to 330 °C. Additionally, the Mg(BH4)2 + 30NbVH NPs@Ti3C2 composite achieved remarkable hydrogen release of over 9.44 wt% at a temperature as low as 230 °C, indicating unexpected dehydrogenation kinetics. In the reversible hydrogen desorption tests, Mg(BH4)2 + 30NbVH NPs@Ti3C2 released 5.98 wt% of H2 in the 2nd cycle at 250 °C and maintained a reversible capacity of 4.35 wt% after 10 cycles, demonstrating a remarkable enhancement in reversibility. The enhancement in the dehydrogenation kinetics of Mg(BH4)2 could be attributed to the greatly reduced activation energies from 343 kJ·mol−1 and 138.3 kJ·mol−1 to 103.7 kJ·mol−1 and 124 kJ·mol−1. Investigations on the evaluation of catalyst and Mg(BH4)2 during reversible hydrogen storage have revealed that NbVH NPs actually acted as a “bidirectional hydrogen pump”, facilitating both the hydrogen release and uptake from Mg(BH4)2. This strategy of multi-component hydrides may show a new way to design effective catalysts for solid-state hydrogen storage materials.

Picturing the Gap Between the Performance and US-DOE's Hydrogen Storage Target: A Data-Driven Model for MgH2 Dehydrogenation.

Developing solid-state hydrogen storage materials requires a comprehensive understanding of the dehydrogenation chemistry of a solid-state hydride. Transition state search and kinetics calculations are essential to understanding and designing high-performance solid-state hydrogen storage materials by filling in the knowledge gap that current experimentscannot measure. However, the ab initio analysis of these processes is expensive and time-consuming. Searching for descriptors to accurately predict the energy barrier is urgently needed, to accelerate the prediction of hydrogen storage material properties and identify the opportunities and challenges. Herein, we develop a data-driven model to describe and predict the dehydrogenation barriers of a typical solid-state hydrogen storage material, MgH2, based on the combination of the crystal Hamilton population orbital of Mg-H bond and the distance between atomic hydrogen.All the parameters in this model can be directly calculated with significantly less computational cost than conventional transition state search, so that the dehydrogenation performance of hydrogen storage materials can be predicted efficiently. Finally, we found that this model leads to excellent agreement with typical experimental measurements reported to date and provides clear design guidelines on how to propel the performance of MgH2 closer to the target set by the United States Department of Energy (US-DOE).

Solid hydrogen storage with palladium-graphene composites: Synthesis, characterization, and mechanistic insights

Efficient and safe hydrogen storage is a pivotal challenge for the advancement of hydrogen energy technologies. To address this, the engineering of high-performance solid-state hydrogen storage materials through the loading of transition metals (TM) on carbon-based solids has gained considerable interest. However, the mechanics for TM such as Palladium that bolster hydrogen storage have not well addressed yet. This work presents hydrogen absorptions with metal Pd nanoparticles loaded on reduced graphene oxide (Pd-rGO), including material preparation, structural characterization, hydrogen storage performance, and quantum chemical mechanistic insights. A simple material synthesis strategy has been explored and Pd-rGO composites are successfully prepared with graphite powder as raw materials by an easy reduction-oxidation process. Then, Pd-rGO composites are characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, Raman, transmission electron microscopy, and nitrogen adsorption-desorption isotherms methods to clarify the detailed structural characteristics of Pd-rGO with different loading amounts. It is found that Pd nanoparticles with an average particle size of 10 nm are uniformly dispersed on the surface of rGO. The materials have high defect severity and increased specific surface areas with Pd loading. The hydrogen adsorption capacity of Pd-rGO can be increased by 64 % compared with that without Pd loading due to the hydrogen spillover effect. In addition, the intensification mechanism of hydrogen storage of Pd-rGO composites is further understood by using density functional theory calculations and surface interaction analysis.

Magnesium-Based Hydrogen Storage Alloys: Advances, Strategies, and Future Outlook for Clean Energy Applications.

Magnesium-based hydrogen storage alloys have attracted significant attention as promising materials for solid-state hydrogen storage due to their high hydrogen storage capacity, abundant reserves, low cost, and reversibility. However, the widespread application of these alloys is hindered by several challenges, including slow hydrogen absorption/desorption kinetics, high thermodynamic stability of magnesium hydride, and limited cycle life. This comprehensive review provides an in-depth overview of the recent advances in magnesium-based hydrogen storage alloys, covering their fundamental properties, synthesis methods, modification strategies, hydrogen storage performance, and potential applications. The review discusses the thermodynamic and kinetic properties of magnesium-based alloys, as well as the effects of alloying, nanostructuring, and surface modification on their hydrogen storage performance. The hydrogen absorption/desorption properties of different magnesium-based alloy systems are compared, and the influence of various modification strategies on these properties is examined. The review also explores the potential applications of magnesium-based hydrogen storage alloys, including mobile and stationary hydrogen storage, rechargeable batteries, and thermal energy storage. Finally, the current challenges and future research directions in this field are discussed, highlighting the need for fundamental understanding of hydrogen storage mechanisms, development of novel alloy compositions, optimization of modification strategies, integration of magnesium-based alloys into hydrogen storage systems, and collaboration between academia and industry.

Solubility of Hydrogen in a WMoTaNbV High-Entropy Alloy.

The WMoTaNbV alloy has shown promise for applications as a solid state hydrogen storage material. It absorbs significant quantities of H directly from the atmosphere, trapping it with high energy. In this work, the dynamics of the absorption of hydrogen isotopes are studied by determining the activation energy for the solubility and the solution enthalpy of H in the WMoTaNbV alloy. The activation energy was studied by heating samples in a H atmosphere at temperatures ranging from 20 °C to 400 °C and comparing the amounts of absorbed H. The solution activation energy EA of H was determined to be EA=0.22±0.02 eV (21.2 ± 1.9 kJ/mol). The performed density functional theory calculations revealed that the neighbouring host atoms strongly influenced the solution enthalpy, leading to a range of theoretical values from -0.40 eV to 0.29 eV (-38.6 kJ/mol to 28.0 kJ/mol).

Improved dehydrogenation performance of LiAlH4 doped with BaMnO3

Due to its high gravimetric capacity of hydrogen (10.5 wt%), LiAlH4 has been regarded as a promising material for solid-state hydrogen storage material for onboard usage. However, high decomposition temperature, poor kinetics and irreversibility retard its application. To counter this problem, various weight percentages of BaMnO3 are introduced into the LiAlH4 system as an additive in this work. As a result, the starting hydrogen release of LiAlH4 was reduced to 109−115 °C and the second desorption temperature occurred at around 134−158 °C, much lower than pure LiAlH4. The isothermal desorption kinetics also proved that faster desorption kinetics can be observed at 90 °C for 80 min. About 2.00−2.60 wt% of H2 could be desorbed by the composite, whereas only <1.00 wt% of H2 was desorbed by undoped LiAlH4. Additionally, adding BaMnO3 reduced the activation energies by 30 kJ/mol for the first stages and 34 kJ/mol for the second stages. Based on the X-ray diffraction result, the active species formed of MnO2 and Ba or Ba−containing materials are believed to be responsible for the noticeable enhancement in the desorption properties of LiAlH4.

Understanding the role of transition metal implantation on 2D graphitic carbon nitride for solid-state hydrogen storage: A first principles study

Modifying 2D materials with transition metals (TMs) proves to be an effective approach for enhancing their properties in hydrogen storage. In this article, the hydrogen interaction and adsorption over transition metal (TM) atoms (V, Mn, Fe, and Cu) implanted graphitic carbon nitride (gC3N4) is investigated using density functional theory (DFT). The stability of the TM atom on the gC3N4 surface is studied using binding energy and charge density calculations. The adsorption of H2 on the gC3N4 and TM-implanted gC3N4 surfaces is studied using adsorption energy, density of states (DOS), projected density of states (PDOS), charge density difference, and Lowdin occupancy analysis. The obtained results show that the Fe-gC3N4 system exhibits the highest adsorption energy of −1.025 eV for one H2. It is found that each Fe atom implanted on gC3N4 can stably adsorb up to 8H2 molecules, and the average adsorption energy of the 8H2 molecules is −0.201 eV/H2. In the context of practical applications for these materials, desorption is investigated employing the van't Hoff equation. Our findings affirm that the Fe-gC3N4 system can serve as an efficient material for solid-state hydrogen storage.

Research Progress and Application Prospects of Solid-State Hydrogen Storage Technology.

Solid-state hydrogen storage technology has emerged as a disruptive solution to the "last mile" challenge in large-scale hydrogen energy applications, garnering significant global research attention. This paper systematically reviews the Chinese research progress in solid-state hydrogen storage material systems, thermodynamic mechanisms, and system integration. It also quantitatively assesses the market potential of solid-state hydrogen storage across four major application scenarios: on-board hydrogen storage, hydrogen refueling stations, backup power supplies, and power grid peak shaving. Furthermore, it analyzes the bottlenecks and challenges in industrialization related to key materials, testing standards, and innovation platforms. While acknowledging that the cost and performance of solid-state hydrogen storage are not yet fully competitive, the paper highlights its unique advantages of high safety, energy density, and potentially lower costs, showing promise in new energy vehicles and distributed energy fields. Breakthroughs in new hydrogen storage materials like magnesium-based and vanadium-based materials, coupled with improved standards, specifications, and innovation mechanisms, are expected to propel solid-state hydrogen storage into a mainstream technology within 10-15 years, with a market scale exceeding USD 14.3 billion. To accelerate the leapfrog development of China's solid-state hydrogen storage industry, increased investment in basic research, focused efforts on key core technologies, and streamlining the industry chain from materials to systems are recommended. This includes addressing challenges in passenger vehicles, commercial vehicles, and hydrogen refueling stations, and building a collaborative innovation ecosystem involving government, industry, academia, research, finance, and intermediary entities to support the achievement of carbon peak and neutrality goals and foster a clean, low-carbon, safe, and efficient modern energy system.

Enhanced reversible hydrogen storage in LiBH4-Mg(BH4)2 composite with V2C-Mxene

Solid-state borohydride was one of the promising solid-state hydrogen storage materials, but the reversibility and kinetics of hydrogen de/absorption in borohydrides still need improvement. In this study, a new strategy of repeated ball milling and melting was first used to produce LiBH4-Mg(BH4)2 nanocomposites (LMBH) effectively loaded on V2C Mxene as the matrix. The LMBH-20V2C composite released 8.1 wt% of hydrogen at 350 °C while un-doped LMBH only released 4.3 wt% under the same conditions. Two-step dehydrogenation with lower activation energies (118.2 and 125.2 kJ/mol) were found in LMBH-V2C composites. More than 5 wt% reversible hydrogen capacity was discovered in LMBH-V2C samples, which was 138 % more than that of un-doped LMBH. The nano-sized LMBH-V2C composite retained unaggregated, and VH2.01 species was formed during cycling as an active “hydrogen pump”. The outstanding hydrogen storage performance of LMBH-V2C composites could be attributed to the combination of nano-sizing and catalysis from V2C Mxene.

Single-Atom Ni Supported on TiO2 for Catalyzing Hydrogen Storage in MgH2.

As an efficient and clean energy carrier, hydrogen is expected to play a key role in future energy systems. However, hydrogen-storage technology must be safe with a high hydrogen-storage density, which is difficult to achieve. MgH2 is a promising solid-state hydrogen-storage material owing to its large hydrogen-storage capacity (7.6 wt %) and excellent reversibility, but its large-scale utilization is restricted by slow hydrogen-desorption kinetics. Although catalysts can improve the hydrogen-storage kinetics of MgH2, they reduce the hydrogen-storage capacity. Single-atom catalysts maximize the atom utilization ratio and the number of interfacial sites to boost the catalytic activity, while easy aggregation at high temperatures limits further application. Herein, we designed a single-atom Ni-loaded TiO2 catalyst with superior thermal stability and catalytic activity. The optimized 15wt%-Ni0.034@TiO2 catalyst reduced the onset dehydrogenation temperature of MgH2 to 200 °C. At 300 °C, the H2 released and absorbed 4.6 wt % within 5 min and 6.53 wt % within 10 s, respectively. The apparent activation energies of MgH2 dehydrogenation and hydrogenation were reduced to 64.35 and 35.17 kJ/mol of H2, respectively. Even after 100 cycles of hydrogenation and dehydrogenation, there was still a capacity retention rate of 97.26%. The superior catalytic effect is attributed to the highly synergistic catalytic activity of single-atom Ni, numerous oxygen vacancies, and multivalent Tix+ in the TiO2 support, in which the single-atom Ni plays the dominant role, accelerating electron transfer between Mg2+ and H- and weakening the Mg-H bonds. This work paves the way for superior hydrogen-storage materials for practical unitization and also extends the application of single-atom catalysis in high-temperature solid-state reactions.

Introducing Ni-N-C ternary nanocomposite as an active material to enhance the hydrogen storage properties of MgH2

The use of Mg-based materials as solid-state hydrogen storage materials can provide a viable solution to the bottleneck hindering the development of hydrogen energy. However, it is necessary to address their excessively stable thermodynamic properties and sluggish kinetic performances. In this study, we prepared a Ni-N-C ternary nanocomposite (designated as Ni@NC) catalyst using Ni-based metal-organic frameworks (Ni-MOFs) as a precursor for catalytic MgH2 hydrogen storage properties. The Ni@NC catalyst exhibited excellent promotion effects on the hydrogen absorption and desorption kinetics and the cycling stability of the Mg-based materials. Notably, the composite exhibited room-temperature hydrogen absorption initiation and an onset dehydrogenation temperature of 188 °C, with complete hydrogenation achieved after holding at 100 °C for 60 min. After undergoing 100 cycles of absorption/dehydrogenation, the capacity retention rate was 99.5 %. The differential scanning calorimetry (DSC) test results indicated that the re-hydrogenated MgH2-Ni@NC composites consist of Mg2NiH4 and MgH2, with corresponding dehydrogenation activation energies of 75.2 and 82.9 kJ mol−1 respectively. The mechanism analysis revealed that Ni@NC was uniformly distributed on the MgH2 surface. During dehydrogenation/rehydrogenation, Mg2NiH4/Mg2Ni “hydrogen pumping” by Ni and MgH2/Mg occurred in situ, the presence of N-C effectively inhibited the expansion of MgH2/Mg, and the enhanced charge transfer effect was facilitated by N in the Ni@NC composite, synergistically enhancing the kinetic performance and cycling stability of MgH2.

Hydrogen Storage Capacity of Lead-Free Perovskite NaMTH3 (MT=Sc, Ti, V): A DFT Study

Hydrogen is a promising clean energy carrier, but its storage is challenging. In this study, we investigate the potential of NaMTH3 (MT=Sc, Ti, V) hydride perovskite as solid-state hydrogen storage material. Using density functional theory (DFT), we comprehensively analyze their structural, hydrogen storage, phonon, electronic, elastic, and thermodynamic properties. Mechanical stability is assessed through calculation of lattice parameters, bulk and shear moduli, Poisson’s ratio, and Young’s modulus based on elastic constants. All three hydrides were found to be stable mechanically. Furthermore, the anisotropy factor was also investigated. Results show that the investigated hydrides are brittle and metallic. Their metallic character is due to the significant interplay between phonons and electrons. We also investigated their enthalpy, entropy, free energy, Debye temperatures, and specific heat capacities to investigate thermal stability.

Electrolytic Hydrogen Release from Hydrogen Boride Sheets.

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 -0.445V 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.

Experimentally validated design principles of heteroatom-doped-graphene-supported calcium single-atom materials for non-dissociative chemisorption solid-state hydrogen storage

Non-dissociative chemisorption solid-state storage of hydrogen molecules in host materials is promising to achieve both high hydrogen capacity and uptake rate, but there is the lack of non-dissociative hydrogen storage theories that can guide the rational design of the materials. Herein, we establish generalized design principle to design such materials via the first-principles calculations, theoretical analysis and focused experimental verifications of a series of heteroatom-doped-graphene-supported Ca single-atom carbon nanomaterials as efficient non-dissociative solid-state hydrogen storage materials. An intrinsic descriptor has been proposed to correlate the inherent properties of dopants with the hydrogen storage capability of the carbon-based host materials. The generalized design principle and the intrinsic descriptor have the predictive ability to screen out the best dual-doped-graphene-supported Ca single-atom hydrogen storage materials. The dual-doped materials have much higher hydrogen storage capability than the sole-doped ones, and exceed the current best carbon-based hydrogen storage materials.

Synergistic effect of Pd single atoms and clusters on the de/re-hydrogenation performance of MgH2

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.

Phonon transport characteristics of α, β, and γ crystalline phases of magnesium hydride from first-principles-based anharmonic lattice dynamics

The superior gravimetric and volumetric hydrogen capacities of magnesium hydride (MgH2) make it a promising candidate material for solid-state hydrogen storage. However, the slow kinetics of hydrogen atoms and the high thermodynamic stability of MgH2 hinder its practical application. To address the challenging issue of adsorption–desorption in MgH2, structural engineering involving nanostructuring has been used to improve the hydrogen-storage characteristics of this material. However, although structural engineering and thermal management significantly influence material properties, no microscopic understanding of the heat conduction property of pristine MgH2 exists. Further advances in the thermal engineering of MgH2-based hydrogen-storage materials require a better understanding of heat conduction in pristine MgH2, particularly knowledge of how the crystalline phases of MgH2 depend on the hydrogen concentration and external pressure. This study uses first-principles-based anharmonic lattice dynamics to quantitatively investigate the intrinsic thermal conductivity of heat-carrying phonons in pristine MgH2 with three different crystalline phases α, β, and γ. The results show that the thermal conductivity of MgH2 depends on the crystalline phase and that the magnitude of the thermal conductivity increases in the order α, γ, and β. In contrast, the volumetric heat capacity and mean squared displacements of the constituent atoms are similar for all three phases. Furthermore, as observed for the pressure dependence of phonon transport, increasing the pressure reduces the thermal conductivity of all phases. However, for the γ and β phases, these reductions are relatively moderate because of the competing effects of group velocity and relaxation time, which have opposite dependencies on pressure. Finally, modal analysis indicates that the spectral features of the phonon transport properties under an applied external pressure are comparable to those at atmospheric pressure. These results should help tailor the heat dissipation of MgH2 while maintaining its hydrogen adsorption–desorption performance through structural engineering.

Mechanism of hydrogenation and dehydrogenation in Mg/Cu9Al4 @Mg and MgH2/Cu9Al4 @MgH2: A DFT and experimental investigation

The Cu9Al4 intermetallic has been found to enhance the hydrogenation and dehydrogenation capabilities of Mg. However, its impact on kinetics is unclear. In the present work, the hydrogenated and dehydrogenated mechanism were investigated by experimental and theoretical methods, including Density Functional Theory (DFT) and ab initio molecular dynamic (AIMD) simulations. Experimental results show that the addition of Cu9Al4 IMC can promote the hydrogenation and dehydrogenation kinetics of Mg, which the dehydrogenation rate of Cu9Al4 @MgH2 is 3 times that of MgH2. AIMD simulations illustrate that the electron properties of Cu9Al4 @Mg and Cu9Al4 @MgH2 are different from that of pure Mg and MgH2, which lead to the change of hydrogenated and dehydrogenated mechanism in Mg/Cu9Al4 @Mg and MgH2/Cu9Al4 @MgH2. Moreover, the diffusion coefficient of H atoms in Cu9Al4 @MgH2 is 4 times that in MgH2. The addition of Cu9Al4 IMC decreases the particle size of Cu9Al4 @Mg during ball milling and induces lattice distortion of Cu9Al4 @MgH2 during the dehydrogenation process. These changes may contribute to the enhancement of the dehydrogenation rate in Cu9Al4 @MgH2. This work complements the mechanism of IMC for improving the performance of hydrogen storage materials and provides a theoretical basis for the development of next-generation solid-state hydrogen storage materials.

Computational evaluation of comprehensive properties of MgX3H8 (X = Sc, Ti and Zr) as effective solid state hydrogen storage materials

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.

Solvent- and catalyst-free reduction of CO2 with ammonia borane

The catalyst-free CO2 reduction with ammonia borane in the solid state is reported. Close to 40 mmol of CO2 per gram of ammonia borane can be reduced at 0.5 MPa and 60 °C to formamide in high yield, achieving a highly atom-economical process.

Improving the desorption properties of LiAlH4 by the addition of Ni0.6Zn0.4O

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.