Promising Hydrogen Storage Material Research Articles

Effect of different metal element substitution on microstructural and comprehensive hydrogen storage performance of Ti0·9Zr0·1Mn0·95Cr0·7V0.2M0.15 (M = Fe, Co, Ni, Cu, Mo) alloy

Hydrogen is now being used as a renewable clean energy carrier. One of the main issues with the application of hydrogen energy is a shortage of security and efficient hydrogen storage technology. TiMn-based alloys are considered promising hydrogen storage materials, but their comprehensive hydrogen storage properties and cyclic stable performance limit their further practical application. The hydrogen storage properties of alloys can be enhanced by substituting transition metal elements. Therefore, the comprehensive hydrogen storage performance of the Ti0·9Zr0·1Mn0·95Cr0·7V0.2M0.15 (M ​= ​Fe, Co, Ni, Cu, Mo) alloys was systematically investigated according to the Mn element on the B side is partially replaced by variety of transition metal elements. The M ​= ​Ni alloy, which showed the highest hydrogen storage capacity among the group of alloys, was used to explore cycle stability. The plateau pressures of the series alloys decreased in order, Fe ​> ​Co ​> ​Ni ​> ​Cu ​> ​Mo. Aspects of hydrogen absorption kinetics, all of the alloys can reach full hydrogen absorption saturation within 400 ​s at 303 ​K. The Ti0·9Zr0·1Mn0·95Cr0·7V0·2Mo0.15 alloy possessed the fastest hydrogen absorption kinetic rate (t0.9 ​= ​65 ​s) and the smallest hysteresis factor. This suggests that the substitution of Mo elements is effective in improving the hysteresis of the Laves phase alloys. Among the series of alloys, the M ​= ​Ni alloy exhibited the best overall hydrogen storage performance, which hydrogen storage capacity can reach 1.81 ​wt% and 97% of its capacity is kept after 100 cycles.

A Palladium Catalyst Supported on Boron-Doped Porous Carbon for Efficient Dehydrogenation of Formic Acid.

Formic acid has emerged as a highly promising hydrogen storage material, and the development of efficient catalysts to facilitate its dehydrogenation remains imperative. In this study, a novel catalyst consisting of palladium nanoparticles supported on boron-doped porous carbon (Pd/BPC) was successfully synthesized to enable efficient hydrogen production through the dehydrogenation of formic acid. The impacts of the boron doping ratio, doping temperature, and palladium reduction temperature on the catalyst's performance were systemically investigated. The results demonstrated the Pd/BPC catalyst synthesized with a carbon-to-boron ratio of 1:5 by calcination at 900 °C and subsequent reduction at 60 °C exhibited superior formic acid dehydrogenation performance, being 2.9 and 3.8 times greater than that of the Pd/PC catalysts without boron doping and commercial Pd/C, respectively. Additionally, the catalyst showed excellent cycle stability with no significant activity reduction after five consecutive cycles. Experimental and theoretical results reveal that boron doping not only facilitates the homogenous distribution of Pd nanoparticles but also induces a stronger support-metal interaction, thereby reinforcing the catalytic performance. This research is expected to provide valuable insights into the economically viable and efficient production of environmentally friendly hydrogen energy.

Hybrid of bulk NbC and layered Nb4C3 MXene for tailoring the hydrogen storage kinetics and reversibility of Li–Mg–B–H composite: An experimental and theoretical study

The Li-Mg-B-H composite (2LiBH4 + MgH2) is acknowledged as a promising material for hydrogen storage due to its large hydrogen capacity (11.4 wt.%). However, the sluggish kinetics and poor reversibility make it difficult to be practically used. In this work, the hydrogen storage performances of 2LiBH4 + MgH2 have been significantly improved by a hybrid of bulk NbC and layered Nb4C3 MXene (denoted as “Nb–C”). The 2LiBH4 + MgH2 + 6 wt.% Nb–C can release 8.5 wt.% H2 within 30 min at 400 °C and the dehydrogenated composite can absorb 9.3 wt.% H2 within 30 min at 350 °C and 7.5 MPa H2. The reversible dehydrogenation capacity maintains at 8.4 wt.% after 24 cycles, with a capacity retention ratio of 95.4 %. By contrast, the undoped 2LiBH4 + MgH2 suffers from serious capacity degradation, with the capacity decreased dramatically to 3.5 wt.% after 3 cycles. Microstructural studies revealed that the doped composite has uniform particle and elemental distributions and possesses various multiphase interfaces of LiH/MgB2/NbC/Nb4C3, which is beneficial to hydrogen diffusion during the hydrogen uptake and release process. Theoretical studies by first principle calculation presented an extended bond length of the Mg–H and B–H bonds in the 2LiBH4 + MgH2 + NbC system, which may also explain the improved hydrogen storage properties of 2LiBH4 + MgH2 by addition of Nb-C. This work provides new insights into the role of transition metal carbides in regulating the Li–Mg–B–H hydrogen storage materials both experimentally and theoretically.

Research Progress of Hydrogen Storage Materials

Hydrogen energy has become increasingly popular as a clean and renewable source of energy in recent years due to the high levels of carbon pollution worldwide. This essay examines the current research status on various hydrogen storage techniques and materials for hydrogen energy. There are currently three primary hydrogen storage methods: high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage, and solid-state hydrogen storage. The most widely employed method in China is high-pressure gaseous hydrogen storage. It entails compressing hydrogen fuel into a container under high pressure. As a result, high-pressure gaseous hydrogen storage is commonly used for stationary hydrogen storage. Low temperature liquid hydrogen storage involves compressing the hydrogen at first and then cooling it down with liquefaction technology. However, due to the strict requirements for compression and container insulation, its actual performance is often limited. This paper focuses on the study of solid hydrogen storage materials. The physical adsorption materials that are successively introduced include carbon-based hydrogen storage materials, metal-organic frameworks (MOFs), and Covalent organic frameworks (COFs). In the current study, carbon-based hydrogen storage materials show better performance only in low-temperature and high-pressure environments, but MOFs and COFs have great prospects in hydrogen storage. The chemical absorption hydrogen storage materials introduced in this paper are metal alloy hydrogen storage and hydrogenation complexes hydrogen storage, mainly rare earth-based hydrogen storage materials and magnesium-based hydrogen storage materials. Among them, magnesium-based hydrogen storage materials have become one of the most promising hydrogen storage materials due to their low cost and good hydrogen storage performance.

Li Decorated Penta-BCN as a Competitive Reversible Hydrogen Storage Media: A First-Principles Study.

Efficient storage media are crucial for practical applications of hydrogen, which is the most promising clean energy resource. In addition to possessing a highly reversible gravimetric capacity, the stability and superlight mass of potential storage media should not be underestimated. In this study, we exploit the light mass and unique puckered structure of penta-BCNs to design Li-decorated penta-BCNs for hydrogen storage via a series of first-principles calculations. Our results reveal that Li atoms can form stable chemical complexes with the surface of penta-BCNs with an average binding energy of -2.21 eV without causing deformation. Each Li@penta-BCN unit can physically adsorb up to 27H2 molecules, and the highest hydrogen storage capacity can reach 7.44 wt %, with an average adsorption energy of -0.16 eV/H2, surpassing the target value of 5.5 wt % set by the U.S. Department of Energy. Further elaborate analysis of the electronic structure shows the polarization enhancement mechanism, which is caused by charge transfer from Li atoms to the penta-BCN surface. Our results indicate that Li-decorated penta-BCN could be a promising hydrogen storage material for further application and inspire the theoretical or experimental design of novel materials for clean energy.

Phase Diagram Analysis of High-Pressure/High-Temperature Polymorphs of Ammonia Borane.

Ammonia borane (NH3BH3) is a promising hydrogen-storage material because of its high hydrogen density. It is employed as a hydrogen source when synthesizing superconducting polyhydrides under high pressure. Additionally, NH3BH3 is a crystallographically interesting compound that features protonic hydrogen (Hδ+) and hydridic hydrogen (Hδ-), and it forms a dihydrogen bond, which explains its stable existence as a solid. Herein, X-ray diffraction experiments were performed at high pressures (HPs) and high temperatures (HTs) of up to 30 GPa and 300 °C, respectively, to investigate the HP/HT phase diagram of NH3BH3. A new HP/HT phase (HPHT2) was identified above 9 GPa and 150 °C. Crystal-structure analysis using the Rietveld method and stability verification using density functional theory calculations revealed that HPHT2 has a P21/n (Z = 4) structure, similar to that of a previously reported HP/HT phase (HPHT) that appears at a lower pressure. HPHT2 is denser than the HP phases that appear at room temperature (HP1 and HP2) at the same pressure (up to ∼17 GPa). In the phase diagram, the phase-boundary line between HPHT and HP1 is a downward convex curve. These unconventional phenomena in the density and phase boundary can be attributed to the influence of dihydrogen bonding on the crystal structure and phase diagram.

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.

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.

The superiority of Pd2+ in CO2 hydrogenation to formic acid.

The hydrogenation of CO2 to formic acid is an essential subject since formic acid is a promising hydrogen storage material and a valuable commodity chemical. In this study, we report for the first time the hydrogenation of CO2 to formic acid catalyzed by a Pd2+ catalyst, Pd-V/AC-air. The catalyst exhibited extraordinary catalytic activity toward the hydrogenation of CO2 to formic acid. The TON and TOF are up to 4790 and 2825 h-1, respectively, representing the top level among reported heterogeneous Pd catalysts. By combining a study of first-principles density functional theory with experimental results, the superiority of Pd2+ over Pd0 was confirmed. Furthermore, the presence of V modified the electronic state of Pd2+, thus promoting the reaction. This study reports the effect of metal valence and electronic state on the catalytic performance for the first time and provides a new prospect for the design of an efficient heterogeneous catalyst for the hydrogenation of CO2 to formic acid.

Sodium‐Decorated SiB Monolayer for Reversible Hydrogen Storage: High‐Capacity Achieved by Carbon Doping

Based on the first‐principles calculation and grand canonical Monte Carlo (GCMC) simulation, the reversible hydrogen storage of Na‐decorated silicon boron (SiB) and C‐doped SiB monolayers have been investigated. For double side 4Na‐decorated SiB monolayer, each Na atom can adsorb five H2 molecules with the average adsorption energy of −0.18 eV/H2, yielding an H2 gravimetric density of 9.09 wt% and desorption temperature TD of 227 K. To further improve the H2 gravimetric density and desorption temperature, doping effect was employed to enhance the internal electric field between Na atom and SiB substrate. When two Si atoms in the SiB monolayer were replaced by C atoms, the adsorption energy for H2 was significantly improved. The H2 gravimetric density reaches to 10.63 wt% with the average adsorption energy of −0.22 eV/H2. Meanwhile, the desorption temperature TD was raised from 227 to 282 K, reaching the ideal condition near room temperature. In addition, the GCMC simulations further confirm that the H2 gravimetric density can fully meet the latest hydrogen storage target (5.5 wt%) for both Na‐decorated SiB monolayer and Na‐decorated C‐doped SiB monolayer. Our results indicate that both Na‐modified SiB and C‐doped SiB monolayers can be used as promising materials for reversible hydrogen storage.

High-entropy alloys: A review of their performance as promising materials for hydrogen and molten salt storage

Abstract Fossil fuels have been the most employed energy source with a consistent and growing consumption; however, they will be replaced by renewable energy sources (RESs). Massively using this type of energy will require new materials, especially metallic-based materials, because the typical materials have shown poor performance. In particular, hydrogen obtained from RESs has technological concerns like absorption/desorption cycling, kinetics, and cost. Similarly, the solar industry demands highly corrosion-resistant materials at high temperatures. As mentioned above, these could be solved using high-entropy alloys (HEAs). HEAs are barely around 15 years old and have been intensively investigated to be used for wide technological and scientific applications due to their unusual mechanical, physical, and chemical properties. Thus, this study summarizes advances in HEAs as promising materials for hydrogen and energy molten salt storage technologies and discusses the corrosion performance of current HEAs, considering both the microstructure and constituent element effect.

Lithium functionalized heteroborospherene Si4B32 as a promising hydrogen storage material:A density functional theory study

This study investigates the reversible hydrogen storage performance of Lithium (Li)-functionalized heteroborospherene Si4B32 with density functional theory (DFT) methods. The Si4B32 cage can accommodate a maximum of 6Li atoms without clustering, every Li atom can bind up to 4 H2 molecules. The Li6Si4B32 can still keep its integrity after absorbing 24 H2 molecules. The H2 gravimetric density is 8.922 wt% with 0.220 eV/H2 average hydrogen adsorption energy. The desorption temperature of Li6Si4B32.(H2)24 is 281 K, which indicate H2 molecules can be successfully released at near room temperature. We draw a conclusion that Li-decorated Si4B32 is a potential candidate for reversible hydrogen storage.

Rh0.7Ru0.3-MoOx supported on carbon nanotubes boosts hydrogen generation from hydrazine borane at room temperature

Hydrazine borane (HB, N2H4BH3) is gaining attention as a promising chemical hydrogen storage material due to its impressive hydrogen capacity (15.4 wt%) and stability under normal conditions. However, its dehydrogenation properties have remained unsatisfactory despite numerous efforts. In this study, we have successfully developed rhodium-ruthenium nanoparticles modified with MoOx and supported on carbon nanotubes (Rh0.7Ru0.3-MoOx/CNTS) using a facile co-reduction method. Surprisingly, the Rh0.7Ru0.3-MoOx/CNTS catalyst exhibits outstanding performance, surpassing all previously reported activities for HB dehydrogenation. It demonstrates a high turnover frequency (TOF) value of 4412 h−1 at 303 K, 100 % selective conversion of hydrogen, and excellent stability. Through XPS, TEM, BET, and XRD analysis, we have determined that the exceptional performance of Rh0.7Ru0.3-MoOx/CNTS can be attributed to the synergistic effect of CNTS and MoOx on the catalyst's electronic structure, crystal structure, and particle size. These results provide a solid foundation for the potential application of HB in hydrogen fuel cells.

Preparation of Mg-Mg2Ni/C composite and its excellent hydrogen storage properties

Magnesium hydride (MgH2) is a promising hydrogen storage material with high weight and volume hydrogen capacity. However, higher operating temperature and reversible hydrogen capacity decay inhibit its wide application. To address these issues, Mg-Mg2Ni/C was obtained by ball milling magnesium and nickel-Metal Organic Framework (Ni-MOF), and following calcinations. Initial dehydrogenation temperature of the composite is 530 K, 70 K lower than that of MgH2, and the apparent activation energy of the composite is 77.6 ± 2.1 kJ/mol, which is only 50% of MgH2. At 423 K, the hydrogen capacity of the composite is about 6 wt% within 3600 s, and keeps unchanged after ten cycles. The carbon material introduced by Ni-MOF inhibits the agglomeration of Mg, and Mg2Ni/Mg2NiH4 acts as a “hydrogen pump” in de/hydrogenation process. The carbon coating and “hydrogen pump” lead to the improvement of the ab/desorption kinetics and cycling stability. This attempt paves a potential way to achieve high performance Mg-based composite hydrogen storage materials.

Interfacial synergy between Pt3Co nanoparticles and CoO for efficient ammonia borane hydrolysis

Ammonia borane (AB, NH3BH3) with the high H2 content has been regarded as a promising material for chemical hydrogen storage. AB can hydrolyze to release H2 under the catalysis of noble-metal catalysts with high activity, but the high cost of noble-metals and their poor long-term stability prohibit the large-scale applications. Developing more cost-effective and stable catalysts by introducing cheap transition metal elements has been a promising strategy. Herein, we adopted a step-by-step precipitation method to synthesize bimetallic Pt-Co catalysts supported on rutile TiO2, which show significantly improved performance in AB hydrolysis reaction. The optimized 0.9Pt3.5Co/TiO2 catalyst (with the Pt and Co loadings of 0.9 and 3.5 wt%, respectively) exhibits an extremely high H2 generation rate, showing a turnover frequency value of 2163 molH2 molPt-1 min−1 at 298 K, 9 times higher than that of 0.9Pt/TiO2 catalyst and superior to those of most of the reported Pt-based catalysts. Structure characterizations and theoretical calculations reveal that the promoted AB hydrolysis performance arises from the interfacial synergistic effect between the supported Pt3Co alloy and cobalt oxide CoO, which accelerates the B-H bond cleavage and water activation, respectively. The excellent AB hydrolysis performance of the Pt-Co catalysts indicates the great prospects of alloy-oxide interfaces in the field of liquid phase chemical hydrogen storage.

Ni-based catalyst assisted by MnO to boost the hydrogen storage performance of magnesium hydride

Magnesium hydride (MgH2) stands out as a promising solid-state material for high-density hydrogen storage, offering enormous potential for applications in hydrogen transportation and storage. However, the stable thermodynamics and sluggish kinetics of dehydrogenation/hydrogenation of MgH2 impede its practical use in on-board hydrogen storage. In this study, the nanocomposite of nickel/manganese oxide (Ni/MnO) was successfully synthesized through the hydrogenation of nickel-manganese two-dimensional layered double hydroxide (NiMn-LDH) and then introduced into MgH2 by ball milling to form BM-MgH2-Ni/MnO composite. Notably, BM-MgH2-Ni/MnO-10 displayed excellent hydrogen absorption/dehydrogenation properties. For example, its onset hydrogen release temperature was remarkably reduced to 175.6 °C, 84 °C lower than that of BM-MgH2. At a temperature of 250 °C, it could desorb about 6.2 wt% of H2 within 60 min. The fully dehydrogenated product could absorb 5.5 wt% of H2 within 10 min at 150 °C. Moreover, BM-MgH2-Ni/MnO-10 exhibited excellent cycling performance. Throughout the cycling process, the in-situ formation of Mg2Ni/Mg2NiH4 and metal Mn was detected, leading to a synergistic effect that significantly enhanced the hydrogen storage capability of MgH2. This study presents innovative concepts for designing active catalysts to enhance the kinetics of de-/hydrogenation reactions of MgH2.

High-capacity hydrogen storage in lithium decorated penta-BN2: A first-principles study

The development of solid hydrogen storage materials is an important part of the large-scale application of hydrogen energy. The gravimetric density of hydrogen storage materials and modified metal atoms agglomeration are the key research issues in two-dimensional hydrogen storage materials. Based on first-principles calculations, lithium-modified penta-BN2(P-BN2) is developed as a new hydrogen storage material. The geometric and electronic structures of lithium-modified P-BN2 (Li-P-BN2) have been calculated. P-BN2 has strong binding ability to lithium metal atoms, preventing the formation of lithium metal clusters, and the material has a strong stability. Twenty-eight hydrogen molecules can be stably adsorbed by the Li-P-BN2 system, and the theoretical storage gravimetric density of hydrogen is 13.27 wt%. Ab initio molecular dynamics (AIMD) shows that the material has a useable capacity of 8.95 wt% at 300 K. The mean desorption temperature is 437.13 K. The excellent hydrogen adsorption capacity and high gravimetric density of Li-P-BN2 may make it a promising hydrogen storage material.

Catalytic hydrogenation of phenoxide at room temperature using ultrafine Ru–B amorphous alloy

Sodium phenoxide is considered as one of the potentially promising hydrogen storage materials due to its high hydrogen capacity and enhanced thermodynamic properties. However, efficient catalysts are needed to overcome kinetic barriers of the hydrogenation and dehydrogenation processes. In the present work, an ultrafine amorphous Ru–B alloy catalyst was synthesized by a solid-phase ball milling of RuCl3 with NaBH4 and subsequently tested for the hydrogenation of sodium phenoxide in an aqueous solution at room temperature. The conversion of phenoxide is significantly improved by 48.9 % on the Ru3.9B alloy catalyst compared with pristine Ru nanoparticles. Kinetic studies revealed that the hydrogenation of sodium phenoxide is of first-order with respect to H2 pressure and zero-order to the concentration of sodium phenoxide over the Ru3.9B catalyst. Characterizations showed that the electronic structure of Ru is well modulated by B, leading to an electron-rich state of Ru. The highly active catalysis may be due to the fine dispersion, amorphous state, and electron-rich state of Ru in the ultrafine alloy.

Atomistic-geometry inspired structure-composition-property relations of hydrogen sII hydrates

Gas hydrates are crystalline inclusion compounds formed by trapping gas molecules inside water cages at high pressures and low temperatures. Hydrates are promising materials for hydrogen storage, but their potential depends on understanding their mechanical properties. This work integrates density functional theory (DFT) simulations with a geometry-inspired composite material model to explore the bulk moduli of structure II hydrogen hydrates subjected to pressure loads of − 0.2 to 3 GPa, representative of the hydrogen hydrate formation conditions. Our findings reveal that structure II hydrate comprises a bi-continuous composite of small and large cages with nearly equal volume fractions. The bulk modulus increases with rising pressure but decreases with increasing composition. Notably, these results align closely with the ideal laws of mixtures, especially at low pressures and compositions, where cage interactions are minimal. This integrated DFT-laws of mixtures methodology provides a key database for fast estimation of hydrate mechanical properties without costly computations.