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In the pursuit of sustainable energy solutions, the development of materials with efficient hydrogen and methane storage capacities is imperative, particularly for advancing hydrogen-powered vehicles. Metal–organic frameworks (MOFs) have emerged as promising candidates to meet the stringent targets set by the Department of Energy for both hydrogen and methane storage. This study employs Grand Canonical Monte Carlo simulations to investigate the usable hydrogen and methane gravimetric and volumetric storage capacities of the recently synthesized SIGSUA. A comparative analysis encompasses the selected MOFs with similar metal compositions, those with comparable density and average pore radius, and classical benchmarks, such as IRMOF-15 and IRMOF-20, all evaluated at room temperature and moderate pressures ranging from 25 to 35 MPa. The results reveal that SIGSUA demonstrates noteworthy gravimetric and volumetric storage capacities for both hydrogen and methane, rivaling or surpassing those of the selected MOFs for analysis. These findings underscore the potential of SIGSUA in advancing clean energy storage technologies. [ABSTRACT FROM AUTHOR]

The reversible hydrogenation/dehydrogenation of aromatic molecules, known as liquid organic hydrogen carriers (LOHCs), is considered an attractive option for the safe storage and release of elemental hydrogen. The LOHC systems based on the alkoxy-naphthalene/alkoxy-decalin studied in this work can become potentially attractive from the point of view of the thermodynamic conditions of the reversible hydrogenation/dehydrogenation processes. This work reports the results of a complex experimental investigation of the thermochemical properties of the reactants of the LOHC systems. The enthalpies of formation were measured using high-precision combustion calorimetry, the enthalpies of vaporization and sublimation were derived from the vapor pressure–temperature dependencies measured using the transpiration method, and the melting temperatures and enthalpies of fusion were measured using the differential scanning calorimetry method. The liquid-phase enthalpies of formation of methoxy- and ethoxy-substituted naphthalenes and methoxy- and ethoxy-substituted decalins were derived and used for the thermodynamic analysis of hydrogenation/dehydrogenation reactions and transferhydrogenation reactions. [ABSTRACT FROM AUTHOR]

There is growing interest in the use of hydrogen as a transportation fuel but the environmental benefits of using hydrogen depend critically on how it is produced and distributed. Leading alternatives to using fossil natural gas to make hydrogen through the conventional method of steam methane reforming include using electrolyzers to split water into hydrogen and oxygen, and the use of biogas as an alternative feedstock to fossil natural gas. This report examines the latest carbon intensity (CI) estimates for these and various other hydrogen production processes, adding important nuances to the general “colors of hydrogen” scheme that has been used in recent years. CI values for hydrogen production can vary widely both within and across hydrogen production pathways. The lowest CI pathways use biomass or biogas as a feedstock, and solar or wind power. The report also analyses jobs creation from new hydrogen production facilities and shows that these benefits can be significant for large-scale facilities based on either future biomass/biogas-to-hydrogen or solar-hydrogen production technologies. Recommendations include setting stricter goals for the state’s Low Carbon Fuel Standard (LCFS) program to continue to reduce the carbon footprint of California’s transportation fuels.

Nanoscale magnesium clusters are important potential hydrogen storage materials, and density functional theory (DFT) is mainly used for their theoretical investigation. The results of the coupled-cluster theory at the singles and doubles level with a perturbative treatment of triples [CCSD(T)] were employed previously to choose proper exchange–correlation (XC) functionals in DFT calculations for magnesium clusters, but it is too expensive to be applied to Mgn with n > 7. The diffusion Monte Carlo (DMC) method is employed in this work to study magnesium clusters up to nanosize. The error of atomization energies with DMC using single-determinant-Jastrow (SDJ) trial wavefunctions has been shown to be somewhat larger than that of CCSD(T) for many molecules. However, cohesive energies with DMC using SDJ for Mgn with n ≤ 7 are in excellent agreement with those of CCSD(T) using the aug-cc-pVQZ basis set, with a difference of less than 1 kcal/mol. DMC results are employed to investigate the performance of different XC functionals on magnesium clusters. Our results indicate that the PBE0 functional is the best XC functional for determining the lowest-energy isomer when compared with DMC results, while the RPBE functional is the best XC functional for calculating cohesive energies per atom of these magnesium clusters with a mean absolute error of 0.5 kcal/mol. These XC functionals are expected to provide reasonable results for even larger magnesium clusters. [ABSTRACT FROM AUTHOR]

Hydrogen (H2) combustion and solid oxide fuel cells (SOFCs) can potentially reduce aviation-produced greenhouse gas emissions compared to kerosene propulsion. This paper outlines a methodology for evaluating performance and emission tradeoffs when retrofitting conventional kerosene-powered aircraft with lower-emissionH2 combustion and SOFC hybrid alternatives. The proposed framework presents a constant-range approach for designing liquid hydrogen fuel tanks, considering insulation, sizing, center of gravity, and power constraints. A lifecycle assessment evaluates greenhouse gas emissions and contrail formation effects for carbon footprint mitigation, while a cost analysis examines retrofit implementation consequences. A Cessna Citation 560XLS+ case study shows a 5% mass decrease for H2 combustion and a 0.4% mass decrease for the SOFC hybrid, at the tradeoff of removing three passengers. The lifecycle analysis of green hydrogen in aviation reveals a significant reduction in CO2 emissions for H2 combustion and SOFC systems, except for natural-gas-produced H2 combustion, when compared to Jet-A fuel. However, this environmental benefit is contrasted by an increase in fuel cost per passenger-km for green H2 combustion and a rise for natural-gas-produced H2 SOFC compared to kerosene. The results suggest that retrofitting aircraft with alternative fuels could lower carbon emissions, noting the economic and passenger capacity tradeoffs.

Motivated by the recent experimental study on hydrogen storage in MXene multilayers [Liu et al., Nat. Nanotechnol. 16, 331 (2021)], for the first time we propose a workflow to computationally screen 23 857 compounds of MXene to explore the general relation between the activated H2 bond length and adsorption distance. By using density functional theory we generate a dataset to investigate the adsorption geometries of hydrogen on MXenes, based on which we train physics-informed atomistic line graph neural networks (ALIGNNs) to predict adsorption parameters. To fit the results, we further derived a formula that quantitatively reproduces the dependence of H2 bond length on the adsorption distance from MXenes within the framework of Pauling's resonating valence bond theory, revealing the impact of transition metal's ligancy and valence on activating dihydrogen in H2 storage. [ABSTRACT FROM AUTHOR]

Creating the porous Zinc-Zeolitic Imidazolate Framework (Zn-ZIF) using a solvothermal technique addresses the need for advanced materials with distinctive properties and cost-effectiveness in modern applications. The PXRD, SEM, UV-DRS, TEM, and TGA/DTG are used to characterize different concentrations of Zn-ZIF. Zn-ZIF's crystalline structure and phase purity have been verified by PXRD. Using diffuse reflectance spectra, the Kubelka-Monk function determined the band gaps of the Zn-ZIF samples, and scanning electron microscopy revealed a more porous structure. At 77 K and 1 bar, the Zn-ZIF solution with a 2:1 ratio had the highest hydrogen storage capacity (1.71 wt%). The electrochemical behavior of several Zn-ZIF electrodes in a 6 M KOH electrolyte was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments. The Zn-ZIF electrode with a 2:1 ratio exhibits a low charge transfer resistance and a high proton diffusion coefficient (D) of 1.687 × 10−4 cm2 s−1. The characteristics of the 2:1 synthesized Zn-ZIF electrode as a supercapacitor were investigated. Our analysis of the generated Zn-ZIF material's specific capacitance values after 2000 cycles revealed an impressive retention rate of nearly 89 %, with values of 296.6 Fg-1. In addition, we examined the photocatalytic activities of the as-synthesized material by exposing it to ultraviolet light and seeing how it degraded organic dyes such as Cango-Red (CR) dye. With a photocatalytic efficacy of 95.06 % for CR dye, Zn-ZIF (2:1 ratio) is the most effective. These findings should provide new knowledge for researchers interested in developing novel Zn-ZIF materials for photocatalytic, energy storage, and hydrogen storage applications. [ABSTRACT FROM AUTHOR]

The hydrogen storage capabilities of the metal–organic framework (MOF) CALF-20 are examined experimentally with both cryogenic and near-ambient temperatures. This framework has a pore size that is nearly ideal for cryogenic hydrogen storage. Density functional theory (DFT) studies provide insights into the hydrogen binding sites within CALF-20. [ABSTRACT FROM AUTHOR]

Underground hydrogen storage (UHS) promises great storing potential for energy produced from renewables. To make UHS a feasible and safe process, fundamental research investigating the integrity of the cement sheath applied in boreholes against hydrogen exposure is essential. In this study, hydrothermal autoclave experiments are conducted to evaluate hydrogen induced changes in the mineralogical phase composition and the microstructure of a class G cement. X-ray diffraction and scanning electron microscopy combined with nitrogen adsorption/desorption experiments are carried out. Only minor mineralogical changes are observed such as the decomposition of monosulphate and the formation of ettringite. Nitrogen adsorption/desorption experiments reveal comparable pore size distributions with minor differences in porosity and surface area. The findings of this study suggest that hydrogen does not substantially affect the phase composition and microstructure of the investigated low permeable class G cement sheath emphasizing the relatively unreactive nature of downhole cements of this type against hydrogen. [Display omitted] • Hydrogen does not change the major phase composition of class G cement. • Microstructure and pore size distribution are not altered. • Hydrogen and brine presence favour ettringite formation at low T. • Low reactivity of class G cement with hydrogen. [ABSTRACT FROM AUTHOR]

This study is a practical exploration of the application of machine learning for the mechanical analysis of filament-wound thin-composite hydrogen storage tanks under internal pressure. Our innovative approach seamlessly integrates classical laminate theory, comprehensive parametric analysis, and machine learning to advance the state-of-the-art in composite tank design. This versatile framework holds promise for addressing challenges in other structurally complex systems. A comprehensive parametric study was then conducted to explore the influence of key design parameters, such as internal pressure, tank radius, order of layer, and layer orientation. Pearson's correlation analysis was used to determine the parameters that had the most significant impact on the mechanical behavior of the tank. In addition, five machine learning models, namely, Extreme Gradient Boosting, Adaptive Boosting, Artificial Neural Network, Support Vector Machine, and Random Forest, were examined to determine their predictive capability for the mechanical performance of these composite tanks. Key findings demonstrate XGBoost's superior predictive capabilities, achieving a remarkable 99% accuracy in predicting stress in the x-direction compared to Random Forest's 96%. XGBoost also outperformed Random Forest in terms of Mean Absolute Error (MAE) and Mean Absolute Percentage Error (MAPE) with values of 26 and 0.02, respectively, versus 207 and 0.16. These results underscore XGBoost's potential to revolutionize hydrogen storage tank design. The development of a user-friendly GUI application further enhances the practicality of this research, allowing engineers and composite designers to efficiently simulate the mechanical behavior of these tanks in real time by adjusting the cursors for variables such as the pressure, radius, layer order, and layer orientation. This tool, with its intuitive interface and elimination of manual calculations, promises significant enhancements in the design process, providing a platform for the rapid assessment and optimization of tank architectures, thereby improving the efficiency and reliability of the design process. [Display omitted] • Developed a hybrid ML approach with laminate theory for accurate composite hydrogen tank predictions. • Key design parameters affecting tank performance were identified through advanced statistical analysis. • Achieved 99% accuracy in stress prediction with XGBoost, outperforming traditional methods. • Enhanced the design process with a user-friendly GUI for real-time tank optimization, significantly reducing development time. [ABSTRACT FROM AUTHOR]

Ti-doped [1,1,1,1] paracyclophane(PCP) and its derivatives have been designed by substituting heteroatoms boron and nitrogen and studied their hydrogen storage properties using density functional theory. Heteroatom substitution is important for stronger Ti-binding whereas Ti-doping for light weight, almost empty d- orbital and its stronger interaction with H 2 molecules. Six configurations are obtained: PB1,PB2(boron substitution), PN1,PN2 (nitrogen substitution) and PBN1,PBN2(boron and nitrogen co-substitution). Stability of all Ti-doped structures has been confirmed using cohesive and formation energy. PCP, PB1, PB2, PN1, PN2, PNB1 and PNB2 show gravimetric hydrogen uptake capacity(adsorption energy) as 5.52(0.67),6.90(0.5),6.90(0.53),5.37(0.6),5.37(0.61), 5.48(0.7) and 5.48(0.74 eV) wt% respectively. Ti-doped boron substituted structures show required H 2 uptake capacity, suitable adsorption energy, thermodynamically favorable H 2 adsorption at ambient conditions, moderate desorption temperature, structural and thermodynamic stability, thus more suitable for hydrogen storage than nitrogen substituted and boron and nitrogen co-substituted structures. Ti-doped boron substituted PCP is a promising reversible hydrogen storage candidate. [Display omitted] • Ti-doped B/N or B and N substituted paracyclophane(PCP) is considered for H 2 uptake. • B-substituted Ti-PCP is more suitable for H 2 storage compared to other structures. • Ti atom strongly bind with B-substituted Ti-PCP compared to other structures. • One extra H 2 gets adsorbed on each Ti on B-substituted Ti-PCP than Ti-PCP [ABSTRACT FROM AUTHOR]

HPSB (Hydrolysis Product of Sodium Borohydride) hydrogen storage material is a kind of porous lamellar structural material developed by our research group. Due to the special structure of this material, it can absorb hydrogen at room temperature, hydrogen absorption pressure is 2–4 MPa, and hydrogen absorption time is 2–5 min. The main preparation method used in the experiment is hydrolysis. The main raw material is sodium borohydride, and the reaction temperature is 30 °C. In this experiment, in order to improve the hydrogen storage performance of HPSB hydrogen storage material, Co–B and Sm 2 O 3 were introduced as catalysts during the preparation of HPSB. The results show that the amount of Sm 2 O 3 and the ratio of Sm 2 O 3 to Co–B have obvious influence on the hydrogen storage performance of HPSB. In addition, according to the results of SEM analysis, the amount of Sm 2 O 3 and the ratio of Sm 2 O 3 to Co–B also have obvious effects on the microstructure of HPSB hydrogen storage materials. The sample with a doping amount of 4 wt% and a ratio of Sm 2 O 3 to Co–B of 4:6 can release 2.17 wt% H 2. • The catalyst Co–B/Sm 2 O 3 can improve the hydrogen storage performance of HPSB. • Co–B/Sm 2 O 3 doping 4 wt% and ratio 4:6 shows the best dehydrogenation performance. • The maximum total dehydrogenation amount of the Co–B/Sm 2 O 3 doped sample is 2.17 wt%. [ABSTRACT FROM AUTHOR]

Hydrogen (H 2)-based steel making is expected to become a major driver of intercontinental low-carbon H 2 imports. Eight H 2 supply scenarios based on either local H 2 production at major steel producing locations (Germany/Japan), or liquid H 2 carrier (dibenzyltoluene/perhydrodibenzyltiluene, DBT/PDBT) import from the United Arab Emirates, and their integration with H 2 direct reduced iron (H-DRI) and electric arc furnace (EAF) processes, are investigated using process modeling. Solar energy-based PDBT import using surplus heat for dehydrogenation is the most cost-competitive H 2 import scenario in Germany's case (levelized steel production cost, ∼685 $/tLS, with carbon emissions, ∼237 kgCO 2 /tLS). In Japan's case this scenario is the most economically favorable of all scenarios (∼736 $/tLS), with emissions (∼350 kgCO 2 /tLS) comparable to natural gas-DRI-EAF with 50% carbon capture. Steam methane reforming with carbon capture-based PDBT import is neither environmentally nor economically viable. PDBT-based H-DRI-EAF production cost is sensitive to electricity, H 2 production, dehydrogenation energy, and carbon costs. • LOHC import from UAE to Germany/Japan for steel making is expected to be feasible. • Integrated LOHC dehydrogenation and HDRI-EAF steel making processes are proposed. • Renewable LOHC steel making emissions are 75% lower than for conventional DRI-EAF. • Renewable LOHC steel can be produced within medium-bound projected H-DRI-EAF cost. • SMR-CCS LOHC is neither environmentally nor economically competitive. [ABSTRACT FROM AUTHOR]

In this paper, it is experimentally demonstrated that the La–Ni catalyst contributes to the hydrogen storage performance of MgH 2. Firstly, La–Ni (La: Ni = 1: 5.7) catalysts are prepared by CaH 2 reduction method, and then MgH 2 + x wt.% La–Ni (x = 0, 3, 5, 7) composite alloys were prepared by ball milling method. The present work focuses on the structural and hydrogen ab/desorption properties of the composite alloys, and analysis the modulatory effect and influence mechanism of different La–Ni catalyst additions on the hydrogen storage properties of MgH 2. The findings show that the composite alloys have the same diffraction peaks and that the main phase of the composite alloys is the MgH 2 phase, with the addition of the LaNi 5 phase, the Mg 2 Ni phase and a small amount of Mg phase. The mutual reversible transformations of LaH 3 and Mg 2 Ni and Mg 2 NiH 4 play a catalytic role in the hydrogen ab/desorption process. Moreover, the addition of La–Ni catalyst plays a dramatic improvement effect on the kinetic performance of MgH 2 ab/desorption. When the addition of La–Ni catalyst is 5 wt.%, the composite alloy exhibits the most excellent hydrogen uptake and release kinetics. The MgH 2 +5 wt.% La–Ni composite alloy absorbs 4.2 wt.% H 2 within 2 min at 473 K and releases 3.43 wt.% H 2 within 150 min at 503 K. Fitting the hydrogen release activation energy of the composite alloys shows that the hydrogen release activation energy of the composite alloys decreases first and then increases, and there is a minimum hydrogen release activation energy of 101.81 kJ/mol H 2 when the addition amount x = 5 wt.%. The mechanism of catalytic MgH 2 absorption/excretion catalyzed by La–Ni catalysts and hydrogen release curve of MgH 2 + x wt.% La–Ni (x = 0, 3, 5, 7) at 613 K. [Display omitted] • Successful preparation of La–Ni catalyst by reduction method. • La–Ni catalysts reduces the hydrogen uptake/release temperature of MgH 2. • La–Ni catalyst reduces the activation energy of MgH 2 for hydrogen release. • In situ generated LaH 3 phase and Mg 2 Ni phase synergistically catalyze the MgH 2. [ABSTRACT FROM AUTHOR]

Utilizing cutting-edge computational screening methods, this study explores the hydrogen storage capacity of two complex metal hydrides, Cs 2 CaH 4 and Rb 2 CaH 4. We perform a thorough analysis of their structural, electrical, optical, and hydrogen storage properties using density functional theory (DFT). Within the I 4/ mmm space group, both compounds display stable tetragonal crystal structures, and their thermodynamic stability is confirmed by their formation energies. Notably, compared to Rb 2 CaH 4 , Cs 2 CaH 4 is more stable. With band gaps of 2.99 eV for Cs 2 CaH 4 and 3.28 eV for Rb 2 CaH 4 , the electronic properties show insulating behavior, which is beneficial for reducing electronic interference during hydrogen absorption and desorption. A comparative research reveals that the potential gravimetric hydrogen storage capacities of Cs 2 CaH 4 (1.28%) and Rb 2 CaH 4 (1.86%) are comparable to, albeit marginally less than, those of materials that are frequently explored, such as lithium borohydride. With their individual absorption and reflectivity peaks, the optical characteristics offer more information about how they interact with electromagnetic radiation, information that may be useful for improving their performance in real-world applications. Our results imply that Cs 2 CaH 4 and Rb 2 CaH 4 have considerable potential for use in practical hydrogen storage systems, especially in situations where stability and minimal electronic interference are essential. Subsequent research endeavors may concentrate on enhancing the hydrogen storage capacity of these materials, so rendering their incorporation into existing hydrogen storage methods more feasible. • Comprehensive computational screening of Rb 2 CaH 4 and Cs 2 CaH 4 for hydrogen storage applications. • Detailed analysis of structural, electronic, and optical properties using DFT calculations. • Rb 2 CaH 4 and Cs 2 CaH 4 exhibit high thermodynamic stability and suitable insulating properties. • Promising gravimetric hydrogen storage capacities: 1.86% for Rb 2 CaH 4 and 1.28% for Cs 2 CaH 4. [ABSTRACT FROM AUTHOR]

We investigate ammonia decomposition under temperature pulsing toward enhancing H 2 production. We observed up to a 10x increase in conversion with rapid pulsing under certain conditions. Our kinetic analysis identified the association of N 2 as the rate-limiting step, showing significant rate enhancement by pulsing at high frequencies and temperature amplitudes. These findings highlight that rapid heat addition and removal, through joule heating, can boost performance and assist with decarbonization. [Display omitted] • Rapid pulse heating of ammonia decomposition can increase ∼10x the ammonia conversion compared to conventional heating. • Pulse heating enhances the N 2 dissociation step by promoting NH 2 ∗ and reducing the N∗ coverage. • Low average temperatures and high frequency-temperature amplitude maximize performance enhancement. [ABSTRACT FROM AUTHOR]

Understanding the properties of solid-state materials at the nanoscale is a crucial scientific endeavor in the pursuit of a sustainable energy future. Since magnesium hydride is the most practical material for hydrogen storage, research is still ongoing to reduce the enthalpy for dehydrogenation. In this computational theory, we systematically investigated the enthalpy of dehydrogenation of Mg n H m nanoclusters of different sizes (0.5–2.8 nm) through density functional theory (DFT) and ab-initio molecular dynamic (AIMD) simulations. Our results revealed that increasing the Mg n H m nanocluster size can remarkably improve the formation energy compared to the MgH 2 -bulk stabilization; the formation energy shifted from −65.12 kJ/mol for (0.5 nm)-Mg n H m nanocluster to −51.37 kJ/mol for (2.8 nm)-Mg n H m nanocluster. As compared to bulk phase, the lower stability of the nanoclusters indicates that it is much easier to desorb hydrogen from the surface. According to the effects of compressive/tensile strains, (2.8 nm)-Mg n H m nanocluster does not improve the dehydrogenation temperature in the desired direction. Unlike metal doping, 9.10%@Ni and 10.14%@V-doped (2.8 nm)-Mg n H m nanocluster exhibit formation energies of −47.27 and −46.34 kJ/mol with calculated desorption temperatures of 362.89 and 355.75 K, respectively, which ensures the room temperature applicability of this hydrogen storage material. [Display omitted] • The size effect of Mg n H m nanoclusters on thermodynamic properties through ab initio density functional calculations. • The compressive/tensile strains on the dehydrogenation properties of (2.8 nm)-Mg n H m are briefly reviewed. • Discovering Ni/V-doped system efficiency, reducing dehydrogenation temperature, boosting hydrogen storage performance. [ABSTRACT FROM AUTHOR]

Liquid hydrogen plays a critical role in large-scale hydrogen storage and long-distance transport. The primary cost associated with liquid hydrogen supply is attributed to the liquefaction consumption. The hydrogen turbo-expander, a pivotal component in industrial hydrogen liquefaction plants, is instrumental in determining liquefaction costs. Improving the efficiency of the expander offers a significant opportunity for cost reduction. This paper commences by validating the loss model employed to assess the hydrogen turbo-expander using numerical simulation results. Subsequently, a regional division model is introduced for the expander impeller passage to identify the locations of various losses. Under diverse operational conditions, the boundaries of regions are determined through a comparison between the loss model and numerical simulation. Finally, an examination of losses in the hydrogen turbo-expander is conducted using Computational Fluid Dynamics (CFD) results under varying operating conditions, yielding the following insights. With an increase in the expansion ratio of the hydrogen turbo-expander, the isentropic efficiency initially rises and then declines. Among the various losses observed under variable working conditions, incidence loss emerges as the most critical factor. When the expansion ratio is small, a negative attack angle forms at the impeller inlet, causing chaotic flow within the channel and an increase in passage loss. • Correlations in loss model are validated for hydrogen turbo-expanders. • The proposed regional division model enables a quantitative loss analysis. • Efficiency decays more severely with the expansion ratio lower than design value. • Incidence loss is the primary driver for efficiency decline far from design condition. [ABSTRACT FROM AUTHOR]

Perovskite oxides LaFeO 3 has been considered as one of the most promising candidates as the negative electrode material of Ni/MH batteries, due to its advantages such as low cost, outstanding corrosion resistance and environmentally friendly. Nevertheless, the low electrical conductivities and poor specific capacities are the main obstacles of developing this material to practical application. Doping is an effective method to solve these problems. In this paper, nanosized LaFeO 3 -based solid solutions doped with Co3+, Mn3+, and Li+ ions were synthesized via sol-gel method, and the contents of the doped ions are set as 0.10. The substitution positions of the doped ions were discussed. The microstructure tests revealed that the doped samples were single phase structures, and the crystallite sizes of the doped samples were smaller than that of the undoped LaFeO 3. The dispersion degrees of the doped samples were improved. The results of the spectra tests demonstrated that the doped ions decreased the band gap energies, the Co3+ and Mn3+ ions influenced the frequencies of Fe–O stretching vibrations, and partial replacement of La3+ ions by Li+ ions induced the shift of vibration modes of the La–O bond. Electrochemical hydrogen storage measurements showed that the doped samples possess significantly better properties than that of the undoped LaFeO 3. Thereinto, the maximum discharge capacity of the Co3+ ion doped sample reached to 414 mAh/g at the 14th cycle and remained stable at around 400 mAh/g within the following cycles. Kinetic results further proved that the doped samples showed better performances. The hydrogen storage properties of doped LaFeO 3 are closely associated with the contents of the oxygen vacancies and defects in the lattice of samples. In addition, the characteristics of the doped ions also play important roles in improving the hydrogen storage properties of the LaFeO 3 -based oxides. [ABSTRACT FROM AUTHOR]

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A series of superconducting samples including pure Bi2Sr2Ca2C3O10 (BSCCO), Pb-doped BSCCO (Bi1.35Pb0.65Sr2Ca2Cu3O10), Mg-doped BSCCO (Bi1.65Mg0.35Sr2Ca2Cu3O10), and optimally co-doped Pb-Mg-BSCCO with an optimal formula of BiPb0.65Mg0.35Sr2Ca2Cu3O10 (108K superconductor) were carefully synthesized and optimized with a maximum ratio of incorporated lead and magnesium, achieving both quality of structural features and an improved Tc offset of 108 K. The optimized porous sample was well characterized via x-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), and three-dimensional atomic force microscopy (3D-AFM). In addition, the Brunauer–Emmett–Teller (BET) specific surface area was estimated at 11.9 m2g−1. Porous Mg-doped BPSCCO exhibited high performance efficiency for H2 storage, recording maximum H2 uptake of 5.92 wt.% at a temperature of 270°C and pressure of 14 bar. A mechanism of loaded hydrogen was proposed. Magnesium and lead incorporated in 2223-BPSCCO were suggested to play a vital role in hydrogen storage as Mg hydride and Pb as plumbane. [ABSTRACT FROM AUTHOR]

The porous underground structures have recently attracted researchers' attention for hydrogen gas storage due to their high storage capacity. One of the challenges in storing hydrogen gas in aqueous solutions is estimating its solubility in water. In this study, after collecting experimental data from previous research and eliminating four outliers, nine machine learning methods were developed to estimate the solubility of hydrogen in water. To optimize the parameters used in model construction, a Bayesian optimization algorithm was employed. By examining error functions and plots, the LSBoost method with R² = 0.9997 and RMSE = 4.18E-03 was identified as the most accurate method. Additionally, artificial neural network, CatBoost, Extra trees, Gaussian process regression, bagged trees, regression trees, support vector machines, and linear regression methods had R² values of 0.9925, 0.9907, 0.9906, 0.9867, 0.9866, 0.9808, 0.9464, and 0.7682 and RMSE values of 2.13E-02, 2.43E-02, 2.44E-02, 2.83E-02, 2.85E-02, 3.40E-02, 5.68E-02, and 1.18E-01, respectively. Subsequently, residual error plots were generated, indicating the accurate performance of the LSBoost model across all ranges. The maximum residual error was − 0.0252, and only 4 data points were estimated with an error greater than ± 0.01. A kernel density estimation (KDE) plot for residual errors showed no specific bias in the models except for the linear regression model. To investigate the impact of temperature, pressure, and salinity parameters on the model outputs, the Pearson correlation coefficients for the LSBoost model were calculated, showing that pressure, temperature, and salinity had values of 0.8188, 0.1008, and − 0.5506, respectively, indicating that pressure had the strongest direct relationship, while salinity had an inverse relationship with hydrogen solubility. Considering the results of this research, the LSBoost method, alongside approaches like state equations, can be applied in real-world scenarios for underground hydrogen storage. The findings of this study can help in a better understanding of hydrogen solubility in aqueous solutions, aiding in the optimization of underground hydrogen storage systems. [ABSTRACT FROM AUTHOR]

This article presented a robust plan for an off-grid charging station (OGCS) for electric vehicles (EVs) and hydrogen vehicles (HVs) based on a photovoltaic (PV) system and a hydrogen storage system (HSS). This OGCS simultaneously supplies HVs and EVs continuously throughout the day. Also, HSS and fuel cell (FC) systems have been allocated in the OGCS to be used when we do not have access to the power of the PV system. In addition, a diesel generator (DG) is also designed to prevent in cases where we have extreme uncertainty, including the lack of energy in the PV system and the high load of the system, which may lead to load interruption. Uncertainties of electric and hydrogen loads of EVs and HVs in addition to PV production power are simulated using scenario-based stochastic optimization technique (SOT). Finally, a new framework based on stochastic p-robust optimization technique (SPROT) is applied to optimize the maximum relative regret (MRR) in the worst scenario in order to achieve robust planning in the uncertain environment. The obtained results from the proposed SPROT are compared with SOT. The compared results indicate a 4.51% raise in the average cost in SPROT and a 45.73% decrease in MRR that leads to robust planning. Finally, installed capacity of PV system will decrease from 1688 to 1685 kW, while installed capacity of DG will increase from 78 to 123 kW. • Off-grid charging station for electric and hydrogen vehicles is studied. • PV system, fuel cell and hydrogen storage system are considered. • Diesel generator is designed to prevent in cases where we have extreme uncertainty. • Uncertainties of electric and hydrogen loads, photovoltaic power are considered. • Stochastic p-robust optimization technique is proposed to minimize MRR. [ABSTRACT FROM AUTHOR]

Catalysts with hydrogen spillover mechanisms can significantly enhance the hydrogen storage density of carbon-based porous materials under ambient conditions, attributed to its hydrogen adsorption energy improving by cracking hydrogen molecules into active hydrogen (hydrogen ions or hydrogen radicals), which is considered as a promising strategy for optimizing hydrogen storage performance of porous materials. The developing of non-noble metal based catalysts with hydrogen spillover mechanisms is currently a research hotspot and development direction. Based on this, the catalyst research progresses based on the non-noble metal materials are summarized to clarifies the factors affecting the hydrogen spillover effect of non-noble metal based catalysts. This article looks forward to the research and development direction of non-noble metal based catalysts for carbon-based porous materials, which hope to promote the development of non-noble metal based catalysts and accelerate the industrial application of porous solid hydrogen storage materials. [Display omitted] • The preparation of non-noble metal based catalysts with hydrogen spillover mechanism is analyzed in this article. • To achieve substitutive applications of noble metal catalysts, its spillover mechanism for the H 2 storage of carbon-based hydrogen storage materials. • An in-depth analysis is conducted on the enhancement of H 2 storage performance under ambient conditions by the hydrogen spillover mechanism. [ABSTRACT FROM AUTHOR]

The multi-energy complementary system (MECS) is a new mode that converts renewables into electricity and is usually equipped with hydrogen storage. It realizes flexible conversion of electric and hydrogen energy, achieving high efficiency and low carbon. However, how to optimize capacity of each equipment based on operation strategies and objectives becomes the most important issue. Thus, this study focuses on MECS optimal allocation and manages to work out a scientific framework. Firstly, the Density-Based Spatial Clustering of Applications with Noise algorithm and the Calinski Harabasz Index are firstly integrated to improve K-means clustering algorithm and identify typical scenarios. It can efficiently deal with long-sequence scenario reduction under the uncertainty of generation and load demand. Then, different from conventional objective-determining processes, indicators of the net present value, the carbon emission reduction, the power curtailment rate are taken into account to reflect comprehensive benefits from the life cycle of the MECS. Subsequently, for the difficulty of mixed integer fraction optimization, the -constraint method is introduced in model solving. Finally, a case study of Shenzhen is carried out for verification. The proposed models can achieve optimal allocation with different preference, which can provide theoretical and technical reference for MECS development. [Display omitted] • Industrial park multi-energy complementary system with hydrogen storage is built. • DBSCAN algorithm is introduced to extract typical scenarios based on cluster analysis. • Comprehensive benefits are taken into account in configuration optimization. • An ε-constraint is applied to solve the mixed integer fraction optimization problem. • Theoretical and technical reference is provided for low-carbon and green transition. [ABSTRACT FROM AUTHOR]

Recently, hydrazine borane (HB, N 2 H 4 BH 3) is recognized as an ideal chemical hydrogen storage material due to its high efficiency in storing hydrogen and excellent stability. However, finding an efficient, stable, and low-cost catalyst is still a challenge. In this study, CoPt nanoparticles (NPs) supported on carbon nanotubes (CNTs) are prepared at room temperature. The Co 0. 4 Pt 0.6 /CNTs catalyst exhibits optimal catalytic performance for hydrogen production from HB at ambient conditions, achieving a total turnover frequency (TOF) value of 1525.4 h−1 and 100% H 2 selectivity. The well-dispersed CoPt NPs on CNTs and the synergistic effect between Co and Pt further enhance the decomposition efficiency of HB. This high-performance catalyst has significant implications for the advancement of hydrogen storage materials, particularly in relation to HB. [Display omitted] • Co 0·4 Pt 0.6 /CNTs exhibit high activity and durability for N 2 H 4 BH 3 hydrolysis. • Co 0·4 Pt 0.6 /CNTs provide record turnover frequency value of 1525.4 h−1 for N 2 H 4 BH 3 dehydrogenation at 298 K. • Co 0·4 Pt 0.6 /CNTs achieve 100% H 2 selectivity in N 2 H 4 BH 3 dehydrogenation reaction. [ABSTRACT FROM AUTHOR]

Investigations were carried out in this paper to study the influence of rapid decompression rate on the polyamide 6 (PA6) liner materials through experimental and numerical methods. Firstly, hydrogen permeation tests at different pressures were conducted to obtain the functions representing the trend of permeation parameters with the pressure. Then decompression tests at different decompression rates had been carried out to get whitening specimens which would be observed using scanning electron microscopy (SEM). Cavitation was found and the variety of the number of cavities with the decompression rate was recorded. It was found that the faster the decompression rate was, the higher the number of cavities in the specimen was. Thirdly, to determine the hydrogen concentration throughout the specimen and numerically check if cavitation occurred at various decompression rates, a 2D finite element model was established which introduced the permeation parameters as functions of pressure but not temperature, as another numerical model indicated the temperature field of specimens changed little. Then an approach was proposed to successfully implement the risk assessment of cavitation, and the liner material was considered as elastoplastic neglecting its viscoelasticity-viscoplasticity. Based on the assumptions and experimental conditions in the study, the Mises yield criterion was successful to assess the cavitation risk, and the approach was verified as the analysis results about the cavitation agree well with the SEM observations. In the end, based on the approach, it could be concluded that 11h was the critical safe decompression time for the PA6 material in this study, and the decompression rate was 7.95 MPa/h. The approach in this study can also be used as guidelines for the cavitation risk assessment of other systems and materials undergoing rapid decompression. • Permeation parameters of PA6 material in gaseous hydrogen are measured under 15 MPa, 43.75 MPa, 87.5 MPa. • The effect of pressure on permeation coefficients is considered in the present diffusion model. • Through SEM observations it is found that the number of cavities rises with the increasing decompression rate. • The safety decompression rate is calculated considering the mechanical equilibrium and hydrogen diffusion in cavities. [ABSTRACT FROM AUTHOR]

The limited practical application of commercial MgH 2 is hindered by its sluggish hydrogen absorption and desorption kinetics. In this paper, MgH 2 particles with smaller sizes were successfully prepared by mechanical ball milling, and the microstructure of ball-milled MgH 2 was analyzed by XRD, SEM, and TEM. The addition of ball milling energy increases the surface energy of the material and the fracture of the Mg–H bond. As a result, the surface activation energy of the material is reduced. Furthermore, extending the milling duration results in a notable expansion of the nanocrystalline domains present on the surface of MgH 2 powder. At 613 K, the MgH 2 ball milled for 15 h can absorb 5.512 wt% H 2 in 7.8 min, and it takes 75 min to release 5.124 wt% H 2 and its dehydrogenation activation energy is reduced from 136.0 to 126.69 kJ/mol H 2. The initial dehydrogenation temperature of the MgH 2 sample milled for 15 h was 81 K lower than that of the original MgH 2 sample, and the initial dehydrogenation temperature was only 447 K. This work can provide theoretical guidance for the use value of commercial MgH 2. [Display omitted] • Nanocrystals produced by ball milling are beneficial to the hydrogen storage of MgH 2. • Ball milling can increase the specific surface area of Mg to enhance the activity. • Excessive ball milling will produce amorphous crystals. • The ball milling process introduces defects and accelerates the diffusion of H atoms. • The MgH 2 milled for 15 h can absorb 5.512 wt% H 2 in 7.8 min. [ABSTRACT FROM AUTHOR]

In this work, we use first-principles to calculate the structural, mechanical, electronic, dynamic, thermodynamic, optical and hydrogen storage properties of XMoH 3 (X = Na, K, Rb, Cs) for the first time. Our calculated formation energy, elastic constants and phonon spectra show that XMoH 3 perovskites are thermodynamically, mechanically, and dynamically stable. The investigation of B/G ratio, Cauchy pressure and Poisson's ratio shows that NaMoH 3 , KMoH 3 and RbMoH 3 are brittle materials, while CsMoH 3 is the tough material. In addition, the anisotropy factor, wave velocity and Debye temperature of these hydrides were calculated. The band structures of XMoH 3 hydrides suggest that KMoH 3 and RbMoH 3 are metallic materials, while NaMoH 3 and CsMoH 3 are half-metallic compounds. The optical properties of these hydrides in the range of 0 – 40 eV were studied. We found that these compounds own high polarization and high reflection. The gravimetric hydrogen storage capacities of NaMoH 3 , KMoH 3 , RbMoH 3 and CsMoH 3 are 2.48 wt%, 2.19 wt%, 1.64 wt% and 1.30 wt%, respectively, and their hydrogen desorption temperatures are 498 K, 413 K, 385 K and 345 K, respectively. The thermodynamic properties, including entropy, free energy, enthalpy and heat capacity of XMoH 3 were also investigated. Our studies indicate that NaMoH 3 has the highest potential as an efficient hydrogen storage material. • XMoH 3 (X = Na, K, Rb, Cs) perovskites have been investigated using first-principles. • XMoH 3 compounds exhibit thermodynamic, mechanical, and dynamical stability. • The gravimetric hydrogen storage capacity is found to be 2.48 wt% for NaMoH 3. [ABSTRACT FROM AUTHOR]

ZrCo alloy is considered as a promising candidate for hydrogen isotope storage in nuclear fusion reactors. However, severe poisoning caused by the impurities contained in hydrogen is an inevitable issue in engineering applications. Herein, the effects of Cr-doped ZrCo with segregated the reticular ZrCr 2 phase on the activation and oxidation resistance were investigated systematically. Experimental results show ZrCo 0·95 Cr 0.05 can achieve 1.71 wt% hydriding capacity within about 37 min under 1 mol% O 2 + 99 mol% H 2 , whereas ZrCo consumes more than 4 times (150 min) to reach the same capacity. Specifically, the improved anti-poisoning ability of the ZrCo–Cr system could be attributed to the three-step chain effect induced by Cr doping, including the hydrogenation-prone and oxygen resistance character of ZrCr 2 phases, sacrificial and catalysis of in-situ formed metallic Cr clusters, and protective effects of Cr oxide layers. Hence, the active sites for rapid hydrogen absorption were obtained and inferior oxygen resistance of ZrCo substrates was alleviated through the self-sacrifice of ZrCr 2 and Cr. This work not only proves the feasibility of the multi-component alloying strategy in the field of ZrCo alloy anti-poisoning modification, but also reveals that the core of the multi-component alloying strategy is to realize the modulation of the microstructure through the composition design. The layer-to-layer stacking relationship and oxidation dynamic behavior of Cr-doped ZrCo under the O 2 /H 2 mixed gas is vividly illustrated. [Display omitted] The Cr-doped ZrCo with a Cr-rich reticular second phase structure was constructed flexibly. •Facilitated activation kinetics under H 2 and poisoning resistance under 99% H 2 + 1% O 2 were obtained. •The stacking relationship and dynamic oxidation behavior of Cr-doped ZrCo are vividly illustrated. •The self-sacrificial mechanism of segregated ZrCr 2 phases and in-situ formed metallic Cr clusters under the action of oxygen was revealed. [ABSTRACT FROM AUTHOR]

Renewable energy sources, such as hydrogen play a crucial role in developing sustainable technologies. Hydrogen is one of the best candidates for future energy transition. Today, hydrogen storage techniques have become an important and debated issue in many countries. This study represents the first attempt to prepare CuCr 2 O 4 nanoparticles using two different methods (sol-gel and green) and compare their performance as an electrocatalyst in electrochemical hydrogen storage. The tetragonal crystal structure, spherical shape, purity, and mesoporous features of the sample were studied using X-ray diffraction (XRD), Fourier transform infrared (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDS), and Brunauer-Emmett-Teller (BET) techniques. Additionally, the hydrogen storage performance of CuCr 2 O 4 nanoparticles was investigated using cyclic voltammetry (CV), and charge-discharge chronopotentiometry (CP) in a 3 M KOH alkaline medium. The result revealed that the specific capacitance values of CuCr 2 O 4 nanoparticles in sol-gel and green methods were obtained to be 2427 and 1503 Fg-1, respectively. The discharge capacities of CuCr 2 O 4 nanoparticles in sol-gel and green methods after 11 cycles were calculated to be 4304 and 3011 mAh/g, respectively. The superior hydrogen storage capability of CuCr 2 O 4 nanoparticles in the sol-gel method can be attributed to its high porosity. [Display omitted] • CuCr 2 O 4 nanoparticles were synthesized using the sol-gel and green methods. • Study of crystal structure, morphological, and electrochemical properties of the samples. • CuCr 2 O 4 showed excellent hydrogen storage capacity of 4304 and 3011mAh/g in the sol-gel and green methods, respectively. • A promising material for hydrogen storage applications. [ABSTRACT FROM AUTHOR]

LaNi 5 -based alloy is capable of storing and purifying hydrogen, however, it is susceptible to poisoning by impurities like O 2 and CO, ultimately diminishing its hydrogen storage performance. In this paper, a comprehensive study on the effect of oxygen on the gas adsorption properties of LaNi 4.25 M 0.75 (M = Co, Mn) and the effect of different oxygen concentrations and temperatures on LaNi 4. 25 Mn 0.75 was conducted. The results reveal that the gas adsorption capacity of LaNi 4.25 M 0.75 (M = Co, Mn) alloys increased from 150.73 ml/g and 136.51 ml/g to 186.37 ml/g and 165.04 ml/g, respectively, after introducing 1000 ppm oxygen during the initial exposure cycle. This augmentation is primarily attributed to the reaction between H 2 and O 2 , leading to the formation of H 2 O. As the number of poisoning cycles increases, the gas adsorption capacity of the alloys tends to decrease. Under varying oxygen concentrations, a higher oxygen content exerted more pronounced effects on LaNi 4. 25 Mn 0.75 , potentially linked to the accelerated rate of oxidation layer coverage with increasing oxygen levels. Regarding temperature variations, the LaNi 4. 25 Mn 0.75 alloy exhibited superior resistance to O 2 at higher temperatures compared to low temperatures. This is explained by the fact that impurity gases are more easily desorbed at elevated temperatures, thereby enhancing the likelihood of H 2 adsorption on the alloy surface. • Comprehensive O 2 on the hydrogenation/dehydrogenation performance of LaNi 4.25 M 0.75 (M = Co, Mn) alloys is systematically investigated. • The gas adsorption capacity of LaNi 4.25 M 0.75 (M = Co, Mn) alloys increased from 150.73 ml/g and 136.51 ml/g to 186.37 ml/g and 165.04 ml/g, respectively, after introducing 1000 ppm oxygen during the initial exposure cycle. • Under varying oxygen concentrations, a higher oxygen content exerted more pronounced effects on LaNi 4. 25 Mn 0.75. • The LaNi 4. 25 Mn 0.75 alloy exhibited superior resistance to O 2 at higher temperatures compared to low temperatures. [ABSTRACT FROM AUTHOR]

Semicrystalline polyamides (PAs) are optimal materials to develop high-pressure resistant liners for type IV hydrogen storage tanks due to a favorable combination of barrier performance, mechanical resistance, and lightness. However, experimental data on hydrogen transport in PAs are incomplete or inconsistent, and usually do not report separately the contributions of solubility and diffusivity, hence limiting a deep understanding of the permeation mechanism and its dependence on the material structure. Moreover, recent developments have led to the design of modified polyamides which could better serve the high-pressure storage applications. In this work, the hydrogen barrier performance of Polyamide 6 (PA6), Polyamide 11 (PA11) and an impact-modified PA 6 (PA6-I), was evaluated and the results obtained with different techniques and on different samples compared. Permeation measurements were performed in constant-volume and constant-pressure apparatuses at different temperatures and pressures, on different samples of each material. Sorption measurements were carried out into a differential sorption system. Results from the permeation and sorption devices were compared against each other and with literature data, allowing to understand the effect of various factors. The H 2 solubility in PA is mostly affected by density, as a lower free volume of the amorphous phase leads to a lower gas uptake. On the other hand, diffusivity and, consequently, permeability, are also strongly affected by the morphology of the crystal phase, which depends on the production protocol. In most of the cases inspected, the discrepancy between data from different experimental techniques or literature works can be explained by the different crystal morphology of the samples used in the test. Temperature enhances diffusivity, permeability and solubility, while the pressure reduces the permeability, as it lowers the free volume, and increases the activation energy of permeation. An estimation of the minimum thickness required to meet high-pressure storage technical guidelines was provided for the case of PA6-I. • H 2 sorption and transport in commercial polyamides (PA6, PA6I, and PA11) was tested. • Three techniques were compared: sorption, permeation and high-pressure permeation. • Different temperatures up to 80 °C and pressures up to 700 bar were studied. • Experimental data are in agreement and differences were properly motivated. • PA6 is the best material and a minimum thickness to meet EU 406/2010 was determined. [ABSTRACT FROM AUTHOR]

Titanium alanate Ti(AlH4)4 is a candidate material for high‐density hydrogen storage that thus far has been scarcely investigated. This study determines the low energy structures of Ti(AlH4)4 by adopting a global optimization algorithm combined with density functional theories, and systematically compares their stabilities, electronic structures, and bonding properties with Mg(AlH4)2 and Ca(AlH4)2. Compared to other compounds, Ti(AlH4)4 is less stable and the Ti−H bond is of covalent nature with strong polarities. The covalent Ti−H interaction can weaken the Al−H bonds. Because both the ionic and covalent interactions of the Al−H bonds are the weakest in Ti(AlH4)4, it is favorable for the desorption of hydrogen. [ABSTRACT FROM AUTHOR]

Using first principles calculations, the hydrogen storage, mechanical, dynamic, thermodynamic, electronic and optical properties of YCrH 3 (Y = Ca, Sr, Ba) materials are studied for the first time. The lattice constants of CaCrH 3 , SrCrH 3 and BaCrH 3 are 3.70, 3.88 and 4.07 Å, respectively. Exploration of the mechanical properties shows that both CaCrH 3 and BaCrH 3 are brittle, whereas SrCrH 3 is ductile. In addition, all compounds are metallic, thus facilitating efficient charge transfer during hydrogen storage and release. According to the Bader partial net charges, the charge transfer in the YCrH 3 materials is analyzed. The electron density distributions show that the CaCrH 3 hydride contains ionic and covalent bonds, whereas SrCrH 3 and BaCrH 3 are ionic hydrides. Studies of optical properties reveal that CaCrH 3 has the largest static refractive index and dielectric constant. Notably, all the studied hydrides exhibit dynamic, thermodynamic and mechanical stability. The gravimetric hydrogen storage capacities are 3.08, 2.08 and 1.55 wt% for CaCrH 3 , SrCrH 3 and BaCrH 3 , respectively. These investigations provide an important theoretical basis for further exploring the application of hydride materials in the field of hydrogen storage. [ABSTRACT FROM AUTHOR]

Several studies have reported about different hydrogen production and storage materials. The use of metal oxides, particularly iron oxides, as hydrogen storage materials offers a promising solution to bridge hydrogen production and utilization. The iron‐steam process, dating back to the 18th century, leverages iron's ability to bind oxygen from steam, producing hydrogen and iron oxides. This study revisits the iron/iron oxide system for its dual application as a hydrogen storage medium and as an energy carrier in systems like fuel cells. When integrated with high‐temperature electrolysis and fuel cells, this system can efficiently operate between 600 and 1000 °C. The key to long‐term performance lies in understanding the formation and stability of oxygen‐binding structures. Stabilizing the iron oxides for cycling procedures with other metal oxides like Al2O3, SiO2, and CaO is inevitable. Ceramic‐stabilized iron oxide pellets offer advantages including high cycling capability, efficient charge/discharge operations, and potential syngas production. They are particularly suitable for heavy goods vehicles, short‐term storage, and large‐scale industrial applications. Critical process parameters for the iron oxide material and process design must be investigated if an accurate assessment of the performance of this hydrogen storage concept is to be transferred into efficient practice. [ABSTRACT FROM AUTHOR]

Metal hydrides provide a safe and efficient way to store hydrogen. However, current metal hydride storage systems, i.e., hydrides incorporated within a storage tank, are far from efficient. Depending on the design, (dis)charging rates may be very long. However, this can be significantly improved by implementing strategies tackling the issue of heat management at the level of: i) the metal hydride bed, and ii) the overall storage system design. This review summarises recent progress in tackling heat management of hydride systems. In this respect, modeling has emerged as a powerful tool. In particular, simulation results show that the compaction of hydride powders with binders and the use of metal foams are both effective in lifting the poor thermal conductivity of hydride beds. For tank designs, cylindrical shapes remain the preferred choice because of the flexibility and ease of supplementing heat management with fins and tubular heat exchangers. The addition of phase change materials to the hydride tank can lead to further heat storage, but any add‐on to simple hydride tanks can only lead to cumbersome systems. It is still a fine art to tune the thermal conductivity of hydride beds while selecting a suitable metal hydride alloy composition. [ABSTRACT FROM AUTHOR]

Hydrogen is a promising candidate for green energy sources for future endeavors because of its abundance on Earth. Although its storage is a major challenge for the researchers of this era because of its unsafe and highly explosive nature. The structural, optoelectronic, thermoelectric, vibrational, thermodynamic properties and hydrogen storage capacity of XMgH3 (X = Sr , Ba) are carried out by using the full potential linearized augmented plane wave (FP-LAPW) method in the DFT framework. The theoretical study about these magnesium-based metal hydride perovskites, i.e., SrMgH3 and BaMgH3, declares them structurally stable compounds in space group Pm-3m. The optimization graph for SrMgH3 and BaMgH3 reflects the lowest ground state energy, i.e., −6759 Ry and −16683 Ry, respectively. Comparatively, BaMgH3 seems to be more stable. The electronic band structures and density of states declare them pure metallic due to zero band gap and overlapping of electronic states of the valence and the conduction bands. The electrical conductivity of BaMgH3 increases up to 4. 5 × 1 0 2 0 (Ω ⋅ m ⋅ s) − 1 and thermal conductivity 1. 2 5 × 1 0 1 6 (Ω ⋅ m ⋅ s) − 1 in the temperature range 100 K to 1000 K revealing the good metallic character of BaMgH3. The optical analysis portrays the absorption of compounds in the visible range along with valance shell electrons to the weak bond of hydrogen and dissociates hydrogen molecules at a certain intensity of light. BaMgH3 compound shows minimum scattering and maximum absorption of light in the visible region up to 3 eV. The reflectivity peaks in the visible region 3.0 eV show that 40% of light energy is absorbed due to the opaque nature of BaMgH3. Both these compounds are declared thermodynamically stable due to negative free energy such as −1.20 eV for SrMgH3 and −1.50 eV energy for BaMgH3 at 1000 K, respectively. Moreover, the three acoustic modes showing zero imaginary phonon frequencies at Γ symmetry points predict these compounds' structural and thermodynamical stability. The gravimetric hydrogen storage concentration of SrMgH3 and BaMgH3 is determined as 2.637% and 1.836%, respectively. [ABSTRACT FROM AUTHOR]

Efficient catalysis of ammonia borane (AB) holds potential for realizing controlled energy release from hydrogen fuel and addressing cost challenges faced by hydrogen storage. Here, we report that amorphous domains on metallic Fe crystal structures (R-Fe2O3 Foam) can achieve AB catalytic performances and stability (turnover frequency (TOF) of 113.6 min−1, about 771 L H2 in 900 h, and 43.27 mL/(min·cm2) for 10×10 cm2 of Foam) that outperform reported benchmarks (most <14 L H2 in 45 h) by at least 20 times. These notable increases are enabled by the stable Fe crystal structure, while defects and unsaturated atoms in the amorphous domains form Fe-B intermediates that significantly lower the dissociation barriers of H2O and AB. Given that the catalyst lifetime is a key determinant for the practical use in fuel cells, our R-Fe2O3 Foam also provides decent H2 supply (180 mL H2/min, AB water solution of 7.5 wt% H2) in a driven commercial car fuel cell at stable power outputs (7.8 V and 1.6 A for at least 5 h). When considered with its facile synthesis method, these materials are potentially very promising for realizing durable high-performance AB catalysts and viable chemical storage in hydrogen powered vehicles. Hydrogen storage and release are critical issues for commercial use. Here, authors report a Fe Foam with amorphous domains for the hydrolysis of ammonia borane with ultra-long lifetime over 900 h, realizing the on-board H2 supply of a model car. [ABSTRACT FROM AUTHOR]

[Cp*Ir(R‐pica)Cl] (Cp*=pentamethylcyclopentadienyl anion, pica=2‐picolineamidate) complexes bearing carbohydrate substituents on the amide nitrogen atom (R=methyl‐β‐D‐gluco‐pyranosid‐2‐yl, 1; methyl‐3,4,6‐tri‐O‐acetyl‐β‐D‐glucopyranosid‐2‐yl, 2) were tested as catalysts for formic acid dehydrogenation in water. TOFMAX values over 12000 h−1 and 50000 h−1 were achieved at 333 K for 1 and 2, respectively, with TON values over 35000 for both catalysts. Comparison with the simpler cyclohexyl‐substituted analogue (3) indicated that glucosyl‐based complexes are much better performing under the same experimental conditions (TOFMAX=5144 h−1, TON=5000 at pH 2.5 for 3) owing to a lower tendency to isomerize to the less active k2‐N,O isomer upon protonation. The 5‐fold increase in TOFMAX observed for 2 with respect to 1 is reasonably due to an optimal steric protection by the acetyl substituent, which may prevent unproductive inner‐sphere reactivity. These results showcase a powerful strategy for the inhibition of the common deactivation pathways of [Cp*Ir(R‐pica)X] catalysts for FA dehydrogenation, paving the way for the development of better performing hydrogen storage systems. [ABSTRACT FROM AUTHOR]

Multivariate metal-organic frameworks (MTV-MOFs) are characterized by their unique structural feature of incorporating multiple organic linkers and metal ions into a unified framework. This composite construction bestows MTV-MOFs with a broader spectrum of diverse and intricate properties compared to traditional single-component MOFs. In this study, the performance of 560 MTV-MOFs as hydrogen storage adsorbents has been thoroughly investigated. Firstly, the key structural parameters of materials, including density, pore occupied accessible volume, accessible surface area, and porosity were computed. Then, high-throughput Grand Canonical Monte Carlo (GCMC) simulations were employed to calculate hydrogen adsorption capacity of MTV-MOFs under hydrogen pressures of 100 bar at both 77 K and 298 K. Based on simulated results, the deliverable hydrogen capacity of these MTV-MOFs were deduced under both room temperature conditions (298 K, 97.2 bar → 298 K, 5 bar) and low-temperature conditions (77 K, 100 bar → 160 K, 5 bar). Through high-throughput screening, we identified top ten promising MTV-MOFs with the highest hydrogen storage capacity and conducted in-depth studies on their hydrogen adsorption properties. Furthermore, we developed a multivariate linear regression model to quantitatively predict the relationship between hydrogen adsorption capacity and their structural parameters for these MTV-MOFs. The predictions of this model align closely with the outcomes derived from GCMC simulations. The present study highlights the potential of MTV-MOFs as promising candidates for hydrogen storage applications, thereby providing valuable theoretical insights into the exploration of high-capacity hydrogen storage materials. • Structural parameters and H 2 adsorption properties of 560 MTV-MOFs are studied. • Structure-activity relationships are systematically studied by statistical analysis. • The top ten MTV-MOFs with the best H 2 storage performance are identified. • Machine learning method is used to develop a multivariate linear regression model. [ABSTRACT FROM AUTHOR]

Co 2 B, with its high theoretical hydrogen storage capacity, is a potential solid-state hydrogen storage material. However, its poor cycling life limits its practical application. In this work, in order to improve the cycling stability and reversibility of hydrogen absorption and desorption of Co 2 B, we propose to use WO 2 –N–C nanosheets as dopants to mix with Co 2 B, thereby enhancing its practical performance. Two-dimensional tungsten oxide-nitrogen-carbon (WO 2 –N–C) nanosheets was syntheized via a liquid-phase approach, using a tungstenate-polydopamine precursor followed by thermal treatment. Subsequently, these WO 2 –N–C nanosheets were compounded with cobalt boride (Co 2 B) particles through ball milling at various ratios of 1%, 3%, and 5%, which were confirmed by XRD (X-ray diffraction) and SEM (Scanning Electron Microscope) methods. Employing a comprehensive suite of electrochemical analyses, including corrosion potential measurements, polarization curves, step voltammetry, and electrochemical impedance spectroscopy (EIS), we found that the incorporation of WO 2 –N–C significantly enhances the corrosion resistance and electrochemical activity of Co 2 B. Furthermore, cyclic life tests revealed that the WO 2 –N–C-doped Co 2 B composites exhibit superior discharge capacities and capacity retention rates compared to pristine Co 2 B. Notably, the 3% WO 2 –N–C-doped Co 2 B composite demonstrated the optimal electrochemical performance, achieving a maximum discharge specific capacity of 555 mAh g−1 and maintaining 82% of its initial capacity after 50 cycles. Our findings underscore the dual role of WO 2 –N–C in not only augmenting the surface electrochemical activity of Co 2 B but also providing a protective surface layer, thereby enhancing its overall electrochemical performance. • WO 2 –N–C were compounded with Co 2 B particles via ball milling at optimized ratios. • WO 2 –N–C improves the corrosion resistance and electrochemical activity of Co 2 B. • WO 2 –N–C-doped Co 2 B exhibit better discharge capacities and capacity retention rates. [ABSTRACT FROM AUTHOR]

A new materials composed of TiFe particles stabilized onto a carbon support is described. The carbon support is derived from a waste from the paper industry called Kraft Black liquor. The particles are generated through an impregnation/reduction process of a mixture of titanium ethoxide and iron nitrate followed by a thermal treatment. The generated particles have been investigated through XPS, XRD and SEM analysis as well as tested for hydrogen storage. The hydrogen storage at 25 °C leads to a capacity of up to 0.5 wt% while at 150 °C, free of the carbon absorption, leads to a capacity of 0.2 wt% without any prior activation process. Novel TiF@carbo(HIPE) materials have been synthesized while employing Kraft black liquor as carbonaceous source. A specific carbo-reduction thermal treatment allows a synergetic TiFe particles external shell reduction concomitant with the surrounding carbonaceous backbone oxidation enhancing thereby the materials specific surface area and associated microporosity. Pre-activation free, TiFe@Carbo(HIPE) can achieve a capacity up to 0.5 wt% at 25 °C where TiFe particles and the carbonaceous host support are acting cooperatively. [Display omitted] • Generation and characterization of carbon from a waste from the paper industry. • Generation of TiFe nanoparticles on the carbon. • Characterization of the TiFe nanoparticles. • Use of the hybrid composite TiFe@Carbon for hydrogen storage. [ABSTRACT FROM AUTHOR]

In this study, body-centered-cubic Ti 24 V 18 Nb 6 Cr 12 high entropy alloy (HEA) is selected as the matrix to design Mg–Ti–V–Nb–Cr lightweight HEAs. Based on first-principles calculations, the hydrogen storage properties of a series of Mg–Ti–V–Nb–Cr HEAs are systematically investigated. The designed Mg-based HEAs are found to be stable after hydrogenation and exhibit high gravimetric hydrogen storage capacities (HSCs). Particularly, the gravimetric HSC of Mg 6 Ti 24 V 18 Cr 12 HEA is as high as 4.091 wt%. Besides, the dehydrogenation temperature of the Mg–Ti–V–Nb–Cr HEAs decreases obviously with increasing Mg content, which results from the weakened bonding strength of pairs. This study demonstrates that the Mg 6 Ti 24 V 18 Cr 12 HEA is a potential candidate for hydrogen storage. • A series of Mg–Ti–V–Nb–Cr lightweight HEAs for hydrogen storage is designed. • The gravimetric hydrogen storage capacity of Mg6Ti24V18Cr12 is predicated to be as high as 4.091 wt% (H/M = 2). • The dehydrogenation temperature of the Mg–Ti–V–Nb–Cr HEAs decreases with increasing Mg content. [ABSTRACT FROM AUTHOR]

A successful transition to a sustainable economy depends on effective hydrogen storage. To achieve this, we investigate novel inorganic transition metal-based BaXH 3 (X = V, Cr, Co, Ni, Cu, Zn) perovskites using Density Functional Theory (DFT). We compute key properties such as structural, electrical, magnetic, optical, mechanical, and hydrogen storage using the GGA-PBE functional. We calculate lattice constants and unit cell volume, indicate thermochemical stability with the negative formation energy of all compounds, and confirm thermodynamic stability with phonon calculations. Investigations into the band structure and density of states (DOS) show that all compounds are metallic, with BaVH 3 and BaCrH 3 exhibiting magnetic characteristics. We calculate the optical properties, including refractive index, dielectric function, reflectivity, loss function, conductivity, and absorption. We verified mechanical stability using the Born stability criteria. We calculated the hydrogen storage capacities and desorption temperatures. These results indicate that the studied compounds are potential candidates for hydrogen storage in a green economy. • DFT study examines novel BaXH 3 (X = V, Cr, Co, Ni, Cu, Zn) perovskites for hydrogen storage. • All compounds are thermodynamically stable with negative formation energy. • BaVH 3 and BaCrH 3 exhibit magnetic properties; the others are non-magnetic. • Hydrogen storage capacities range from 1.44% to 1.56% among the studied compounds. • Mechanical stability was confirmed for all compounds using the Born stability criteria. [ABSTRACT FROM AUTHOR]

Two-dimensional vanadium carbide (V 2 C) MXene has been confirmed the excellent catalytic activity on hydrogen storage of magnesium hydride (MgH 2) in experimental. In present work, adsorption energy, density of states (DOS), charge density difference, dissociation barrier and dehydrogenation energy of the small MgH 2 clusters on V 2 C and V 2 CT 2 (T = O, F, and OH) were investigated by using density functional theory (DFT). The results revealed that the (MgH 2) 1 cluster adsorbed on the V 2 C has the best adsorption energy with −0.91eV and the lengths of Mg–H bonds were increased from 1.71 Å to 1.77 Å. The electronic structure results displayed that the H s states hybridized with the V d states, and the charge transferred from H atoms to V atoms. In addition, the (MgH 2) 1 cluster could be spontaneously dissociated on the V 2 C, and the dissociation barriers of (MgH 2) 2 and (MgH 2) 4 clusters on the V 2 C reduced by 1.33 and 1.25 eV than that of pristine (MgH 2) 2 and (MgH 2) 4 clusters, respectively. Compared with the pristine (MgH 2) 4 cluster, the dehydrogenation energies of (MgH 2) 4 cluster were dramatically promoted by adding V 2 C. The thermodynamic performance of MgH 2 were noticeably improved. [Display omitted] • Structures of V 2 C and V 2 CT 2 are optimized, and their stabilities are discussed. • Adsorption and dissociation performance of (MgH 2) n (n = 1,2,4) clusters on the V 2 C are studied. • MgH 2 molecules can be spontaneously dissociated on the V 2 C. • Dissociation energy of Mg 2 H 4 /Mg 4 H 8 +V 2 C is decreased significantly. • Compared with pristine Mg 4 H 8 , the dehydrogenation energy of Mg 4 H 8 +V 2 C is reduced. [ABSTRACT FROM AUTHOR]

Incorporating transition metal atoms and creating porphorin-like N 4 cavity are effective strategies for improving the hydrogen storage capability of carbon materials. In this view, we designed and addressed the hydrogen uptake properties of TM 4 C 8 N 8 (TM = Sc, Y, Ti) cages originating from C 24 to overcome TM clustering. The stabilities of three clusters were confirmed by molecular dynamic simulation. Sc 4 C 8 N 8 /Y 4 C 8 N 8 /Ti 4 C 8 N 8 can bind up to 20/20/36H 2 molecules with a higher gravimetric density of 9.35/6.67/15.27 wt%, compared to the goal of 5.5 wt% proposed by the US-DOE. The interaction between H 2 molecules and the hosts can be identified as van der Waals attractions. The average binding energies of Sc 4 C 8 N 8 (H 2) 20 /Y 4 C 8 N 8 (H 2) 20 /Ti 4 C 8 N 8 (H 2) 36 at M06(D3) and PBE(D3) functional are 0.159/0.173/0.128 eV/H 2 and 0.139/0.141/0.102 eV/H 2 , respectively, meeting the desirable range of reversible hydrogen storage. Furthermore, an investigation was conducted on the impact of pressure and temperature on the hydrogen storage capabilities of TM 4 C 8 N 8 (TM = Sc, Y, Ti). The desorption temperature exhibits a positive correlation with increasing pressure. The realization of hydrogen release at near mild conditions and the reversibility of hydrogen adsorption/desorption cycles were demonstrated using the van't Hoff equation and ADMP-MD simulations, respectively. Compared with the monomer, the hydrogen storage capacities of (TM 4 C 8 N 8) 2 (TM = Sc, Y, Ti) dimers are slightly reduced. [Display omitted] • Two novel TM-decorated and N-substituted defective C 24 fullerenes are designed and optimized by using two functionals. • MD simulations confirm the thermodynamic stability of the TM 4 C 8 N 8 (TM = Sc, Y, Ti) fullerenes. • The H 2 gravimetric density of Sc 4 C 8 N 8 /Y 4 C 8 N 8 /Ti 4 C 8 N 8 is 9.35/6.67/15.27 wt%. • H 2 molecules are strongly bound at 77 K and get efficiently released at elevated temperature. • The (Sc 4 C 8 N 8) 2 /(Y 4 C 8 N 8) 2 /(Ti 4 C 8 N 8) 2 dimer has a gravimetric density of 8.49/6.00/9.10 wt%. [ABSTRACT FROM AUTHOR]

In this work, the density functional theory is used to investigate the structural, mechanical, electronic, dynamic, thermodynamic, optical and hydrogen storage properties of XLiH 3 (X = K, Rb) for the first time. Both KLiH 3 and RbLiH 3 materials exhibit dynamic, mechanical and thermodynamic stability. The lattice parameters of KLiH 3 and RbLiH 3 are 3.908 and 4.070 Å, respectively. The investigation of Cauchy pressure, Poisson's ratio and B/G ratio shows that KLiH 3 and RbLiH 3 are brittle materials. Moreover, the electronic properties of XLiH 3 hydrides demonstrate that KLiH 3 and RbLiH 3 show metallic nature. Optical properties of these compounds are studied and reveal that they have very high refractive indexes and dielectric functions. The thermodynamic properties, including heat capacity, entropy, enthalpy, and free energy of XLiH 3 , are investigated as well. The hydrogen storage capacities of KLiH 3 and RbLiH 3 are 5.805 and 3.071 wt%, respectively, confirming that KLiH 3 has a high hydrogen storage capacity and is more suitable as a hydrogen storage material. Our study opens up a new-pathway for designing novel hydrogen storage materials. • XLiH 3 (X = K, Rb) perovskite hydrides have been investigated using first-principles. • XLiH 3 (X = K, Rb) exhibit thermodynamic, mechanical, and dynamical stability. • The hydrogen storage capacity of XLiH 3 is 5.805 wt% and 3.071 wt%, respectively. • Our studies propose that KLiH 3 is a more suitable hydrogen storage material. [ABSTRACT FROM AUTHOR]

The current work describes how 2D layered materials, such as MoS 2 and WS 2 , might improve the de/re-hydrogenation kinetics of MgH 2. In the presence of WS 2 catalyst, desorption of MgH 2 begins at 277 °C, with a hydrogen storage capacity of 5.95 wt%, while the onset desorption temperature of MgH 2 catalyzed by MoS 2 is 330 °C. In just 1.3 min at 300 °C under 13 atm hydrogen pressure, the MgH 2 -WS 2 absorbed approximately 3.72 wt% of hydrogen, and in 20 min at 300 °C under 1 atm hydrogen pressure, it desorbed around ∼5.57 wt% of hydrogen. To ensure the cyclic stability up to 25 cycles of de/re-hydrogenation of the catalyzed MgH 2 , a continuously 25 cycles of dehydrogenation (under 1 atm hydrogen pressure at 300 °C) and rehydrogenation (under 13 atm hydrogen pressure at 300 °C) were carried out. As a result, MgH 2 -WS 2 exhibits superior cyclic stability than MgH 2 –MoS 2. In addition, with the de/re-hydrogenation kinetics, MgH 2 -WS 2 has a lower reaction activation energy (∼117 kJ/mol) than to other catalyzed and pristine samples. Conversely, the thermodynamical parameters, specifically the change in enthalpy of MgH 2 , are unaffected by addition of these layered WS 2 and MoS 2 catalysts. • The meticulous and precise synthesis of WS 2 and MoS 2 2-D nanomaterials. • The remarkable catalyst of 2-D nanomaterials for the sorption properties of MgH 2. • 2-D WS 2 and MoS 2 are exceptional catalysts in the de- and re-hydrogenation kinetics of MgH 2. • 25 cycles of dehydrogenation and rehydrogenation on WS 2 /MoS 2 -catalyzed MgH 2. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive investigation of the electronic, mechanical, and thermodynamic properties of Zintl phase hydrides XGaSiH (X = Sr, Ca, Ba) using Density Functional Theory (DFT) and the FP-LAPW method within the WIEN2k package. Our analysis covers the structural stability, electronic properties, and hydrogen interaction mechanisms in these compounds. The hydrides exhibit narrow band gaps, with values ranging from 0.1 to 0.5 eV using GGA and LDA functionals, and 0.6–1.0 eV with mBJ-GGA and mBJ-LDA. The hydrogen storage capacities are determined to be 0.34 wt %, 0.47 wt %, and 0.40 wt % for SrGaSiH, CaGaSiH, and BaGaSiH, respectively, highlighting their potential for energy storage applications. Thermodynamic properties, evaluated through the quasi-harmonic Debye model, provide insights into the Grüneisen parameter, heat capacity, and thermal expansion coefficient over a range of pressures (0–50 GPa) and temperatures (up to 1000 K). Elastic constants reveal that these compounds are mechanically stable, with a notable anisotropy in the {100} plane and varying degrees of compressibility among the different hydrides. Our study further highlights the slightly ordered hexagonal Ga and Si layers, which contribute to the enhanced hydrogen storage capabilities of these materials. The compounds demonstrate high structural stability, facilitating effective hydrogen retention and release at practical temperatures, making them promising candidates for hydrogen storage applications. Additionally, the analysis of electronic band structures and density of states suggests significant conductivity potential, with band gaps ranging from 0.1 to 1.0 eV, depending on the computational method used. The unique combination of structural, electronic, thermodynamic, and mechanical properties in XGaSiH compounds positions them as valuable materials for renewable energy applications. These findings lay the groundwork for future research focused on optimizing these materials through structural modifications or doping to enhance performance metrics such as hydrogen storage capacity and electrical conductivity. [Display omitted] • Hydrogen storage properties of Zintl Phase Hydrides XGaSiH (X = Sr, Ca, Ba) have been investigated using DFT. • The mechanical stability test performed on the computed elastic constants Cij demonstrate that investigated compounds are mechanically stable. • The hydrogen storage capacity is 0.34%, 0.47%, and 0.40% for SrGaSiH, CaGaSiH, and BaGaSiH, respectively. • These materials could be useful for storage of hydrogen application. [ABSTRACT FROM AUTHOR]