Hydrogen Storage Capacity Research Articles

Insight into the mechanical, electronic, kinetic, thermodynamic, and hydrogen storage properties of XFeH3 (X=Ca, Sr, Ba) perovskites for hydrogen storage applications: First-principle calculations

Based on the first-principle calculations, the XFeH3 (X=Ca, Sr, Ba) hydrides have been systematically investigated. The lattice constant, elastic constants, bulk modulus, Poisson's ratio, and Young's modulus of XFeH3 hydrides are calculated. According to the B/G and Poisson's ratio, CaFeH3 and SrFeH3 exhibit brittleness, while BaFeH3 exhibits ductility. The electronic properties demonstrate that CaFeH3 and SrFeH3 exhibit half-metallic ferromagnetism, while BaFeH3 exhibits metallic ferromagnetism. We analyze the Bader partial net charges to better understand the charge transport in XFeH3 hydrides. In addition, the formation energy, Born stability criterion, and phonon dispersion curves of XFeH3 were investigated, which confirmed that XFeH3 perovskites are simultaneously thermodynamic, mechanical, and kinetic stable. The gravimetric hydrogen storage capacities of CaFeH3, SrFeH3, and BaFeH3 are 3.06, 2.06, and 1.54 wt%, respectively, revealing that CaFeH3 hydride can be a better material for hydrogen storage applications compared to SrFeH3 and BaFeH3. Our results would provide a new candidate for hydrogen storage materials.

Effect of Eu2O3@C composite catalyst on hydrogen storage performance of Mg96La3Ni alloy

This study successfully synthesized Eu2O3@C composite catalyst by an improved chemical blowing method. The Eu2O3 nanoparticles in this catalyst are highly dispersed within a porous carbon matrix, exhibiting a well-developed mesoporous structure, a large specific surface area, and a high density of defects. Eu2O3@C was mixed with the Mg96La3Ni alloy through ball milling, and the impact of varying amounts of Eu2O3@C on the hydrogen storage performance of Mg96La3Ni was comprehensively investigated. The results showed that Eu2O3@C markedly enhances the de/hydrogenation kinetics of Mg96La3Ni, with the most substantial impact noted at a Eu2O3@C content of 2 wt %. At 360 °C, 77.3 % of the maximum hydrogen capacity could be absorbed within 2 min, while only 1.4 min was required to release 3 % of hydrogen. Additionally, Eu2O3@C markedly decreased the dehydrogenation activation energy of the alloys to 106.3 kJ/mol and reduced the endothermic peak temperature to 347 °C, while leaving thermodynamic properties unaffected. The Mg96La3Ni–Eu2O3@C composite exhibits remarkable cyclic stability, retaining its hydrogen storage capacity throughout the cycling process. This study pioneers a novel strategy to elevate the performance of magnesium-based hydrogen storage materials.

A Comparative Analysis of Hydrogen Storage Characteristics in AZ31 Magnesium Alloy with the Addition of Graphene and Carbon Nanotubes via Ball Milling Process

In the present investigation, an examination was conducted on the hydrogen storage performance of industrial waste grade AZ31 magnesium alloy when combined with either Carbon Nanotubes or Graphene. This study aims to understand the enhancement of hydrogen storage properties reinforced with polymer materials, such as Graphene or Carbon Nanotubes. The experimental samples, composed of AZ31 Magnesium Alloy combined with either Carbon Nanotubes or Graphene, were crafted through gravity casting. Thereafter, a high-energy ball milling process was employed to further refine the hydrogen storage material powders. The micrographic structures of all the sample powders were analyzed by x-ray diffraction (XRD), and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Additionally, the average particle size distributions of the sample powders were quantified for comprehensive characterization. The absorbed and desorbed hydrogen capacity and kinetics was calculated by a Sievert's type apparatus. Overall, the performance of the sample powder AZ31-0.1G showed the highest absorption and desorption at a rate of 0.0036 wt%/s and 0.0084 wt%/s. Moreover, the hydrogen capacity of AZ31-0.1G reached the highest value at 5.32 wt%. The acquired data unveils that with the adding of either Graphene or Carbon Nanotubes as additives significantly improved the hydrogen storage capacity of AZ31 magnesium alloy.

Hydrothermal architecture of Bi0.48Tb1.52Ti2O7/polyaniline nanocomposites to improve electrochemical hydrogen storage performance

Today, with the emergence of new technologies and the expansion of renewable energy infrastructure such as hydrogen, the discussion of energy security and the promotion of active materials for advanced hydrogen storage has an important place. For this purpose, in this research, an important strategy was designed to develop the electrochemical performance of electroactive materials Bi0.48Tb1.52Ti2O7 (BTTO) nanostructure was prepared through a hydrothermal route in the presence of fructose as a biotemplate agent. To achieve the desired chemical composition and to optimize the size and morphology, the reaction temperature was changed. The effect of polyaniline conductive polymer to improve hydrogen storage capacity was studied by introducing two composites. The structural characteristics, dimensions, and porosity of the products were investigated through Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), field emission scanning electron microscope (FE-SEM), high-resolution transmission electron microscope (HR-TEM) and Brunauer-Emmett-Teller (BET). In the following, the potential of pristine Bi0.48Tb1.52Ti2O7 nanoparticles and Bi0.48Tb1.52Ti2O7/Polyaniline (BTTO/PANI) nanocomposites in the direction of hydrogen storage were evaluated through CV, EIS and CP techniques. BTTO/PANI nanocomposites showed a discharge capacity of 1223 mAhg−1 after 15 cycles. This study showed the potential effect of PANI in terms of improving conductivity and providing more charge transfer channels for hydrogen transfer.

Improved hydrogen storage kinetics of MgH2 using TiFe0.92Mn0.04Co0.04 with in-situ generated α-Fe as catalyst

While TiFe alloy has recently attracted attention as the efficient catalyst to enhance de/hydrogenation rates of Mg/MgH2, the difficulty of its activation characteristics has hindered further improvement of reaction kinetics. Herein, we report that the TiFe0.92Mn0.04Co0.04 catalyst can overcome the abovementioned challenges. The synthesized MgH2-30 wt% TiFe0.92Mn0.04Co0.04 can release 4.5 wt% of hydrogen in 16 min at 250 °C, three times as fast as MgH2. The activation energy of dehydrogenation was as low as 84.6 kJ mol−1, which is 46.8% reduced from pure MgH2. No clear degradation of reaction rates and hydrogen storage capacity was observed for at least 30 cycles. Structural studies reveal that TiFe0.92Mn0.04Co0.04 partially decomposes to in-situ generated α-Fe particles dispersed on TiFe0.92Mn0.04Co0.04. The presence of α-Fe reduces the formation of an oxide layer on TiFe0.92Mn0.04Co0.04, enabling the activation processes. At the same time, the hydrogen incorporation capabilities of TiFe0.92Mn0.04Co0.04 can provide more hydrogen diffusion paths, which promote hydrogen dissociation and diffusion. These discoveries demonstrate the advanced nature and importance of combining the in-situ generated α-Fe with TiFe0.92Mn0.04Co0.04. It provides a new strategy for designing highly efficient and stable catalysts for Mg-based hydrogen storage materials.

Effect of industrial grade raw materials and its associated impurities on first hydrogenation of BCC solid solution alloys

This study explores the effects of using industrial-grade raw materials on the hydrogen storage properties of body-centered cubic (BCC) solid solution alloys. Industrial scrap metals were chosen as the raw material, and the desired alloys were synthesized using a vacuum arc melting furnace. Instead of using pure vanadium (V), different inexpensive industrial substitutes such as low-grade vanadium (V), vanadium nitride (VN), vanadium oxide (VO), and ferrovanadium (FeV) were utilized. The crystal structure, morphology, first hydrogenation, thermodynamics, and cyclability of the prepared alloys were analyzed by using XRD, SEM-EDS, and XPS methods. The crystal structure and morphology analysis revealed multiphase alloys in all the prepared alloys and a Ti rich third phase in the VN sample, which was absent otherwise. The first hydrogenation was performed at room temperature under a hydrogen pressure of 2 MPa without any prior heat treatment. The VO alloy displayed negligible hydrogen absorption during first hydrogenation, while the V, VN, and FeV alloys showed maximum hydrogen storage capacities of 3.49 wt%, 2.47 wt%, and 2.18 wt%, respectively. The presence of oxygen hinders the activation of the VO alloy and requires two activation cycles to activate the sample. A short-term cyclability analysis showed a reversible hydrogen storage capacity of 2 wt%. The change in enthalpy of hydrogen absorption and desorption for V alloy were calculated to be −36.73 ± 8.6 and 57.34 ± 8.3 kJ/mol H2, respectively. One of the prominent advantages of utilizing scrap raw materials was the substantial reduction in overall raw material costs, which saw an impressive 95% decrease when compared to using pure raw materials. These results highlight the economic benefits of incorporating recovered industrial scrap into hydrogen storage alloys.

Optimization Strategy in Hydrogen Storage Performance of Ti─V─Cr─Mn Alloys via LiAlH4.

V-based solid solution materials hold a significant position in the realm of hydrogen storage materials because of its high hydrogen storage capacity. However, the current dehydrogenation temperature of V-based solid solution exceeds 350°C, making it challenging to fulfill the appliance under moderate conditions. Here advancements in the hydrogen storage properties and related mechanisms of TiV1.1Cr0.3Mn0.6+x LiAlH4 (x=0, 5, 8, 10wt.%) composites is presented. According to the first principle calculation analysis, the inclusion of Al and Li atoms will lower the binding energy of hydride, thus enhancing the hydrogen absorption reaction and significantly decreasing the activation difficulty. Furthermore, based on crystal orbital Hamilton population (COHP) analysis, the strength of the V─H and Ti─H bonds after doping LiAlH4 are reduced, leading to a decrease of the hydrogen release activation energy (Ea) for the V-based solid solution material, thus the hydrogen release process is easier to carry out. Additionally, the structure of doped LiAlH4 exhibits an outstanding hydrogen release rate of 2.001wt.% at 323K and remarkable cycling stability.

Synthesis of sulfur-encapsulated mullite structure Bi0/Fe0-Rich Bi2Fe4O9−x framework by advanced probe sonic approach applied for augmented electroactive hydrogen production, storage and photoactive degradation studies

A new series of dual Bi0/Fe0-rich in sulfur-encapsulated BFNPs (SBFNPs-framework) with a sulfur content ranging from 1.0% to 3.0% were prepared using an advanced probe-sonic approach. The SBFNPs-framework with a sulfur content of 2.0% exhibited a maximum methylene-blue (MB) photo-degradability of 84.20% at 120 min of visible-light exposure. The MB degradation rate of the SBFNPs-framework (0.00839 min−1) was faster than that of pure-BFNPs (0.00308 min−1). Furthermore, the electro-catalyst of SBFNPs-framework demonstrated remarkable hydrogen-production activity, as indicated by a low over-potential (204 mV), a small Tafel-slope (69 mV/dec), a higher double-layer-capacitance (142.0 mF/cm2), a larger electro-chemically-active-surface-area (40.6 cm2), a plentiful presence of catalytic-active-sites (5.65 ×10−7 mol/cm2), and excellent stability, respectively. Also, the hydrogen-storage capacity of the SBFNPs-framework exhibited a maximum discharge capacity of 717.35 mAhg−1 and a hydrogen-storage capacity of 2.66 wt% at a 2.0% sulfur content. These findings have great potential implications for future energy storage and environmental applications.

Enhanced room-temperature hydrogen storage by CuNi nanoparticles decorated in metal-organic framework UiO-66(Zr)

This study demonstrates the significant effect of incorporating inexpensive transition metal nanoparticles into metal-organic frameworks (MOFs) to improve their room-temperature hydrogen storage properties. Low-cost nanoparticles (Cu, Ni, and CuNi) were incorporated into UiO-66(Zr) via the double-solvent approach (DSA) plus chemical reduction processes. All composites exhibited higher hydrogen storage capacity compared to pure UiO-66 at both room temperature and 60 bar. Notably, the hydrogen spillover efficiency of CuNi nanoparticles loaded in UiO-66 was comparable to that of MOF adsorbents embedded with noble metals such as Pd and Pt. The hydrogen storage capacity of CuNi@UiO-66 was significantly increased from 0.20 wt% to 0.74 wt%. DFT calculations showed that the CuNi alloys facilitated the adsorption and dissociation of hydrogen molecules in comparison to the single metal nanoparticles, thus favoring the hydrogen spillover effect and improving the hydrogen storage performance. This work demonstrates the potential of designing MOF loaded with inexpensive metal nanoparticles for optimized room-temperature hydrogen storage.

Low-Voltage Hydrogen Production via Hydrogen Peroxide Oxidation Facilitated by Oxo Ligand Axially Coordinated to Cobalt in Phthalocyanine Moiety

The global energy sector is shifting from fossil-based systems of energy production and consumption to renewable-based ones like wind and solar energy. Hydrogen has emerged as one of the energy carriers for the renewable-based economy, storing electrical energy generated from the renewables and being used as a fuel to generate power. Water electrolysis, powered by renewable energies, is one of the most feasible green hydrogen production technologies. At least 1.23 V and typically > 2 V is required between hydrogen and oxygen evolution reactions (HER and OER) for splitting water. OER is notorious for its slow kinetics so that the OER determines hydrogen production rate. Therefore, it has been emphasized to develop high-performance and low-cost OER electrocatalysts for reducing overpotentials required for electrolyzing water. Even if up-to-date upgraded electrocatalysts have decreased the kinetic overpotentials, it is clearly evident that it is impossible to split water molecules at the cell voltage less than 1.23 V. To decrease the potential required for water electrolysis, water oxidation reaction to drive OER was suggested to be replaced by oxidation of organic molecules or nitrogen hydrides such as formic acid and hydrazine. However, even if the more negative E o of the organic molecules allowed the open-circuit potential difference between cathodic and anodic processes to be reduced, it sounds self-contradictory to employ carbon-based organic molecules and therefore produce carbon dioxide for producing green hydrogen.Suggesting hydrogen peroxide as an electrolysis medium for hydrogen production and therefore as a hydrogen carrier, in this work, we present a cobalt phthalocyanine having electron-poor CoN4 (+δ) in its phthalocyanine moiety as an electrocatalyst for hydrogen peroxide oxidation reaction (HPOR), demonstrating that the electrocatalyst guaranteed high hydrogen production rate by hydrogen peroxide splitting. The electron deficiency of cobalt allowed CoN4 to have the highly HPOR-active monovalent oxidation state and facilitate HPOR at small overpotentials range around the onset potential. The strong interaction between the electron-deficient cobalt and oxygen of peroxide adsorbates in Co-OOH- encouraged an axially coordinated cobalt oxo complex (O=CoN4) to form, the O=CoN4 facilitating the HPOR efficiently at high overpotentials. Low-voltage oxygen evolution reaction (OER) guaranteeing low-voltage hydrogen production was successfully demonstrated in the presence of the metal-oxo complex having electron-deficient CoN4. Hydrogen production by 391 mA cm-2 at 1 V and 870 mA cm-2 at 1.5 V was obtained.Also, we evaluated the techno-economic benefit of hydrogen peroxide as a hydrogen carrier by comparing hydrogen peroxide with other hydrogen carriers. Here, even though water (H2O) can be considered as a carrier, about 61 kWh/kg of energy is required for converting transported H2O to H2 again. Thus, in this case, if renewable energy can be supplied from the demand site, H2 can be produced directly on-site from the demand site without having to transport the H2 produced from another renewable energy complex. If renewable power cannot be supplied from the demand site, all the required energy for water electrolysis should be supplied with existing fossil fuel-based energy, it is like losing the eco-friendly significance of H2 energy, and considering energy consumption, using other carriers will be more economical and environmental. In this situation, H2O2 can act as a hydrogen carrier as a hydrogen/oxygen simultaneous receptor. When generated hydrogen is stored and transported, high cost arises. To lower the cost, many countries are paying attention to LOHC (=liquid organic hydrogen carrier) and ammonia which are materials to storage hydrogen energy. For LOHC, methylcyclohexane 6.1 wt.% and 47 kg H2/m3, dibenzyltoluene 6.2 wt.% and 57 kg H2/m3, ethylcarbazole 5.8 wt. % and 57 kg H2/m3, with a hydrogen storage capacity of 47 - 57 kg H2/m3. For ammonia, it has a hydrogen storage capacity of 17.6 wt. %, and 108 kg H2/m3. In the case of H2O2, it has 5.9 wt.% and 85.3 kg H2/m3, which belongs to the high hydrogen storage capacity compared to other hydrogen storage materials. To evaluate the economic analysis, we conducted to identify that H2O2 can be utilized for green H2 supply by comparing diverse hydrogen storage and transportation pathways. Furthermore, the scenario analysis was performed for CGH2, LH2, NH3, toluene-based LOHC, and H2O2. Figure 1

(Digital Presentation) Designing New Complex Hydrides Based on Transition Metals for Hydrogen Storage Applications

The widespread implementation of the hydrogen economy demands access to materials with a high weight percentage of hydrogen. Mg-based hydrogen storage alloys have become a research hot-spot in recent years owing to their high hydrogen storage capacity, good reversibility of hydrogen absorption/desorption, low cost, and abundant resources. However, high decomposition temperature of Mg-based hydrideslimits their practical usage. Hydrogen is lightest of all elements, typically it need large volumes or high pressures to store appreciable amount of hydrogen.To overcome these challenges research activities are currently going on metal hydrides and complex hydrides based on transition metal. The main challenges come when endothermic decomposition enthalpy is considered. It becomes difficult to release the hydrogen at ambient thermodynamic conditions. On the other hand, the meta-stable hydrides are characterized by a low reaction enthalpy and a decomposition reaction that is thermodynamically favourable under the ambient conditions. The good kinetics along with evolution of hydrogen around the room temperature possessed by these materials offer much promise for underground storage and it can be used as a grid energy.The present research specifically focus on transition metal based complex hydrides such as NaMgMnH6 and NaMgFeH6 for hydrogen storage and especially predicted the crystal structure of the same using VASP simulation package. ABCX6 and AB2X6 were taken as reference composition A,B,C and X were substituted with Na, Mg, transition metals(Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu) and H, respectively.From the ICSD database search the corresponding structural variants were considered as trial structure to predict the ground state structure of these newly designed compounds. using the predicted ground state structure for these compounds, important properties like formation energy, hydrogen site energy, partial density of states(pDOS), electron density(ED), Mulliken effective charge(MEC), Bader electron charge(BEC), Born effective charge, ELF and COHP were calculated. the calculated properties of these compounds were compared with the well known reference compounds. We found that both NaMgMnH6 and NaMgFeH6 are stable with negative formation energy and als othey are semiconductors with the band gap value of 0.51eV and 1.01 eV, respectively. from the calculated electronic structure we found that both these materials are having indirect band behaviour. Analysing the electronic density of states, charge density and various charges mentioned above the chemical bonding behaviour was established as iono-covalent in nature. from the force as well as stress minimisation considering 53 structural variants as input the ground state structure, its space group, equilibrium lattice parameters and atom positions are listed. Also from the energy vs. volume curve for the ground state structure, the equilibrium volume, bulk modulus and pressure derivatives were found out. Among NaMgMnH6 and NaMgFeH6 our spin polarised calculation show that NaMgMnH6 is possesing spontaneous magnetic polarisation with substantial magnetic moment at the Mn site. Among the considered paramagnetic, ferromagnetic, as well as A-, C-,and G- antiferromagnetic configurations the G type antiferromagnetic configuration is found to be the ground state for NaMgMnH6.

A DFT investigation of Osmium decorated single walled carbon nanotubes for hydrogen storage

The investigation for hydrogen storage in armchair single walled carbon nanotubes (SWCNTs) with decoration of osmium atom on the surface of tube has been done using ab-initio method utilizing Density Functional Theory (DFT). In the present work, single/dual osmium atoms decoration on the surface of SWCNTs (5,5) has been investigated regarding the effects on structural, electronic and thermodynamic properties. Frontier molecular orbital (FMO) i.e. HOMO and LUMO structures and electrostatic potential surfaces (ESP) of all geometrically optimized and stable species are studied. Investigations regarding metal-metal clustering are carried out by calculating diffusion barrier energy for osmium atoms and atomistic molecular dynamic simulations performed at 300°K temperature for 1ps. It is found that osmium decoration on SWCNTs enhances the hydrogen storage capacity via spillover mechanism. It is observed that the adsorption energy per hydrogen molecule in case of Pristine SWCNT is -0.001eV, which is increased with decoration of osmium atoms and finally found to be -0.575eV/H2 in case of single osmium decorated SWCNT (Os-CNT) and -0.681eV/H2 due to double osmium decoration on SWCNT (2Os-CNT). This study reveals gravimetric hydrogen storage capacity of 1.32 wt% and 2.53 wt% for Os-CNT and 2Os-CNT respectively at 298.15 K temperature and 10 atm pressure. Average Van't Hoff desorption temperature for osmium decorated SWCNTs are also calculated.

Controllable Electrochemical Liberation of Hydrogen from Sodium Borohydride.

Sodium borohydride (NaBH4 ) has earned recognition as a promising hydrogen carrier, attributed to its exceptional hydrogen storage capacity, boasting a high theoretical storage capacity of 10.8 wt %. Nonetheless, the utilization of traditional pyrolysis and hydrolysis methods still presents a formidable challenge in achieving controlled hydrogen generation especially under ambient conditions. In this work, we report an innovative electrochemical strategy for production H2 by coupling NaBH4 electrooxidation reaction (BOR) at anode in alkaline media with hydrogen evolution reaction (HER) at cathode in acidic media. To implement this, we have developed a bifunctional electrocatalyst denoted as Pd-Mo2 C@CNTs, wherein Pd nanoparticles are grown in situ on Mo2 C embedded within N-doped carbon nanotubes. This electrocatalyst demonstrates exceptional performance in catalyzing both alkaline BOR and acidic HER. We have developed a hybrid acid/alkali cell, utilizing Pd/Mo2 C@CNTs as the anode and cathode electrocatalysts. This configuration showcases remarkable capabilities for self-sustained, precise, and uninterrupted indirect release of H2 stored in NaBH4 , even at high current densities of 100 mA cm-2 with a Faraday efficiency approaching 100 %. Additionally, this electrochemical device exhibits significant promise as a fuel cell, with the ability to deliver a maximum power density of 20 mW cm-2 .

Controllable Electrochemical Liberation of Hydrogen from Sodium Borohydride

AbstractSodium borohydride (NaBH4) has earned recognition as a promising hydrogen carrier, attributed to its exceptional hydrogen storage capacity, boasting a high theoretical storage capacity of 10.8 wt %. Nonetheless, the utilization of traditional pyrolysis and hydrolysis methods still presents a formidable challenge in achieving controlled hydrogen generation especially under ambient conditions. In this work, we report an innovative electrochemical strategy for production H2 by coupling NaBH4 electrooxidation reaction (BOR) at anode in alkaline media with hydrogen evolution reaction (HER) at cathode in acidic media. To implement this, we have developed a bifunctional electrocatalyst denoted as Pd‐Mo2C@CNTs, wherein Pd nanoparticles are grown in situ on Mo2C embedded within N‐doped carbon nanotubes. This electrocatalyst demonstrates exceptional performance in catalyzing both alkaline BOR and acidic HER. We have developed a hybrid acid/alkali cell, utilizing Pd/Mo2C@CNTs as the anode and cathode electrocatalysts. This configuration showcases remarkable capabilities for self‐sustained, precise, and uninterrupted indirect release of H2 stored in NaBH4, even at high current densities of 100 mA cm−2 with a Faraday efficiency approaching 100 %. Additionally, this electrochemical device exhibits significant promise as a fuel cell, with the ability to deliver a maximum power density of 20 mW cm−2.

Stoichiometry and annealing condition on hydrogen capacity of TiCr2-x AB2 alloys

This study presents the effect of stoichiometry and annealing condition on Ti–Cr AB2-type hydrogen storage alloys. Prior to annealing the majority phase of the as-cast alloys was the C14 Laves phase, with separate Ti and Cr phases. Annealing treatment (1273 K/14 d) led to a transition from C14 to C15 Laves phase structure. Both C14 (as-cast) and C15 (annealed) cell size increased with Ti content, up to a ratio (Cr/Ti) of 1.6, due to B-site Ti substitution in the lattice up to a limit. Pressure composition isotherm (PCI) measurements demonstrated alloys containing a greater Ti content had a better maximum hydrogen storage capacity (1.5 vs. 1.03 wt%) and lower plateau pressure (9.4 vs. 15.8 bar) at 253 K. Annealing resulted in a lower storage capacity (1.05 vs. 1.49 wt%), greater plateau pressure (ca. 30 bar) and flatter plateau slope (25 % reduction in plateau slope). Reduction in hydrogen storage capacity of annealed alloys could be due to diffusion of residual Cr in the alloy into the C15 Laves phase during the annealing process, thereby changing the local composition as confirmed through X-ray diffraction (XRD).

Microstructure and hydrogen storage properties of Ti1-xCexV0.45Mn1.5 (x = 0, 0.05, 0.10, 0.15, and 0.20) alloys

In this work, the microstructure and hydrogen storage properties of Ti1-xCexV0.45Mn1.5 (x = 0, 0.05, 0.10, 0.15, and 0.20) alloys have been studied. It shows that the x = 0 alloy consists of a C14 Laves single phase. Moreover, alloys containing Ce can exhibit the CeO2 phase, whose content rises as Ce content does. Furthermore, CeO2 phase aggregation causes the alloy to fracture and the hydrogen diffusion channel to enlarge. According to the PCT curves (25 °C), the plateau pressure increases with increasing Ce content, and the hydrogen storage capacity decreases with increasing Ce content due to increase in Ce content which does not absorb hydrogen. And it is also found that increase in Ce substitution for Ti results in better dynamic properties for the alloys. And the dehydrogenation kinetics curves show that hydrogen desorption rate substantially increases with x getting larger. This is because CeO2 phase acts as the "hydrogen pump" to increase the rate of hydrogen discharge in the alloy, The fastest hydrogenation kinetics are shown, the best hydrogen storage performance is achieved, and the maximum hydrogenation is reached in less than 100 s.

Microstructure and gas-solid hydrogen storage properties of La1-xCexY2Ni10.95Mn0.45 (x = 0 – 0.75) alloys

RE-Y-Ni-based superlattice alloys have been studied for their high hydrogen storage capacity and excellent activation properties. However, their practical applications in gas-solid hydrogen storage devices are limited by their low hydrogen absorption/desorption platform pressure and the occurrence of a double platform phenomenon. In this study, we investigated the phase structure and gas-solid hydrogen storage properties of La1−xCexY2Ni10.95Mn0.45 (x = 0, 0.15, 0.30, 0.45, 0.60, 0.75) alloys. As the Ce content increases, the content of Ce2Ni7 phase and the platform pressure also increase, while the hydrogen storage capacity and hydrogen desorption enthalpy decrease. When the Ce content increases to 0.45, the Gd2Co7 phase disappears and the LaNi5 phase appears, the hydrogen absorption/desorption platform of the alloy changes from a double platform to a single platform. However, the increase in Ce content leads to a higher amount of residual hydrogen during the dehydrogenation process, attributed to the increased content of the Ce2Ni7 phase. The La0.55Ce0.45Y2Ni10.95Mn0.45 alloy exhibits a hydrogen absorption capacity of 1.61 wt%, with a capacity retention of 97.89% after 100 cycles, and achieves a hydrogen desorption platform pressure of 0.23 MPa. These results indicate that this alloy demonstrates the best overall hydrogen storage performance, characterized by high platform pressure and hydrogen storage capacity.

Reversible hydrogen storage in Li-functionalized [1,1,1,1]paracyclophane: A computational insight

This study focuses on investigating the hydrogen adsorption-desorption properties and storage capacities of Li functionalized [1,1,1,1]paracyclophane (PCP1111) using dispersion-corrected density functional theory and molecular dynamics simulation. The Li atom is bound to the [1,1,1,1]paracyclophane's benzene ring via Dewar mechanism, with a binding energy of 0.32 eV without any clustering. Each Li atom is found to adsorb 5H2 molecules, causing the host material PCP1111–4Li to adsorb up to 20H2 molecules via charge polarization with an average adsorption energy of 0.156 eV/H2, indicating physisorption type adsorption. The charge polarization during hydrogen adsorption is studied using Hirshfeld charge analysis and electrostatic potential maps. PCP1111–4Li saturated with 20H2 results in gravimetric densities as high as 9.4 wt%, which is considerably higher than the US-DOE target. During the H2 adsorption process, the host material's geometry does not change significantly, indicating its chemical stability. When the temperature exceeds 180 K under 30–60 bar, the gravimetric density decreases, but it is still greater than 5.5 wt%, which is the target set by the US Department of Energy for 2025. The maximum H2desorption temperature estimated by the Vant-Hoff relation is found to be 216 K and 266 K at 1 atm and 5 atm, respectively. ADMP molecular dynamics shows the structural integrity and reversibility of host materials.

First-principles investigation for the hydrogen storage properties of AeSiH3 (Ae = Li, K, Na, Mg) perovskite-type hydrides

The present study investigates the physical properties of AeSiH3 (Ae = Li, K, Na, Mg) hydrides perovskites with their hydrogen storage capability. All the materials are thermally, dynamically, and mechanically stable. The lattice constants are 4.001, 3.917, 3.986, and 3.977 Å for LiSiH3, KSiH3, NaSiH3, and MgSiH3, respectively. The gravimetric ratio for hydrogen storage capacity is 7.946, 4.306, 5.588, and 5.456 wt% for LiSiH3, KSiH3, NaSiH3, and MgSiH3, respectively. All the materials have zero bandgap and possess a brittle nature with ionic bonding. Elastic constants were used to determine the mechanical properties like bulk modulus, shear modulus, Young's modulus, and Poisson's ratio. The thermodynamic parameters such as Debye temperature and melting temperature are also calculated and discussed in detail using the elastic constants. These calculated properties suggest that AeSiH3 (Ae = Li, K, Na, Mg) hydride perovskites are potential candidates for hydrogen storage applications.

Investigating surface area and hydrogen pressure effects on LiH and NaH

NaH and LiH are theoretically capable of storing hydrogen, but several challenges remain to be overcome before they can be widely used for hydrogen storage. In this study, LiH and NaH were ball-milled and the effect of surface area and hydrogen pressure on hydrogen storage capacity was investigated using the solid-state hydrogen storage method. XRD patterns and Raman spectra show significant shifts in main peak positions of LiH and NaH after hydrogen adsorption. BET analysis shows a significant increase in the specific surface area of LiH and NaH from 6.25 m2/g to 12.35 m2/g and from 1.34 m2/g to 2.33 m2/g respectively due to ball milling. The FTIR spectra showed more bonds in the 400–1200 cm⁻1 fingerprint region after storing hydrogen in LiH and NaH. This suggests structural changes with enhanced bond bending due to hydrogen. At 9 bar pressure, LiH and NaH exhibited excellent hydrogen storage, with ball-milled LiH reaching about 3.55 wt% and 652 sccm, and NaH achieving approximately 1.58 wt% and 291 sccm. These results highlight the significant influence of surface area and hydrogen pressure on hydrogen storage potential. Incorporating the storage potential within the evaluation of PEM fuel cell performance, we suggest that an increased storage capacity directly corresponds to an augmented power density. The analysis of power density over time revealed that the hydrogen adsorbed ball-milled LiH exhibited the highest power density, peaking at 0.075 Wcm−2 over the long term. In contrast, LiH displayed a lower power density (0.025 Wcm−2) while maintaining its long-term performance. The hydrogen adsorbed NaH and hydrogen adsorbed ball-milled NaH displayed power densities 0.050 Wcm−2 and 0.073 Wcm−2, respectively, but they showed short-term performance.