High-capacity Hydrogen Storage Materials Research Articles

Effect of Cr/Mn Addition in TiVNb on Hydrogen Sorption Properties: Thermodynamics and Phase Transition Study

High-entropy alloys (HEAs) are a promising class of materials that can grant remarkable functional performances for a large range of applications due to their highly tunable composition. Among these applications, recently, bcc HEAs capable of forming fcc hydrides have been proposed as high-capacity hydrogen storage materials with improved thermodynamics compared to classical metal hydrides. In this context, a single-phase bcc (TiVNb)0.90Cr0.05Mn0.05 HEA was prepared by arc melting to evaluate the effect of combined Cr/Mn addition in the ternary TiVNb. A thermodynamic destabilization of the fcc hydride phase was found in the HEA compared to the initial TiVNb. In situ neutron and synchrotron X-ray diffraction experiments put forward a fcc → bcc phase transition of the metallic subnetwork in the temperature range of 260–350 °C, whereas the H/D subnetwork underwent an order → disorder transition at 180 °C. The absorption/desorption cycling demonstrated very fast absorption kinetics at room temperature in less than 1 min with a remarkable total capacity (2.8 wt.%) without phase segregation. Therefore, the design strategy consisting of small additions of non-hydride-forming elements into refractory HEAs allows for materials with promising properties for solid-state hydrogen storage to be obtained.

Hydrogen Fuel Cell Integration: Automotive, Residential Power Generation & Portable Devices

Hydrogen fuel has emerged as a promising element in the quest for sustainable energy solutions across diverse sectors. This abstract distils the findings and insights from extensive research into hydrogen fuel integration, focusing on its applications in the automotive industry, residential power generation, and portable devices. In the automotive sector, hydrogen fuel cell vehicles (FCVs) offer a zero-emission alternative with extended driving ranges and rapid refuelling times, addressing some of the limitations of battery electric vehicles (BEVs). However, the successful integration of hydrogen as a transportation fuel hinges on the development of a robust refuelling infrastructure, cost reductions in fuel cell technology, and the optimization of energy-intensive hydrogen production processes. In residential power generation, hydrogen shows promise as a versatile energy carrier, capable of powering homes through fuel cells or combined heat and power (CHP) systems. To ensure sustainable residential hydrogen power, research efforts should continue to focus on efficient hydrogen production methods, such as advanced electrolysis powered by renewable energy sources. Furthermore, the integration of hydrogen in portable devices, including backup power systems and mobile electronics, is being explored. Overcoming challenges related to safe hydrogen storage, efficient energy conversion, and addressing energy density limitations are critical for expanding the utility of hydrogen in this domain. To drive further advancements, key research directions include the development of lightweight and high-capacity hydrogen storage materials, improvements in energy conversion efficiency, and enhanced safety measures for hydrogen-powered portable devices. Moreover, cross-sector collaboration between automotive, residential, and portable device applications is vital to optimize hydrogen production and utilization. Regulatory support and incentives play a pivotal role in promoting the adoption of hydrogen technologies, along with comprehensive life-cycle assessments to quantify their environmental impact.

Effect of Ti0.9Zr0.1Mn1.5V0.3 alloy catalyst on hydrogen storage kinetics and cycling stability of magnesium hydride

As a high-capacity hydrogen storage material, MgH2 still has the problem of high operating temperature and slow reaction kinetics. In this work, an TiMn2-based Laves phase alloy (Ti0.9Zr0.1Mn1.5V0.3, denoted as Ti–Mn) was first synthesized by arc melting and then employed to regulate the hydrogen storage properties of MgH2, with the carbon nanotubes (CNTs) as an aid agent to facilitate the hydrogen diffusion and heat transfer. It was shown that the introduction of Ti–Mn/CNTs can remarkably improve the hydrogen storage properties of MgH2. The MgH2 + 10 wt% Ti–Mn + 1 wt% CNTs composite has an initial dehydrogenation temperature of 195 °C and can absorb hydrogen at room temperature. As for the kinetics, it can release 6.1 wt% H2 in 5 min at 300 °C, and absorb 4.8 wt% H2 in 10 min at 150 °C. It still has a reversible capacity of 6.2 wt% after 100 cycles. Combination of Ti–Mn alloy and CNTs is more effective than Ti–Mn alloy or CNTs alone for regulating MgH2. Ti–Mn/CNTs does not alter the overall thermodynamics of MgH2. However, local destabilization of Mg–H bonds induced by the MgH2/Ti–Mn interfaces was observed experimentally and confirmed theoretically, which partially contributes to the enhanced hydrogen storage of MgH2. In addition, the active transition metals contained in the alloy was believed to accelerate the hydrogen dissociation and delivery during the hydrogen storage process. This work not only achieves the synergistic improvement of hydrogen storage of MgH2 by combination of Ti–Mn alloy and CNTs, but also presents the local destabilization mechanism to explain the improved hydrogen storage of MgH2 by Ti–Mn alloy experimentally and theoretically.

Hydrogen storage on the lithium and sodium-decorated inorganic graphenylene

Efficient H2 storage is one of the keys to the energy transition toward global sustainability. Hydrogen energy sources on functionalized 2D materials by metals have been shown as promising alternatives for clean energy systems. In a particular way, we have demonstrated here that the inorganic graphenylene-like silicon carbide (IGP-SiC) weakly adsorbs H2. At the same time, the Li/Na decoration significantly enhances the H2 interaction, accommodating up to 48H2 molecules by a stronger physisorption. Also, scanning bond critical points (BCPs) confirms a great interaction between the Li(Na)@IGP-SiC systems and the hydrogen, a distinct scenario for the pristine IGP-SiC. Gravimetrically, hydrogen densities reach 8.27 wt% (Li) and 6.78 wt% (Na), exceeding the U.S. Department of Energy (5.6 wt%) benchmark. Regarding thermodynamic stability, the desorption temperatures at ambient conditions are suitable for hydrogen storage devices. Therefore, Li(Na)@IGP-SiC systems emerge as high-capacity hydrogen storage materials.

Local structural changes in V–Ti–Cr alloy hydrides with hydrogen absorption/desorption cycling

Vanadium-based solid solution alloys potentially serve as safe, high-capacity hydrogen storage materials. Low-vanadium-concentration alloys have low durability, and their hydrogen absorption and desorption amounts decrease by 20 % after 100 cycles. In this study, we conducted reverse Monte Carlo modeling on X-ray diffraction patterns and neutron pair distribution functions of the hydrogen-absorbed and desorbed samples of a V0.10Ti0.36Cr0.54 alloy to analyze the variations in the local structure. The local structure surrounding the hydrogen atom in the hydrogen-absorbed phase exhibited minimal changes. In contrast, hydrogen occupied both tetrahedral and octahedral sites of the hydrogen-desorbed phase almost equally during the early cycles; however, the amount of hydrogen occupying the tetrahedral sites increased with the number of cycles. It is speculated that hydrogen absorption and desorption cycling induced grain refinement and/or introduced dislocations, which altered both the amount of hydrogen and the sites occupied in the desorbed phase, thereby decreasing the hydrogen storage capacity.

Experimental investigation on the explosion characteristics and flame propagation behavior of aluminum hydride dust

Aluminum hydride (AlH3) dust is a high-capacity hydrogen storage material but is prone to explosion. In this paper, explosion characteristics and flame propagation behavior of AlH3 dust are investigated. The results indicate that the exposure of bare aluminum and the increase of specific surface area lead to the maximum explosion pressure of AlH3 dust being 4 times higher than that of Al dust. The enhancement of heat transfer by hydrogen combustion causes a higher combustion rate, leading to a higher maximum explosion pressure rise rate and flame propagation velocity of AlH3 dust. The thermo-diffusive instabilities and the evolution of hydrogen result in a pulsation flame propagation velocity of AlH3 dust. Combining the explosion temperature calculated by NASA CEA with the explosion residues analysis, the explosion mechanism of AlH3 dust is further revealed. The break of the oxide film and the combustion of hydrogen result in a different explosion mechanism.

Crucial role of Mg on phase transformation and stability of Sm–Mg–Ni-based AB2 type hydrogen storage alloy

Rare earth–Mg–Ni-based alloys are promising candidate for high-capacity hydrogen storage materials, and Mg is the key elements to maintain its crystal structure stable. In order to understand the role of Mg element in rare earth–Mg–Ni based alloys, the alloys with the composition of RE1–xMgxNi1.97Co0.03Al0.07 (RE = Sm0.80Y0.20; x = 0.35, 0.44, 0.52) were synthesized by powder sintering treatment. The increasing Mg content promotes the phase transformation from SmNi2 (Fd-3 m group) phase to MgCu4Sn-type (F-43 m group) phase. First-principle calculations and XRD simulations show that Mg element is reasonably approximated as the para-position substitution of rare earth elements at 4c sites when it enters into the unit cell of SmNi2 phase. The Sm0.38Y0.10Mg0.52Ni1.93Co0.03Al0.05 alloy with Mg fully occupying the 4c sites forms a stable structure, and it shows flat hydrogen absorption/desorption platforms, with a hydrogen absorption capacity of 1.12 wt%. Meanwhile, it has more excellent cycling stability. After 20 cycles of hydrogen absorption, the crystal structure of the alloy still maintains MgCu4Sn-type phase, and the capacity retention rate can reach 94.42 %.

Improved hydrogen storage properties of MgH2 by Mxene (Ti3C2) supported MnO2

MgH2 is a promising high-capacity solid hydrogen storage material. In this work, MnO2-doped Ti3C2 (Ti3C2@MnO2) was synthesized and used as a catalyst to improve the hydrogen storage performance of MgH2. We found that the dehydrogenated 10 wt% Ti3C2@MnO2-doped MgH2 sample exhibited good hydrogen adsorption ability even at room temperature (30 °C), and could absorb 5.13 wt% of hydrogen in 400 s at 75 °C. The re‑hydrogenated Ti3C2@MnO2-doped MgH2 sample started to release hydrogen at 182 °C and required 484 s to completely release hydrogen at 275 °C with a dehydrogenation capacity of 6.4 wt%. The Ti3C2@MnO2 composite did not change the thermodynamic properties of MgH2. In the MgH2 + Ti3C2@MnO2 sample, Ti3C2, TiO2, MnO2, MnO, and Mn combined with MgH2 to form Ti3C2/MgH2, TiO2/MgH2, MnO2/MgH2, MnO/MgH2, and Mn/MgH2 multiphase interfaces, which improved the hydrogen storage performance of MgH2. The findings of this work may provide a new strategy for preparing novel and efficient catalysts for hydrogen storage applications.

Reactive destabilization and bidirectional catalyzation for reversible hydrogen storage of LiBH4 by novel waxberry-like nano-additive assembled from ultrafine Fe3O4 particles

LiBH4 containing 18.5 wt.% H2 is an attractive high-capacity hydrogen storage material, however, it suffers from high operation temperature and poor reversibility. Herein, a novel and low-cost bifunctional additive, waxberry-like Fe3O4 secondary nanospheres assembled from ultrafine primary Fe3O4 nanoparticles, is synthesized, which exhibits significant destabilization and bidirectional catalyzation towards (de)hydrogenation of LiBH4. With an optimized addition of 30 wt.% waxberry-like Fe3O4, the system initiated dehydrogenation below 100 °C and released a total of 8.1 wt.% H2 to 400 °C. After 10 cycles, a capacity retention of 70% was achieved, greatly superior to previously reported oxides-modified systems. The destabilizing and catalyzing mechanisms of waxberry-like Fe3O4 on LiBH4 were systematically analyzed by phase and microstructural evolutions during dehydrogenation and hydrogenation cycling as well as density functional theory (DFT) calculations. The present work provides new insights in developing advanced nano-additives with unique structural and multifunctional designs towards LiBH4 hydrogen storage.

In Situ Formed Ti/Nb Nanocatalysts within a Bimetal 3D MXene Nanostructure Realizing Long Cyclic Lifetime and Faster Kinetic Rates of MgH2.

Magnesium hydride (MGH) is a high-capacity and low-cost hydrogen storage material; however, slow kinetic rates, high dehydrogenation temperature, and short cycle life hindered its large-scale applications. We proposed a strategy of designing novel delaminated 3D bimetal MXene (d-TiNbCTx) nanostructure to solve these problems. The on-set dehydrogenation temperature of MGH@d-TiNbCTx composition was reduced to 150 °C, achieving 7.2 wt % of hydrogen releasing capacity within the range of 150-250 °C. This composition absorbed 7.2 wt % hydrogen within 5 min at 200 °C and 5.5 wt % at 30 °C within 2 h, while the desorption capacity (6.0 wt %) was measured at 275 °C within 7 min. After 150 cycles at 250 °C, the 6.5 wt % capacity was retained with negligible loss of hydrogen content. These results were attributed to the catalytic effect of in situ-formed TiH2/NbH2 nanocatalysts, which lead to dissociate the Mg-H bonds and promote of kinetic rates. This unique structure paves great opportunities for designing of highly efficient MGHs/MXene nanocomposites to improve the hydrogen storage performance of MGHs.

Promoting hydrogen industry with high-capacity Mg-based solid-state hydrogen storage materials and systems

Promoting hydrogen industry with high-capacity Mg-based solid-state hydrogen storage materials and systems

Heteroborospherene decorated with light metal as high capacity hydrogen storage material: Theoretical perspectives

In this work, the hydrogen storage capability in light metal (Na and K) decorated heteroborospherene C4B32 was investigated by using density functional theory (DFT) calculations. Na atoms can strongly bind to C4B32 with the average binding energy of 2.720 eV. The clusters of Na atoms decorated C4B32 are observed to be structurally stable even after the adsorption of H2 molecules. Each Na atom can adsorb 6H2 molecules with average adsorption energy of 0.199 eV/H2 yielding gravimetric H2 uptake of 8.99 wt%. However, the average adsorption energy of H2 molecules in K4C4B32 is much less than 0.2 eV. Therefore, Na decorated heteroborospherene C4B32 can act as an effective material for reversible H2 storage.

A DFT-D3 investigation on Li, Na, and K decorated C6O6Li6 cluster as a new promising hydrogen storage system

Because of the increasing demand for energy sources, searching for reversible and high-capacity hydrogen storage materials plays a vital role in the extensively utilizing of hydrogen as a clean energy source. In this study, dispersion-corrected density functional theory (DFT-D3) calculations are utilized to examine the possibility of storing H2 molecules on Li, Na, and K alkali metals decorated C6O6Li6 cluster. To evaluate H2 adsorption capability, the adsorption energies, electron density difference iso-surfaces, and charge-transfers are calculated and discussed. The results indicate that a hydrogen molecule is physisorbed on the Li@C6O6Li6, Na@C6O6Li6, and K@C6O6Li6 with average adsorption energies of −0.264, −0.150, and −0.109 eV, respectively. Double-sided alkali metal atoms decoration can lead to the maximum gravimetric density of 15.68, 14.49, and 13.79 wt% for 2Li@C6O6Li6–8H2, 2Na@C6O6Li6–10H2, and 2K@C6O6Li6–12H2 complexes, respectively. Finally, desorption temperatures reveal that the systems can operate as reversible hydrogen storage materials.

High-symmetry core-shell B12@Ca20C12: A nanocluster-based hydrogen storage material

Since the discovery of C60 fullerene, scientists devoted themselves to searching novel clusters. Among them, the high-symmetry clusters, especially clusters with Ih symmetry, has drawn increasing attention due to their special properties and stabilities. Here, a stable core-shell B12@Ca20C12 with Ih symmetry, which is featured as an icosahedral Ih-B12 centered on the dodecahedron Ca20C12, has been identified using first principles calculations. Its stability has been further confirmed by vibrational frequency analysis with the highest frequency of 834.9 cm−1 and the lowest frequency of 93.7 cm−1. Besides, molecular dynamics simulations indicate that its core-shell structure cannot be destroyed at 325 K under NVT ensembles with Nosé-Hoover chain thermostat. As for the electronic structure, 64 multi-center two-electron bonds were observed throughout the entire core-shell B12@Ca20C12 to keep the cluster maintain its core-shell configuration. More importantly, the core-shell B12@Ca20C12 can storage about 77 H2 molecules by closed-shell interactions with an average adsorption energy of −0.16 eV/H2, resulting in the gravimetric hydrogen density of 12.6 wt%. Based on these results we infer that core-shell B12@Ca20C12 is a potential high-capacity hydrogen storage material and might promote positive experimental efforts in designing excellent hydrogen storage materials.

Ti-decorated C30 as a high-capacity hydrogen storage material: insights from density functional theory

Employing density functional theory, we explore the hydrogen storage proficiency of titanium-decorated fullerene C30, an allotrope of carbon that comprises pentagonal and hexagonal rings.

Analysis of phase transformation in Mg2NiH4 via in situ synchrotron X-ray measurements

Mg-based alloys such as Mg2NiH4 are still attracting attention as high-capacity hydrogen storage materials. Mg2NiH4 undergoes the phase transformation between low-temperature (LT) and high temperature (HT) phases near the hydrogen desorption temperature. Herein, the crystallographic changes of Mg2NiH4 were investigated to clarify the behavior of the phase transformation by in situ synchrotron radiation X-ray measurements. The samples with three thermal histories (slow cooling, quenching from the HT phase, and hydrogenation below the transformation temperature) were prepared. These thermal histories affected the ratio of the LT phase without microtwinning (LT1) and with microtwinning (LT2). As the LT2/LT1 ratio increases, the phase transformation temperature decreases, and the phase transformation accelerates. X-ray diffraction peak analyses showed that the crystallite size and the lattice strain depend on the thermal history of the sample. X-ray absorption spectra indicated an increase in the short-range disorder of Mg2NiH4 when hydrogenated below the transformation temperature, which causes anomalous phase transformation and modulates the transformation temperature.

A quest to high-capacity hydrogen storage in zirconium decorated pentagraphene: DFT perspectives

The main crisis that impedes the way to successful hydrogen generation for energy purposes is the paucity of efficient hydrogen storage materials. Using First Principles calculations, we predict that zirconium atom adorned on the surface of an advanced carbon allotrope; penta graphene can attach 11 molecular hydrogens as a maximum, having average adsorption energy of −0.42 eV. This gives gravimetric hydrogen uptake of 14.8 wt%, far more than the Department of Energy's requirement of 5.5 wt%. Due to electron transfer from the 3d orbitals of zirconium to 2p orbital of carbon atom of pentagraphene, Zr is tightly linked to it, with a strong adsorption energy of −3.41 eV. The adsorption of hydrogen molecules on Zr is because of Kubas type of interactions involving electron transfer from Zr 3d orbital to hydrogen 1s orbital and subsequently, back donation from H 1s to Zr 3d orbital providing suitable adsorption energy for fuel cell applications which is higher than physisorption but lower than chemisorption energy. The stability of the structure (Zr-decorated pentagraphene) has been verified through Molecular Dynamics Simulations at 300 K and metal-metal clustering is prevented by the substantial energy barrier for the movement of Zr atom on pentagraphene. As the system is stable, adsorption energy of H2 molecules is in the desired range (0.2–0.7 certified by DoE), wt% of H2 is more than DoE's prescription, we infer from our DFT results that Zr-decorated pentagraphene may be a promising reversible high-capacity hydrogen storage material.

Computational evaluation of Ca-decorated nanoporous CN monolayers as high capacity and reversible hydrogen storage media

Developing novel materials with high-capacity and reversible properties for storing hydrogen (H2) is crucial for energy treatments. We here investigated comprehensively the H2 storage performance of the Ca-decorated g-CN (Ca@CN) monolayers using first-principles calculations. The Ca atoms can be uniformly decorated into the center of the pores of g-CN monolayers without aggregation. The Ca@CN monolayer has an average H2 adsorption energy of around 0.163–0.228 eV as well as high H2 storage capacity of 10.1 wt%. The stabilities of the H2 adsorption systems are confirmed by high hardness and low electrophilicity. The temperature of desorption is anticipated to be near the room temperature and ideal for fuel cell devices. The thermodynamic analysis along with desorption temperature reveal that the Ca@CN monolayer has promising potentials as reversible and high capacity hydrogen storage materials (HSM), which will motivate experimental efforts to synthesize the high-efficient HSM.

Design of metal-decorated beryllium carbide (Be2C) as a high-capacity hydrogen storage material with strong adsorption characteristics

Advanced research to design new two-dimensional materials with high capacity and efficient reversibility is one of the essential strategies for developing hydrogen storage applications. By employing density functional theory (DFT) and ab-initio molecular dynamic (AIMD) calculations comprising van der Waals interactions, we systematically studied the structural stability, electronic properties and the hydrogen storage properties of the pure beryllium carbide (Be2C) monolayer. Our results demonstrate that binding energies of H2 molecules in this system are exactly located in the desirable energy range. Furthermore, the stabilization of hydrogen by metal-decoration of Be2C on both sides was improved in comparison to that of pristine Be2C. 2Li@Be2C and 2K@Be2C were able to host up to 16 molecules of hydrogen reaching a gravimetric capacity of 10.21 and 8.48 wt%, respectively. The desorption temperature (TD) was found much higher than the critical point of hydrogen. In addition, the TD estimates were validated by AIMD simulations of hydrogenated Li@Be2C and K@Be2C. Thus, the Li/K@Be2C system can be a promising candidate for the experimental setup for hydrogen storage.

Density functional theory studies on C20 with substitutional TinNn impurities

In this paper, we have performed systematic theoretical surveys of C20 and its C20-2nTinNn nanocages with n = 1-8 at DFT. Full optimization indicates none of the structures collapse to open deformed as segregated heterofullerene. Also, in order to avoid the resulted strain of fused five-pentagon configuration, some of them deform their cage at the Ti-N bonds and appear cubic-like. Binding energy (Eb) increases, and the absolute heat of atomization │ΔHat│ of the designed C20-2nTinNn structures decreases, respectively, as the number of substituting Ti-N units increases. The calculated Eb of 57.05eV/atom and │ΔHat│ of 2437.40kcal/mol display C4Ti8N8 as the most thermodynamic stable heterofullerene where including eight separated Ti-N units through two double C═C bonds. In contrast, the calculated band gap of 2.06eV shows C18Ti1N1 as the best-insulated heterofullerene. Here isolable or extractable open-shell C18Ti1N1 heterofullerene must be kinetic stable species, and closed-shell C4Ti8N8 should be thermodynamic stable species. Compared to the suggested Ti-decorated B38 fullerene as a high capacity hydrogen storage material with large Eb (5.67eV/atom), our studied C20-2nTinNn heterofullerenes show the higher Eb with a range of 13.78 to 57.05eV/atom, the higher stability, and the higher capacity hydrogen storage. Each Ti-N unit can bind up to two hydrogen molecules with an average adsorption energy of 0.073eV/H2. While the C4Ti8N8 fullerene substituted with 8 Ti-N units can store 16 H2 molecules, the hydrogen gravimetric density (the hydrogen storage capacity) reaches up to 5.61 wt% with an average adsorption energy of 0.587eV/H2. Based on these results, we infer that C4Ti8N8 fullerene is a potential material for hydrogen storage with high capacity and might motivate active experimental efforts in designing hydrogen storage media.