Candidate For Hydrogen Storage Research Articles

Tuning clusters-metal oxide promoters electronic interaction of Ru-based catalyst for ammonia synthesis under mild conditions

Ammonia (NH3) is an excellent candidate for hydrogen storage and transport. However, producing NH3 under mild conditions is a long-term, arduous task. Atomic cluster catalysts (ACCs) have been shown to be effective for catalytic N2-to-NH3 conversion, opening the door to the development of efficient catalysts under mild conditions. Still, ACC formation with thermally stable catalytic sites remains a challenge because of their high surface free energy. Herein, we report anchoring Ba and/or Ce onto Ru ACCs (2 wt% Ru atomic clusters supported on N-doped carbon) to form so-called clusters–metal oxide promoters electronic interaction (CMEI) to stabilize the Ru atomic clusters. The resulting Ba/Ce/Ru ACCs significantly boost the NH3 synthesis rate to 56.2 mmolNH3 gcat−1 h−1 at 400 °C and 1 MPa, which is 7.5-fold higher than that of Ru ACC. The strengthened CMEI between the Ba/Ce and Ru atomic clusters across the Ba/Ce/Ru ACC enables electron transfer from Ba and/or Ce to Ru atomic clusters. As such, the electron-enriched Ru atom could facilitate electron transfer to N≡N bond π* orbitals, which would weaken the N≡N bond and drive the eventual conversion of N2 to NH3. This study offers insight into the role of CMEI in Ru ACCs and provides an effective approach for designing stable atomic cluster catalysts for NH3 synthesis.

From Back to Stage: Superior Cycling Stability of 2LiBH4−MgH2 Enabled by Anion Tuning

Abstract2LiBH4−MgH2 (Li‐RHC) is a potential hydrogen storage candidate with a capacity of 11.5 wt.%. However, its further application is severely limited by the long nucleation induction period and poor reversibility of end‐product. Unlike the traditional focus on the catalytical role of cation, herein, a new perspective of previously ignore anion tuning has been proposed, in which S2− bridges the reversible conversion between Li2S and MgS during de‐/hydrogenation cycling of Li‐RHC. Such conversion not only enhances the migration of Li+, leading to the rapid destabilization of B─H bonds without obvious nucleation period of MgB2, but also improves the cycling stability of Li‐RHC with capacity retention over 90% even after 50 cycles. The universal of this anion modulation has been verified, along with the matching criteria of the corresponding transition metal cation. The results highlight the contribution of anion, push anion modulation from back to stage and eventually broaden the selection of catalysts for Li‐RHC.

Nitrogen-Doped Graphene-Supported Nickel Nanoparticles Reveal Low Dehydrogenation Temperature and Long Cyclic Life of Magnesium Hydrides.

Magnesium hydride (MgH2) is a promising hydrogen storage candidate due to its large capacity; however, high dehydrogenation temperature and slow kinetic rates are the main bottlenecks. Herein, we proposed a strategy for designing nitrogen-doped graphene-supported Ni nanoparticles (NPs) (Ni@NC) to tackle these problems. The results showed that the MgH2 + 15 wt % Ni@NC nanocomposite reduced the on-set dehydrogenation temperature to 195 °C, which was 175 °C lower than pristine MgH2. In addition, MgH2 + 15 wt % Ni@NC achieved 1.7 and 6.5 wt % desorption capacities at 225 and 300 °C, respectively, while absorbing 5.5 wt % hydrogen at 100 °C. The MgH2 + 15 wt % Ni@NC nanocomposite showed high cyclic stability, achieving 98.0% capacity retention after 100 cycles at 270 °C with negligible loss in capacity. This remarkable hydrogen storage performance can be attributed to the homogeneous distribution of Ni NPs on N-doped graphene layers, in situ formed Mg2NiH2 NPs, and multiphasic regions, promoting the nucleation and growth process during hydrogenation/dehydrogenation, which stabilized and improved the cyclic stability. This strategy paves the way to developing high-performance MgH2 for large-scale applications.

Mg-decorated CN monolayer with enhanced hydrogen storage

Current hydrogen storage confronts safety and high energy cost challenges. Solid-state hydrogen storage provides an efficient pathway with lower cost and pressure conditions. Here, we perform density functional theory (DFT) calculations measuring the hydrogen storage properties of Mg-decorated CN monolayer. 8Mg@CN structure is confirmed based on energetic and geometric criteria and it can absorb up to 40 H2 molecules, achieving a high gravimetric density of 8.92 wt% over the US Department of Energy (DOE) target. The polarized H2 molecules are proven to be physiosorbed on Mg atoms to guarantee desorption. The electronic properties are studied to illustrate the electrostatic attractions between the H2 molecules and the Mg-decorated CN monolayer. Moreover, the desorption temperatures and adsorption pressures are calculated to illustrate the reversibility of hydrogen storage applications on 8Mg@CN. These results indicate 8Mg@CN could be a promising candidate for hydrogen storage with potentially reversible application.

Machine learning assisted design of BCC high entropy alloys for room temperature hydrogen storage

Body-centered cubic (BCC) alloy systems can theoretically store double amounts of hydrogen compared with commercial metal hydrides at room temperature, and BCC high entropy alloys (HEAs) have shown the potential to reach this theoretic limit. However, the high thermodynamic stability of the dihydrides formed during hydrogen storage results in high operating temperatures. Here, by employing multi-objective Bayesian optimization-aided density functional theory calculations, we discovered 8 new HEA candidates for hydrogen storage, including the VNbCrMoMn HEA that can store 2.83 wt% hydrogen at room temperature and atmospheric pressure, vastly exceeding the hydrogen capacities of 1.38 wt% and 1.91 wt% for commercial LaNi5H6 and TiFeH2. Such a high performance of VNbCrMoMn is ascribed to the optimized hydrogen absorption thermodynamics, which is achieved under the guidance of interpretable machine learning which revealed that the thermodynamics of the first and second stages of absorption are largely determined by the bulk modulus and the number of states in the d-band, respectively.

Density Functional Theory-Based Approaches to Improving Hydrogen Storage in Graphene-Based Materials.

Various technologies have been developed for the safe and efficient storage of hydrogen. Hydrogen storage in its solid form is an attractive option to overcome challenges such as storage and cost. Specifically, hydrogen storage in carbon-based structures is a good solution. To date, numerous theoretical studies have explored hydrogen storage in different carbon structures. Consequently, in this review, density functional theory (DFT) studies on hydrogen storage in graphene-based structures are examined in detail. Different modifications of graphene structures to improve their hydrogen storage properties are comprehensively reviewed. To date, various modified graphene structures, such as decorated graphene, doped graphene, graphene with vacancies, graphene with vacancies-doping, as well as decorated-doped graphene, have been explored to modify the reactivity of pristine graphene. Most of these modified graphene structures are good candidates for hydrogen storage. The DFT-based theoretical studies analyzed in this review should motivate experimental groups to experimentally validate the theoretical predictions as many modified graphene systems are shown to be good candidates for hydrogen storage.

Underground Hydrogen Storage Safety: Experimental Study of Hydrogen Diffusion through Caprocks

Underground Hydrogen Storage (UHS) provides a large-scale and safe solution to balance the fluctuations in energy production from renewable sources and energy consumption but requires a proper and detailed characterization of the candidate reservoirs. The scope of this study was to estimate the hydrogen diffusion coefficient for real caprock samples from two natural gas storage reservoirs that are candidates for underground hydrogen storage. A significant number of adsorption/desorption tests were carried out using a Dynamic Gravimetric Vapor/Gas Sorption System. A total of 15 samples were tested at the reservoir temperature of 45 °C and using both hydrogen and methane. For each sample, two tests were performed with the same gas. Each test included four partial pressure steps of sorption alternated with desorption. After applying overshooting and buoyancy corrections, the data were then interpreted using the early time approximation of the solution to the diffusion equation. Each interpretable partial pressure step provided a value of the diffusion coefficient. In total, more than 90 estimations of the diffusion coefficient out of 120 partial pressure steps were available, allowing a thorough comparison between the diffusion of hydrogen and methane: hydrogen in the range of 1 × 10−10 m2/s to 6 × 10−8 m2/s and methane in the range of 9 × 10−10 m2/s to 2 × 10−8 m2/s. The diffusion coefficients measured on wet samples are 2 times lower compared to those measured on dry samples. Hysteresis in hydrogen adsorption/desorption was also observed.

Tuning Hydrogen Storage Properties in La1−xYxNi4.5Cu0.5 (x = 0.1; 0.2; 0.3; 0.4, 0.5) Alloys

Metal hydrides of AB5 compositions have been investigated over the years as they offer extraordinary volumetric hydrogen densities with high cycling stability and purity of released hydrogen. Moreover, by doping with different elements, the sorption properties of alloys can be significantly changed according to their foreseen applications. In this contribution, we report the synthesis routes and hydrogenation characteristics of La1−xYxNi4.5Cu0.5. The synthesized alloys exhibit excellent structural purity with all reflections indexed by the hexagonal P6/mmm structure. It was found that the Y content can easily tune (raise) the equilibrium pressures of the pressure–composition isotherms, while overall gravimetric density remains at a level exceeding 1.5 wt.% up to x = 0.3 then strongly decreases. The pressure range for desorption can be tuned from 1.5 to 5 bars at room temperature. Some alloys (x = 0; 0.2) exhibit very good stability during 1000 cycles of hydrogen loading and unloading. Furthermore, activation of the alloys is prompt, making them good candidates for stationary hydrogen storage, non-mechanical hydrogen compressors, or soft actuators.

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

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

Thermodynamics of Reversible Hydrogen Storage: Are Methoxy-Substituted Biphenyls Better through Oxygen Functionality?

The reversible hydrogenation/dehydrogenation of aromatic molecules, known as liquid organic hydrogen carriers, is considered as an attractive option for the safe storage and release of elemental hydrogen. The recently reported efficient synthetic routes to obtain methoxy-biphenyls in high yield make them promising candidates for hydrogen storage. In this work, a series of methoxy-substituted biphenyls and their structural parent compounds were studied. The absolute vapour pressures were measured using the transpiration method and the enthalpies of vaporisation/sublimation were determined. We applied a step-by-step procedure including structure–property correlations and quantum chemical calculations to evaluate the quality of thermochemical data on the enthalpies of phase transitions and enthalpies of formation of the studied methoxy compounds. The data sets on thermodynamic properties were evaluated and recommended for calculations in chemical engineering. A thermodynamic analysis of chemical reactions based on methoxy-biphenyls in the context of hydrogen storage was carried out and the energetics of these reactions were compared with the energetics of reactions of common LOHCs. The influence of the position of the methoxy groups in the rings on the enthalpies of the reactions relevant for hydrogen storage was discussed.

A first-principles study of hydrogen storage on pristine and Li-decorated aluminium monolayer

Hydrogen storage is a major challenge for the development of hydrogen energy technology, and this has inspired the search for novel materials with high storage capacity and reversibility. In this work, we study the use of pristine and Li-decorated metallic honeycomb aluminium monolayer for hydrogen storage, using density functional theory based methods. Our findings reveal that the hydrogen adsorption energies are significantly improved upon Li decoration, from an average of −0.045 eV for pristine monolayer to an average of −0.18 eV. Further, the Li-decorated monolayer can adsorb up to 3H2 molecules per Li atom, and the binding remains almost constant for different adsorbing sites for the Li atom. Additionally, we studied the impact of pressure and temperature on the hydrogen storage capability of the decorated monolayer and found that all of the H2 molecules adsorbed on the monolayer are stable at mild pressure at room temperature. The DOE's target of 5.5 wt % for hydrogen gravimetric densities in 2025 may be exceeded as a result of the metal decoration on both sides of the monolayer. Our results highlights Li-decorated low-cost metallic Aluminum sheets as potential candidates for hydrogen storage.

Feasibility of hydrogen storage in depleted shale gas reservoir: A numerical investigation

Due to the low operation cost, high containment security, and large storage capacity, depleted shale gas reservoirs are considered as promising options for large-scale hydrogen storage. However, its feasibility has not been systematically examined yet. It is still unknown about whether the deliverability (injection/withdrawal) capacity could meet the energy supply/demand and how the depletion time, cushion gas selection, injection/withdrawal strategy will influence the performance of this scenario.Therefore, we present a numerical compositional modelling investigation on hydrogen storage in a partially depleted Fuling shale gas reservoir in China. The results demonstrated that: 1) a high injection/withdrawal capacity could be achieved through a single shale play pad in the area of interest as approximately 5.4 × 108 Sm3 hydrogen could be stored and 3 × 108 Sm3 could be recovered in each cycle (equal to 0.54 TWh of power output). 2) CH4 production is inhibited once hydrogen storage project is performed, an early depletion time could significantly reduce CH4 production but slightly improve H2 withdrawal. 3) Cushion gas injection is beneficial to reducing H2 loss and enhancing 2.8% H2 recovery, while the main drawback of this operational measure is an increase in capital cost in gas separation due to lower H2 purity in the produced gas.This work demonstrates that shale gas reservoir is a promising candidate for hydrogen storage, which is beneficial to the implementation of large-scale hydrogen economy and the operation of hydrogen supply chain.

Hydrogen adsorption by a porous bimetallic solid solution carbide MAX phases synthesized in an open atmosphere

Multilayer and porosity are significant traits for energy storage materials, especially for hydrogen storage and utilization. However, the material must first undergo subsequent sequential investigation for accurate quantification to be a candidate for hydrogen storage. The mixed metallic MAX phase and their derivatives MXene have the potential to be used for hydrogen storage. In this paper, we describe the formation of low temperature (1100 °C), porous, and high purity (84.92 %) bimetallic solid solution Titanium Vanadium Aluminum Carbide (TiVAlxC) MAX phases in an open atmosphere, where the variation of x, e.g., Al mole content, is critical for obtaining high purity metallic solid solution MAX phases. The BET comparative analysis shows the textural features of the TiVAlxC with change in Al and end phases, i.e., Ti2AlC (Titanium Aluminum Carbide) and (Vanadium Aluminum Carbide) V2AlC. The outcomes are evident that impurity, crystallinity, and crystallite size impact the textural properties of the synthesized MAX phases. Corelative findings on accurate quantification of hydrogen uptake based upon textural properties. The gravimetric hydrogen storage capacity of Ti2AlC, TiVAl1.3C, and V2AlC phases are 0.33, 0.62, and 1.29%wt, respectively. The gravimetric analysis provided valuable insights into the isothermal hydrogen adsorption of TiVAlxC and its end phases, demonstrating these materials' ability to be used for future hydrogen storage.

Studies of the hydrogen energy storage potentials of Fe- and Al-doped silicon carbide nanotubes (SiCNTs) by optical adsorption spectra analysis

This work investigated the hydrogen adsorption potentials of the Fe-doped (magnetic) and Al-doped (nonmagnetic) armchair silicon carbide nanotubes (SiCNTs) as candidates for hydrogen storage materials. Calculations of the electronic transport properties of the investigated systems were performed using the popular density functional theory as implemented in quantum ESPRESSO while corrections to quasi-particle energies were performed using Yambo codes within many-body perturbation theory. The obtained results of the structural properties revealed that pristine single-walled SiCNT was found to be more stable due to its higher binding energy of −393.85 eV while less stability was recorded with Al-doped SiCNT having binding energy of −393.81 eV. Furthermore, the stability of the Fe-doped SiC nanotube was found to be normal between bond lengths 1.73 Å to 1.79 Å, indicating its great potential to accommodate more Fe dopants. In terms of electronic properties, the Fe-doped SiC nanotube demonstrated half-metallic and half-monometallic properties. Ferromagnetic features were also observed for the Fe-doped SWSiCNT when Fe replaced the Si atoms, while antiferromagnetic features were observed when Fe replaced the C atoms. The results obtained from optical spectra analysis indicated that Fe-doped SiCNT adsorbed hydrogen only at 1.8 eV which is the lower part of the visible spectrum while Al-doped SiCNT adsorbed hydrogen at energy levels 0 eV, 2.8 eV and 7.1 eV which extended from visible to UV regions. Therefore, Al-doped SiCNT is recommended as a better candidate for hydrogen storage under ambient conditions.

A Nanoscale Ternary Amide‐rGO Composite with Boosted Kinetics for Reversible H2 Storage

AbstractMetal amides are attractive candidates for hydrogen storage due to their high volumetric and gravimetric hydrogen densities. However, the sluggish kinetics and competing side reactions during hydrogen uptake and release limit their practical use. Here, a novel nanoconfined Li2Mg(NH)2@reduced graphene oxide (rGO) composite is presented, which is fabricated using a melt‐infiltration method with a minimum weight penalty of only 2 wt.%. The presence of rGO ensures close contact between the active phases, effectively preventing aggregation during cycling process. As a result, the reversible capacity of Li2Mg(NH)2@rGO reaches 4.42 wt.%, with no capacity degradation observed after multiple cycling. Theoretical calculations show that rGO catalyzes the hydrogen bond cleavage at the Mg‐amide/Li hydride interface, leading to local dehydrogenation hotspots and significantly improves kinetics of dehydrogenation compared to the bulk counterpart. This study provides a promising strategy for designing metal imide‐based composites to overcome the kinetic limitations and improve their reversible hydrogen storage performance.

PdNi biatomic clusters from metallene unlock record-low onset dehydrogenation temperature for bulk-MgH2.

Hydrogen storage has long been a priority on the renewable energy research agenda. Due to its high volumetric and gravimetric hydrogen density, MgH2 is a desirable candidate for solid-state hydrogen storage. However, its practical use is constrained by high thermal stability and sluggish kinetics. Here, we report PdNi bilayer metallenes as catalysts for hydrogen storage of bulk-MgH2 near ambient temperature. Unprecedented 422 K beginning dehydrogenation temperature and up to 6.36wt.% reliable hydrogen storage capacity were achieved. Fast hydrogen desorption was also provided by the system (5.49wt.% in 1h, 523 K). The in-situ generated PdNi alloy clusters with suitable d-band centers were identified as the main active sites during the de/re-hydrogenation process by AC-TEM and theoretical simulations, while other active species including Pd/Ni pure phase clusters and Pd/Ni single atoms obtained via metallene ball milling, also enhance reaction. These findings present fundamental insights into active species identification and rational design of highly efficient hydrogen storage materials. This article is protected by copyright. All rights reserved.

Stable two-dimensional Na decorated BeN4: a potential candidate for hydrogen storage

Stable two-dimensional Na decorated BeN4: a potential candidate for hydrogen storage

Hydrogen storage in Na decorated heteroborospherene Si4B32: Insights from density functional study

This article investigates the structural stability and hydrogen adsorption performance of Na-decorated heteroborospherene Si4B32 using density functional theory (DFT) methods. DFT calculations demonstrate that six sodium (Na) atoms can successfully and chemically bind to the surface of heteroborospherene Si4B32, exhibiting a substantial average binding energy of 2.465 eV without clustering. Moreover, the resulting Na6Si4B32 structure retains its integrity even after absorbing up to 30 hydrogen (H2) molecules, with an average adsorption energy of 0.251 eV/H2. Utilizing DFT analysis, the gravimetric density of Na6Si4B32·(H2)30 can reach 9.143 wt%. Additionally, employing ab initio molecular dynamics (AIMD) simulations, we find that a significant fraction of the H2 molecules desorb from Na6Si4B32 at 300K within 1000 fs. These findings establish the potential of Na-decorated heteroborospherene Si4B32 as a promising candidate for reversible hydrogen storage. The successful binding of Na atoms without clustering and the substantial H2 adsorption capacity, coupled with the structural stability and facile H2 desorption observed at moderate temperatures, highlight the viability of this material for practical hydrogen storage applications.

Microbial risk assessment for underground hydrogen storage in porous rocks

Geological hydrogen storage, e.g. in depleted gas fields (DGF), can overcome imbalances between supply and demand in the renewable energy sector and facilitate the transition to a low carbon emissions society. A range of subsurface microorganisms utilise hydrogen, which may have important implications for hydrogen recovery, clogging and corrosion. We gathered temperature and salinity data for 75 DGF on the UK continental shelf and mapped their suitability for hydrogen storage in terms of the risk of adverse microbial effects, based on a novel collection of microbial growth constraints. Data on wind and solar operational capacities as well as offshore gas and condensate pipeline infrastructure were overlaid on the microbial risk categorization to optimize geographical centers of green hydrogen production, transport infrastructure and underground storage. We recommend storing hydrogen in 9 DGF that are at no microbial risk due to temperatures > 122 °C, or in the 35 low-risk DGF with temperatures > 90 °C. We recommend against utilising high-risk DGF with temperatures < 55 °C (9 DGF). Alignment with centers for renewable energy production and out-of-use pipelines suitable for repurposing to transport hydrogen suggests that no-risk and low-risk DGF in the Southern North Sea are the most suitable candidates for hydrogen storage. Our results advise site selection choices in geological hydrogen storage in the UK. Our methodology is applicable to any underground porous rock system globally.

In situ formed MgTi2O4 from MgO improving the cycling stability of MgH2

Magnesium hydride (MgH2) is a potential candidate for hydrogen storage due to its high gravimetric and volumetric hydrogen capacities. However, high operating temperature and reversible H2 capacity attenuation inhibit its commercial application. To overcome these issues, we synthesized an N ion-doped Na2TiO3 (denoted as N-NaTiO) catalyst by reducing TiO2 with NaNH2. Experimental results show that the addition of 5 wt% N-NaTiO can lower the dehydrogenation peak temperature of MgH2 from 328 to 239 °C, and 6.0 wt% H2 is quickly released in ca. 4 min at 300 °C. In particular, the modified MgH2 exhibits a high reversible hydrogen capacity of 6.7 wt% which is equal to a retention of 94.4% after 250 cycles. Reaction mechanism investigations reveal that hydrogen insertion and removal during the ab/desorption processes are consistent with the reversible change of titanium valence states in the catalyst. In addition, it is observed that there is an irreversible evolution of MgO to MgTi2O4 at the interface between the catalyst and MgH2 during the cycling process, which is linked to the improvement of the ab/desorption kinetics and cycle stability.