Potential Hydrogen Storage Research Articles

First-principles study on a Li-decorated two-dimensional g-C6N6 monolayer: A promising ambient temperature reversible H2 storage material

Designing novel materials that exhibit superior reversibility and function under ambient conditions can facilitate the development of hydrogen energy applications. Two-dimensional (2D) g-C6N6 monolayers show great potential for use in hydrogen storage owing to their nanoporous structure, ultralight mass, and flexible electronic structure. However, the hydrogen storage potential of these materials is limited by the naturally weak interaction between 2D materials and hydrogen molecules caused by van de Waals forces. To address this issue, we studied the hydrogen storage performance of the complex by decorating active Li ions on a 2D g-C6N6 substrate through first-principles calculations. Our results showed that modifying the Li ions did not cause the original planar structure to deform but rather induced more active sites for hydrogen adsorption by establishing an electrostatic field between the Li ions and the g-C6N6 monolayer. Through this modification, reversible hydrogen storage was achieved under ambient conditions with an average adsorption energy of −0.197 eV/H2 and a high gravimetric capacity of 5.88 wt%. The electronic properties of the material were systematically investigated, and the results suggested that the enhanced capacity of the Li@ g-C6N6 system to store hydrogen resulted from the formation of a polarization field and the induced electrostatic effect. Our research offers a new possibility for achieving reversible hydrogen energy storage at room temperature.

First-principles study of hydrogen storage application of Ti3C2Tx monolayer MXene

MXene, with its high aspect ratio and adjustable surface properties, has garnered significant attention in the realm of hydrogen storage research. For the first time, considering a ternary/quaternary mixed terminated MXene surface, the authors have investigated comprehensively the hydrogen storage potential of two-dimensional (2D) titanium carbide Ti3C2Tx monolayer MXene using density functional theory (DFT). By considering mixed terminated surfaces, this study indicated the locally induced dipole due to the mixed termination is beneficial in facilitating hydrogen adsorption with stronger average adsorption energies than that of the uniform F-/O-/OH-/H-terminated surfaces. The authors estimated a compelling average H2 surface adsorption energy on the ternary mixed termination and total surface storage capacity to be −0.14 eV/H2 and ∼2 wt% H2, which is comparable to that of the metal-organic frameworks (MOFs). This study also reveals the importance of the local surface chemistry effects on hydrogen adsorption.

Density Functional Theory Investigation of Cu, Ni, and Ag Inclusion in ZSM-5 to Study Dihydrogen Binding for Cryogenic Molecular Sieve Bed Adsorber in Nuclear Fusion Systems

A computational investigation of Cu-, Ni-, and Ag-introduced ZSM-5 as potential hydrogen storage materials for nuclear fusion energy systems is performed. Among the 24 distinct tetrahedral sites of the monoclinic phase of ZSM-5, systematic periodic density functional theory (DFT) computations have been carried out on 15 experimentally identified T sites that show clear Al site preference and stability in high Si ZSM-5. Adsorption energies estimated from DFT studies have revealed that the T sites in the sinusoidal channels T4 and T10 are the most stable for including all three metal ions. Hence, these should also be considered as potential active sites for dihydrogen binding investigations in addition to the common T12 site in the intersection. The average hydrogen binding energies at these representative T sites were −79 to −45 kJ/mol, which correlates well with both the metal-H2 distance and H-H bond elongation distance. The computed hydrogen bond stretching frequency values were in the 3300 to 3755 cm−1 range upon adsorption of H2 onto the Ni, Cu, and Ag, indicating Kubas-type dihydrogen complex formation. The evidence for dihydrogen binding was also obtained from investigating the σ donation and back donation between the metal ion valence orbitals and the H2σ, H2σ* orbitals through projected density of states and natural bond order analysis. Our analysis indicates that Ni is better stabilized in the framework sites and is considered a potential candidate for dihydrogen binding.

A Critical Geological Evaluation of the Hydrogen Storage Potential in the Cousland Gas Field, Midland Valley of Scotland

Hydrogen is envisaged to be an important element in the drive to replace hydrocarbons in the energy mix and its geological storage in man-made salt caverns or porous subsurface reservoirs onshore in the United Kingdom is being actively investigated. It has recently been suggested that porous Carboniferous sandstone reservoirs of the partially depleted and abandoned Cousland Field, located c.15 km SE of Edinburgh, could be used for the storage of hydrogen as part of efforts to decarbonise the industrialised and heavily populated central belt of Scotland. The gas field occurs in an onshore surface anticline situated in a culmination along a topographic ridge on the eastern flank of the Midlothian Coalfield. Mapping of outcropping beds led to a well, Cousland-1, being drilled in 1937-39 as part of a national campaign of oil exploration, which discovered natural gas in two thin sands. Despite the initial success, all the subsequent five appraisal wells, drilled between 1939 and 1960, were devoid of commercial hydrocarbons. Despite the disappointing drilling campaign, the field was still developed based on the original Cousland-1 well result and some 0.25 billion standard cubic feet (“scf”) (7.0 million m3) of gas were produced between 1939 and 1965 before the well was plugged and abandoned. This paper draws upon and integrates hitherto unpublished historical records, obtained from the archives of the UK Onshore Geophysical Library, to critically examine the possibility that the Cousland gas field might be re-purposed for hydrogen storage. These studies conclude that it is currently not possible to demonstrate the subsurface configuration, host reservoir distribution or sealing mechanism of the proposed storage container because the information required is not available and may be impossible to obtain. Rather than supporting the case for hydrogen storage, our new evaluation demonstrates that the Cousland field is a poor site that fails to meet the criteria for safe subsurface storage and should not be used for this purpose until and unless the significant challenges can be addressed.

Hydrogen Storage Potential in Natural Gas Deposits in the Polish Lowlands

In the future, the development of a zero-carbon economy will require large-scale hydrogen storage. This article addresses hydrogen storage capacities, a critical issue for large-scale hydrogen storage in geological structures. The aim of this paper is to present a methodology to evaluate the potential for hydrogen storage in depleted natural gas reservoirs and estimate the capacity and energy of stored hydrogen. The estimates took into account the recoverable reserves of the reservoirs, hydrogen parameters under reservoir conditions, and reservoir parameters of selected natural gas reservoirs. The theoretical and practical storage capacities were assessed in the depleted natural gas fields of N and NW Poland. Estimates based on the proposed methodology indicate that the average hydrogen storage potential for the studied natural gas fields ranges from 0.01 to 42.4 TWh of the hydrogen energy equivalent. Four groups of reservoirs were distinguished, which differed in recovery factor and technical hydrogen storage capacity. The issues presented in the article are of interest to countries considering large-scale hydrogen storage, geological research organizations, and companies generating electricity from renewable energy sources.

Pressure mediated phase transition and dihydrogen bonding formation in trimethylamine borane

Trimethylamine borane as a potential hydrogen storage material was investigated at high pressures up to 35 GPa where its structural stability, phase transformation, bonding and electronic properties were elucidated.

Electronic, phononic, and superconducting properties of FeHx (x=1-6) at 150 GPa

Metal hydrides have been studied extensively due to their intriguing superconductivity and potential hydrogen storage capacities. Here, the structural, electronic, phononic, and superconducting properties of iron hydrides FeHx (x=1-6) are...

Hydrogen storage capacity of two-dimensional MoS2

Hydrogen storage holds a crucial place for the future of the world in terms of green energy. Two-dimensional materials, in particular, are important in this regard. The aim of this study is to evaluate the performance of MoS2 which is one of the most popular member of two-dimensional materials family. To do this, bulk and exfoliated MoS2 were used. Firstly, the liquid phase exfoliation method was employed to obtain exfoliated MoS2 layers. Then, the hydrogen storage potential of the bulk and exfoliated MoS2 was addressed under 1, 3, 5, 7, and 9 bar hydrogen pressure. After the absorption process, all the samples were characterized using XRD, Raman Spectrometer, and BET ahead of evaluating their hydrogen storage potential. The XRD pattern showed that the peak positions of bulk and exfoliated MoS2 were not affected critically by hydrogen storage. In the Raman spectra, the A1g and E2g1 peaks of all hydrogenated materials shifted to low wavelengths. Moreover, the BET measurements revealed that the specific surface area and the pore size of the bulk MoS2 were 12.31 m2/g and ≤67.46 nm respectively. Additionally, the specific surface area and the pore size of the exfoliated MoS2 were 23.16 m2/g and ≤69.28 nm, respectively. The hydrogen storage potential of the bulk and the exfoliated MoS2 was evaluated through an MFC in sccm unit. The bulk and exfoliated MoS2 stored 220 and 450 sccm hydrogen, respectively. Besides, the weight percent hydrogen storage for H–MoS2 and H-exfoliated MoS2 was determined to be 1.2 and 2.4 wt%, respectively. In summary, this study has shown that exfoliated MoS2, one of the two-dimensional materials, can play a critical role for hydrogen storage due to their high specific surface area.

Lithuania’s geo-energy landscape: a brief overview of CCUS, hydrogen, and geothermal

Lithuanian energy landscape is changing because of a strong push to reduce carbon emissions and reliance of fossil-based energy production. EU climate directive promotes investments into carbon capture and storage technologies along with renewable energy resource development. CCUS, hydrogen and geothermal are some technologies which could promote reduction in carbon emissions and along with reducing dependence on fossil-based energy sources. Lithuania already has large potential for carbon and hydrogen storage and in past had a working geothermal power plant for district heating. In this work we revisit the carbon storage potential in Lithuania subsurface and provide a high-level estimate of potential of generating hydrogen energy from depleted hydrocarbon fields using in-situ methods. We also evaluate the prospects of development of geothermal energy production from deep Cambrian reservoirs where temperature above 85 °C has been documented.

Hydrogen generation from NaBH4 for portable proton exchange membrane fuel cell

Sodium borohydride (NaBH4) is considered as the most potential hydrogen storage material for portable proton exchange membrane fuel cells (PEMFC) because of its high theoretical hydrogen capacity. However, the slow and poor kinetic stability of hydrogen generation from NaBH4 hydrolysis limits its application. There are two main factors influencing the kinetics stability of hydrogen generation from NaBH4. One factor is that the alkaline by-products (NaBO2) of the hydrolysis reaction can increase the pH of the solution, thus inhibiting the reaction process. It mainly happens in the NaBH4 solution hydrolysis system. Another factor is that the monotonous increase in reaction temperature leads to uncontrollable and unpredictable hydrolysis rates in the solid NaBH4 hydrolysis system. This is due to the excess heat generated from this exothermic reaction in the initial reaction of NaBH4 hydrolysis. In this perspective, we summarize the latest research progress in hydrogen generation from NaBH4 and emphasize the design principles of catalysts for hydrogen generation from NaBH4 solution and solid state NaBH4. The importance of carbon as catalyst support material for NaBH4 hydrolysis is also highlighted.

Diffusion quantum Monte Carlo study on magnesium clusters as large as nanoparticles

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.

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.

A DFT study of structural, electronic, mechanical, phonon, thermodynamic, and H2 storage properties of lead-free perovskite hydride MgXH3(X=Cr, Fe, Mn)

Perovskite hydride materials have gained significant attention for their potential in hydrogen storage, a key component of renewable energy systems. In this study, we used density functional theory (DFT) to investigate the structural, vibrational, electronic, mechanical, thermodynamic, and hydrogen storage properties of MgXH3 (X = Cr, Fe, Mn) hydrides. The energy volume curves were used to determine optimized lattice parameters of MgCrH3(3.4590 Å), MgFeH3(3.0284 Å), and MgMnH3(3.3485 Å). The Born criteria for elastic constant (Cij) showed that the hydrides are mechanically stable, whereas the phonon dispersion curves showed their dynamic stability. The calculated electronic properties revealed the metallic nature of hydrides under investigation. The Cauchy pressure (Cp) revealed the brittle and ductile behavior. The calculated gravimetric hydrogen storage capacity of MgCrH3, MgFeH3, and MgMnH3 hydrides was 3.771, 3.606, and 3.643 wt% respectively. The electronic and thermodynamic properties suggest that MgXH3 hydrides can conduct electrical as well as thermal energy. Our results provide insight into the potential of MgXH3(X = Cr, Fe, Mn) perovskite hydride material for hydrogen storage application.

Li-decorated bilayer borophene as a potential hydrogen storage material: A DFT study

Two-dimensional (2D) materials have recently attracted much attention in the field of hydrogen storage, owing to their beneficial properties such as high surface-to-volume ratio and light weight. Motivated by recent experimental developments of bilayer borophene (BL) sheets, we investigate the suitability of hydrogen storage on Li-decorated BL via density functional theory (DFT) calculations. The H2 molecules are adsorbed on BL sheet via weak physisorption. By decorating BL with Li atoms, its hydrogen storage performance has been improved. We find that Li atoms can firmly adsorb on the substrate without forming clusters. Meanwhile, the Li-decorated structure exhibits good stability, verified by molecular dynamics calculations. Remarkably, in the fully loaded case, the compound obtains a 6.08 wt% H2 content and 0.13 eV/H2 average adsorption energy, which is promising for onboard hydrogen storage. Furthermore, electronic structure analysis reveals the electrostatic nature of interactions between the H2 molecules and the protruding Li atoms on BL sheets, which originates from polarization and orbital hybridization. Overall, our results suggest that Li-decorated BL is a promising candidate for potential hydrogen storage applications, and contribute to a better understanding of bilayer materials for hydrogen storage.

Hydrogen storage capacity of salt caverns and deep aquifers versus demand for hydrogen storage: A case study of Poland

Geological structures in deep aquifers and salt caverns can play an important role in large-scale hydrogen storage. However, more work needs to be done to address the hydrogen storage demand for zero-emission energy systems. Thus the aim of the article is to present the demand for hydrogen storage expressed in the number of salt caverns in bedded rock salt deposits and salt domes or the number of structures in deep aquifers. The analysis considers minimum and maximum hydrogen demand cases depending on future energy system configurations in 2050. The method used included the estimation of the storage capacity of salt caverns in bedded rock salt deposits and salt domes and selected structures in deep aquifers. An estimation showed a large hydrogen storage potential of geological structures. In the case of analyzed bedded rock salt deposits and salt domes, the average storage capacity per cavern is 0.05–0.09 TWhH2 and 0.06–0.20 TWhH2, respectively. Hydrogen storage capacity in analyzed deep aquifers ranges from 0.016 to 4.46 TWhH2. These values indicate that in the case of the upper bound for storage demand, there is a need for the 62 to 514 caverns, depending on considered bedded rock salt deposits and salt domes or the 9 largest analyzed structures in deep aquifers. The results obtained are relevant to the discussion on the global hydrogen economy, and the methodology can be used for similar considerations in other countries.

Compositional tuning of A2B7-type La0.7–xYxMg0.3Ni3.5 alloys for gaseous hydrogen storage

Rare earth-based superlattice alloys have great potential for gaseous hydrogen storage, as well as successful application as nickel-metal hydride batteries anodes. In this work, Y substitution was carried out to adjust the gaseous hydrogen storage properties of A2B7-type La0.7Mg0.3Ni3.5 alloys. The results indicate a multiphase structure in the alloys comprised of the main rhombohedral Gd2Co7 and PuNi3 phases, with a small amount of CaCu5 phase. Moreover, the Y substitution results in higher abundance of the Gd2Co7 phase. The alloy La0.42Y0.28Mg0.3Ni3.5 exhibits a hydrogen storage capacity of 1.55 wt% at 298 K and a desorption plateau pressure of 0.244 MPa. In addition, this alloy demonstrates a stable cycle life by a capacity retention of 94.2% after 50 cycles, with the main capacity degradation occurring during the initial 20 cycles. This work accentuates the potential of the La–Y–Mg–Ni-based superlattice alloys for applications in solid-state hydrogen storage.

Solid state hydrogen storage: Decoding the path through machine learning

We present a machine learning (ML) framework HEART (HydrogEn storAge propeRty predicTor) for identifying suitable families of metal alloys for hydrogen storage under ambient conditions. Our framework includes two ML models that predict the hydrogen storage capacity (HYST) and the enthalpy of hydride formation (THOR) of multi-component metal alloys. We demonstrate that a chemically diverse set of features effectively describes the hydrogen storage properties of the alloys. In HYST, we use absorption temperature as a feature which improved H2wt% prediction significantly. For out-of-the-bag samples, HYST predicted H2wt% with R2 score of 0.81 and mean absolute error (MAE) of 0.45 wt% whereas R2 score is 0.89 and MAE is 4.53 kJ/molH2 for THOR. These models are further employed to predict H2wt% and ΔH for ∼ 6.4 million multi-component metal alloys. We have identified 6480 compositions with superior storage properties (H2wt% > 2.5 at room temperature and ΔH < 60 kJ/molH2). We have also discussed in detail the interesting trends picked up by these models like temperature dependent variation in the rate of hydrogenation and alloying effect on H2wt% and ΔH in different families of alloys. Importantly certain elements like Al, Si, Sc, Cr, and Mn when mixed in small fractions with hydriding elements like Mg, Ti, V etc. systematically reduce ΔH without significantly compromising the storage capacity. Further upon increasing the number of elements in the alloy i.e from binary to ternary to quaternary, the number of compositions with lower enthalpies also increases. From the 6.4 million compositions, we have reported new alloy families having potential for hydrogen storage at room temperature. Finally, we demonstrate that HEART has the potential to scan vast chemical spaces by narrowing down potential materials for hydrogen storage.

Data-driven modeling to predict adsorption of hydrogen on shale kerogen: Implication for underground hydrogen storage

The interaction of hydrogen in shale gas formations holds significant interest for long-term subsurface hydrogen storage. Accurately and rapidly predicting hydrogen adsorption in these formations is crucial for assessing underground hydrogen storage potential. Many laboratory experiments and molecular simulations have been conducted to determine hydrogen adsorption. However, laboratory experiments and molecular simulations require complex setups and extensive calculations, which can be time-consuming. Consequently, end-users may prefer quick and accurate prediction of hydrogen adsorption to reduce the experimental and computational burden. This study introduces a novel model for predicting hydrogen adsorption using gradient boosting regression and available molecular simulation data from the literature. The data-driven model predicts hydrogen adsorption on kerogen structures based on pressure, temperature, adsorbed methane, hydrogen-to‑carbon ratio, oxygen-to‑carbon ratio, and kerogen density. We compared gradient-boosting regression with other machine learning tools, including artificial neural networks, symbolic regression assisted with genetic programming, decision trees, and random forests in terms of their capability to predict H2 adsorption on shale kerogen. A simple mathematical equation based on symbolic regression via genetic programming has also been provided, with training and testing coefficients of determination of 88.4% and 85.8%, respectively. However, the digital model created using gradient boosting regression outperformed all other machine learning tools, achieving a coefficient of determination of 99.6% for training data and 94.6% for testing data. A sensitivity analysis was also conducted that demonstrates the robustness of the developed model. In the case of kerogen type A, the order of increasing hydrogen adsorption is KIA < KIIA<KIIIA. Conversely, for kerogen type B, the trend is KIIA<KIIC<KIIB<KIID in terms of increasing hydrogen adsorption. This developed digital model offers higher prediction accuracy and finds applications in storing hydrogen in shale gas formations. The proposed model offers a substantial time-saving advantage in predicting hydrogen adsorption compared to laborious and time-consuming laboratory experiments and/or molecular simulations.

Synthesis of Ni and Mg MOF-derived carbons for potential hydrogen storage applications

The synthesis of a Ni-trimesic acid (Ni-BTC) metal–organic framework (MOF) under ambient conditions followed by pyrolysis yields a porous MOF-derived carbon (MDC) doped with elemental Ni, appropriate for hydrogen storage applications. The same methods cannot be used for the synthesis of Mg-BTC MOF and its MDC as the reactivity of Mg towards BTC is not sufficient to prevent competing reactions, and Mg is oxidized to MgO during pyrolysis, preventing hydrogen storage via the formation of MgH2.

Impact of nano-scale cavities on hydrogen storage and retention in yttrium hydride

In situ synchrotron high-energy x-ray diffraction experiments and detailed transmission electron microscopy (TEM) characterization were conducted on as-fabricated and neutron-irradiated yttrium hydrides. The high-resolution synchrotron x-ray diffraction revealed minor α yttrium and major δ yttrium hydride phases in all specimens. Specimens were subject to heat treatments (heating-cooling cycles), and the intensity of α yttrium partially and completely disappeared in as-fabricated and neutron-irradiated specimens, respectively. The disappearance of α yttrium was unforeseen because hydrogen was expected to leave δ phase, causing an increase in α yttrium diffraction peak intensity. This observation indicated a surplus of hydrogen in the specimens where it was odd for hydride-forming early transition metal elements. The subsequent through-focus TEM characterization discovered nanometric cavities in both as-fabricated and neutron-irradiated yttrium hydride specimens for the first time. Two types of cavities were identified as fabrication-caused and irradiation-induced. The fabrication-caused cavities were associated with regions having linear deformation features, interfaces, and inclusions. The irradiation-induced cavities were observed as being formed isolated in the yttrium hydride phase. The presence of such nanometric cavities was considered as potential hydrogen storage pockets where the overall hydrogen storing capacity of yttrium hydride would be enhanced.