Reversible Hydrogen Storage Research Articles

Two-dimensional BC6Be: Reversible, high-capacity hydrogen molecule storage material predicted by first-principles calculations

The research was conducted to discover a material that can efficiently and effectively store hydrogen at appropriate conditions. Specifically, its focus was on examining the hydrogen storage properties of unaltered single-layer BC6Be using density functional theory techniques. The results revealed an intriguing phenomenon: H2 molecules spontaneously adhere to the BC6Be monolayer, exhibiting average adsorption energy spanning between −0.272 and −0.380 eV. Importantly, this adsorption is driven by physisorption, lacking any chemisorption bonding between the H2 molecule and the BC6Be surface, regardless of the interaction site. Noteworthy is the remarkable gravimetric and volumetric hydrogen storage capacities of the monolayer BC6Be, registering at 11.63 wt% and 108.5 g/L, respectively. Comparatively, the desorption temperature (TD) stands notably higher at around 247.15 K when juxtaposed with hydrogen's critical point (33.25 K). AIMD simulations were conducted to substantiate the results, confirming the adsorption of 12H2 molecules on BC6Be and verifying the system's stability. Overall, the findings of this work have shown the potential of the BC6Be monolayer as a highly promising material that offers efficient, reversible, and substantial hydrogen storage capabilities within real-world scenarios.

Lithium-modified B3C2P3 monolayer as a promising medium for reversible hydrogen storage

Although two-dimensional (2D) materials have been extensively studied as hydrogen storage media, the search for 2D materials with high hydrogen storage capacity and reversible hydrogen storage properties at room temperature remains challenging. In this context, B3C2P3 monolayer with Li modification is studied systematically by first-principles calculation. We find that Li-modified B3C2P3 monolayer can achieve a high hydrogen storage capacity of 8.99 wt% with an average adsorption energy of −0.23 eV/H2. Three of the H2 molecules are adsorbed around the Li atom, while the fourth H2 molecule is adsorbed above the buckled P atom due to the constricted space around the Li atom. Not only metal Li atoms but also the buckled substrate plays an important role in hydrogen adsorption, indicating that buckled 2D materials are more interesting and promising in hydrogen storage than flat 2D materials. The average desorption temperature (TD) calculated by van't Hoff formula is 293.84 K, which is very close to room temperature. In addition, at room temperature, the structure of hydrogen adsorption is stable at a low pressure of 3.21 MPa, suggesting a broad application prospect of in reversible hydrogen storage.

Study of dual osmium and boron co-doped SWCNTs for reversible hydrogen storage

The dual osmium/boron doped/co-doped armchair single walled carbon nanotubes (SWCNTs) have been explored for hydrogen storage applications via ab-initio method. We thoroughly screen dual osmium/boron doping at two different opposite positions in SWCNTs and analyze bond distances, binding energy, band gaps, electrophilicity, density of states, adsorption energies, adsorption enthalpy, Gibbs free energy and storage capacity. The results summit Osmium doped CNTs as hopeful nominees for hydrogen storage applications. The findings indicates that Osmium atoms doping in opposite sides of CNT along with boron atoms at ortho position (2Os-2BCNT) show 1.95 wt% gravimetric hydrogen storage capacity at 298.15 Kelvin temperature and 1 atm pressure. Furthermore, the feasibility of doped SWCNTs have been explored for storage applications by performing average Van't Hoff desorption temperature calculations and molecular dynamics simulations for 2Os-2BCNT at maximum desorption temperature and 1 atm pressure.

Me–C8B5: A novel two-dimensional carbon boride as reversible hydrogen storage material with high capacity

In this work, we predict a new two-dimensional metallic carbon-boron material, named Me–C8B5, which is composed of octagons, pentagons and hexagons. By DFT calculation, we examine the efficacy of hydrogen storage in alkali and alkaline-earth metals modified Me–C8B5 structures. Our findings reveal that these metals exhibit a robust affinity for the Me–C8B5 substrate, characterized by substantial binding energies, thereby mitigating the tendency to form clusters. In particular, the hydrogen storage capacity for Li, Na, Mg and Ca modified Me–C8B5 reach 6.87 wt%, 7.60 wt% and 5.74 wt% and 9.51 wt%, respectively, higher than the DOE requirement of 4.5 wt%. The results of relative energy reveal that the Li-modified system exhibits more appropriate pressure (8.4 bar) and temperature (370 K) for maintaining stable hydrogen storage. Notably, the suitable average desorption temperatures coupled with the stability exhibited in AIMD simulations indicate that Me–C8B5 scaffolds modified with metals Li, Na, Mg, and Ca may possess viable practical applications in the realm of reversible hydrogen storage. These outcomes are anticipated to stimulate the pursuit and continued refinement of novel, superior two-dimensional materials for hydrogen storage.

Mxene-supported NbVH nanoparticles as efficient catalysts for reversible hydrogen storage in magnesium borohydride

Bimetallic niobium vanadium hydride nanoparticles (NbVH NPs) anchored on Ti3C2 were synthesized using a facile ball milling method as an effective catalyst for the dehydrogenation kinetics and reversibility of Mg(BH4)2. It was found that the onset dehydrogenation temperature of the Mg(BH4)2 + 30NbVH NPs@Ti3C2 composite was 105.7 °C and released 9.07 wt% of hydrogen at 330 °C, while undoped Mg(BH4)2 only released 4.2 wt% of H2 from 248 °C to 330 °C. Additionally, the Mg(BH4)2 + 30NbVH NPs@Ti3C2 composite achieved remarkable hydrogen release of over 9.44 wt% at a temperature as low as 230 °C, indicating unexpected dehydrogenation kinetics. In the reversible hydrogen desorption tests, Mg(BH4)2 + 30NbVH NPs@Ti3C2 released 5.98 wt% of H2 in the 2nd cycle at 250 °C and maintained a reversible capacity of 4.35 wt% after 10 cycles, demonstrating a remarkable enhancement in reversibility. The enhancement in the dehydrogenation kinetics of Mg(BH4)2 could be attributed to the greatly reduced activation energies from 343 kJ·mol−1 and 138.3 kJ·mol−1 to 103.7 kJ·mol−1 and 124 kJ·mol−1. Investigations on the evaluation of catalyst and Mg(BH4)2 during reversible hydrogen storage have revealed that NbVH NPs actually acted as a “bidirectional hydrogen pump”, facilitating both the hydrogen release and uptake from Mg(BH4)2. This strategy of multi-component hydrides may show a new way to design effective catalysts for solid-state hydrogen storage materials.

Ultrahigh-capacity reversible hydrogen storage in BN-biphenylene under environmental conditions

Ultrahigh-capacity reversible hydrogen storage in BN-biphenylene under environmental conditions

Does the Oxygen Functionality Really Improve the Thermodynamics of Reversible Hydrogen Storage with Liquid Organic Hydrogen Carriers?

Liquid organic hydrogen carriers (LOHCs) are aromatic molecules that are being considered for the safe storage and release of hydrogen. The thermodynamic properties of a range of aromatic ethers were investigated using various experimental and theoretical methods to assess their suitability as LOHC materials. The absolute vapour pressures were measured for benzyl phenyl ether, dibenzyl ether and 2-methoxynaphthalene using the transpiration method. The standard molar enthalpies and entropies of vaporisation/sublimation were derived from the temperature dependence of the vapour pressures. The combustion energies of benzyl phenyl ether and dibenzyl ether were measured using high-precision combustion calorimetry, and their standard molar enthalpies of formation were derived from these data. High-level quantum chemical calculations were used to calculate the standard molar enthalpies of formation in the gas phase for benzyl phenyl ether, dibenzyl ether and 2-methoxynaphthalene. The latter values agreed very well with the experimental results obtained in this work. The thermodynamic properties of the hydrogenation/dehydrogenation reactions in liquid phase in LOHC systems based on methoxy–benzene, diphenyl ether, benzyl phenyl ether, dibenzyl ether and 2-methoxynaphthalene were derived and compared with the data for similarly structured hydrogen carriers based on benzene, diphenylmethane, 1,2-diphenylethane, 1,3-diphenylpropane and naphthalene. The influence of the oxygen functionality on the thermodynamic properties of the hydrogenation/dehydrogenation reactions was evaluated.

First-principles investigation of Irida-graphene decorated with alkali metal for reversible hydrogen storage

Irida-graphene (IG) is a novel stable graphene allotrope, which exhibits metallic property. Based on first principles calculations, the potential of IG decorated with alkali metal atoms in reversible hydrogen storage has been investigated. Compared with graphene, IG has stronger binding on alkali metal atoms. For Li, Na, and K decorated IG, the polarization mechanism plays a crucial role in the adsorption of H2, the adsorption energies of H2 are −0.286, −0.209 and −0.183 eV/H2, and the hydrogen gravimetric densities can reach 7.1, 7.8 and 5.2 wt%, respectively, indicating that K decorated IG is not suitable as a hydrogen storage medium. The desorption temperatures calculated are 365 K and 267 K for stored H2 on Li/IG and Na/IG, respectively, and ab inito MD simulation suggest that Li/IG and Na/IG are stable at high temperature, thus Li and Na decorated IG have the potential application for reversible hydrogen storage.

Grid variability and value assessment of long-duration energy storage under rising photovoltaic penetration: Evidence from Japan

Using high-resolution grid power balance and market data, this work investigates the effects of rising solar photovoltaic generation on the variability of large-scale net grid load and spot prices, and conducts an analysis of the potential balancing profits of various grid-scale energy storage systems. Analysis results show the correlation between PV (photovoltaic) generation and electricity demand has been identified as a significant factor influencing spot price value. As PV penetration increases, the value of spot prices experiences a notable decline, with values declining to nearly zero when the share of hourly PV generation surpasses 70 %. The volatility of electricity spot prices has a substantial impact on utilization rates and economic profits of energy storage systems employed for grid energy balancing. Despite the lower roundtrip efficiency, reversible hydrogen storage system can offer positive benefits. The longer storage duration offers the advantage of capturing greater dispatch profits by exploiting price differences over extended periods. Considering the time-varying nature of spot prices, the rated power capacity of the storage system plays a significant role in determining its utilization rates. The larger rated charging and discharging ability of the storage system allows for more effective utilization of price fluctuations, resulting in greater profitability.

Density and speed of sound measurements of aqueous solutions of potassium formate, potassium bicarbonate and their mixtures

Potassium formate and potassium bicarbonate are currently subject of research in a variety of new potential technical applications. One example of this is the use of the mixture of both salts in solution as a reversible hydrogen storage system and thus as a potential renewable energy carrier. In order to develop these new technologies, knowledge of the thermophysical properties of the individual salt solutions and mixtures is essential. Due to the limited data available in literature, which are only available for the single salt solutions, measurements of density and speed of sound as well as mathematical correlations based on the data were carried out in order to predict the behaviour of the salt solutions as a function of concentration and temperature. Good approximation equations were found for both properties, which agree with the existing data in the literature and result in deviations well below 1 % over wide concentration and temperature ranges. The large number of measurements, the clear trends in the results and the good agreement with existing data from the literature allow to assume that reliable predictions of concentration, and thus degree of hydrogen charging, can be realized utilizing density measurements. With the help of this fundamental research, it will not only be possible to investigate the newly discussed applications in more detail in the future, but also enable more precise design calculations, models and simulations. In addition, material properties that result from the measured variables or are related to them, such as thermal expansion or isentropic compressibility, can be analysed.

Promoting Catalytic Performance of Metal Hydrides for Reversible Hydrogen Storage in N-ethylcarbazole by Electronic Structure and Hydrogen Chemical Potential Tuning

Promoting Catalytic Performance of Metal Hydrides for Reversible Hydrogen Storage in N-ethylcarbazole by Electronic Structure and Hydrogen Chemical Potential Tuning

Transition metal atoms (TM = Sc, Ti, V, Cr, and Mn) decorated PBCF-graphene as a possible reversible hydrogen storage material: A DFT-D2 investigation

One of the most pressing concerns for hydrogen energy development is the identification of new compounds with high capacity and effective reversibility for hydrogen storage. This study employs a unique all-sp2 hybridized two-dimensional (2D) carbon allotrope inspired by graphene synthesis using benzene as a precursor. This 2D carbon allotrope is a polybutadiene cyclooctatetraene framework known as PBCF-graphene. This work investigated the electrical and structural properties of transition metal-decorated PBCF-G (TM-PBCF-G) for H2 adsorption using the DFT-D2 technique. Next, the most stable structures' H2 uptake and storage were examined. According to the results, the hollow site in the hexagonal ring's center is the most stable location for all TM decorations. Additionally, PBCF-G which has been adorned with Sc and Ti has the highest energy stability, with Eb values of −7.599 and −8.380 eV, respectively. The analysis of H2's adsorption behavior on TM-PBCF-G indicates that Cr-PBCF-G has the greatest adsorption energies (−0.701 eV), and that H2's horizontal direction has a greater stability energy. Upon gradually adding more H2 molecules to pristine and Cr-PBCF-G, it is shown that these materials can store 4 and 17H2 molecules, respectively, with average adsorption energies of −0.102 and −0.167 eV/H2, and corresponding H2 storage capacities of 5.26 and 9.10 wt%. These results demonstrate the potential of Cr-PBCF-G as a viable H2 storage material in the future.

Optimization of V-Ti-Fe hydrogen storage alloy based on orthogonal experiments

Vanadium-based solid solution hydrogen storage alloys have attracted much attention because of their high hydrogen capacity, mild hydrogen absorption- desorption conditions, and high safety. However, the V-Ti-Fe alloys, developed at low cost, have a relatively low effective capacity and is unsuitable for practical production. In this work, (VxFe100-x)100-yTiy-z%Ce (x=0.83,0.85,0.87; y=16,18,20; z=1,2,3) alloys are designed by orthogonal method to investigate the effect of compositions on the microstructure and hydrogen storage properties. It is shown that the effective hydrogen capacity and desorption plateau pressure of the (VxFe100-x)100-yTiy-z%Ce alloy are related to multiple factors, such as lattice constants, tetrahedral interstitials of the BCC and BCT phases, electron concentration and Vickers hardness. The optimized alloy (V87Fe13)82Ti18-1 %Ce based on the orthogonal experiments shows a reversible hydrogen storage capacity of 2.17 wt% and a desorption plateau pressure of 0.373 MPa at 70°C. The reversible hydrogen capacity of (V87Fe13)82Ti18-1 %Ce is superior to most V-Ti-Fe alloys.

Unveiling reversible hydrogen storage mechanism for the 2D penta-SiCN material

The promise of using 2D materials for hydrogen storage has broad prospects, ascribe to their significant specific surface area and lightweight properties. In this work, the hydrogen storage capability and reversible storage mechanism of 2D penta-SiCN material are investigated based on the first-principles computational method. Thermal stability of penta-SiCN is calculated by the ab-initio molecular dynamics (AIMD) simulation and root-mean-square displacement (RMSD) algorithm. It has been found that penta-SiCN is thermodynamically stable even after adsorbing hydrogen molecules. Taking into account the benchmarks of average and continuous adsorption energies of the adsorption systems, a pristine 2 × 2 × 1 penta-SiCN substrate has the ability to adsorb up to 26H2 molecules, which results in a maximum hydrogen storage capacity of 10.80 wt%. According to the semi-empirical calculation method that based on the thermodynamic analysis, the penta-SiCN adsorption system has a high reversible hydrogen storage capacity of 9.57 wt% within the adsorption and desorption application working conditions. The results proposed in this study demonstrates that penta-SiCN exhibits considerable promise for hydrogen storage with its substantial hydrogen storage capacity, exceptional reversibility, and eco-friendly characteristics.

Exploring microstructure variations and hydrogen storage characteristics in TiVNbCrNi high-entropy alloys with different Ni incorporation

In recent years, high-entropy alloys (HEAs), as a novel class of hydrogen storage materials, have been deemed highly promising due to their extensive compositional tunability and the unique high entropy effects. This study aims to enhance the comprehensive hydrogen storage performance of the TiVNbCr-based HEA by introducing Ni. The effects of Ni addition on the microstructural evolution of the alloy and its impact on activation properties, hydrogen absorption and desorption kinetics, thermodynamics, and cycling performance under the complex physicochemical environment of multiple principal elements was systematically investigated. The findings indicate that Ni addition shortens the activation incubation period of the alloy but more Ni reduces the intrinsic hydrogen absorption kinetics. In the Ti25V30Nb10Cr33Ni2 alloy, a high reversible hydrogen storage capacity of up to 2.2 wt% at room temperature was achieved, surpassing most of the currently reported body-centered cubic (BCC)-structured high-entropy hydrogen storage alloys. Furthermore, the influence of Ni on the alloy's hydrogen desorption kinetics and cycling hydrogenation performance was studied. Results from 110 cycles of testing reveal that the introduction of Ni-induced Laves phases can act to relax stress, thereby reducing strain accumulation during the hydrogen absorption and desorption cycling process. This could provide guidance for the design of high-entropy hydrogen storage alloys with extended cycling lifetimes.

Computational investigation of NLi4-cluster decorated phosphorene for reversible hydrogen storage

The use of lithium-decorated phosphorene for hydrogen storage is significantly limited due to metal aggregation on substrates. Despite considerable research and effort in the literature to address this issue, no one has succeeded in enhancing the capacity of phosphorene through metal atom decoration. Based on density functional theory (DFT) and AIMD simulations, superalkali NLi4-decorated black phosphorene monolayer is developed as a new hydrogen storage solid-state material. Our results show that the NLi4-cluster exhibits a significant binding energy of −3.18 eV when attached to one side of the phosphorene on a stable site, indicating a strong affinity between the NLi4-cluster and phosphorene surfaces. Moreover, 2(NLi4)@phosphorene can store up to 30H2 molecules with a suitable average hydrogen adsorption-energy and a maximum hydrogen storage capacity of 6.8 wt%. Using the van't Hoff equation and increasing the pressure, we find that the desorption temperature is higher than the critical point for hydrogen. AIMD simulations at different temperatures demonstrate the thermal stability of the hydrogenated 2(NLi4)@phosphorene and the H2 desorption process. The findings of the present study suggest the potential utilization of the 2(NLi4)@phosphorene adsorptive material for hydrogen storage applications.

Computational Investigation of a Reversible Energy Storage Medium in g-B5N3 Decorated by Lithium.

Graphene-like materials in two dimensions hold great promise for energy storage and transformation applications owing to their distinctive features, such as lightweight composition, porous geometry, etc. Among these materials, a recently discovered unit known as g-B5N3 has demonstrated high performance in energy storage and transformation. In our efforts to enhance its applicability in adsorbing energy gases, we propose a novel composite structure by decorating Li atoms on the surface of pristine g-B5N3. The electronic properties of this composite have been comprehensively investigated using a first-principles method. Our findings reveal that the added Li atoms can be securely anchored on the g-B5N3 with an adsorption energy of -3.01 eV. Furthermore, the Li atom transfers its partial 2s electrons to the g-B5N3, exhibiting considerable electropositivity. These metallic sites effectively polarize the adsorbed H2 molecules, enhancing the mutual electrostatic interactions. Each primitive cell of Li-doped g-B5N3 can adsorb up to 13 H2 molecules, resulting in a storage capacity up to 6.3 wt %. This capacity significantly surpasses the goal of 4.5 wt % set by the U.S. Department of Energy. Furthermore, the typical adsorption energy of -0.209 eV per molecule of H2 aligns with the energy range suitable for reversible hydrogen storage. This study underscores the potential of Li-doped g-B5N3 for energy gas adsorption, shedding light on further advancements in this field.

Sodium alanate in-situ doped with Ti2C MXene with enhanced hydrogen storage properties

NaAlH4 is a reversible hydrogen storage material and has attracted great attention recently. However, the application of NaAlH4 in hydrogen storage still has great difficulties. In this study, 2D MXene Ti2C-doped NaAlH4 samples were prepared in-situ by reaction ball milling of NaH under moderate condition. TPD measurement results show that all the as-prepared samples exhibit good thermodynamic performance except for the sample doped with 1 wt% Ti2C. And DSC analysis results show that at the heating rate of 5 K/min, the first and second dehydrogenation peak temperatures of the sample doped with 7 wt% Ti2C were 127.1 °C and 150.6 °C respectively, which are 57.4 °C and 123.6 °C lower than those of pure NaAlH4 (after ball milling), respectively. Meanwhile, NaH/Al-7 wt.% Ti2C sample displays a superior kinetics behavior. Isothermal hydrogen evolution curves show that NaH/Al-7 wt.%Ti2C released 5.21 wt% H2 within 30 min at 150 °C and then absorbs 5.2 wt% H2 in 90 s at 120 °C. Even at a lower temperature of 80 °C, the sample still absorbed 4.71 wt% H2 within 60 min. In addition, almost no release capacity attenuation was observed for NaH/Al-7 wt.%Ti2C after 10 hydrogen absorption/desorption cycles. The improvement of the hydrogen storage properties can be ascribed to the high reactivity of NaAlH4 produced in situ and catalysis of lamellar Ti3+/0 species formed by the reduction of high valent Ti in Ti2C during ball milling.

Enhancing reversible hydrogen storage performance of 2LiBH4–MgH2 via in-situ building heterogeneous nucleation sites

Enhancing reversible hydrogen storage performance of 2LiBH4–MgH2 via in-situ building heterogeneous nucleation sites

Effect of palladium nanoparticle decoration on hydrogen storage capacity of β12-borophene

In this study, DFT calculation is performed to systematically investigate the effect of palladium nanoparticle decoration on the hydrogen storage capacity of β12-borophene. The optimized structures of Pd4@β12-borophene indicated that Pd4 is strongly bonded to β12-borophene with a binding energy value of −3.64 eV, exhibiting good structural and thermodynamic stability. The binding energy of the H2 molecule over β12-borophene enhanced by Pd4 decoration ranges from −0.108 eV to −0.234 eV/H2 and can chemically bond up to 5 hydrogen molecules which was in the acceptable range for reversible hydrogen storage. Slight H2 spillover was observed on Pd4 decorated β12-borophene. Electronic analysis showed that the metallicity of borophene slightly increases after Pd4 decoration. The electronegativity of the Pd4 atoms can stimulate the adsorbed H2 polarization, further increasing the interactions among them. DOS analysis confirmed the charge transfer and interactions between H and Pd atoms which favors hydrogen adsorption of the system.