Auto-combustion synthesis,structural analysis,and electrochemical solid-state hydrogen storage performance of strontium cobalt oxide nanostructures

Hydrogen storage in transition mixed metal oxides (MMOs) are predicted from their tendency for adsorption-desorption hydrogen. Hydrogen itself requires initial forces pressure for initiation of condensation. MMOs, based on their effective immobilization matrices, are potential nanocatalysts for energy storage. Even various materials are highlighted for hydrogen storage; however, their adsorption capacities are insufficient for real applications. Here we report, for the first time, a novel hydrogen storage MMOs (Sr₂Co₉O₁₄ nanoparticles) potential for physical hydrogen sorption, containing a redox species. This polycrystalline nanoparticle is prepared via a combustion method in the presence of various fuels like glucose, fructose, sucrose, lactose, and maltose. The glucose supports the pure and homogenous formation of Sr₂Co₉O₁₄ nanoparticles consisting the particles less than 100 nm. Interestingly, a maximum discharge capacity of around 950 mA h/g at room temperature has recorded; emphasizing Sr₂Co₉O₁₄ nanoparticles is a potential substrate for hydrogen storage.     

Synthesis of potential nanostructures based on strontium hexaferrite for electrochemical hydrogen storage

Today, the reduction of fossil fuel resources and the increase of their destructive environmental effects are important challenges. One strategy to this problem is application of new sources of energy supply. Hydrogen can play an important role in future energy supplies due to its unique properties such as clean combustion and high energy content relative to mass. In addition, hydrogen is considered as a green energy because it can be produced from renewable sources and is not polluting. The most important issue in hydrogen as a fuel is its storage. Hydrogen must be stored reversibly in a completely safe manner as well as with high storage efficiencies. One of the best ways to store hydrogen is using of new nanostructured adsorbents. In this study, first strontium hexaferrite (SrFe₁₂O₁₉) nanostructures are synthesized by sol-gel auto-combustion method. Then, the samples structure is studied using various techniques. Furthermore, the nanostructures are used as hydrogen storage materials. Using electrochemical techniques, the hydrogen storage properties of the materials are investigated in alkaline media. The obtained electrochemical results show that the maximum hydrogen storage capacity of SrFe₁₂O₁₉ nanostructures is about 3100 mAh/g.     

Novel sonochemical synthesis of Zn2V2O7 nanostructures for electrochemical hydrogen storage

Although utilization of diverse classes of metal oxides as hydrogen storage materials has been reported, but there is still a major need to introduce efficient materials. Herein, mesoporous Zn₂V₂O₇ nanostructures were produced by a new sonochemical method using hydrazine, zinc nitrate, and ammonium vanadate as the starting reagents and then annealed at 700 °C. Prior to annealing, Zn₃V₃O₈ was produced in the presence of ultrasonic waves, whereas in the absence of ultrasonic waves, Zn₂(VO₄)₂ was the major product. In fact, ultrasonic waves interfered with the reaction mechanism and reduced V⁵⁺ to V⁴⁺ and V³⁺. Because of the proper composition and structure of these nanostructures, they were used for electrochemical storage of hydrogen. Storage of over 2899 mAh/g after 20 cycles by flower-like nanostructures revealed their high capability. The results also showed that morphology affects efficiency such that three-dimensional spherical nanostructures had a storage capacity of 2247 mAh/g after 20 cycles.     

Dy3Fe5O12 and DyFeO3 nanostructures: Green and facial auto-combustion synthesis,characterization and comparative study on electrochemical hydrogen storage

Although the technology of hydrogen energy heightened gradually, the application of binary metal oxides as a host for hydrogen sorption has not been widely established. Here we show, with a facial combustion method, the formation of Dy₃Fe₅O₁₂ and DyFeO₃ nanostructures with maximum average particle sizes ranging from 25 to 30 and 16–18 nm, respectively. The physical properties of the samples were served which further reflect in hydrogen storage properties. The discharge capacities of Dy₃Fe₅O₁₂ and DyFeO₃ nanoparticles were obtained at 2000 and 2100 mA h/g, respectively. The hydrogen storage properties were confirmed in their respective current-voltage cycles, prior to chronopotentiometry.     

Superior catalytic effect of titania - porous carbon composite for the storage of hydrogen in MgH2 and lithium in a Li ion battery

A novel nanocomposite (0.2TiO₂ + AC) with two promising applications is demonstrated, (i) as an additive for promoting hydrogen storage in magnesium hydride, (ii) as an active electrode material for hosting lithium in Li ion batteries (surface area of activated carbon (AC): 491 m²/g, pore volume: 0.252 cc/g, size of TiO₂ particles: 20–30 nm). Transmission electron microscopy study provides evidence that well dispersed TiO₂ nanoparticles are enclosed by amorphous carbon nets. A thermogravimetry-differential scanning calorimetry (TG-DSC) study proves that the nanocomposite is thermally stable up to ∼400 °C. Volumetric hydrogen storage tests and DSC studies further prove that a 3 wt% of 0.2TiO₂+AC nanocomposite as additive not only lowers the dehydrogenation temperature of MgH₂ over 100 °C but also maintains the performance consistency. Moreover, as a working electrode for Li ion battery, 0.2TiO₂+AC offers a reversible capacity of 400 mAh/g at the charge/discharge rate of 0.1C and consistent stability up to 43 cycles with the capacity retention of 160 mAh/g at 0.4C. Such cost effective-high performance materials with applications in two promising areas of energy storage are highly desired for progressing towards sustainable energy development.     

Stabilized Li-decoration and enhanced hydrogen storage on reduced graphene oxides

Hydrogen storage properties of Li-decorated graphene oxides containing epoxy and hydroxyl groups are studied by using density functional theory. The Li atoms form Li₄O/Li₃OH clusters and are anchored strongly on the graphene surface with binding energies of −3.20 and −2.84 eV. The clusters transfer electrons to the graphene substrate, and the Li atoms exist as Li⁺ cations with strong adsorption ability for H₂ molecules. Each Li atom can adsorb at least 2H₂ molecules with adsorption energies greater than −0.20 eV/H₂. The hydrogen storage properties of Li-decorated graphene at different oxidation degrees are studied. The computations show that the adsorption energy of H₂ is −0.22 eV/H₂ and the hydrogen storage capacity is 6.04 wt% at the oxidation ratio O/C = 1/16. When the O/C ratio is 1:8, the storage capacity reaches 10.26 wt% and the adsorption energy is −0.15 eV/H₂. These results suggest that reversible hydrogen storage with high recycling capacities at ambient temperature can be realized through light-metal decoration on reduced graphene oxides.     

Mixed-metal Li3N-based systems for hydrogen storage: Li3AlN2 and Li3FeN2

The hydrogen storage systems Li₃AlN₂ and Li₃FeN₂ were synthesized mechanochemically by two different routes. In each case an intermediate material formed after milling, which transformed into Li₃MN₂ (M = Al or Fe) upon annealing. The synthesis route had a measurable effect on the hydrogen storage properties of the material: Li₃AlN₂ prepared from hydrogenous starting materials (LiNH₂ and LiAlH₄) performed better than that synthesized from non-hydrogenous materials (Li₃N and AlN). For both Li₃AlN₂ materials, the hydrogen storage capacity and the absorption kinetics improved significantly upon cycling. Ti-doped Li₃AlN₂ synthesized from LiNH₂ and LiAlH₄ showed the best hydrogen storage characteristics of all, with the best kinetics for hydrogen uptake and release, and the highest hydrogen storage capacity of 3.2 wt.%, of which about half was reversible. Meanwhile, Li₃FeN₂ synthesized from Li₃N and Fe displayed similar kinetics to that synthesized from Li₃N and Fe_xN (2 ≤ x ≤ 4), but demonstrated lower gravimetric hydrogen storage capacities. Li₃FeN₂ displayed a hydrogen uptake capacity of 2.7 wt.%, of which about 1.5 wt.% was reversible. For both Li₃AlN₂ and Li₃FeN₂, doping with TiCl₃ resulted in enhancement of hydrogen absorption kinetics. This represents the first study of a ternary lithium-transition metal nitride system for hydrogen storage.     

Effect of g-C3N4 amount on green synthesized GdFeO3/g-C3N4 nanocomposites as promising compounds for solid-state hydrogen storage

Hydrogen energy is a key role in novel renewable energy production/consumption technologies. Traditional hydrogen energy systems are suffered from low density, high production cost, low efficiency, and storage complications. With the start of solid-state hydrogen storage technology, many of above deficiencies are fulfilled, however, there are several unknown points, particularly in metal oxides, which need more attention. Hydrogen sorption on the layered materials or inside porous materials is a hopeful key to drawbacks for high-performance hydrogen sorption. Hereupon, layered solids with the merit of hydrogen sorption are introduced, for the first time, including “nanostructured bi-metal oxide (BMO)” and “graphitic carbon nitride (CN)”. Perovskites are ceramic and they are hard materials so they could be a favorable candidate for solid-state hydrogen storage. g-C₃N₄ has attractive features including high surface area, chemical stability, small band gap, and low-cost synthesis methods but also has great potential as an electrode material for energy storage capacitors. The main motivation for this study comes from the potential applications for perovskite materials and graphitic carbon nitride for the solid-state hydrogen storage method. The Perovskite type GdFeO₃ nanostructures (as BMO) synthesized through sol-gel approach in front of natural source of Grape juice as both complexing agent and fuel. The experimental scrutinization ascertains an original fabrication of GdFeO₃ (GF) nanostructures in Grape juice at 800 °C, with an approximately uniform nanosized structure of 70 nm on average. The obtained pure GF nanostructures are then utilized for nanocomposite formation based on g-C₃N₄ (CN) with different amounts. The resulting nanocomposites with the ratio of 1:2 from GF:CN perform a preferable hydrogen sorption capacity, in terms of “maximum discharge capacity of 577 mAhg^?1” in 2 M KOH electrolyte. It should be declared that however, the discharge capacity of the nanostructured GF is 188 mAhg^?1. It can be emphasized that these GF/CN nanocomposites can be utilized as hopeful hosts in an electrochemical hydrogen storage setup due to the synergic effect of g-C₃N₄ with essential characteristics in cooperation with BMO nanostructures as acceptable electrocatalysts.     

A direct synthesis of nickel nanoclusters embedded on multicomponent mesoporous metal oxides and their catalytic properties for glycerol steam reforming to hydrogen

Nickel nanoclusters embedded in multicomponent mesoporous metal oxides (Ni–MMOs) are obtained at various support compositions by a single-step synthesis of Ni ion incorporated mesoporous metal oxides (NiO–MMOs) followed by selective reduction of the NiO to Ni metal clusters. The resultant Ni–MMOs catalysts displayed enhanced Ni dispersion with well-developed mesopore structures at various support composition, exhibiting superior catalytic properties when compared to a siliceous SBA-16-supported Ni catalyst prepared by a conventional impregnation method. Glycerol steam reforming conducted at 873 K on 1Ni–2Al₂O₂–2ZrO₂ and 1Ni–2SiO₂–2ZrO₂ catalysts exhibited considerably higher glycerol conversions over the 10 wt%-Ni/SBA-16 catalyst with similar Ni loading amount. This was primarily due to the enhanced Ni dispersion resulting from the direct synthesis process. The multicomponent mesoporous supports also significantly affect product selectivity, favoring higher hydrogen concentration in the product stream. The water–gas shift reaction appears to be positively affected by the 2Al₂O₂–2ZrO₂ and 2SiO₂–2ZrO₂ multicomponent metal oxide matrices, which facilitated the conversion of the CO produced by the glycerol reforming further to additional hydrogen. Direct single-step synthesis of Ni–MMO catalysts was effective in enhancing the dispersion of Ni nanoclusters, as well as variation of the support components of the mesoporous catalyst systems.     

An overview of solar decarbonization processes,reacting oxide materials,and thermochemical reactors for hydrogen and syngas production

Solar decarbonization processes are related to the different thermochemical conversion pathways of hydrocarbon feedstocks for solar fuels production using concentrated solar energy as the external source of high-temperature process heat. The main investigated routes aim to convert gaseous and solid feedstocks (methane, coal, biomass …) into hydrogen and syngas via solar cracking/pyrolysis, reforming/gasification, and two-step chemical looping processes using metal oxides as oxygen carriers, further associated with thermochemical H₂O/CO₂ splitting cycles. They can also be combined with metallurgical processes for production of energy-intensive metals via solar carbothermal reduction of metal oxides. Syngas can be further converted to liquid fuels while the produced metals can be used as energy storage media or commodities. Overall, such solar-driven processes allow for improvements of conversion yields, elimination of fossil fuel or partial feedstock combustion as heat source and associated CO₂ emissions, and storage of intermittent solar energy in storable and dispatchable chemical fuels, thereby outperforming the conventional processes. The different solar thermochemical pathways for hydrogen and syngas production from gaseous and solid carbonaceous feedstocks are presented, along with their possible combination with chemical looping or metallurgical processes. The considered routes encompass the cracking/pyrolysis (producing solid carbon and hydrogen) and the reforming/gasification (producing syngas). They are further extended to chemical looping processes involving redox materials as well as metallurgical processes when metal production is targeted. This review provides a broad overview of the solar decarbonization pathways based on solid or gaseous hydrocarbons for their conversion into clean hydrogen, syngas or metals. The involved metal oxides and oxygen carrier materials as well as the solar reactors developed to operate each decarbonization route are further described.     

Hydrogen release properties of lithium alanate for application to fuel cell propulsion systems

In this paper the results of an experimental study on LiAlH₄ (lithium alanate) as hydrogen source for fuel cell propulsion systems are reported. The compound examined in this work was selected as reference material for light metal hydrides, because of its high hydrogen content (10.5 wt.%) and interesting desorption kinetic properties at moderate temperatures. Thermal dynamic and kinetic of hydrogen release from this hydride were investigated using a fixed bed reactor to evaluate the effect of heating procedure, carrier gas flow rate and sample form. The aim of this study was to characterize the lithium alanate decomposition through the reaction steps leading to the formation of Li₃AlH₆ and LiH. A hydrogen tank was designed and realized to contain pellets of lithium alanate as feeding for a fuel cell propulsion system based on a 2-kW Polymeric Electrolyte Fuel Cell (PEFC) stack. The fuel cell system was integrated into the power train comprising DC-DC converter, energy storage systems and electric drive for moped applications (3 kW). The experiments on the power train were conducted on a test bench able to simulate the vehicle behaviour and road characteristics on specific driving cycles. In particular the efficiencies of individual components and overall power train were analyzed evidencing the energy requirements of the hydrogen storage material.     

Agent-free synthesis of graphene oxide/transition metal oxide composites and its application for hydrogen storage

Graphene oxide (GO) wrapped transition metal oxide composite materials were synthesized by a very simple route without any additional agents and the hydrogen adsorption properties of the materials were investigated. The morphologies of GO/V₂O₅ and GO/TiO₂ were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that single- or few-layered GO sheets wrapped throughout the V₂O₅ and TiO₂ particles. According to X-ray photoelectron spectroscopy (XPS), the C–OH species of GO and the surface-adsorbed oxygen of the transition metal oxide bond together via a dehydration reaction. The wrapping phenomenon of GO causes the enhancement of hydrogen storage capacity at liquid nitrogen temperature (77 K) compared with those of the pristine transition metal oxides and GO. The enhancement of hydrogen storage capacity of GO-wrapped transition metal oxide composite materials results from the existence of interspaces between the transition metal oxide particles and the thin GO layers.     

Hydrogen storage behaviour of Li3N doped with Li2O and Na2O

Mixtures of Li₂O/Li₃N and Na₂O/Li₃N have been investigated for hydrogen storage. When Li₃N is doped with ca. 5 mol% Li₂O and annealed, both binary compounds exist as separate phases as evident from powder X-ray diffraction. Li₂O acts as a spectator in the hydrogen storage reactions and there is no evidence of enhanced Li⁺ or H⁺ mobility. Na₂O (5 mol%) interacts more strongly with Li₃N, leading to the generation of an unidentified phase, which also appears to play no part in the hydrogen storage reactions of the composite system. We conclude that addition of these levels of Li₂O or Na₂O to Li₃N followed by annealing does not improve the hydrogen storage properties of Li₃N.     

The effects of irradiation and high temperature on chemical states in Li2TiO3

In the future D-T fusion reactor, tritium will be bred mainly by the reaction of ⁶Li (n, α) T, as well as ⁷Li (n, n’ α) T in tritium breeding materials. Solid breeding materials will experience harsh conditions under both irradiations by energetic particles (neutron, tritium, helium and self-particles) and high temperature. The interactions of irradiations and high temperature on lithium ceramics will influence tritium breeding ratio (TBR). The changes of chemical states and its effects on release behavior of hydrogen isotopes in deuterium-irradiated Li₂TiO₃ and deuterium-exposed Li₂TiO₃ at high temperature have been investigated. The peak of O-1s shifted to higher binding energy by both irradiation and deuterium exposure, indicating that O-D bonds formed. The amount of O-D bonds enhanced as increase of irradiation fluence and exposure temperature. The main deuterium atoms were trapped by defects for irradiated samples. Annihilation of E-centers was thought to trigger the release of hydrogen isotopes. O-D bonds were the main deuterium trapping sites in deuterium-exposed Li₂TiO₃. Deuterium recovered by detrapping O-D bonds would require higher temperature. Both deuterium-irradiation and deuterium-exposure at high temperature could result in the change of chemical states in Li₂TiO₃. The changes in chemical states had effects on deuterium release. It illustrates that tritium breeding materials in fusion reactor will be modified by both irradiation and high temperature and could result in lower tritium recovery.     

Green solid-state fabrication of new nanocomposites based on La–Fe–O nanostructures for electrochemical hydrogen storage application

Nano-sized La–Fe–O (LFO) structures were fabricated via novel free-solvent and green solid-state route using La (acac)₃. H₂O and Fe (acac)₃ complex precursors. Acetylacetonate (acac) in organometallic complex precursors control nucleation and growth of formed crystals with creation spatial barrier around the cations, and prevent nano-product agglomeration. The mechanism of role of acac has been explained in nanostructure formation. Changing of parameters in synthesis reaction consisting La:Fe molar ratio, calcination time and temperature in turn offer a virtuous control over the nanocomposites size and shape which various compositions of La₂O₃/LaFeO₃, LaFeO₃/La₂O₃ and LaFeO₃/Fe₂O₃ obtained. The as-prepared La–Fe–O nano-products were characterized thorough Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV–Vis, BET and energy dispersive X-ray (EDX) analysis in terms of crystallinity structure, composition, porosity and morphology. Different formed La–Fe–O nanostructures were evaluated for electrochemical hydrogen storage capacity through chronopotentiometry technique in stable current (1 mA). The achieved La–Fe–O nanoparticles could be applied as a favorable candidate active material for electrochemical hydrogen storage. Optical, magnetic and reducible characteristics of La–Fe–O nanostructures have positive effect on electrochemical hydrogen storage capacity. It was found out that the LaFeO₃/Fe₂O₃ nanocomposites have the best electrochemical hydrogen storage performance due to oxidation-reduction process of Fe²⁺/Fe³⁺ components which can help to charge-discharge process of hydrogen to increase the storage capability to 790 mAhg^?1 after 20 cycles. Also, the mixed metal oxides illustrate advanced discharge capacity than other binary oxides.     

Insight into effects of graphene and zinc oxide in Li4Ti5O12 as anode materials for Li-ion full-cell battery

Programmable design of nanocomposites of Li₄Ti₅O₁₂ (LTO) conducted through hydrothermal route in the presence of ethylenediamine as basic and capping agent. In this work, effect of ZnO and Graphene on the Li₄Ti₅O₁₂ based nanocomposites as anode materials investigated for Li-Ion battery performances. The full cells battery assembled with LTO based nanocomposites on Cu foil as the anode electrode and commercial LMO (LiMn₂O₄) on aluminum foil as cathode electrode. X-Ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), along with Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission electron microscopy (TEM) images was applied for study the composition and structure of as-prepared samples. The electrochemical lithium storage capacity of prepared nanocomposites was compared with pristine LTO via chronopotentiometry charge-discharge techniques at 1.5–4.0 V and current rate of 100 mA/g. As a result, the electrode which is provided by LTO/TiO₂/ZnO and LTO/TiO₂/graphene nanocomposites provided 765 and 670 mAh/g discharge capacity compared with pristine LTO/TiO₂ (550 mAh/g) after 15 cycles. Based on the obtained results, fabricated nanocomposites can be promising compounds to improve the electrochemical performance of lithium storage.     

Meritorious spatially on hierarchically Co3O4/MoS2 phase nanocomposite synergistically a high-efficient electrocatalyst for hydrogen evolution reaction performance: Recent advances & future perspectives

Hydrogen is zero-emission fuel production for a clean environment as alternative effective the energy source is still moreover, an effective challenge in near future due to the lack of efficient and inexpensive catalysts. An efficient electrocatalysts structure having logical design which holds a paramount significance for the hydrogen evolution reaction (HER) but rarely noble metal Pt-like activity achieved by the transition metal oxides electrocatalysts based on oxides matured and cooperative with coupling metal oxides could be considered as a desired substitute electrocatalysts to change Pt/C based nano composite materials. Herein, un-noble the metal oxides of hetero structure consisting of Co₃O₄/MoS₂ based-electrocatalysts nanocomposite material. The desirable out-comes show that Co₃O₄/MoS₂ composite material providing extraordinary efficient HER kinetics activity in different experimental designs. The Co₃O₄/MoS₂ based electro-catalyst increases the best activity of HER kinetics performance especially measured in 1 M KOH solution condition and offers an influential interfacing engineering strategy at very minute over potential of 348 mV evaluated and small Tafel slopes 46 mV/dec for HER performance. This work elucidates interest for efficient electrocatalysts for a broader range of scalable applications in the development of renewable energies, the functional materials such as solar cells, lithium sulphur-batteries and energy chemistry advancing.     

Effect of metal atom substitutions in Li based hydrides for hydrogen storage

By using density functional theory and the full-potential linearised augmented plane wave method, the effect of alkali (AM) and transition metal (TM) atom substitutions in Li based hydrides (Li₇XH₈ X (AM) = Na, K, Rb and X (TM) = Ti, V, Cr) was investigated, by studying their formation energies and electron properties, aiming at improving hydrogen storage performance. The calculated formation energy values indicate that there is a gradual degradation in stability due to alkali substitutions from Na to Rb and to transition metal substitutions from Ti to Cr in Li₇XH₈. The found degradations of stability in Li₇XH₈ were better compared concomitantly with corresponding gravimetric hydrogen storage variations. The less stable phase with least variation in gravimetric hydrogen storage was found to be Li₇CrH₈ among all alkali and transition metal atom substitutions. The density of states and the electron density support our observations.     

Mechanism of vacuum-annealing defects and its effect on release behavior of hydrogen isotopes in Li2TiO3

Li₂TiO₃ is one of the most promising candidates among solid breeder materials. However, defects introduced into Li₂TiO₃ will act as the strong trapping sites for tritium. In the present study, mechanism of vacuum-annealing defects and its effect on release behavior of hydrogen isotopes in Li₂TiO₃ were investigated by means of X-ray diffraction, Raman spectroscopy, electron spin resonance and thermal desorption spectroscopy. The color of samples becomes dark blue and the defects were found to be introduced into Li₂TiO₃ when annealed in vacuum. This color change suggests the change from Ti⁴⁺ to Ti³⁺ due to decrease in oxygen content. The color recovers to white again after annealing in air. X-ray diffraction and Raman spectroscopy results indicate that there are no modifications on Li₂TiO₃ crystal phases, but on crystallinity. The main vacuum-annealing defects are E-centers and no other obvious types of defects were observed from electron spin resonance. Based on the experimental results, the production of defects by annealing in vacuum should be satisfied to the following conditions: (1) Li₂TiO₃ has been exposed in air more than 1 day; (2) Li₂TiO₃ must be annealed at the temperature higher than 300 °C; (3) Li₂TiO₃ should be annealed in vacuum lower than 10 Pa. E-centers formed under vacuum-annealing processes have considerable effects on release behavior of hydrogen isotopes investigated by thermal desorption spectroscopy and further should be considered in future fusion reactor. The present work gives some suggestions for future fusion reactors: (1) Li₂TiO₃ should be preserved in vacuum or kept from water vapor; (2) Li₂TiO₃ should be annealed at high temperature to remove the adsorbed water before loading into the facility, and must be finished within two days to avoid defects coming from reduction; (3) Li₂TiO₃ should be improved by adding more oxygen or other elements to refrain from defects introduced by reduction reaction.     

Enhancement of hydrogen binding affinity with low ionization energy Li2F coating on C60 to improve hydrogen storage capacity

The capacity of hydrogen storage for solid sorbents depends strongly on the binding affinity between hydrogen molecules and solid sorbents. By coating C₆₀ with a low ionization energy material (Li₂F), we obtained an enhanced binding energy and an improved electron transfer between H₂ and hosts. With the first-principles calculations and charge analysis, we found that the orbital interactions play a dominant role in this system and eventually 68H₂ molecules can be stably stored by a C₆₀(Li₂F)₁₂ cluster with a binding energy of 0.12 eV/H₂. The resulting gravimetric and volumetric density of H₂ stored on C₆₀(Li₂F)₁₂ are 10.86 wt% and the 59 g/L through calculations. Our investigation indicates that metals or metal clusters with lower ionization energies would be beneficial to enhance interactions between hydrogen and hosts, and thus, the hydrogen storage capacities for solid sorbents can be greatly improved.