Reversible Hydrogen Storage Material Research Articles

Investigation of TiCr Hydrogen Storage Alloy

A new reversible hydrogen storage material, based on TiCr metal alloy, is proposed. Cr and Ti were mixed and melted in a final atomic ratio of 1,78. Chemical-physical characterisations, in terms of XRD and SEM-EDX, were performed. The quantification of Laves phases was performed through Rietveld refinements. The atomic Cr/Ti ratio was determined by EDX analysis and 1,71 was obtained. The H2 sorption/desorption measurements by Sievert apparatus were carried out. After different tests varying temperature and pressure, a protocol measurement was established; and a H2 sorption value of 0,4 wt% at 200 °C/10 bar with a fast kinetic at 5 bar (Dwt% of about 0,3 wt%) were obtained. Hydrogen desorption measurements performed in the same conditions of T confirmed a totally reversible trend. A confirm of metal hydride formation was recorded by XRD, in fact, comparing X-Ray patterns before and after volumetric tests a notable difference was recorded.

Li decorated Be3C2 as light-weight host material for reversible hydrogen storage

Deficiency of appropriate host materials with high gravimetric density for hydrogen storage impedes the development of hydrogen economy and its downstream application, i.e., hydrogen fuel battery. Within the framework of density functional theory, we investigate systematically the performance of Li decorated Be3C2 for hydrogen adsorption and reversible storage. We find that Li atoms forms strong bond with the light-weight Be3C2 substrate without the issue of agglomeration, where dispersive decoration of Li on Be3C2 is calculated to be more energetically than Li metallic clusters. As for Li doped Be3C2 system, a maximum gravimetric hydrogen density of 10.79 wt% could be reached. Such high-capacity benefits from the light-weight of the host and its strong binding to H2 molecules, in which both polarization and electronic hybridization mechanism play a significant role. Hydrogen storage under different pressure and temperature has also been discussed based on thermodynamic analysis and a practical capacity of 9.27 wt% could be expected under more realistic operation of hydrogen fuel battery (stored at 30 atm/25 °C and released at 3 atm/100 °C). Favorable hydrogen adsorption capability and desired storage/release dynamic performance endows Li decorated Be3C2 with promising applications in hydrogen energy storage field.

Nanostructured carbons modified with nickel as potential novel reversible hydrogen storage materials: Effects of nickel particle size

Fil: Carraro, Paola Maria. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Centro de Investigacion y Tecnologia Quimica. Universidad Tecnologica Nacional. Facultad Regional Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Fisica Enrique Gaviola. Universidad Nacional de Cordoba. Instituto de Fisica Enrique Gaviola; Argentina

Identification of Intermediates during the Hydration of Na8[AlSiO4]6(BH4)2: A Combined Theoretical and Experimental Approach.

Tetrahydroborate sodalites have been discussed as possible materials for reversible hydrogen storage. In order to access the suitability of Na8[AlSiO4]6(BH4)2, its reaction with water was investigated theoretically and experimentally. Density functional theory (DFT) calculations at the generalized gradient approximation (GGA) level were performed to identify the reaction intermediates. We compared experimental IR spectra and 11B NMR chemical shifts with theoretical results for selected molecules in the sodalite cage. Furthermore, the free energies of reaction of the intermediates with respect to Na8[AlSiO4]6(BH4)2, gaseous water, and molecular hydrogen at different temperatures were also calculated.

Highly synergetic catalytic mechanism of Ni@g-C3N4 on the superior hydrogen storage performance of Li-Mg-B-H system

Li-Mg-B-H system with the composition of 2LiBH4-MgH2 is one of the most promising reversible hydrogen storage materials because of the extremely high hydrogen storage capacity (11.5 wt%). Yet, sluggish kinetics with high desorption temperature (~ 400 °C) hindered its practical applications. Herein, a highly efficient catalyst of nanoNi@g-C3N4, comprised of transition metal nanocatalyst and carbon-based nonmetal material, was designed and fabricated to dramatically reduce its initial hydrogen desorption temperature to as low as ~105 °C, and eliminate induction period between the two dehydrogenation steps of 2LiBH4-MgH2 by reducing the activation energy for the dehydrogenation of LiBH4 from 200±6 to 126±7 kJ/mol. Multiple postmortem analyses revealed that the in situ formed MgNi3B2 NPs and the H+ defects on g-C3N4 play the key role in synergically enhancing the hydrogen reversible desorption/absorption kinetics at low temperature: 1) in situ formed MgNi3B2 acts as nucleation center of MgB2 and leads to an excellent catalytic effect to accelerate the dehydrogenation kinetics of 2LiBH4-MgH2; 2) the H+ defects on g-C3N4, will interact with the H– in LiBH4 to trigger the release of H2 at low temperature and destabilize LiBH4 and MgH2 to form Li3N and Mg3N2 respectively for the high electronegativity of N: 3) these in situ formed intermediates of Li3N and Mg3N2 will be readily rehydrogenated as highly reversible Mg(NH2)2 and LiH. This novel transition metal and g-C3N4 catalytic composites could provide alternative insights into designing nanosized catalytic hydrogen storage system with low desorption temperature and high capacity for hydrogen-fueled applications.

Theoretical insight into the BH3·HCN adsorption on the Co(100) and Co(110) surfaces as hydrogen storage.

Fifteen configurations and adsorption energies of the adsorption sites of BH3∙∙∙HCN on Co(100) and Co(110) surfaces were investigated using the density functional theory. The results show that after BH3∙∙∙HCN is adsorbed, although there is no general behavior for the H∙∙∙H distances, the adsorption energies of BH3∙∙∙HCN are always far stronger than those of H2 on Co surfaces, suggesting that the dihydrogen-bonded complex, one kind of prospective material for reversible hydrogen storage, can be tightly adsorbed on the surfaces of metals. Thus, the attempts to store the significant amounts of H2 can be successful by the way that the dihydrogen-bonded complexes are adsorbed on the surfaces of metals. The stability and binding mechanism was analyzed by the Mulliken charge population and reduced density gradients (RDGs) methods. Graphical Abstract BH3···HCN adsorption on Co surface.

Metal organoclays with compacted structure for truly physical capture of hydrogen

Truly reversible capture of hydrogen was achieved at ambient conditions on Pd-loaded organo-montmorillonites obtained by photo-addition of different thiols on propargylated-TRIS cations already grafted on the clay surface. TEM insights showed that more than 90% of Pd0 incorporated occur as 0.3–0.5nm subnanoparticles (PdSNPs). XPS and NMR analyses revealed simultaneous strong S:Pd0 and O:Pd0 interactions that ”cement” the organic moiety around PdSNPs. The significant decrease in porosity suggests a compacted structure that impedes not only metal aggregation, but also hydrogen diffusion in the metal bulk. Thus, hydrogen appears to adsorb mainly via physical condensation around PdSNPs. These thiol-clay matrices showed hydrogen surface affinity factors of up to 0.51mmolm−2 at ambient temperature and pressure. This is higher than those reported for much more sophisticated materials. DSC measurements showed very low desorption heat between 20 and 80°C. Hydrogen release was achieved merely under vacuum or slight heating starting from 40°C and was almost completed up to 85°C. This provides a proof of concept of truly reversible capture of hydrogen for concentration and/or storage purposes. Such a performance has never been achieved at ambient temperature and pressure. These findings open new prospects to develop low-cost materials for reversible hydrogen storage without energy and safety constraints.

Ca(BH4)2] n clusters as hydrogen storage material: A DFT study

Calcium borohydride is widely studied as a hydrogen storage material. However, investigations on calcium borohydride from a cluster perspective are seldom found. The geometric structures and binding energies of [Ca(BH4)2] n (n = 1–4) clusters are determined using density function theory (DFT). For the most stable structures, vibration frequency, natural bond orbital (NBO) are calculated and discussed. The charge transfer from (BH4) to Ca was observed. Meanwhile, we also study the LUMO–HOMO gap (E g) and the B–H bond dissociation energies (BDEs). [Ca(BH4)2]3 owns higher E g, revealing that trimer is more stable than the other forms. Structures don’t change during optimization after hydrogen radical removal, showing that calcium borohydride could possibly be used as a reversible hydrogen storage material. [Ca(BH4)2]4 has the smallest dissociation energy suggesting it releases hydrogen more easily than others.

Effect of the structural evolution on the ionic conductivity of Li-N-H system during the dehydrogenation

On the way to transform lithium amide (LiNH2) into lithium imide (Li2NH) by releasing H2, the 1:1 molar mixture of LiNH2-LiH forms cubic (Fm3¯m) non-stoichiometric complex hydride phases (Li1+xNH2−x; 0 < x < 1) that co-exist with the tetragonal (I4¯) LiNH2 and with the cubic (Fd3¯m) Li2NH, respectively, at the early and at the advanced stage of the dehydrogenation. The change in LiNH2 → Li2NH may be viewed as a mechanism which continuously fills up the vacant Li sites of the tetragonal structure and, in a parallel process, transforms the anions [NH2]− → [NH]2−. The Li-N-H system, thus formed, by releasing >6 wt. % H2 can offer high Li-ionic conductivity (>10−4 S·cm−1 at room temperature) having an electrochemical stability window >5 V. The study suggests that the Li-N-H system may be a prospective electrolyte in the all-solid-state Li-ion battery, in addition to its use as a reversible hydrogen storage material.

In Pursuit of Sustainable Hydrogen Storage with Boron-Nitride Fullerene as the Storage Medium.

Using well calibrated DFT studies we predict that experimentally synthesized B24 N24 fullerene can serve as a potential reversible chemical hydrogen storage material with hydrogen-gas storage capacity up to 5.13 wt %. Our theoretical studies show that hydrogenation and dehydrogenation of the fullerene framework can be achieved at reasonable rates using existing metal-free hydrogenating agents and base metal-containing dehydrogenation catalysts.

Pd@C3N4 nanocatalyst for highly efficient hydrogen storage system based on potassium bicarbonate/formate

Formate/bicarbonate system has several desirable properties such as noncorrosive and nonirritating nature, as well as facile handling, which make it an attractive candidate for a safe, reversible hydrogen storage material. Herein, Pd nanoparticles supported on mesoporous graphitic carbon nitride (mpg‐C3N4) for formate‐based reversible hydrogen storage is reported. The as‐developed Pd/mpg‐C3N4 material was shown to be a superior catalyst for the hydrogenation of high concentrations of bicarbonate to formate under mild conditions. The effects of reaction temperature, H2 pressure, and bicarbonate concentration on the hydrogenation of bicarbonate to formate were investigated. The catalytic performance remained steady with high activity up to six hydrogenation cycles. The interaction between mpg‐C3N4 and Pd nanoparticles and the concerted effects of the nitrogen species located at mpg‐C3N4 and bicarbonate played a synergetic role in the enhancement of the performance of the catalyst for hydrogenation. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2410–2418, 2016

A composite of complex and chemical hydrides yields the first Al-based amidoborane with improved hydrogen storage properties.

The first Al-based amidoborane Na[Al(NH2 BH3 )4 ] was obtained through a mechanochemical treatment of the NaAlH4 -4 AB (AB=NH3 BH3 ) composite releasing 4.5 wt % of pure hydrogen. The same amidoborane was also produced upon heating the composite at 70 °C. The crystal structure of Na[Al(NH2 BH3 )4 ], elucidated from synchrotron X-ray powder diffraction and confirmed by DFT calculations, contains the previously unknown tetrahedral ion [Al(NH2 BH3 )4 ](-) , with every NH2 BH3 (-) ligand coordinated to aluminum through nitrogen atoms. Combination of complex and chemical hydrides in the same compound was possible due to both the lower stability of the AlH bonds compared to the BH ones in borohydride, and due to the strong Lewis acidity of Al(3+) . According to the thermogravimetric analysis-differential scanning calorimetry-mass spectrometry (TGA-DSC-MS) studies, Na[Al(NH2 BH3 )4 ] releases in two steps 9 wt % of pure hydrogen. As a result of this decomposition, which was also supported by volumetric studies, the formation of NaBH4 and amorphous product(s) of the surmised composition AlN4 B3 H(0-3.6) were observed. Furthermore, volumetric experiments have also shown that the final residue can reversibly absorb about 27 % of the released hydrogen at 250 °C and p(H2 )=150 bar. Hydrogen re-absorption does not regenerate neither Na[Al(NH2 BH3 )4 ] nor starting materials, NaAlH4 and AB, but rather occurs within amorphous product(s). Detailed studies of the latter one(s) can open an avenue for a new family of reversible hydrogen storage materials. Finally, the NaAlH4 -4 AB composite might become a starting point towards a new series of aluminum-based tetraamidoboranes with improved hydrogen storage properties such as hydrogen storage density, hydrogen purity, and reversibility.

Dehydrogenation kinetics, reversibility, and reaction mechanisms of reversible hydrogen storage material based on nanoconfined MgH2−NaAlH4

Studies of dehydrogenation kinetics, reversibility, and reaction mechanisms during de/rehydrogenation of nanoconfined MgH2−NaAlH4 into carbon aerogel scaffold (CAS) for reversible hydrogen storage material are for the first time proposed. Two different MgH2:NaAlH4 molar ratios (1:1 and 2:1) of hydride composite are melt infiltrated into CAS under 1:1 (CAS:hydride composite) weight ratio. Successful nanoconfinement is confirmed by N2 adsorption−desorption. Multiple-step dehydrogenation of milled samples is reduced to two-step reaction due to nanoconfinement. Peak temperatures corresponding to main dehydrogenation of nanoconfined samples significantly reduce as compared with those of milled samples, i.e., ∆T=up to 50 and 34°C for nanoconfined sample with 1:1 and 2:1 (MgH2:NaAlH4) molar ratios, respectively. Hydrogen content released (the 1st cycle) and reproduced (the 2nd, 3rd, and 4th cycles) of nanoconfined samples enhance up to 80% and 68% with respect to theoretical hydrogen storage capacity, respectively, while those of milled samples are 71% and 38%, respectively. Remarkable hydrogen content reproduced after nanoconfinement is due to the fact that metallic Al obtained after dehydrogenation (T=300°C under vacuum) of nanoconfined samples prefer to react with MgH2 and produces Al12Mg17, favorable for reversibility of MgH2−NaAlH4 system, whereas that of milled samples stays in the form of unreacted Al under the same temperature and pressure condition.

NaBH4 in "Graphene Wrapper:" Significantly Enhanced Hydrogen Storage Capacity and Regenerability through Nanoencapsulation.

A new high-capacity reversible hydrogen-storage material synthesized by the encapsulation of NaBH4 nanoparticles in graphene is reported. This approach effectively prevents phase agglomeration or separation during successive H2 discharge/recharge processes and enables rapid H2 uptake and release in NaBH4 under mild conditions. The strategy advanced here paves a new way for application in energy generation and storage.

Ammonia borane confined by poly(methyl methacrylate)/multiwall carbon nanotube nanofiber composite, as a polymeric hydrogen storage material

In this work, poly(methyl methacrylate)/ammonia borane/multiwall carbon nanotube (PMMA/AB/MWCNT) nanofiber composites have been fabricated and the synergetic nanoconfinement effect of nanofiber and CNT components on dehydrogenation temperature and liberating unwanted byproducts of AB (NH3BH3) have been studied. The results of dehydrogenation of PMMA/AB and PMMA/AB/MWCNT samples show 112 and 85 °C exothermic reaction temperatures, which are dramatically lower than pure AB (120 °C). Furthermore, by capture and interaction of AB molecules in the MWCNT and PMMA nanofiber structures, the enthalpy of exothermic decomposition decreases from −21.00 to −1.83 kJ mol−1 H2, suggesting that this type of AB nanofiber composite can provide a convenient reversible hydrogen storage material. The utilization of MWCNT as carbon catalyst and confining of AB result in a decrease of ammonia borane weight loss from 60.00 to 2.88 wt% which in turn can vigorously decline the emission of byproduct impurities. The synthesis process of PMMA/AB/MWCNT nanofiber composites causes the crystal structure of AB particles changed to the amorphous structure which has been clearly confirmed by X-ray diffraction analyses. The strategy of combining nanofiber structure and MWCNT as carbon catalyst with AB particles can be presented as a practicable solution to reach lower operational temperature and to decline undesirable volatile products.

Hydrogen absorption and lithium ion conductivity in Li6NBr3

The reaction of lithium amide and imide with lithium halides to form new amide halide or imide halide phases has led to improved hydrogen desorption and absorption properties and, for the amides, lithium ion conductivities. Here we investigate the effect of bromide incorporation on the ionic conductivity and hydrogen absorption properties of lithium nitride. For the first time we show that it is possible for a lithium halide nitride, the cubic bromide nitride Li6NBr3, to take up hydrogen—a necessary condition for potential use as a reversible solid-state hydrogen storage material. Powder X-ray diffraction showed the formation of Li2Br(NH2) and LiBr, and Raman spectroscopy confirmed that only amide anions were present and that the hydrogen uptake reaction had gone to completion. The lithium ion conductivity of Li6NBr3 at the hydrogenation temperature was found to be less than that of Li3N, which may be a significant factor in the kinetics of the hydrogenation process.

"H₂ sponge": pressure as a means for reversible high-capacity hydrogen storage in nanoporous Ca-intercalated covalent organic frameworks.

We explore the potential and advantages of Ca-intercalated covalent organic framework-1 (CaCOF-1) as a 3-dimensional (3D) layered material for reversible hydrogen storage. Density functional theory calculations show that by varying the interlayer distance of CaCOF-1, a series of metastable structures can be achieved with the interlayer distance falling in the range of 4.3-4.8 Å. When four hydrogen molecules are adsorbed on each Ca, a high hydrogen uptake of 4.54 wt% can be produced, with the binding energy falling in the ideal range of 0.2-0.6 eV per H2. While H2 absorption is a spontaneous process under H2 rich conditions, tuning the interlayer distance by reasonable external pressure could compress CaCOF-1 to release all of the hydrogen molecules and restore the material to its original state for recyclable use. This provides a new method for gradual, controllable extraction of hydrogen molecules in covalent organic frameworks, satisfying the practical demand for reversible hydrogen storage at ambient temperatures.

BC(3) sheet functionalized with lithium-rich species emerging as a reversible hydrogen storage material.

The decoration of a BC3 monolayer with the polylithiated molecules CLi4 and OLi2 has been extensively investigated to study the hydrogen-storage efficiency of the materials by first principles electronic structure calculations. The binding energies of both lithiated species with the BC3 substrate are much higher than their respective cohesive energies, which confirms the stability of the doped systems. A significant positive charge on the Li atom in each of the dopants facilitates the adsorption of multiple H2 molecules under the influence of electrostatic and van der Waals interactions. We observe a high H2 -storage capacity of 11.88 and 8.70 wt % for the BC3 -CLi4 and BC3 -OLi2 systems, respectively, making them promising candidates as efficient energy-storage systems.

Metalized T graphene: A reversible hydrogen storage material at room temperature

Lithium (Li)-decorated graphene is a promising hydrogen storage medium due to its high capacity. However, homogeneous mono-layer coating graphene with lithium atoms is metastable and the lithium atoms would cluster on the surface, resulting in the poor reversibility. Using van der Waals-corrected density functional theory, we demonstrated that lithium atoms can be homogeneously dispersed on T graphene due to a nonuniform charge distribution in T graphene and strong hybridizations between the C-2p and Li-2p orbitals. Thus, Li atoms are not likely to form clusters, indicating a good reversible hydrogen storage. Both the polarization mechanism and the orbital hybridizations contribute to the adsorption of hydrogen molecules (storage capacity of 7.7 wt. %) with an optimal adsorption energy of 0.19 eV/H2. The adsorption/desorption of H2 at ambient temperature and pressure is also discussed. Our results can serve as a guide in the design of new hydrogen storage materials based on non-hexagonal graphenes.

Electrospun PMMA/AB nanofiber composites for hydrogen storage applications

AbstractIn this work, poly(methyl methacrylate) (PMMA)/ammonia borane (AB) nanofiber composites were fabricated and the synergetic nanoconfinement effect of nanofibers on dehydrogenation temperature and the removal of unwanted by-products of AB (NH3 BH3) were studied. The results of the dehydrogenation of PMMA/AB samples showed an exothermic reaction temperature of 112°C, which is significantly lower than that of pure AB (120°C). Furthermore, the interaction between AB molecules and PMMA nanofiber structures decreased the enthalpy of exothermic decomposition, from -21.00 to -10.66 kJ/mol H2, suggesting that this type of AB nanofiber composite can provide a convenient reversible hydrogen storage material. Based on the thermogravimetric analysis curves, the use of PMMA to support AB in composite structures resulted in a decrease in AB weight loss from 60.00 to 11.10 wt.% which, in turn, could vigorously reduce the emission of by-product impurities. Based on the obtained results, the strategy of supporting AB in nanofiber structures can be presented as a practical solution to maintain lower operational temperatures and to reduce undesirable volatile products in the dehydrogenation process of AB.