Introduction of economically viable hydrogen cars is hindered by the need to store large amounts hydrogen. Metal borohydrides [LiBH(4), Mg(BH(4))(2), Ca(BH(4))(2)] are attractive candidates for onboard storage because they contain high densities weight and volume. Using a set recently developed theoretical first-principles methods, we predict currently unknown crystal structures reactions in Li-Mg-Ca-B-H system. Hydrogen release from LiBH(4) Mg(BH(4))(2) predicted proceed via intermediate...

$\mathrm{Mg}({\mathrm{BH}}_{4}{)}_{2}$ contains a large amount of hydrogen by weight and volume, but its promise as candidate for storage is dependent on the currently unknown thermodynamics ${\mathrm{H}}_{2}$ release. Using first-principles density-functional theory calculations newly developed prototype electrostatic ground state search strategy, we predict new $T=0\text{ }\text{ }\mathrm{K}$ with $I\overline{4}m2$ symmetry, which $5\text{ }\mathrm{kJ}/\mathrm{mol}$ lower in energy than...

We demonstrate that NaAlH(4) confined within the nanopores of a titanium-functionalized metal-organic framework (MOF) template MOF-74(Mg) can reversibly store hydrogen with minimal loss capacity. Hydride-infiltrated samples were synthesized by melt infiltration, achieving loadings up to 21 wt %. possesses one-dimensional, 12 Å channels lined Mg atoms having open coordination sites, which serve as sites for Ti catalyst stabilization. is stable under repeated desorption and hydride...

The effects of nanoconfinement on the structural phase transition, H2 release and uptake, emission toxic diborane (B2H6) desorption LiBH4 have been comprehensively investigated in presence various porous hard carbon templates at a variety pore sizes. Calorimetry signatures both transition melting nanoconfined shifted to lower temperature with respect bulk, finally vanishing below size around 4 nm. confined these nanoporous carbons shows systematic monotonic decrease concomitantly, mass...

The wetting and decomposition behavior of LiBH4 has been investigated in the presence highly ordered nanoporous hard carbon (NPC) with hexagonally packed 2 nm diameter columnar pores. Calorimetry, X-ray diffraction, IR spectroscopy measurements confirm that within pores is amorphous. confinement such small results disappearance low-temperature structural phase transition, melting also significant decrease onset desorption temperature from 460 to 220 °C respect bulk LiBH4, a lower than...

A lithium salt of anionic scandium tetraborohydride complex, LiSc(BH4)4, was studied both experimentally and theoretically as a potential hydrogen storage medium. Ball milling mixtures LiBH4 ScCl3 produced LiCl unique crystalline hydride, which has been unequivocally identified via multinuclear solid-state nuclear magnetic resonance (NMR) to be LiSc(BH4)4. Under the present reaction conditions, there no evidence for formation binary Sc(BH4)3. These observations are in agreement with our...

Confining NaAlH4 in nanoporous carbon scaffolds is known to alter the sorption kinetics and/or pathways of characteristic bulk hydride reactions through interaction with framework at interface, increased specific surface area resulting nanoparticles, decreased hydrogen diffusion distances, and prevention phase segregation. Although nanosize effects have been well studied, influence scaffold chemistry remains unclear. Here we compare characteristics confined by melt infiltration...

Polarized Raman scattering on single crystals of has been used to determine the symmetry properties and frequencies Raman-active vibrational modes over temperature range from 300 425 K, i.e., up melting point . Significant softening (by 6%) is observed in involving rigid translations cations librations Surprisingly, data indicate mode less than 1.5% for Al- stretching bending anion. These results show that anion remains a stable structural entity even near point. First-principles linear...

We have developed a procedure for crystal structure generation and prediction ionic compounds consisting of collection cations rigid complex anions. Our approach is based on global optimization an energy functional the electrostatic soft-sphere repulsive energies using Metropolis Monte Carlo (MMC) simulated annealing in conjunction with smoothing potential landscape via distance scaling method. The resulting structures, or prototype ground states (PEGS), are subsequently relaxed...

Calcium borohydride, containing almost 12 wt % of hydrogen, is one the most promising and actively studied materials for hydrogen storage. However, experimental diffraction spectra indicate more than crystal structure depending on synthesis technique temperature. Two structures, ground-state in symmetry Fddd, or F2dd elevated temperature polymorph P42/m, are presumed known. We identify three low energy candidates Ca(BH4)2 predicted by methods prototype electrostatic ground states (PEGS)...

We have studied the decomposition pathway and products of Mg-borohydride using density functional theory (DFT) calculations free energy (including vibrational contributions) in conjunction with a Monte Carlo-based crystal structure prediction method, prototype electrostatic ground state (PEGS) search method. find that recently proposed Mg(B3H8)2 intermediate (Chong et al. Chem. Commun.2011, 47, 1330) is energetically highly unfavorable respect to into MgB12H12 hence not thermodynamic...

Neutron vibrational spectroscopy and quasielastic neutron scattering (QENS) were used to probe the dynamical properties of BH4– anions in both bulk LiBH4 confined nanoporous carbons (NPCs) having ≤4-nm-diameter, hexagonally arranged, cylindrical pores. The torsional band is significantly broadened relative that LiBH4, reflecting a disruption crystal lattice thus broader distribution rotational potentials. QENS measurements orthorhombic indicate single component yielding an activation energy...

Particle size and particle–framework interactions have profound effects on the kinetics, reaction pathways, even thermodynamics of complex hydrides incorporated in frameworks possessing nanoscale features. Tuning these properties may hold key to utilization practical applications for hydrogen storage. Using carefully synthesized, highly-ordered, nanoporous carbons (NPCs), we previously shown quantitative differences kinetics pathways LiBH4 when into frameworks. In this paper, probe anion...

Reactive nanoparticles are of great interest for applications ranging from catalysis to energy storage. However, efforts relate cluster size thermodynamic stability and chemical reactivity hampered by broad pore distributions poorly characterized environments in many microporous templates. Metal hydrides an important example this problem. Theoretical calculations suggest that reducing their critical dimension the nanoscale can some cases considerably destabilize these materials there is...

Cation substitution of Bi3+ with Fe3+ in BiOCl leads to the formation ionically layered Bi0.7Fe0.3OCl nanosheets. The synthesis follows a hydrolysis route using bismuth(III) nitrate and iron(III) chloride, followed by postannealing at 500 °C. Room temperature electrical conductivity improves from 6.11 × 10-8 S/m for 6.80 10-7 Bi0.7Fe0.3OCl. Correspondingly, activation energy conduction reduces 862 meV pure 310 These data suggest improved charge mobility Density functional theory calculations...

Detailed studies of the absorption and storage hydrogen by icosahedral quasicrystalline Ti-Zr-Ni are presented. Two different methods, one at room temperature another requiring elevated temperatures, successfully introduce into alloys. Absorption is accompanied an expansion quasilattice, results correlating rate to concentration The rates suggest that a surface oxide layer acts as barrier this confirmed depth profiling made with scanning Auger spectroscopy. Desorption also indicate some...