The role of V2O5 on the dehydrogenation and hydrogenation in magnesium hydride: An ab initio study
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Ab initio density functional theory calculations are performed to study the experimentally observed catalytic role of V2O5 in the recycling of hydrogen in magnesium hydride. We find that the Mg-H bond length becomes elongated when MgH2 clusters are positioned on single, two, and three coordinated oxygen sites (O-1, O-2, and O-3) on the V2O5(001) surface. Molecular hydrogen is predicted to spontaneously form at the hole site on the V2O5(001) surface. Additionally, the activation barrier for the dissociation of hydrogen on V-doped Mg(0001) surface is 0.20 eV, which is only 1/5 of that on pure Mg(0001) surface. Our results indicate that oxygen sites on the V2O5(001) surface and the V dopant in Mg may be important facilitators for dehydrogenation and rehydrogenation, respectively. The understanding gained here will aid in the rational design and development of Mg-based hydrogen storage materials. (c) 2008 American Institute of Physics.
Applied Physics Letters
Solid State Chemistry
Physical Chemistry of Materials