Ab initio density functional theory calculations were performed in order to study the diffusion of atomic H on a Mg(00▪1) surface and its migration into the sub-surface layers. A C atom located initially on a Mg(00▪1) surface could migrate into the sub-surface layer and occupy a face-centered cubic site, with charge transfer to the C atom from neighboring Mg atoms. The cluster of positively charged Mg atoms surrounding a sub-surface C was then shown to facilitate the dissociative chemisorption of molecular H on the Mg(00▪1) surface, and the surface migration and subsequent diffusion into the sub-surface of atomic H. This explained an experimentally observed improvement in the absorption kinetics of H2 which occurred when graphite or single-walled C nanotubes were introduced into the Mg powder during ball milling.

Atomic Hydrogen Diffusion in Novel Magnesium Nanostructures - the Impact of Incorporated Sub-Surface Carbon Atoms. A.J.Du, S.C.Smith, X.D.Yao, Y.He, G.Q.Lu: Journal of Physics - Conference Series, 2006, 29, 167-72