Strain effect on the adsorption, diffusion, and molecular dissociation of hydrogen on Mg (0001) surface

TitleStrain effect on the adsorption, diffusion, and molecular dissociation of hydrogen on Mg (0001) surface
Publication TypeJournal Article
Year of Publication2013
AuthorsLei HP, Wang CZ, Yao YX, Wang YG, Hupalo M, McDougall D, Tringides M, Ho KM
Journal TitleJournal of Chemical Physics
Date Published12
Type of ArticleArticle
ISBN Number0021-9606
Accession NumberWOS:000328729000032
Keywordsab-initio, elastic band method, H-2, MAGNESIUM, metal-surfaces, mg(0001) surface, minimum energy paths, SADDLE-POINTS, storage, thin-films

The adsorption, diffusion, and molecular dissociation of hydrogen on the biaxially strained Mg (0001) surface have been systematically investigated by the first principle calculations based on density functional theory. When the strain changes from the compressive to tensile state, the adsorption energy of H atom linearly increases while its diffusion barrier linearly decreases oppositely. The dissociation barrier of H-2 molecule linearly reduces in the tensile strain region. Through the chemical bonding analysis including the charge density difference, the projected density of states and the Mulliken population, the mechanism of the strain effect on the adsorption of H atom and the dissociation of H-2 molecule has been elucidated by an s-p charge transfer model. With the reduction of the orbital overlap between the surface Mg atoms upon the lattice expansion, the charge transfers from p to s states of Mg atoms, which enhances the hybridization of H s and Mg s orbitals. Therefore, the bonding interaction of H with Mg surface is strengthened and then the atomic diffusion and molecular dissociation barriers of hydrogen decrease accordingly. Our works will be helpful to understand and to estimate the influence of the lattice deformation on the performance of Mg-containing hydrogen storage materials. (C) 2013 AIP Publishing LLC.

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