ADSORPTION AND DIFFUSION OF HYDROGEN ON LOW-INDEX (110) AND (111) SURFACES OF ALUMINUM

By the density-functional method, the authors have considered the energetics of adsorption and diffusion of a hydrogen molecule into atomically thin aluminum plates with body-centered tetragonal and rhombohedral crystallite structures bounded by the (110) and (111) surfaces, and also geometric confi gurations of surface aluminum hydrides. It has been shown that physical adsorption of H2 molecules on the Al(110) and Al(111) surfaces is a weak exothermic process. Polarization and deformation due to the physical adsorption lead to a certain increase in the H–H interatomic spacing (0.734 Å). The diffusion of the hydrogen atoms into body-centered tetragonal and rhombohedral plates tends to increase the system's energy. It has been found that hydrogen diffuses most easily through the Al(110) surface; in atomic diffusion through the subsurface layer, the energy grows up to 1.1 eV. A stable energy state is attained due to the formation of a tetrahedral hydrogen complex.
   
Author:  A. L. Zaitsev and T. N. Genarov
Keywords:  adsorption of hydrogen, diffusion of hydrogen, aluminum hydride, low-index aluminum surface, ab initio solution
Page:  1603