Hydrogen adsorption and dissociation on nickel-adsorbed and -substituted Mg17Al12 (100) surface: A density functional theory study

Adsorption and dissociation properties of hydrogen on Ni-adsorbed and -substituted Mg17Al12 (100) surface are investigated systematically by means of the density functional theory calculations. Results show that one Ni atom prefers to adsorb on MgMg bridge site of the surface with adsorption energy −4.90 eV. For substitution systems, the Mg17Al12 (100) surface doped with 3.94 wt% and 7.69 wt% of Ni are considered. It is obtained that Ni atoms tend to replace Mg atoms occupied at the subsurfaces. With the addition of Ni, the energy of atomic (molecular) hydrogen adsorption (dissociation) on the Mg17Al12 (100) surface are significantly improved. The dissociation of H2 on the Ni-adsorbed surface is spontaneous. The mechanisms analyses based on the density functional theory are in line with the experimental results.