Platinum Group Metal Adsorption on Clean and Hydroxylated Corundum Surfaces

The adsorption of Ni, Pd, and Pt on the clean and hydroxylated (0001) and (1 - 102) alpha-alumina has been investigated using first principles methods. On both clean surfaces, the metals have very similar adsorption mechanisms where the metal promotes a charge transfer from a surface oxygen to a surface aluminum. The adsorption mechanism on the hydroxylated surfaces is different due to the unavailability of surface aluminum. Strong stabilization of the metal by the hydroxyl groups is observed for Pt and Ni due to the rupture of a surface hydroxyl group and the formation of a hydride species on the metal. The stabilization of Pd is found to be much less marked than Pt and Ni due to the lower strength of the Pd-H bond.