Adsorption of Pd atoms on g-Al2O3: a density functional study of metal–support interactions

The Pd/g-Al2O3 interface at low coverage has been theoretically studied by means of periodic-supercell density functional calculations. The most stable (1 1 0) g-Al2O3 clean surface plane has been modelled by using a six layers slab stoichiometric model of 40 atoms. A single Pd atom has been deposited on top of the surface in different positions, first freezing the surface structure and later allowing the surface to relax. The results indicate that the metal–support interaction is dominated by the strong Lewis acid properties of the tetrahedral cationic sites. It is also shown that in the octahedral cationic sites, adsorption of single Pd atoms induces a significant relaxation of the substrate. While the interaction energy with the preferred site is strong ( 3.8 eV), small differences are found for nearby sites, indicating a high mobility of Pd atoms on the surface, at least on the channels