Identification of the Catalytic Site at the Interface Perimeter of Au Clusters on Rutile TiO2(110)

We present a density functional theory study of the CO oxidation reaction at a Au-24 cluster supported on a rutile TiO2(110) slab. The global minimum structure of the Au-24 cluster is found using a genetic algorithm search. Catalytic sites are found at the perimeter of the Au-TiO2 interface but with strong dependence on the surface direction. It is shown how the CO oxidation reaction only happens along the [1 (1) over bar0] direction of the support and not along the [001] direction. This effect is attributed to a too weak CO binding energy along the [001] direction caused by the charge state and Au-Au coordination of the Au atoms along this direction.