Study of Interaction between Au and TiO<SUB>2</SUB>(110) at Low Coverage

Abstract

We have investigated the interaction between Au and a rutile TiO 2 (1 10) surface at low coverage, using density functional theory. We have examined Au adsorption on three types of TiO 2 (110) surface with different stoichiometry and structures; the stoichiometric surface, the surface formed by removing bridging-oxygen (defected surface), and the reconstructed 1 x 2 surface with Ti 2 O 3 rows (added-row surface). For the stoichiometric surface, the most stable site for the Au adsorption is the on-top site above the bridging-oxygen atom. Electrons transfer from the Au adatom to the bridging-oxygen atom after adsorption. For the defected surface, the most stable adsorption site is the bridging-oxygen vacant site. For the added-row surface, the most stable adsorption site is the neighborhood of the Ti 2 O 3 rows. For both the reduced surface, defected and added-row surfaces, electron densities between the Au and the reduced Ti atom increase after adsorption, and it seems that the Au atom covalently interacts with the reduced Ti atoms at the surface. Moreover, we compared the simulated scanning tunneling microscopy (STM) images with the experimental STM images for the added-row surface. The calculated STM images of Au adatom adsorbed near Ti 2 O 3 rows agree with experimental images qualitatively.