(700e) Stm Studies of the Structure of Catalytically Active Gold

Previously, we have reported the synthesis of well-ordered Au mono- and bi-layer films on a TiOx/Mo(112). Kinetic measurements for the catalytic oxidation of carbon monoxide show that the Au bi-layer structure is significantly more active (by more than an order of magnitude) than the monolayer, and is about 45 times higher than that reported for the most active higher-surface-area Au/TiO2 catalyst. Here we report our recent STM studies of this system. The wetting of Au on the (8x2)-TiOx is clearly evidenced, and the ordered (1x1) mono- and (1x3) bi-layer structures are atomic resolved. The electronic and chemical properties of these ordered Au films have been characterized by IRAS using CO as a probe molecule and UPS. The common structural features of ordered Au bi-layers and Au bi-layer nanoparticles on TiO2(110) are described, and the exceptionally high catalytic activity of the Au bi-layer structure related to its unique electronic properties.