CO oxidation on inverse Fe2O3/Au(1 1 1) model catalysts

CO oxidation is studied at pressures between 4 and 100 Torr and temperatures from 400 K to 670 K on inverse model catalysts made of Fe2O3 nanoclusters grown on a Au(1 1 1) single crystal surface. The addition of Fe2O3 nanoclusters transformed the inert Au(1 1 1) single crystal into an active catalyst for CO oxidation. The catalytic activity increases with iron oxide coverage initially and then decreases when the iron oxide coverage is greater than 0.5 monolayers. Additionally, when the iron oxide particles form a continuous film on Au(1 1 1), there is no catalytic activity. These experimental results strongly suggest that the active sites for CO oxidation are located at the iron oxide/gold perimeter. Kinetic measurements suggest that CO oxidation by chemisorbed oxygen at the Fe2O3/Au perimeter is likely to be the rate-limiting step. Carbon deposition observed via a post-reaction Auger electron spectra suggests that multiple reaction pathways are involved in CO oxidation over Fe2O3/Au(1 1 1).