(628c) Heterogeneous Catalysis by Gold: Oxide-Specific O2 Interactions with Supported Gold

Oxide-supported Au nanostructures are promising low-temperature oxidation catalysts. It is generally observed that Au supported on reducible oxides is more active than the Au supported on irreducible oxides. Recent studies also suggest that cationic Auä+ is responsible for the unique Au/oxide catalytic activity. This observation is contrary to the conventional perception that oxide supports donate electronic charge to Au. We have utilized DFT calculations and ab initio thermodynamic studies to investigate the oxidation state of Au nanostructures deposited on reducible and irreducible supports. We find that there are fundamental differences in the electronic structure of Au deposited on the different oxides. We propose a simple model, grounded in the first principles calculations, which attempts to explain the oxide-specific catalytic activity of Au nanostructures and which can account for the presence and the role of cationic Auä+.