Unravelling the Origin of the High-Catalytic Activity of Supported Au:  A Density-Functional Theory-Based Interpretation

Using first principles DF calculations we have studied the structural and catalytic properties of Au supported on TiO_x−Mo(112) films. Our theoretical models are consistent with an initial (8 × 2) Mo(112)−Ti₂O₃ pattern which after Au deposition gives rise to ordered Au films that completely wet the surface. The oxidation of CO on model surfaces at coverage 1, ⁴/₃, and ⁵/₂ ML has been analyzed. The oxidation proceeds through a peroxo-like complex in which molecular oxygen is simultaneously bound to the CO and the surface. The energy barrier computed for a Au coverage of ⁴/₃ ML is found significantly lower in agreement with the unusual high activity observed for this catalyst. The detailed analysis of the geometry and electronic structure provides a fundamental understanding of the reaction.