Manipulating Atomic Structures at the Au/TiO₂ Interface for O₂ Activation

The metal/oxide interface has been extensively studied due to its importance for heterogeneous catalysis. However, the exact role of interfacial atomic structures in governing catalytic processes still remains elusive. Herein, we demonstrate how the manipulation of atomic structures at the Au/TiO₂ interface significantly alters the interfacial electron distribution and prompts O₂ activation. It is discovered that at the defect-free Au/TiO₂ interface electrons transfer from Ti³⁺ species into Au nanoparticles (NPs) and further migrate into adsorbed perimeter O₂ molecules (i.e., in the form of Au-O-O-Ti), facilitating O₂ activation and leading to a ca. 34 times higher CO oxidation activity than that on the oxygen vacancy (V_o)-rich Au/TiO₂ interface, at which electrons from Ti³⁺ species are trapped by interfacial V_o on TiO₂ and hardly interact with perimeter O₂ molecules. We further reveal that the calcination releases those trapped electrons from interfacial V_o to facilitate O₂ activation. Collectively, our results establish an atomic-level description of the underlying mechanism regulating metal/oxide interfaces for the optimization of heterogeneous catalysis.