Crystal-plane-dependent metal-support interaction in Au/TiO2.

Metal-support interactions between Au and TiO2 are studied based on Au/TiO2 catalysts with different TiO2 crystal planes exposed. With ex situ XPS, TEM and in situ DRIFTS, we have investigated the crystal-plane-dependent metal-support interaction effects on the physiochemical properties of Au/TiO2 catalysts. Based on the structural characterization and spectroscopic results, we can observe chemical oscillations (including the electronic structures of Au nanoparticles and the interaction between Au/TiO2 catalysts and CO molecules) during alternate H2 and O2 pre-treatments. Their variation tendencies of oscillations are greatly dependent on the crystal planes of TiO2 and the pre-treatment temperature. Furthermore, their surface and electronic changes after H2 and O2 pre-treatments can be well correlated with their catalytic activities in CO oxidation. Electron-transfer processes across the Au-TiO2 interface are proved to be the origin accounting for their changes after H2 and O2 pre-treatments. The different electronic structures of different TiO2 crystal planes should have relationships with the crystal-plane-dependent metal-support interaction effects in Au/TiO2.