Investigation of the electronic interaction between TiO₂(1 1 0) surfaces and Au clusters by PES and STM

The electronic interaction between TiO₂(110) surfaces and Au clusters has been investigated by photoelectron spectroscopy (PES) and scanning tunneling microscopy (STM) to elucidate the high catalytic activity of Au/TiO₂. With increasing Au amount, the shift of O 2p nonbonding peak towards the Fermi level and the decrease in the Ti 3d peak area were precisely observed in the valence band PES spectra of Au/TiO₂(110). These changes in the valence band structure are attributed to the electron transfer from the surface defects on TiO₂(110) into the Au clusters. At the low coverage region, the STM images consistently show that the Au clusters nucleate at the surface defects of TiO₂(110). Here, we discuss the electronic interaction between the Au clusters and the TiO₂ surface relating to the catalytic activity of Au clusters on surfaces.