Synchrotron-Radiation Photoemission Study of Growth and Stability of Au Clusters on Rutile TiO₂(110)-1×1

The growth and thermal stability of Au clusters on a partially-reduced rutile TiO₂(110)-1×1 surface were investigated by high-resolution photoelectron spectroscopy using synchrotron- radiation-light. The valence-band photoelectron spectroscopy results demonstrate that the Ti³⁺3d feature attenuates quickly with the initial deposition of Au clusters, implying that Au clusters nucleate at the oxygen vacancy sites. The Au4f core-level photoelectron spectroscopy results directly prove the existence of charge transfer from oxygen vacancies to Au clusters. The thermal stability of Au clusters on the partially-reduced and stoichiometric TiO₂(110) surfaces was also comparatively investigated by the annealing experiments. With the same film thickness, Au clusters are more thermally stable on the partially-reduced TiO₂(110) surface than on the stoichiometric TiO₂(110) surface. Meanwhile, large Au nanoparticles are more thermally stable than fine Au nanoparticles.