Density functional theory study on the metal-support interaction between a Au₉ cluster and an anatase TiO₂(001)...

Noble metals supported on TiO₂ surfaces have shown extraordinary photocatalytic properties in many important processes such as hydrogenation, water splitting, degradation of hazards, and so on. Using density functional theory calculations, this work has systematically investigated the microstructure and electronic structure of three different Au₉ isomers loaded on anatase TiO₂(001) surface. The calculated results show that the interaction between the Au₉ cluster and the TiO₂ support is closely related to the adsorption site and the stability of the Au₉ cluster in the gas phase. The adsorption energy of the 2D configuration is larger than that of the 3D configuration of the Au₉ cluster, owing to the stronger interactions between more adsorption sites. The stable adsorption site for Au₉ clusters deposited on the anatase TiO₂(001) surface tends to be the O_2c-O_2c hollow site. The presentation of the MIGS of the Au₉ cluster, the disappearance of surface states of the TiO₂(001) surface, and the shifting of the Fermi level from the top of the valence band to the bottom of the conduction band suggest strong interactions between the Au₉ clusters and the TiO₂(001) surface. Importantly, the electron transfer from the Au₉ clusters to the TiO₂ support occurs mainly through Au-O_2c interactions, which are mainly localized at the contact layer of the Au₉ clusters. These conclusions are useful to understand various physical and chemical properties of noble metal clusters loaded onto an oxide surface, and helpful to design novel metal/semiconductor functional composite materials and devices.