Origin of enhanced corrosion resistance of Ag and Au doped anatase TiO2

Abstract

Anatase TiO2 is a promising corrosion resistance material due to the excellent corrosion resistance, order array structure and good adsorption stability. However, the fundamental mechanism of interaction between TiO2 and sulfur (S) is unclear. In particular, the nature of corrosion resistance of alloy-doped TiO2 is not understood. By using the first-principles calculations, we study the sulfuretted mechanism of TiO2 and explore the influence of Ag and Au on the corrosion resistance of TiO2. The results show that sulfur is favorable to occupy the tetrahedral interstitial site because sulfur occupied this position can improve the localized hybridization between S-3p state and O-2p state, which forms the SO bond. The calculated bond length of SO bond is 1.967 Å. In particular, Ag dopant and Au dopant enhance the localized hybridization between sulfur and oxygen. The calculated bond length of SO bond for Ag dopant (1.483 Å) and Au dopant (1.506 Å) is shorter than that of S-doped TiO2. As a result, those alloying elements improve the corrosion resistance of TiO2. Compared to Au dopant, Ag dopant improves the corrosion resistance of TiO2 because the bond strength of SO bond for Ag dopant is stronger than that of Au dopant.