Structure and stability of Au rods onTiO2(110)surfaces by first-principles calculations

Abstract

In order to examine atomic and electronic structures of the perimeter of Au-particle/${\text{TiO}}_{2}$ systems related to the catalytic activity, we perform density-functional theory calculations of Au-rod/${\text{TiO}}_{2}(110)$ models with the relationship of $\text{Au}(111)[0\char21{}11]\ensuremath{\parallel}{\text{TiO}}_{2}(110)[001]$ observed by electron microscope. We deal with models of different interface stoichiometry with various rigid-body translations. For the stoichiometric systems, stable configurations have Au-O bonds between edge-Au and bridging-O atoms at the perimeter. For the Ti-rich systems with bridging-O atoms removed under a Au rod, rather strong Au-Ti bonds with covalent nature are formed and appear at the perimeter as well as weak Au-O bonds. For the O-rich systems formed by digging a pit under a Au rod, quite strong Au-O bonds with significant $\text{Au}\text{ }5d\text{-O}\text{ }2p$ hybridization and charge transfer like gold-oxides are formed and appear at the perimeter as well as rather weak Au-O bonds. About the relative stability among the systems with different stoichiometry, ab initio atomistic thermodynamics has shown that the O-rich $\text{Au}/{\text{TiO}}_{2}$ systems can be the most stable in usual atmosphere of the catalyst formation, indicating the importance of the perimeter of O-rich interfaces.