Using ab initio quantum mechanical methods (DFT-GGA/LDA, pseudopotentials) we have investigated the adsorption properties of Au atoms on stoichiometric and reduced TiO2(110) rutile surfaces. This study predicts that the most stable adsorption site for the Au atom on the stoichiometric surface is on the fourfold hollow position over the fivefold-coordinated Ti and in-plane and bridging O atoms, indicated as the H2 site. At the H2 site, it is likely that the covalent and ionic bonding interactions with the fivefold-coordinated Ti and the bridging O, respectively, contribute synergistically to the Au adsorption. For Au adsorption over a neutral Fs0 center on the reduced surface, there is rather strong ionic bonding between the Au and surrounding sixfold-coordinated Ti atoms. The Au adsorption energy at the defect site is affected significantly by the presence of oxygen vacancies nearby along the  direction. Our DFT-GGA results clearly show that the binding of Au to an oxygen vacancy site is substantially stronger than to the stoichiometric surface.
Bibliographical noteFunding Information:
The authors acknowledge the Welch Foundation (grant no. F-1535) for their financial support of this work.
- Atom-solid interactions
- Density functional calculations
- Low index single crystal surfaces
- Surface defects
- Surface structure, morphology, roughness, and topography
- Titanium oxide