Effect of oxygen vacancy on the adsorption of O2 on anatase TiO2(001): A DFT-based study

Abstract

Abstract We performed density functional theory (DFT) based calculations to investigate the effects of O-vacancies on the adsorption of O 2 on anatase TiO 2 (001). Our calculation results show that we can promote O 2 adsorption on an initially inert stoichiometric TiO 2 (001) by introducing O-vacancy. The resulting excess electrons from the introduction of the O-vacancy redistribute around the neighboring Ti ions. An incoming O 2 can then adsorb at the O-vacancy site, either in the superoxide state (O 2 − ) or the peroxide state (O 2 2 − ). In the O 2 − state, the O O bond is oriented parallel to the surface, along [010]. In the O 2 2 − state, the O O bond is oriented perpendicular to the surface, along [001]. Healing of the surface occurs when one of the O atoms of the perpendicularly adsorbed O 2 fills the vacant site and the other atom diffuses, recovering the stoichiometric surface.