The interaction of O2 with a reduced rutile TiO2(110) surface was investigated using density functional theory calculations. New insights were obtained into the distribution of bridge-bonded oxygen vacancies, the adsorption geometry, formation energy, reaction barrier and diffusion pathway of O2 on the surface. The calculations confirmed that the bridge-bonded oxygen vacancies tended to form single point defects because of repulsion between neighboring bridge-bonded oxygen vacancies. Converged density functional theory results indicated that an O2 landing on a reduced r-TiO2(110) surface would adsorb molecularly at low temperatures in good agreement with experimental observations below 100K. At room temperature, oxygen adsorbed dissociatively, after climbing an energy barrier. The calculations further showed that oxygen in dissociative configuration forms an OO complex on the surface, sitting between in-plane oxygen and Ti atoms. These were intrinsic properties of reduced r-TiO2(110) and the effect of bulk Ti-interstitials was neglected. Finally, the calculations showed that two O2 molecules reacting with a bridge-bonded oxygen vacancy could form an ozone molecule at low temperatures.

Interaction of O2 with Reduced Rutile TiO2(110) Surface. Xu, H., Tong, S.Y.: Surface Science, 2013, 610, 33-41