Insight into the effect of oxygen vacancies and OH groups on anatase TiO2 for CO oxidation: A combined FT-IR and density functional theory study

Anatase TiO2 plays an important role in catalytic reaction. The present work focused on surface structural and electric structural properties of the anatase TiO2 doped with some 3d transition metals (Mn, Fe and Co). Taking the CO oxidation as a probe reaction, attempts to explain the influence of oxygen vacancies and surface OH groups on the reaction mechanism by using FT-IR characterization and DFT calculation. It is found that doping can activate the surface lattice oxygen by introducing spin polarization, thereby increasing the oxygen vacancy to adsorb more chemisorbed oxygen. It is also found that OH groups increase the catalytic performance by forming bicarbonate which is eventually consumed. At low temperature, the CO oxidation reaction by surface reactive oxygen species and hydroxyl groups together. At high temperature, CO molecules are oxidized by surface reactive oxygen species with CO2 desorption step as the controlling step. Finally, the reaction mechanism was summarized as a Eley-Rideal mechanism.