The mechanism of photodriven oxidation of CO over anatase and rutile TiO2 investigated from the hydrogen adsorption behavior

Abstract In this study, the reaction mechanisms of photodriven CO oxidation over both anatase and rutile TiO2 have been investigated from the hydrogen adsorption behavior. It can be beneficial when H2 is introduced into CO oxidation system to increase the catalytic activity of rutile, while to decrease the catalytic activity of anatase. Further analysis revealed that H2 molecule is dissociated on anatase surface, and then produce oxygen vacancies by dehydroxylation under UV irradiation. In contrast, the adsorbed H2 (H2 (ads)) with a non-dissociative mode does not activate the lattice oxygen (Olat) over rutile. For anatase, CO oxidation reaction mainly undergoes the Olat activation process, while H2 (ads) can inhibit the Olat activation, resulting in a suppressed CO oxidation. For rutile, the surface hydroxyls are the active species for CO oxidation, while H2 (ads) can promote to form more surface hydroxyl species, resulting in a promoted CO oxidation.