Interplay between Methanol and Anatase TiO₂(101) Surface: The Effect of Subsurface Oxygen Vacancy

Abstract

The dissociation of methanol plays a vital role in many reactions of C1 chemistry. The effect of defects on methanol dissociation is unclear. The adsorption and reactivity of methanol on the anatase TiO2(101) surface with or without a subsurface oxygen vacancy (VOsub) have been studied using first-principles calculations. The adsorbed methanol on the perfect surface prefers the molecular state with a dissociation energy barrier of 0.56 eV. Interestingly, the adsorption and reactivity of methanol are greatly promoted by VOsub. Upon methanol adsorption, the predominant VOsub on the clean surface becomes active, which is comparable to the surface oxygen vacancy (VOsur). The VOsub migrates from the subsurface to the surface layer with a low energy barrier of 0.17 eV, and then the adsorbed methanol molecule easily dissociates through a barrierless pathway facilitated by VOsur. Such results clearly reveal that the VOsub plays a vital role in the dissociation of methanol. These results may provide new insights into photocatalytic activity of organic molecules on anatase TiO2 nanoparticles.