UCLA

With rising emission of CO 2 affecting human life, photocatalytic reduction of CO 2 attracts substantial research interest. Anatase TiO 2 is known to be one of the most promising catalysts of this process. Here, we adopted density functional theory calculations to systematically study the pathways of CO 2 reduction on the defected anatase TiO 2 (101) surface. We find that oxygen vacancies play a critical role in promoting the reaction, as compared to the pristine surface. They help CO 2 binding, activation, and dissociation and stabilize other reaction intermediates. The most feasible identified reaction mechanism proceeds through surface CO species, to CHO, CHOH, CH 2 OH or CHO, CH 2 O, and CH 3 O, to produce methane and methanol. In addition, there exists a carbene-like deoxygenation pathway to form the CH species on the vacancy, which can give rise to methane by binding protons successively.