Modulating the Selectivity of Photocatalytic CO2 Reduction in Barium Titanate by Introducing Oxygen Vacancies

Abstract Artificial photosynthetic reduction of CO 2 into valuable chemicals is one of the most promising approaches to solve the energy crisis and decreasing atmospheric CO 2 emissions. However, the poor selectivity accompanied by the low activity of photocatalysts limits the development of photocatalytic CO 2 reduction. Herein, inspired by the use of oxygen vacancy engineering to promote the adsorption and activation of CO 2 molecules, we introduced oxygen vacancies in the representative barium titanate (BaTiO 3 ) photocatalyst for photocatalytic CO 2 reduction. We found that oxygen vacancies brought significant differences in the CO 2 photoreduction activity and selectivity of BaTiO 3 . The intrinsic BaTiO 3 showed a low photocatalytic activity with the dominant product of CO, whereas BaTiO 3 with oxygen vacancies exhibited a tenfold improvement in photocatalytic activity, with a high selectivity of ~ 90% to CH 4 . We propose that the presence of oxygen vacancies promotes CO 2 and H 2 O adsorption onto the BaTiO 3 surface and also improves the separation and transfer of photogenerated carriers, thereby boosting the photocatalytic CO 2 reduction to CH 4 . This work highlights the essential role of oxygen vacancies in tuning the selectivity of photocatalytic reduction of CO 2 into valuable chemicals.