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

Abstract

Artificial photosynthetic reduction of CO2 into valuable chemicals is one of the most promising approaches to solve the energy crisis and decreasing atmospheric CO2 emissions. However, the poor selectivity accompanied by the low activity of photocatalysts limits the development of photocatalytic CO2 reduction. Herein, inspired by the use of oxygen vacancy engineering to promote the adsorption and activation of CO2 molecules, we introduced oxygen vacancies in the representative barium titanate (BaTiO3) photocatalyst for photocatalytic CO2 reduction. We found that oxygen vacancies brought significant differences in the CO2 photoreduction activity and selectivity of BaTiO3. The intrinsic BaTiO3 showed a low photocatalytic activity with the dominant product of CO, whereas BaTiO3 with oxygen vacancies exhibited a tenfold improvement in photocatalytic activity, with a high selectivity of ~ 90% to CH4. We propose that the presence of oxygen vacancies promotes CO2 and H2O adsorption onto the BaTiO3 surface and also improves the separation and transfer of photogenerated carriers, thereby boosting the photocatalytic CO2 reduction to CH4. This work highlights the essential role of oxygen vacancies in tuning the selectivity of photocatalytic reduction of CO2 into valuable chemicals.