Band Gap Tuning via Supercritical CO2-Induced Exciton Effect in BiFeO3 for Photocatalytic CO2 Reduction

The exciton effect induced by the Coulomb interaction between photogenerated electrons and holes has an important influence on physical processes such as light absorption, luminescence, excitation, and optical nonlinear interaction in semiconductors. However, there are few studies related to photocatalysis based on the exciton effect. For catalysts, dissociation and the coexistence of excitons are obstacles to the generation of carriers. Therefore, converting excitons to carriers will optimize the photocatalytic process. In this paper, we treated BiFeO3 with supercritical carbon dioxide (SC CO2) to strip two-dimensional (2D) BiFeO3 and introduced oxygen vacancies, which can dissociate excitons into carriers for photocatalytic reduction of CO2 under visible light. This work guides the development of the photocatalysis of BiFeO3 from a new view in terms of excitons.