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.