Passivating Defects and Constructing Catalytic Sites on CsPbBr3 with ZnBr2 for Photocatalytic CO2 Reduction

In recent years, halide perovskites have attracted considerable attention for photocatalytic CO2 reduction. However, the presence of surface defects and the lack of specific catalytic sites for CO2 reduction lead to low photocatalytic performance. In this study, we demonstrate a facile method that post-treats CsPbBr3 with ZnBr2 for photocatalytic CO2 reduction. Our experimental and characterization results show that ZnBr2 has a dual role: the Br– ions in ZnBr2 passivate Br vacancies (VBr) on the CsPbBr3 surface, while Zn2+ cations act as catalytic sites for CO2 reduction. The ZnBr2–CsPbBr3 achieves a photocatalytic CO evolution rate of 57 μmol g–1 h–1, which is nearly three times higher than that of the pristine CsPbBr3. The enhanced performance over ZnBr2–CsPbBr3 is mainly due to the decreased VBr and lower reaction energy barrier for CO2 reduction. This work presents an effective method to simultaneously passivate surface defects and introduce catalytic sites, providing useful guidance for the regulation of perovskite photoelectric properties and the design of efficient photocatalysts.