Passivating Defects and Constructing Catalytic Sites on CsPbBr 3 with ZnBr 2 for Photocatalytic CO 2 Reduction.

In recent years, halide perovskites have attracted considerable attention for photocatalytic CO ₂ reduction. However, the presence of surface defects and the lack of specific catalytic sites for CO ₂ reduction lead to low photocatalytic performance. In this study, we demonstrate a facile method that post-treats CsPbBr ₃ with ZnBr ₂ for photocatalytic CO ₂ reduction. Our experimental and characterization results show that ZnBr ₂ has a dual role: the Br ^- ions in ZnBr ₂ passivate Br vacancies (V _Br ) on the CsPbBr ₃ surface, while Zn ²⁺ cations act as catalytic sites for CO ₂ reduction. The ZnBr ₂ -CsPbBr ₃ achieves a photocatalytic CO evolution rate of 57 μmol g ^-1 h ^-1 , which is nearly three times higher than that of the pristine CsPbBr ₃ . The enhanced performance over ZnBr ₂ -CsPbBr ₃ is mainly due to the decreased V _Br and lower reaction energy barrier for CO ₂ 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.