Surface Defect Engineering of CsPbBr3 Nanocrystals for High Efficient Photocatalytic CO2 Reduction

Converting CO 2 into chemical fuels with sunlight is a very attractive approach to solve the greenhouse effect and fossil fuel crisis. Metal halide perovskite nanocrystals (NCs) have been identified as ideal semiconductor photocatalysts for photocatalytic CO 2 reduction due to their unique properties, such as strong light absorption, low exciton binding energy, tunable bandgaps, and low cost. However, the pristine perovskite NCs suffering from inevitable defects, which lower their charge transfer efficiency and are detrimental to photocatalytic performance toward CO 2 reduction. Herein, a facile approach to modify the surface defects of CsPbBr 3 NC is demonstrated using tetrafluoroborate salts as defects treatment agent and loading Co 2+ as a cocatalyst. As a result, the optimized Co 2+ on the surface of defect‐free CsPbBr 3 ‐BF 4 shows a remarkable photocatalytic CO 2 activity of 83.8 μmol g −1 h −1 , which indicates that the surface modification can effectively suppress the undesired charge recombination in CsPbBr 3 NC and promote its charge separation efficiency. This work provides an effective method to modify the surface defects of the CsPbBr 3 NCs for high efficient photocatalytic CO 2 reduction and broadens the photocatalytic applications of halide perovskites.