Surface\nHalogen Compensation on CsPbBr₃ Nanocrystals with SOBr₂ for Photocatalytic CO₂ Reduction

Abstract

Metal halide perovskite nanocrystals (MHP NCs) have attracted\ngreat\ninterest for photocatalytic CO₂ reduction. However, monodispersed\nMHP NCs generally possess a halogen-deficient surface and are capped\nby labile long-chain organic ligands, exhibiting low charge transfer\nrates to nearby cocatalysts in photocatalytic systems. Conventional\nmethods of removing the surface ligands easily bring new surface defects,\nleading to serious charge recombination and low photocatalytic performance.\nHerein, we demonstrate a facile halogen compensation method to obtain\nhigh-quality CsPbBr₃ NCs with a Br-filled surface toward\nphotocatalytic CO₂ reduction. The use of reactive thionyl\nbromide (SOBr₂) not only promotes the stripping of native\nligands but also repairs Br vacancies (V_Br) on CsPbBr₃ NCs. Such a halogen compensation method facilitates the charge\ntransfer from CsPbBr₃ NCs to nearby cocatalysts (e.g.,\ng-C₃N₄), resulting in a high CO/CH₄ production rate of 190 μmol g^–1 h^–1 in photocatalytic CO₂ reduction. This work provides a\nnew strategy to simultaneously enhance the surface properties of photocatalysts\nand build a favorable interface for their charge transfer, showing\ngreat potential in the design and application of perovskites NCs for\nphotocatalytic applications.