In-Depth Understanding of the Effect of Halogen-Induced Stable 2D Bismuth-Based Perovskites for Photocatalytic Hydrogen Evolution Activity

Halide perovskites are excellent catalysts for photocatalytic hydrogen (H-2) evolution; however, their instability in aqueous systems limits their applications. In this study, an alternative system is presented to avoid the ionization of halide perovskites based on ethanol splitting and three Bi-based halide perovskite nanosheets (Cs3Bi2X9 PNs; X = I, Br, Cl) are prepared for H-2 evolution. Small amounts of these halide perovskites possess good stability in ethanol, where the optimal Cs3Bi2I9 PNs exhibit the highest H-2 evolution rate of 2157.8 mu mol h(-1) g(-1). In particular, the effects of halogen regulation on the H-2 evolution activity are investigated in depth from various perspectives for Cs3Bi2X9. The increased number of halogen atoms reduces the Bi center dot center dot center dot Bi distance in the octahedral configuration and eliminates the strong localization of electron-hole pairs, which are conducive to photogenerated charge separation and transfer. In addition, the dominant contribution of halogens to the conduction band is enhanced with an increase in the halogen atomic number. This study establishes a novel strategy for studying Bi-based perovskites for optimizing their photocatalytic properties. Furthermore, it provides a new perspective for developing highly efficient and stable H-2 evolution systems for halide perovskites.

Automated summary

In this study, three Bi-based halide perovskite nanosheets were prepared through ethanol splitting, and they exhibited good stability in ethanol. It was found that increasing the number of halogen atoms can enhance the H-2 evolution activity of the perovskites.