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

摘要

Halide perovskites are excellent catalysts for photocatalytic hydrogen (H_2) evolution;however, their instability in aqueous systems limits their applications. Inthis study, an alternative system is presented to avoid the ionization of halideperovskites based on ethanol splitting and three Bi-based halide perovskitenanosheets (Cs_3Bi_2X_9 PNs; X = I, Br, Cl) are prepared for H_2 evolution. Smallamounts of these halide perovskites possess good stability in ethanol, where theoptimal Cs_3Bi_2I_9 PNs exhibit the highest H_2 evolution rate of 2157.8 μmol h~(?)1 g~(?)1.In particular, the effects of halogen regulation on the H_2 evolution activity areinvestigated in depth from various perspectives for Cs_3Bi_2X_9. The increasednumber of halogen atoms reduces the Bi···Bi distance in the octahedral configurationand eliminates the strong localization of electron–hole pairs, which areconducive to photogenerated charge separation and transfer. In addition, thedominant contribution of halogens to the conduction band is enhanced with anincrease in the halogen atomic number. This study establishes a novel strategyfor studying Bi-based perovskites for optimizing their photocatalytic properties.Furthermore, it provides a new perspective for developing highly efficient andstable H_2 evolution systems for halide perovskites.