In Situ Construction of Lead‐Free Perovskite Direct Z‐Scheme Heterojunction Cs₃Bi₂I₉/Bi₂WO₆ for Efficient Photocatalysis of CO₂ Reduction

Abstract

The well‐known toxicity of lead‐halide‐perovskite (LHP) nanocrystals limits their commercial applications in photocatalysis. Herein, an in situ controlled growth strategy is reported for lead‐free perovskite nanocrystals (Cs 3 Bi 2 I 9 ) on the surface of ultrathin Bi 2 WO 6 nanosheets through co‐sharing Bi atoms, to generate a direct Z‐scheme heterojunction of Cs 3 Bi 2 I 9 /Bi 2 WO 6 . Co‐sharing of the Bi atom can enable intimate contact and strong electron coupling between Cs 3 Bi 2 I 9 and Bi 2 WO 6 , which can effectively promote the interfacial charge transfer between Cs 3 Bi 2 I 9 and Bi 2 WO 6 complying with a Z‐scheme pathway. The resulting efficient charge transfer and well‐preserved redox ability of Cs 3 Bi 2 I 9 /Bi 2 WO 6 heterojunction endow it with a significant improvement of photocatalytic activity for the conversion of CO 2 ‐to‐CO integrated with water oxidation, exhibiting a fourfold increase compared with pure Cs 3 Bi 2 I 9 nanocrystals. This study paves a new avenue for the construction of efficient Z‐scheme heterojunction based on lead‐free halide perovskite, which should stimulate further passion on the development of high performance of lead‐free halide perovskite materials for photocatalytic application.