PVP Passivated δ-CsPbI: Vacancy Induced Visible-Light Absorption and Efficient Photocatalysis.

The aqueous instability of halide perovskite seriously hinders its direct application in water as a potential photocatalyst. Here, we prepared a new type of polyvinylpyrrolidone (PVP) passivated δ-CsPbI (δ-CsPbI@PVP) microcrystal by a facile method. This material can be uniformly dispersed in water and stably maintain its crystal structure for a long time, breaking through the bottleneck of halide perovskite photocatalysis in water. Under visible light, δ-CsPbI@PVP can almost completely photodegrade organic dyes (including Rhodamine B, methylene blue, and crystal violet) in only 20 min. The efficient photocatalytic activity is attributed to the enhanced visible light absorption arising from PbI defects in δ-CsPbI@PVP and the intrinsic low photoluminescence quantum yield of δ-CsPbI, which induces efficient light absorption and photocatalytic activity. We highlight δ-CsPbI@PVP as an effective aqueous photocatalyst, and this study provides new insights into how to exploit the potential of halide perovskite in photocatalytic applications.