Water‐Tolerant Lead Halide Perovskite Nanocrystals as Efficient Photocatalysts for Visible‐Light‐Driven CO 2 Reduction in Pure Water

Lead halide perovskite (LHP) nanocrystals have recently been actively investigated for photocatalysis, owing to their inexpensive fabrication and excellent optoelectronic properties. However, LHP nanocrystals have not been used for artificial photosynthesis in aqueous solution, owing to their high sensitivity to water. In this study, water‐tolerant cobalt‐doped CsPbBr 3 /Cs 4 PbBr 6 nanocrystals have been prepared with the protection of hexafluorobutyl methacrylate. The resultant materials are employed as efficient photocatalysts for visible‐light‐driven CO 2 reduction in pure water. The perovskite nanocrystals with 2 % cobalt doping afford an impressive overall yield of 247 μmol g −1 for photocatalytic CO 2 conversion into CO and CH 4 , using water as an electron source. This study represents a significant step for practical artificial photosynthesis by using LHP nanocrystals as photocatalysts in aqueous solution.