Enabling Enhanced Photocatalytic Hydrogen Evolution in Water by Doping Cs2SnBr6 Perovskite with Pt

Lead (Pb) halide perovskites (LHPs) have attracted great interest in photocatalysis. However, the unsatisfactory stability and toxicity of Pb restrict its large-scale application. Herein, lead-free Cs2Pt0.25Sn0.75Br6 perovskites are reported for photocatalytic hydrogen reaction (HER) in water. The partial substitution of Sn atoms with Pt atoms dramatically enhances the HER performance and stability of the Cs2SnBr6 perovskites. This doping approach allows Cs2Pt0.25Sn0.75Br6 to work in the aqueous phase without saturated hydrohalic acid. The resultant dye-sensitized Cs2Pt0.25Sn0.75Br6 perovskites exhibit a remarkable H2 evolution rate of 11.49 mmol g–1 h–1 with an apparent quantum yield of 7.2%. Various investigations uncover that Pt doping significantly tunes the intrinsic properties and surface active sites of the Cs2Pt0.25Sn0.75Br6. Furthermore, the more negative formation energy and decreased surface hydrophilicity endow Cs2PtxSn1–xBr6 with a high stability against water. This work represents a significant stride toward the realization of water-stable lead-free perovskites for photocatalysis.