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 Cs 2 Pt 0.25 Sn 0.75 Br 6 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 Cs 2 SnBr 6 perovskites. This doping approach allows Cs 2 Pt 0.25 Sn 0.75 Br 6 to work in the aqueous phase without saturated hydrohalic acid. The resultant dye-sensitized Cs 2 Pt 0.25 Sn 0.75 Br 6 perovskites exhibit a remarkable H 2 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 Cs 2 Pt 0.25 Sn 0.75 Br 6 . Furthermore, the more negative formation energy and decreased surface hydrophilicity endow Cs 2 Pt x Sn 1– x Br 6 with a high stability against water. This work represents a significant stride toward the realization of water-stable lead-free perovskites for photocatalysis.