Lead-Free Halide Perovskite Cs Bi Sb I (x ≈ 0.3) Possessing the Photocatalytic Activity for Hydrogen Evolution Comparable to that of (CH NH )PbI.

Lead-free perovskites Cs Bi Sb I (x = 0.1, 0.3, 0.5, 0.7, 0.9) are prepared by a co-precipitation method and their photocatalytic performance for hydrogen production is studied in aqueous HI solution. Compared with the lead-based perovskite (CH NH )PbI , Cs Bi Sb I has a better catalytic performance under air mass 1.5 G (AM 1.5 G) simulated sunlight (100 mW cm ), powders of Cs Bi Sb I (100 mg) loaded with Pt nanoparticles show < H evolution rate of 92.6 µmol h , which greatly exceeds that of (CH NH )PbI powders loaded with Pt nanoparticles (100 mg catalyst, 4 µmol h ). The Cs Bi Sb I has a high stability, with no apparent decrease in catalytic activity after five consecutive H evolution experiments. The doping of Sb in Cs Bi Sb I effectively reduces the contribution of Bi on the conduction band, attenuating the effect of Bi vacancy on band structure. Compared with pure Cs Bi I and Cs Sb I , Cs Bi Sb I has fewer midgap states and better optical absorption, which greatly enhances its performance for the hydrogen evolution reaction.