Lead-Free Halide Perovskite Cs3 Bi2 x Sb2-2 x I9 (x ≈ 0.3) Possessing the Photocatalytic Activity for Hydrogen Evolution Comparable to that of (CH3 NH3 )PbI3.

Lead-free perovskites Cs3 Bi2 x Sb2-2 x I9 (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 (CH3 NH3 )PbI3 , Cs3 Bi2 x Sb2-2 x I9 has a better catalytic performance under air mass 1.5 G (AM 1.5 G) simulated sunlight (100 mW cm-2 ), powders of Cs3 Bi0.6 Sb1.4 I9 (100 mg) loaded with Pt nanoparticles show < H2 evolution rate of 92.6 µmol h-1 , which greatly exceeds that of (CH3 NH3 )PbI3 powders loaded with Pt nanoparticles (100 mg catalyst, 4 µmol h-1 ). The Cs3 Bi2 x Sb2-2 x I9 has a high stability, with no apparent decrease in catalytic activity after five consecutive H2 evolution experiments. The doping of Sb in Cs3 Bi2 x Sb2-2 x I9 effectively reduces the contribution of Bi3+ on the conduction band, attenuating the effect of Bi vacancy on band structure. Compared with pure Cs3 Bi2 I9 and Cs3 Sb2 I9 , Cs3 Bi2 x Sb2-2 x I9 has fewer midgap states and better optical absorption, which greatly enhances its performance for the hydrogen evolution reaction.