Synthesis of Stable Lead‐Free Cs ₃ Sb ₂ (Br _x I _{1− x} ) ₉ (0 ≤ x  ≤ 1) Perovskite Nanoplatelets and Their Application in CO ₂ Photocatalytic Reduction

Exploring photocatalysts to foster CO2 photoreduction into high value-added chemicals is of great significance. Lead halide perovskites (LHPs) have recently been extensively investigated as photocatalysts, owing to their facile fabrication and prominent optoelectronic properties. However, the toxicity of lead and instability will hinder their future large-scale applications. To address these challenges, a series of lead-free Sb-based all-inorganic mixed halide perovskite Cs3 Sb2 (Brx I1-x )9 (0 ≤ x ≤ 1) nanoplatelets (NPLs) is synthesized. The perovskite NPLs are prepared using a ligand-assisted re-precipitation approach at 50 °C. The authors observe the tunability of their optical band gaps from 2.1 to 2.5 eV, and they can maintain the excellent stability over 120 h under heating at 100 °C or UV light irradiation. The resultant materials are employed as efficient photocatalysts for visible-light driven CO2 reduction at the gas-solid interface. The Cs3 Sb2 (Br0.7 I0.3 )9 perovskite NPLs afford an impressive overall yield of 27.7 µmol g-1 for the selective photocatalytic conversion of CO2 into CO. This study represents a significant demonstration for practical artificial photosynthesis by using LHP materials as photocatalysts.