Surface-iodination-induced efficient charge separation in bismuth oxysulfide crystals for enhanced photocatalytic CO2 conversion

Abstract

Solar-energy-driven CO2 conversion to green fuels has great potential to alleviate energy crises and environmental issues. However, the low separation efficiency of charge carriers and the weak adsorption ability towards CO2 still hamper the efficiency of photocatalytic CO2 reduction. Herein, surface iodinated Bi2O2S materials (IBOS) were demonstrated to be efficient [Bi2O2]2+-containing photocatalysts, which could be prepared through facile hydrothermal process. The surface iodide ions are grafted onto the Bi atoms of Bi2O2S by replacing surface adsorbed OH, which slightly changes the electronic structure and then facilitates the separation of photo-generated electrons and holes in IBOS. Meanwhile, surface iodination also exhibits an enhanced adsorption and activation ability towards CO2, which contributes to photocatalytic CO2 conversion to CH4. The vital role of surface iodination was evidenced by the experimental analyses and theoretical calculations in detail. The optimized 2.0%IBOS shows marked photocatalytic CO2 reduction performance with a CH4 yield of 80.03 μmol g−1 under 90 min of visible light irradiation, which is ∼25-folds higher than pristine Bi2O2S. The mechanism of green transformation of CO2 to CH4 on 2.0%IBOS was finally proposed by the analyses of in situ FT-IR patterns. This work offers inspiration in designing and modifying [Bi2O2]2+-containing photocatalysts for highly efficient photocatalytic CO2 conversion.