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

[Display omitted] • Surface iodinated Bi 2 O 2 S were prepared as inspired [Bi 2 O 2 ]2+-containing materials. • Surface iodide ions facilitated the separation of photo-generated carriers in IBOS. • 2.0%IBOS exhibited superb abilities for the adsorption and activation toward CO 2. • The CH 4 yield of 80.03 μmol g−1 was achieved by visible light-driven CO 2 photoreduction. • The reaction mechanism was unveiled by experimental and theoretical analyses. Solar-energy-driven CO 2 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 CO 2 still hamper the efficiency of photocatalytic CO 2 reduction. Herein, surface iodinated Bi 2 O 2 S materials (IBOS) were demonstrated to be efficient [Bi 2 O 2 ]2+-containing photocatalysts, which could be prepared through facile hydrothermal process. The surface iodide ions are grafted onto the Bi atoms of Bi 2 O 2 S 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 CO 2 , which contributes to photocatalytic CO 2 conversion to CH 4. 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 CO 2 reduction performance with a CH 4 yield of 80.03 μmol g−1 under 90 min of visible light irradiation, which is ∼25-folds higher than pristine Bi 2 O 2 S. The mechanism of green transformation of CO 2 to CH 4 on 2.0%IBOS was finally proposed by the analyses of in situ FT-IR patterns. This work offers inspiration in designing and modifying [Bi 2 O 2 ]2+-containing photocatalysts for highly efficient photocatalytic CO 2 conversion. [ABSTRACT FROM AUTHOR]