Rich oxygen vacancies mediated bismuth oxysulfide crystals towards photocatalytic CO2-to-CH4 conversion

Oxygen vacancy-rich bismuth oxysulfide (Bi2O2S) with layered structure was prepared for efficient photocatalytic CO2 reduction under visible light irradiation. The existence of rich oxygen vacancies in Bi2O2S, which was proven by sufficient characterization, can provide abundant active sites, improve CO2 adsorption and activation abilities and boost the separation efficiency of photogenerated carriers, as determined by theoretical and experimental analyses. As a result, Bi2O2S with rich oxygen vacancies achieves excellent CO2 conversion with a CH4 production of 65.8 µmol g−1 under 90 min of visible light irradiation, which was 27-fold higher than the pristine Bi2O2S. The mechanism of photocatalytic conversion of CO2 to CH4 was also determined by in situ FT-IR analyses. This study provides an in-depth understanding of the development of Bi-O-S system photocatalysts through defect engineering for photocatalytic CO2 reduction.