In situ construction of S-scheme AgBr/BiOBr heterojunction with surface oxygen vacancy for boosting photocatalytic CO2 reduction with H2O

S-scheme heterojunction has attracted much attention due to its unique structure and interface interaction. Herein, AgBr/BiOBr heterojunction with surface oxygen vacancies (OVs) was in situ synthesized by a facile chemical method. It was found that the evolution rates of photoreduction of CO2 to CO and CH4 with 0.33AB are 212.6 and 5.7 μmol g−1 h−1 respectively, which are 9.2 and 5.2 times higher than those of pure BiOBr. It was demonstrated that the S-scheme band structure could improve the utilization of sunlight, increase the reduction power of photogenerated electrons, and enhance the separation and transfer of photogenerated charge carriers. Furthermore, the OVs on the surface of BiOBr for AgBr/BiOBr heterojunction are conductive to the adsorption and activation of CO2 molecules. The synergetic effect of S-scheme band structure and OVs on photocatalytic reduction of CO2 was discussed. The work provides a facile method for in situ construction of S-scheme heterojunction with defect for CO2 photoreduction.