Design of double oxygen vacancy-rich Bi2O2S0.8F0.4/BiOBr S-scheme heterojunction via tuning band structure for CO2 photoreduction

S-scheme heterojunction has garnered significant interest owing to its distinctive band structure and interfacial interaction. In this work, nanosheets-like Bi₂O₂S_0.8F_0.4/BiOBr heterojunction photocatalyst with dual surface oxygen vacancies was synthesized by epitaxial growing method. The experiment results revealed that the evolution rate of CO from CO₂ photoreduction for optimal Bi₂O₂S_0.8F_0.4/BiOBr heterojunction was 219.3 μmol⸱g⁻¹⸱h⁻¹, being 9.8 times greater than that of pure BiOBr. The S-scheme band structure was shown to promote sunlight utilization, raise the reduction power of photogenerated electrons, and improve the separation and transfer of photogenerated charge carriers. Moreover, the presence of dual oxygen vacancies on the interfacial surface of Bi₂O₂S_0.8F_0.4/BiOBr heterojunction facilitates the adsorption and activation of CO₂ and H₂O molecules. The work focuses on the combined impact of the S-scheme band structure and oxygen vacancy on the property of photocatalytic reduction of CO₂. The study presents a straightforward strategy for the on-site creation of S-scheme heterojunction with defect.