Tunable Bi-bridge S-scheme Bi2S3/BiOBr heterojunction with oxygen vacancy and SPR effect for efficient photocatalytic reduction of Cr(VI) and industrial electroplating wastewater treatment

Surface plasmon resonance (SPR), oxygen vacancy modification and the construction of S-scheme heterostructure are important strategies to enhance visible-light absorption and improve photocatalytic performance. Here, a Bi-bridge S-scheme Bi2S3/BiOBr heterojunction (Bi2S3/Bi/BiOBr) with oxygen vacancies and SPR effect of Bi metal was prepared by one-pot solvothermal method for Cr(VI) reduction. The 3:10 Bi2S3/Bi/BiOBr exhibited superior visible-light photocatalytic reduction performance with 95.82 % Cr(VI) removal efficiency. Additionally, the 3:10 Bi2S3/Bi/BiOBr showed high stability and good anti-interference ability, and can effectively remove Cr(VI) from industrial electroplating wastewater with 97 % of Cr(VI) removal efficiency and residual Cr(VI) concentration of 0.304 mg/L, meeting the industrial effluent standard, which made it potentially attractive for real wastewater treatment. The enhanced photocatalytic performance of Bi2S3/Bi/BiOBr heterojunction was attributed to Bi metal SPR effect and the role of Bi as e-bridge, the presence of oxygen vacancies, the formation of internal electric field and S-scheme charge transfer, which were confirmed by various experimental results and density functional theory (DFT) calculations. This work provided theoretical and experimental reference for the construction of stable S-scheme heterojunctions with high catalytic activity and anti-interference, and a reliable solution for Cr(VI) removal from electroplating wastewater.