Constructing the dual active site at the Bi₂WO₆/BiOCl interface by coupling oxygen defects with the Z-scheme heterojunction interface for synergistic removal of CIP and Cr (VI)

The insufficient concentration of active sites in photocatalysts poses a challenge for environmental pollution control in photocatalytic technology. Based on this, a nanoflowers Bi₂WO₆/BiOCl heterojunction has been successfully designed. The unique flower-like structure enhances the absorption range of visible light. The large amount of H⁺ generated by NH₄⁺ assisting CH₃COOH could facilitate the breaking of Bi-O bonds in Bi₂WO₆/BiOCl, leading to the formation of oxygen defects. The carrier migration pathway of the Z-scheme maintains a strong redox potential and inhibits the recombination of electrons and holes. The interface coupling effect between oxygen defects and Z-scheme heterojunctions leads to the formation of dual active centers at the interface, significantly increasing the concentration of active sites. The photocatalytic activity of BWO/BOC is verified through the removal of CIP and Cr(VI). The catalytic rate constants of Cr(VI)(K = 0.07605 min⁻¹) and CIP(K = 0.06622 min⁻¹) in the composite system are significantly higher than those for the removal of single Cr(VI)(K = 0.0545 min⁻¹) and single CIP(K = 0.05662 min⁻¹). This result demonstrates that the catalytic synergy between CIP and Cr(VI) in the composite system enhances their catalytic efficiency and reduces the removal time of CIP and Cr(VI). This study designed a dual-active-site strategy for photocatalysts, offering a fresh perspective for addressing pollutant management in composite systems.