Construction of a Double Z-Scheme CuO/Cu2O/CuS/ZnO Quaternary Heterojunction Photocatalyst with Enhanced Solar-Driven Photocatalytic Performance for Sulfamethoxazole Degradation

A novel CuO/Cu2O/CuS/ZnO quaternary heterojunction photocatalyst was constructed through a facile microwave technique. The structure, morphology and optical properties were characterized and explored. The photocatalytic activity of CuO/Cu2O/CuS/ZnO quaternary composite was assessed by antibiotic sulfamethoxazole under the simulated solar light irradiation. The quaternary composite manifested more excellent photocatalytic performance than the pristine ZnS and CuO/Cu2O. Moreover, the effects of ascorbic acid concentration on removal efficiency of sulfamethoxazole were discussed, revealing the importance of Cu2O in sulfamethoxazole removal. Particularly, as the ascorbic acid was 0.50 M, the total removal efficiency of sulfamethoxazole at an initial concentration of 20 mg/L was approximately 99.17 %, and the fitted pseudo-first-order kinetic rate constant reached 0.0380/min, which were 1.73 and 6.91 times of that in the absence of ascorbic acid, respectively. A double Z-scheme charge transfer mechanism was confirmed by the reactive species trapping tests, which demonstrated that superoxide radicals and holes were the major reactive species responsible for sulfamethoxazol degradation. CuO/Cu2O/CuS/ZnO nanocomposite provided an interesting perspective for a highly efficient quaternary photocatalyst that could be employed for remediation antibiotics.