Tailoring the Electron Transfer Channel in an Internal Electric Field Induced by a Co ₉ S ₈ /ZnIn ₂ S ₄ Heterojunction To Boost Water Activation for Advanced Degradation of a Fluorinated Antibiotic

Effective fracture of the C-F bond is the key prerequisite for achieving advanced degradation of fluorinated antibiotics. Herein, a newly designed Co₉S₈/CQDs/ZnIn₂S₄ heterojunction with a strong internal electric field is synthesized and employed for photocatalytic ofloxacin degradation. Interestingly, introduced carbon quantum dots (CQDs) act as efficient charge transfer mediators to overcome the interface barrier of the heterojunction, thereby magnifying the internal electric field effect with an intensity enhancement of approximately 2.8-fold. More importantly, the enhanced hydrophilicity endows the Co₉S₈/CQDs/ZnIn₂S₄ heterojunction with presentable H₂O adsorption capacity, and adsorbed H₂O is then dissociated into OH^- and H⁺. Notably, photogenerated electrons can couple with H⁺ to trigger the fracture of the C-F bond, while photoinduced holes can activate OH^- to generate OH^• for realizing advanced mineralization of ofloxacin. Briefly, the Co₉S₈/CQDs/ZnIn₂S₄ heterojunction can directly activate water to achieve the degradation of ofloxacin under visible light irradiation. Furthermore, the intermediates generated during ofloxacin degradation and their toxicity are investigated in detail. Collectively, the current results can provide an important reference for further research on photocatalytic wastewater treatment.