Photocatalytic Penicillin Degradation Performance and the Mechanism of the Fragmented TiO(2) Modified by CdS Quantum Dots

[Image: see text] In this study, a novel method was adopted to construct a CdS–TiO(2) heterostructure to degrade penicillin under sunlight. A potato extract was used during the synthesis process of CdS QDs as a stabilizer and a modifier. The CdS–TiO(2) composite with a heterostructure delivers high photocatalytic degradation efficiency. In detail, 0.6 mg/mL of CdS–TiO(2) can successfully decompose penicillin after 2 h, and 5‰ CdS–TiO(2) shows the optimal degradation efficiency with the degradation rate reaching 88%. Furthermore, the underlying mechanisms of the penicillin decomposition reaction were investigated by the EPR test and trapping experiment. It was found that the high photocatalytic degradation efficiency was attributed to the heterojunction of CdS–TiO(2), which successfully suppresses the recombination of the conduction band of CdS and the valence band of TiO(2). Moreover, it was confirmed that the reaction is the O(2)-consuming process, and introducing O(2) can greatly accelerate the generation of a superoxide radical during the photocatalytic degradation process, which eventually improves the degradation of penicillin and shortens the degradation time. Finally, this work provides the possible penicillin degradation pathways, which will inspire the researchers to explore and design novel photocatalysts in the field of wastewater treatment in the future.