Rapid photocatalytic dechlorination of polychlorinated biphenyls by Cu nanocluster-modified ZnIn2S4

This study explores the photocatalytic degradation of decachlorobiphenyl (PCB 209), a persistent organic pollutant, using novel Cu nanocluster-modified ZnIn 2 S 4 photocatalysts under visible light irradiation. Pure ZnIn 2 S 4 was synthesized via a hydrothermal method, and Cu clusters were deposited on its surface through electrostatic adsorption. The optimal Cu loading of 0.1% by mass achieved a 99.5% degradation rate of PCB 209 within 90 minutes, significantly outperforming pristine ZnIn 2 S 4 . The successful modification of Cu nanoclusters enhanced visible light absorption and charge carrier separation. The degradation kinetics were influenced by the solvent type, with N, N-dimethylformamide showing the highest degradation rate. The degradation process was primarily driven by photogenerated electrons. The reductive dechlorination of PCB 209 is selective and easily removed from its para- and meta-positions. Density functional theory calculations indicate that copper nanoclusters have a stronger affinity for chlorine in the para- and meta-positions, leading to the dechlorination selectivity of PCB 209. The 0.1% Cu/ZnIn 2 S 4 catalyst demonstrated excellent stability and recyclability, maintaining over 83% degradation efficiency after five cycles. This study highlights the potential of Cu-modified ZnIn 2 S 4 as an efficient and sustainable photocatalyst for the remediation of PCBs in environmental applications.