A quadruple-functional photo-electrocatalyst for monitorable PCB-12 dechlorination during alkaline water splitting

The photo-assisted enhancement, as well as the multifunctional energy-environment synergy not only demonstrate substantial research significance in electrocatalytic materials but also pose considerable scientific challenges. In this study, we propose a quadruple-functional photo-assisted electrocatalytic (PEC) system for efficient and monitorable polychlorinated biphenyl (PCB-12) dechlorination during alkaline water splitting. The system comprises Ni(OH)₂S_x nanosheets decorated with NiS/Ni₃S₂ clusters and Ag₂S large nanoparticles (NPs) embedded with small Ag NPs. This integrated material demonstrates four distinct and efficient functions: 1) water splitting with current density of 1 A/cm² at 1.62 V vs RHE; 2) PEC dechlorination and degradation of 10⁻⁴ M PCB-12 within 50 h; 3) facilitation of Cl^- capture and hot electron injection from Ag₂S/Ag hetero-NPs; 4) monitoring of PCB degradation as in-situ surface-enhanced Raman spectroscopy (SERS) substrate. The results indicate that NiS/Ni₃S₂ is conducive to the retention of H*/OH*, while the H*/OH* on the Ni(OH)₂S_x is prone to desorption, makes the two active sites beneficial for PCB dechlorination and water splitting, respectively. This study provides a novel strategy for the collaborative application of multifunctional photo-electrocatalysts in energy conversion and environmental remediation.