A multi-structural carbon nitride co-modified by Co, S to dramatically enhance mineralization of Bisphenol f in the photocatalysis-PMS oxidation coupling system

The synthesis of Vis-light driven catalysts with high photocatalytic performance and efficient activation of persulfate requires new strategies. Herein, a multistage structural tuning graphitic carbon nitride co-modified by Co, S (pg-C3N4/Co3O4/CoS) was synthesized for the first time through in-situ template method and microwave sulfurization treatment. A photocatalysis-PMS oxidation coupling system was also proposed. The results showed that the introduction of cobalt could improve the photocatalysis and PMS activation efficiency of the graphitic carbon nitride. Further sulfurization treatment could generate more active sites for PMS activation and increase the interlayer distance of carbon nitride to broaden the absorption range of Vis-light. Density functional theory (DFT) calculations indicated the migration of electrons from carbon nitride to CoS promoted the recycling of Co3+/Co2+. In the coupling system, BPF 50 mL (30 mg L-1) was degraded by 99% in 10 min with 0.1 g L-1 catalyst and 0.32 mmol L-1 PMS. The degradation rate was 4 times faster than that of pure PMS system under visible light. Notably, BPF was effectively mineralized and TOC removal rate reached 90%. The stability and recycling experiments showed that pg-C3N4/Co3O4/CoS maintained high catalytic performance under complex matrix and multiple cycles, and could be quickly separated and recovered due to the magnetic Co3O4. This work will provide a new strategy for the development of multi performance catalytic materials, and the proposed photocatalysis-PMS coupling system has huge potential for the wastewater treatment.