Enhancement of synergistic effect photocatalytic/persulfate activation for degradation of antibiotics by the combination of photo-induced electrons and carbon dots

Photocatalytic/persulfate-oxidation hybrid (PPSOH) system is considered as a feasible method for antibiotic degradation owing to it contains affluent active species. Herein, the flower-shaped ZnIn2S4 (ZIS) nanosheets modified by carbon dots (CDs) to form CDs-ZIS composite was selected as a catalyst for degradation of tetracycline (TC) in PPOH system. The degradation experimental results reveal that the optimal photocatalytic performance of 1% Vis/CDs-ZIS/persulfate (PS) system was achieved with TC (50 mg/L) removal rate of 83% within 120 min, which is attributed to the successful introduction of CDs that can effectively combine photo-induced electrons of ZIS to co-activate PS for enhancing photocatalytic degradation of TC. The active species capturing experiments exhibit that with the unique electron transfer property of CDs, the synergistic effect between photocatalytic and persulfate-oxidation was realized, in which persulfate was captured by electrons and generated plentiful sulfate radicals (SO4•-) and hydroxyl radicals (•OH). This work provides a new idea and strategy for CDs-based composite photocatalysts for the combination of photocatalysis and advanced oxidation.