Enhanced electron channel via the interfacial heterotropic electric field in dual S-scheme g-C3N4/WO3/ZnS photocatalyst for year-round antibiotic degradation under sunlight

Widespread and persistent presence of antibiotic contaminants in natural aquatic environments has aroused all mankind concern due to their potential threat to human health. Photocatalysis represents a promising means to remediate polluted waters with the simple assistance of solar energy. In this context, the feasibility of treating antibiotic contaminated water with g-C3N4/WO3/ZnS dual S-scheme heterojunction driven by interfacial heterotropic electric field was investigated under year-round climate conditions. The optimum composite (5-CWZ) could degrade >85% of tetracycline within 1 h of summer sunlight and 1.5 h of winter sunlight irradiation. The results of electron spin resonance (ESR), chemical trapping experiment, High performance liquid chromatography mass spectrometry (HPLC-MS), ultraviolet photoelectron spectroscopy (UPS) and density functional theory (DFT) calculation reflected that in-situ anchoring of WO3 and ZnS on the surface of g-C3N4 facilitates the formation of interfacial heterotropic electric field which were effective towards low-resistance charge carrier channelization, resulting sufficient •O2–, h+, •OH species evolving for attacking the active atoms of contaminants with high Fukui index. Furthermore, the retention of superior photocatalytic properties in complex actual water matrices together with the non-toxicity of both 5-CWZ photocatalyst and treated TC solution proved by Pisum sativum bud radicle elongation and bacterial (E. coli and B. subtilis) cultivation further demonstrated the feasibility of the 5-CWZ to treat antibiotics in real water under irradiation of solar light.