Visible light driven antibiotics degradation using S-scheme Bi2WO6/CoIn2S4 heterojunction: Mechanism, degradation pathways and toxicity assessment

S-scheme heterojunction photocatalysts with strong redox ability and excellent photocatalytic activity are highly desired for photocatalytic degradation of pollutants. Herein, S-scheme Bi2WO6/CoIn2S4 heterojunctions were synthesized using hydrothermal method. The photo-induced carriers transfer mechanism of the S-scheme Bi2WO6/CoIn2S4 heterojunction was clarified by band structure analysis, ultraviolet photoelectron spectrometer (UPS), electron spin resonance (ESR) and radical trapping experiments. Significant enhance of light absortion, and more efficient carriers separation were observed from the Bi2WO6/CoIn2S4 with CoIn2S4 nanoclusters growing on the surface of petal-like Bi2WO6 nanosheets. TC degradation efficiency of 90% was achieved by Bi2WO6/CoIn2S4 (15:1) within 3 h of irradiation, and center dot O-2(-) and center dot OH radicals were dominated contributors. Possible decomposition pathways of TC were proposed, and ECOSAR analysis showed that most of the intermediates exhibited lower ecotoxicity than TC. This work provides reference on the constructing ternary-metal-sulfides-based S-scheme heterojunctions for improving photocatalytic performance.

Automated summary

In this study, S-scheme Bi2WO6/CoIn2S4 heterojunctions were synthesized and the photo-induced carriers transfer mechanism was clarified using various analysis methods. The results showed that Bi2WO6/CoIn2S4 with CoIn2S4 nanoclusters growing on the surface of Bi2WO6 nanosheets exhibited enhanced light absorption and more efficient carriers separation. A TC degradation efficiency of 90% was achieved by Bi2WO6/CoIn2S4 (15:1) within 3 hours of irradiation, with O-2(-) and OH radicals playing a dominant role. Additionally, possible decomposition pathways of TC were proposed, and most of the intermediates exhibited lower ecotoxicity than TC.