In-situ synthesis of Bi2WO6/AgBr/Ag4V2O7 with double Z-scheme heterojunction for oxytetracycline degradation and weakening toxicity

Herein, a novel Bi2WO6/AgBr/Ag4V2O7 double Z-scheme heterojunction photocatalytic material was synthesized by the ultrasonic-assisted coprecipitation method. When the content of AgBr in Bi2WO6/AgBr/Ag4V2O7 is 30 wt % and the content of Ag4V2O7 is 1 wt%, under the optimized reaction conditions, the degradation rate of Bi2WO6/AgBr/Ag4V2O7 to oxytetracycline (OTC) reached 88.13 % within 60 min, and the photocatalytic activity decreased only slightly after repeated use for three times, other than that, the toxicity of OTC to wheat decreased significantly after degradation. The morphology, composition, crystal structure and visible light absorption capacity of the samples are investigated by a series of characterization techniques. Furthermore, free radical capture experiment, electron paramagnetic resonance (EPR) experiment and liquid chromatography-mass spectrometry (LC-MS) were used to explore the possible photocatalytic mechanism and degradation path of OTC. The results show that the improvement of photocatalytic activity is attributed to the construction of a double Z-scheme heterojunction, which provides a more effective structural space for the separation of photogenerated e--h+ pairs. This study provides a new idea for the separation of photogenerated e--h+ pairs and broadens the response range of visible light, and proposes a new strategy for the environmental treatment of photocatalysts.