Boosting visible-light photocatalytic degradation of indomethacin by an efficient and photostable Ag3PO4/NG/WO3 composites

In our work, Z -scheme Ag 3 PO 4 /NG/WO 3 composites were fabricated via a facile deposition approach, which was used in the photocatalytic degradation of indomethacin (IDM) under visible light irradiation. The as-prepared Ag 3 PO 4 -based photocatalysts were characterized by X-ray diffraction analysis, scanning electron microscopy, transmission electron microscope , Fourier transform infrared, X-ray photoelectron spectroscopy and UV–visible diffuse reflectance spectroscopy in order to determine the chemical structure , morphological feature and optical performance. From the degradation experiments of IDM, the Ag 3 PO 4 /NG/WO 3 composite exhibited the highest photocatalytic activity and stability, and its kinetics constant was ~8 times of pure Ag 3 PO 4 . Furthermore, reactive species trapping experiment, electron spin resonance , liquid chromatography-mass spectrometry, total organic carbon , photoelectrochemical measurement and photoluminescence spectra were applied to analyze the possible degradation pathways and photocatalytic mechanism of IDM. The results indicated that the visible-light photocatalytic degradation of IDM using Ag 3 PO 4 /NG/WO 3 conformed to a Z -scheme photocatalysis mechanism, further facilitating the photoinduced charge carriers separation, and inhibiting the recombination of photoinduced electron-hole pairs. It also confirmed that the holes, OH and O 2 – radicals generated in Z -scheme system played the significant roles during the photocatalytic degradation of IDM.