Novel magnetically separable g-C3N4/Fe3O4/Ag3VO4/Ag2CrO4 nanocomposites as efficient visible-light-driven photocatalysts for degradation of water pollutants

Novel magnetically separable g-C3N4/Fe3O4/Ag3VO4/Ag2CrO4 nanocomposites were successfully prepared by a facile refluxing method. The resultant samples were characterized using X-ray diffraction, energy dispersive analysis of X-rays, scanning electron microscopy, transmission electron microscopy, Fourier transform-infrared spectroscopy, thermogravimetric analysis, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and vibrating sample magnetometry. To evaluate photocatalytic activity of the resultant samples, photodegradation of rhodamine B (RhB) was investigated under visible-light irradiation. The results indicated that activity of the g-C3N4/Fe3O4/Ag3VO4/Ag2CrO4 nanocomposite with 20 % of Ag2CrO4 is about 15, 14, and 2.1-folds higher than those of the g-C3N4, g-C3N4/Fe3O4, and g-C3N4/Fe3O4/Ag3VO4 samples, respectively. Increase of the photocatalytic activity was attributed to increasing visible-light harvesting ability and separation of the photogenerated electron-hole pairs. Based on the effects of different scavengers on the degradation activity, the roles of the reactive species were described. Meanwhile, the possible mechanism for separation of the charge carriers was proposed and discussed. Significantly, the photocatalyst was separated from the treated solution using an external magnet.