Photocatalytic activity of La2O3-modified silver vanadates catalyst for Rhodamine B dye degradation under visible light irradiation

La2O3/Ag3VO4 samples were synthesized by impregnation process and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The XRD, SEM–EDS and XPS analyses revealed that La3+ was dispersed on Ag3VO4 in the form of La2O3 cluster. The DRS results indicated that the absorption edge of the La3+–Ag3VO4 catalyst shifted to longer wavelength. The enhanced photocatalytic activity of La2O3/Ag3VO4 for Rhodamine B (RhB) dye degradation under visible light irradiation was due to its wider absorption edge and higher separation rate of photo-generated electron and holes. The highest photodegradation efficiency was obtained when the La2O3/Ag3VO4 catalyst was calcined at 300 °C with 3 wt% La content. The photocatalytic degradation intermediates of the solution were identified by LC/MS.