Novel magnetic CoFe 2 O 4 /Ag/Ag 3 VO 4 composites: Highly efficient visible light photocatalytic and antibacterial activity

Visible-light-driven magnetic CoFe2O4/Ag/Ag3VO4 photocatalysts with different weight ratios of CoFe2O4 were successfully synthesized by a hydrothermal method. The as-prepared samples have been characterized by X-ray diffraction (XRD), infrared (IR), scanning electron microscopy with an energy-dispersive X-ray spectroscope (SEM-EDS), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Ultraviolet–visible absorption spectroscopy (UV–vis) and vibrating sample magnetometer (VSM). The photocatalytic experiments indicate that the CoFe2O4/Ag/Ag3VO4 composites possess enhanced visible-light-driven photocatalytic activity towards the degradation of methyl orange (MO), tetracycline (TC) and killing Escherichia coli (E. coli). Electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) spectra analysis indicate that the introduction of CoFe2O4 could efficiently promote the separation efficiency of photogenerated charge carriers in Ag/Ag3VO4. It is obvious that the composites show better photocatalytic activity than the pure Ag/Ag3VO4 and CoFe2O4. In particular, the 5% CoFe2O4/Ag/Ag3VO4 sample shows the highest photocatalytic activity and the degradation constant of 5% CoFe2O4/Ag/Ag3VO4 is as high as 3.4 times to that of Ag/Ag3VO4. The trapping experiments show that O2− and h+ are the major reactive species for the CoFe2O4/Ag/Ag3VO4 photocatalytic system. In addition, the as-prepared CoFe2O4/Ag/Ag3VO4 composite can be quickly separated from the solution by an extra magnetic field after the photocatalytic reaction. The cyclic test and the XRD patterns before and after cyclic test show that the CoFe2O4/Ag/Ag3VO4 hybrid materials have the stable degradation ability and crystal structure during the photodegradation process. Furthermore, it shows highly efficient visible light photocatalytic antibacterial activity. In all, the CoFe2O4/Ag/Ag3VO4 photocatalyst, as the magnetic photocatalyst and antibacterial, is promising for the further practical application of photocatalysis in wastewater treatment.