Incorporation of N–ZnO/CdS/Graphene oxide composite photocatalyst for enhanced photocatalytic activity under visible light

N–ZnO/CdS/Graphene oxide (GO) composite photocatalysts have been successfully synthesized by hydrothermal method. The as-prepared composite photocatalysts were characterized by X-ray diffraction (XRD), Raman, scanning electron microscopy(SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FT-IR) spectra, UV–vis diffuse reflectance spectra (UV–vis DRS), thermogravimetry (TG) and photoluminescence (PL). The as-prepared photocatalysts exhibited strong visible light photocatalytic activity toward to degradation of antibiotics under ambient conditions. Particularly, the N–ZnO/CdS/GO composite photocatalysts showed the higher photocatalytic degradation rate (86%) of ciprofloxacin CIP under visible light irradiation than the pure photocatalysts. Compared with degradation of different antibiotics (tetracycline (TC), oxytetracycline hydrochloride (OTC-HCl) and levofloxacin (LEV)), the N–ZnO/CdS/GO composite photocatalysts also exhibited high photocatalytic activities. According to the experiments, the role of GO in the composite photocatalysts acted as an electron conductor, and also enhanced the separation rate of electrons and holes which greatly improved the photocatalytic activity. Lastly, the mechanism of enhanced photocatalytic degradation of CIP was also discussed.