g-C3N4/Ag3PO4 composites with synergistic effect for increased photocatalytic activity under the visible light irradiation

The g-C3N4 was synthesized by a hydrothermal method and the g-C3N4/Ag3PO4 composites were prepared by a ordinary precipitation method. Microstructures, morphologies and optical properties of the as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the Ag3PO4 nanoparticles were dispersed on the surface of the flake-like g-C3N4, and the heterojunction was formed on the interface. The g-C3N4/Ag3PO4 (2 wt%) photocatalyst presented the highest photocatalytic activity for organic dye methylene blue (MB) degradation, and its photocurrent intensity was approximately 2 times than that of the pure Ag3PO4. The g-C3N4/Ag3PO4 (2 wt%) photocatalyst also exhibited photocatalytic performance in the decomposition of colorless antibiotic ciprofloxacin (CIP). The capture experiment confirmed that holes acted as the main active species during the photocatalytic reaction.