Abstract:

Graphene oxide (GO) was fabricated from graphite powder by Hummers oxidation method and then, under ultrasonic irradiation, a series of GO/Ag₃PO₄ composite photocatalysts (4% (w, mass fraction) GO/Ag₃PO₄, 8% GO/Ag₃PO₄, 16% GO/Ag₃PO₄, 32% GO/Ag₃PO₄) were synthesized by a facile liquid deposition process. The products were characterized by N₂-physical adsorption, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra, Fourier transform infrared (FT-IR) spectroscopg, and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The effect of GO content on the photocatalytic activity of Ag₃PO₄ was evaluated by photocatalytic degradation of methyl orange (MO) under visible light irradiation. The results show that GO can be easily dispersed into Ag₃PO₄, producing a well-connected GO/Ag₃PO₄ composite. Coupling of GO largely enhanced the surface area of the catalyst and the adsorption of MO. At the optimal GO content (16%), the degradation rate of MO over GO/Ag₃PO₄ was 83% after 120 min of light irradiation, exhibiting 7.5 times higher activity than that of pure Ag₃PO₄. The increase in photocatalytic activity and stability can be mainly attributed to the coupling of GO, which increased the surface area and suppressed the recombination rate of electron-hole (e^-/h⁺) pairs and generated greater numbers of active free radicals.

Key words: Graphene oxide, Ag₃PO₄, Coupling, Photocatalytic activity, Methyl orange, Active free radical