Preparation and Performance of Ag3PO4/Ag2S/g-C3N4 Composite Photocatalyst

Ag3PO4/Ag2S/g-C3N4 composite photocatalysts were successfully prepared by a deposition -ion exchanged combined method. And the obtained samples were characterized by X-ray powder diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N-2 adsorption and desorption isotherms, UV-visible diffuse reflectance spectroscopy, fluorescence spectrophotometry and so on. The catalytic activity and stability of the catalysts were evaluated by degradation of rhodamine B under visible light. The effect of molar ratio of sodium sulfide to silver phosphate (n(Na2S)/n(Ag3)PO(4)) on the photocatalytic performance of the silver phosphate was studied. In addition, the photocatalytic mechanism was also investigated. The results show that, with the increase of n(Na2S)/n(Ag3)PO(4), the activity of the obtained composite catalytic material increased firstly and then decreased. When n(Na2S)/n(Ag3)PO(4) was 1.5%, the obtained ASC1.5 catalyst could completely degrade rhodamine B within 40 min under visible light irradiation, and also maintained high activity after five-cycle use. Compared with single silver phosphate, the activity and stability of Ag3PO4/Ag2S/g-C3N4 composite photocatalytic materials were significantly improved, which was mainly attributed to the increase of surface area and the presence of porous structure that enhanced separating efficiency of electron-hole pairs. The study of photocatalytic mechanism over the composite catalyst have shown that h+, center dot O2- and center dot OH were the main active species in the photocatalytic process. The order of the role of the above three species was: h(+)>center dot O2->center dot OH.