Z-scheme mpg-C3N4/Ag6Si2O7 heterojunction for highly efficient photocatalytic degradation of organic pollutants under visible light

Abstract

The mpg-C3N4/Ag6Si2O7 hybrid photocatalyst was successfully prepared via in situ precipitation of Ag6Si2O7 on mpg-C3N4 surface using a facile ultrasonic-assisted wet-chemical method and characterized by FE-SEM, TEM, HRTEM, XRD, FTIR, BET, XPS and UV–vis DRS analysis to study its morphology, composition, surface structure, chemical state and light absorption property. The effects of mass percentages of mpg-C3N4/(mpg-C3N4+Ag6Si2O7) on photocatalytic performence of the hybrid photocatalyst were investigated. The results showed that 4% mpg-C3N4/Ag6Si2O7 hybrid exhibited greatly improved photocatalytic activity for different organic dyes and colorless 2,4-dichlorophenol degradation under visible light and the photocatalytic degradation rate of MB by it attains 2.31 times that by sole Ag6Si2O7 and 51 times that by sole mpg-C3N4, and is also much higher than that by mechanical mixture of Ag6Si2O7 and mpg-C3N4 with the same mass percentage of mpg-C3N4, confirming the existence of the synergistic effect of Ag6Si2O7 and mpg-C3N4 in 4% mpg-C3N4/Ag6Si2O7 hybrid. High stability after three recycling runs under visible light was also observed. On the basis of the scavengers quenching experiments, PL and EIS determination, the XRD pattern and XPS spectrum of Ag3d in used 4% mpg-C3N4/Ag6Si2O7 hybrid after photocatalytic reaction, the highly efficient photocatalytic performance of 4% mpg-C3N4/Ag6Si2O7 can be clearly elucidated using the mechanism of Z-scheme heterojunction generated between mpg-C3N4 and Ag6Si2O7.