Fabrication of a double Z-type g-C3N4/AgBr/Ag3PO4 composite with enhanced visible-light photocatalytic activity for organic dye elimination

A novel double consequent Z-type g-C3N4/AgBr/Ag3PO4 composite photocatalyst was prepared by ultrasonic assisted in-situ precipitation method. The structure and properties of the samples were characterized by XRD, FTIR, XPS, SEM, TEM, UV-vis DRS, TRF and EIS. The obtained g-C3N4/AgBr/Ag3PO4 composites show better photocatalytic performance compared with pure Ag3PO4. When the initial concentration of methyl orange (MO) dye is 10 mg/L without adjusting pH, the 10%-g-C3N4/AgBr/Ag3PO4 photocatalyst (1 g/L) exhibits the best photocatalytic activity with the highest removal rate of 93.56% under visible light irradiation, which shows better reaction rate constant with 6.27 times than pure Ag3PO4. Besides, g-C3N4/AgBr/Ag3PO4 photocatalyst shows better stability than pure Ag3PO4 after repeated use for three times. The enhanced photocatalytic performance and stability of the g-C3N4/AgBr/Ag3PO4 catalyst can be attributed to the formation of the double Z-type heterostructure in the ternary composite, which promotes the separation of the photogenic carriers, thus increasing the photocatalytic activity and inhibiting the photocorrosion. In addition, the free radical trapping experiments further proved that center dot O(2)(-)and h(+) are the main active substances in the photocatalytic process. This study may provide an efficient and economical photocatalyst for the degradation of organic dyes.