Synthesis of direct Z-scheme g-C3N4/Ag2VO2PO4 photocatalysts with enhanced visible light photocatalytic activity

Direct Z-scheme g-C3N4/Ag2VO2PO4 photocatalysts with enhanced visible light photoactivity were successfully synthesized. Their crystalline structure, morphology, optical, and electrochemical properties were analyzed by X-ray diffractometry, scanning electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, and electrochemical measurements. The photocatalytic degradation activities of as-prepared samples were evaluated by the photocatalytic of methyl orange (MO) and phenol in the aqueous phase. Compared with pure g-C3N4 and Ag2VO2PO4, the composites exhibited the higher photocatalytic activity under visible light irradiation. The photoactivity of g-C3N4/Ag2VO2PO4-0.4 is nearly 4 and 3 times higher than Ag2VO2PO4 and g-C3N4 for removal MO, respectively. Based on experimental results, the mechanistic regarding the direct Z-scheme electron transfer from Ag2VO2PO4 to g-C3N4 was proposed. The electron injection from conduction band of Ag2VO2PO4 to valence band of g-C3N4 suppresses the fast recombination rate and prolongs the charge carrier lifetime, thereby resulting in improved photoactivity. Furthermore, the photostability and active species during the photocatalysis was investigated.