Improved solar-driven photocatalytic performance of Ag3PO4/ZnO composites benefiting from enhanced charge separation with a typical Z-scheme mechanism

In this work, efficient simulated solar-driven Ag3PO4/ZnO photocatalysts with different molar ratios of Ag/Zn have been prepared by a precipitation method and characterized by X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy and surface photovoltage (SPV) spectroscopy. Under simulated sunlight illumination, the Ag3PO4/ZnO composites exhibit enhanced photocatalytic activity compared with the pure ZnO toward the decolorization of rhodamine B (RhB) aqueous solution, and the Ag3PO4/ZnO composite with 4 % Ag/Zn molar ratio exhibits the highest activity. The quenching effects of scavengers indicate that O-2 center dot(-) plays the major role in RhB decolorization. Ag3PO4 deposited on the ZnO surface can promote the separation rate of photoinduced charge carriers, proven by the SPV results. Based on all the observations, the charge separation mechanism with a typical Z-scheme was proposed.