High-Efficiency Visible-Light-Driven Ag 3 PO 4 /AgI Photocatalysts: Z-Scheme Photocatalytic Mechanism for Their Enhanced Photocatalytic Activity

High-efficiency visible-light-driven Ag 3 PO 4 /AgI photocatalysts with different mole fractions of AgI have been synthesized via an in-situ anion-exchange method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and UV–vis diffuse reflectance spectroscopy (DRS). Under visible light (>420 nm), the Ag 3 PO 4 /AgI photocatalysts exhibit enhanced photocatalytic activity compared to pure Ag 3 PO 4 or AgI for the degradation of methyl orange and phenol, and the highest activity is reached by the Ag 3 PO 4 /AgI hybrid photocatalyst with 20% of AgI. The quenching effects of different scavengers suggest that the reactive h + and O 2 •– play the major role in the MO degradation. Detailed X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analysis reveals that Ag nanoparticles (NPs) form on the surface of Ag 3 PO 4 /AgI in the early stage of the photocatalytic oxidation process, thus leading to the transformation from Ag 3 PO 4 /AgI to Ag 3 PO 4 /AgI@Ag. The excellent photocatalytic activity of the Ag 3 PO 4 /AgI photocatalysts can be ascribed to the efficient separation of photogenerated electron–hole pairs through a Z-scheme system composed of Ag 3 PO 4, Ag, and AgI, in which the Ag nanoparticles acted as the charge transmission bridge. The Ag 3 PO 4 /AgI hybrid remains good photocatalytic activity after five cycling runs.