AgI/Ag3PO4 heterojunction composites with enhanced photocatalytic activity under visible light irradiation

- Visible-light-induced AgI/Ag3PO4 sample has been synthesized by ion-exchange.
- The optimal activity of AgI/Ag3PO4 is 4.0 times as high as that of Ag3PO4.
- The heterojunction is favorable to improve the separation of electrons and holes.

AgI/Ag3PO4 hybrids were synthesized via an ion-exchange method. The structures and morphologies of the samples were characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL). The results showed that AgI nanoparticles were uniformly distributed on the surface of Ag3PO4 and the heterostructure was formed. DRS of the AgI/Ag3PO4 composites exhibited strong absorbance in Ultraviolet (UV) and visible regions. PL analysis indicated a more efficient separation of electron-hole pairs in the AgI/Ag3PO4 nanocomposites. Under visible light (λ > 400 nm), the photocatalytic activity of the AgI/Ag3PO4 composites for photodegradation of rhodamine B were efficient and much higher than that of the pure Ag3PO4 crystals. The enhancing photocatalytic activity of AgI/Ag3PO4 was attributed to the efficient separation of electron-hole pairs derived from the matching band potentials between AgI and Ag3PO4. A photocatalytic mechanism and the photocatalytic reaction kinetics over AgI/Ag3PO4 hybrid materials were also proposed.