Fabrication of novel g-C3N4 nanocrystals decorated Ag3PO4 hybrids: Enhanced charge separation and excellent visible-light driven photocatalytic activity.

Graphitic carbon nitride (g-C3N4) nanocrystals (NCs) decorated Ag3PO4 hybrids were synthesized by a facile method. The obtained samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), and UV-vis diffuse reflectance spectra (DRS). The SEM and TEM images showed that the as-prepared Ag3PO4 were composed of particles with diameters of 200-500nm, while the obtained nanocrystalline g-C3N4 were composed of smaller particles with average diameter of 10nm. For nanocrystalline g-C3N4/Ag3PO4 hybrids, the particle surfaces of Ag3PO4 were decorated with numerous g-C3N4 NCs, result in a larger contact area between g-C3N4 and Ag3PO4. The photocatalytic performances were evaluated by decomposing MO, phenol, bisphenol A, and RhB under visible light. Compared with Ag3PO4 and g-C3N4, the g-C3N4/Ag3PO4 hybrid (mass ratio=1:4) exhibited the best activity, which was much higher than that of bulk-g-C3N4/Ag3PO4 composite under the same conditions. The enhanced activities should be mainly ascribed to the enhanced separation efficiency of photo-generated carriers, which was proved by the photoluminescence (PL) spectra measurement. Controlled experiments proved that O2- and h+ played the chief role in the degradation process. A possible Z-scheme degradation mechanism of organic contaminant over g-C3N4/Ag3PO4 hybrid was proposed.