Photocatalytic degradation mechanism of phenanthrene over visible light driven plasmonic Ag/Ag3PO4/g-C3N4 heterojunction nanocomposite

Visible light driven plasmonic Ag/Ag3PO4/g-C3N4 heterojunction nanocomposite with regular morphology was prepared via a modified facile method. The two-dimensional ultrathin g-C3N4 nanosheet is uniformly wrapped on the surface of Ag3PO4 nanopolyhedron. A charge transfer bridge was built between Ag3PO4 nanopolyhedron and g-C3N4 nanosheet due to the reduction of Ag nanoparticles. This structure can inhibit the recombination of photogenerated electron-hole pairs and promote the transfer of photogenerated carriers, so as to produce more active species for participating in the photocatalytic reaction. In addition, the surface plasmon resonance (SPR) of appropriate Ag nanoparticles enhanced the absorption and utilization of visible light. Compared with Ag3PO4 and Ag/Ag3PO4, Ag/Ag3PO4/g-C3N4 showed higher photocatalytic activity. Under visible light irradiation, the degradation rate of phenanthrene (PHE) was 0.01756 min(-1), which was 3.14 times and 2.38 times that of Ag3PO4 and Ag/Ag3PO4, respectively. After four cycles of photocatalytic reaction, the Ag/Ag3PO4/g-C3N4 photocatalyst still maintained high photocatalytic activity. The active sites of PHE were predicted by Gaussian simulation calculation and combined with intermediate products identification of GC-MS, the possible degradation pathway of PHE was speculated. This research has reference significance for the construction of plasmonic heterojunction photocatalyst in the field of environmental pollution remediation.