Photocatalytic Activity of TiO(2)/g-C(3)N(4) Nanocomposites for Removal of Monochlorophenols from Water

This research employed g-C(3)N(4) nanosheets in the hydrothermal synthesis of TiO(2)/g-C(3)N(4) hybrid photocatalysts. The TiO(2)/g-C(3)N(4) heterojunctions, well-dispersed TiO(2) nanoparticles on the g-C(3)N(4) nanosheets, are effective photocatalysts for the degradation of monochlorophenols (MCPs: 2-CP, 3-CP, and 4-CP) which are prominent water contaminants. The removal efficiency of 2-CP and 4-CP reached 87% and 64%, respectively, after treatment of 25 ppm CP solutions with the photocatalyst (40TiO(2)/g-C(3)N(4), 1 g/L) and irradiation with UV–Vis light. Treatment of CP solutions with g-C(3)N(4) nanosheets or TiO(2) alone in conjunction with irradiation gave removal efficiencies lower than 50%, which suggests the two act synergically to enhance the photocatalytic activity of the 40TiO(2)/g-C(3)N(4) nanocomposite. Superoxide and hydroxyl radicals are key active species produced during CP photodegradation. In addition, the observed nitrogen and Ti(3+) defects and oxygen vacancies in the TiO(2)/g-C(3)N(4) nanocomposites may improve the light-harvesting ability of the composite and assist preventing rapid electron-hole recombination on the surface, enhancing the photocatalytic performance. In addition, interfacial interactions between the MCPs (low polarity) and thermally exfoliated carbon nitride in the TiO(2)/g-C(3)N(4) nanocomposites may also enhance MCP degradation.