Fabrication of g-C 3 N 4 /TiO 2 photocatalysts with a special bilayer structure for visible light photocatalytic application

Photocatalytic technology is a new technique for environmental purification and solar energy conversions. The development of new and efficient photocatalysts has been a research hotspot for several years and the fabrication of composite photocatalyst has attracted wide attention. Herein, g-C3N4/TiO2 photocatalyst with a special bilayer structure has been synthesized under mild solvothermal conditions with TiO2 flake as the substrate material. The combination of TiO2 and g-C3N4 effectively increased the specific surface area of the composite and was conducive to the synergistic effect. The time of solvothermal reaction influences the binding mode of g-C3N4 and TiO2, which in turn affects the photocatalytic activity. The photodegradation rate of methylene blue (MB) by g-C3N4/TiO2 composite reached 97.61 % under visible light irradiation, which was 1.46 and 1.98 times higher than those of pure g-C3N4 and TiO2, respectively. The improvement of photocatalytic performance is mainly attributed to the enhanced separation efficiency of photogenerated electron-hole pairs caused by the construction of heterojunctions, which has been confirmed by electrochemical impedance spectroscopy and optical transient current spectrum. Furthermore, the main active species in photocatalytic system were determined by radical trapping experiments and the photocatalytic mechanism of the composite photocatalytic system was further speculated. © 2020 Elsevier B.V.