Preparation, characterization, and photocatalytic activity of solar light sensitive g-C3N4/TiO2 nanocomposites

Solar light sensitive 2-dimensional (2D) graphite carbon nitride (g-C3N4)/titanium dioxide (TiO2) heterojunction nanocomposites were prepared to enhance visible light activity of TiO2. Preparation of the nanocomposites was accomplished by hydrothermal growth of TiO2 nanoparticles on the surfaces of g-C3N4 particles in one step. The g-C3N4 content of the composites varied from 20 to 90 wt%. The composite containing 80 wt% g-C3N4 was additionally subjected to a regulated heat treatment at temperatures in the range from 350 to 500 oC for 1 h to improve the photocatalytic activity. The interface and microstructural features of the nanocomposites were characterized by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and Diffuse Reflectance Spectra (DRS) techniques. The Methylene Blue (MB) degradation tests were performed to evaluate the photocatalytic activity of the powders under solar light illumination using a UV-vis spectrophotometer. Results were compared with the results of the pristine TiO2 and g-C3N4 powders. The g-C3N4/TiO2 heterojunction nanocomposites exhibited better photocatalytic activity for the degradation of MB than pristine TiO2 and g-C3N4 powders. An improvement in photocatalytic activity due to the generation of reactive oxidation species induced by photogenerated electrons and to the reduced recombination rate for electron-hole pairs was recognize