Surface modification of TiO2 with g-C3N4 for enhanced UV and visible photocatalytic activity

g-C3N4 modified TiO2 composites were prepared through a simple calcination process of anatase and cyanamide. The as-prepared samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectrophotometry (DRS), fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), thermogravimetry differential thermal analysis (TG-DTA) and X-ray photoelectron spectroscopy (XPS), proving a successful modification of TiO2 with g-C3N4. Photodegradation of acid orange 7 (AO7) was used to evaluate the photocatalytic activities of the composites, showing excellent activity of them under both visible and UV light. In addition, base treatment was then introduced to investigate the interaction between g-C3N4 and TiO2. After removing the g-C3N4 modified on TiO2 by base, no nitrogen doping is found in TiO2 lattice, demonstrating the g-C3N4 was surface attached on TiO2 and attributing all improvement of photocatalytic activity of g-C3N4/TiO2 composite to the synergy between the two semiconductors.