Graphitic carbon nitride/titanium dioxide heterojunction for photocatalytic dyes degradation: performance enhancement and mechanism investigation

The construction of heterojunctions is an outstandingly valid strategy to modulate the properties of semiconductors. In this work, an anatase titanium dioxide nanoparticles/graphite-phase carbon nitride composite photocatalyst (g-C 3 N 4 /TiO 2 NPs) was prepared via loading g-C 3 N 4 derived from high-temperature calcination of melamine onto nanospherical TiO 2 NPs prepared by hydrothermal. A series of characterizations, such as scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Ultraviolet–Visible diffuse reflectance absorption spectroscopy (UV–Vis DRS), were employed to study the surface morphology, crystal structure, and photoelectrochemical properties of the photocatalyst. Photocatalytic degradation experiments and cyclic stability tests were conducted to evaluate its performance in degrading rhodamine B (RhB) and methyl orange (MO). The advanced photocatalytic activity is owing to the synergistic interaction of g-C 3 N 4 and TiO 2 broadening the band gap and the formation of the Type-II heterojunction promoting separation of photogenerated charge. The optimized 20% g-C 3 N 4 /TiO 2 composite demonstrated outstanding degradation efficiency, achieving 98.6% RhB removal in 60 min and 99.0% MO removal in 70 min, indicating that the catalyst possesses excellent dye degradation capabilities.