Facile synthesis of mesoporous carbon nitride and titanium dioxide nanocomposites with enhanced visible light photocatalytic activity

Abstract

A facile and efficient solution combustion method was developed and employed in the fabrication of novel mesoporous carbon nitride and titanium dioxide (C₃N₄–TiO₂) nanocomposites as advanced photocatalysts for wastewater remediation. Urea was used as the precursor of C₃N₄, while titanium tetra-isopropoxide served as the source of titanium. Yellow nanocomposites were produced as compared to the formed white TiO₂ and C₃N₄ nanomaterials. Transmission electron microscopic images and N₂ adsorption/desorption analysis revealed that the fabricated nanocomposites possessed a mesoporous structure and much larger surface areas as compared to the individual constituents. X-ray photoelectron spectroscopic measurements and thermogravimetric analysis were utilized to determine the composition and thermal stability of the C₃N₄–TiO₂ nanocomposites. Tauc plots derived from the UV-vis absorption spectra revealed that the formation of the C₃N₄–TiO₂ nanocomposites significantly narrowed the band gap energy, leading to a high visible light response in contrast to the individual TiO₂ (∼3.2 eV) and C₃N₄ (∼2.8 eV) samples. The optimal composition of the C₃N₄–TiO₂ nanocomposites was determined, and the new nanocomposite developed in this study exhibited high visible light activity in the photochemical oxidation of Rhodamine B, as compared to the mechanically mixed C₃N₄ and TiO₂ sample. This significant improvement in photocatalytic activity may be attributed to the synergistic effects of the red shift in absorption and the large surface area.