Role of fuel's mixture on photocatalytic performance of g-C₃N₄/TiO₂ nanocomposites

In this study, the main objective was to improve the photocatalytic performance of TiO₂ and g-C₃N₄ under visible light irradiation by the creation of g-C₃N₄/TiO₂ heterojunction, where the solution combustion method was utilized to synthesize nanocomposites. The g-C₃N₄/TiO₂ nanocomposites were fabricated with a 9:1 wt ratio of g-C₃N₄ to TiO₂ for investigation of the effects of different fuels, including urea, glycine, citric acid, and their mixtures, on the photocatalytic performance of the g-C₃N₄/TiO₂ nanocomposites. The nanocomposites were characterized using various techniques such as diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, (BET) surface area analysis, field emission scanning electron microscopy (FESEM), Raman spectroscopy, and X-ray diffraction (XRD). The nanocomposite synthesized using a mixture of citric acid and urea (TCN-CA/U) depicted 97 % degradation of MB within 2 h of visible light exposure, demonstrating significantly enhanced photocatalytic efficiency. The degradation constant rate of TCN-CA/U (0.02971 min⁻¹) was approximately 3 times higher than that of pure g-C₃N₄ (0.00952 min⁻¹) and 13.5 times higher than that of TiO₂ (0.00218 min⁻¹). Furthermore, the TCN-CA/U nanocomposite showed high degradation efficiencies for Rhodamine B (RhB) (91 %) and Methyl Orange (MO) (61 %) under the same conditions. The observed improvement in photocatalytic performance attributed to several factors, including a fourfold increase in specific surface area (52.5 m²/g) compared to g-C₃N₄ (12.2 m²/g), a significant reduction in electron-hole pair recombination, and a narrowed band gap energy of 2.57 eV, which played a crucial role in enhancing visible light absorption.