Sulfur-Doped Graphitic Carbon Nitride for Photocatalytic degradation of Congo Red Removal: Synthesis and Performance Analysis

This study explores the effective synthesis of sulfur-doped graphitic carbon nitride (S-doped g-C3N4) and its application in the photocatalytic degradation of the organic dye Congo Red (CR). By systematically varying the ratios of thiourea and urea during synthesis, the structural and photocatalytic properties of the resulting materials were optimized. Characterization via X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) confirmed that the S-doped g-C3N4 samples retained the characteristic crystal structure of pristine g-C3N4 while successfully incorporating sulfur atoms into the lattice. The iSCN1 sample exhibited superior photocatalytic performance, achieving a CR removal efficiency of 93.2% within 90 minutes in a 10 mg/L solution, outperforming undoped g-C3N4. Moreover, the addition of hydrogen peroxide H2O2 significantly enhanced the degradation rate, allowing iSCN1 to achieve 91.8% CR removal within just 60 minutes under comparable radiation exposure. Resutls from the radical trapping experiment revealed that hydroxyl radicals (•OH) generated during the photocatalytic process played a critical role in the CR decomposition reaction. The improvement in photodegradation efficiency results from the delocalization of lone electrons, which facilitates the separation of photogenerated charges, alongside the increased band gap of S-doped g-C3N4. These findings demonstrate the potential of S-doped g-C3N4 as an advanced photocatalyst for wastewater treatment applications and provide valuable insights into optimizing its synthesis for enhanced environmental remediation efficiency.