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

Abstract

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.