Preparation of Cl-Doped g-CN Photocatalyst and Its Photocatalytic Degradation of Rhodamine B.

The increasing global demand for clean water is driving the development of advanced wastewater treatment technologies. Graphitic carbon nitride (g-CN) has emerged as an efficient photocatalyst for degrading organic pollutants, such as synthetic dyes, due to its exceptional thermo-chemical stability. However, its application is limited by an insufficient specific surface area, low photocatalytic efficiency, and an unclear degradation mechanism. In this study, we aimed to enhance g-CN by doping it with elemental chlorine, resulting in a series of Cl-CN photocatalysts with varying doping ratios, prepared via thermal polymerization. The photocatalytic activity of g-CN was assessed by measuring the degradation rate of RhB. A comprehensive characterization of the Cl-CN composites was conducted using SEM, XRD, XPS, PL, DRS, BET, EPR, and electrochemical measurements. Our results indicated that the optimized 1:2 Cl-CN photocatalyst exhibited exceptional performance, achieving 99.93% RhB removal within 80 min of irradiation. TOC mineralization reached 91.73% after 150 min, and 88.12% removal of antibiotics was maintained after four cycles, demonstrating the excellent stability of the 1:2 Cl-CN photocatalyst. Mechanistic investigations revealed that superoxide radicals (·O) and singlet oxygen (O) were the primary reactive oxygen species responsible for the degradation of RhB in the chlorine-doped g-CN photocatalytic system.