Copper oxide nanoparticles with Sulfur-doped graphitic carbon nitride nanocomposite and its catalytic dye degradation

In this work, a composite of copper oxide and graphitic carbon nitride (CuO/S-g-C 3 N 4 NCs) were synthesized and their capacity to photocatalytically degrade methylene blue (MB) under visible light was assessed. CuO/S-g-C 3 N 4 NCs were synthesized by combining thermally polymerized S-g-C 3 N 4 with chemically precipitated CuO nanoparticles (CuO NPs) and characterized by UV–Vis, XRD, FT-IR, and SEM. Compared to pure CuO (2.72 eV) and S-g-C 3 N 4 (2.56 eV), the UV–Vis measurements verified a smaller band gap of 2.45 eV for CuO/S-g-C 3 N 4 NCs, suggesting better absorption of visible light. Under optimal experimental conditions (pH 10, 0.1 g/L catalyst dose, 10 mg/L dye concentration), photocatalytic tests demonstrated that the CuO/S-g-C 3 N 4 NCs exceeded the individual photocatalysts, achieving 95.1% degradation in 80 min. The greater photocatalytic performance is ascribed to effective electron–hole separation and less recombination due to the heterojunction interface. Reusability experiments confirmed the structural integrity of catalyst by showing consistent performance across several cycles. Generally, CuO/S-g-C 3 N 4 NCs exhibit great promise as effective photocatalysts for the treatment of wastewater under visible light.