A facile synthesis process of GCN/ZnO–Cu nanocomposite and the evaluation of the performance for the photocatalytic degradation of organic pollutants and the disinfection of wastewater under visible light

In this research, graphitic carbon nitride/zinc oxide-copper denoted as GCN/ZnO–Cu nanocomposite photocatalysts were synthesized using a novel facile synthesis process, the co-exfoliation method involving ultrasonic exfoliation of the mixture of GCN and ZnO–Cu in ethanol and then thermal exfoliation. Different characterization techniques such as X-ray diffraction (XRD), mean crystallite size (MCS), BET surface area, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), particle size distribution (PSD), Fourier transform-infrared spectroscopy (FT-IR), photoluminescence (PL) spectra, and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) were conducted to study the crystallinity, morphology, elemental composition, chemical structure, and optoelectronic properties. The band gap was estimated using the UV–Vis DRS results and Tauc plots. The photocatalytic activity of the GCN/ZnO–Cu3% nanocomposites was evaluated in the degradation of 4-chlorophenol (4-CP), and the disinfection of wastewater primary influent under a narrowband visible light source, royal blue LED (λ = 450 nm). GCN/0.1ZnO–Cu3% nanocomposite showed the best performance in the degradation of 4-CP and the disinfection of municipal wastewater primary influent. For 4-CP degradation, GCN/0.1ZnO–Cu3% was 2.2 times better than GCN, 9.4 times better than ZnO–Cu3%, and 1.8 times better than the sum of the individual GCN and ZnO–Cu3%. A 5.5 log reduction was achieved for the disinfection of total coliforms in wastewater primary influent in 360 min. This enhanced photocatalytic activity of GCN/ZnO–Cu3% nanocomposite can be attributed to the synergistic of GCN and the ZnO–Cu3%, resulting in a large surface area and improved bandgap.