Synthesis, characterization and photocatalytic applications of Ag2S/g-C3N4/TiO2 nanocomposite

In this study, Ag2S/g-C3N4/TiO2 nanocomposite containing silver sulfide (Ag2S), graphitic carbon nitride (g-C3N4) and titanium dioxide (TiO2) nanoparticles was prepared by hydrothermal method. The morphology, crystal structure, elemental composition and chemical bond structure analysis of the prepared Ag2S/g-C3N4/TiO2 nanocomposites characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques, respectively. The photocatalytic activity of the synthesized nanocomposite was successfully tested for Crystal violet (KV) and Rhodamine B (RhB) dyes as model pollutants under UVA irradiation. The effects of catalyst amount on photodegradation with KV and RhB dyestuffs were investigated in the photocatalytic studies. In the presence of Ag2S/g-C3N4/TiO2 nanocomposite as photocatalyst, the initial dye concentration of 5 mgL-1, the catalyst amount of 25 mgL-1, and the percentage of degradation in KV and RhB after 120 minutes of UVA irradiation were obtained as 72% and 68%, respectively. In order to determine the contribution of reactive species in the photocatalytic degradation of Ag2S/g-C3N4/TiO2 nanocomposites and to suggest a possible mechanism, radical scavenging experiments were performed. Isopropanol, L-ascorbic acid and ethylenediaminetetraacetic acid (EDTA) were used to scavenger hydroxyl radicals, superoxide radicals and photogenerated holes, respectively. Scavenging experiments showed that hydroxyl radicals (.OH) and vacancies (h+) have a significant effect on the photodegradation of KV, while superoxide radicals (∙O2-) play a major role in the photodegradation of RhB.