Synthesis and photocatalytic performance of ZnS/rGO nanocomposites for methylene blue degradation

Abstract

This study focused on enhancing the photocatalytic performance of Zinc Sulfide through reduced graphene oxide by forming (ZnS/rGO) nanocomposites. Various characterization techniques included X-ray diffraction (XRD), FTIR, SEM–EDX, UV–Vis diffuse reflection spectra (DRS), thermogravimetric analysis (TGA), and photoluminescence spectroscopy (PL) were used to study various properties of the prepared nanocomposites. Successful synthesis and uniform distribution of ZnS nanoparticles on rGO sheet were confirmed through SEM, and dye degradation monitored by UV–Vis spectroscopy. Increasing rGO content improved crystallinity, as indicated by sharper XRD diffraction peaks around 27 , indexed to the (100) plane. The PL spectra further indicated that the enhancement in electron–hole generation within the nanocomposite was observed as the rGO content increased from 4wt% to 12wt%. The optical band gaps were determined to be 3.51 eV for ZnS and 3.68 eV for ZnS/rGO. The photocatalysis experiments were performed by adding 0.04 g of either pure ZnS or ZnS/rGO nanocomposite to 80 ml of an aqueous solution containing Methylene Blue dye at a concentration of 15 mg per liter (15 ppm), with a pH of 12 under 300 w hydrogen lamp. The presence of rGO enhanced charge separation, resulting in increased photocatalytic activity, with ZnS/rGO-12wt % achieving 96.99% degradation after 90 min of light exposure. The photocatalyst showed good stability, with a degradation efficiency of 92.6% in the first cycle, dropping to 86.8% in the second. All the results are revealed that, ZnS/rGO nanocomposites show significant potential for degrading methylene blue (MB) pollutants under visible light.