Abstract:
This study aims to investigate photocatalytic potential of graphene based ZnS nanocomposite under experimentally and computationally approach. The synthesis of graphite, GO and rGO used acid treatment, tour method, and chemical treatment, respectively. It used waste dry cell graphite rods for graphene source. Solution growth synthesis approaches were used to produce ZnS nanoparticles and ZnS/rGO nanocomposites. XRD, FTIR, DRS, PL, TGA, RAMAN SPECTROSCOPY and SEM-EDX characterization techniques were utilized for analysis. The experimental findings shown the successful synthesis of exfoliated black-brown rGO, light yellow ZnS nanoparticles, and a ZnS/rGO nanocomposite. Graphite shows a strong peak at a diffraction angle of 26.50, shifted to a lower angle of 25.20 in the case of rGO. Prominent peaks shown at 488 nm when excited at 280 nm for rGO. The transition from rough graphite sheets to smooth, flake-like surface morphology property of rGO was observed. The optical band gaps measured at 3.68 eV for ZnS decrease in to 3.051 eV for the ZnS/rGO nanocomposite because increase rGO concentration. The lower bandgap can be attributed to the formation of a nanocomposite. Similarly, TGA showed three stages of mass loss, and FTIR confirmed the presence of rGO in ZnS/rGO nanocomposite. The photocatalysis experiments were used 0.04 grams of ZnS/rGO, 80 ml MB (15ppm) solution with a pH of 12 under 300 w hydrogen lamp for 90 minutes. Regarding photocatalytic efficiency, ZnS/rGO-12wt % nanocomposites exhibited degradation percentages of 96.99 %. However, ZnS nanoparticles demonstrated a photodegradation efficiency of 70.74%. The enhanced photocatalytic activity shown at ZnS/rGO-12wt % nanocomposite. The photocatalyst shown good stability, with a degradation efficiency of 92.6 % and 86.8 % in first cycle and second, respectively. ALL the experimental results of ZnS/rGO nanocomposites show significant potential for photocatalysis application. Theoretical calculations used the CASTEP module in MATERIAL STUDIO to study the electronic and photocatalytic properties of ZnS/G heterostructures. The theoretical results suggest that the ZnS/G heterostructure exhibits enhanced adsorption capabilities as compared to ZnS. 3×3×1 graphene supercell with a 2×2×1 ZnS with 2.63% mismatch, the calculated band structures reveal a bandgap of 0.3 eV for ZnS/G and 2.7 eV for ZnS. Additionally, the major peaks of absorption coefficients of 8.6 × 10⁴, 17.8 × 10⁴ cm⁻¹ and 28.7 × 10⁴ cm⁻¹ which is indicating a reduced optical bandgap. The findings confirm that ZnS/rGO nanocomposite and ZnS/G heterostructures offer improved photocatalytic efficiency compared to ZnS catalysts.
