Effect of Copper Inclusion in Zinc sulfide Thin Films for Photocatalytic Applications

Transparent and well-adhered pure zinc sulfide (ZnS) and different concentrations of copper-doped zinc sulfide thin films were obtained on glass substrates by the Chemical bath deposition process. Zinc acetate, copper acetate and thiourea were employed as sources of Zn2+, Cu2+ and S2- ions, respectively; ammonia and hydrazine hydrate served as complexing agents for the preparation of pure zinc sulfide and different concentrations of copper-doped zinc sulfide thin films. By adjusting the ammonia concentration, the prepared solution pH was maintained at 11. The prepared samples were deposited at the rates of 60 and 90 minutes each, with the bath temperature being held at 80 °C. The structural, morphological and optical properties of the prepared films were characterized by XRD, FE-SEM and EDX, and the results were reported. The XRD patterns revealed that all thin films possess a polycrystalline cubic zinc blended structure and that the prepared pure and copper-doped ZnS thin films have good crystallinity; the crystallite sizes were less than 20 nm. From the FE-SEM spectra, it is understood that the pure and Cu-doped ZnS thin films were uniformly coated with spherical morphology. The surface morphology, optical characteristics and deposition mechanism were all obviously impacted by the ammonia concentration. Additionally, under UV light irradiation, the effect of the photocatalytic property of the prepared thin films with methylene blue dye was studied and the corresponding dye degradation graphs were reported.