Investigation on the structural, optical and photocatalytic degradation properties of Zns/Mn:Zns thin films under visible light irradiation

Abstract

Undoped and Manganese (Mn) doped Zinc Sulfide (ZnS) thin films have been prepared by using a simple sol–gel dip coating method and as-prepared ZnS thin films annealed at 400 °C at hot air furnace in order to improve crystallinity. The influence of Mn doping and annealing temperature on the structural, morphological, optical and photocatalytic behavior of the ZnS thin films under visible light irradiation has been scientifically investigated by using XRD, FESEM, UV–Visible and Photocatalytic analysis. XRD results suggest that prepared ZnS thin films formed hexagonal phase and crystallite size was calculated as 25 and 40 nm for ZnS and Mn:ZnS respectively. FESEM analysis shows that the nonoflake like morphology observed for undoped ZnS thin films annealed at 400 °C and this nonoflake like morphology further disappeared for Mn:ZnS thin films. An optical analysis confirm that the absorption edge shifts toward longer wavelength (red shift), which confirm that decreasing the band gap energy was observed for Mn:ZnS thin films. Besides, photocatalytic activity of methylene blue (MB) dye was investigated by using ZnS and Mn:ZnS thin films as catalyst under visible light irradiation. The result suggest that Mn:ZnS thin films exhibited excellent photocatalytic degradation efficiency (94%) and high stability towards MB dye than compared to pure ZnS thin films.