Electrodeposition of ZnS and evaluation of its electrochemical property

Cu-doped ZnS was synthesized as a new photocatalyst material by electrodeposition. We attempted to synthesize ZnS using electrolytic baths containing metal ions and various complexing agents, i.e. tartaric acid, citric acid, triethanolamine (TEA), and disodium ethylenediaminetetraacetic acid (EDTA-2Na). The crystalline properties, binding conditions, surface morphology, and chemical composition of the samples were examined by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and energy dispersive spectrometry, respectively. ZnS was synthesized from all electrolytic baths examined except that using malonic acid as a complexing agent. However, X-ray photoelectron spectroscopy suggested that metallic Zn was also present in the ZnS deposits. The band gap energy of ZnS prepared using EDTA as a complexing agent ranged from 3.4 to 3.5 eV, lower than the value of 3.6 eV for pure ZnS, indicating that metallic Zn present in the ZnS deposit reduced the band gap energy.