Effect of silver doping on structural and optical properties of starch capped ZnS nanoparticles synthesized by microwave irradiation

Abstract

Cost effective facile method of synthesis of silver (Ag) doped zinc sulfide (ZnS) nanoparticles encapsulated by starch is reported in this communication. Synthesis involves chemical co-precipitation method using zinc acetate and thioacetamide as ZnS precursors, silver nitrate as dopant salt, starch as capping agent and water as solvent. Ag is an active metal which gets easily oxidized by the general methods of doping. The effect of efficient heating by microwaves has been utilized in the present work. Energy dispersive spectroscopy (EDS) analysis of the samples implied a solubility of Ag in ZnS lattice. The X-ray diffraction (XRD) patterns of the Ag doped samples retained the same cubic crystal structure as ZnS nanocrystals. Substitutional incorporation of Silver into the ZnS lattice is confirmed by positional shifts of XRD peaks. The mean size of the nanocrystallites calculated using Scherrer equation is about 3 nm. Raman spectra also implied the formation of nanoform of cubic ZnS. Energy band gaps are found to decrease in UV–Vis study for Ag doped samples. The absorption spectra of all samples show quantum confinement effect. The transmission electron microscopy (TEM) and Fourier transform infra red (FTIR) spectroscopy studies for the selected sample reveal that the synthesized particles were stabilized by starch as capping agent.