Structural, morphological and optical characterization of green synthesized ZnS nanoparticles using Azadirachta Indica (Neem) leaf extract

Abstract

ZnS nanoparticles have been synthesized using various amounts of aqueous <em>Azadirachta Indica </em>(Neem) leaf extract as capping agent and stabilizer. The synthesized nanoparticles were studied by FTIR, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX) and UV-Visible spectroscopy. FTIR spectra shows that the biomolecules such as polyphenols, carboxylic acids, polysaccharide, amino acids and proteins present in the extract are responsible for the binding and stabilizing the synthesized ZnS nanoparticles. Analysis of the XRD data confirms the cubic structure of the synthesized materials with an average particle size of ~2 nm. Using XRD data the microstrain and dislocation density in ZnS crystals have been estimated. The particle size, strain and dislocation density are found to be affected by the amount of the extract used for synthesis. SEM and TEM studies were made to study the morphology and size of the particles. The EDAX spectra confirmed the presence of zinc and sulfur in single nanoparticle. UV-Visible spectra indicated a blue shift in the absorption peak for the extract-capped ZnS materials in comparison to the pure ZnS. The particle size of the ZnS nanoparticles estimated using UV-Visible spectral data along with those obtained from XRD analysis confirms that the green-synthesized ZnS nanoparticles lie in the range of quantum dots. The present study describes a simple, cost effective way of nanoparticle synthesis suitable for large scale production.