Aqueous synthesis and characterization of nearly monodispersed ZnS nanocrystals

An ultrasound-assisted solution-phase process has been applied for the aqueous synthesis of zinc sulfide nanocrystals in the presence of 3-mercaptopropionic acid (3-MPA) as a capping agent. The synthesis procedure was carried out by using two reagents: zinc chloride and sodium sulfide. Spherical shaped nanoparticles were agglomerated in the form of nanoclusters were observed. Obtained crystalline materials were found without the need of a post-synthesis treatment. The preparative conditions such as precursor concentrations, pH, and washing materials were optimized. The average crystalline size of ZnS nanostructures has been analyzed by X-ray diffraction (XRD) pattern and estimated to be 4.7 nm. The energy dispersive X-ray analysis (EDAX) reveals the average atomic percentage of Zn/S was 50: 50, showing that the preparation is exactly stoichiometric. Optical measurements indicate a direct band gap of about 4.27 eV. There was observed a blue shift of about 0.57 eV, in comparison to its bulk value due to quantum confinement effects of electrons and holes. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim