A novel emulsifier-free emulsion route to synthesize ZnS hollow microspheres

ZnS hollow microspheres were prepared via a novel emulsifier-free emulsion route for the first time. The aqueous solution of zinc nitrate and the toluene solution of thioacetamide were emulsified under sonication to form water in toluene emulsion, and then the emulsion was processed at elevated temperature under sonication for 45 min, by which ZnS nanoparticles were generated and assembled spontaneously at the surface of water droplets; after the subsequent separation, wash and desiccation process, ZnS hollow microspheres were obtained. ZnS hollow microspheres were characterized by TEM, XRD, UV-vis and particle size analyzer; the effect of the reaction temperature on the products was investigated. The results showed that ZnS hollow microspheres were made up of ZnS nanoparticles and had cubic structures (β-ZnS); with the rise of reaction temperature, the ZnS hollow microspheres became smaller and more compact. This study provided a promising route for the preparation of a variety of hollow microspheres.