Trisodium citrate assisted synthesis of ZnO hollow spheres via a facile precipitation route and their application as gas sensor

To enrich the variety of zinc oxide, a facile trisodium citrate assisted alkaline precipitation route was developed to prepare ZnO hollow spheres with partial open gaps comprised of a mass of nanoparticles. The composition, morphology and structure of the product were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the final products were pure hexagonal phase (zincite), and the ZnO shell was composed of a polycrystalline aggregation of nanoparticles. Trisodium citrate played a crucial role as a capping agent in the formation of the ZnO hollow spheres. The ZnO with hollow morphology exhibited excellent gas response. This result indicated that the annealed ZnO with hollow sphere architecture is a promising candidate for gas sensing applications.