Simple non-basic solution route for the preparation of zinc oxide hollow spheres

Despite considerable efforts undertaken in a rapidly developing area of materials research, controlled synthesis of nanostructured ZnO is still a matter of intensive research. Herein, we report a facile base free approach for the fabrication of nanostructured ZnO hollow spheres. In the synthesis, ethylene glycol has been introduced as solvent and crystal-growth modifier and zinc acetate has been used as zinc precursor and also a source of soft template. ZnO nanoparticles of diameter similar to 25 nm are assembled into highly regular hollow spheres. The powder X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL) and UV-visible spectroscopy have been used to characterize the crystal structure, morphology, composition and optical properties. Powder XRD pattern of ZnO confirms the formation of the wurtzite structure. Presence of oxygen deficiency in the prepared ZnO product is revealed by Raman and EDS studies. Strong emission at 422 nm with three weak emissions at 400, 484 and 529 nm were observed by PL spectrum. The growth mechanism for the formation of ZnO hollow spheres has been discussed on the basis of the growth model for the polar ZnO crystals. (c) 2012 Elsevier B.V. All rights reserved.