Study on Preparation of Various Morphologies of ZnO Nanostructure through Wet Chemical Method

Abstract

Hydrothermal route and solution reaction method are adopted for the synthesis of zinc oxide (ZnO) nanopowders. Depending on precursors and preparation conditions, the obtained products possessed one of four following different morphologies: nanoparticle, microrod, nanoplate or nanotube. In this article, we report our investigation results of ZnO nanostructures preparation using a template-free aqueous solution based simple chemical route. Zinc nitrate hexahydrate Zn(NO3)2.6H2O was used as precursor for ZnO nanostructures. ZnO microrods and nanoplates were synthesized by a hydrothermal approach using Zn(NO3)2 and KOH as reaction chemicals. ZnO nanotubes were obtained by a chemical reaction of Zn(NO3)2 and NH4OH. And ZnO nanoparticles were prepared by precipitation method from zinc nitrate and ammonium carbonate (NH4)2CO3 in aqueous solution. The structures, morphology, and element components of these ZnO products fabricated by the above-mentioned methods were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). These experimental results demonstrated that the as-prepared ZnO nanoparticles have average diameter of 30-60 nm; rod-like ZnO has average diameter of about 350 nm and the length of 3.5 mm; plate-like ZnO has average thickness of about 40 nm and lateral size of 200´400 nm; ZnO nanotubes have outer diameter of about 400 nm and inner diameter of about 300 nm, the length of about 4 mm. The XRD results indicated that all four morphologies of ZnO are all wurtzite structure. It is found that the wet chemical technique is very promising for fabricating ZnO nanocrystallines with various morphologies. Our investigation makes useful contribution to the ZnO nanostructures studies, and can be used to explore potential applications in gas sensor, photocatalysts, surface enhanced Raman scattering (SERS) substrate and optoelectronic devices.