Controlled synthesises of ZnO nanoparticles using gas phase reaction

Abstract

Today, research and development on synthesis of nanoparticles becomes of interest global because of their excellent properties in catalytic, optical and magnetic functionality. Zinc Oxide (ZnO) is one of the most promising materials due to its attractive optical function based on a wide band gap of 3.37 eV. ZnO could be synthesized by various methods. Gas phase reaction route is one of potential means being utilized, providing higher purity with low operating cost and applicable at the industrial scale. In this research, the effects of synthesizing parameters on the size and the shape of ZnO nanoparticles were experimentally investigated. These parameters include evaporation temperature, oxidation temperature and gas flow rate. From the experimental results, it could be clearly observed that size and morphology of the ZnO nanoparticles are strongly dependent upon mixing ratio of zinc vapor and oxygen gas. ZnO nanoparticles were changed from a spherical shape to a tetrapod shape when the evaporation and oxidation temperatures were increased. In addition, the interaction between zinc vapor and oxygen was numerically verified by computational fluid dynamic (CFD) technique. FLUENT® was employed for calculating the concentration of zinc vapor and oxygen inside the reactor. In comparison with the experimental results, the use of a gas mixing apparatus (orifice) enhanced the interaction between zinc vapor and oxygen, resulting in uniform size and shape of ZnO nanoparticles.