Rapid Combustion Synthesis of Zinc Oxide Nanostructures

W. Merchan-Merchan, M. Farmahini Farahani
University of Oklahoma, US

Keywords: flame, nanorods, synthesis, TEM


In this contribution we show that Zn oxide nanostructures of various morphologies can be formed at high rates by using a counter-flow flame. A 1.0-mm in diameter Zn probes with a purity of ~99.99% is used as the metal source. The metallic probe, inside a protective chamber, is inserted into the oxygen-rich flame zone to form the Zn oxide nanostructures. The window size of the chamber was changed to synthesize Zn oxide structures of several morphologies on the surface of the probe. The formed structures are circular nanorods, nanorods containing pentagons and hexagons cross-sectional areas, and 3-D nanobead-like structures. Formed nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), High-resolution TEM (HRTEM) and energy disperse X-ray. We propose that the growth mechanism is composed of two different processes: 1) formation of vapors by the evaporation of the base metal as it is exposed to the flame medium. The Zn atoms are intercalated with oxygen atoms from the flame to form ZnO nuclei. 2) Once the nuclei are formed, elongated structures start to form through the vapor-solid (VS) growth mechanism.