Zinc Oxide Nanopolypods Synthesized by Thermal Evaporation of Carbon Nanotubes and Zinc Oxide Mixed Powder

In this work, ZnO nanostructures synthesized by thermal evaporation of zinc oxide (ZnO) and carbon nanotubes (CNTs) on silicon substrate with sputtered Ag catalyst on are investigated. The multi-wall CNT powder made by chemical vapor deposition was mixed with ZnO powder with a ratio of 1:1 by mole. The mixture was then evaporated under argon flow in a horizontal tube furnace with source temperature of 950 C. Structural characterization by scanning electron microscopy showed that ZnO polypods including tripods, tetrapods, multipods with triangular nanobelts and nanoneedles extending from each leg were formed while short nanorod and nanoparticle ZnO structures were obtained by ZnO-graphite evaporation under the same condition. In addition, considerable carbon content in ZnO nanostructure was observed by energy dispersive x-ray spectrometry. Transmission electron microscopy and x-ray diffraction confirmed single crystal structure and dominant [101] crystal facet. Vapor-solid mechanism and oxidation in high carbonaceous ambient are proposed as mechanisms for the formation of ZnO polypod by ZnO-CNT thermal evaporation. Moreover, ZnO nanostructures have an interesting flat green luminescent band between 480 and 530 nm and plausible explanation based on carbon doping and multi-dimensional structure is proposed to be responsible for such characteristic.