Zinc nanowires synthesized on a large scale by a simple carbothermal process

Abstract

Metallic Zn nanowires have been synthesized by a new carbothermal reduction route in which ZnO and Eucalyptus sp. tar pitch were used as source materials. This simple practical procedure was capable of producing Zn nanowires in large quantities without reoxidation. This process was carried out in inert atmosphere, without vacuum or catalyst, at temperatures (800–900 °C) lower than those required in the carbothermal reduction of ZnO with graphite. A comparative study was performed using graphite that is traditionally used as a ZnO reducer, under the same experimental conditions, however, no reaction was observed. The new process involves the pyrolysis of biopitch to obtain a highly reactive coke and the reduction of ZnO with the release of Zn (v) for the growth of Zn (s) nanowires. The resulting Zn nanowires were characterized by X-ray diffractometry, energy-dispersive spectroscopy and scanning electron microscopy. Differential thermal analysis and thermogravimetric analysis coupled with infrared analysis techniques were used in an effort to understand the underlying mechanism and establish the best ratio biopitch/ZnO to be used. This paper presents the characterization of the as-synthesized nanowires and discusses the main reactions involved in their production.