FABRICATION OF CNTS BY TOLUENE DECOMPOSITION IN A NEW REACTOR BASED ON AN ATMOSPHERIC PRESSURE PLASMA JET COUPLED TO A CVD SYSTEM

Abstract

Here, we present a method to produce carbon nanotubes (CNTs) based on the coupling between two conventional techniques used for the preparation of nanostructures: an arc-jet as a source of plasma and a chemical vapour deposition (CVD) system. We call this system as an “atmospheric pressure plasma (APP)-enhanced CVD” (APPE-CVD). This reactor was used to grow CNTs on non-flat aluminosilicate substrates by the decomposition of toluene (carbon source) in the presence of ferrocene (as a catalyst). Both, CNTs and by-products of carbon were collected at three different temperatures (780, 820 and 860 °C) in different regions of the APPE-CVD system. These samples were analysed by thermogravimetric analysis (TGA and DTG), scanning electron microscopy (SEM) and Raman spectroscopy in order to determine the effect of APP on the thermal stability of the as-grown CNTs. It was found that the amount of metal catalyst in the synthesised CNTs is reduced by applying APP, being 820 °C the optimal temperature to produce CNTs with a high yield and carbon purity (95 wt. %). In contrast, when the synthesis temperature was fixed at 780 °C or 860 °C, amorphous carbon or CNTs with different structural defects, respectively, was formed through APEE-CVD reactor. We recommended the use of non-flat aluminosilicate particles as supports to increase CNT yield and facilitate the removal of deposits from the substrate surface. The approach that we implemented (to synthesise CNTs by using the APPE-CVD reactor) may be useful to produce these nanostructures on a gram-scale for use in basic studies. The approach may also be scaled up for mass production.

Keywords

• : Carbon nanotubes
• CVD
• Atmospheric pressure plasma
• Commercial arc-je