Preparation of Metallic Single-Wall Carbon Nanotubes by Selective Etching

Abstract

We report the bulk synthesis of a sample with a high concentration of metallic single-wall carbon nanotubes (m-SWCNTs) using a modified floating catalyst chemical vapor deposition method with methane as the carbon precursor. By tuning experimental parameters, such as species and flux of carrier gases, catalyst concentration, growth temperature, <i>etc</i>., small-diameter semiconducting SWCNTs (s-SWCNTs) and large-diameter m-SWCNTs were obtained. Using identical growth conditions, at a temperature of 1000 °C, it was found that the addition of hydrogen as an etchant gas resulted in the preferential removal of the smaller diameter s-SWCNTs. As a result, a sample enriched with large-diameter metallic SWCNTs was obtained. The self-assembled fishnet-like m-SWCNT network showed excellent optical transparency and electrical conductivity