Prompt and effective purification for thin single wall carbon nanotubes by dry process using ferric chloride

For the removal of iron catalyst nanoparticles, the dry purification of as-grown thin single wall carbon nanotubes (SWCNTs) with different mean tube-diameters of 0.9 and 1.3 nm by using FeCl3 was investigated. Based on the comparison studies on the purification efficiency and the various characteristics of these SWCNTs purified under different conditions, it was proved that the present dry-process can promptly proceed the purification reaction within a few 10 min with the high purity of more than 95 mass% as carbon content. Furthermore, the analysis of optical absorption spectra showed that the degradation of thinner SWCNTs with 0.9 nm diameter occurs on the dry purification at the temperature of higher than 900 °C even within the short duration (∼5 min) of FeCl3-treatment, while it is not observed in case of SWCNTs with 1.3 nm diameter.