Nondestructive purification of single-walled carbon nanotube rope through a battery-induced ignition and chemical solution approach

A two-step method for the purification of single-walled carbon nanotube (SWCNT) rope containing substantial catalyst particles embedded in carbonaceous shells was developed. The first step was the triggering of rope ignition using a 9-V battery, which resulted in pre-oxidization of the carbon shells on the Fe3C catalyst and oxidation of the exposed Fe3C to form Fe2O3. In addition, SWCNTs with open-end structures due to ignition-induced cutting remained. In the second step, both oxalic acid (H2C2O4) and hydrochloric acid (HCl) were used as the reactants to remove the Fe2O3 particles. No damage on the SWCNT walls after H2C2O4 or HCl purification was found. In addition, adsorption of H2C2O4 was also found on the H2C2O4 purified SWCNT rope and it can be effectively removed by heating the rope at 200 °C in vacuum for 40 min. Samples were characterized by SEM, TEM, Raman spectroscopy, TGA, FTIR, XPS, and UV–Vis–NIR.