The problem of purifying single-walled carbon nanotubes

Various techniques for the purification of single-walled carbon nanotubes (SWNT), are discussed. SWNTs synthesized by arc-discharge process contain a large proportion of amorphous carbon and metal nanoparticles. A procedure based on acid washing followed by air-oxidation at 300°C, hydrogen treatment at 800°C, and ending again with acid washing is able to yield near-pure SWNTs containing some residue due to metal particles. A procedure for purification of SWNTs, involve the refluxing in HCL, CO2 treatment, followed by acid washing at room temperature, and H2 treatment at 800°C followed by acid washing. The product was examined examined by transmission electron spectroscopy, TGA, Raman spectroscopy, and visible-NIR spectroscopy. This procedure has been shown to be very effective for the purification of SWNT.