A new purification method of single-wall carbon nanotubes using H2S and O-2 mixture gas

A purification process of single-wall carbon nanotubes (SWNTs) combining bo th the acid treatment to remove metal particles and the gas-phase purificat ion to remove impurity carbon particles has been developed. Acid solution o f 3 M HCl was used to remove catalyst metal particles out of the arc-discha rge grown SNNWs. Thermal oxidation method using H2S-O-2 gas mixture was fol lowed to preferentially remove carbon particles. Hydrogen sulfide played a role of enhancing the removal of carbon particles as well as suppressing th e oxidation of nanotubes. After the combined liquid-gas cleaning process. w e achieved carbon nanotubes purity of >95% with yield of 20-50%. (C) 2001 E lsevier Science B.V. All rights reserved.