Purification and characterization of single-wall carbon nanotubes (SWNTs) obtained from the gas-phase decomposition of CO (HiPco process)

A purification method is given for extracting the Fe metal catalyst and non -SWNT carbon from nanotubes produced by the HiPco process. (1,2) A multista ge purification method has been investigated. Sample purity is documented b y ESEM, TEM, TGA, Raman and UV-vis-near-IR spectroscopy. Metal catalyzed ox idation at low temperature has been shown to selectively remove non-SWNT ca rbon and permit extraction of iron with concentrated HCL Prolonged catalyze d oxidation has been found to preferentially remove smaller diameter tubes. The onset of oxidation of purified smaller diameter HiPco SWNTs is also fo und to be approximately 100 degreesC lower than for purified larger diamete r tubes produced in the laser-oven process.