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 multistage purification method has been investigated. Sample purity is documented by ESEM, TEM, TGA, Raman and UV-vis-near-IR spectroscopy. Metal catalyzed oxidation at low temperature has been shown to selectively remove non-SWNT carbon and permit extraction of iron with concentrated HCL Prolonged catalyzed oxidation has been found to preferentially remove smaller diameter tubes. The onset of oxidation of purified smaller diameter HiPco SWNTs is also found to be approximately 100 degreesC lower than for purified larger diameter tubes produced in the laser-oven process.