| Abstract
| - A new scalable method for purification of single-wall carbon nanotubes (SWNTs) by using microwave heatingin air is developed. The microwaves couple to the residual metal catalyst, raising significantly the localtemperature leading to both the oxidation and rupturing of the carbon passivation layer over the metal catalystparticles. With this protective carbon coating weakened or removed, a mild acid treatment is then sufficientto remove most of the metal in the sample, leaving the nanotubes in tact. Using microwave processing and4 M HCl acid reflux for 6 h we were able to remove residual metal (Ni, Y) in arc-discharge SWNTs to alevel lower than 0.2 wt % (∼0.04 at. %). Results from transmission and scanning electron microscopy, Ramanspectroscopy, and thermogravimetric studies were discussed.
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