Nearly complete removal of zeolite particles and Fe/Co catalysts from raw single-walled carbon nanotubes (SWNTs) produced by chemical vapor deposition was achieved by oxidation of raw material at 240°C or 340°C and treatment with 1% aqueous solution of hydrofluoric acid. The yields of SWNTs were estimated to be ≈95% and the purities of SWNTs thus obtained were more than 95%, as characterized by thermo-gravimetric analysis. Raman spectra of the purified SWNTs were essentially identical with those of the corresponding raw samples. The raw and purified SWNTs were also characterized by EDX spectroscopy and transmission electron microscopy.
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