Purification of carbon nanotubes by dynamic oxidation in air

We describe a new approach to the purification of single-walled carbon nanotubes (SWCNTs), based on the selective oxidation of carbonaceous impurities by heating at a constantly increasing temperature (i.e. dynamic oxidation) in air. Using UV-VIS-NIR spectroscopy, Raman spectroscopy and transmission electron microscopy (TEM) we demonstrate the superior purity of dynamically oxidized SWCNTs. In addition to being faster than other methods, dynamic oxidation allows for an efficient removal of carbonaceous impurities without significant loss of nanotubes. It is hypothesized that the advantages of dynamic oxidation arise from the exposure of the raw material to a wider range of temperatures than in conventional isothermal oxidation.