Chirality-dependent combustion of single-walled carbon nanotubes

The chirality-dependent combustion of single-walled carbon nanotubes (SWCNTs) during oxidation in both air and hydrogen peroxide was investigated using photoluminescence and Raman spectroscopy. Under air oxidation conditions, SWCNTs with a higher chiral angle and smaller diameter were observed to decompose more rapidly. The decomposition rate of each chiral index was determined from the reaction rate analysis, and it was found that the reaction is governed by a local curvature radius along the C-C bond. The reaction barriers for breaking the C-C bonds after cycloaddition with oxygen molecules were obtained for 10 types of SWCNTs using first-principles calculations. The barrier heights were found to depend on the local curvature radius, which showed good agreement with the experimental results. On the other hand, for the oxidation reaction in hydrogen peroxide, oxygen radicals decomposed the smaller-radius SWCNTs more rapidly without any chirality selection. As a result, two different chirality distributions for SWCNTs with similar diameters were obtained by these oxidation processes.