Stabilizing single-walled carbon nanotubes by removal of residual metal catalysts

We demonstrate that the removal of residual metals can dramatically enhance the stability of single wall carbon nanotubes (SWCNTs). Metal catalysts are used in SWCNTs synthesis, and residual metals remain in the nanotube preparations. Here we studied the gas phase oxidation of SWCNTs and their metal-free counterpart at high temperatures. After metal removal, the activation energy for oxidation increased by 50% and the frequency factor by nearly four orders of magnitude. This increase in thermal stability was also supported by the fact that the temperature corresponding to the onset of oxidation for metal-free SWCNTs was 135 °C higher than the one containing residual metals.