High yield non destructive purification of single wall carbon nanotubes monitored by EPR measurements

A chemical purification method has been developed which leads to highly pure and little damaged single wall nanotubes (SWNT) with a 55 to 65% overall yield. It combines a short and soft acid reflux with a hydrogen peroxide reflux. Electron paramagnetic resonance (EPR) measurements have been used to assess the residual amount of both catalyst and amorphous carbon. By this method, the acid treatment duration was minimized to 4 h, preserving the SWNT structure. EPR indicates a decrease of amorphous carbon content by up to a factor 3 with a 90 minutes peroxide treatment. As-purified SWNTs allow us to generate nanoscale electronic devices via self-assembling.