Carbon nanotube functionalization by atmospheric pressure plasma and post-plasma reactions

Abstract This study deals with the functionalization of multi-walled carbon nanotubes (MWCNTs) by a non-equilibrium atmospheric pressure plasma. A liquid spray containing MWCNTs is injected into the afterglow regime of the plasma in a specially designed reaction chamber. It is shown how the design of the reaction chamber and the type of liquid influence the MWCNT plasma interaction. Comparison of pristine and plasma treated nanotubes by X-ray photoelectron spectroscopy reveals that functionalization degrees up to 8 at.% of oxygen can be achieved and that hydroxyl, carboxyl and nitrogen containing functional groups can be generated on MWCNT surfaces. The role of radical reactions in the plasma process is studied by the interaction of plasma treated MWCNTs with the free radical diphenyl-picrylhydrazyl.