Rapid and enhanced functionalization of MWCNTs in a dielectric barrier discharge plasma in presence of diluted CO2

Multiwalled carbon nanotubes (MWCNTs) have been functionalized in dielectric barrier discharge (DBD) plasma in presence of a mixture of carbon dioxide and a diluent gas at room temperature and atmospheric pressure. He, Ar, and N2 were examined as the diluent gases. Temperature-programmed desorption was used to investigate the influence of various plasma parameters and type of diluent gas as well as the amount of diluent in the plasma gas. It is found that the quantity of functional groups on the surface of MWCNTs is a maximum when He is used as diluent gas. It also passes through a maximum when He content is 60%. The presence of He improves the reactivity of the plasma, which leads to an increase in the quantity of functional groups. However, high percentages of He decrease the CO2 content, which in turn decreases the number of functional groups. FTIR and Raman spectroscopy showed the presence of Oxygen-containing functional groups on MWCNTs surfaces.