Nitrogen functionalization of MWCNTs in Ar-N₂ dielectric barrier discharge – Gas ratio effect

In this work, the effect Ar-N₂ mixture plasma on the surface characters and structure of MWCNTs were investigated. The plasma treatment was performed at various nitrogen gas ratio, while RF power, treatment time and gas pressure were kept fixed. The plasma species were monitored with optical emission spectroscopy. The X-ray photoelectron spectroscopy (XPS) confirmed the formation of nitrogen functional groups on the plasma- treated MWCNTs outer surface and its concentrations are dependent on the nitrogen gas ratio in the mixture plasma. The Raman analysis results are consistent with XPS observation. The MWCNTs surface roughness is enhanced as nitrogen gas ratio is increased in the plasma as observed by TEM and XPS images. The MWCNTs structure was not damaged as observed by XRD pattern. The correlations between the relative intensities of Ar-N₂ plasma species and the surface characters of the MWCNTs are also investigated.