Vertically aligned multi-walled carbon nanotube ensembles were exposed to argon and hydrogen ion bombardment in order to introduce defects into the structure. Raman spectroscopy and electrochemical analyses were then used to characterize the amount and nature of the disorder within the carbon nanotubes. While increased disorder upon ion irradiation was generally observed, argon and hydrogen had differing effects upon the Raman intensity spectra. Argon irradiation appeared to produce charged defects, in the form of dangling bonds, and increased the in-plane correlation length. Hydrogen bombardment passivated residual defects and decreased the correlation length. It was noted that hydrogen-treated carbon nanotubes could serve as electrochemical sensors with faster response times.

Artificial Introduction of Defects into Vertically Aligned Multiwalled Carbon Nanotube Ensembles: Application to Electrochemical Sensors. J.A.Nichols, H.Saito, C.Deck, P.R.Bandaru: Journal of Applied Physics, 2007, 102[6], 064306