Nitrogen-doped multiwalled carbon nanotubes (CNx MWNTs) have been cut to an average length of ∼1 μm by room-temperature acid treatment. Imaging of the surface morphology of the CNx, MWNTs (x = 2-5%) after sonication in acid or in ethanol (as a control) allowed the relationship between surface structure and acid cutting to be characterized. The effect of the acid treatment on the electrical conductance of the CN x MWNTs was also determined. The conductance of acid-treated CN x MWNTs was found to vary significantly within the sample and to be lower than the value of 1.0 G0 observed for as-produced CS x MWNTs. The G - V curves reported for acid-treated CNx MWNTs had an average slope of 0.19 G0/V, which is significantly smaller than the average of 0.70 G0/V measured for as-produced CNx MWNTs. Acid-treated CNx MWNTs exhibited a more rapid electrical breakdown with larger current steps, indicating the breakdown of several MWNT layers simultaneously. © 2008 American Chemical Society.
