Tailoring multi-wall carbon nanotubes for smaller nanostructures

Efficient electrochemical treatments of multi-wall carbon nanotubes (MWCNTs) in acetonitrile were performed by cycling the applied potential on a carbon paper grown with MWCNTs between -2.000 V and 2.000 V (vs Ag/AgClO4) at a scan rate of 0.5 V/s. The tailored MWCNTs with obvious morphological modification could be further cut into short tubular structures through ultrasonic processing in ethanol. Various analytical techniques, including scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy, were used to probe the morphological and structural evolution of MWCNTs during the treatments. The length of the shortened tubular structures ranged from a hundred to a few hundred nanometers, depending on the electrochemical procedures applied. The deformed and shortened MWCNTs displayed a graphitic crystalline structure. These results suggest that repeated electrochemical oxidation and reduction processing of MWCNTs opens up a new route to controlling surface modification and cutting of MWCNTs, which will facilitate their application in areas such as energy storage, catalytic support, and biosensing. (C) 2008 Elsevier Ltd. All rights reserved.