Electrochemical activation of carbon nanotubes

This paper reports on the electrochemical pretreatment of multi-walled carbon nanotubes (CNT) prepared by different processes. While the anodic pretreatment results in a dramatic improvement in the electrochemical reactivity of the ARC-produced CNT, CNT produced by chemical vapour deposition (CVD) appear to be resistant to the anodic activation. Such a dramatic difference in the pretreatment effect upon ARG and CVD-produced CNT is illustrated using NADH, ascorbic acid, hydrazine and hydrogen peroxide model redox systems. The influence of the pretreatment potential and time is examined. Differences in the effect of the electrochemical pretreatment are attributed to the anodic preanodization effectively 'breaking' the basal-plane end caps of ARC-CNT thereby exposing edge plane defects, similar to those already present in the open-end caps of CVD-CNT. The new data offer a better understanding of the electrochemical reactivity of CNT and are consistent with the nature of the electroacatalytic properties of CNT. (C) 2004 Elsevier B.V. All rights reserved.