The ohmic resistance effect for characterisation of carbon nanotube paste electrodes (CNTPEs)

Abstract

In this study, carbon nanotube paste electrodes (CNTPEs) have been characterised using their ohmic resistance, R_CNTPE, when examining a set of six different electrodes prepared from three types of CNTs and two altered pasting liquids (binders); the latter represented by traditional mineral or silicone oils. It is shown that simple measurements of the ohmic resistance can alternate to the standard electrochemical characterisation by cyclic voltammetry with model systems. During the proper experimentation, particular attention has been paid to the changes of the consistency and of the resultant R_CNTPE in dependence of both main constituents used and upon the carbon-to-pasting liquid ratio chosen. The results obtained were compared to those of “classical” carbon paste electrodes (CPEs) prepared from common graphite powder. The most evident and surprising difference ascertained is associated with the optimal carbon-to-pasting liquid: whereas the ordinary CPEs could contain up to 20% (w/w) oily phase, the CNTPEs reached the optimum at about 60% (w/w) binder, while retaining still satisfactory physical as well as electrochemical properties. The explanation of this finding is given and the problems connected with homogeneity and stability of various carbon pastes are discussed.