The preparation and aqueous electrochemistry of carbon paste electrodes modified by single wall carbon nanotubes and C-60 are reported. The matrix of carbon corresponds to an experimental turbostratic carbon black with low surface area. In all cases, the redox reactions studied by Cyclic Voltammetry in 6 M KOH can be assigned to the reduction/oxidation of intrinsic carbon-oxygen complexes and to the hydrogen adsorption/desorption reactions. Modification with less than 10 wt.` carbon nanotubes facilitates hydrogen evolution, while modification with C-60 causes the activation of the paste towards oxidation processes. For SWNT-modified paste electrodes, changes in the microstructure of the paste cause the increase in capacitive current, in contrast with the unmodified carbon paste electrode where this increment only occurs after several potential cycles. The fact that the paste electrode required an optimum carbon nanotubes concentration indicates that low-surface area carbon blacks are good candidates for the dispersion of single wall carbon nanotubes, and that a maximum of 200 increase in charge storage capacity can be obtained from carbon black/SWNT silicon oil composites. (C) 2005 Elsevier Ltd. All rights reserved.
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