Electron transfer behaviour of single-walled carbon nanotubes electro-decorated with nickel and nickel oxide layers

The electron transfer behaviour of nickel film-decorated single-walled carbon nanotubes (SWCNTs-Ni) at edge plane pyrolytic graphite electrodes (EPPGEs) was investigated. The impact of SWCNTs on the redox properties of the nickel film was investigated with cyclic voltammetry and electrochemical impedance spectroscopy (EIS). From EIS data, obtained using ferrocyanide/ferricyanide as a redox probe, we show that the electrodes based on nickel and nickel oxide films follow electrical equivalent circuit models typical of partial charge transfer or adsorption-controlled kinetics, resembling the "electrolyte-insulator-semiconductor sensors (EIS)". From the models, we prove that EPPGE-SWCNT-Ni exhibits the least resistance to charge transport compared to other electrodes (approximately 30 times 25 times faster than EPPGE-SWCNT, and over 300 times faster than the bare EPPGE) suggesting the ability of the SWCNTs to act as efficient conducting species that facilitate electron transport of the integrated nickel and nickel oxide particles. (C) 2008 Elsevier Ltd. All rights reserved.