Interfacial doping of carbon nanotubes at the polarisable organic/water interface: a liquid/liquid pseudo-capacitor

Abstract

The electrochemical reactivity of single-walled carbon nanotube (SWCNT) films, assembled at a polarisable organic/water interface, has been probed using model redox species. Electrons generated by the oxidation of organic 1,10-dimethylferrocene (DMFc) to DMFc+ can be transferred through the assembled SWCNT layer and reduce aqueous ferricyanide (Fe(CN)6 3 ) to ferrocyanide (Fe(CN)6 4 ), with a doping interaction observed. Several electrochemical techniques, including cyclic voltammetry and electrochemical impedance spectroscopy (EIS), were employed to confirm that the model redox couples dope/charge the SWCNTs. In situ Raman spectro-electrochemistry was also applied to verify the charge transfer processes occurring at the assembled SWCNT films and confirm that the doping effect of the carbon nanotubes is initiated by electrochemical reactions. This doping interaction indicated that the adsorbed SWCNT films can act as a pseudo-capacitor, showing a high area-normalised capacitance. The deeper understanding of the electrochemical properties of SWCNTs, gained from this study, will help determine the performance of this material for practical applications.