Single-wall carbon nanotube paste electrodes: a comparison with carbon paste, platinum and glassy carbon electrodes via cyclic voltammetric data

A new carbon electrode material, obtained by mixing single wall carbon nanotubes (SWNTs) with a mineral oil binder is studied. Carbon nanotube pastes show the special properties of carbon nanotubes combined with the various advantages of composite electrodes such as a very low capacitance (background current) and the possibility of an easy preparation, modification and renewal. A better knowledge of the characteristics of electrode reactions at carbon nanotube paste (CNTP) electrodes was obtained studying the electron transfer rates of various redox couples under different pretreatment conditions. A critical comparison with carbon paste (CP), platinum (Pt) and glassy carbon (GC) electrodes was also carried out. Capacitance and resistance values were also calculated for all electrodes investigated. Both untreated and treated CNTP electrodes showed a low resistance while the capacitance was markedly reduced with CNTP electrodes previously treated with concentrated nitric acid. An electrochemical pretreatment on CNTP electrodes was developed which showed an excellent result towards two-electron quinonic structure species. After this treatment the heterogeneous standard rate constants for p-methylaminophenol sulfate (MAP) and dopamine resulted to be significantly higher (2.1 x 10(-2) cm/s and 2.0 x 10(-2) cm/s, respectively) than those obtained with the other electrodes studied. Reproducibility, stability and storage characteristics of CNTP electrodes were also reported.