Potential dependence of electrochemical impedance of nanoscale modified carbon fibre surface

Abstract

Poly(2,2-dimethyl-3,4-propylenedioxythiophene) (PProDOT-Me₂) thin films have been cyclovoltammetrically coated onto carbon fibre electrode as an active functionalised microelectrode. An electrochemical impedance study on the prepared electrodes is reported in the present paper under different applied potentials during electrochemical impedance spectroscopic measurements. The capacitive behaviour of the PProDOT-Me₂ coated carbon fibre microelectrode was investigated by cyclic voltammetry of polymer in monomer free solution which agreed with the capacitance obtained from electrochemical impedance spectroscopy. The film thickness for the cyclovoltammetrically prepared polymer film was in the range of about 30–50 nm. The electrochemical impedance data fitted two equivalent circuit models were used to find out numerical values of the proposed components. The effect of the deposition charge on the capacitive behaviour of the film was also investigated.

Keywords:

• ELECTROCOATING
• ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY
• POLY(2, 2-DIMETHYL-3, 4-PROPYLENEDIOXYTHIOPHENE)
• CARBON FIBRE SUPERCAPACITOR
• EQUIVALENT CIRCUIT