Mediated oxidation of hydroquinone on poly-N-ethylcarbazole: analysis of transport and kinetic phenomena by impedance techniques.

The oxidation of hydroquinone on Pt electrodes modified by electrosynthesized p-ethylcarbazole is studied in 5 M HClO4. Electrohydrodynamical and a.c. impedance measurements yield the redox capacitance of the film and electron diffusivity DE with reasonable dependence on the thickness. DE values near to 10-7 cm2 s-1 confirm the average conductivity of this polymer. Charge-transfer resistances in agreement with ? = 0.5 are measured. These results a posteriori justify the hypotheses put forward when developing the theoretical impedance model used for the analysis of the data.