Pyrrole was successfully electropolymerized at a copper-nickel electrode in a near-neutral sodium oxalate solution containing Cu2+ cations to generate a homogenous and adherent polypyrrole film. The presence of the Cu2+ ions increased both the rate of the electropolymerization reaction and the adherence of the polymer at the CuNi interface. In the absence of these cations, oxidation of the electrode occurred generating a nickel-rich layer that was not sufficiently conducting, under the electropolymerization conditions employed, to facilitate the electron-transfer reaction and the electropolymerization of pyrrole.
These films remained stable and exhibited significant corrosion protection properties in acidified and neutral 0.1 mol dm(-3) NaCl solutions even on polarization of the electrodes to high anodic potentials. (C) 2003 Elsevier Ltd. All rights reserved.