Characterisation and corrosion studies of steel electrodes covered by polypyrrole/phosphotungstate using Electrochemical Impedance Spectroscopy

Polypyrrole/PW12O403− hybrid material was electrosynthesised on carbon steel electrodes in acetonitrile medium. The coatings obtained were characterised by Electrochemical Impedance Spectroscopy (EIS). On free-standing polypyrrole films the electrical response was mainly due to ion–ion charge transfer resistance, with a value of 175 Ω cm2. A value of 2 × 10−5 S/cm was determined for the hybrid material conductivity. A charge transfer resistance about 7000 Ω cm2 was obtained due to steel/oxide interface. Corrosion tests showed an important improvement in the protection against corrosion when the carbon steel electrodes were coated by these polymeric films.