Electrochemical Characterisations of Ultra Thin Overoxidized Polypyrrole Films Obtained by One-Step Electrosynthesis

Ultra thin (10-20 nm) and pin-hole free overoxidized polypyrrole films were directly electrosynthezised under potentiostatic conditions in the presence of weak-acid anions, specifically monohydrogenophosphate. Various overoxidized polypyrrole membranes were fabricated in these conditions at different potentials in the range of 0.70 to 0.90 V/SCE. Their non-conductive property and blocking character towards anions were verified by cyclic voltammetry and electrochemical impedance spectroscopy in the presence of the ferricyanide/ferrocyanide redox couple. The results show that these films are definitively ultra thin pine-hole free and non-conductive membrane. For comparison purposes, classical polypyrrole films were also prepared in the presence of perchlorate ions, overoxidized in KOH solution, and finally electrochemically characterized.