One-Step Electrochemical Synthesis of a Very Thin Overoxidized Polypyrrole Film

Generally, the electrochemical oxidation of pyrrole results in polypyrrole film in its doped conducting form. In this paper, it is shown that, in the presence of weak-acidic anions, pyrrole electro-oxidation leads to the formation of a very thin nonconducting overoxidized polypyrrole film. This phenomenon is due to the release of protons at the electrode/electrolyte interface during pyrrole oxidation. XPS analyses confirm ( i ) the film does not contain doping anions and ( ii ) the presence of carbonyl bonds; both features are characteristic of overoxidized polypyrrole.