Characterization of a very thin overoxidized polypyrrole membrane: application to H2O2 determination

Abstract

AbstractIn the design of amperometric biosensor based on the electrochemical detection of enzymatically generated H2O2, an inert membrane is often present on the electrode in order to separate it from the solution to prevent interferences. The inert membrane could be an overoxidized polypyrrole film. Generally, the overoxidized polypyrrole films are obtained in two steps, the first one being the electrosynthesis of the polypyrrole film and the second one its overoxidation in an indifferent electrolyte. In this article, a new electrochemical one‐step process allowing the formation of a very thin overoxidized polypyrrole film is used. This film is characterized by SEM, XPS and cyclic voltammetry in the presence of monoelectronic reversible redox couples. Actually, the film is an electrical insulating compact layer about 10‐nm thick and pin hole free. This overoxidized polypyrrole membrane was tested on one hand for the rejection of anions and large molecules such as Fe(CN)63/4− and Ru(NH3)62/3+, respectively, and on the other hand, for the determination of hydrogen peroxide. The results show a very good efficiency of the membrane for the rejection of the redox species tested. Finally, it is shown that the membrane/Pt electrode allows quantitative electrooxidation of H2O2. Indeed, using this electrode, under potentiostatic condition, a linear response of the anodic current in function of the H2O2 electrolyte concentration was found. Copyright © 2010 John Wiley & Sons, Ltd.