Revisiting the Electrochemical and Polymeric Behavior of a Polypyrrole Free-Standing Electrode in Aqueous Solution

Abstract

A procedure to obtain homogeneous free-standing polypyrrole (ppy) films 10−20 μm thick is described. The resulting films have mechanical characteristics good enough to be used as a working electrode for electrochemical measurements and applications. Structures and uniformity of both film surfaces and the cross section were studied by SEM. Three different procedures were used to determine the film thickness. The free-standing film can be reduced in aqueous solution up to −3.0 V without any presence of hydrogen release or polymer degradation. Voltammetric experiments show the usual voltammograms, but they only involve a partial oxidation and reduction of the film capabilities: voltammetric charges increase for decreasing sweep rates. A deep reduction of the film is achieved by polarization times longer than 300 s at −0.6 V or more cathodic potentials. The second cathodic maximum, appearing on the voltammograms between −0.7 and −0.9 V, is related to slow kinetic and structural processes since the film reduc...