Experimental Evaluation of Electrocatalytic Activity by Means of Thin Film-Coated Rotating Disk Electrodes

Abstract

Electrocatalysis of the reduction of oxygen and ethylenediaminetetraacetatoiron(III) complex was observed with the pyrolytic graphite electrodes coated with an intermolecular complex of poly(xylylviologen) polysulfonate. This coating film had high permeability to oxygen, so that every active viologen radical site of the polymer film could participate in the redu ction of oxygen. On the other hand, the reduction of the ethylenediaminetetraacetatoiron(III) complex which is catalyzed by viologen radical occurred in the vicinity of the polymer fil m/solution i nterface, since the Fe complexes can barely penetrate into the polymer film. The rate constants of the electron transfer cross-reaction between viologen active sites of the coating fil m and the substrates were determined from the detailed analysis of the stead y-state current potential curves which were obtained at the viologen-coated rotating disk electrode. Furthermore, the electrodes coated with the protonated poly(4-vinylpyridine), into which anionic metal complexes such as [W(CN)₈]^-4 were incorporated by electrostatic interaction, were prepared and the ability of the resulting film as a catalyst for the redox reaction of the Fe²⁺/³⁺ ion was examined.