Electrochemical characterization of polypyrrole/cobalt ferrite composite films for oxygen reduction

摘要

Electrodeposited films of polypyrrole(PPy)and composite of PPy and CoFe_2O_4 nanoparticles,incorporated with a charge compensating electrolyte anion(ClO_4~-)have been obtained on polished and pretreated graphite electrodes and characterized by cyclic voltammetry,impedance and cathodic polarization techniques.The study of films in a 0.8 mol dm~(-3)LiClO_4 + 5 mmol dm~(-3)KOH solution indicates that the porosity of the polymer matrix somewhat increases with incorporation of oxide nano-particles.The average apparent diffusion coefficient(D_a)of the dopant(ClO_4~-)has been observed to be approx2 times higher in the composite film compared to pure PPy film.The sum of the film and solution resistances,though higher for the composite electrode,remains practically constant under cathodic polarization conditions.In contrast to a non-composite electrode of the same oxide,the composite electrode exhibits much better electrocatalytic activity towards the O_2 reduction reaction.