Electrochemical Behavior of Iron-Carbon Composites Prepared from Ferrocene-Poly (furfuryl Alcohol)

Iron-carbon composites were prepared by polymerization and carbonization of furfuryl alcohol mixed with ferrocene, and their electrochemical behavior in a redox reaction of Fe (CN) 6-3 was investigated mainly by cyclic voltammetric (CV) technique. The cyclic voltammogram changed by the introduction of iron from irreversible one to reversible one with the narrowing of the potential difference between anodic and cathodic peaks. The heterogeneous charge transfer constant ks of the composite electrode with the highest iron content, Fe (3)-PFA, was comparable with platinum electrode, and was the highest among various type of carbon electrodes including polycrystalline graphite, pitch coke, and carbonized poly (vinyl acetate). On the other hand, ks of the composite specimen with a smaller iron content, Fe (1)-PFA, was comparable with polycrystalline graphite. Acid washing of iron-carbon composites by concentrated HC1 could not remove all of the iron species, but the ks of Fe (3)-PFA was diminished by a factor of 4-5. The effect of iron was concluded to be promotion of carbonization and/or graphitization and to accelerate the heterogenious charge transfer at the surface of the electrode. The latter effect was observed only when greater amount of iron was introduced than that needed for promotion of carbonization and/or graphitization.