Electrocatalytic reactions by an iron porphyrin/polypyrrole modified electrode monitored by electrochemical quartz crystal microbalance

Electropolymerization of pyrrole in aqueous solution is monitored by electr ochemical quartz crystal microbalance (EQCM) during potential scan. The fil m formation process on the electrode is reflected by the frequency decrease for the quartz oscillator as a function of time. The film growth rate is g reatly enhanced in the presence of iron(III) meso-tetrakis(3-sulfonatomesit yl)porphyrin, which carries 3- of charge. The metalloporphyrin is trapped a nd remains intact in the polypyrrole films. The ion transport property thro ugh the iron porphyrin/polypyrrole film is the reverse of that for pure pol ypyrrole. Electroreduction of dioxygen and electrooxidation of alkenes are parallel to those in the solution state.