Catalysis of dioxygen reduction at glassy carbon and carbon fibre electrodes coated with poly-cobalt(O-aminophenyl)porphyrin film

Abstract

Electrooxidation of tetra(O-aminophenyl)porphyrin (H 2Co-TAPP)) in acetonitrile results in the formation of a polymer film on glassy carbon (GC) and carbon fibre (CF) surfaces. These films can be made electrocatalytically active toward dioxygen by metallization with Co(II). The film coverage of electroactive cobolt porphyrin are 1.1 ∼ 1.4 × 10 −9 mol cm −2. Dct determined by chronoamperometry are 8.4 × 10 −12 and 5.5 × 10 −12 cm −2 s −1 in 0.05 M H 2SO 4 and 0.05 M phosphate buffer respectively. Cyclic voltammetry, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) have been used to characterize these films. The polymer film electrodes are stable in organic and aqueous solution under various acidic and basic conditions and catalyze dioxygen reduction to produce hydrogen peroxide at + 0.15–+0.20V ( vs Ag/AgCl. sat. KCl) in acidic media. The activity of such polymer film electrodes decreases only by 10% when repetitively cycled between the potentials of +0.6 to −0.6 V vs Ag/AgCl. sat. KCl) for 100 scan or more at a scan rate of 100 mV s −1.