Oxygen Reduction on Poly(4-vinylpyridine)-Modified Ordinary Pyrolytic GraphiteElectrodes with Adsorbed Cobalt Tetra-sulphonated Phthalocyanine in Acid Solutions

摘要

Poly(4-vinylpyridine) (PVP) has been used to modify ordinary pyrolytic graphite(OPG) electrodes with adsorbed cobalt tetra-sulphonated phthalocyanine (CoTsPc) in acid solutions. These modified electrodes were prepared in different manners and characterized by cyclic voltammetry. Their electro-catalytic activity for oxygen reduction and stability in 0.05 m H2SO4 solutions was examined at room temperature. The OPG/CoTsPc/PVP modified electrodes were found to be more active for oxygen reduction in 0.05m H2SO4 solutions as compared to the electrode with adsorbed CoTsPc on OPG without PVP. The increase in activity is due to the formation of an adduct between PVP and CoTsPc. U.v.-visible and FTIR studies provide evidence for such adduct formation. Over a 10 h period the activity of the OPG/CoTsPc/PVP system was essentially constant while that of OPG/CoTsPc without polymer decreased by a substantial amount (about 37%). The PVP layer inhibits the diffusion of the CoTsPc and/or Co out of the complex into the solution phase.