Direct bioelectrocatalytic reduction of hydrogen peroxide at chloroperoxidase modified graphite electrode

Abstract

The electroreduction of hydrogen peroxide was studied at a chloroperoxidase-modified graphite electrode. The reduction of H₂O₂ starts at more negative potentials than 0.45 V versus SCE at pH 7.0. The steady-state reduction currents are greater at acidic pH values, and in the presence of chloride ions in solution. The apparent Michaelis–Menten constant and sensitivity were evaluated to be equal to 105 µmol l^–1 and 1.3 mA l mol^–1 for the electrode responses to the H₂O₂ in 0.1 mol l^–1 phosphate buffer solution free of chloride ions. On the basis of these results direct electron transfer is postulated between the active site of chloroperoxidase and the graphite electrode.