Electro-reduction of Oxygen to Water Mediated by Stable Glassy Carbon Electrodes Modified by Co(II)-porphyrins with Voluminous Meso-Substituent

Abstract

Glassy carbon electrodes were modified by physisorption of two different Co(II)-porphyrins, specifically designed and synthesized to study the effect of the substitution pattern (and the resulting steric hindrance) on the electrocatalytic behavior for a characteristic inner-sphere reaction such as the reduction of oxygen. In spite of the change in morphology caused by a change in the relative positions of the meso substituents, they showed practically the same behavior toward the electro-reduction of O-2. In both cases, water was obtained as the main product. The modified electrodes were also active toward the electro-reduction of hydrogen peroxide. Both electrodes were found stable for more than a month upon exposure to air and the current for the electro-reduction remained practically the same.