Electrocatalysis at Redox Polymer Electrodes with Separation of the Catalytic and Charge Propagation Roles. Reduction of O2 to H2O2 as Catalyzed by Cobalt(II) Tetrakis(4-N-methylpyridyl)porphyrin

Article abstract of DOI:10.1021/ja00298a008

The kinetics of the reduction of O2 by Ru(NH3)6(2+) as catalyzed by cobalt(II) tetrakis(4-N-methylpyridyl)porphyrin are described both in homogeneous solution and when the reactants are confined to Nafion coatings on graphite electrodes.The catalytic mechanism is delineated and the factors that can control the total reduction currents at Nafion-coated electrodes are specified.A kinetic zone diagram for analyzing the behavior of catalyst-mediator-substrate systems at polymer-coated electrodes is presented and utilized in identifying the current-limiting processes.Good agreement is demonstrated between calculated and measured reduction currents at rotating disk electrodes.The experimental conditions that will yield the optimum performance of coated electrodes are discussed, and a relationship is derived for the optimal coating thickness.