Electrocatalysis of the reduction of O_2 to H_2O by tetraruthenated cobalt meso-tetrakis(4-pyridyl)porphyrin adsorbed on graphite electrodes

Coordination of Ru(NH_3)_5 groups to the four pyridine sites in cobalt meso-tetrakis(4-pyridyl)porphyrin adsorbed on pyrolytic graphite electrodes produces the tetraruthenated complex which acts as a catalyst for the four-electron reduction of O_2 to H_2O. The adsorbed catalyst, prepared by this heterogeneous coordination reaction, yields higher catalytic reduction rates than those obtained previously when the same catalyst was prepared within Nafion coatings on electrodes. The coordination chemistry used in the preparation of the adsorbed catalyst and its behavior as an electrocatalyst are described.