Cn. Shi et Fc. Anson, POTENTIAL-DEPENDENCE OF THE REDUCTION OF DIOXYGEN AS CATALYZED BY TETRARUTHENATED COBALT TETRAPYRIDYLPORPHYRIN, Electrochimica acta, 39(11-12), 1994, pp. 1613-1619
The electroreduction of O-2 at rotated graphite disk electrodes coated
with cobalt tetra-pyridylporphyrin was examined at potentials on the
rising portion of the current-potential curve, both before and after f
our Ru(NH3)(5)(2+) groups were co-ordinated to the pendant pyridine li
gands. The unruthenated porphyrin provides a two-electron reduction of
O-2 with a Tafel slope near 120 mV per decade. The ruthenated porphyr
in provides a primarily four-electron reduction with a Tafel slope nea
r 90mV per decade. Some mechanistic implications of the results are di
scussed including the likelihood that an array of partially reduced an
d partially oxidized ruthenated porphyrins participates in the catalys
is of the reduction of O-2 via a set of parallel reactions.