The electro-oxidation of cobalt (H) octaethylporphyrin adsorbed on graphite
electrodes, Co-II(OEP)(ads') to Co-III(OEP)(ads)(+), in the presence of aq
ueous solutions of CO leads to catalytic oxidation of CO to CO2. No such ad
oxidation occurs with Co-II(OEP) and CO dissolved in nonaqueous solvents.
Coordination of the CO to Co-III(OEP)(+) is the first step in the catalytic
mechanism. Nucleophilic attack on the coordinated CO by H2O is the probabl
e rate-limiting step in the catalytic oxidation. A pseudo first-order rate
constant of 0.3 s(-1) was estimated for this reaction.