Rotating-Ring-Disc Analysis of Iron Tetra(N-methylpyridyl)Porphyrin in Electrocatalysis of Oxygen

When cyclic voltammetry and the rotating ring-disc electrode (RRDE) were used, the water soluble Iron tetra( N-methylpyrldyl)porphyrin (FeTMPyP) was found to catalyze O2 electroreduction by ca. 400 mV and produce H2O2, at a yield of 95 %, as the initial product. Using the RRDE method, the rate of removal of Fe(II)TMPyP by O2 was estimated to be in the 107-108 M-1 s-1 region. A mechanism involving an “iron(III)-superoxide ion” Intermediate seems to be consistent with the above experimental results and with other data reported in the literature.