Abstract
The electro-reduction of oxygen is effectively catalysed by metal chelates of the N4-type. The mechanism of this process has been found to be a modified ‘redox catalysis’. O2 molecules and the products of their reaction, at least up to H2O2, remain strongly co-ordinated to the central metal ion of the chelates XMeII. The potential-determining step, which regenerates the reduced form, is the following: (XMeIII...O2H)++H++ 2e→XMeII+H2O2.
H2O2 is further decomposed via the catalase action of the electrocatalyst. The mechanism is confirmed by experimental results with iron phthalocyanine (FePc) and cobalt-dibenzotetraazaannulene (CoTAA) as a O2-slurry electrode at various O2 pressures. The latter shows anodic reaction-limited currents, which seem to involve also oxygen-containing intermediates. The implication of the presented mechanism in regard to other electrochemical processes is discussed briefly.
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Beck, F. The redox mechanism of the chelate-catalysed oxygen cathode. J Appl Electrochem 7, 239–245 (1977). https://doi.org/10.1007/BF00618991
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DOI: https://doi.org/10.1007/BF00618991