Electrocatalysis of Oxygen Using Water Soluble Metal Porphyrins and Chemically Modified Porphyrin Electrodes.
Final rept. 1 Sep 78-31 Mar 83,
OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS
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Primary effort was devoted to the study of oxygen reduction using wateroluble iron and cobalt porphyrins, namely, iron and cobalt tetrakis N-methyl-4-pyridylporphyrin. These porphyrins with the metal in the 3 oxidation state can be electrochemically reduced to the divalent state which can then reacted with oxygen. In the case of the iron containing porphyrin, oxygen was reduced at a bimolecular rate of ca. 1 x 10 to the minus 7th power 1ms to hydrogen perioxide which was then reduced rapidly to water. A mechanistic scheme was postulated for the reduction and using experimentally determined parameters, current-potential curves were simulated. Good agreement between the experimental and computer calculated current-potential curves supported the proposed scheme. Cross-correlation between optical, electrochemical and magnetic circular dichroism results have provided axial ligation, dimerization and spin state information of the ferric and ferrous tetrakis n-methyl-4-pyridylporphyrins. Glassy or graphitic carbon electrodes were rendered catalytic by the incorporation of iron porphyrin derivatives infinity e.g. iron tetra-o-amino-phenylporphyrin and iron tetra-N2-hydroxyethylpyridylporphyrin summation in thin polymeric films adhering to the carbon. The extent of oxygen reduction to hydrogen peroxide and water depended on the amount of iron porphyin.
- Inorganic Chemistry
- Physical Chemistry