Accession Number : ADA136062

Title :   Electrocatalysis of Oxygen Using Water Soluble Metal Porphyrins and Chemically Modified Porphyrin Electrodes.

Descriptive Note : Final rept. 1 Sep 78-31 Mar 83,


Personal Author(s) : Kuwana,T

PDF Url : ADA136062

Report Date : 01 Nov 1983

Pagination or Media Count : 16

Abstract : Primary effort was devoted to the study of oxygen reduction using wateroluble iron and cobalt porphyrins, namely, iron and cobalt tetrakis (N-methyl-4-pyridyl)porphyrin. 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 1/m/s 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-pyridyl)porphyrins. Glassy or graphitic carbon electrodes were rendered catalytic by the incorporation of iron porphyrin derivatives infinity e.g. iron tetra-(o-amino-phenyl)porphyrin and iron tetra-(N(2-hydroxyethyl)pyridyl)porphyrin 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.

Descriptors :   *Oxygen, *Reduction(Chemistry), *Electrocatalysts, Water soluble materials, Electrochemistry, Porphyrins, Iron, Platinum, Carbon, Electrodes, Surface reactions

Subject Categories : Inorganic Chemistry
      Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE