par Chevalet, Jean;Rouelle, F.;Gierst, Lucien ;Lambert, Jean-Paul
Référence Journal of electroanalytical chemistry, 39, 1, page (201-216)
Publication Publié, 1972-09
Article révisé par les pairs
Résumé : In the presence of surfactants such as quinoline which can form compact hydrophobic films, the inhibition of the polarographic reduction of oxygen selectively blocks the second electron transfer, and yields as main product the superoxide ion O2-. Under polarographic conditions, the reaction O2 + ε O2- nearly achieves reversibility. By comparing the data obtained by pulse polarography and reoxidation chronocoulometry, the standard potential of the system has been determined (Eo = - 0.270 V/NHE). From this value and the pK of the acid-base reactions between O2-, O2H and O2H2+, the full potential-pH diagram of the system O20-O2-1-O2-2 has been established. It shows that thermodynamic stability of O2- can only be expected in molten hydroxides-in agreement with fact. Electroreduction of O2- is a highly irreversible process. The non-additivity of the polarographic diffusion currents due to O2- generation and ferricyanide reduction, indicates that these two species react chemically in the diffusion layer. The behavior of electrodes other than mercury is briefly examined, in view of the possible role of O2- as first intermediate. © 1972.