VOLTAMMETRIC STUDIES OF ELECTROCHEMICAL PROCESSES AT THE INTERFACE PT-VERTICAL-BAR-YSZ BETWEEN 300-DEGREES-C AND 600-DEGREES-C

Electrochemical processes occurring at the interface platinum\yttria-s tabilized zirconia were investigated by cyclic voltammetry and potenti ostatic current-potential curves, taken under steady-state conditions, in different mixtures of oxygen and nitrogen at temperatures between 300 and 600 degrees C. Point or paste electrodes were used. The exchan ge current of the rate-determining step of the oxygen reduction become s very small below 500 degrees C. Therefore, the equilibrium of the ox ygen electrode is no longer established. A layer of chemisorbed oxygen atoms is formed anodically on the contact surface of the point electr ode, not by the dissociation of O-2 at the three-phase boundary. The s hape of the cyclic voltammograms is discussed. (C) 1997 Elsevier Scien ce S.A.