Oxygen reduction at the Ag|Gd_(0.2)Ce_(0.8)O_(1.9) interface studied by electrochemical impedance spectroscopy and cyclic voltammetry at the silver point electrode

摘要

Reduction of oxygen at the silver point electrode|Gd_(0.2)Ce_(0.8)O_(1.9) interface was studied by cyclic voltammetry and electrochemical impedance spectroscopy. Measurements were performed in the 500-700 ℃ temperature range, at the atmospheric pressure, in oxygen and in argon/oxygen atmospheres. The results of the experiments are consistent with the mechanism in which the oxygen reduction reaction proceeds through the non-electrochemical adsorption/dissociation step and a two-electron two-step electrochemical reaction with the transfer of the first electron as a rate-determining step. Slow diffusion of oxygen is confirmed by both electrochemical impedance spectroscopy and cyclic voltammetry techniques. New equivalent electrical circuit for the investigated interface is proposed.