LOW-TEMPERATURE OPERATION OF SOLID ELECTROLYTE OXYGEN SENSORS USING PEROVSKITE-TYPE OXIDE ELECTRODES AND CATHODIC REACTION-KINETICS

The lowest limit of operation temperature for the oxide solid electrolyte oxygen sensors was affected by the electrode materials. The CeO2-based sensors with silver and cobalt-based perovskite-type oxide electrodes exhibited theoretical EMF's at lower temperatures than those with Pt electrodes. In particular, the sensor with La0.6Sr0.4Co0.98Ni0.02O3 attained theoretical EMF even at 200°C. The electrode materials operative at low temperatures tend to have low cathodic overpotential. From the kinetic analysis of the exchange current, the rate-determining step is expected to be the dissociative adsorption of oxygen molecules at high temperatures and the charge transfer process at low temperatures. © 1990, The Electrochemical Society, Inc. All rights reserved.