THE ELECTROCHEMICAL OXIDATION OF CARBON-MONOXIDE ON A PLATINUM SOLID PROTONIC CONDUCTOR INTERFACE

The detection of carbon monoxide in air by potentiometric or amperometric solid state sensors employing protonic conductor/platinum interfaces has been reported recently. The aim of the present investigation is the study on these interfaces of the electrochemical oxidation of CO which shows different aspects from those reported for aqueous solutions. The behaviour of such an electrochemical process studied using typical protonic conductors is controlled by the formation of a precursor that reacts rapidly with CO. This species, which is probably the radical OH(ad), may be formed (depending on the applied potential) either by oxidation of water or by reduction of oxygen. The latter electrochemical reaction is responsible for the mixed potential that allows CO to be detected potentiometrically.