A NEW INDICATOR ELECTRODE FOR OXYGEN SENSORS

The electrochemical reduction of O-2, was studied at Ni-Cu alloy electrodes in aqueous alkaline solution (0.1-6.0 M KOH) and in unbuffered neutral solution (0.1-2.0 M KCl) using the rotating disk electrode technique. Voltammetric measurements showed that the overall O-2 reduction process at the electrodes containing 70-90% Cu is transport-limited at cathodic potentials, and that they can be used as indicator electrodes for galvanic-type oxygen sensors. An industrially produced Ni-Cu alloy ''melhior'', which contains similar to 30% Ni, was also studied, and this alloy proved to be an excellent O-2 reduction catalyst. Melhior electrodes were utilized as indicator electrodes for oxygen sensors, and showed high output current stability and a long lifetime (exceeding one year).