Abstract
A study has been conducted on the effects of electrode materials and electrolyte stabilizers on the kinetics of the oxygen cathodic reaction at the oxygen electrode/stabilized Bi 2O 3 electrolyte interface in the temperature range of 450-700°C under dry N 2+20% O 2 gas mixture. The La l-xM xCoO 3 electrodes prepared by the thermal decomposition method employing the ultrasonic technique and the Ag electrodes by the rf magnetron sputtering method were used as the oxygen electrodes. The electrode/electrolyte interface behaviour was investigated by means of dc and ac measurements. The electrolyte polarization or iR drop could be distinguished from the electrode polarization using an ac method and a current interruption method with the aid of a reference electrode. The electrode process is significantly influenced by the nature of the electrode/electrolyte interface. The dc and ac polarization properties for the system of (Bi 2O 3) 0.77(Y 2O 3) 0.23/La 0.5Sr 0.5CoO 3 electrode prepared by the thermal decomposition method using the ultrasonic technique were more favorable than that of the other electrode/electrolyte systems. The impedance results for the La 0.5Sr 0.5CoO 3 electrode system were different from those for the Ag-sputtered electrode system. It can be considered that the differences are due to the interaction condition between an electrode and an electrolyte, ie the electrochemical matching condition. The reaction mechanisms were also investigated. In the La 0.5Sr 0.5CoO 3 electrode system, the diffusion process of O − ad and/or V + + 0 along and/or through the interface, respectively, and in the Ag electrode system the O − 2 migration process along the interface play an important role in determining the reaction kinetics.
Published Version
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