Study of the oxygen electrode reaction using mixed conducting oxide surface layers. Part II: Small signal analysis

Abstract

The oxygen gas electrode has been studied for a number of mixed conducting oxide surface layers on top of Gd 2Zr 2O 7 (TGZO) solid electrolytes. In part II of this paper we present the results of frequency dispersion measurements for the electrode reaction, supplying additional information to the results of current-overvoltage experiments presented in part I. For both kinds of experiments the same trends were observed for the electrode polarization. Best results are obtained for a surface layer of TGZO, while p-type mixed conducting oxides give less decreased values of the electrode polarization. High electrode capacitances were found in the case of mixed conducting surface layers (about 700 F/m 2). The electrode reactions follow a Butler-Volmer type of equation. Most probably a diffusion process is rate controlling the overall charge transfer process.