Abstract
The electrochemical properties of mixed conducing ceramic–ceramic composites for proton conducting fuel cells have been investigated. Different ratios of Pr~0.58~Sr~0.4~Fe~0.8~Co~0.2~O~3–δ~–BaCe~0.9~Yb~0.1~O~3–δ~ composites have been tested as cathodes in symmetrical cells based on BaCe~0.9~Y~0.1~O~3–δ~ dense electrolytes. Impedance measurements have been carried out in the temperature range of 600–800 °C under wet (2.5%) air. Different dilutions on both oxygen partial pressure and water content have been performed as a function of the temperature in order to characterise the processes (surface reaction and charge transport) occurring at the composite electrode under oxidising conditions. The variation of the impedance spectra after replacing protonated water by heavy water has been studied in order to understand the role of the proton transport in the overall composite cathode operation. Additional four‐point DC‐conductivity measurements have been done under different atmospheres comprising different oxygen partial pressures and H~2~O/D~2~O saturation for composites and single materials.