Enhanced reducibility of ceria–YSZ composites in solid oxide electrodes

Abstract

Composites prepared by infiltration of 50- wt% ceria into porous YSZ were investigated for use as H2–H2O electrodes for solid oxide electrolyzers (SOE) or fuel cells (SOFC). Cells prepared from these composites showed excellent performance, with SOFC power densities as high as 1.1 W cm−2 at 1073 K. Further investigations into the electrodes showed that they had significantly higher conductivities than would be expect for a material that was only 35 vol% ceria, as high as 0.25 S cm−1 at 1073 in 3% H2O–97% H2 mixtures. An investigation into the thermodynamic redox properties of the composite using coulometric titration at 973 K indicated that the ceria in the composite remained significantly reduced to higher P(O2) compared to pure ceria, probably due to interactions at the ceria–YSZ interface.