Pd catalyzed Sr0.92Y0.08TiO3−δ/Sm0.2Ce0.8O2-δ anodes in solid oxide fuel cells

The effects of palladium (Pd) on Sm0.2Ce0.8O2−δ coated Sr0.92Y0.08TiO3−δ (SDC/SYT) anodes were investigated for H2 and CH4 fuels. The electrochemical oxidations of both H2 and CH4 were accelerated by Pd impregnation. Moreover, Pd in the SDC/SYT (Pd-SDC/SYT) anode improved the cell performance by a factor of approximately 2 for H2 and 1.5 for CH4. The open circuit voltage (OCV) of the wet CH4 fuel increased with increasing temperature for both the SDC/SYT anode cell and Pd-SDC/SYT anode cell, which differs from that of the H2 fuel. Notably, the OCV values of the Pd-SDC/SYT anode cell using wet CH4 were much higher than those using wet H2. We observed differing potentials for the reformed gases after the out-of-cell catalyst experiment, and the CH4 fuel with the Pd-SDC catalyst layer agreed well with the OCVs of the Pd-SDC/SYT anode cell with directly introduced wet CH4 fuel. These results indicate the OCVs were higher than the theoretical values based on electrochemical hydrogen oxidation at increased temperatures in the Pd-SDC/SYT anode cell because of the lower water partial pressure caused by the increased steam reformation activity of Pd.