High‐Performance Electrode for Medium‐Temperature Operating Solid Oxide Fuel Cells: Polarization Property of Ceria‐Based Anode with Highly Dispersed Ruthenium Catalysts in Gas

Polarization properties of catalyzed anode, which we developed for medium‐temperature operating solid oxide fuel cells, were examined in a synthetic gas containing and . The overpotential was greatly decreased by loading only a small amount of Ru microcrystals onto the mixed conducting oxide, samaria‐doped ceria (SDC), anode layer in both synthetic gas and wet hydrogen atmospheres. It was found that the Ru‐SDC anode exhibited the highest electrocatalytic activities at an optimum oxygen partial pressure in the fuel gas due to high conductivities of both electrons and oxide ions in the SDC. The maximum current density on the Ru‐SDC anode exceeded 1 A/cm² at all the operating temperatures between 800 and 1000°C at the potential of −0.9 V vs. air reference electrode, when 0.1 mg/cm² of Ru microcatalysts were loaded on the SDC surface and the appropriate fuel gas was used.