HIGH-PERFORMANCE ELECTRODE FOR MEDIUM-TEMPERATURE OPERATING SOLID OXIDE FUEL-CELLS - POLARIZATION PROPERTY OF CERIA-BASED ANODE WITH HIGHLYDISPERSED RUTHENIUM CATALYSTS IN (H-2+CO2+H2O) GAS

Polarization properties of catalyzed anode, which we developed for med ium-temperature operating solid oxide fuel cells, were examined in a s ynthetic gas containing H-2, CO2, and H2O. The overpotential was great ly decreased by loading only a small amount of Ru microcrystals onto t he mixed conducting oxide, samaria-doped ceria (SDC), anode layer in b oth synthetic gas and wet hydrogen atmospheres. It was found that the Ru-SDC anode exhibited the highest electrocatalytic activities at an o ptimum oxygen partial pressure in the fuel gas due to high conductivit ies of both electrons and oxide ions in the SDC. The maximum current d ensity on the Ru-SDC anode exceeded 1 A/cm(2) at all the operating tem peratures between 800 and 1000 degrees C at the potential of -0.9 V vs . air reference electrode, when 0.1 mg/cm(2) of Ru micro-catalysts wer e loaded on the SDC surface and the appropriate fuel gas was used.