Influence of the coexisting gases on the electrochemical reaction rates between 873 and 1173 K in a CH4-H2O/Pt/YSZ system

The rates of electrochemical reactions were clarified in a CH4-H2O system a t the interface of a porous Pt electrode/Y2O3-stabilized ZrO2 (YSZ) electro lyte between 873 and 1173 K to elucidate the kinetics of the anode reaction of solid oxide fuel cells (SOFCs). The dominant electrochemical reaction w as found to be the redox process of H-2/H2O, where H-2, C, CO, and CO2 were formed without a current by the chemical reactions in a CH4-H2O system. Th e partial electrochemical reaction rates of H-2, CO, C, and CH4 were determ ined. The rate of the electrochemical reaction of CO/CO2 in a CH4-H2O syste m is larger than that in a CO-CO2 system under anodic polarization at 873 a nd 973 K. This means both the efficiency and the rate of the utilization of fuels on SOFCs are increased. (C) 2000 Elsevier Science B.V. All rights re served.