Hydrogen Oxidation at the Nickel and Platinum Electrodes on Yttria‐Tetragonal Zirconia Electrolyte

H{sub 2} oxidation has been studied for Pt and Ni electrodes for different H{sub 2}/H{sub 2}O ratios at 1,000 C in solid oxide fuel cells using yttria-tetragonal zirconia electrolyte by galvanostatic current interruption and electrochemical impedance spectroscopy. The results clearly indicate that the mechanism and kinetics of the H{sub 2} oxidation reaction are strongly dependent on the catalytic activities of electrode materials, electronic conductivity of the electrolyte surface, and the water content in H{sub 2} gas. The effect of water vapor in H{sub 2} gas on the reaction kinetics is very much dependent on the electrode materials and is related to the partial pressure of oxygen. A reaction mechanism with two rate-limiting steps has been proposed and discussed.