Ni-Fe nanoparticles are observed to exsolve from Ni-substituted Sr 0.95 (Ti 0.3 Fe 0.63 Ni 0.07 )O 3Àd anode. The exsolved nanoparticles act to enhance hydrogen dissociative adsorption, yielding much lower anode polarization resistance and higher cell performance, especially under low pH 2 and temperatures, which is comparable with the current Ni-based cermets.

Solid oxide fuel cells with (La,Sr)(Ga,Mg)O3 electrolytes and Sr(Ti0.3Fe0.7)O3 anodes and cathodes yield a power density of 0.6 W/cm2 at 0.7 V at 800°C in air and humidified hydrogen. The polarization resistance values are 0.085 Ω·cm2 for the cathodes and 0.13 Ω·cm2 for the anodes. The cell current-voltage characteristics and the anode resistance dependence on hydrogen partial pressure (pH2) both indicate that adsorption limits the hydrogen oxidation process. A model is developed where dissociative hydrogen adsorption becomes an increasingly important rate-limiting step, relative to charge transfer, as temperature and pH2 decrease. The model fits the data well for cell voltages >0.5 V, deviations at lower voltages are tentatively explained by an increase in anode oxygen content. The model also fits the electrochemical characteristics of cells with (La,Sr)(Cr,Fe)O3 anodes and previously-reported data on other oxide anodes.

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