Electrochemical investigation of a propane-fed solid oxide fuel cell based on a composite Ni-perovskite anode catalyst

A composite Ni-perovskite anode was investigated for operation in dry propane-fed intermediate temperature solid oxide fuel cells (IT-SOFC). A La0.6Sr0.4Fe0.8Co0.2O3 (LSFCO) perovskite, characterized by mixed electronic-ionic conductivity, was used to support a highly dispersed Ni-phase. However, the catalyst structure was modified during SOFC operation. X-ray diffraction analysis of the electrocatalyst showed that, after operation, Ni was mainly present as La2NiO4; whereas, the LSFCO structure was partially modified into a lanthanum-depleted SrFe1xCoxO3y (SFCO) perovskite structure. These results were corroborated by X-ray photoelectron spectroscopy (XPS). Transmission electron microscopy (TEM) analysis showed the presence of a suitable dispersion of a nanosized Ni-phase and a strong interaction of Ni-enriched particles with the perovskite substrate. High reaction rates for the propane reaction were achieved with this electrocatalyst while minimizing carbon deposition. Power densities of about 300 mWcm2 for dry propane oxidation were obtained at 800 °C in the presence of a thick gadolinia doped ceria electrolyte. Fuel cell time-tests indicated promising electrochemical stability.