Self-Regenerating Co-Fe Nanoparticles on Perovskite Oxides as a Hydrocarbon Fuel Oxidation Catalyst in Solid Oxide Fuel Cells

Metal nanoparticles exsolved from perovskite oxides have created great interest as anode materials in solid oxide fuel cells (SOFC) due to their high catalytic activity and regenerative capability. However, the self-regeneration process generally occurs at relatively high temperatures (>800 degrees C), which might limit their practical application. Here, we present a perovskite anode material, La0.3Sr0.7Cr0.3Fe0.6Co0.1O3_delta, which allows Co-Fe nanoparticles exsolved on the oxide surface at intermediate operation temperatures (700 degrees C). The phase stability of the perovskite oxide and the reversibility of the exsolved alloy were carefully examined by the phase characterization and the nanoparticle morphology observation during the redox process. The electrochemical performance was evaluated by an electrolyte-supported single cell with hydrogen and propane fuels. The Co-Fe nanocatalysts enhance the maximum power density of the La0.3Sr0.7Cr0.3Fe0.6Co0.1O3-delta- Gd0.2Ce0.8O1.9 (GDC) composite anode more than 75% in comparison to that of the cobalt-free La0.3Sr0.7Cr0.3Fe0.6Co0.1O3-delta-GDC composite anode with hydrogen. The self-regeneratable anode drives off carbon deposition with hydrocarbon fuels and facilitates catalytic reactivation by the redox cycles without requiring a higher-temperature process. Additionally, the dispersed Co-Fe nanoparticles with a random distribution and slow particle growth rate ensure long-term performance. The single-cell SOFC evaluation demonstrates that La0.3Sr0.7Cr0.3Fe0.6Co0.1O3-delta with Co-Fe nanoparticles exhibits acceptable H2S tolerance, excellent redox reversibility, and stable long-term performance for more than 200 h with H-2 and over 800 h with propane at 700 degrees C.