NdBaFe_2–xCo_xO_5+δ Double Perovskites with Exsolved Co–Fe Alloy Nanoparticles as Highly Efficient and Stable Anodes for Direct Hydrocarbon Solid Oxide Fuel Cells

Exsolution of transition metals in perovskites is a potential way to improve the catalytic activity of fuel cell anode materials. In this work, the double-perovskite anodes PR-NdBaFe_2–xCo_xO_5+δ (x = 0.1, 0.2; PR-NBFC10, PR-NBFC20) with the exsolved Co_0.72Fe_0.28 metal alloy nanoparticles were obtained by heat treatment in 5% H₂/Ar post-reduction at 850 °C. The exsolved Co–Fe alloy nanoparticle catalyst uniformly distributed on the surface of the cobalt-doped PR-NBFC10 and PR-NBFC20 ceramic anodes facilitates the catalytic activity compared with the undoped PR-NdBaFe_2–xCo_xO_5+δ (x = 0; PR-NBFC0) anode. The maximum power density of single cells with PR-NBFC0, PR-NBFC10, and PR-NBFC20 anodes supported by a 200 μm thick La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ electrolyte at 850 °C in wet H₂ reached 842, 1110, and 1247 mW cm^–2, respectively. In addition, PR-NBFC0, PR-NBFC10, and PR-NBFC20 exhibit relatively stable output power in a wet CH₄ fuel within 100 h of operation. Since the exsolved Co–Fe alloy nanoparticles have an embedded structure, they exhibit impressive anticoking properties, which greatly expand their application. The PR-NBFC double perovskite containing Co–Fe alloy nanoparticles offers possibilities for finding promising high-catalytic-activity and high-stability anodes for solid oxide fuel cells.