Anchored nanocatalysts enable efficient oxygen reduction in barium cobaltite cathodes

Solid oxide fuel cells (SOFCs) are hindered by sluggish oxygen reduction reaction (ORR) kinetics at the cathode. Ex-solution, which generates socketed nanoparticles from the perovskite lattice, offers a promising strategy to overcome this limitation but has rarely been applied to cathodes. In this work, BaCo_0.8Ta_0.2O_3-δ (BCT) was doped with Ag, Cu, and Ni to induce ex-solution under controlled reducing conditions. Structural and microscopic analyses confirmed the formation of socketed nanoparticles on the perovskite surface. Electrochemical measurements showed that ex-solved cathodes exhibited reduced polarization resistance (R_p) compared to their non ex-solved counterparts, with ex-solved BCT-Ag (eBCT-Ag) achieving the lowest R_p (0.0210 Ω cm² at 650 °C, ∼49% reduction). A single-cell test with eBCT-Ag delivered a maximum power density of ∼0.68 W cm^-2 at 650 °C. These results demonstrate the successful application of ex-solution to SOFC cathodes, providing an effective pathway for high-performance cathode design.