In-doped BaCoO3-δ perovskite as a novel cathode for solid oxide fuel cells

In-doped BaCoO 3–δ (BaCo 1–x In x O 3–δ , x = 0, 0.10, 0.15; denoted BC, BCI 10 , BCI 15 ) were synthesized via solid-state reaction. 15 mol% In 3+ doping stabilized the cubic phase and improved thermal expansion stability. Even 10 mol% In 3+ significantly enhanced oxygen reduction reaction activity, likely by favourably modifying the cobalt oxidation state within the cubic structure, thereby improving oxygen surface exchange. Symmetrical cells with BCI 10 and BCI 15 cathodes exhibited low area-specific resistances of 0.107 Ω cm 2 and 0.139 Ω cm 2 , respectively, at 650 °C. These results demonstrate that In 3+ doping produces highly promising cathodes for solid oxide fuel cells. • In 3+ doping dramatically alters the crystal structure of BaCoO 3-δ . • 15 mol% In 3+ doping stabilizes a cubic phase with electrolyte-compatible thermal expansion. • BCI 10 and BCI 15 exhibit excellent ORR activity from 600 to 800 °C. • BCI 15 emerges as a promising candidate for SOFC cathodes.