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

In-doped BaCoO_3–δ (BaCo_1–xIn_xO_3–δ, x = 0, 0.10, 0.15; denoted BC, BCI₁₀, BCI₁₅) were synthesized via solid-state reaction. 15 mol% In³⁺ doping stabilized the cubic phase and improved thermal expansion stability. Even 10 mol% In³⁺ 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 BCI₁₀ and BCI₁₅ cathodes exhibited low area-specific resistances of 0.107 Ω cm² and 0.139 Ω cm², respectively, at 650 °C. These results demonstrate that In³⁺ doping produces highly promising cathodes for solid oxide fuel cells.