Enhancing Oxygen Reduction Activity and CO₂ Tolerance by a Bismuth Doping Strategy for Solid Oxide Fuel Cell Cathodes

Layered perovskite related oxides, LnBaCo 2 O 5+ δ (Ln = rare‐earth element) are potential ceramic cathodes for intermediate temperature solid oxide fuel cells. Herein, a simple way to tune the performance of NdBaCo 2 O 5+ δ (NBC) perovskite as a cathode by doping the Co‐site with bismuth cation is reported. Compared with the parent oxide, the obtained stabilized double perovskites NdBaCo 2− x Bi x O 5+ δ ( x = 0.1 and 0.2) show a much improved electrocatalytic activity, achieving area‐specific resistance of 0.268, 0.107 and 0.152 Ω cm 2 at 700 °C in air for NBC, x = 0.1, and 0.2, respectively. Density functional theory results demonstrate that bismuth doping effectively reduces the formation energy of oxygen vacancies. Moreover, the bismuth doping of NdBaCo 2− x Bi x O 5+ δ cathode is much more robust against CO 2 than that of NBC cathode. This work indicates that bismuth doping in the B‐site of LnBaCo 2 O 5+ δ may be a highly attractive strategy for the future development of cathode materials.