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

Abstract Layered perovskite related oxides, LnBaCo₂O_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 NdBaCo₂O_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−xBi_xO_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 cm² 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−xBi_xO_5+δ cathode is much more robust against CO₂ than that of NBC cathode. This work indicates that bismuth doping in the B‐site of LnBaCo₂O_5+δ may be a highly attractive strategy for the future development of cathode materials.