Design principle and assessing the correlations in Sb-doped Ba_0.5Sr_0.5FeO_3–δ perovskite oxide for enhanced oxygen reduction catalytic performance

Lack of fundamental understanding of the oxygen reduction reaction (ORR) hampers the development of effective metal oxide catalysts and advance low-temperature solid oxide fuel cells (LT-SOFCs). In this study, we report Ba_0.5Sr_0.5Fe_1–xSb_xO_3–δ (BSFSb, x = 0, 0.05, and 0.1) cathodes designed from both theoretical and experimental aspects to study a good relationship between a material property and enhanced ORR activity. The BSFSb cathode exhibits a very low area-specific resistance (ASR) of 0.20 Ω cm² and excellent power output of 738 mW cm⁻² using the Sm_0.2Ce_0.8O₂ (SDC) electrolyte at 550 °C. The Sb ions doping significantly enhances electrical conductivity and reduces its ORR activation energy. First-principles calculations screen the potential of designed perovskite by showing very low vacancy formation energy and shift in O-p and Fe3-d band centers near to fermi level by replacing Fe with Sb ions. Correspondingly, wide range coverage of distributed orbitals at the fermi level in BSFSb cathode promotes charge transfer with lower energy barrier. These results demonstrate that this design can impact the development of highly functional ORR electrocatalysts for LT-SOFCs and other electrocatalyst applications.