Advanced oxygen reduction kinetics and CO2 tolerance of Fe-based double-perovskite cathode electrocatalyst for solid oxide fuel cells

Developing highly active and stable cobalt-free cathode materials is crucial for advancing solid oxide fuel cells (SOFCs). In this work, we designed and synthesized a Ta-doped double-perovskite material NdBaFe 1.9 Ta 0.1 O 5+ δ (NBFT) as candidate cathode electrocatalyst for SOFCs. The phase structure, electrocatalytic performance, and oxygen reduction reaction (ORR) kinetics of the NBFT cathode were systematically investigated. The NBFT electrocatalyst exhibits excellent ORR performance, achieving a low polarization resistance of 0.21 Ω cm 2 and a high peak power density of 701 mW cm −2 in anode-supported single cells at 700 °C. The density functional theory (DFT) calculations further verify that tantalum doping reduces charge transfer energy and enhances oxygen adsorption energy, thereby facilitating oxygen ion migration and surface oxygen exchange. This work develops a viable strategy to engineer high-performance cobalt-free cathode electrocatalyst. Meanwhile, the underlying mechanism by which high-valence doping regulates and optimizes the electrocatalytic activity of cathode is further clarified.