A Promising K-Doped Sr ₂ Fe _1.5 Mo _0.5 O _6-δ Nanofiber Oxygen Electrode Fabricated by Electrospinning as Proton-Conducting Solid Oxide Fuel Cells

Proton-conducting solid oxide fuel cells (PCFCs) represent a promising class of energy conversion technologies operating at intermediate to low temperatures. However, the development of efficient oxygen reduction reaction (ORR) catalysts remains a critical challenge for achieving practical performance in PCFCs. In this study, a series of K-doped Sr 2 Fe 1.5 Mo 0.5 O 6-δ (SFM) perovskites with triple-conducting characteristics, synthesized through electrospinning into a nanofiber architecture, are presented as high-performance oxygen electrode materials. The SK30FM electrode demonstrates exceptional electrochemical performance, exhibiting a low polarization resistance of 0.062 Ω cm 2 under wet air (3% H 2 O) at 750 °C, and delivering a peak power density of 645 mW cm –2 with decent short-term stability during fuel cell operation. These results highlight the significant potential of SFM-based perovskites as advanced oxygen electrodes for PCFCs, while also underscoring the advantages of electrospinning in fabricating nanostructured functional materials.