The effect of Ca doping on high-surface-area Sr2Fe1.5Mo0.5O6-δ nanofibers as oxygen electrodes

Proton ceramic fuel cells (PCFCs) have emerged as promising next-generation energy conversion devices operating at intermediate temperatures (400-750 °C). The insufficient oxygen electrodes catalytic activity at intermediate temperatures largely restricts their practical application. Oxygen electrodes with sufficient oxygen reduction reaction (ORR) activity and operational durability are therefore needed. In this work, a series of Sr 2-x Ca x Fe 1.5 Mo 0.5 O 6-δ (SCaxFM, x = 0, 0.2, 0.3, 0.4) double perovskite nanofibers were synthesized via electrospinning and comprehensively evaluated as PCFC oxygen electrodes. Anode-supported single cells with the SCa30FM oxygen electrode deliver a peak power density of 652.17 mW cm −2 at 750 °C, approximately 84% higher than that of the SFM cell (353.59 mW cm −2 ), with operational stability over 100 h at 400 mA cm −2 and 650 °C. This work demonstrates that SCa30FM nanofibers represent a highly promising cobalt-free oxygen electrode material for intermediate-temperature PCFCs.