Calcium oxide as synergistic catalyst for oxygen reduction reaction on strontium-doped lanthanum ferrite for SOFC

作者：Xu, Wenming; Li, Chengyu; Hong, Tao^*; Pan, Xiang; Lu, Yingwei^*

来源：IONICS, 2024, 30(1): 421-431.

DOI：10.1007/s11581-023-05303-5

• Solid oxide fuel cell
• Cathode
• Calcium oxide
• Oxygen reduction reaction
• Strontium-doped lanthanum ferrite

CaO is demonstrated as a synergistic electro-catalyst for oxygen reduction reaction on strontium-doped lanthanum ferrite (La0.8Sr0.2FeO3-delta, LSF) cathodes for intermediate-temperature solid oxide fuel cells based on yttria-stabilized zirconia (YSZ) electrolytes. With 3.01 wt% CaO, the interfacial polarization resistance at 750 degrees C is reduced from 0.83 to 0.42 omega cm2 for LSF-SDC (samaria-doped ceria) composite electrodes on the YSZ electrolytes. With 3.2 wt% CaO, the peak power density at 800 degrees C is increased from 0.45 to 0.58 Wcm-2 for anode supported single cells consisting of Ni-YSZ anodes, YSZ electrolytes, and LSF-SDC cathodes. The CaO particles can greatly enhance the kinetics of oxygen reduction reaction on LSF such as improving the oxygen surface exchange coefficient at 750 degrees C from 1.9 x 10-5 to 54x10-5 cm s-1 as demonstrated by the electrochemical conductivity relaxation measurement. Specifically, CaO particles infiltrated to the LSF electrodes reduce the interfacial polarization resistance associated with the low-frequency response, which is often attributed to the surface reaction steps of the cathode reaction.