Structures and Properties of LaFe(0.8)Cu(0.2)O(3−δ) and BaFe(0.8)Cu(0.2)O(3−δ) as Cobalt‐Free Perovskite‐Type Cathode Materials for the Oxygen Reduction Reaction

Perovskite oxides with mixed electronic–ionic conduction are important catalysts for the oxygen reduction reaction in solid oxide fuel cells (SOFCs). Here, two cobalt‐free perovskite oxides, LaFe(0.8)Cu(0.2)O(3−δ) (LFCuO) and BaFe(0.8)Cu(0.2)O(3−δ) (BFCuO), were synthesized and comparatively studied with respect to their phase structures, oxygen contents, chemical defects, thermal expansion coefficient (TEC), as well as electrical and electrochemical properties. Different structures and properties have been found for each oxide, which have been interpreted based on their tolerance factors and chemical defects. LFCuO showed much better overall performance than BFCuO, and it proved to be a promising cobalt‐free cathode material of intermediate‐temperature SOFCs with a low TEC (12.0×10(−6) °C(−1)) that matches well with TECs of the electrolytes, high catalytic activity for the oxygen reduction reaction characterized by low area specific resistances (0.090 Ω cm(2) at 800 °C and 0.20 Ω cm(2) at 750 °C), and high‐temperature chemical stability with electrolytes.