Developing High-Performance Low-Temperature Ceramic Fuel Cells Using an Acidic-Etched LaFe2O4–WO3 Heterostructure Composite Cathode

Efficient oxygen reduction reaction (ORR) electrocatalysts are important for developing high-performance electrochemical energy devices. Especially, the ceramic fuel cells suffer from the poor ORR activity at cathode surface when operating at lower temperature range. Here, we report an acidic etching approach to improve the ORR activity of the LaFe₂O₄–WO₃ composite cathode. The LaFe₂O₄–WO₃ heterostructure cathode material has shown an improved ORR activity when operating at 450–550 °C after acidic etching in H₂SO₄. The H₂SO₄-etched LaFe₂O₄–WO₃ cathode has exhibited an area-specific-resistance (ASR) of only 0.18 Ω cm² and an impressive power density of 782 mW·cm^–2 at 550 °C using proton conducting BaZr_0.2Ce_0.7Y_0.1O₃ electrolyte. The use of acidic etching to modify the surface of the LaFe₂O₄–WO₃ composite is found to be an effective strategy. By introducing surface defects and increasing the specific surface area, the acidic treatment can significantly enhance the electrochemical performance by providing more active sites for the oxygen reduction reaction (ORR). Furthermore, this modification may improve the interfacial interaction between LaFe₂O₄ and WO₃, thereby facilitating better electron and ion transport within the composite cathode. However, this methodology can be considered to develop high-performance low-temperature cathode materials.