Unveiling the importance of the interface in nanocomposite cathodes for proton-conducting solid oxide fuel cells

Designing a high-performance cathode is essential for the development of proton-conducting solid oxide fuel cells (H-SOFCs), and nanocomposite cathodes have proven to be an effective means of achieving this. However, the mechanism behind the nanocomposite cathodes' remarkable performance remains unknown. Doping the Co element into BaZrO₃ can result in the development of BaCoO₃ and BaZr_0.7Co_0.3O₃ nanocomposites when the doping concentration exceeds 30%, according to the present study. The construction of the BaCoO₃/BaZr_0.7Co_0.3O₃ interface is essential for the enhancement of the cathode catalytic activity, as demonstrated by thin-film studies using pulsed laser deposition to simulate the interface of the BCO and BZCO individual particles and first-principles calculations to predict the oxygen reduction reaction steps. Eventually, the H-SOFC with a BaZr_0.4Co_0.6O₃ cathode produces a record-breaking power density of 2253 mW cm^-2 at 700°C.