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 BaZr0.7Co0.3O3 nanocomposites when the doping concentration exceeds 30%, according to the present study. The construction of the BaCoO3/BaZr0.7Co0.3O3 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 BaZr0.4Co0.6O3 cathode produces a record‐breaking power density of 2253 mW cm−2 at 700°C.