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 BaZrO 3 can result in the development of BaCoO 3 and BaZr 0.7 Co 0.3 O 3 nanocomposites when the doping concentration exceeds 30%, according to the present study. The construction of the BaCoO 3 /BaZr 0.7 Co 0.3 O 3 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 0.4 Co 0.6 O 3 cathode produces a record-breaking power density of 2253 mW cm -2 at 700°C.