Enhancing proton-conducting solid oxide fuel cell performance with Pr-doped BaZr0.5Fe0.5O3-δ cathodes

Abstract

Developing high-performance cathodes remains crucial for advancing proton-conducting solid oxide fuel cells (H-SOFCs). While Fe-doped BaZrO₃ (BZF), derived from the proton conductor BaZrO₃, demonstrates moderate performance, it underperforms compared to recently reported cathodes. To address this limitation, we introduce Pr as a co-dopant in BZF, creating BaZr_0.4Fe_0.5Pr_0.1O₃ (BZFPr). Pr-doping induces electronic structure modifications that weaken metal-oxygen bonds, generating abundant oxygen vacancies and enhancing protonation capabilities. These changes synergistically improve oxygen and proton diffusion kinetics. Furthermore, Pr doping elevates the oxidation state of Fe, significantly boosting oxygen reduction reaction (ORR) activity. After microstructural optimization, BZFPr achieves exceptional performance with a peak power density of 1686 mW cm⁻² and a low polarization resistance of 0.059 Ω cm² at 700 °C—values surpassing most state-of-the-art cathodes. The BZFPr cathode also exhibits remarkable operational stability under fuel cell conditions, establishing Pr doping as an effective strategy for developing high-performance, durable cathodes for H-SOFCs.