Probing the role of Fe and Sr co-doped BaZrO3 for enhanced cathode performance in protonic ceramics fuel cells

Cathode materials greatly govern the performance of protonic ceramics fuel cells (PCFCs), and development of suitable cathodes for PCFCs now becomes important. In this study, the traditional proton conductor BaZrO 3 is tailored with Sr and Fe elements, aiming to design proper cathodes for PCFCs. The structural, electronic, and catalytic effects of dual-element doping on BaZrO 3 -based materials are systemically investigated. Experimental and computational analyses reveal that a 75 % iron doping concentration (BaZr 0 · 25 Fe 0 · 75 O 3 ) markedly enhances oxygen vacancy concentration, reduces proton migration barriers, and elevates electrical conductivity. Notably, moderate strontium doping (50 %) synergistically improves performance, whereas excessive doping (75 %) induces adverse effects on oxygen vacancy concentration, proton migration, and electrical conductivity. The optimized Ba 0 · 5 Sr 0 · 5 Zr 0 · 25 Fe 0 · 75 O 3 cathode achieves a peak power density of 945 mW cm -2 at 700 °C. These findings elucidate the interplay between dopant elements, doping concentrations, and material properties related to electrochemical performance, offering actionable strategies for designing high-performance PCFC cathodes.