Rational design of PrBaFe ₂O _{6− δ} -based cathodes for protonic ceramic fuel cells

Obtaining high-performance cathodes is critical for protonic ceramic fuel cells (PCFCs), as cathode performance significantly impacts fuel cell performance. A full understanding of the interactions among the diverse properties of cathode materials would benefit cathode design. In this study, PrBaFe₂O_6−δ (PBF) was doped with various dopants, including cobalt (Co), Ni, Cu, Zn, and Mn. Experiments and first-principles calculations are used to study the key properties of dopant-modified PrBaFe₂O_6−δ, including oxygen vacancy (V_O) creation, hydration ability, proton mobility, and oxygen reduction reaction (ORR) activity. There is no perfect dopant that can improve every property to its full potential. Instead, different dopants can impact different properties of the material. Co-dopant has the best cathode performance since it balances the material’s instinctive properties, even though it does not provide a significant advantage in the formation of V_O. PCFC utilizing Co-doped PrBaFe₂O_6−δ cathode has a high performance of 1680 mW·cm⁻² at 700 °C, which is greater than that of the other dopant-tailored PrBaFe₂O_6−δ cathodes reported in this study and is one of the largest ever recorded for PrBaFe₂O_6−δ-based cathodes for PCFCs. Co-doped PrBaFe₂O_6−δ cathode is further demonstrated to be robust, with excellent operational stability. This study not only provides a potential cathode candidate for PCFCs but also suggests an intriguing approach to cathode design by carefully examining and balancing different vital properties of the material.