The influence of A-site deficiency on the electrochemical properties of (Ba0.95La0.05)1-xFeO3-δ as an intermediate temperature solid oxide fuel cell cathode

Developing cathodes capable of working at intermediate temperatures (IT) is key to improving solid oxide fuel cells’ (SOFC) durability, ease of operation, and manufacturing cost reduction. BaFeO3-δ (BFO)-based perovskites are ideal candidates because of their fast kinetics, which is due to the mixed conduction of oxygen vacancies and electron-holes. Thus, maximizing their oxygen vacancy and hole concentration can further enhance oxygen reduction reaction (ORR) catalysis. This work proposes to achieve this by generating A-site deficiency, which introduces negative charges into the perovskite crystal. The paper presents a computational and experimental analysis of this strategy on BFO-based cathodes, using (Ba0.95La0.05)1-xFeO3-δ as a case study. A-site deficiency increases the concentration of oxygen vacancies and holes, improving ORR catalysis. In addition, it eases oxygen surface exchange by hindering Ba segregation. As a result, A-site deficiency improves the overall electrochemical properties of BFO-based cathodes, providing a simple and effective method to enhance their performance.