Cerium and Gadolinium co-doped perovskite oxide for a protonic ceramic fuel cell cathode

Proton-conducting ceramic fuel cells (PCFCs) show unique advantages over oxygen-ionic-conducting counterparts at intermediate and low temperatures, which have attracted significant attention worldwide in recent years. A critical issue for world-spread applications is inadequate performance due to the lack of appropriate cathodes for PCFCs. Here, cubic perovskite BaCo0.4Fe0.5-xCe0.1RexO3-δ (ReY, Gd x = 0, 0.1) materials are successfully synthesized and evaluated as the cathode in the PCFCs based on BaCe0.7Zr0.1Y0.1Yb0.1O3-δ as an electrolyte material. The Y- or Gd-doped perovskite BaCo0.4Fe0.4Ce0.1Y0.1O3-δ (BCFCeY), BaCo0.4Fe0.4Ce0.1Gd0.1O3-δ (BCFCeG) exhibit larger lattice parameters, and higher electrocatalytic activity comparing to their parent oxide BaCo0.4Fe0.5Ce0.1O3-δ (BCFCe). Among them, BCFCeG shows the best performance. The single cell with BCFCeG as the cathode material exhibits an interfacial polarization resistance as low as 0.12 Ω cm2 and delivers a promising peak power density of 504 mW cm−2 at 600 °C, while the BCFCe-based cell achieves only 437 mW cm−2 at 600 °C. The X-ray diffraction (XRD) results show good chemical compatibility for BCFCeG below 1050 °C. Moreover, it shows favorable stability in CO2-containing environment. This work confirms that BCFCeG could be a promising cathode for PCFCs.