Effectively enhanced oxygen reduction activity and stability of triple-conducting composite cathodes by strongly interacting interfaces for protonic ceramic fuel cells

Abstract

Here, a novel triple-conducting composite cathode for protonic ceramic fuel cells, with superior oxygen reduction reaction (ORR) activity and stability, is developed by replacing cerium with zirconium in BaCo0.7(Ce0.8Y0.2)0.3O3−δ (BCCY) to construct strongly interacting interfaces. The one-step synthesized BaCo0.7(Zr0.8Y0.2)0.3O3−δ (BCZY) is composed of multiple phases with different functionalities, reaching a polarization resistance of 0.25 Ω cm2 at 600 °C while maintaining excellent performance stably for 206 h. The excellent ORR activity is attributed to the high concentration of active sites and the strong hydration capability at strongly interacting interfaces of Co-rich and Zr-rich phases which is introduced by the interdiffusion of Co and Zr. The low thermal expansion coefficient is also achieved through this interface, contributing to the excellent stability of BCZY. This study highlights the role of strongly interacting interfaces in enhancing the ORR activity and stability of materials and provides a new strategy for developing triple-conducting composite cathodes.