High-performance Co-free dual-phase perovskite positrodes for protonic ceramic cells: Zn and Ni-doped BaCe0.2Fe0.8O3-δ system

Protonic ceramic cells (PCCs) can convert the energy between electricity and fuels efficiently, and are attracting increasing attention. However, the development of PCCs is restricted by the lack of proper positrode materials. In this work, we report a Co-free system with a nominal composition of BaCe 0.2 Fe 0.8 O 3-δ , which is composed of a Fe-rich matrix phase decorated with Ce-rich nanoparticles. The performance of such a dual-phase positrode system is further improved by doping Zn and/or Ni to increase bulk and surficial concentration of oxygen vacancies. The hydration reaction and surficial adsorption of oxygen species are thereby promoted, benefitting the oxygen reduction reaction. The Ni and Zn co-doped composition Ba(Ce 0.2 Fe 0.8 ) 0.85 (Ni 0.5 Zn 0.5 ) 0.15 O 3-δ exhibits lower polarization resistance than the pristine and singly doped systems, enabling the fuel cells to show high peak power densities of 400, 721, and 828 mW cm −2 at 550, 600, and 650 °C, respectively.