A cobalt free triple charge conducting Sm0.2Ce0.8O2-δ-Ba0.5Sr0.5Fe0.8Sb0.2O3-δ heterostructure composite cathode for protonic ceramic fuel cell

Protonic ceramic fuel cells (PCFCs) are considered more capable of operating at low temperature than solid oxide fuel cells (SOFCs) e.g., at 300-600 degrees C because of low activation energy associated with proton transport if suitable cathodes can be developed. Herein, we have developed a cobalt-free triple charge conducting (oxygen ion, proton and electron-hole) Sm0.2Ce0.8O2-delta-Ba0.5Sr0.5Fe0.8Sb0.2O3-delta (SDC-BSFSb) heterostructure composite for PCFC cathode. The SDC-BSFSb exhibit very low-area-specific resistance with large oxygen reduction reaction (ORR) activity over barium-ceria-based proton conducting perovskite-oxide electrolytes. We have demonstrated high-power densities of 705 mW-cm(2) for a button-sized PCFC at 550 degrees C using H-2/air fuels, and even with possible operation at 400 degrees C. Various spectroscopic measurements such as X-ray photoelectron, U-visible, Raman, and Density Functional Theory (DFT) calculations were employed to understand the improved ORR electrocatalyst function of SDC-BSFSb heterostructure composite for PCFCs cathode. It is found that SDC-BSFSb effectively showed enhanced ionic and electronic properties to exhibit high ORR at the interface of SDC and BSFSb particles. The results can further help to develop functional cobalt-free electro-catalysts for LT-PCFCs/LT-SOFCs and other related applications.