Enhanced Electrochemical Performance and Durability of the BaCo_0.4Fe_0.4Zr_0.1Y_0.1O_3-δComposite Cathode of Protonic Ceramic Fuel Cells via Forming Nickel Oxide Nanoparticles

In protonic ceramic fuel cells (PCFCs), oxygen reduction reaction activity is governed by the oxygen adsorption/dissociation, proton conduction, and electron transfer kinetics. Although various strategies have been explored to enhance the proton and electron conductivity via tuning the oxygen vacancy concentration in the electrode materials and introducing electronic conducting agents, there are few studies on improving oxygen adsorption/dissociation (surface-exchange reaction) kinetics in PCFCs. In this study, we report uniformly distributed thermodynamically stable nickel oxide (NiO) nanoparticles as a catalyst to enhance the electrochemical performance of the BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY) cathode, which is a promising cathode material because of its triple (oxygen ion, proton, and electron) conductivity in PCFCs, by improving surface-exchange reaction kinetics. The 0D NiO nanoparticles with high adsorption and fast dissociation ability of oxygen could enlarge the active sites for surface-exchange reactions without fading the BCFZY surface and triple-phase boundaries where the H2O formation reaction occurs. The cathode employing NiO nanoparticles exhibits largely reduced polarization resistance and a superior power density of 780 mW/cm2 at 600 °C. This improvement is attributed to the enhanced surface-exchange reaction kinetics.