An In Situ Formed, Dual-Phase Cathode with a Highly Active Catalyst Coating for Protonic Ceramic Fuel Cells

Composite cathodes of solid oxide fuel cells (SOFCs) are normally fabricated by mechanical mixing of electronic- and ionic-conducting phases. Here, a dual-phase SOFC cathode, composed of perovskite PrNi0.5Mn0.5O3 (PNM) and exsoluted fluorite PrOx particles, produced in situ through a glycine-nitrate solution combustion process, is reported. When applied as the cathode for a BaZr0.1Ce0.7Y0.1Yb0.1O3-based protonic ceramic fuel cell, the hybrid cathode displays excellent electrocatalytic activity (area-specific resistance of 0.052 cm(2) at 700 degrees C) and remarkable long-term stability when operated at a cell voltage of 0.7 V for approximate to 500 h using H-2 as fuel and ambient air as oxidant. The excellent performance is attributed to the proton-conducting BaPrO3-based coating and high-concentration oxygen vacancies of a Ba-doped PNM surface coating, produced by the reaction between the cathode and Ba from the electrolyte (via evaporation or diffusion), as confirmed by detailed X-ray photoelectron spectroscopy, Raman spectroscopy, and density functional theory-based calculations.