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

Abstract 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 PrNi 0.5 Mn 0.5 O 3 (PNM) and exsoluted fluorite PrO x particles, produced in situ through a glycine–nitrate solution combustion process, is reported. When applied as the cathode for a BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3 ‐based protonic ceramic fuel cell, the hybrid cathode displays excellent electrocatalytic activity (area‐specific resistance of 0.052 Ω cm 2 at 700 °C) and remarkable long‐term stability when operated at a cell voltage of 0.7 V for ≈500 h using H 2 as fuel and ambient air as oxidant. The excellent performance is attributed to the proton‐conducting BaPrO 3 ‐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.