Effective Promotion of the Activity and Stability of Cathodes for Protonic Ceramic Fuel Cells

Abstract Protonic ceramic fuel cells (PCFCs) are emerging as effective devices for their excellent capability of converting energy. However, the sluggish oxygen reduction reaction (ORR) and poor durability of cathodes greatly limit their widespread commercialization. Herein, a multi‐cationic oxide nano‐catalyst with a nominal composition of Pr_0.2Ce_0.2Ni_0.2Co_0.2Fe_0.2O_x (denoted as PCNCFO) is designed and reported, which significantly enhanced the ORR activity and durability of a typical PrBaCo₂O_5+δ (PBC) cathode. The PCNCFO‐coated PBC cathode delivered impressive cell performance with a small polarization resistance of only 0.18 Ω cm² at 600 °C on symmetrical cells and a high peak power density (PPD) of 1.31 W cm⁻² at 650 °C on single cells. Meanwhile, the PCNCFO‐coated PBC cathode exhibits excellent operational stability both on symmetrical and single cells. It is indicated that the Ce oxide in the nano‐catalyst coating can react with the segregated Ba to form active species, while others can activate the surface of the cathode, as indicated by the transmission electron microscope (TEM) and distribution of relaxation time (DRT) analyses.