Enhanced oxygen reduction reaction activity of BaCe0.2Fe0.8O3-δ cathode for proton-conducting solid oxide fuel cells via Pr-doping

Funding Information: The financial support from National Natural Science Foundation of China under contract number 22075205 and the support of Tianjin Municipal Science and Technology Commission under contract number 19JCYBJC21700 are gratefully acknowledged. The work has been also supported by the Program of Introducing Talents to the University Disciplines under file number B06006, and the Program for Changjiang Scholars and Innovative Research Teams in Universities under file number IRT 0641. Publisher Copyright: © 2021 Elsevier B.V. Copyright: Copyright 2021 Elsevier B.V., All rights reserved. BaCe0.2Fe0.8-xPrxO3-δ (x = 0–0.3) is studied as a cobalt-free cathode material for proton-conducting solid oxide fuel cells. The cathode is composed of a cubic BaFeO3-δ phase and an orthorhombic BaCeO3-δ phase, and Pr is doped in both phases. The partial substitution of Pr for Fe decreases the content of the BaFeO3-δ phase, leading to a lower electrical conductivity. BaCe0.2Fe0.6Pr0.2O3-δ has the most adsorbed oxygen and Fe3+ on the surface, resulting in the fastest oxygen surface exchange kinetics and the highest activity. The partial pressure of H2O shows a negligible effect on the polarization resistance of the cathode. In contrast, the polarization resistance increases remarkably with the decrease of oxygen partial pressure, indicating that the rate of the cathode process is controlled by the surface exchange of oxygen. At 700 °C, BaCe0.2Fe0.6Pr0.2O3-δ shows the lowest polarization resistance of 0.057 Ω cm2, and a single cell with that cathode exhibits the highest maximum power density of 562 mW cm−2. Theresults demonstrate that Pr doped BaCe0.2Fe0.8O3-δ is a promising cobalt-free cathode material for proton-conducting solid oxide fuel cells.