Dual‐Doping Induced Synergistic Functionality in a Perovskite Air Electrode for Balanced Performance and Durability in Reversible Protonic Ceramic Cells

ABSTRACT The development of high‐performance air electrodes for reversible protonic ceramic cells (RPCCs) is constrained by the inherent trade‐off between electrocatalytic activity and operational stability. To address this challenge, a dual‐doping strategy was employed to dop Ti and Nb into PrBaCo ₂ O _5+δ , resulting in a novel triple‐conducting (H ⁺ /O ²⁻ /e ⁻ ) perovskite air electrode, PrBaCo _1.8 Ti _0.1 Nb _0.1 O _5+δ (PBCTN). The comprehensive characterization study demonstrates that the PBCTN oxide exhibits outstanding stability under high‐temperature and high‐humidity environments and show a polarization resistance as low as 0.06 Ω cm ² at 700°C. Density functional theory calculations reveal that optimized hydration energy, a more favorable O 2p band center, and accelerated surface reactions enhance the oxygen reduction and evolution kinetics. Through this design, the RPCC with the PBCTN air electrode achieves a peak power density of 1.12 W cm ⁻² at 700°C in fuel cell mode and a current density of 3.1 A cm ⁻² at 1.3 V in electrolysis mode, along with stable operation for over 380 h. This work provides insights into concurrently enhancing both activity and stability in electrocatalysts for advanced energy conversion technologies.