Evaluation of Fe-doped Pr_1.8Ba_0.2NiO₄ as a high-performance air electrode for reversible solid oxide cell

Cobalt and strontium-free Ruddelesden–Popper (RP) perovskite oxides are excellent air electrodes for reversible solid oxide cells (RSOCs). In this work, a novel Pr_1.8Ba_0.2Ni_1-xFe_xO₄ (denoted as PBNFx; x = 0, 0.05, 0.1, 0.15) RP perovskite air electrode is studied to evaluate its potential application in RSOCs. Fe-doped Pr_1.8Ba_0.2NiO₄ can promote surface oxygen exchange and ionic diffusion, thus reducing the polarization resistance (Rp) of the PBN electrode. The PBNF0.1 half-cell shows a low R_p value of 0.044 Ω cm² and good stability when operated in RSOC mode. The PBNF0.1 electrode exhibits excellent electrochemical performance and the highest oxygen vacancy concentration. In fuel cell mode, PBNF0.1 single cell reaches the maximum power density of 645 mW cm⁻², which is approximately 15 % higher than PBN (545 mW cm⁻²) at 800 °C. In electrolysis mode and at 1.3 V with 70 %H₂O at 800 °C, the PBNF0.1 single cell also exhibits a high electrolysis current density of 0.9 A cm⁻², which has improved by approximately 25 % of that of the PBN. Furthermore, the PBNF0.1 single cell achieves the current density of 665 mA cm⁻² at 1.4 V with 50 %CO₂ at 800 °C. Results demonstrate that PBNF0.1 is a potential air electrode for RSOCs.