A novel chemical composite strategy for synergistically enhancing the activity and stability of strontium-containing air electrode for protonic ceramic cells

Cation segregation on perovskite electrode surfaces usually leads to a decrease in the catalytic activity of electrodes and a shortened cell life. Herein, we have developed a simple and novel chemical composite strategy to achieve selectively surface reconstruction of the Sr-rich regions in perovskite Pr0.4Sr0.6Fe0.9Nb0.1O3-δ (PSFN), constructing strongly interacting interfaces between PSFN and Fe2O3 phases. The enhanced charge transfer between the two phases in PSFN/Fe2O3 is revealed by soft X-ray absorption spectroscopy. Meanwhile, fast surface oxygen exchange rate accelerates the migration and adsorption/desorption of oxygen species. The chemical composite electrode PSFN/Fe2O3 exhibits a smaller polarization resistance (0.35 Ω cm2) than that (0.61 Ω cm2) of the physical composite electrode PSFN + Fe2O3 at 600 °C in air. The distribution of relaxation time analyses demonstrate that enhanced reaction kinetics related to charge transfer and mass transfer are key factors in achieving stable operation of symmetric cell within 1000 h. Importantly, this study provides a simple and universal strategy for surface modification of perovskite oxides with cation separation issue, and highlights the crucial role of constructing strongly interacting interfaces in achieving high activity and stability of air electrodes.