Thermal Stability of In-Situ Exsolved Metallic Nanoparticles Structured Perovskite Type Hydrogen Electrode for Solid Oxide Cells

In this work, thermal stability of an in situ exsolved Ni–Fe nanoparticle structured Sr2Fe1.4Ni0.1Mo0.5O6 (SFMNi) perovskite type hydrogen electrode is studied by examining the evolution of electrode polarization resistance and material morphology. During the 745-h durability testing, the polarization resistance measured at 800 °C dramatically decreases from 0.68 to 0.31 Ω cm2 with an activation rate of 22.92%/100 h in the initial 200 h, then undergoes a stable period in the following 200 h, and subsequently rises to 0.40 Ω cm2 with a degradation rate of 6.20%/100 h in the last 345 h. Variation of electrode electrochemical performance could be explained by the morphology evolution of the exsolved nanoparticles, which are well-fitted by the self-limiting growth model. Distribution of relaxation time analysis results indicate that gas conversion is the primary rate-limiting step during the electrode reaction and can be effectively accelerated by the gradually exsolved Ni–Fe nanoparticles during the durabili...