Modifications of mixed ionic electronic conductor (MIEC) surfaces are a promising approach to improve oxygen exchange reaction (OER) kinetics and can have a tremendous impact on surface charges and secondary ion yields. Utilizing time-of-flight secondary ion mass spectrometry (ToF-SIMS), we examined degradation, segregation, and cation interdiffusion behaviors on La0.6Sr0.4CoO3-δ (LSC) and Pr0.2Ce0.8O2-δ (PCO) thin films modified with ∼0.5 nm CaO, TiO2, and SnO2 overlayers after annealing at 700 °C and 800 °C, respectively. Surface profiles (AFM; ToF-SIMS) and depth profiles (ToF-SIMS) revealed structural and chemical transformations, including particle formation and surface roughening. The overlayer stability varied significantly for different overlayers on the same material and for the same overlayer on LSC and PCO. All oxidic overlayers were more stable on PCO than LSC. Depth profiling indicated that 40Ca+ ions penetrated the entire LSC and PCO layers (30 nm). 48Ti+ aligns more accurately with a typical analytical solution to Fick’s diffusion equation for finite systems, showing higher diffusion coefficients in LSC than PCO. 120Sn+ exhibited minimal penetration, indicating high stability on the surface and less intermixing with either MIEC. These results hint at the need to differentiate between the stability of the binary oxides on the surface and the bulk diffusivity.

中文翻译：

---

使用 ToF-SIMS 研究混合离子电子导体上的亚纳米二元氧化表面修饰：氧化覆盖层稳定性和离子相互扩散行为


混合离子电子导体 （MIEC） 表面的改性是改善氧交换反应 （OER） 动力学的一种很有前途的方法，可以对表面电荷和二次离子产率产生巨大影响。利用飞行时间二次离子质谱 （ToF-SIMS），我们研究了在 700 °C 和 800 °C 退火后，用 ∼0.5 nm CaO、TiO2 和 SnO2 外层修饰的 La0.6Sr0.4CoO3-δ （LSC） 和 Pr0.2Ce0.8O2-δ （PCO） 薄膜的降解、偏析和阳离子相互扩散行为。表面轮廓 （AFM;ToF-SIMS） 和深度剖面 （ToF-SIMS） 揭示了结构和化学转变，包括颗粒形成和表面粗糙化。同一材料上不同上层以及同一上层在 LSC 和 PCO 上的上层稳定性差异显著。所有氧化覆盖层在 PCO 上都比 LSC 更稳定。深度剖分表明 40Ca+ 离子穿透了整个 LSC 和 PCO 层 （30 nm）。48Ti+ 更准确地与有限系统的 Fick's 扩散方程的典型解析解一致，显示 LSC 中的扩散系数高于 PCO。120Sn+ 表现出最小的穿透力，表明在表面具有高稳定性并且与任一 MIEC 的混合较少。这些结果表明，需要区分表面二元氧化物的稳定性和体扩散率。