Abstract Pt monolayer-based core-shell catalysts have garnered significant interest for the application of low temperature fuel cell technology as their use may enable a decreased loading of Pt while still providing sufficient current density to meet volumetric requirements. One promising candidate in this class of materials is a Pd@Pt core-shell catalyst, which shows enhanced activity toward oxygen reduction reaction (ORR). One concern with the use of Pd@Pt, however, is the durability of the core-shell structure as Pd atoms are thermodynamically favored to migrate to the surface. The pathway of the migration has not been systematically studied. The current study explores the stability of this structure to thermal annealing and probes the effect of this heat treatment on the catalyst surface structure and its oxygen reduction activity. It was found that surface alloying between Pd and Pt occurs at temperatures as low as 200 °C, and significantly alters the structure and ORR catalytic activity in the range of 200–300 °C. Our results shed lights on the thermal induced interatomic diffusion in all core-shell and thin film structures.

中文翻译：

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Pd-Pt核壳纳米粒子中的原子间扩散

摘要 Pt 单层基核壳催化剂在低温燃料电池技术的应用中引起了极大的兴趣，因为它们的使用可以降低 Pt 的负载量，同时仍然提供足够的电流密度以满足体积要求。此类材料中的一个有希望的候选者是 Pd@Pt 核壳催化剂，它对氧还原反应 (ORR) 显示出增强的活性。然而，使用 Pd@Pt 的一个问题是核壳结构的耐久性，因为 Pd 原子在热力学上有利于迁移到表面。尚未系统地研究迁移的途径。目前的研究探索了这种结构对热退火的稳定性，并探讨了这种热处理对催化剂表面结构及其氧还原活性的影响。发现 Pd 和 Pt 之间的表面合金化发生在低至 200°C 的温度下，并在 200-300°C 范围内显着改变结构和 ORR 催化活性。我们的结果阐明了所有核壳和薄膜结构中的热诱导原子间扩散。