Ostwald ripening is a leading cause of the degradation of platinum group catalysts at high temperature in an oxidizing atmosphere. Recent experiments suggested that volatile species can be trapped on ceria, forming atomically dispersed active catalytic sites instead of large nanoparticles. Here we present a comparative density functional theory study of the interaction of PtO₂(g), the most likely volatile species responsible for the process of Ostwald ripening, with various surfaces. Defect-free CeO₂(111) and Al₂O₃(100) surfaces have a very small binding energy towards PtO₂(g) compared to the platinum surface, indicative of particle growth. However, the stepped edge of the CeO₂(111) surface effectively traps the mobile species, generating atomically dispersed catalysts. Such trapped single-atom platinum-on-ceria catalysts are predicted to have a square-planar [PtO₄] structure, with the platinum atom strongly binding to the surface, preventing platinum atoms from aggregating into larger nanoparticles. These results provide an atomic insight into the single atom trapping and suggest a route for the development of sinter-resistant catalysts.

中文翻译：

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奥斯特瓦尔德熟化与单原子俘获：了解铂粒子烧结

奥斯特瓦尔德熟化是高温下在氧化气氛中铂​​基催化剂降解的主要原因。最近的实验表明，挥发性物质可以被捕获在二氧化铈上，形成原子分散的活性催化位点，而不是大的纳米颗粒。在这里，我们对PtO ₂（g）的相互作用进行了比较密度泛函理论研究，PtO ₂（g）是奥斯特瓦尔德（Ostwald）熟化过程中最可能的挥发性物质，具有多种表面。与铂表面相比，无缺陷的CeO ₂（111）和Al ₂ O ₃（100）表面对PtO ₂（g）的结合能非常小，表明颗粒生长。但是，CeO ₂的阶梯状边缘（111）表面有效地捕获了可移动的物质，产生了原子分散的催化剂。据预测，这种捕集的单原子二氧化铈铂催化剂具有正方形[PtO ₄ ]结构，铂原子与表面牢固结合，可防止铂原子聚集成较大的纳米粒子。这些结果提供了对单原子捕集的原子洞察力，并提出了开发抗烧结催化剂的途径。