Ceria (CeO₂) is a promising metal-oxide support that is used in three-way catalysis (TWC). The activity of ceria-supported TWC depends on the location and concentration of oxygen vacancies. Oxygen diffusion can occur once the oxygen vacancy was created, and it leads to enhanced catalytic activity. In this study, the density-functional tight-binding method was used to estimate the free-energy barriers of oxygen diffusion in bulk CeO₂ and on the (111)-CeO₂ surface. The reconstructed free-energy surfaces from metadynamics sampling show that the diffusion in the bulk CeO₂ is faster than that on the (111)-CeO₂ surface, with activation barriers of 7.4 and 31.6 kcal/mol, respectively.

中文翻译：

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散装CeO2或（111）-CeO2表面的氧气扩散速度更快吗？理论研究

二氧化铈（CeO ₂）是一种有前途的金属氧化物载体，用于三元催化（TWC）。氧化铈负载的TWC的活性取决于氧空位的位置和浓度。一旦产生氧空位，就会发生氧扩散，并导致催化活性增强。在这项研究中，使用密度泛函紧密结合方法来估计本体CeO _2中和（111）-CeO ₂表面上氧扩散的自由能垒。通过元动力学采样重建的自由能表面表明，在本体CeO ₂中的扩散要快于（111）-CeO ₂表面上的扩散，其激活势垒分别为7.4和31.6 kcal / mol。