Density Functional Theory plus Hubbard U Study of the Segregation of Pt to the CeO2–x Grain Boundary
Density Functional Theory plus Hubbard U Study of the Segregation of Pt to the CeO2–x Grain Boundary
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密度泛函理论结合 Hubbard U 研究 Pt 在 CeO2–x 晶界上的偏析
DOI：
10.1021/acs.nanolett.7b04680
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发表时间：
2018
期刊：
影响因子：
10.8
通讯作者：
Ying Liu
中科院分区：
文献类型：
--
作者：
Guoli Zhou;Pan Li;Qingmin Ma;Zhixue Tian;Ying Liu
晶界（GB）可用作溶质原子和缺陷的陷阱，偏析物和晶界之间的相互作用对于理解纳米晶材料的性能至关重要。在本研究中，我们系统地研究了二氧化铈 (CeO2) 中 Σ3 (111) GB 处的 Pt 偏析和 Pt-氧空位相互作用。 Pt原子向Σ3(111)GB偏析的倾向比向(111)和(110)自由表面偏析的倾向强，但比向(112)和(100)自由表面偏析的倾向弱。晶格畸变在 Pt 偏析中起主导作用。在 Pt 分离的晶界 (Pt@GB) 处，氧空位更倾向于在晶界区域中的 Pt 附近自发形成。然而，在原始GB中，氧空位只能在贫氧条件下形成。因此，Pt偏析到GB促进了氧空位的形成，并且它们的强相互作用增强了界面凝聚力。我们提出，靠近纳米晶二氧化铈表面制造的GB可以从晶粒内部或其他类型的表面捕获Pt，从而抑制氧化还原反应下Pt在表面上的积累，特别是在贫氧条件下。
Grain boundaries (GBs) can be used as traps for solute atoms and defects, and the interaction between segregants and GBs is crucial for understanding the properties of nanocrystalline materials. In this study, we have systematically investigated the Pt segregation and Pt–oxygen vacancies interaction at the ∑3 (111) GB in ceria (CeO2). The Pt atom has a stronger tendency to segregate to the ∑3 (111) GB than to the (111) and (110) free surfaces, but the tendency is weaker than to (112) and (100). Lattice distortion plays a dominant role in Pt segregation. At the Pt-segregated-GB (Pt@GB), oxygen vacancies prefer to form spontaneously near Pt in the GB region. However, at the pristine GB, oxygen vacancies can only form under O-poor conditions. Thus, Pt segregation to the GB promotes the formation of oxygen vacancies, and their strong interactions enhance the interfacial cohesion. We propose that GBs fabricated close to the surfaces of nanocrystalline ceria can trap Pt from inside the grains or other types of surface, resulting in the suppression of the accumulation of Pt on the surface under redox reactions, especially under O-poor conditions.