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Atomic and Electronic Edge Structures of Monolayer Ceria on Pt(111)

Zhichao Huang, Cheng Han,* Yi-Yang Sun,* Kai Wu,* and Wei Chen* 


Ceria (CeO2) on Pt(111) has been widely studied in model catalysis due to the strong interfacial interaction between CeO2 and platinum (Pt). Although extensive studies have been conducted on monolayered CeO2 islands on the Pt(111) surface, the atomic and electronic structures of the island edge are still elusive. Herein, density functional theory calculations are employed to simulate the CeO2(111) surface, the CeO2 monolayer on Pt(111), and their edges. It is found that unlike the outmost O−Ce−O layer of CeO2(111), the CeO2 layer on Pt(111) is negatively charged and has non-zero magnetic moments. For the CeO2(111) surface, the stoichiometric-type edge is the most stable, and the atomic orders of two edges from outside in are Os2−−Ce4+−Oi2− and Oi2−−Ce4+−Os2−. For the CeO2/Pt(111) surface, however, only at high temperature and under ultra-high vacuum conditions, the most stable edge is the same as thatof CeO2(111). Otherwise, an oxygen-rich edge will be formed, where the atomic orders of two edges from outside in are Oi2−−Os2−−Ce4+ and Oi2−−Ce4+−Os2−. Furthermore, the adsorption energy of the K ion on the Oi2−−Os2−−Ce4+-type edge is lower thanthat on the Oi2−−Ce4+−Os2−-type edge, indicating a stronger adsorbability of the Oi2−−Os2−−Ce4+-type edge toward positivelycharged ions. The edge structures proposed here and the corresponding electronic properties provide an insight into the interaction between CeO2 and the Pt surface, which helps to understand the catalytic mechanism on the CeO2/Pt(111) surface.