Identification of O-rich structures on platinum(111)-supported ultrathin iron oxide films

SURFACE SCIENCE

卷:652

Article

Merte, Lindsay R.¹  Bai, Yunhai²  Zeuthen, Helene¹  Peng, Guowen²  Lammich, Lutz¹  Besenbacher, Flemming¹  Mavrikakis, Manos²  Wendt, Stefan¹ 

[1] Aarhus Univ, Interdisciplinary Nanosci Ctr iNANO, Dept Phys & Astron, DK-8000 Aarhus C, Denmark

[2] Univ Wisconsin, Dept Chem & Biol Engn, Madison, WI 53706 USA

关键词: Iron oxide;    O adatom dislocations;    FeO2 (-) (x) islands;    Catalysis;    Scanning tunneling microscopy (STM);    Density functional theory (DFT);   

DOI  :  10.1016/j.susc.2015.12.031

来源: Elsevier

【 摘 要 】

Using high-resolution scanning tunneling microscopy (STM) we have studied the oxidation of ultrathin FeO films grown on Pt(111). At the initial stage of the FeO film oxidation by atomic oxygen exposure, we identified three distinct types of line defects, all of which form boundaries between FeO domains of opposite orientation. Two types of line defects appearing bright (type-i) and dark (type-ii) in the STM images at typical scanning parameters are metallic, whereas the third line defect exhibits nonmetallic behavior (type-iii). Atomic-scale structure models of these line defects are proposed, with type-i defects exhibiting 4-fold coordinated Fe atoms, type-ii exhibiting 2-fold coordinated O atoms, and type-iii exhibiting tetrahedrally-coordinated Fe atoms. In addition, FeO2 trilayer islands are formed upon oxidation, which appear at FCC-type domains of the moire structure. At high scanning bias, distinct protrusions on the trilayer islands are observed over surface O ions, which are assigned to H adatoms. The experimental data are supported by density functional theory (DFT) calculations, in which bare and hydroxylated FeO2 trilayer islands are compared. Finally, we compare the formation of O-rich features on continuous FeO films using atomic oxygen with the oxidation of Pt(111)-supported FeO islands accomplished by O-2 exposure. (C) 2016 Elsevier B.V. All rights reserved.

【 授权许可】

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