Structure of Stoichiometric and Oxygen-Rich Ultrathin FeO(111) Films Grown on Pd(111)

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• 作者：Helene Zeuthen ; Wilhelmine Kudernatsch ; Guowen Peng ; Lindsay R. Merte ; Luis K. Ono ; Lutz Lammich ; Yunhai Bai ; Lars C. Grabow ; Manos Mavrikakis ; Stefan Wendt ; Flemming Besenbacher
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：July 25, 2013
• 年：2013
• 卷：117
• 期：29
• 页码：15155-15163
• 全文大小：746K
• 年卷期：v.117,no.29(July 25, 2013)
• ISSN：1932-7455

文摘

Monolayer thin FeO(111) films were grown on Pd(111) and oxidized by atomic oxygen (O). The stoichiometric and oxidized films were studied in detail by scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. Compared to the previously studied FeO(111)/Pt(111) system, small structural differences were observed for stoichiometric FeO monolayer films. Upon O exposure, the stoichiometric FeO film reconstructs, leading to the formation of new O-rich structures incorporating increasing amounts of additional O atoms. At low O exposures, the STM images exhibit bright features of regularly sized triangular structures assigned to O-adatom dislocation loops. A model of this O-rich structure composed of four-fold O-coordinated Fe atoms is proposed and confirmed by DFT calculations. Furthermore, these O dislocation loops induce the inversion of the FeO film and enclose portions of the film in which the order of the high-symmetry domains is inverted. For higher O exposures, the formation of FeO_2鈥?i>x islands coexisting with O-adatom dislocations and stoichiometric FeO patches was observed. These FeO_2鈥?i>x islands are reminiscent of the O-rich structures previously reported for FeO supported on Pt(111) and are catalytically active toward CO oxidation.