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

Abstract

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 moiré 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 O₂ exposure.

Authors:

Merte, Lindsay R. ^[1]; Bai, Yunhai ^[2]; Zeuthen, Helene ^[1]; Peng, Guowen ^[2]; Lammich, Lutz ^[1]; Besenbacher, Flemming ^[1]; Mavrikakis, Manos ^[2]; Wendt, Stefan ^[1]

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+ Show Author Affiliations

1. Aarhus Univ., Aarhus (Denmark)
2. Univ. of Wisconsin-Madison, Madison, WI (United States)

Publication Date:

Wed Jan 06 00:00:00 EST 2016

Research Org.:

Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

Contributing Org.:

EMSL; the Center for Nanoscale Materials at Argonne National Laboratory (ANL); the National Energy Research Scientific Computing Center (NERSC); DoD High Performance Computing Modernization Program (US Air Force Research Laboratory DoD Supercomputing Resource Center (AFRL DSRC), the US Army Engineer Research and Development Center (ERDC), and the Navy DoD Supercomputing Resource Center (Navy DSRC)

OSTI Identifier:

1397266

Alternate Identifier(s):

OSTI ID: 1398118

Grant/Contract Number:  

FG02-05ER15731; AC02-06CH11357; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Surface Science

Additional Journal Information:

Journal Volume: 652; Journal Issue: C; Journal ID: ISSN 0039-6028

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Iron oxide; O adatom dislocations; FeO2 − x islands; Catalysis; Scanning tunneling microscopy (STM); Density functional theory (DFT)