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

TY - JOUR

T1 - Identification of O-rich structures on platinum(111)-supported ultrathin iron oxide films

AU - Merte, Lindsay R.

AU - Bai, Yunhai

AU - Zeuthen, Helene

AU - Peng, Guowen

AU - Lammich, Lutz

AU - Besenbacher, Flemming

AU - Mavrikakis, Manos

AU - Wendt, Stefan

PY - 2016/10

Y1 - 2016/10

N2 - 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, FeO 2 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 FeO 2 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.

AB - 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, FeO 2 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 FeO 2 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.

KW - ACTIVE-SITES

KW - AUGMENTED-WAVE METHOD

KW - BASIS-SET

KW - CATALYTIC-OXIDATION

KW - Catalysis

KW - Density functional theory (DFT)

KW - FeO2 (-) (x) islands

KW - Iron oxide

KW - METAL-SUPPORT INTERACTIONS

KW - O adatom dislocations

KW - OXYGEN

KW - PT(111)

KW - STM

KW - Scanning tunneling microscopy (STM)

KW - TEMPERATURE CO OXIDATION

KW - TOTAL-ENERGY CALCULATIONS

UR - http://www.scopus.com/inward/record.url?scp=84955578607&partnerID=8YFLogxK

U2 - 10.1016/j.susc.2015.12.031

DO - 10.1016/j.susc.2015.12.031

M3 - Journal article

SN - 0039-6028

VL - 652

SP - 261

EP - 268

JO - Surface Science

JF - Surface Science

ER -