Dewetting Transition of CoO/Pt(111) in CO Oxidation Conditions Observed In Situ by Ambient Pressure STM and XPS

TY - JOUR

T1 - Dewetting Transition of CoO/Pt(111) in CO Oxidation Conditions Observed In Situ by Ambient Pressure STM and XPS

AU - Rattigan, Eoghan

AU - Jensen, Sigmund

AU - Sun, Zhaozong

AU - Niño, Miguel Angel

AU - Parreiras, Sofia O.

AU - Martín-Fuentes, Cristina

AU - Martín Romano, Juan Carlos

AU - Écija, David

AU - Escudero, Carlos

AU - Villar-Garcia, Ignacio J.

AU - Wendt, Stefan

AU - Rodríguez-Fernández, Jonathan

AU - Lauritsen, Jeppe V.

PY - 2023/5

Y1 - 2023/5

N2 - Ultrathin cobalt oxide films supported on noble-metal surfaces have received much attention as interesting examples of low-temperature CO oxidation catalysts. It is expected that the activity of the cobalt oxides is closely linked with the structure and morphology of the film, but a direct operando correlation between CO oxidation activity, nanoscale structure, oxidation state, and surface composition has been missing. Here, we use a combination of operando ambient pressure scanning tunneling microscopy and ambient pressure X-ray photoelectron spectroscopy to investigate varying submonolayer coverages of CoO supported on Pt(111) under CO oxidation conditions. The goal is to compare the structural and spectroscopic features as the samples are exposed to O-rich CO/O2 gas mixtures at millibar pressure and brought to temperatures where CO oxidation occurs. Upon first exposure to millibar gas mixtures, the initial bilayer CoO film is oxidized to trilayer CoO2, characterized by a preserved film morphology and Co in a predominant 3+ oxidation state. However, upon temperature increase during the CO oxidation reaction, the cobalt oxide ultrathin film undergoes dewetting into nanoparticles. On the basis of the XPS signature, we conclude that these nanoparticles have a Co3O4-like structure. The results underline the importance of operando observations of surface structures. This new insight into the Co oxide/metal interface may aid in our understanding of reactivity of metal oxide coated noble-metal particles in general.

AB - Ultrathin cobalt oxide films supported on noble-metal surfaces have received much attention as interesting examples of low-temperature CO oxidation catalysts. It is expected that the activity of the cobalt oxides is closely linked with the structure and morphology of the film, but a direct operando correlation between CO oxidation activity, nanoscale structure, oxidation state, and surface composition has been missing. Here, we use a combination of operando ambient pressure scanning tunneling microscopy and ambient pressure X-ray photoelectron spectroscopy to investigate varying submonolayer coverages of CoO supported on Pt(111) under CO oxidation conditions. The goal is to compare the structural and spectroscopic features as the samples are exposed to O-rich CO/O2 gas mixtures at millibar pressure and brought to temperatures where CO oxidation occurs. Upon first exposure to millibar gas mixtures, the initial bilayer CoO film is oxidized to trilayer CoO2, characterized by a preserved film morphology and Co in a predominant 3+ oxidation state. However, upon temperature increase during the CO oxidation reaction, the cobalt oxide ultrathin film undergoes dewetting into nanoparticles. On the basis of the XPS signature, we conclude that these nanoparticles have a Co3O4-like structure. The results underline the importance of operando observations of surface structures. This new insight into the Co oxide/metal interface may aid in our understanding of reactivity of metal oxide coated noble-metal particles in general.

UR - http://www.scopus.com/inward/record.url?scp=85159585673&partnerID=8YFLogxK

U2 - 10.1021/acs.jpcc.3c01045

DO - 10.1021/acs.jpcc.3c01045

M3 - Journal article

AN - SCOPUS:85159585673

SN - 1932-7447

VL - 127

SP - 8547

EP - 8556

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

IS - 18

ER -