Details
| Original language | English |
|---|---|
| Pages (from-to) | 26864-26872 |
| Number of pages | 9 |
| Journal | Journal of Physical Chemistry C |
| Volume | 120 |
| Issue number | 47 |
| Publication status | Published - 18 Nov 2016 |
Abstract
In pattern-forming reaction systems, the conversion of macroscopic islands of chemisorbed oxygen into low work function (WF) areas has been attributed to formation of a subsurface oxygen species. We prepare micrometer-sized oxygen islands on Pt(100) and Pt(110) by reaction fronts in catalytic CO oxidation in the 10−6 mbar range. By applying electron microscopy with chemical and structural sensitivity, we characterize their chemical composition upon annealing in vacuum. On Pt(100) we reproduce the previously reported transformation from high to low WF, estimating a relative change Δϕ ≈-0.8 eV with respect to the CO covered surface. We demonstrate that the change in WF is due to a strong enrichment of electropositive contaminants, namely Ca and Ti, in the oxygen islands. On Pt(110) predosed with Cs, we find that the alkali metal accumulates in the oxygen islands, producing Δϕ ≈ −0.4 eV relative to CO−adlayer. Our experiments suggest that the interpretation of the low WF areas as due to “subsurface oxygen” should be revised and attributed to the local enrichment of electropositive species.
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Energy(all)
- General Energy
- Chemistry(all)
- Physical and Theoretical Chemistry
- Materials Science(all)
- Surfaces, Coatings and Films
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In: Journal of Physical Chemistry C, Vol. 120, No. 47, 18.11.2016, p. 26864-26872.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Revisiting the Origin of Low Work Function Areas in Pattern Forming Reaction Systems
T2 - Electropositive Contaminants or Subsurface Oxygen?
AU - Hesse, Martin
AU - Locatelli, Andrea
AU - Mentes, Tevfik O.
AU - Santos, Benito
AU - Imbihl, Ronald
AU - Günther, Sebastian
N1 - Publisher Copyright: © 2016 American Chemical Society. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2016/11/18
Y1 - 2016/11/18
N2 - In pattern-forming reaction systems, the conversion of macroscopic islands of chemisorbed oxygen into low work function (WF) areas has been attributed to formation of a subsurface oxygen species. We prepare micrometer-sized oxygen islands on Pt(100) and Pt(110) by reaction fronts in catalytic CO oxidation in the 10−6 mbar range. By applying electron microscopy with chemical and structural sensitivity, we characterize their chemical composition upon annealing in vacuum. On Pt(100) we reproduce the previously reported transformation from high to low WF, estimating a relative change Δϕ ≈-0.8 eV with respect to the CO covered surface. We demonstrate that the change in WF is due to a strong enrichment of electropositive contaminants, namely Ca and Ti, in the oxygen islands. On Pt(110) predosed with Cs, we find that the alkali metal accumulates in the oxygen islands, producing Δϕ ≈ −0.4 eV relative to CO−adlayer. Our experiments suggest that the interpretation of the low WF areas as due to “subsurface oxygen” should be revised and attributed to the local enrichment of electropositive species.
AB - In pattern-forming reaction systems, the conversion of macroscopic islands of chemisorbed oxygen into low work function (WF) areas has been attributed to formation of a subsurface oxygen species. We prepare micrometer-sized oxygen islands on Pt(100) and Pt(110) by reaction fronts in catalytic CO oxidation in the 10−6 mbar range. By applying electron microscopy with chemical and structural sensitivity, we characterize their chemical composition upon annealing in vacuum. On Pt(100) we reproduce the previously reported transformation from high to low WF, estimating a relative change Δϕ ≈-0.8 eV with respect to the CO covered surface. We demonstrate that the change in WF is due to a strong enrichment of electropositive contaminants, namely Ca and Ti, in the oxygen islands. On Pt(110) predosed with Cs, we find that the alkali metal accumulates in the oxygen islands, producing Δϕ ≈ −0.4 eV relative to CO−adlayer. Our experiments suggest that the interpretation of the low WF areas as due to “subsurface oxygen” should be revised and attributed to the local enrichment of electropositive species.
UR - http://www.scopus.com/inward/record.url?scp=85025672830&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcc.6b08832
DO - 10.1021/acs.jpcc.6b08832
M3 - Article
AN - SCOPUS:85025672830
VL - 120
SP - 26864
EP - 26872
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 47
ER -