Change search
ReferencesLink to record
Permanent link

Direct link
Stability of Pt-Modified Cu(111) in the Presence of Oxygen and Its Implication on the Overall Electronic Structure
Stockholm University, Faculty of Science, Department of Physics.
Show others and affiliations
2013 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 32, 16371-16380 p.Article in journal (Refereed) Published
Abstract [en]

The electronic structure and stability of Cu(111)-hosted Pt overlayers with and without the presence of atomic oxygen have been studied by means of core-level spectroscopy and density functional theory (DFT). Because of lattice mismatch, Pt(111) overlayers grown on Cu(111) are compressively strained, and hard X-ray photoelectron spectroscopy together with Pt L-3-edge X-ray absorption spectroscopy (XAS) reveals a pronounced downshift of the Pt d-band owing to the increased overlap of the d-orbitals, an effect also reproduced theoretically. Exposure to oxygen severely alters the surface composition; the O-Cu binding energy largely exceeds that of O-Pt, and DFT calculations predict surface segregation of Cu atoms. Comparing the adsorbate electronic structure for O on unstrained Pt(111) with that of O on Pt-modified Cu(111) using O K-edge XAS and X-ray emission spectroscopy salient differences are observed and calculations show that Cu-segregation to the topmost layer is required to reproduce the measured spectra. It is proposed that O is binding in a hollow site constituted by at least two Cu atoms and that up to 75% of the Pt atoms migrate below the surface.

Place, publisher, year, edition, pages
2013. Vol. 117, no 32, 16371-16380 p.
National Category
Physical Chemistry Materials Chemistry Nano Technology
URN: urn:nbn:se:su:diva-93562DOI: 10.1021/jp400486rISI: 000323301100012OAI: diva2:647558


Funding agencies:

Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering  DE-AC02-76SF00515;  Swedish Research Council (VR);   Ministry of Education, Culture, Sports, Science and Technology  2009B1751/BL-47XU;

 U.S. Department of Energy  DE-AC02-76SF00515;  Alexander von Humboldt Foundation  

Available from: 2013-09-11 Created: 2013-09-10 Last updated: 2014-04-01Bibliographically approved
In thesis
1. Surface reactions and chemical bonding in heterogeneous catalysis
Open this publication in new window or tab >>Surface reactions and chemical bonding in heterogeneous catalysis
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis summarizes studies which focus on addressing, using both theoretical and experimental methods, fundamental questions about surface phenomena, such as chemical reactions and bonding, related to processes in heterogeneous catalysis. The main focus is on the theoretical approach and this aspect of the results. The included articles are collected into three categories of which the first contains detailed studies of model systems in heterogeneous catalysis. For example, the trimerization of acetylene adsorbed on Cu(110) is measured using vibrational spectroscopy and modeled within the framework of Density Functional Theory (DFT) and quantitative agreement of the reaction barriers is obtained. In the second category, aspects of fuel cell catalysis are discussed. O2 dissociation is rate-limiting for the reduction of oxygen (ORR) under certain conditions and we find that adsorbate-adsorbate interactions are decisive when modeling this reaction step. Oxidation of Pt(111) (Pt is the electrocatalyst), which may alter the overall activity of the catalyst, is found to start via a PtO-like surface oxide while formation of α-PtO2 trilayers precedes bulk oxidation. When considering alternative catalyst materials for the ORR, their stability needs to be investigated in detail under realistic conditions. The Pt/Cu(111) skin alloy offers a promising candidate but segregation of Cu atoms to the surface is induced by O adsorption. This is confirmed by modeling oxygen x-ray emission (XES) and absorption spectra of the segregated system and near-perfect agreement with experiment is obtained when vibrational interference effects are included in the computed XES. The last category shows results from femtosecond laser measurements of processes involving CO on Ru(0001). Using free-electron x-ray laser experiments a precursor state to desorption is detected and also found in simulations if van der Waals effects are included. Resonant XES can be used to distinguish two different species of CO on the surface; vibrationally hot, chemisorbed CO and CO in the precursor state. Laser-induced CO oxidation on Ru(0001) is modeled and three competing mechanisms are found. Kinetic modeling reproduces the experiment qualitatively.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2014. 66 p.
National Category
Physical Sciences
Research subject
Chemical Physics
urn:nbn:se:su:diva-102323 (URN)978-91-7447-893-8 (ISBN)
Public defence
2014-05-12, sal FP41, AlbaNova universitetscentrum, Roslagstullsbacken 33, Stockholm, 13:00 (English)

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 8: Manuscript.

Available from: 2014-04-16 Created: 2014-04-01 Last updated: 2014-04-22Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Öberg, HenrikNilsson, AndersPettersson, Lars G.M.
By organisation
Department of Physics
In the same journal
The Journal of Physical Chemistry C
Physical ChemistryMaterials ChemistryNano Technology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 42 hits
ReferencesLink to record
Permanent link

Direct link