Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Adsorption and decoposition of ethanol on Cu2O(111) and (100)
Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.ORCID-id: 0000-0002-1805-4993
Vise andre og tillknytning
2019 (engelsk)Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, nr 33, s. 20384-20392Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Ethanol dehydrogenation on metal oxides such as Cu2O is an important reaction for the production of renewable energy by fuel cells both via the production of H2 fuel and applied in direct alcohol fuel cells. To better understand this reaction we studied the adsorption, dissociation and desorption of ethanol on Cu2O(111) and (100) surfaces using high-resolution photoelectron spectroscopy (PES), vibrational sum frequency generation spectroscopy (SFG), and temperature programmed desorption (TPD) accompanied by density functional theory (DFT) calculations. On Cu2O(100) the first layer consists primarily of dissociatively adsorbed ethoxy. Second and third layers of ethanol physisorb at low temperature and desorb below 200 K. On the Cu2O(111) surface, adsorption is mixed as ethoxy, ethanol and the products following C-C cleavage, CHx and OCHx, are found in the first layer. Upon heating, products following both C-C and C-O bond breaking are observed on both surfaces and continued heating accentuates the molecular cracking. C-O cleavage occurs more on the (100) surface, whereas on the Cu2O(111) C-C cleavage dominates and occurs at lower temperatures than on the (100) surface. The increased ability of Cu2O(111) to crack ethanol is explained by the varied surface structure including both surface oxygen, electron rich O-vacancies and Cu.

sted, utgiver, år, opplag, sider
2019. Vol. 123, nr 33, s. 20384-20392
HSV kategori
Forskningsprogram
kemisk fysik
Identifikatorer
URN: urn:nbn:se:su:diva-171369DOI: 10.1021/acs.jpcc.9b05394ISI: 000482545700035OAI: oai:DiVA.org:su-171369DiVA, id: diva2:1340718
Tilgjengelig fra: 2019-08-06 Laget: 2019-08-06 Sist oppdatert: 2019-09-16bibliografisk kontrollert
Inngår i avhandling
1. Experimental investigations of model catalytic surface reactions on metal and metal oxide surfaces
Åpne denne publikasjonen i ny fane eller vindu >>Experimental investigations of model catalytic surface reactions on metal and metal oxide surfaces
2019 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

In the development of renewable energies catalysis plays an important role, for example in the production of H2 gas that drives fuel cells, or in the decomposition of annoying by-products of renewable energy production. Most catalysts and catalytic processes currently used in the industry have their roots in macroscopic empirical investigations and trial and error-based optimization. In order to be able to design novel catalytic processes more efficiently, detailed understanding of the catalyst-reactant interaction and the dynamics of the microscopic reaction steps is needed. The present thesis aims to contribute to the fundamental understanding of catalyst reactant systems by means of experiments using model systems in Ultra High Vacuum. For this purpose, several surface science techniques were employed such as vibrational sum-frequency generation (SFG), X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD) and femtochemistry.

In the present thesis the results of three different projects are presented. The first concerns the adsorption and decomposition of naphthalene on Ni(111). Using scanning tunnelling microscopy (STM) and density functional theory (DFT) we identify the adsorption energy and geometry of the naphthalene molecule. Using SFG and TPD we investigate the temperature dependent breakdown of the naphthalene molecule and identify geometrical changes of the adsorbate as an intermediate step in the decomposition reaction. Additionally, we observe poisoning of the surface due to graphene growth using both STM and XPS and explore the possible effect of co-adsorption with oxygen on the reaction pathway and the poisoning of the catalyst.

The second section concerns the adsorption and decomposition of ethanol and methanol on cuprous oxide (Cu2O). Using mainly XPS and SFG we show that ethanol adsorbs dissociatively on Cu2O(100) and (111) and that methanol adsorbs dissociatively on the (100) but molecularly on the (111) surface. Furthermore, we identify intermediate surface species and products of the temperature dependent dehydrogenation of both alcohols and show that the (111) surface is the more effective catalyst for decomposition.

The third section explores the physics of non-thermal excitation methods and discusses CO oxidation on ruthenium (0001) induced by an optical laser and by X-rays from a free electron laser. Based on these femtochemistry experiments we discuss in particular the energy transfer both for direct excitation and for substrate mediated excitations. We show that we were able to control the branching ratios of competing mechanisms and understand the role of non-thermal electrons in the mechanisms of optical laser excitation. Furthermore, we show that it is possible to induce CO oxidation by direct X-ray core hole excitation and can rationalize the relaxation process that leads to CO oxidation.

sted, utgiver, år, opplag, sider
Stockholm: Department of Physics, Stockholm University, 2019. s. 87
HSV kategori
Forskningsprogram
kemisk fysik
Identifikatorer
urn:nbn:se:su:diva-171385 (URN)978-91-7797-706-3 (ISBN)978-91-7797-707-0 (ISBN)
Disputas
2019-09-26, FA31 sal, AlbaNova universitetscentrum, Roslagstullbacken 21, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.

Tilgjengelig fra: 2019-09-03 Laget: 2019-08-13 Sist oppdatert: 2019-08-30bibliografisk kontrollert

Open Access i DiVA

Fulltekst mangler i DiVA

Andre lenker

Forlagets fulltekst

Søk i DiVA

Av forfatter/redaktør
Marks, KessBesharat, ZahraSoldemo, MarkusWeissenrieder, JonasHalldin Stenlid, JoakimÖström, Henrik
Av organisasjonen
I samme tidsskrift
The Journal of Physical Chemistry C

Søk utenfor DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric

doi
urn-nbn
Totalt: 51 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf