uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Titania Nanoscale Films and Surfaces: Surface Science Investigation of Structure and Properties
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents surface science studies, investigating several aspects of titanium dioxide at the atomic scale. The greater part of this work is devoted to the preparation by chemical vapor deposition (CVD) of titanium(IV) tetraisopropoxide (TTIP) of ultrathin TiO2 or TiOx films on Au(111). Four ordered structures were growth and characterized. It was also demonstrated how the morphology of the film (wetting film vs island) can be tailored. The acquired knowledge about the CVD process was exploited to load nano porous gold with titania, enhancing its catalytic activity. The reactivity towards water adsorption of the titania structures on Au(111) was also investigated. Finally, part of this work concerned the studying of the behavior of water on the stoichiometric rutile TiO2(110) surface, combining the experiments with density-functional theory (DFT) calculations and (kinetic) Monte Carlo simulations. The main experimental techniques used in this work are low-energy electron diffraction (LEED), scanning tunneling microscopy (STM) and photoelectron spectroscopy (PES).

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. , 71 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1154
Keyword [en]
Photoelectron spectroscopy, PES, XPS, scanning tunneling microscopy, STM, titania, titanium oxide, TiO2, Au(111), gold, water, H2O, rutile
National Category
Atom and Molecular Physics and Optics Condensed Matter Physics
Identifiers
URN: urn:nbn:se:uu:diva-224124ISBN: 978-91-554-8969-4 (print)OAI: oai:DiVA.org:uu-224124DiVA: diva2:715366
Public defence
2014-06-13, Polhemsalen 10134, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2014-05-22 Created: 2014-05-05 Last updated: 2014-06-30
List of papers
1. Chemical vapor deposition of ordered TiOx nanostructures on Au(111)
Open this publication in new window or tab >>Chemical vapor deposition of ordered TiOx nanostructures on Au(111)
2013 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 617, 211-217 p.Article in journal (Refereed) Published
Abstract [en]

The deposition of TiOx (x ≤ 2) structures on Au(111) by chemical vapor deposition (CVD) in ultrahigh vacuum (UHV) has been investigated with high-resolution core level photoelectron spectroscopy (PES), low-energy electron diffraction (LEED) and scanning tunnelingmicroscopy (STM). Using titanium tetra-isopropoxide as single source precursor it is possible to form different TiOx phases on the surface after deposition: at low coverages, we observe large two-dimensional (2D) honeycomb-lattice Ti2O3 islands with a (2 × 2) registry with the substrate. Higher coverages are dominated by the formation of three-dimensional (3D) TiO2 structures. The TiO2 structures are atomically well ordered provided that the deposition temperature is high enough (500 °C). The ordered structure exhibits a LEED pattern characteristic for a rectangular surface unit cell. By performing the deposition at different temperatures it is possible to tune the balance between the 2D and 3D phases: Growth at 500 °C significantly favors the formation of 3D TiO2 islands as compared to growth at 200 °C and 300 °C.

National Category
Atom and Molecular Physics and Optics Materials Chemistry Condensed Matter Physics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-212702 (URN)
Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2017-12-06
2. Growth of TiO2(B)(001) on Au(111) by Chemical Vapor Deposition
Open this publication in new window or tab >>Growth of TiO2(B)(001) on Au(111) by Chemical Vapor Deposition
Show others...
2015 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 633, 102-108 p.Article in journal (Refereed) Published
Abstract [en]

This study presents how a TiO2(B) film exposing the (001) face can be grown on Au(111) by chemical vapor deposition. Identification and characterization of the TiO2(B)(001) layer are carried out with low-energy electron diffraction (LEED), synchrotron radiation photoelectron spectroscopy (PES), scanning tunneling microscopy (STM) and X-ray absorption spectroscopy (XAS). Formation of the TiO2(B) film requires a two-step preparation procedure: deposition at 280 °C followed by annealing to 500 °C. This suggests that the interaction between a substrate and an overlayer stabilizes the TiO2(B) film, preventing the formation of thermodynamically more stable rutile islands. The study thus gives insight into how the morphology and the atomic structure of the titania overlayer can be controlled.

Keyword
TiO2, Au(111), CVD, titania, gold
National Category
Condensed Matter Physics Atom and Molecular Physics and Optics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-224091 (URN)10.1016/j.susc.2014.10.011 (DOI)000348336000015 ()
Available from: 2014-05-04 Created: 2014-05-02 Last updated: 2017-12-05Bibliographically approved
3. Structure of a pinwheel-like TiOx single layer phase on Au(111)
Open this publication in new window or tab >>Structure of a pinwheel-like TiOx single layer phase on Au(111)
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-224104 (URN)
Available from: 2014-05-04 Created: 2014-05-04 Last updated: 2014-06-30
4. Controlled modification of nanoporous gold: Chemical vapor deposition of TiO2 in ultrahigh vacuum
Open this publication in new window or tab >>Controlled modification of nanoporous gold: Chemical vapor deposition of TiO2 in ultrahigh vacuum
Show others...
2013 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 282, 439-443 p.Article in journal (Refereed) Published
Abstract [en]

TiO2 has been deposited in the first 400 nm of a nanoporous gold (NPG) structure using metal organic chemical vapor deposition with titanium-tetraisopropoxide as single source precursor in ultra high vacuum. The NPG has been pretreated by ozone to clean and stabilize the structure for deposition. The deposited oxide stabilizes the porous structure, otherwise prone to coarsening at elevated temperatures, up to 300 degrees C. The study combines the controlled sample preparation with a functional test of the prepared catalyst under real conditions in a continuous gas flow reactor. The catalytic activity of the loaded NPG at 60 degrees C for CO oxidation is found to be superior to unloaded as-prepared NPG.

Keyword
Nanoporous gold, Titania, Chemical vapor deposition, Heterogeneous catalysis, Ultrahigh vacuum
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-206545 (URN)10.1016/j.apsusc.2013.05.148 (DOI)000322314800064 ()
Available from: 2013-09-02 Created: 2013-09-02 Last updated: 2017-12-06Bibliographically approved
5. Water adsorption on TiOx thin films grown on Au(111)
Open this publication in new window or tab >>Water adsorption on TiOx thin films grown on Au(111)
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Atom and Molecular Physics and Optics Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-224106 (URN)
Available from: 2014-05-04 Created: 2014-05-04 Last updated: 2014-06-30
6. A Molecular Mechanism for the Water-Hydroxyl Balance during Wetting of TiO2
Open this publication in new window or tab >>A Molecular Mechanism for the Water-Hydroxyl Balance during Wetting of TiO2
Show others...
2013 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 33, 17078-17083 p.Article in journal (Refereed) Published
Abstract [en]

We show that the formation of the wetting layer and the experimentally observed continuous shift of the H2O-OH balance toward molecular water at increasing coverage on a TiO2(110) surface can be rationalized on a molecular level. The mechanism is based on the initial formation of stable hydroxyl pairs, a repulsive interaction between these pairs, and an attractive interaction with respect to water molecules. The experimental data are obtained by synchrotron radiation photoelectron spectroscopy and interpreted with the aid of density functional theory calculations and Monte Carlo simulations.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-208369 (URN)10.1021/jp405208x (DOI)000323593100037 ()
Available from: 2013-09-30 Created: 2013-09-30 Last updated: 2017-12-06Bibliographically approved
7. Kinetics of water adsorption on TiO2(110)
Open this publication in new window or tab >>Kinetics of water adsorption on TiO2(110)
Show others...
(English)Manuscript (preprint) (Other (popular science, discussion, etc.))
National Category
Atom and Molecular Physics and Optics Condensed Matter Physics Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-224107 (URN)
Available from: 2014-05-04 Created: 2014-05-04 Last updated: 2014-06-30

Open Access in DiVA

fulltext(67963 kB)198 downloads
File information
File name FULLTEXT01.pdfFile size 67963 kBChecksum SHA-512
bf50bc50ab07051ad2d6f6416c3d0b252575eedabce606bb2bca406aa8fd0145ee31e4fd3349c02fce8c5605aa7488eb0fb6ccc4fce90d6d12c42a1dade837eb
Type fulltextMimetype application/pdf
Buy this publication >>

Authority records BETA

Ragazzon, Davide

Search in DiVA

By author/editor
Ragazzon, Davide
By organisation
Molecular and condensed matter physics
Atom and Molecular Physics and OpticsCondensed Matter Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 198 downloads
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

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1612 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf