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
Fine control of the amount of preferential <001> orientation in DC magnetron sputtered nanocrystalline TiO2 film
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
2014 (English)In: INERA Workshop: Transition Metal Oxide Thin Films-functional Layers in "Smart windows" and Water Splitting Devices. Parallel session of the 18th International School on Condensed Matter Physics / [ed] Prof. DSc Kostadinka Gesheva, Institute of Physics (IOP), 2014, UNSP 012011- p.Conference paper, Published paper (Refereed)
Abstract [en]

Different crystal facets of anatase TiO2 are known to have different chemical reactivity; in particular the {001} facets which truncates the bi-tetrahedral anatase morphology are reported to be more reactive than the usually dominant {101} facets. Anatase TiO2 thin films were deposited by reactive DC magnetron sputtering in Ar/O2 atmosphere and were characterized using Rietveld refined grazing incidence X-ray diffraction, atomic force microscopy and UV/Vis spectroscopy. By varying the partial O2 pressure in the deposition chamber, the degree of orientation of the grains in the film could be systematically varied with preferred <001> orientation changing from random upto 39% as determined by March-Dollase method. The orientation of the films is shown to correlate with their reactivity, as measured by photo-degradation of methylene blue in water solutions. The results have implications for fabrication of purposefully chemically reactive thin TiO2 films prepared by sputtering methods.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2014. UNSP 012011- p.
Series
Journal of Physics Conference Series, ISSN 1742-6588 ; 559
Keyword [en]
anatase, photocatalysis, preferential, orientation, sputtering
National Category
Nano Technology Chemical Process Engineering Inorganic Chemistry Condensed Matter Physics
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
URN: urn:nbn:se:uu:diva-236977DOI: 10.1088/1742-6596/559/1/012011ISI: 000346420600011OAI: oai:DiVA.org:uu-236977DiVA: diva2:766047
Conference
INERA Workshop: Transition Metal Oxide Thin Films-functional Layers in "Smart windows" and Water Splitting Devices. Parallel session of the 18th International School on Condensed Matter Physics, 4–6 September 2014, Varna, Bulgaria
Funder
EU, European Research Council, 267234
Available from: 2014-11-25 Created: 2014-11-25 Last updated: 2016-01-13Bibliographically approved
In thesis
1. Photocatalytic TiO2 thin films for air cleaning: Effect of facet orientation, chemical functionalization, and reaction conditions
Open this publication in new window or tab >>Photocatalytic TiO2 thin films for air cleaning: Effect of facet orientation, chemical functionalization, and reaction conditions
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Poor indoor air quality is a source of adverse health effects. TiO2 coatings deposited on well-illuminated surfaces, such as window panes, can be used to fully mineralize indoor air pollutants by photocatalysis. In such applications it is important to ensure stable photocatalytic activity for a wide range of operating conditions, such as relative humidity and temperature, and to avoid deactivation of the catalyst.

In this thesis photocatalytic removal of the indoor-pollutant acetaldehyde (CH3CHO) on nanostructured TiO2 films is investigated, and in particular it is proposed how such films can be modified and operated for maximum performance. Catalyst deactivation can be reduced by purposefully changing the surface acidity of TiO2 by covalently attaching SO4 to the surface. Moreover, the overall photocatalytic activity on anatase TiO2 films can be improved by increasing the fraction of exposed reactive {001} surfaces, which otherwise are dominated by {101} surfaces.

In the first part of the thesis mode-resolved in-situ FTIR is used to elucidate the reaction kinetics of CH3CHO adsorption and photo-oxidation on the TiO2 and SO4 – modified TiO2 surfaces. Surface concentrations of main products and corresponding reaction rates were determined. Formate is the major reaction product, whose further oxidation limits the complete oxidation to gaseous species, and is responsible for photocatalyst deactivation by site inhibition. The oxidation reaction is characterized by two reaction pathways, which are associated with two types of surface reaction sites. On the sulfate modified TiO2 catalyst fewer intermediates are accumulated, and this catalyst resists deactivation much better than pure TiO2. A hitherto unknown intermediate – surface-bound acetaldehyde dimer with an adsorption band at 1643 cm−1 was discovered, using interplay between FTIR spectroscopy and DFT calculations.

The second part of the thesis treats the effect of increasing the relative abundance of exposed {001} facets on the photocatalytic activity of anatase TiO2 films prepared by DC magnetron sputtering. A positive effect was observed both for liquid-phase photo-oxidation of methylene blue, and for gas-phase photocatalytic removal of CH3CHO. In both cases it was found that the exposed {001} surfaces were an order of magnitude more reactive, compared to the {101} ones. Furthermore, it was found that the reactive films were more resilient towards deactivation, and exhibited almost unchanged activity under varying reaction conditions. Finally, a synergetic effect of SO4 – modification and high fraction of exposed {001} surfaces was found, yielding photocatalysts with sustained high activity.

The results presented here for facet controlled and chemically modified TiO2 films are of interest for applications in the built environment for indoor air purification and as self-cleaning surfaces.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 148 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1307
Keyword
titanium dioxide, photocatalysis, thin films, surface functionallization, acetaldehyde, indoor air cleaning, sputter deposition, crystallographic modifications, preferential orientation, self-cleaning surfaces
National Category
Chemical Engineering Materials Engineering Nano Technology Theoretical Chemistry Inorganic Chemistry
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-265056 (URN)978-91-554-9387-5 (ISBN)
Public defence
2015-12-11, Polhemssalen, Lägerhyddsv. 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Projects
GRINDOOR
Funder
EU, European Research Council, ERC Grant Agreement No. 267234 (“GRINDOOR”)
Available from: 2015-11-19 Created: 2015-10-21 Last updated: 2016-01-13

Open Access in DiVA

fulltext(1183 kB)258 downloads
File information
File name FULLTEXT01.pdfFile size 1183 kBChecksum SHA-512
47ef1960a93ac8d0e45779d269ed01d434522f71921cc4f87c208b3b0df769c97e151e035f26a653751ad1c262edb4c1d7434795afe7a4ed0529401b806ef3c7
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Authority records BETA

Stefanov, BozhidarGranqvist, Claes-GöranÖsterlund, Lars

Search in DiVA

By author/editor
Stefanov, BozhidarGranqvist, Claes-GöranÖsterlund, Lars
By organisation
Solid State Physics
Nano TechnologyChemical Process EngineeringInorganic ChemistryCondensed Matter Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 258 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

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 874 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