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Mattsson, AndreasORCID iD iconorcid.org/12751850400
Publications (10 of 32) Show all publications
Johansson, M. B., Mattsson, A., Lindquist, S.-E., Niklasson, G. A. & Österlund, L. (2017). The Importance of Oxygen Vacancies in Nanocrystalline WO3−x ThinFilms Prepared by DC Magnetron Sputtering for Achieving High Photoelectrochemical Efficiency. The Journal of Physical Chemistry C, 121(13), 7412-7420
Open this publication in new window or tab >>The Importance of Oxygen Vacancies in Nanocrystalline WO3−x ThinFilms Prepared by DC Magnetron Sputtering for Achieving High Photoelectrochemical Efficiency
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2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 13, p. 7412-7420Article in journal (Refereed) Published
Abstract [en]

The photoelectrochemical properties of tungsten oxide thinfilms with different stoichiometry (WO3−x) and thickness were investigated.The films were sputtered in O2/Ar gas (ratio 0.43) on glass substrates coatedwith fluorine-doped tin dioxide at two sputter pressures, Ptot = 10 and 30mTorr, yielding O/W ratios of the films, averaged over three samples, of 2.995and 2.999 (x ∼ 0.005 and x ∼ 0.001), respectively. The films were characterizedby X-ray diffraction, scanning electron microscopy, and spectrophotometry.The 10 mTorr samples showed large absorption in the near-infrared (NIR)range, whereas the 30 mTorr samples had a small absorption in this region. Theconcentration of oxygen vacancy band gap states was estimated from cyclicvoltammetry and was found to correlate with the optical absorption in the NIRregion. The incident photon to current efficiency for illumination from theelectrolyte side (IPCEEE) and substrate electrode side (IPCESE) showed higherefficiency for the more stoichiometric films, indicating that oxygen vacancies in the band gap act as recombination centers.Surprisingly high values of IPCEEE and IPCESE were found, and it was concluded that efficient charge separation and transporttake place almost throughout the entire film even for film electrodes as thick as 2 μm. Analysis of the spectral distribution of thephotoresponse (action spectra) using an extended Gärtner−Butler model to calculate the IPCE for front-side and back-sideillumination was performed and showed that the diffusion length is large, of the order of the depletion layer thickness.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
Keywords
Photoelectrochemistry, WO3, Oxygen vacancy, thin films
National Category
Physical Chemistry Engineering and Technology
Research subject
Chemistry with specialization in Physical Chemistry; Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-319249 (URN)10.1021/acs.jpcc.7b00856 (DOI)000398881800040 ()
Funder
Swedish Research Council, VR-2010-3514Swedish Research Council, VR-2011-3940
Available from: 2017-04-02 Created: 2017-04-02 Last updated: 2018-08-30Bibliographically approved
Mattsson, A. & Österlund, L. (2016). Infrared Reflection-Absorption Spectroscopy Study of the Interaction between O2 and Formic Acid on Rutile TiO2 (110) Surfaces. In: : . Paper presented at 2016 MRS spring meeting & exhibit.
Open this publication in new window or tab >>Infrared Reflection-Absorption Spectroscopy Study of the Interaction between O2 and Formic Acid on Rutile TiO2 (110) Surfaces
2016 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Formic acid adsorption on rutile TiO2(110) single crystals exposed to different oxygen partial pressures have been investigated with infrared reflection-absorption spectroscopy (IRRAS) employing p- and s-polarized light incident along the [001] crystal direction at a temperatures between 273K and 303K. IRRAS spectra, prior to oxygen exposure, shows that formic acid dissociates upon adsorption and binds to the surface as bridging formate species with the symmetric νs(OCO) and asymmetric νas(OCO) peak at 1360 and 1531 cm-1, respectively. A new asymmetric νas(OCO) band at 1517 cm-1develops in the presence of O2, which is correlated with the O2 partial pressure, whereas no changes is seen in the symmetric νs(OCO) band. At low O2 pressures(<1 ×10-7mbar), this band is not detectable within 3 h of O2 exposure. At higher O2pressures, 5 ×10-7 mbar, the band starts to develop, and at 1 ×10-6 mbar, a pronounced band develops after 30 min exposure. The O2 induced band at 1517 cm-1 does not disappear as the O2 gas is removed, suggesting that a stable chemical modification of adsorbed formate molecules. No changes were observed in the s-polarized IRRAS spectra with O2 exposure, showing that there is no rotation of the formate molecules in the plane of the surface. The appearance of the new νas(OCO) band are consistent with a model where O2 dissociated to form O adatoms bonded to the Ti5c atoms, which interact with bridging formate molecules bonded along the [001] direction. The relationship between the oxygen partial pressure and the formation of this new band is due to the increased larger interaction between the surface and the oxygen with increase pressure or an increased oxygenation of formate. Our results provide new insight into the interaction between O2and TiO2surfaceat elevated pressures relevant for practical applications.

National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-283107 (URN)
External cooperation:
Conference
2016 MRS spring meeting & exhibit
Funder
Swedish Research Council, 2015-04757
Available from: 2016-04-11 Created: 2016-04-11 Last updated: 2016-08-30Bibliographically approved
Stefanov, B. I., Lebrun, D., Mattsson, A., Granqvist, C. G. & Österlund, L. (2015). Demonstrating Online Monitoring of Air Pollutant Photodegradation in a 3D Printed Gas-Phase Photocatalysis Reactor. Journal of Chemical Education, 92(4), 678-682
Open this publication in new window or tab >>Demonstrating Online Monitoring of Air Pollutant Photodegradation in a 3D Printed Gas-Phase Photocatalysis Reactor
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2015 (English)In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 92, no 4, p. 678-682Article in journal (Refereed) Published
Abstract [en]

We present a demonstration of online monitoring of gas-phase photocatalytic reactions. A cotton cloth impregnated with commercial titanium dioxide nanoparticles is used as a photocatalytic filter to clean air contaminated with a model pollutant. A fan forces air through the filter while it is irradiated by UV diodes. The concentration of the air pollutant is measured online by an inexpensive, commercially available semiconductor air quality sensor. The structural parts of the reactor were 3D printed in polylactide bioplastic. We provide all schematics, 3D printed model parts, hardware, firmware, and computer code of the reactor and control units. The device can be used for interactive learning of both gas phase photocatalysis and gas sensing, as well as in student laboratory classes for measuring air pollutants and their photodegradation. The experimental setup can also form the basis for a project work for chemical engineering university students, and it can be employed as a building block for development of other gas phase chemical reaction demonstrations.

Keywords
Chemical Engineering, General Public, Photocatalysis, Gases, Photochemistry, Reactions, Nanotechnology, Laboratory Equipment/Apparatus
National Category
Physical Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-253071 (URN)10.1021/ed500604e (DOI)000353368000017 ()
Available from: 2015-06-11 Created: 2015-05-20 Last updated: 2017-12-04Bibliographically approved
Wäckelgård, E., Mattsson, A., Bartali, R., Gerosa, R., Gloria, G., Gustavsson, F., . . . Rivolta, B. (2015). Development of W–SiO2 and Nb–TiO2 solar absorber coatings for combined heat and power systems at intermediate operation temperatures. Solar Energy Materials and Solar Cells, 133, 180-193
Open this publication in new window or tab >>Development of W–SiO2 and Nb–TiO2 solar absorber coatings for combined heat and power systems at intermediate operation temperatures
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2015 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 133, p. 180-193Article in journal (Refereed) Published
Abstract [en]

Two new absorber coatings for mid-temperature operation (300–350 1C) in collectors for solar thermal electricity plants are presented in this study. The absorbers consist of two cermet layers of either W–SiO2 or Nb–TiO2, deposited on a molybdenum infrared reflector and coated with an antireflection layer of silicon oxide. The optimization of the optical performance was made in two steps. First, the layer structure was optimized in model calculations. The optical constants used in this modelling were derived directly from sputtered films of the cermet constituents using reflectance and transmittance measure- ments. The absorber coatings were then sputter-deposited using parameters from the modelling. The results show good agreement between modelled and sputtered optical performance evaluated as solar absorptance and thermal emittance at 350 1C. The optimal values reached for W–SiO2 was 0.91 in combination with 0.08 and 0.93 in combination with 0.09 for Nb–TiO2. The materials characterization from XRD, AES and TEM shows that the composite coatings contain nano-metal inclusions, meaning that they are cermet coatings. Scratch tests show that the coatings adhere well to the substrate of stainless steel. Temperature testing at 350 1C in vacuum for up to 1500 h shows that both coatings are stable under such conditions. Only a slight change occurs during the first 72 h that decreases the emittance but does not change the solar absorptance. ERDA confirms that there is no detectable level of ion migration between layers, only a small decrease in hydrogen content was observed, which indicates outgassing.

National Category
Other Engineering and Technologies
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-239313 (URN)10.1016/j.solmat.2014.10.022 (DOI)000348015100027 ()
Projects
Digespo project
Funder
EU, FP7, Seventh Framework Programme
Available from: 2014-12-22 Created: 2014-12-22 Last updated: 2017-12-05Bibliographically approved
Henych, J., Stengl, V., Mattsson, A. & Österlund, L. (2015). In Situ FTIR Spectroscopy Study of the Photodegradation of Acetaldehyde and azo Dye Photobleaching on Bismuth-Modified TiO2. Photochemistry and Photobiology, 91(1), 48-58
Open this publication in new window or tab >>In Situ FTIR Spectroscopy Study of the Photodegradation of Acetaldehyde and azo Dye Photobleaching on Bismuth-Modified TiO2
2015 (English)In: Photochemistry and Photobiology, ISSN 0031-8655, E-ISSN 1751-1097, Vol. 91, no 1, p. 48-58Article in journal (Refereed) Published
Abstract [en]

The photocatalytic properties of bismuth-modified titania were studied by photobleaching of two aqueous azo dyes solutions (Reactive Black 5 and Acid Orange 7), and by photoinduced decomposition (PID) of acetaldehyde using in situ FTIR spectroscopy. Low bismuth doping concentrations up to 3 at.% is shown to lead to an increased photobleaching rate of both azo dyes solutions. Too high Bi dopant concentrations lead to less developed crystallite nanoparticles and exhibit weaker adsorption capacity. Bismuth doping altered the adsorption kinetics of acetaldehyde resulting in different surface products, and a modified photocatalytic reaction pathway was inferred.

National Category
Physical Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-246674 (URN)10.1111/php.12374 (DOI)000348442600006 ()25349041 (PubMedID)
Available from: 2015-03-18 Created: 2015-03-09 Last updated: 2017-12-04Bibliographically approved
Hu, S., Wang, Z., Mattsson, A., Österlund, L. & Hermansson, K. (2015). Simulation of IRRAS Spectra for Molecules on Oxide Surfaces: CO on TiO2(110). The Journal of Physical Chemistry C, 119(10), 5403-5411
Open this publication in new window or tab >>Simulation of IRRAS Spectra for Molecules on Oxide Surfaces: CO on TiO2(110)
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2015 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 10, p. 5403-5411Article in journal (Refereed) Published
Abstract [en]

We explore a method that cart sirriulate infrared refiection absotption spectroscopy (IRRAS) spectra for molecules adsjorlied on semiconductor surfaces. The method rakes it possible to directly correlate experimental spectra with possible adsorbate structures. Our example in thiS paper is CO adsoihed on rutile TiO2(110). We present simulated IRRAS spectra for coverages in the range from 0.125 to 1.5 Monolayer (ML) An explanation is provided. for the apparent inconsistency in the literature concerning the tilting geometry of 1 ML CO on this surface. We find that a tilted structure (which is also the lowest-energy configuration) generates IRRAS spectra in excellent agreement with the experimental spectra. Furthermore, we predict the adsorption structure for 1.5 ML CO coverage over TiO2 (110), which consists of very weakly bound CO molecules on top of the monolayer. In all cases, our simulation method) which is based On density functioual theory (PFT) vibrational calculations, produces s- and p-polarized IRRAS spectra in excellent agreement with the experimental spectra.

National Category
Physical Chemistry Other Engineering and Technologies
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-251804 (URN)10.1021/jp5094096 (DOI)000351189100017 ()
Available from: 2015-04-28 Created: 2015-04-24 Last updated: 2017-12-04
Mattsson, A., Hu, S., Hermansson, K. & Österlund, L. (2014). Adsorbtion and photodecomposition of formic acid on stoichiometric and defective rutile TiO2 (110) surfaces. Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, 32(061402-1)
Open this publication in new window or tab >>Adsorbtion and photodecomposition of formic acid on stoichiometric and defective rutile TiO2 (110) surfaces
2014 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 32, no 061402-1Article in journal (Refereed) Published
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-286500 (URN)
Available from: 2016-04-20 Created: 2016-04-20 Last updated: 2017-11-30
Mattsson, A., Hu, S., Hermansson, K. & Österlund, L. (2014). Adsorption of formic acid on rutile TiO2 (110) revisited: An infrared reflection-absorption spectroscopy and density functional theory study. Journal of Chemical Physics, 140(3), 034705
Open this publication in new window or tab >>Adsorption of formic acid on rutile TiO2 (110) revisited: An infrared reflection-absorption spectroscopy and density functional theory study
2014 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 140, no 3, p. 034705-Article in journal (Refereed) Published
Abstract [en]

Formic acid (HCOOH) adsorption on rutile TiO2 (110) has been studied by s- and p-polarized infrared reflection-absorption spectroscopy (IRRAS) and spin-polarized density functional theory together with Hubbard U contributions (DFT+U) calculations. To compare with IRRAS spectra, the results from the DFT+U calculations were used to simulate IR spectra by employing a three-layer model, where the adsorbate layer was modelled using Lorentz oscillators with calculated dielectric constants. To account for the experimental observations, four possible formate adsorption geometries were calculated, describing both the perfect (110) surface, and surfaces with defects; either O vacancies or hydroxyls. The majority species seen in IRRAS was confirmed to be the bridging bidentate formate species with associated symmetric and asymmetric frequencies of the nu(OCO) modes measured to be at 1359 cm(-1) and 1534 cm(-1), respectively. The in-plane delta(C-H) wagging mode of this species couples to both the tangential and the normal component of the incident p-polarized light, which results in absorption and emission bands at 1374 cm(-1) and 1388 cm(-1). IRRAS spectra measured on surfaces prepared to be either reduced, stoichiometric, or to contain surplus O adatoms, were found to be very similar. By comparisons with computed spectra, it is proposed that in our experiments, formate binds as a minority species to an in-plane Ti-5c atom and a hydroxyl, rather than to O vacancy sites, the latter to a large extent being healed even at our UHV conditions. Excellent agreement between calculated and experimental IRRAS spectra is obtained. The results emphasize the importance of protonation and reactive surface hydroxyls - even under UHV conditions - as reactive sites in e. g., catalytic applications. (C) 2014 AIP Publishing LLC.

National Category
Natural Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-220815 (URN)10.1063/1.4855176 (DOI)000330614400051 ()
Available from: 2014-03-21 Created: 2014-03-20 Last updated: 2017-12-05Bibliographically approved
Stefanov, B., Lebrun, D., Mattsson, A., Granqvist, C. G. & Österlund, L. (2014). Demonstration of a 3D printed gas-phase photocatalysis reactor and its use for on-line monitoring of degradation of air pollutants.. Journal of Chemical Education
Open this publication in new window or tab >>Demonstration of a 3D printed gas-phase photocatalysis reactor and its use for on-line monitoring of degradation of air pollutants.
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2014 (English)In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328Article in journal (Refereed) Published
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-234925 (URN)
Projects
EU GRINDOOR
Funder
EU, FP7, Seventh Framework Programme, 267234
Available from: 2014-10-27 Created: 2014-10-27 Last updated: 2017-12-05
Wäckelgård, E., Mattsson, A., Bartali, R., Gerosa, R., Gottardi, G., Gustavsson, F., . . . Rivolta, B. (2014). Development of W-SiO2 and Nb-TiO2 solar absorber coatings for combined heat and power systems at intermediate operation temperatures. Solar Energy Materials and Solar Cells, 133
Open this publication in new window or tab >>Development of W-SiO2 and Nb-TiO2 solar absorber coatings for combined heat and power systems at intermediate operation temperatures
Show others...
2014 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 133Article in journal (Refereed) Published
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-286696 (URN)
Available from: 2016-04-21 Created: 2016-04-21 Last updated: 2017-11-30
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/12751850400

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