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Lindquist, Sten-Eric
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Publications (10 of 38) 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
Keyword
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: 2017-05-15Bibliographically approved
Li, M., Zhang, J., Gao, H., Li, F., Lindquist, S.-E., Wu, N. & Wang, R. (2016). Microsized BiOCl Square Nanosheets as Ultraviolet Photodetectors and Photocatalysts. ACS Applied Materials and Interfaces, 8(10), 6662-6668.
Open this publication in new window or tab >>Microsized BiOCl Square Nanosheets as Ultraviolet Photodetectors and Photocatalysts
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2016 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 10, p. 6662-6668Article in journal (Refereed) Published
Abstract [en]

BiOCl microstructures that include microspheres stacked by nanosheet and microsized square nanosheets, with a large lateral size of 3-5 mu m and a thickness of 35 nm (the side length/thickness ratio is similar to 100), are synthesized by a solvothermal method with the assistance of polyvinylpyrrolidone. The exposed face of the large square nanosheet is {001} facet. The BiOCl microstructures show good photocatalytic activity toward decomposition of Rhodamine B under ultraviolet-visible light irradiation. Moreover, individual microsized BiOCl square nanosheets are employed as the building block for construction of an ultraviolet photodetector. Because of its large size, thin thickness, and high surface-to-volume ratio, a BiOCl nanosheet shows high sensitivity and fast transient response to ultraviolet light in the spectral range 200-380 nm.

Keyword
BiOCl, ultraviolet photodetector, photocatalysis, optoelectronics, solvothermal
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-286662 (URN)10.1021/acsami.6b00042 (DOI)000372479300043 ()26913647 (PubMedID)
Available from: 2016-04-27 Created: 2016-04-21 Last updated: 2017-11-30Bibliographically approved
Ding, B., Qian, H., Han, C., Zhang, J., Lindquist, S.-E., Wei, B. & Tang, Z. (2014). Oxygen Vacancy Effect on Photoluminescence Properties of Self-Activated Yttrium Tungstate. The Journal of Physical Chemistry C, 118(44), 25633-25642.
Open this publication in new window or tab >>Oxygen Vacancy Effect on Photoluminescence Properties of Self-Activated Yttrium Tungstate
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2014 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 44, p. 25633-25642Article in journal (Refereed) Published
Abstract [en]

A series of single-phase yttrium tungstate powders were synthesized through solid-state reaction under air or argon atmosphere. All powders showed broad band emission in the visible light region, and the argon-calcined samples presented strong near-infrared luminescence. Moreover, the long-wave excitation bands peaking at 340, 378, 380, 490, and 523 nm depended critically on the calcination atmosphere and temperature. The emergence of these new excitation bands was ascribed to different oxygen vacancy concentrations with the analysis of the first-principle calculation, Raman and X-ray absorption fine structure spectra. The oxygen vacancies caused the reduction of the average coordination number of tungsten, and the position of the localized energy band changed with the oxygen vacancy concentration. Finally, a schematic photoluminescence excitation model was proposed via anion and cation charge transfer. The obtained results promise to be very useful in interpreting self-activated tungstate luminescence mechanism. They can also serve as guide line for tuning the luminescence performance of yttrium tungstate and related materials.

National Category
Chemical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-239365 (URN)10.1021/jp505513c (DOI)000344579300038 ()
Available from: 2014-12-29 Created: 2014-12-22 Last updated: 2017-12-05Bibliographically approved
Lindquist, S.-E. (2013). Wired Enzyme Electrodes: A Retroperspective Story about an Exciting Time at University of Texas at Austin and Its Impact on My Scientific Career. ChemPhysChem, 14(10), 2081-2088.
Open this publication in new window or tab >>Wired Enzyme Electrodes: A Retroperspective Story about an Exciting Time at University of Texas at Austin and Its Impact on My Scientific Career
2013 (English)In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 14, no 10, p. 2081-2088Article in journal (Refereed) Published
Abstract [en]

The present paper features an exciting time in the late 1980s when I, as a visiting scientist, had the privilege to participate in the early and very exciting development of the in vivo redox-polymer-wired glucose sensor in Professor Adam Heller's laboratory at the Department of Chemical Engineering at University of Texas at Austin. This story is followed by an overview of the research my visit initiated at Uppsala University. In collaboration with Swedish colleagues, we explored a few of the many possibilities to form new biosensors by utilizing Prof. Heller's concept of cross-linked redox-polymer/redox-enzyme electrodes.

Keyword
cellobiose dehydrogenase, enzymes, glucose, redox polymers, sensors
National Category
Natural Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-208668 (URN)10.1002/cphc.201300043 (DOI)000322236400012 ()
Available from: 2013-10-07 Created: 2013-10-07 Last updated: 2017-12-06Bibliographically approved
Hinkley, J. T., O'Brien, J. A., Fell, C. J. & Lindquist, S.-E. (2011). Prospects for solar only operation of the hybrid sulphur cycle for hydrogen production. International journal of hydrogen energy, 36(18), 11596-11603.
Open this publication in new window or tab >>Prospects for solar only operation of the hybrid sulphur cycle for hydrogen production
2011 (English)In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 36, no 18, p. 11596-11603Article in journal (Refereed) Published
Abstract [en]

The hybrid sulphur process is one of the most promising thermochemical water splitting cycles for large scale hydrogen production. While the process includes an electrolysis step, the use of sulphur dioxide in the electrolyser significantly reduces the electrical demand compared to conventional alkaline electrolysis. Solar operation of the cycle with zero emissions is possible if the electricity for the electrolyser and the high temperature thermal energy to complete the cycle are provided by solar technologies. This paper explores the possible use of photovoltaics (PV) to supply the electrical demand and examines a number of configurations. Production costs are determined for several scenarios and compared with base cases using conventional technologies. The hybrid sulphur cycle has promise in the medium term as a viable zero carbon production process if PV power is used to supply the electrolyser. However, the viability of this process is dependent on a market for hydrogen and a significant reduction in PV costs to around $1/W(p).

Keyword
Hydrogen production, Hybrid sulphur cycle, Thermochemical cycles, Electrolysis, Solar cells
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-159793 (URN)10.1016/j.ijhydene.2011.06.048 (DOI)000294982800012 ()
Available from: 2011-10-10 Created: 2011-10-10 Last updated: 2017-12-08Bibliographically approved
Waita, S. M., Aduda, B. O., Mwabora, J. M., Granqvist, C.-G., Lindquist, S.-E., Niklasson, G. A., . . . Boschloo, G. K. (2007). Electron Transport and Recombination in Dye Sensitized Solar Cells Fabricated from Obliquely Sputter Deposited and Thermally Annealed TiO2 Films. Journal of Electroanalytical Chemistry, 605(2), 151-156.
Open this publication in new window or tab >>Electron Transport and Recombination in Dye Sensitized Solar Cells Fabricated from Obliquely Sputter Deposited and Thermally Annealed TiO2 Films
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2007 (English)In: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 605, no 2, p. 151-156Article in journal (Refereed) Published
Abstract [en]

Dye sensitized solar cells based on annealed titanium dioxide films prepared by oblique reactive DC magnetron sputtering have been investigated in detail. Electron transport and recombination were studied using intensity-modulated photocurrent and photovoltage spectroscopy. Electron transport time as well as lifetime were found to increase upon lowering of the light intensity and to increase upon increasing the thickness of the TiO2 film. The properties are very similar to those observed for solar cells based on colloidal TiO2 films despite the morphologies being very different. In all cases, films are composed of a porous assembly of TiO2 nanocrystals. Grain boundaries with associated trap and/or energy barriers may explain the observed transport properties.

Keyword
Nanostructured TiO2, Mesoporous materials, Reactive sputtering, Electron trapping
National Category
Chemical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-14459 (URN)10.1016/j.jelechem.2007.04.001 (DOI)000248167500009 ()
Available from: 2011-09-21 Created: 2008-01-30 Last updated: 2017-12-11Bibliographically approved
Romualdo Torres, G., Lindgren, T., Lu, J., Granqvist, C.-G. & Lindquist, S.-E. (2004). Photoelectrochemical Study of Nitrogen-Doped Titanium Dioxide for Water Oxidation. Journal of Physical Chemistry B, 108(19), 5995-6003.
Open this publication in new window or tab >>Photoelectrochemical Study of Nitrogen-Doped Titanium Dioxide for Water Oxidation
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2004 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, no 19, p. 5995-6003Article in journal (Refereed) Published
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-66739 (URN)
Available from: 2007-04-25 Created: 2007-04-25 Last updated: 2017-11-28Bibliographically approved
Lindgren, T., Lu, J., Hoel, A., Granqvist, C.-G., Remualdo Torres, G. & Lindquist, S.-E. (2004). Photoelectrochemical study of sputtered nitrogen-doped titanium dioxide thin films in aqueous electrolyte. Solar Energy Materials and Solar Cells, 84(1-4), 145-157.
Open this publication in new window or tab >>Photoelectrochemical study of sputtered nitrogen-doped titanium dioxide thin films in aqueous electrolyte
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2004 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 84, no 1-4, p. 145-157Article in journal (Refereed) Published
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-68748 (URN)
Available from: 2007-04-25 Created: 2007-04-25 Last updated: 2017-11-21Bibliographically approved
Mwabora, J. M., Lindgren, T., Avendaño, E., Jaramillo, T. F., Lu, J., Lindquist, S.-E. & Granqvist, C.-G. (2004). Structure, Composition and Morphology of Photoelectrochemically Active TiO2-xNx Thin Films Deposited by Reactive DC Magnetron Sputtering. Journal of Physical Chemistry B, 108(52), 20193-20198.
Open this publication in new window or tab >>Structure, Composition and Morphology of Photoelectrochemically Active TiO2-xNx Thin Films Deposited by Reactive DC Magnetron Sputtering
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2004 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, no 52, p. 20193-20198Article in journal (Refereed) Published
Abstract [en]

Films of nitrogen-doped TiO2 were made by reactive DC magnetron sputtering in a mixture of argon, oxygen, and nitrogen. The nitrogen gas ratio Φ was varied in the 0 < Φ < 0.025 range during the depositions, resulting in TiO2-xNx films with 0 ≤ x ≤ 0.022 as determined by X-ray photoelectron spectroscopy. Structural and morphological properties of the films were investigated by X-ray diffraction, atomic force microscopy, and scanning and transmission electron microscopy. Films prepared without nitrogen had a rutile structure, while the nitrogen-doped films were either rutile or anatase depending on Φ being below or above ∼0.007. Deposition rate, effective grain size, root-mean-square roughness, morphology, and optical absorption were also found to depend on Φ. The films were photoelectrochemically active, as reported in an earlier papers of ours [J. Phys. Chem. B 2003, 107, 5709-5716 and J. Phys. Chem. B 2004, 108, 5995-6003].

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-91433 (URN)10.1021/jp0368987 (DOI)
Available from: 2004-02-26 Created: 2004-02-26 Last updated: 2017-12-14Bibliographically approved
Lindgren, T., Mwabora, J. M., Avendaño, E., Jonsson, J., Hoel, A., Granqvist, C.-G. & Lindquist, S.-E. (2003). Photoelectrochemical and Optical Properties of Nitrogen Doped Titanium Dioxide Films Prepared by Reactive DC Magnetron Sputtering. Journal of Physical Chemistry B, 107, 5709-5716.
Open this publication in new window or tab >>Photoelectrochemical and Optical Properties of Nitrogen Doped Titanium Dioxide Films Prepared by Reactive DC Magnetron Sputtering
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2003 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 107, p. 5709-5716Article in journal (Refereed) Published
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-46476 (URN)
Available from: 2007-04-17 Created: 2007-04-17 Last updated: 2017-12-05Bibliographically approved
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