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  • 1.
    Andersson, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Stocklassa, Jesper
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Control Systems For Gas-Expanded Liquids In Microreactors2017Conference paper (Refereed)
  • 2.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteriesManuscript (preprint) (Other academic)
  • 3.
    Asfaw, Habtom
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteriesManuscript (preprint) (Other academic)
  • 4.
    Calmanovici Pacoste, Laura
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Boman, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Ardakani, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Degerman, Martina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Kammarbo, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Näslund, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Processdesign av emulsionsberedningssystem2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    At the request of Fresenius Kabi an emulsion preparation system was designed with a maximum production capacity of  15 L and minimum of 3 L emulsion. The system was required to consist of one oil-tank, one pre-emulsion tank, two storage tanks and one homogenizer. The storage tanks were positioned on a movable carriage on the left side of the homogenizer and the pre-emulsion tank and oil tank was placed on a separate frame on the right side of the homogenizer. All tanks were equipped with individual temperature control and a stand-alone parallel cleaning system was designed.

    The system also had to be optimized for the specific process and extensive calculations were done.  The emulsion system was designed using CAD-software and produced a detailed 3D-model. The tanks were designed from scratch and all other parts of the system consist of standardized components readily available. A list of the components in the system with manufacturer article number of all components was also produced. Actual drawings for the tanks were also made. The 3D-model and the list of components provide a good base for future construction of the system.

  • 5.
    Carlsson, P A
    et al.
    Chalmers University of Technology.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Thormahlen, P
    Chalmers University of Technology.
    Palmqvist, A E C
    Chalmers University of Technology.
    Fridell, E
    Chalmers University of Technology.
    Jansson, J
    Chalmers University of Technology.
    Skoglundh, M
    Chalmers University of Technology.
    A transient in situ FTIR and XANES study of CO oxidation over Pt/Al2O3 catalysts2004In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 226, no 2, p. 422-434Article in journal (Refereed)
    Abstract [en]

    We report experimental results for the oxidation of CO over supported Pt/Al2O3 catalysts operating in oxygen excess at atmospheric pressure. To study the reaction kinetics under transient conditions we have employed step changes of the O-2 concentration by intermittently switching off the O-2 supply at various temperatures ranging from 523 to 623 K. Detailed in situ FTIR and XANES data for CO coverage and the chemical state of Pt, respectively, are presented together with the CO conversion, which in both cases was monitored by mass spectrometry. A red-shift of the vibrational frequency of linearly bonded CO which correlates with a blue-shift of the Pt L-III binding energy indicates that the Pt catalyst initially is partially oxidised and gradually reduced when the O-2 supply is switched off. Control experiments with a NO2 oxidised Pt/Al2O3 catalyst support these findings. A hysteresis in the catalytic activity due to the different rates whereby Pt is oxidised and reduced as a function of gas-phase composition is observed. The activation energy for the Pt oxide reduction (decomposition) process is estimated to be about 50 kJ/mol. The results further emphasise that the conventional three-step Langmuir-Hinshelwood (LH) scheme used to interpret CO oxidation on Pt surfaces must be complemented by a Pt oxidation and reduction mechanism during transient conditions. Moreover, FTIR data suggest that during the extinction, the partially oxidised platinum surface is reduced by chemisorbed CO which should be explicitly accounted for in the modeling of the reaction mechanism. (C) 2004 Elsevier Inc. All rights reserved.

  • 6.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lågdimensionella material för generering av solbränsle2017Conference paper (Other academic)
  • 7.
    Ghaly, Montaser
    et al.
    National Research Centre (NRC), Chemical Engineering and Pilot Plant Department, Cairo, Egypt.
    Ali, Mohamed Eid
    National Research Centre (NRC), Water Pollution Research Department, P.O. 11312, Cairo, Egypt.
    Österlund, Lars
    FOI CBRN Defence and Security, Umeå.
    Khattab, Ibrahim
    National Research Centre (NRC), Chemical Engineering and Pilot Plant Department, Cairo, Egypt.
    Badawy, Mohamed
    National Research Centre (NRC), Water Pollution Research Department, P.O. 11312, Cairo, Egypt.
    Farah, Joseph
    National Research Centre (NRC), Chemical Engineering and Pilot Plant Department, Cairo, Egypt.
    Zaher, Fatama
    National Research Centre (NRC), Chemical Engineering and Pilot Plant Department, Cairo, Egypt.
    Al-Maghrabi, Mohammednoor
    Faculty of Engineering, King Abdul-Aziz University, Jedddah, Saudi Arabia.
    ZnO/spiral-shaped glass for solar photocatalytic oxidation of Reactive Red 1202014In: Arabian Journal of Chemistry, ISSN 1878-5352Article in journal (Refereed)
    Abstract [en]

    ZnO/glass spiral (GS) was prepared by immobilization of ZnO on GS with facilemethod, and was characterized by X-ray diffraction analysis (XRD), scanning electron microscope(SEM) and the crystallite size of ZnO on GS surface was calculated. SEM showed rod-like shape ofZnO particles on GS surface. Photocatalytic activity of prepared immobilized photocatalyst wasinvestigated for decolourization and degradation of C.I. Reactive Red 120 (RR-120) dye under sunlight.The kinetics of decolourization and degradation removal has been investigated. The effect ofpH on decolourization and degradation of dye was studied. The decolourization and degradation ofdye were followed by pseudo-first order reaction. The decolourization and degradation of RR-120dye were enhanced by H2O2 addition to definite dosage beyond that the effect is diminished. Also,the reusability of immobilized ZnO on GS was tested for photocatalytic degradation of dye and itwas worth noting that it has high efficiency with slight decrease (5%) after five successive runs.

  • 8. Khattab, Ibrahim A.
    et al.
    Ghaly, Montaser Y.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ali, Mohamed E. M.
    Farah, Joseph Y.
    Zaher, Fatama M.
    Badawy, Mohamed I.
    Photocatalytic degradation of azo dye Reactive Red 15 over synthesized titanium and zinc oxides photocatalysts: a comparative study2012In: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986, Vol. 48, no 1-3, p. 120-129Article in journal (Refereed)
    Abstract [en]

    Nanoparticle TiO2 and ZnO were prepared by facile method. The XRD pattern study shows that there is no obvious difference in crystal composition of various shapes of TiO2 and ZnO. The photocatalytic degradation of Reactive Red 15, commonly used as a textile dye, using synthesized titanium and zinc oxides was investigated. The effects of influential parameters such as initial pH, catalyst loading, initial dye concentration and addition of hydrogen peroxide were studied. The degradation efficiency was expressed by the removal of color and chemical oxygen demand (COD). The study reveals that: (1) Both catalysts, under corresponding optimal conditions, can be employed as an effective photocatalyst for the elimination of color and COD from dye wastewater. Also, ZnO is more efficient catalyst than TiO2; (2) Addition of proper amount of hydrogen peroxide improves both the decolorization and the degradation of the dye; (3) The photocatalytic degradation of Reactive Red 15, in the presence of both photocatalysts, obeyed pseudo-first order kinetics. The biodegradability ratio BOD5/COD increases from original zero up to 0.52 and 0.6 within 90 minutes irradiation time using 1 and 0.75 g/L TiO2 and ZnO, respectively.

  • 9.
    Ma, Yue
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Asfaw, Habtom Desta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    A General Method to Fabricate Free-Standing Electrodes: Sulfonate Directed Synthesis and their Li+ Storage Properties2015In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 11, p. 3957-3965Article in journal (Refereed)
    Abstract [en]

    For materials based on a spatially varied conversion reaction, Li+ storage properties largely hinge on the rational design of the concurrent electronic and ionic pathways in the electrode. We herein present a scalable approach for integrating size-tunable Fe3O4 nanocrystals with hierarchical porous carbon foam by employing sulfonated high internal phase emulsion polymers (polyHIPE) as the carbon source and substrate. To verify the feasibility of our configuration design, the electrodes of such a type were directly evaluated in pouch cells without using an auxiliary binder or a metallic current collector: The best performing composite electrode, with optimized oxide size range, exhibits a good capacity retention of 89.7% of the first charge capacity after 100 cycles and high rate durability up to 4 A g–1. Furthermore, this synthetic approach was also applied to develop carbon/FeS free-standing anodes using the sulfonate groups as the sulfur source, demonstrating its generic applicability to the fabrication of other free-standing electrodes with enhanced Li+ storage properties.

  • 10.
    Proper, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Development of localized electrochemical deposition2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the manufacturing industry, parts are created with high demands on their mechanical properties. To avoid surface defects, components are over-dimensioned and then machined to the desired size. This will give rise to material waste and extra processing steps. Therefore, it is of interest to investigate methods to repair these surface defects without the need of over-dimensioning.

    In this thesis work, different strategies for localized electrochemical deposition have been investigated with respect to their ability to perform local repair of surface defects. The concepts that have been studied include the application of a microanode, a confined bath, and of liquid marbles.

    The different methods were tested and the process parameters were optimized to achieve good quality deposits at sufficient growth rates. The best deposits were then further characterized with respect to grain size distribution, crystal orientation and surface quality. The ability to repair a surface defect was also studied along with the possibility of producing thicker deposits. The confined bath method was the most promising concept. At a current density of 3.5 A/dm2, a good quality deposit was achieved. The crystal orientations proved to be random and the average grain size was 115 ± 61 nm. A surface defect with a depth of 33.0 µm and a width of 19.8 µm was successfully repaired using this local deposition method. However, the technique needs further development for the desired application in manufacturing industry.

  • 11.
    Rajagopalan, Kishore
    University of Illinois at Urbana Champaign.
    31. Minimising Industrial Wastes from the Fabricated Metal Products Industries2012In: Ecology and Animal Health / [ed] Leif Norrgren and Jeffrey Levengood, Uppsala: Baltic University Press , 2012, 1, p. 249-256Chapter in book (Other (popular science, discussion, etc.))
  • 12.
    Sekretaryova, Alina N.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Linkoping Univ, Dept Phys Chem & Biol, S-58183 Linkoping, Sweden.
    Vagin, Mikhail Yu
    Linkoping Univ, Dept Phys Chem & Biol, S-58183 Linkoping, Sweden;Linkoping Univ, Dept Sci & Technol, Lab Organ Elect, S-60174 Norrkoping, Sweden.
    Volkov, Anton V.
    Linkoping Univ, Dept Sci & Technol, Lab Organ Elect, S-60174 Norrkoping, Sweden.
    Zozoulenko, Igor, V
    Linkoping Univ, Dept Sci & Technol, Lab Organ Elect, S-60174 Norrkoping, Sweden.
    Eriksson, Mats
    Linkoping Univ, Dept Phys Chem & Biol, S-58183 Linkoping, Sweden.
    Evaluation of the Electrochemically Active Surface Area of Microelectrodes by Capacitive and Faradaic Currents2019In: CHEMELECTROCHEM, ISSN 2196-0216, Vol. 6, no 17, p. 4411-4417Article in journal (Refereed)
    Abstract [en]

    Two experimental methods to estimate the electrochemically active surface area (EASA) of microelectrodes are investigated. One method is based on electrocapacitive measurements and depends significantly on the surface roughness as well as on other parameters. The other method is based on faradaic current measurements and depends on the geometric surface area. The experimental results are supplemented with numerical modeling of electrodes with different surface roughness. A systematic study reveals a strong influence of the scale and arrangement of the surface roughness, the measurement potential and the electrolyte concentration on the EASA of microelectrodes estimated from the electrocapacitive measurements. The results show that electrocapacitive measurements should not be used to estimate the faradaic EASA of microelectrodes with a non-negligible surface roughness.

  • 13.
    Stefanov, Bozhidar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Photocatalysis for Indoor Air Cleaning: In situ FTIR and DFT Study of Acetaldehyde Photo-Oxidation on TiO2 and Sulfate-Modified TiO22013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Acetaldehyde is among the group of VOC’s causing the so-called "sick building" syndrome. WHO has estimated that this problem, related to the indoor air-quality, affects one third of all buildings worldwide. TiO2 is an attractive material for the photocatalytic removal of VOC’s in the indoor environment. Deactivation of the photocatalyst is, however, commonly deteriorating its performance over usage time, and ways to mitigate this problem must be invented. Thus modification of TiO2 surface properties is an area of considerable interest. It is possible to enhance the surface acidity of TiO2 through sulfation which effectively lowers the affinity of acidic intermediates. In addition, surface modification of photocatalysts may be used to control adsorption and wetting properties, as well as providing scavengers for photo-excited electrons and holes to suppress unwanted recombination and increase the quantum yield.

    In this work the interaction of gaseous acetaldehyde with TiO2 and SO4-modified anatase TiO2 is investigated. Films were prepared by doctor-blading of commercial TiO2 nanoparticle suspensions and characterized by means of XRD and TEM. The adsorption and photo-oxidation of acetaldehyde were studied with in situ FTIR spectroscopy and DFT calculations.

    On TiO2 nanoparticles, which exhibit predominantly (101) facets, in situ FTIR shows that acetaldehyde adsorption is accompanied by the appearance of a hitherto non-assigned absorption band at 1643 cm−1, shown to be due to acetaldehyde dimers. The results are supported by DFT calculations performed at the M06/6-31++G** level. Vibrational frequencies calculated within a partially relaxed cluster model for molecular acetaldehyde and its dimer, and for the corresponding adsorbed species on the anatase (101) surface, were in good agreement with the experimental results. Inclusion of dimer formation is shown to give an improved description of the reaction kinetics on TiO2.

    Based on mode-resolved in situ FTIR, kinetic models were constructed, which describe the observed photo-oxidation surface products on both TiO2 and SO4-modified TiO2. The surface concentration of main surface products and corresponding reaction rates were determined. It was observed that formate is the major reaction product, whose further oxidation limits the complete oxidation to gaseous species. Formate thus acts as an inhibitor, blocking adsorption sites, and is responsible for photocatalyst deactivation. The oxidation reaction is characterized by two reaction pathways, one fast and one slow, associated with two types of surface reaction sites. On the SO4-modified TiO2 fewer intermediates are accumulated, and it resists deactivation much better compared with the pure TiO2 photocatalyst, which is attributed to the acidic character of the modified surface. The results presented here are of interest for applications to photocatalytic air purification, and surfaces with controlled wettability.

    List of papers
    1. Acetaldehyde adsorption and condensation on anatase TiO2: Influence of acetaldehyde dimerization
    Open this publication in new window or tab >>Acetaldehyde adsorption and condensation on anatase TiO2: Influence of acetaldehyde dimerization
    2014 (English)In: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 381, p. 77-88Article in journal (Refereed) Published
    Abstract [en]

    Conversion of acetaldehyde to crotonaldehyde on anatase TiO2 films was studied by in situ Fourier transform infrared spectroscopy (FTIR) and by density functional theory (DFT) calculations. In situ FTIR showed that acetaldehyde adsorption is accompanied by the appearance of a hitherto non-assigned absorption band at 1643 cm−1, which is shown to be due to acetaldehyde dimers. The results were supported by DFT calculations. Vibrational frequencies calculated within a partially relaxed cluster model for molecular acetaldehyde and its dimer, and for the corresponding adsorbed species on the anatase (101) surface, were in good agreement with experimental results. A kinetic model was constructed based on the combined FTIR and DFT results, and was shown to explain the essential features of the acetaldehyde condensation reaction.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    TiO2, acetaldehyde, Crotonaldehyde, Dimer, Adsorption, DFT, FTIR
    National Category
    Chemical Process Engineering Nano Technology Inorganic Chemistry Theoretical Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry; Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-209695 (URN)10.1016/j.molcata.2013.10.005 (DOI)000329384300011 ()
    Projects
    EU GRINDOOR
    Funder
    EU, FP7, Seventh Framework Programme, 267234Swedish Research Council, VR 2010-3514
    Available from: 2013-10-26 Created: 2013-10-24 Last updated: 2017-12-06Bibliographically approved
    2. Adsorption and photo-oxidation of acetaldehyde on TiO2 and sulfate-modified TiO2: Studies by in situ FTIR spectroscopy and micro-kinetic modeling
    Open this publication in new window or tab >>Adsorption and photo-oxidation of acetaldehyde on TiO2 and sulfate-modified TiO2: Studies by in situ FTIR spectroscopy and micro-kinetic modeling
    2013 (English)In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 307, p. 265-274Article in journal (Refereed) Published
    Abstract [en]

    Adsorption and photocatalytic oxidation of acetaldehyde have been investigated on TiO2 and sulfate-modified TiO2 films (denoted SO4TiO2). In situ Fourier transform infrared spectroscopy was used to study surface reactions as a function of time and number of experimental cycles. Spectral analysis and micro-kinetic modeling show that crotonaldehyde formation occurs spontaneously on TiO2 but is impeded on SO4TiO2, where instead acetaldehyde desorption is significant. Photo-oxidation yields significant amounts of formate on TiO2 and was identified as the rate-determining step and associated with site blocking. Significantly smaller amounts of formate were observed on SO4TiO2, which is due to the acidity of this surface resulting in weaker bonding of aldehyde and carboxylate intermediate species. Our results are of considerable interest for applications to photocatalytic air purification and to surfaces with controlled wettability.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    Acetaldehyde, TiO2, Photocatalysis, In situ Fourier transform infrared spectroscopy, Micro-kinetic modeling, Acid–base properties, Surface functionalization
    National Category
    Inorganic Chemistry Chemical Process Engineering Nano Technology
    Research subject
    Engineering Science with specialization in Nanotechnology and Functional Materials; Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-209690 (URN)10.1016/j.jcat.2013.08.004 (DOI)000327903900029 ()
    Funder
    EU, European Research Council, ERC Advanced Grant 267234Swedish Research Council, VR 2010-3514
    Available from: 2013-10-26 Created: 2013-10-24 Last updated: 2017-12-06Bibliographically approved
  • 14.
    Stefanov, Bozhidar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Fine control of the amount of preferential <001> orientation in DC magnetron sputtered nanocrystalline TiO2 film2014In: 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, p. UNSP 012011-Conference 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.

  • 15.
    Stefanov, Bozhidar I
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Topalian, Zareh
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Acetaldehyde adsorption and condensation on anatase TiO2: Influence of acetaldehyde dimerization2014In: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 381, p. 77-88Article in journal (Refereed)
    Abstract [en]

    Conversion of acetaldehyde to crotonaldehyde on anatase TiO2 films was studied by in situ Fourier transform infrared spectroscopy (FTIR) and by density functional theory (DFT) calculations. In situ FTIR showed that acetaldehyde adsorption is accompanied by the appearance of a hitherto non-assigned absorption band at 1643 cm−1, which is shown to be due to acetaldehyde dimers. The results were supported by DFT calculations. Vibrational frequencies calculated within a partially relaxed cluster model for molecular acetaldehyde and its dimer, and for the corresponding adsorbed species on the anatase (101) surface, were in good agreement with experimental results. A kinetic model was constructed based on the combined FTIR and DFT results, and was shown to explain the essential features of the acetaldehyde condensation reaction.

  • 16.
    Topalian, Zareh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Stefanov, Bozhidar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Adsorption and photo-oxidation of acetaldehyde on TiO2 and sulfate-modified TiO2: Studies by in situ FTIR spectroscopy and micro-kinetic modeling2013In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 307, p. 265-274Article in journal (Refereed)
    Abstract [en]

    Adsorption and photocatalytic oxidation of acetaldehyde have been investigated on TiO2 and sulfate-modified TiO2 films (denoted SO4TiO2). In situ Fourier transform infrared spectroscopy was used to study surface reactions as a function of time and number of experimental cycles. Spectral analysis and micro-kinetic modeling show that crotonaldehyde formation occurs spontaneously on TiO2 but is impeded on SO4TiO2, where instead acetaldehyde desorption is significant. Photo-oxidation yields significant amounts of formate on TiO2 and was identified as the rate-determining step and associated with site blocking. Significantly smaller amounts of formate were observed on SO4TiO2, which is due to the acidity of this surface resulting in weaker bonding of aldehyde and carboxylate intermediate species. Our results are of considerable interest for applications to photocatalytic air purification and to surfaces with controlled wettability.

  • 17.
    Vargas Catalan, Ernesto
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Design and Manufacturing of a Rotationally Symmetric Cold Gas Nozzle in Silicon2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis, the goal was to devise design patterns and a fabrication processfor manufacturing a 3-D rotationally symmetric converging-diverging cold gasmicronozzle in silicon.The report explains the theory of etching and the methods involved. The work beginswith calculations and simulations of the etching processes. The chosen etch techniqueutilizes so called microloading and reactive ion etching lag effects, which essentially arephenomena where the etch rate can be adjusted by breaking up mask features intosubpatterns, and the etch depth for a given recipe and time can be made to differlocally. The subpatterns consisted of very small rectangles and triangles withalternating concentration. Five different recipes for the reactive ion etching weretried, where the coil power, platen power, pressure, temperature and time wasvaried.Etch rates could be made to differ locally depending on the concentration ofsubpatterns within the mask feature. The etch rates were also affected by the recipeparameters such as coil power, platen power, and pressure. High coil and platenpower increased the etch rate, while high pressure reduced the etch rate. The platenpower also affected the surface roughness.A solution for reducing misalignment problems in the future for the fusion bondingprocess resulted in the proposed moiré patterns that were made to showmisalignments down to 0.2 μm.Through scanning electron microscopy, the Nozzle 5_4_2 was concluded to have themost rotationally symmetric cross section at both the throat and the outlet. It hasthroat diameter of 31.1 μm with a depth of 34.2 μm and an outlet diameter of146.4 μm with a depth of 113.2 μm

  • 18.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Passive and Active Micromixers2009In: Handbook of Micro Reactors: Vol.1: Fundamentals, Operations and Catalysts / [ed] V. Hessel, J.C. Schouten, A. Renken, and J.-I. Yoshida,, Weinheim: Wiley-VCH Verlagsgesellschaft, 2009, 1Chapter in book (Refereed)
  • 19.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Operando studies of surface reactions in photocatalysis: Photocatalytic oxidation of propane in dry and humid ar on anatase and rutile TiO2 nanoparticles2010In: Trends in photochemistry and photobiology, ISSN 0972-4532, Vol. 12, p. 53-64Article in journal (Refereed)
    Abstract [en]

    The photo-oxidation of propane in dry and humid synthetic air was studied on anatase and rutile nanoparticles by operando diffuse reflectance Fourier-transform infrared (DRIFT) spectroscopy and mass spectrometry (MS). Analysis of the propane removal and CO2 production rate shows that the carbon mass balance (CMB) is CMB < 1 under all reaction conditions up to 1 h operation, and that it is significantly higher on rutile than anatase in humid reaction gas. Corresponding analysis of DRIFT spectra acquired simultaneously as the MS measurements shows that the CMB data scales with the concentration of surface species, i.e. the deviations from unity in the reactant-product mass balance (1-CMB) is quantitatively accounted for by a corresponding increase of surface species measured by DRIFT. The identity of surface species and rate determining reactions steps is deduced by fitting the mode-resolved vibrational IR bands to a kinetic model that accounts for observed temporal evolution of absorption bands. Photo-oxidation of acetone and formate is found to be rate determining on anatase and rutile, respectively. The importance of water is to hinder these surface species to bind to Ti cation surface sites; in particular the concentration of bridging-bidentate formate is reduced on rutile, which under dry conditions exhibits the lowest photo-degradation rate.

  • 20.
    Österlund, Lars
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mattsson, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lejon, Christian
    FOI.
    Mäkie, Peter
    Umeå Universitet.
    Deactivation mechanisms of transition metal oxide photocatalysts studied by operando surface infrared spectroscopy2011In: Deactivation mechanisms of transition metal oxide photocatalysts studied by operando surface infrared spectroscopy, American Chemical Society (ACS), 2011, p. 324-Conference paper (Refereed)
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