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  • 1.
    Arvizu, Miguel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wen, Rui-Tao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Klemberg-Sapieha, Jolanta Ewa
    Martinu, Ludvik
    Niklasson, Gunnar A.
    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.
    Galvanostatic ion de-trapping rejuvenates oxide thin films2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 48, p. 26387-26390Article in journal (Refereed)
    Abstract [en]

    Ion trapping under charge insertion-extraction is well-known to degrade the electrochemical performance of oxides. Galvano-static treatment was recently shown capable to rejuvenate the oxide, but the detailed mechanism remained uncertain. Here we report on amorphous electrochromic (EC) WO3 thin films prepared by sputtering and electrochemically cycled in a lithium-containing electrolyte under conditions leading to severe loss of charge exchange capacity and optical modulation span. Time-of-flight elastic recoil detection analysis (ToF-ERDA) documented pronounced Li+ trapping associated with the degradation of the EC properties and, importantly, that Li+ detrapping, caused by a weak constant current drawn through the film for some time, could recover the original EC performance. Thus, ToF-ERDA provided direct and unambiguous evidence for Li+ detrapping.

  • 2.
    Azuma, Tomoyuki
    et al.
    Univ Tokyo, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Teramura, Yuji
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology. Univ Tokyo, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Takai, Madoka
    Univ Tokyo, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Cellular Response to Non-contacting Nanoscale Sublayer: Cells Sense Several Nanometer Mechanical Property2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 17, p. 10710-10716Article in journal (Refereed)
    Abstract [en]

    Cell adhesion is influenced not only from the surface property of materials but also from the mechanical properties of the nanometer sublayer just below the surface. In this study, we fabricated a well-defined diblock polymer brush composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) and 2-aminoethyl methacrylate (AEMA). The underlying layer of poly(MPC) is a highly viscous polymer, and the surface layer of poly(AEMA) is a cell-adhesive cationic polymer. The adhesion of L929 mouse fibroblasts was examined on the diblock polymer brush to see the effect of a non contacting underlying polymer layer on the cell-adhesion behavior. Cells could sense the viscoelasticity of the underlying layers at the nanometer level, although the various fabricated diblock polymer brushes had the same surface property and the functional group. Thus, we found a new factor which could control cell spread at the nanometer level, and this insight would be important to design nanoscale biomaterials and interfaces.

  • 3. Balitskii, Olexiy A.
    et al.
    Sytnyk, Mykhailo
    Stangl, Julian
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Groiss, Heiko
    Heiss, Wolfgang
    Tuning the Localized Surface Plasmon Resonance in Cu2-xSe Nanocrystals by Postsynthetic Ligand Exchange2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 20, p. 17770-17775Article in journal (Refereed)
    Abstract [en]

    Nanoparticles exhibiting localized surface plasmon resonances (LSPR) are valuable tools traditionally used in a wide field of applications including sensing, imaging, biodiagnostics and medical therapy. Plasmonics in semiconductor nanocrystals is of special interest because of the tunability of the carrier densities in semiconductors, and the possibility to couple the plasmonic resonances to quantum confined excitonic transitions. Here, colloidal Cu2-xSe nanocrystals were synthesized, whose composition was shown by Rutherford backscattering analysis and electron dispersive X-ray spectroscopy, to exhibit Cu deficiency. The latter results in p-type doping causing LSPRs, in the present case around a wavelength of 1100 nm, closely matching the indirect band gap of Cu2-xSe. By partial exchange of the organic ligands to specific electron trapping or donating species the LSPR is fine-tuned to exhibit blue or red shifts, in total up to 200 nm. This tuning not only provides a convenient tool for post synthetic adjustments of LSPRs to specific target wavelength but the sensitive dependence of the resonance wavelength on surface charges makes these nanocrystals also interesting for sensing applications, to detect analytes dressed by functional groups.

  • 4.
    Baloukas, Bill
    et al.
    Polytech Montreal, Dept Engn Phys, Montreal.
    Arvizu, Miguel A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wen, Rui-Tao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    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.
    Vernhes, Richard
    Polytech Montreal, Dept Engn Phys, Montreal.
    Klemberg-Sapieha, Jolanta E.
    Polytech Montreal, Dept Engn Phys, Montreal.
    Martinu, Ludvik
    Polytech Montreal, Dept Engn Phys, Montreal.
    Galvanostatic Rejuvenation of Electrochromic WO3 Thin Films: Ion Trapping and Detrapping Observed by Optical Measurements and by Time-of-Flight Secondary Ion Mass Spectrometry2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 20, p. 16996-17002Article in journal (Refereed)
    Abstract [en]

    Electrochromic (EC) smart windows are able to decrease our energy footprint while enhancing indoor comfort and convenience. However, the limited durability of these windows, as well as their cost, result in hampered market introduction. Here, we investigate thin films of the most widely studied EC material, WO3. Specifically, we combine optical measurements (using spectrophotometry in conjunction with variable-angle spectroscopic ellipsometry) with time-of-flight secondary ion mass spectrometry and atomic force microscopy. Data were taken on films in their as-deposited state, after immersion in a Li-ion-conducting electrolyte, after severe degradation by harsh voltammetric cycling and after galvanostatic rejuvenation to regain the original EC performance. Unambiguous evidence was found for the trapping and detrapping of Li ions in the films, along with a thickness increase or decrease during degradation and rejuvenation, respectively. It was discovered that (i) the trapped ions exhibited a depth gradient; (ii) following the rejuvenation procedure, a small fraction of the Li ions remained trapped in the film and gave rise to a weak short-wavelength residual absorption; and (iii) the surface roughness of the film was larger in the degraded state than in its virgin and rejuvenated states. These data provide important insights into the degradation mechanisms of EC devices and into means of achieving improved durability.

  • 5.
    Barba, Albert
    et al.
    Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Universitat Politecnica de Catalunya.
    Diez-Escudero, Anna
    Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Universitat Politecnica de Catalunya.
    Maazouz, Yassine
    Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Universitat Politecnica de Catalunya.
    Rappe, Katrin
    Bone Healing Group, Small Animal Surgery Department, Veterinary School, Universitat Autonoma de Barcelona.
    Espanol, Montserrat
    Barcelona Research Center in Multiscale Science and Engineering, Universitat Politecnica de Catalunya.
    Montufar, Edgar B
    Barcelona Research Center in Multiscale Science and Engineering, Universitat Politecnica de Catalunya.
    Bonany, Mar
    Barcelona Research Center in Multiscale Science and Engineering, Universitat Politecnica de Catalunya.
    Sadowska, Joanna M
    Barcelona Research Center in Multiscale Science and Engineering, Universitat Politecnica de Catalunya.
    Guillem-Marti, Jordi
    Barcelona Research Center in Multiscale Science and Engineering, Universitat Politecnica de Catalunya.
    Öhman, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Manzanares, Maria-Cristina
    Human Anatomy and Embryology Unit, Department of Pathology and Experimental Therapeutics, Universitat de Barcelona.
    Franch, Jordi
    Bone Healing Group, Small Animal Surgery Department, Veterinary School, Universitat Autonoma de Barcelona.
    Ginebra, Maria-Pau
    Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Universitat Politecnica de Catalunya.
    Osteoinduction by Foamed and 3D-Printed Calcium Phosphate Scaffolds: Effect of Nanostructure and Pore Architecture2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 48, p. 41722-41736Article in journal (Refereed)
    Abstract [en]

    Some biomaterials are osteoinductive, that is, they are able to trigger the osteogenic process by inducing the differentiation of mesenchymal stem cells to the osteogenic lineage. Although the underlying mechanism is still unclear, microporosity and specific surface area (SSA) have been identified as critical factors in material-associated osteoinduction. However, only sintered ceramics, which have a limited range of porosities and SSA, have been analyzed so far. In this work, we were able to extend these ranges to the nanoscale, through the foaming and 3D-printing of biomimetic calcium phosphates, thereby obtaining scaffolds with controlled micro- and nanoporosity and with tailored macropore architectures. Calcium-deficient hydroxyapatite (CDHA) scaffolds were evaluated after 6 and 12 weeks in an ectopic-implantation canine model and compared with two sintered ceramics, biphasic calcium phosphate and β-tricalcium phosphate. Only foams with spherical, concave macropores and not 3Dprinted scaffolds with convex, prismatic macropores induced significant ectopic bone formation. Among them, biomimetic nanostructured CDHA produced the highest incidence of ectopic bone and accelerated bone formation when compared with conventional microstructured sintered calcium phosphates with the same macropore architecture. Moreover, they exhibited different bone formation patterns; in CDHA foams, the new ectopic bone progressively replaced the scaffold, whereas in sintered biphasic calcium phosphate scaffolds, bone was deposited on the surface of the material, progressively filling the pore space. In conclusion, this study demonstrates that the high reactivity of nanostructured biomimetic CDHA combined with a spherical, concave macroporosity allows the pushing of the osteoinduction potential beyond the limits of microstructured calcium phosphate ceramics.

  • 6.
    Bi, Dongqin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    El-Zohry, Ahmed M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Improved Morphology Control Using a Modified Two-Step Method for Efficient Perovskite Solar Cells2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 21, p. 18751-18757Article in journal (Refereed)
    Abstract [en]

    A two-step wet chemical synthesis method for methylammonium lead(II) triiodide (CH3NH3PbI3) perovskite is further developed for the preparation of highly reproducible solar cells, with the following structure: fluorine-doped tin oxide (FTO)/TiO2 (compact)/TiO2 (mesoporous)/CH3NH3PbI3/spiro-OMeTAD/Ag. The morphology of the perovskite layer could be controlled by careful variation of the processing conditions. Specifically, by modifying the drying process and inclusion of a dichloromethane treatment, more uniform films could be prepared, with longer emission lifetime in the perovskite material and longer electron lifetime in solar cell devices, as well as faster electron transport and enhanced charge collection at the selective contacts. Solar cell efficiencies up to 13.5% were obtained.

  • 7.
    Cappel, Ute B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Lanzilotto, Valeria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Johansson, Fredrik O. L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Aitola, Kerttu
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Giangrisostomi, Erika
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Ovsyannikov, Ruslan
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Leitner, Torsten
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Foehlisch, Alexander
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.;Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Uppsala Berlin Joint Lab Next Generat Photoelectr, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Rensmo, Håkan
    Partially Reversible Photoinduced Chemical Changes in a Mixed-Ion Perovskite Material for Solar Cells2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 40, p. 34970-34978Article in journal (Refereed)
    Abstract [en]

    Metal halide perovskites have emerged as materials of high interest for solar energy-to-electricity conversion, and in particular, the use of mixed-ion structures has led to high power conversion efficiencies and improved stability. For this reason, it is important to develop means to obtain atomic level understanding of the photoinduced behavior of these materials including processes such as photoinduced phase separation and ion migration. In this paper, we implement a new methodology combining visible laser illumination of a mixed-ion perovskite ((FAP-bI(3))(0.85)(MAPbBr(3))(0.15)) with the element specificity and chemical sensitivity of core-level photoelectron spectroscopy. By carrying out measurements at a synchrotron beamline optimized for low X-ray fluxes, we are able to avoid sample changes due to X-ray illumination and are therefore able to monitor what sample changes are induced by visible illumination only. We find that laser illumination causes partially reversible chemistry in the surface region, including enrichment of bromide at the surface, which could be related to a phase separation into bromide- and iodide-rich phases. We also observe a partially reversible formation of metallic lead in the perovskite structure. These processes occur on the time scale of minutes during illumination. The presented methodology has a large potential for understanding light-induced chemistry in photoactive materials and could specifically be extended to systematically study the impact of morphology and composition on the photostability of metal halide perovskites.

  • 8.
    Chen, Song
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Shi, Liyang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Hunan Univ, Coll Biol, Changsha 410082, Hunan, Peoples R China.
    Luo, Jun
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Novel Fast-Setting Mineral Trioxide Aggregate: Its Formulation, Chemical-Physical Properties, and Cytocompatibility2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 24, p. 20334-20341Article in journal (Refereed)
    Abstract [en]

    One of the main drawbacks that limits the application of mineral trioxide aggregate (MTA) in dental field is its long setting time. Mineral trioxide aggregate with accelerated setting properties and excellent chemical-physical and biological properties is still required. In this study, an innovative mineral trioxide aggregate, which consists of calcium silicates, calcium aluminates, and zirconium oxide, was designed to obtain fast-setting property. The optimized formulation can achieve initial setting in 10 min and final setting in 15 min, which are much faster than commercial mineral trioxide aggregate. In addition, the optimized fast-setting MTA showed adequate radiopacity and good biocompatibility. The ion concentrations after storage in water for 1 day were 52.3 mg/L Ca, 67.7 mg/L Al, 48.8 mg/L Si, and 11.7 mg/L Mg. The hydration products of hardened cements were investigated by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared, showing the accelerated setting time was due to the formation of honeycomb-like calcium silicate hydrate gel. The novel MTA could be a promising material for dental applications.

  • 9. Corkhill, Claire L.
    et al.
    Myllykyla, Emmi
    Bailey, Daniel J.
    Thornber, Stephanie M.
    Qi, Jiahui
    Maldonado, Pablo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Stennett, Martin C.
    Hamilton, Andrea
    Hyatt, Neil C.
    Contribution of Energetically Reactive Surface Features to the Dissolution of CeO2 and ThO2 Analogues for Spent Nuclear Fuel Microstructures2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 15, p. 12279-12289Article in journal (Refereed)
    Abstract [en]

    In the safety case for the geological disposal of nuclear waste, the release of radioactivity from the repository is controlled by the dissolution of the spent fuel in groundwater. There remain several uncertainties associated with understanding spent fuel dissolution, including the contribution of energetically reactive surface sites to the dissolution rate. In this study, we investigate how surface features influence the dissolution rate of synthetic CeO2 and ThO2, spent nuclear fuel analogues that approximate as closely as possible the microstructure characteristics of fuel-grade UO2 but are not sensitive to changes in oxidation state of the cation. The morphology of grain boundaries (natural features) and surface facets (specimen preparation-induced features) was investigated during dissolution. The effects of surface polishing on dissolution rate were also investigated. We show that preferential dissolution occurs at grain boundaries, resulting in grain boundary decohesion and enhanced dissolution rates. A strong crystallographic control was exerted, with high misorientation angle grain boundaries retreating more rapidly than those with low misorientation angles, which may be due to the accommodation of defects in the grain boundary structure. The data from these simplified analogue systems support the hypothesis that grain boundaries play a role in the so-called "instant release fraction" of spent fuel, and should be carefully considered, in conjunction with other chemical effects, in safety performance assessements for the geological disposal of spent fuel. Surface facets formed during the sample annealing process also exhibited a strong crystallographic control and were found to dissolve rapidly on initial contact with dissolution medium. Defects and strain induced during sample polishing caused an overestimation of the dissolution rate, by up to 3 orders of magnitude.

  • 10.
    D'Amario, Luca
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Jiang, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Cappel, Ute B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Gibson, Elizabeth A.
    Newcastle Univ, Sch Chem, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Royal Inst Technol KTH, Ctr Mol Devices, Dept Chem, S-10044 Stockholm, Sweden.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Sun, Licheng
    Royal Inst Technol KTH, Ctr Mol Devices, Dept Chem, S-10044 Stockholm, Sweden.; Organ Chem Royal Inst Technol KTH, Dept Chem, S-10044 Stockholm, Sweden..
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Tian, Haining
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Royal Inst Technol KTH, Ctr Mol Devices, Dept Chem, S-10044 Stockholm, Sweden.
    Chemical and Physical Reduction of High Valence Ni States in Mesoporous NiO Film for Solar Cell Application.2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 39, p. 33470-33477Article in journal (Refereed)
    Abstract [en]

    The most common material for dye-sensitized photocathodes is mesoporous NiO. We transformed the usual brownish NiO to be more transparent by reducing high valence Ni impurities. Two pretreatment methods have been used: chemical reduction by NaBH4 and thermal reduction by heating. The power conversion efficiency of the cell was increased by 33% through chemical treatment, and an increase in open-circuit voltage from 105 to 225 mV was obtained upon heat treatment. By optical spectroelectrochemistry, we could identify two species with characteristically different spectra assigned to Ni3+ and Ni4+. We suggest that the reduction of surface Ni3+ and Ni4+ to Ni2+ decreases the recombination reaction between holes on the NiO surface with the electrolyte. It also keeps the dye firmly on the surface, building a barrier for electrolyte recombination. This causes an increase in open-circuit photovoltage for the treated film.

  • 11.
    Doubaji, Siham
    et al.
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Ma, Lu
    Argonne Naional Laboratory.
    Asfaw, Habtom Desta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Izanzar, Ilyasse
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Xu, Rui
    Argonne National Laboratory.
    Alami, Jones
    Mohammed VI Polytechnic University (UM6P), Ben Guerir, Morocco.
    Lu, Jun
    Argonne National Laboratory.
    Wu, Tianpin
    Argonne National Laboratory.
    Amine, Khalil
    Argonne National Laboratory.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Saadoune, Ismael
    LCME, University Cadi Ayyad, Marrakech, Morocco.; Mohammed VI Polytech Univ UM6P, Mat Sci & Nanoengn Dept, Lot 660 Hay My Rachid, Ben Guerir 43150, Morocco..
    On the P2-NaxCo1−y(Mn2/3Ni1/3)yO2 Cathode Materials for Sodium-Ion Batteries: Synthesis, Electrochemical Performance, and Redox Processes Occurring during the Electrochemical Cycling2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 1, p. 488-501Article in journal (Refereed)
    Abstract [en]

    P2-type NaMO2sodiated layered oxides withmixed transition metals are receiving considerable attention foruse as cathodes in sodium-ion batteries. A study on solidsolution (1−y)P2-NaxCoO2−(y)P2-NaxMn2/3Ni1/3O2(y=0,1/3, 1/2, 2/3, 1) reveals that changing the composition of thetransition metals affects the resulting structure and the stabilityof pure P2 phases at various temperatures of calcination. For 0≤y≤1.0, the P2-NaxCo(1−y)Mn2y/3Niy/3O2solid-solutioncompounds deliver good electrochemical performance whencycled between 2.0 and 4.2 V versus Na+/Na with improved capacity stability in long-term cycling, especially for electrodematerials with lower Co content (y= 1/2 and 2/3), despite lower discharge capacities being observed. The (1/2)P2-NaxCoO2−(1/2)P2-NaxMn2/3Ni1/3O2composition delivers a discharge capacity of 101.04 mAh g−1with a capacity loss of only 3% after 100cycles and a Coulombic efficiency exceeding 99.2%. Cycling this material to a higher cutoffvoltage of 4.5 V versus Na+/Naincreases the specific discharge capacity to≈140 mAh g−1due to the appearance of a well-defined high-voltage plateau, but afteronly 20 cycles, capacity retention declines to 88% and Coulombic efficiency drops to around 97%. In situ X-ray absorption near-edge structure measurements conducted on composition NaxCo1/2Mn1/3Ni1/6O2(y= 1/2) in the two potential windows studiedhelp elucidate the operating potential of each transition metal redox couple. It also reveals that at the high-voltage plateau, all ofthe transition metals are stable, raising the suspicion of possible contribution of oxygen ions in the high-voltage plateau.

  • 12.
    Dwibedi, Debasmita
    et al.
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ling, Chris D.
    Univ Sydney, Sch Chem, Bldg F11, Sydney, NSW 2006, Australia..
    Araujo, Rafael B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Duraisamy, Shanmughasundaram
    Indian Inst Sci, Inorgan & Phys Chem, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Munichandraiah, Nookala
    Indian Inst Sci, Inorgan & Phys Chem, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Barpanda, Prabeer
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ionothermal Synthesis of High-Voltage Alluaudite Na2+2xFe2-x(SO4)(3) Sodium Insertion Compound: Structural, Electronic, and Magnetic Insights2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 11, p. 6982-6991Article in journal (Refereed)
    Abstract [en]

    Exploring future cathode materials for sodium-ion batteries, alluaudite class of Na2Fe2II(SO4)(3) has been recently unveiled as a 3.8 V positive insertion candidate (Barpanda et al. Nat. Commun. 2014, 5, 4358). It forms an Fe-based polyanionic compound delivering the highest Fe-redox potential along with excellent rate kinetics and reversibility. However, like all known SO4-based insertion materials, its synthesis is cumbersome that warrants careful processing avoiding any aqueous exposure. Here, an alternate low temperature ionothermal synthesis has been described to produce the alluaudite Na2+2xFe2-xII(SO4)(3). It marks the first demonstration of solvothermal synthesis of alluaudite Na2+2xM2-xII(SO4)(3) (M = 3d metals) family of cathodes. Unlike classical solid-state route, this solvothermal route favors sustainable synthesis of homogeneous nanostructured alluaudite products at only 300 degrees C, the lowest temperature value until date. The current work reports the synthetic aspects of pristine and modified ionothermal synthesis of Na2+2xFe2-xII(SO4)(3) having tunable size (300 nm similar to 5 mu m) and morphology. It shows antiferromagnetic ordering below 12 K. A reversible capacity in excess of 80 mAh/g was obtained with good rate kinetics and cycling stability over 50 cycles. Using a synergistic approach combining experimental and ab initio DFT analysis, the structural, magnetic, electronic, and electrochemical properties and the structural limitation to extract full capacity have been described.

  • 13. Espanol, Montserrat
    et al.
    Mestres, Gemma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Luxbacher, Thomas
    Dory, Jean-Baptiste
    Ginebra, Maria-Pau
    Impact of Porosity and Electrolyte Composition on the Surface Charge of Hydroxyapatite Biomaterials2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 1, p. 908-917Article in journal (Refereed)
    Abstract [en]

    The success or failure of a material when implanted in the body is greatly determined by the surface properties of the material and the host tissue reactions. The very first event that takes place after implantation is the interaction of soluble ions, molecules and proteins from the biological environment with the material surface leading to the formation of an adsorbed protein layer that will later influence cell attachment. In this context, the particular topography and surface charge of a material become critical as they influence the nature of the proteins that will adsorb. However, very limited information is available on the surface charge of porous substrates. Only until very recently was the determination of the zeta potential on porous membranes accurately determined. The goal of this work was to implement the previous findings for the determination of the zeta potential of a series of porous hydroxyapatite (HA) substrates and to assess how porosity affects the measurements. In addition, studies using various electrolytes were also performed to prove how the specific affinity of certain ions for HA can further impact surface charge. The results showed that all materials exhibited very similar external surface charge (approximately −23 mV), consistent with their almost identical topographies. However, the presence of interconnected pores underneath the sample surface resulted in an additional internal zeta potential that varied with the porosity content. Measurements with different electrolytes confirmed the selectivity of divalent ions for HA underlying the importance of testing biomaterials using relevant electrolytes.

  • 14. Fan, Jiandong
    et al.
    Fabrega, Cristian
    Zamani, Reza R.
    Hao, Yan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Parra, Andres
    Andreu, Teresa
    Arbiol, Jordi
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ramon Morante, Joan
    Cabot, Andreu
    Enhanced Photovoltaic Performance of Nanowire Dye-Sensitized Solar Cells Based on Coaxial TiO2@TiO Heterostructures with a Cobalt(II/III) Redox Electrolyte2013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 20, p. 9872-9877Article in journal (Refereed)
    Abstract [en]

    The growth of a TiO shell at the surface of TiO2 nanowires (NWs) allowed us to improve the power conversion efficiency of NW-based dye-sensitized solar cells (DSCs) by a factor 2.5. TiO2@TiO core-shell NWs were obtained by a two-step process: First, rutile-phase TiO2 NWs were hydrothermally grown. Second, a hongquiite-phase TiO shell was electrochemically deposited at the surface of the TiO2 NWs. Bare TiO2 and heterojunction TiO2@TiO NW-based DSCs were obtained using a cobalt(II/III) redox electrolyte and LEG4 as the dye. With this electrolyte/dye combination, DSCs with outstanding V-oc values above 900 mV were systematically obtained. While TiO2@TiO NW-based DSCs had slightly lower V-oc values than bare TiO2 NW-based DSCs, they provided 3-fold higher photocurrents, overall reaching 2.5-fold higher power conversion efficiencies. The higher photocurrents were associated with the larger surface roughness and an enhanced charge-carrier separation/transfer at the NW/dye interface.

  • 15. Fan, Jiandong
    et al.
    Hao, Yan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Cabot, Andreu
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Cobalt(II/III) Redox Electrolyte in ZnO Nanowire-Based Dye-Sensitized Solar Cells2013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 6, p. 1902-1906Article in journal (Refereed)
    Abstract [en]

    In this work, we explore the use of cobalt complex redox shuttles in dye sensitized solar cells (DSCs) based on ZnO nanowires (NWs). Arrays of vertically aligned ZnO NWs produced by a low-cost hydrothermal method are used to fabricate DSCs with [Co(bpy)(3)](2+/3+) as electrolyte. A direct comparison of the performance of [Co(bpy)(3)](2+/3+)-based ZnO DSC with I-/I-3(-)-based ones demonstrates the higher suitability of the cobalt complex, both in terms of a larger open circuit voltage (V-OC) and a higher photocurrent. The [Co(bpy)(3)](2+/3+) electrolyte results in V-OC enhancements above 200 mV. This V-OC increase is associated to the better match between the cobalt complex redox potential and the oxidation potential of the dye. The incident photon-to-current efficiency (IPCE) enhancement is attributed to a less competitive visible light absorption of the cobalt redox couple. Thus the present study opens new opportunities to improve energy conversion efficiency in ZnO-based DSCs.

  • 16. Gavagnin, Marco
    et al.
    Wanzenboeck, Heinz D.
    Wachter, Stefan
    Shawrav, Mostafa M.
    Persson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gunnarsson, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Stoeger-Pollach, Michael
    Bertagnolli, Emmerich
    Free-Standing Magnetic Nanopillars for 3D Nanomagnet Logic2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 22, p. 20254-20260Article in journal (Refereed)
    Abstract [en]

    Nanomagnet logic (NML) is a relatively new computation technology that uses arrays of shape-controlled nanomagnets to enable digital processing. Currently, conventional resist-based lithographic processes limit the design of NML circuitry to planar nanostructures with homogeneous thicknesses. Here, we demonstrate the focused electron beam induced deposition of Fe-based nanomaterial for magnetic in-plane nanowires and out-of-plane nanopillars. Three-dimensional (3D) NML was achieved based on the magnetic coupling between nanowires and nanopillars in a 3D array. Additionally, the same Fe-based nanomaterial was used to produce tilt-corrected high-aspect-ratio probes for the accurate magnetic force microscopy (MFM) analysis of the fabricated 3D NML gate arrays. The interpretation of the MFM measurements was supported by magnetic simulations using the Object Oriented MicroMagnetic Framework. Introducing vertical out-of-plane nanopillars not only increases the packing density of 3D NML but also introduces an extra magnetic degree of freedom, offering a new approach to input/output and processing functionalities in nanomagnetic computing.

  • 17.
    Gustafsson, Simon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strategies for Tailoring the Pore-Size Distribution of Virus Retention Filter Papers2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 22, p. 13759-13767Article in journal (Refereed)
    Abstract [en]

    The goal of this work is to demonstrate how the pore-size distribution of the nanocellulose-based virus-retentive filter can be tailored. The filter paper was produced using cellulose nanofibers derived from Cladophora sp. green algae using the hot-press drying at varying drying temperatures. The produced filters were characterized using scanning electron microscopy, atomic force microscopy, and N2 gas sorption analysis. Further, hydraulic permeability and retention efficiency toward surrogate 20 nm model particles (fluorescent carboxylate-modified polystyrene spheres) were assessed. It was shown that by controlling the rate of water evaporation during hot-press drying the pore-size distribution can be precisely tailored in the region between 10 and 25 nm. The mechanism of pore formation and critical parameters are discussed in detail. The results are highly valuable for development of advanced separation media, especially for virus-retentive size-exclusion filtration.

  • 18. Ha Minh, Tan
    Minh Ngoc, Trinh (Contributor)
    Nguyen, Hugo (Contributor)
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Nguyen Duc, Hoa (Contributor)
    Hanoi University of Science and Technology.
    Duy, Nguyen Van
    Hanoi University of Science and Technology.
    Hieu, Nguyen Van
    Hanoi University of Science and Technology.
    Novel self-heated gas sensors using on-chip networked nanowires with ultralow power consumption2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 7, p. 6153-6162Article in journal (Refereed)
    Abstract [en]

    The length of single crystalline nanowires (NWs) offers aperfect pathway for electron transfer, while the small diameter of the NWshampers thermal losses to tje environment, substrate, and metal electrodes.Therefore, Joule self-heating effect is nearly ideal for operating NW gassensors at ultralow power consumption, without additional heaters. Therealization of the self-heated NW sensors using the “pick and place”approach is complex, hardly reproducible, low yield, and not applicable formass production. Here, we present the sensing capability of the self-heatednetworked SnO2 NWs effectively prepared by on-chip growth. Ourdeveloped self-heated sensors exhibit a good response of 25.6 to 2.5 ppmNO2 gas, while the response to 500 ppm H2, 100 ppm NH3, 100 ppm H2S,and 500 ppm C2H5OH is very low, indicating the good selectivity of thesensors to NO2 gas. Furthermore, the detection limit is very low, down to 82parts-per-trillion. As-obtained sensing performance under self-heating modeis nearly identical to that under external heating mode. While the power consumption under self-heating mode is extremely low,around hundreds of icrowatts, as scaled-down the size of the electrode is below 10 μm. The selectivity of the sensors can becontrolled simply by tuning the loading power that enables simple detection of NO2 in mixed gases. Remarkable performancetogether with a significantly facile fabrication process of the present sensors enhances the potential application of NW sensors innext generation technologies such as electronic noses, the Internet of Things, and smartphone sensing.

  • 19.
    Hao, Yan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Saygili, Yasemin
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, Stn 6, CH-1015 Lausanne, Switzerland..
    Cong, Jiayan
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, Appl Phys Chem, Teknikringen 30, SE-10044 Stockholm, Sweden..
    Eriksson, Anna
    Yang, Wenxing
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Zhang, Jinbao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Polanski, Enrico
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, Stn 6, CH-1015 Lausanne, Switzerland..
    Nonomura, Kazuteru
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, Stn 6, CH-1015 Lausanne, Switzerland..
    Zakeeruddin, Shaik Mohammed
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, Stn 6, CH-1015 Lausanne, Switzerland.;King Abdulaziz Univ, CEAMR, Jeddah 21589, Saudi Arabia..
    Gratzel, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, Stn 6, CH-1015 Lausanne, Switzerland..
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, Stn 6, CH-1015 Lausanne, Switzerland.;King Abdulaziz Univ, CEAMR, Jeddah 21589, Saudi Arabia..
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Novel Blue Organic Dye for Dye-Sensitized Solar Cells Achieving High Efficiency in Cobalt-Based Electrolytes and by Co-Sensitization2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 48, p. 32797-32804Article in journal (Refereed)
    Abstract [en]

    Blue and green dyes as well as NIR-absorbing dyes have attracted great interest because of their excellent ability of absorbing the incident photons in the red and near-infrared range region. A novel blue D-pi-A dye (Dyenamo Blue), based on the diketopyrrolopyrrole (DPP)-core, has been designed and synthesized. Assembled with the cobalt bipyridine-based electrolytes, the device with Dyenamo Blue achieved a satisfying efficiency of 7.3% under one sun (AM1.5 G). The co-sensitization strategy was further applied on this blue organic dye together with a red D-pi-A dye (D35). The successful co-sensitization outperformed a panchromatic light absorption and improved the photocurrent density; this in addition to the open-circuit potential result in an efficiency of 8.7%. The extended absorption of the sensitization and the slower recombination reaction between the blue dye and TiO2 surface inhibited by the additional red sensitizer could be the two main reasons for the higher performance. In conclusion, from the results, the highly efficient cobalt-based DSSCs could be achieved with the co-sensitization between red and blue D-pi-A organic dyes with a proper design, which showed us the possibility of applying this strategy for future high-performance solar cells.

  • 20. Hoshian, Sasha
    et al.
    Jokinen, Ville
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Ras, Robin H. A.
    Franssila, Sami
    Amplified and Localized Photoswitching of TiO2 by Micro- and Nanostructuring2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 28, p. 15593-15599Article in journal (Refereed)
    Abstract [en]

    Fast photoswitching of wetting properties is important for the development of micro/nanofluidic systems and lab-on-a-chip devices. Here, we show how structuring the surface amplifies photoswitching properties. Atomic layer-deposited titanium dioxide (TiO2) has phototunable hydrophilic properties due to its surface chemistry, but microscale overhang pillars and additional nanoscale topography can override the chemistry and make the surface sup erhydrophobic. Three switching processes are achieved simply by controlling the UV exposure time: from (1) rolling superhydrophobic to sticky superhydrophobic (Cassie-Baxter to Wenzel), (2) sup erhydrophobic to hydrophilic, and (3) superhydrophobic to superhydrophilic after 1, 5, and 10 min of UV exposure, respectively. We report the fastest reversible switching to date: 1 min of UV exposure is enough to promote a rolling-to-sticky transition, and mild heating (30 min at 60 degrees C) is sufficient for recovery. This performance is caused by a combination of the photoswitching properties of TiO2, the micropillar overhang geometry, and surface nanostructuring. We demonstrate that the switching also can be performed locally by introducing microwriting under a water droplet.

  • 21.
    Hultqvist, Adam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Aitola, Kerttu
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Sveinbjörnsson, Kári
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Saki, Zahra
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Sharif Univ Technol, Tehran, Iran.
    Larsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Johansson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Atomic Layer Deposition of Electron Selective SnOx and ZnO Films on Mixed Halide Perovskite: Compatibility and Performance2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 35, p. 29707-29716Article in journal (Refereed)
    Abstract [en]

    The compatibility of atomic layer deposition directly onto the mixed halide perovskite formamidinium lead iodide:methylammonium lead bromide (CH(NH2)(2), CH3NH3)Pb(I,Br)(3) (FAPbI(3):MAPbBr(3)) perovskite films is investigated by exposing the perovskite films to the full or partial atomic layer deposition processes for the electron selective layer candidates ZnO and SnOx. Exposing the samples to the heat, the vacuum, and even the counter reactant of H2O of the atomic layer deposition processes does not appear to alter the perovskite films in terms of crystallinity, but the choice of metal precursor is found to be critical. The Zn precursor Zn(C2H5)(2) either by itself or in combination with H2O during the ZnO atomic layer deposition (ALD) process is found to enhance the decomposition of the bulk of the perovskite film into PbI2 without even forming ZnO. In contrast, the Sn precursor Sn(N(CH3)(2))(4) does not seem to degrade the bulk of the perovskite film, and conformal SnOx films can successfully be grown on top of it using atomic layer deposition. Using this SnOx film as the electron selective layer in inverted perovskite solar cells results in a lower power conversion efficiency of 3.4% than the 8.4% for the reference devices using phenyl-C-70-butyric acid methyl ester. However, the devices with SnOx show strong hysteresis and can be pushed to an efficiency of 7.8% after biasing treatments. Still, these cells lacks both open circuit voltage and fill factor compared to the references, especially when thicker SnOx films are used. Upon further investigation, a possible cause of these losses could be that the perovskite/SnOx interface is not ideal and more specifically found to be rich in Sn, O, and halides, which is probably a result of the nucleation during the SnOx growth and which might introduce barriers or alter the band alignment for the transport of charge carriers.

  • 22.
    Jena, Naresh K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Araujo, Rafael Barros Neves de
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Shukla, Vivekanand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH.
    Borophane as a Benchmate of Graphene: A Potential 2D Material for Anode of Li and Na-Ion Batteries2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 19, p. 16148-16158Article in journal (Refereed)
    Abstract [en]

    Borophene, single atomic-layer sheet of boron (Science 2015, 350, 1513), is a rather new entrant into the burgeoning class of 2D materials. Borophene exhibits anisotropic metallic properties whereas its hydrogenated counterpart borophane is reported to be a gapless Dirac material lying on the same bench with the celebrated graphene. Interestingly, this transition of borophane also rendered stability to it considering the fact that borophene was synthesized under ultrahigh vacuum conditions on a metallic (Ag) substrate. On the basis of first-principles density functional theory computations, we have investigated the possibilities of borophane as a potential Li/Na-ion battery anode material. We obtained a binding energy of -2.58 (-1.08 eV) eV for Li (Na)-adatom on borophane and Bader charge analysis revealed that Li(Na) atom exists in Li+(Na+) state. Further, on binding with Li/Na, borophane exhibited metallic properties as evidenced by the electronic band structure. We found that diffusion pathways for Li/Na on the borophane surface are anisotropic with x direction being the favorable one with a barrier of 0.27 and 0.09 eV, respectively. While assessing the Li-ion anode performance, we estimated that the maximum Li content is Li0.445B2H2, which gives rises to a material with a maximum theoretical specific capacity of 504 mAh/g together with an average voltage of 0.43 V versus Li/Li+. Likewise, for Na-ion the maximum theoretical capacity and average voltage were estimated to be 504 mAh/g and 0.03 V versus Na/Na+, respectively. These findings unambiguously suggest that borophane can be a potential addition to the map of Li and Na-ion anode materials and can rival some of the recently reported 2D materials including graphene.

  • 23.
    Jeong, Seung Hee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Cruz, Javier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Chen, Si
    Chalmers, Dept Microtechnol & Nanosci MC2, Kemivagen 9, SE-41296 Gothenburg, Sweden.
    Gravier, Laurent
    Univ Appl Sci & Arts Western Switzerland, Inst Micro & Nano Tech, CH-1401 Yverdon, Switzerland.
    Liu, Johan
    Chalmers, Dept Microtechnol & Nanosci MC2, Kemivagen 9, SE-41296 Gothenburg, Sweden.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stretchable thermoelectric generators metallized with liquid alloy2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 18, p. 15791-15797Article in journal (Refereed)
    Abstract [en]

    Conventional thermoelectric generators (TEGs) are normally hard, rigid, and flat. However, most objects have curvy surfaces, which require soft and even stretchable TEGs for maximizing efficiency of thermal energy harvesting. Here, soft and stretchable TEGs using conventional rigid Bi2Te3 pellets metallized with a liquid alloy is reported. The fabrication is implemented by means of a tailored layer-by-layer fabrication process. The STEGs exhibit an output power density of 40.6 mu W/cm(2) at room temperature. The STEGs are operational after being mechanically stretched-and-released more than 1000 times, thanks to the compliant contact between the liquid alloy interconnects and the rigid pellets. The demonstrated interconnect scheme will provide a new route to the development of soft and stretchable energy-harvesting avenues for a variety of emerging electronic applications.

  • 24.
    Li, Min
    et al.
    Beihang Univ, Dept Phys, Minist Educ, Key Lab Micronano Measurement Manipulat & Phys, Beijing 100191, Peoples R China.;Taishan Univ, Sch Phys & Elect Engn, Tai An 271021, Shandong, Peoples R China..
    Zhang, Junying
    Beihang Univ, Dept Phys, Minist Educ, Key Lab Micronano Measurement Manipulat & Phys, Beijing 100191, Peoples R China..
    Gao, Hong
    Beihang Univ, Dept Phys, Minist Educ, Key Lab Micronano Measurement Manipulat & Phys, Beijing 100191, Peoples R China..
    Li, Feng
    Taishan Univ, Sch Phys & Elect Engn, Tai An 271021, Shandong, Peoples R China..
    Lindquist, Sten-Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wu, Nianqiang
    W Virginia Univ, Dept Mech & Aerosp Engn, Morgantown, WV 26506 USA..
    Wang, Rongming
    Univ Sci & Technol Beijing, Sch Math & Phys, Beijing 100083, Peoples R China..
    Microsized BiOCl Square Nanosheets as Ultraviolet Photodetectors and Photocatalysts2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 10, p. 6662-6668Article in journal (Refereed)
    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.

  • 25.
    Lindgren, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Niedzicki, Leszek
    Warsaw Univ Technol, Fac Chem, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Marcinek, Marek
    Warsaw Univ Technol, Fac Chem, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    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.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    SEI Formation and Interfacial Stability of a Si Electrode in a LiTDI-Salt Based Electrolyte with FEC and VC Additives for Li-Ion Batteries2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 24, p. 15758-15766Article in journal (Refereed)
    Abstract [en]

    An electrolyte based on the new salt, lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI), is evaluated in combination with nano-Si composite electrodes for potential use in Li-ion batteries. The additives fluoroethylene carbonate (FEC) and vinylene carbonate (VC) are also added to the electrolyte to enable an efficient SEI formation. By employing hard X-ray photoelectron spectroscopy (HAXPES), the SEI formation and the development of the active material is probed during the first 100 cycles. With this electrolyte formulation, the Si electrode can cycle at 1200 mAh g(-1) for more than 100 cycles at a coulombic efficiency of 99%. With extended cycling, a decrease in Si particle size is observed as well as an increase in silicon oxide amount. As opposed to LiPF6 based electrolytes, this electrolyte or its decomposition products has no side reactions with the active Si material. The present results further acknowledge the positive effects of SEI forming additives. It is suggested that polycarbonates and a high LiF content are favorable components in the SEI over other kinds of carbonates formed by ethylene carbonate (EC) and dimethyl carbonate (DMC) decomposition. This work thus confirms that LiTDI in combination with the investigated additives is a promising salt for Si electrodes in future Li-ion batteries.

  • 26.
    Liu, Chenjuan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Carboni, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Hedman, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    On the Stability of NaO2 in Na–O2 Batteries2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 16, p. 13534-13541Article in journal (Refereed)
    Abstract [en]

    Na–O2 batteries are regarded as promising candidates for energy storage. They have higher energy efficiency, rate capability, and chemical reversibility than Li–O2 batteries; in addition, sodium is cheaper and more abundant compared to lithium. However, inconsistent observations and instability of discharge products have inhibited the understanding of the working mechanism of this technology. In this work, we have investigated a number of factors that influence the stability of the discharge products. By means of in operando powder X-ray diffraction study, the influence of oxygen, sodium anode, salt, solvent, and carbon cathode were investigated. The Na metal anode and an ether-based solvent are the main factors that lead to the instability and decomposition of NaO2 in the cell environment. This fundamental insight brings new information on the working mechanism of Na–O2 batteries.

  • 27.
    Liu, Yanyan
    et al.
    Royal Inst Technol, Dept Energy Technol, SE-10044 Stockholm, Sweden..
    Fan, Liangdong
    Shenzhen Univ, Coll Chem & Environm Engn, Shenzhen Key Lab New Lithium Ion Batteries & Meso, Shenzhen 518060, Guangdong, Peoples R China..
    Cai, Yixiao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Natl Univ Singapore, NUS Environm Res Inst, 1 Create Way, Singapore 138602, Singapore..
    Zhang, Wei
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Wang, Baoyuan
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Zhu, Bin
    Royal Inst Technol, Dept Energy Technol, SE-10044 Stockholm, Sweden.;Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Superionic Conductivity of Sm3+, Pr3+, and Nd3+ Triple-Doped Ceria through Bulk and Surface Two-Step Doping Approach2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 28, p. 23614-23623Article in journal (Refereed)
    Abstract [en]

    Sufficiently high oxygen ion conductivity of electrolyte is critical for good performance of low-temperature solid oxide fuel cells (LT-SOFCs). Notably, material conductivity, reliability, and manufacturing cost are the major barriers hindering LT-SOFC commercialization. Generally, surface properties control the physical and chemical functionalities of materials. Hereby, we report a Sm3+, Pr3+, and Nd3+ triple-doped ceria, exhibiting the highest ionic conductivity among reported doped-ceria oxides, 0.125 S cm(-1) at 600 degrees C. It was designed using a two-step wet-chemical coprecipitation method to realize a desired doping for Sm3+ at the bulk and Pr3+/Nd3+ at surface domains (abbreviated as PNSDC). The redox couple Pr3+ Pr4+ contributes to the extraordinary ionic conductivity. Moreover, the mechanism for ionic conductivity enhancement is demonstrated. The above findings reveal that a joint bulk and surface doping methodology for ceria is a feasible approach to develop new oxide-ion conductors with high impacts on advanced LT-SOFCs.

  • 28.
    Luo, Jun
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Martinez-Casado, Francisco Javier
    Max IV Laboratory, Lund University.
    Balmes, Olivier
    Max IV Laboratory, Lund University.
    Yang, Jiaojiao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    In-situ Synchrotron X-ray Diffraction Analysis of the Setting Process of Brushite Cement: Reaction and Crystal Growth2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 41, p. 36392-36399Article in journal (Refereed)
    Abstract [en]

    Brushite cements are fast self-setting materials that can be used as bone substitute materials. Although tracing their fast setting process is a challenge, it is important for the understanding of the same, which in turn is important for the material’s further development and use in the clinics. In this study, the setting rate, phase formation, and crystal growth of brushite cements were quantitatively studied by in situ synchrotron powder X-ray diffraction (SXRD) on a time scale of seconds. The influence of reactant ratios and a retardant (citric acid) on the setting reaction were analyzed. To complement the in situ investigations, scanning electron microscopy was carried out for ex situ morphological evolution of crystals. The initial reaction followed a four-step process, including a fast nucleation induction period, nucleation, crystal growth, and completion of the setting. The brushite crystal size grew up to the micro scale within 1 min, and the brushite content increased linearly after the nucleation until all monocalcium phosphate monohydrate (MCPM; Ca(H2PO4)2·H2O) had dissolved within minutes, followed by a slow increase until the end of the monitoring. By adjusting the MCPM to the β-tricalcium phosphate (β-TCP, β-Ca3(PO4)2) ratio in the starting powders, the brushite/monetite ratio in the cements could be modified. In the presence of citric acid, the formation of brushite nuclei was not significantly retarded, whereas the increase in brushite content and the growth of crystal size were effectively hindered. The amount of monetite also increased by adding citric acid. This is the first time that the brushite setting process has been characterized in the first seconds and minutes of the reaction by SXRD.

  • 29.
    Ma, Yue
    et al.
    Northwestern Polytech Univ, Sch Mat Sci & Engn, State Key Lab Solidificat Proc, Ctr Nano Energy Mat, Xian 710072, Shaanxi, Peoples R China.
    Tai, Cheuk-Wai
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Li, Shaowen
    Northwestern Polytech Univ, Sch Mat Sci & Engn, State Key Lab Solidificat Proc, Ctr Nano Energy Mat, Xian 710072, Shaanxi, Peoples R China.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wei, Bingqing
    Univ Delaware, Dept Mech Engn, Newark, DE 19716 USA.
    Multiscale Interfacial Strategy to Engineer Mixed Metal-Oxide Anodes toward Enhanced Cycling Efficiency2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 23, p. 20095-20105Article in journal (Refereed)
    Abstract [en]

    Interconnected macro/mesoporous structures of mixed metal oxide (MMO) are developed on nickel foam as freestanding anodes for Li-ion batteries. The sustainable production is realized via a wet chemical etching process with bio-friendly chemicals. By means of divalent iron doping during an in situ recrystallization process, the as-developed MMO anodes exhibit enhanced levels of cycling efficiency. Furthermore, this atomic-scale modification coherently synergizes with the encapsulation layer across a micrometer scale. During this step, we develop a quasi-gel-state tri-copolymer, i.e., F127-resorcinol-melamine, as the N-doped carbon source to regulate the interfacial chemistry of the MMO electrodes. Electrochemical tests of the modified FexN1-xO@NC-NiF anode in both half-cell and full-cell configurations unravel the favorable suppression of the irreversible capacity loss and satisfactory cyclability at the high rates. This study highlights a proof-of-concept modification strategy across multiple scales to govern the interfacial chemical process of the electrodes toward better reversibility.

  • 30.
    Maibach, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Jeschull, Fabian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    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.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Surface Layer Evolution on Graphite During Electrochemical Sodium-tetraglyme Co-intercalation2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 14, p. 12373-12381Article in journal (Refereed)
    Abstract [en]

    One obstacle in sodium ion batteries is the lack of suitable anode materials. As recently shown, the most common anode material of the state of the art lithium ion batteries, graphite, can be used for sodium ion storage as well, if ether based electrolyte solvents are used. These solvents cointercalate with the sodium ions leading to the highly reversible formation of ternary graphite intercalation compounds (t-GIC). In order for the solvent cointercalation to work efficiently, it is expected that only a very thin surface layer forms during electrochemical cycling. In this article, we therefore present the first dedicated study of the surface layer evolution on t-QICs using soft X-ray photoelectron spectroscopy. This technique with its inherent high surface sensitivity and low probing depth is an ideal tool to study the underlying interfacial reactions during the sodiation and desodiation of graphite. In this report, we apply this approach to graphite composite electrodes cycled in Na half cells with a 1 M sodium bis(fluorosulfonyl)imide/tetraethylene glycol dimethyl ether (NaFSI/TEG-DME) electrolyte. We have found a surface layer on the cycled electrodes, mainly composed of salt decomposition products and hydrocarbons, in line with irreversible capacity losses observed in the electrochemical cycling. Although this surface layer does not seem to block cointercalation completely, it seems to affect its efficiency resulting in a low Coulombic efficiency of the studied battery system.

  • 31.
    Makaraviciute, Asta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Xu, Xingxing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zhang, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Systematic approach to the development of microfabricated biosensors: relationship between the gold surface pretreatment and thiolated molecule binding2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 31, p. 26610-26621Article in journal (Refereed)
    Abstract [en]

    Despite the increasing popularity of microfabricated biosensors due to advances in technologic and surface functionalization strategies, their successful implementation is partially inhibited by the lack of consistency in their analytical characteristics. One of the main causes for the discrepancies is the absence of a systematic and comprehensive approach to surface functionalization. In this article microfabricated gold electrodes aimed at biosensor development have been systematically characterized in terms of surface pretreatment, thiolated molecule binding, and reproducibility by means of X-ray photoelectron scattering (XPS) and cyclic voltammetry (CV). It has been shown that after SU-8 photolithography gold surfaces were markedly contaminated, which decreased the effective surface area and surface coverage of a model molecule mercaptohexanol (MCH). Three surface pretreatment methods compatible with microfabricated devices were compared. The investigated methods were (i) cyclic voltammetry in dilute H2SO4, (ii) gentle basic piranha followed by linear sweep voltammetry in dilute KOH, and (iii) oxygen plasma treatment followed by incubation in ethanol. It was shown that all three methods significantly decreased the contamination and increased MCH surface coverage. Most importantly, it was also revealed that surface pretreatments may induce structural changes to the gold surfaces. Accordingly, these alterations influence the characteristics of MCH functionalization.

  • 32.
    Mao, Fang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Taher, Mamoun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Kryshtal, Oleksandr
    AGH Univ Sci & Technol, Int Ctr Electron Microscopy Mat Sci, Al A Mickiewicza 30, PL-30059 Krakow, Poland.;AGH Univ Sci & Technol, Fac Met Engn & Ind Comp Sci, Al A Mickiewicza 30, PL-30059 Krakow, Poland..
    Kruk, Adam
    AGH Univ Sci & Technol, Int Ctr Electron Microscopy Mat Sci, Al A Mickiewicza 30, PL-30059 Krakow, Poland.;AGH Univ Sci & Technol, Fac Met Engn & Ind Comp Sci, Al A Mickiewicza 30, PL-30059 Krakow, Poland..
    Czyrska-Filemonowicz, Aleksandra
    AGH Univ Sci & Technol, Int Ctr Electron Microscopy Mat Sci, Al A Mickiewicza 30, PL-30059 Krakow, Poland.;AGH Univ Sci & Technol, Fac Met Engn & Ind Comp Sci, Al A Mickiewicza 30, PL-30059 Krakow, Poland..
    Ottosson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Andersson, Anna M.
    ABB AB, Corp Res, SE-72178 Vasteras, Sweden..
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Combinatorial Study of Gradient Ag-Al Thin Films: Microstructure, Phase Formation, Mechanical and Electrical Properties2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 44, p. 30635-30643Article in journal (Refereed)
    Abstract [en]

    A combinatorial approach is applied to rapidly deposit and screen Ag-Al thin films-to evaluate the mechanical, tribological, and electrical properties as a function of chemical composition. Ag-Al thin films with large continuous composition gradients (6-60 atom % Al) were deposited by a custom-designed combinatorial magnetron sputtering system. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning and transmission electron microscopy (SEM and TEM), X-ray photoelectron spectroscopy (XPS), nanoindentation, and four-point electrical resistance screening were employed to characterize the chemical composition, structure, and physical properties of the films in a time-efficient way. For low Al contents (<13 atom %), a highly (111)-textured fcc phase was formed. At higher Al contents, a (002)-textured hcp solid solution phase was formed followed by a fcc phase in the most At-rich regions. No indication of a mu phase was observed. The Ag-Al films with fcc-Ag matrix is prone to adhesive material transfer leading to a high friction coefficient (>1) and adhesive wear, similar to the behavior of pure Ag. In contrast, the hexagonal solid solution phase (from ca. 15 atom %Al) exhibited dramatically reduced friction coefficients (about 15% of that of the fcc phase) and dramatically reduced adhesive wear when tested against the pure Ag counter surface. The increase in contact resistance of the Ag Al films is limited to only 50% higher than a pure Ag reference sample at the low friction and low wear region (19-27 atom %). This suggests that a hcp Ag Al alloy can have a potential use in sliding electrical contact applications and in the future will replace pure Ag in specific electromechanical applications.

  • 33.
    Nisar, Jawat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Topalian, Zareh
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    De Sarkar, Abir
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    TiO2‑Based Gas Sensor: A Possible Application to SO22013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 17, p. 8516-8522Article in journal (Refereed)
    Abstract [en]

    Fixation of SO2 molecules on anatase TiO2 surfaceswith defects have been investigated by first-principles densityfunctional theory (DFT) calculations and in situ Fourier transforminfrared (FTIR) surface spectroscopy on porous TiO2 films. Intrinsicoxygen-vacancy defects, which are formed on TiO2(001) andTiO2(101) surfaces by ultraviolet (UV) light irradiation and atelevated temperatures, are found to be most effective in anchoringthe SO2 gas molecules to the TiO2 surfaces. Both TiO2(101) andTiO2(001) surfaces with oxygen vacancies are found to exhibit higherSO2 adsorption energies in the DFT calculations. The adsorptionmechanism of SO2 is explained on the basis of electronic structure,charge transfer between the molecule and the surface, and the oxidation state of the adsorbed molecule. The theoretical findingsare corroborated by FTIR experiments. Moreover, the (001) surface with oxygen vacancies is found to bind SO2 gas moleculesmore strongly, as compared to the (101) surface. Higher concentration of oxygen vacancies on the TiO2 surfaces is found tosignificantly increase the adsorption energy. The results shed new insight into the sensing properties of TiO2-based gas sensors

  • 34.
    Norrbo, Isabella
    et al.
    Univ Turku, Dept Chem, FI-20014 Turku, Finland..
    Gluchowski, Pawel
    Polish Acad Sci, Inst Low Temp & Struct Res, PL-50422 Wroclaw, Poland..
    Hyppanen, Iko
    Univ Turku, Dept Chem, FI-20014 Turku, Finland..
    Laihinen, Tero
    Univ Turku, Dept Chem, FI-20014 Turku, Finland.;Univ Turku Grad Sch UTUGS, Doctoral Programme Phys & Chem Sci, FI-20014 Turku, Finland..
    Laukkanen, Pekka
    Univ Turku, Dept Phys & Astron, FI-20014 Turku, Finland..
    Makela, Jaakko
    Univ Turku, Dept Phys & Astron, FI-20014 Turku, Finland.;Univ Turku Grad Sch UTUGS, Doctoral Programme Phys & Chem Sci, FI-20014 Turku, Finland..
    Mamedov, Fikret
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Santos, Hellen S.
    Univ Turku, Dept Chem, FI-20014 Turku, Finland.;Univ Turku Grad Sch UTUGS, Doctoral Programme Phys & Chem Sci, FI-20014 Turku, Finland..
    Sinkkonen, Jari
    Univ Turku, Dept Chem, FI-20014 Turku, Finland..
    Tuomisto, Minnea
    Univ Turku, Dept Chem, FI-20014 Turku, Finland.;Univ Turku Grad Sch UTUGS, Doctoral Programme Phys & Chem Sci, FI-20014 Turku, Finland..
    Viinikanoja, Antti
    Univ Turku, Dept Chem, FI-20014 Turku, Finland..
    Lastusaari, Mika
    Univ Turku, Dept Chem, FI-20014 Turku, Finland.;Univ Turku, Ctr Mat & Surfaces, FI-20014 Turku, Finland..
    Mechanisms of Tenebrescence and Persistent Luminescence in Synthetic Hackmanite Na8Al6Si6O24(Cl,S)(2)2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 18, p. 11592-11602Article in journal (Refereed)
    Abstract [en]

    Synthetic hackmanites, Na8Al6Si6O24(Cl,S)(2), showing efficient purple tenebrescence and blue/white persistent luminescence were studied using different spectroscopic techniques to obtain a quantified view on the storage and release of optical energy in these materials. The persistent luminescence emitter was identified as impurity Ti3+ originating from the precursor materials used in the synthesis, and the energy storage for persistent luminescence was postulated to take place in oxygen vacancies within the aluminosilicate framework. Tenebrescence, on the other hand, was observed to function within the Na-4(Cl,S) entities located in the cavities of the aluminosilicate framework. The mechanism of persistent luminescence and tenebrescence in hackmanite is presented for the first time.

  • 35.
    Nyström, Lina
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Alvarez-Asencio, Ruben
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Surface & Corros Sci, SE-10044 Stockholm, Sweden.;IMDEA Nanosci, Inst Adv Studies, Madrid 28049, Spain..
    Frenning, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Saunders, Brian R.
    Univ Manchester, Sch Mat, MSS Tower, Manchester M13 9PL, Lancs, England..
    Rutland, Mark W.
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Surface & Corros Sci, SE-10044 Stockholm, Sweden.;SP Tech Res Inst Sweden, SP Chem Mat & Surfaces, SE-11486 Stockholm, Sweden..
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Electrostatic Swelling Transitions in Surface-Bound Microgels2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 40, p. 27129-27139Article in journal (Refereed)
    Abstract [en]

    Herein, electrostatic swelling transitions of poly (ethyl acrylate-co-methacrylic acid) microgels covalently bound to silica surfaces are investigated. Confined at a solid surface, microgel swelling is anisotropically hindered and the structure is flattened to an extent dictated by pH and microgel composition. Microgel deformation under applied load is also shown to depend on microgel charge density, with the highest deformation observed at intermediate charge densities. Two modes of microgel deformation under load were observed, one elastic and one viscoelastic, related to polymer strand deformation and displacement of trapped water, respectively. Results on polymer strand dynamics reveal that the microgels are highly dynamic, as the number of strand-tip interaction points increases 4-fold during a 10 s contact time. Furthermore, finite element modeling captures these effects qualitatively and shows that stress propagation in the microgel network decays locally at the rim of contact with a solid interface or close to the tip probe. Taken together, the results demonstrate a delicate interplay between the surface and microgel which determines the structure and nanomechanical properties of the latter and needs to be controlled in applications of systems such as pH-responsive surface coatings in biomaterials.

  • 36.
    Oommen, Oommen Podiyan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Tampere Univ Technol, BioMediTech Inst Biosci & Med Technol, Bioengn & Nanomed Grp, Tampere 33520, Finland..
    Duehrkop, Claudia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Nilsson, Bo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Varghese, Oommen P.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Multifunctional Hyaluronic Acid and Chondroitin Sulfate Nanoparticles: Impact of Glycosaminoglycan Presentation on Receptor Mediated Cellular Uptake and Immune Activation2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 32, p. 20614-20624Article in journal (Refereed)
    Abstract [en]

    Hyaluronic acid (HA) and chondroitin sulfate (CS) polymers are extensively used for various biomedical applications, such as for tissue engineering, drug delivery, and gene delivery. Although both these biopolymers are known to target cell surface CD44 receptors, their relative cellular targeting properties and immune activation potential have never been evaluated. In this article, we present the synthesis and characterization of novel self assembled supramolecular HA and CS nanoparticles (NPs). These NPs were developed using fluorescein as a hydrophobic component that induced amphiphilicity in biopolymers and also efficiently stabilized anticancer drug doxorubicin (DOX) promoting a near zero-order drug release. The cellular uptake and cytotoxicity studies of these NPs in different human cancer lines, namely, human colorectal carcinoma cell line HCT116 and human breast cancer cell line MCF-7 demonstrated dose dependent cytotoxicity. Interestingly, both NPs showed CD44 dependent cellular uptake with the CS DOX NP displaying higher dose-dependent cytotoxicity than the HA DOX NP in different mammalian cells tested. Immunological evaluation of these nanocarriers in an ex vivo human whole blood model revealed that unlike unmodified polymers, the HA NP and CS NP surprisingly showed platelet aggregation and thrombin antithrombin complex formation at high concentrations (0.8 mg/mL). We also observed a clear difference in early- and late-stage complement activation (C3a and sC5b-9) with CS and CS NP triggering significant complement activation at high concentrations (0.08-0.8 mg/mL), unlike HA and HA NP. These results offer new insight into designing glycosaminoglycan-based NPs and understanding their hematological responses and targeting ability.

  • 37.
    Park, Byung-wook
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Pazoki, Meysam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Aitola, Kerttu
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Jeong, Seunghee
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Understanding Interfacial Charge Transfer between Metallic PEDOT Counter Electrodes and a Cobalt Redox Shuttle in Dye-Sensitized Solar Cells2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 3, p. 2074-2079Article in journal (Refereed)
    Abstract [en]

    Conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with iron(111) tris-p-toluenesulfonate (PEDOT:Tos) having metallic conductivity was coated onto fluorine-doped tin oxide (FTO) glass and plain glass substrates and used as a counter electrode (CE) in a dye-sensitized solar cell (DSC) with a [Co(bpy)(3)](3+/2+) complex redox shuttle. DSCs with PEDOT:Tos/glass CE yielded power conversion efficiencies (PCE) of 6.3%, similar to that of DSCs with platinized FTO glass CE (6.1%). The PEDOT:Tos-based counter electrodes had 5 to 10 times lower charge-transfer resistance than the Pt/FTO CE in DSCs, as analyzed by impedance spectroscopy. More detailed studies in symmetrical CE-CE cells showed that the PEDOT:Tos layers are nanoporous. Not all internal area can be used catalytically under solar cell conditions and effective charge-transfer resistance was similar to that of Pt/FTO.

  • 38.
    Qu, Hui-Ying
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Harbin Institute of Technology, School of Chemistry and Chemical Engineering, MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Arvizu, Miguel A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Cindemir, Umut
    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.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochemical Rejuvenation of Anodically Coloring Electrochromic Nickel Oxide Thin Films2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, no 9, p. 42420-42424Article in journal (Refereed)
    Abstract [en]

    Nickel oxide thin films are of major importance as anodically coloring components in electrochromic smart windows with applications in energy-efficient buildings. However, the optical performance of these films degrades upon extended electrochemical cycling, which has hampered their implementation. Here, we use a potentiostatic treatment to rejuvenate degraded nickel oxide thin films immersed in electrolytes of LiClO4 in propylene carbonate. Time-of-flight elastic recoil detection analysis provided unambiguous evidence that both Li+ ions and chlorine-based ions participate in the rejuvenation process. Our work provides new perspectives for developing ion-exchange-based devices embodying nickel oxide.

  • 39.
    Ren, Yi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Scragg, Jonathan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Larsen, Jes
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Evolution of Na-S(-O) compounds on the Cu2ZnSnS4 absorber surface and their effects on CdS thin film growth2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 28, p. 18600-18607Article in journal (Refereed)
    Abstract [en]

    Formation of Na-containing surface compounds is an important phenomenon in the Cu2ZnSnS4 (CZTS) quaternary material synthesis for solar cell applications. Still, identification of these compounds and the understanding of their potential influence on buffer layer growth and device performance are scarce. In this work, we discovered that the evolution of Na-S(-O) compounds on the CZTS surface substantially affect the solution/CZTS interface during the chemical bath deposition of CdS buffer film. We showed that Na2S negatively affects the growth of CdS, and that this compound is likely to form on the CZTS surface after annealing. It was also demonstrated that the Na2S compound can be oxidized to Na2SO4 by air exposure of the annealed CZTS surface or be removed using water dipping instead of the commonly used KCN etching process, resulting in significantly better quality of the CdS layer. Lastly, 6.5% CZTS solar cells were fabricated with air exposure treatment without incorporation of the KCN etching process. This work provides new insight into the growth of the CdS/CZTS interface for solar cell applications and opens new possibilities for improving likewise Cd-free buffer materials that are grown with a similar chemical bath deposition process.

  • 40. Roy-Mayhew, Joseph D.
    et al.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Aksay, Ilhan A.
    Functionalized Graphene Sheets as a Versatile Replacement for Platinum in Dye-Sensitized Solar Cells2012In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 4, no 5, p. 2794-2800Article in journal (Refereed)
    Abstract [en]

    Several techniques for fabricating functionalized graphene sheet (FGS) electrodes were tested for catalytic performance in dye-sensitized solar cells (DSSCs). By using ethyl cellulose as a sacrificial binder, and partially thermolyzing it, we were able to create electrodes which exhibited lower effective charge transfer resistance (<1 Omega cm(2)) than the thermally decomposed chloroplatinic acid electrodes traditionally used. This performance was achieved not only for the triiodide/iodide redox couple, but also for the two other major redox mediators used in DSSCs, based on cobalt and sulfur complexes, showing the versatility of the electrode. DSSCs using these FGS electrodes had efficiencies (eta) equal to or higher than those using thermally decomposed chloroplatinic acid electrodes in each of the three major redox mediators: I (eta(FGS) = 6.8%, eta(Pt) = 6.8%), Co (4.5%, 4.4%), S (3.5%, 2.0%). Through an analysis of the thermolysis of the binder and composite material, we determined that the high surface area of an electrode, as determined by nitrogen adsorption, is consistent with but not sufficient for high performing electrodes. Two other important considerations are that (i) enough residue remains in the composite to maintain structural stability and prevent restacking of FGSs upon the introduction of the solvent, and (ii) this residue must not disperse in the electrolyte.

  • 41.
    Rupp, Caroline J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Fed Santa Maria, Dept Fis, BR-97105900 Santa Maria, RS, Brazil..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Anversa, Jonas
    Univ Fed Santa Maria, Dept Fis, BR-97105900 Santa Maria, RS, Brazil.;Fac Merid, BR-99070220 Passo Fundo, RS, Brazil..
    Baierle, Rogerio J.
    Univ Fed Santa Maria, Dept Fis, BR-97105900 Santa Maria, RS, Brazil..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Rationalizing the Hydrogen and Oxygen Evolution Reaction Activity of Two-Dimensional Hydrogenated Silicene and Germanene2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 2, p. 1536-1544Article in journal (Refereed)
    Abstract [en]

    We have undertaken first-principles electronic structure calculations to show that the chemical functionalization of two-dimensional hydrogenated silicene (silicane) and germanene (germanane) can become a powerful tool to increase the photocatalytic water-splitting activity. Spin-polarized density functional theory within the GGA-PBE and HSE06 types of exchange correlation functionals has been used to obtain the structural, electronic, and optical properties of silicane and germanane functionalized with a series of nonmetals (N, P, and S), alkali metals (Li, Na, and K) and alkaline-earth metals (Mg and Ca). The surface-adsorbate interaction between the functionalized systems with H-2 and O-2 molecules that leads to envisaged hydrogen and oxygen evolution reaction activity has been determined.

  • 42.
    Shukla, Vivekanand
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Jena, Naresh K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Grigoriev, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH, Stockholm, Sweden.
    Prospects of Graphene-hBN Heterostructure Nanogap for DNA Sequencing2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 46, p. 39945-39952Article in journal (Refereed)
    Abstract [en]

    Recent advances in solid-state nano-device-based DNA sequencing are at the helm of the development of a new paradigm, commonly referred to as personalized medicines. Paying heed to a timely need for standardizing robust nanodevices for cheap, fast, and scalable DNA detection, in this article, the nanogap formed by the lateral heterostructure of graphene and hexagonal boron nitride (hBN) is explored as a potential architecture. These heterostructures have been realized experimentally, and our study boasts the idea that the passivation of the edge of the graphene electrode with hBN will solve many of practical problems, such as high reactivity of the graphene edge and difficulty in controlled engineering of the graphene edge structure, while retaining the nanogap setup as a useful nanodevice for sensing applications. Employing first-principle density-functional-theory-based nonequilibrium Greens function methods, we identify that the DNA building blocks, nucleobases, uniquely couple with the states of the nanogap, and the resulting induced states can be attributed as leaving a fingerprint of the DNA sequence in the computed current-voltage (I-V) characteristic. Two bias windows are put forward: lower (1-1.2 V) and higher (2.7-3 V), where unique identification of all four bases is possible from the current traces, although higher sensitivity is obtained at the higher voltage window. Our study can be a practical guide for experimentalists toward development of a nanodevice DNA sensor based on graphene-hBN heterostructures.

  • 43.
    Singh, Shalini
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Datta, Aritreyee
    Bose Inst, Dept Biophys, P-1-12 CIT Scheme 7 M, Kolkata 700054, India..
    Borro, Bruno C.
    Univ Copenhagen, Dept Pharm, DK-2100 Copenhagen, Denmark..
    Davoudi, Mina
    Lund Univ, Div Dermatol & Venereol, Dept Clin Sci, SE-22184 Lund, Sweden..
    Schmidtchen, Artur
    Lund Univ, Div Dermatol & Venereol, Dept Clin Sci, SE-22184 Lund, Sweden.;Nanyang Technol Univ, Lee Kong Chian Sch Med, 11 Mandalay Rd, Singapore 308232, Singapore.;Bispebjerg Hosp, Wound Healing Ctr, DK-2100 Copenhagen, Denmark..
    Bhunia, Anirban
    Bose Inst, Dept Biophys, P-1-12 CIT Scheme 7 M, Kolkata 700054, India..
    Malmsten, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Univ Copenhagen, Copenhagen, Denmark.
    Conformational Aspects of High Content Packing of Antimicrobial Peptides in Polymer Microgels2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 46, p. 40094-40106Article in journal (Refereed)
    Abstract [en]

    Successful use of microgels as delivery systems of antimicrobial peptides (AMPs) requires control of factors determining peptide loading and release to/from the microgels as well as of membrane interactions of both microgel particles and released peptides. Addressing these, we here investigate effects of microgel charge density and conformationally induced peptide amphiphilicity on AMP loading and release using detailed nuclear magnetic resonance (NMR) structural studies combined with ellipsometry, isothermal titration calorimetry, circular dichroism, and light scattering. In parallel, consequences of peptide loading and release for membrane interactions and antimicrobial effects were investigated. In doing so, poly(ethyl acrylate-co-methacrylic acid) microgels were found to incorporate the cationic AMPs EFK17a (EFKRIVQRIKDFLRNLV) and its partially D-amino acid-substituted variant EFK17da (E(dF)KR(dI)VQR(dI)KD(dF)LRNLV). Peptide incorporation was found to increase with increasing with microgel charge density and peptide amphiphilicity. After microgel incorporation, which appeared to occur preferentially in the microgel core, NMR showed EFK17a to form a helix with pronounced amphiphilicity, while EFK17da displayed a folded conformation, stabilized by a hydrophobic hub consisting of aromatic/aromatic and aliphatic/aromatic interactions, resulting in much lower amphiphilicity. Under wide ranges of peptide loading, the microgels displayed net negative z-potential. Such negatively charged microgels do not bind to, nor lyre, bacteria-mimicking membranes. Instead, membrane disruption in these systems is mediated largely by peptide release, which in turn is promoted at higher ionic strength and lower peptide amphiphilicity. Analogously, antimicrobial effects against Escherichia coli were found to be dictated by peptide release. Taken together, the findings show that peptide loading, packing, and release strongly affect the performance of microgels as AMP delivery systems, effects that can be tuned by (conformationally induced) peptide amphiphilicity and by microgel charge density.

  • 44.
    Sun, Bing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Paul Scherrer Inst, Electrochem Lab, Electrochem Energy Storage Sect, CH-5232 Villigen, Switzerland.
    Asfaw, Habtom Desta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Imperial Coll London, Dept Chem, London SW7 2AZ, England.
    Rehnlund, David
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    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.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Towards Solid-State 3D-Microbatteries using Functionalized Polycarbonate-based Polymer Electrolytes2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 3, p. 2407-2413Article in journal (Refereed)
    Abstract [en]

    3D-microbatteries (3D-MBs) impose new demands for theselection, fabrication and compatibility of the different battery components, notleast the electrolytes. Herein, solid polymer electrolytes (SPEs) based on poly(trimethylene carbonate) (PTMC) have been implemented in 3D-MB systems. 3D electrodes of two different architectures, LiFePO4-coated carbon foams and Cu2O-coated Cu nanopillars, have been coated with SPEs and used in Li-cells. Functionalized PTMC with hydroxyl end groups was found to enable uniform and well-covering coatings on LiFePO4-coated carbon foams, although the cell cycling performance was limited by the large SPE resistance. By employing a SPE prepared from a copolymer of TMC and caprolactone (CL), with higher ionic conductivity, Li-cells composed of Cu2O-coated Cu nanopillars were constructed and tested both at room temperature and 60 °C. The footprint areal capacity of the cells was ca. 0.02 mAh cm-2 for an area gain factor (AF) of 2.5, and 0.2 mAh cm-2 for a relatively dense nanopillar-array (AF=25) at a current density of 0.008 mA cm-2at ambient temperature (22±1 °C). These results provide new routes towards the realization of all-solid-state 3D-MBs.

  • 45.
    Sun, Rui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhang, Peng
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden.
    Bajnóczi, Éva G
    Neagu, Alexandra
    Tai, Cheuk-Wai
    Persson, Ingmar
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Cheung, Ocean
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Amorphous Calcium Carbonate Constructed from Nanoparticle Aggregates with Unprecedented Surface Area and Mesoporosity2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 25, p. 21556-21564Article in journal (Refereed)
    Abstract [en]

    Amorphous calcium carbonate (ACC), with the highest reported specific surface area of all current forms of calcium carbonate (over 350 m2 g-1), was synthesized using a surfactant-free, one-pot method. Electron microscopy, helium pycnometry, and nitrogen sorption analysis revealed that this highly mesoporous ACC, with a pore volume of ∼0.86 cm3 g-1 and a pore-size distribution centered at 8-9 nm, is constructed from aggregated ACC nanoparticles with an estimated average diameter of 7.3 nm. The porous ACC remained amorphous and retained its high porosity for over 3 weeks under semi-air-tight storage conditions. Powder X-ray diffraction, large-angle X-ray scattering, infrared spectroscopy, and electron diffraction exposed that the porous ACC did not resemble any of the known CaCO3 structures. The atomic order of porous ACC diminished at interatomic distances over 8 Å. Porous ACC was evaluated as a potential drug carrier of poorly soluble substances in vitro. Itraconazole and celecoxib remained stable in their amorphous forms within the pores of the material. Drug release rates were significantly enhanced for both drugs (up to 65 times the dissolution rates for the crystalline forms), and supersaturation release of celecoxib was also demonstrated. Citric acid was used to enhance the stability of the ACC nanoparticles within the aggregates, which increased the surface area of the material to over 600 m2 g-1. This porous ACC has potential for use in various applications where surface area is important, including adsorption, catalysis, medication, and bone regeneration.

  • 46.
    Tan, Ha Minh
    et al.
    Hanoi University of Science and Technology.
    Chu Manh, Hung
    Nguyen, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Nguyen Duc, Hoa
    Hanoi University of Science and Technology.
    Duy, Nguyen Van
    Hanoi University of Science and Technology.
    Hieu, Nguyen Van
    Hanoi University of Science and Technology.
    Novel Self-Heated Gas Sensors Using on-Chip Networked Nanowireswith Ultralow Power Consumption2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, ISSN 1944-8244, Vol. 9, p. 6153-6162Article in journal (Refereed)
    Abstract [en]

    The length of single crystalline nanowires (NWs) offers aperfect pathway for electron transfer, while the small diameter of the NWshampers thermal losses to tje environment, substrate, and metal electrodes.Therefore, Joule self-heating effect is nearly ideal for operating NW gassensors at ultralow power consumption, without additional heaters. Therealization of the self-heated NW sensors using the “pick and place”approach is complex, hardly reproducible, low yield, and not applicable formass production. Here, we present the sensing capability of the self-heatednetworked SnO2 NWs effectively prepared by on-chip growth. Ourdeveloped self-heated sensors exhibit a good response of 25.6 to 2.5 ppmNO2 gas, while the response to 500 ppm H2, 100 ppm NH3, 100 ppm H2S,and 500 ppm C2H5OH is very low, indicating the good selectivity of thesensors to NO2 gas. Furthermore, the detection limit is very low, down to 82parts-per-trillion. As-obtained sensing performance under self-heating modeis nearly identical to that under external heating mode. While the power consumption under self-heating mode is extremely low,around hundreds of microwatts, as scaled-down the size of the electrode is below 10 μm. The selectivity of the sensors can becontrolled simply by tuning the loading power that enables simple detection of NO2 in mixed gases. Remarkable performancetogether with a significantly facile fabrication process of the present sensors enhances the potential application of NW sensors innext generation technologies such as electronic noses, the Internet of Things, and smartphone sensing.

  • 47.
    Teramura, Yuji
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology. Univ Tokyo, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Asif, Sana
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Ekdahl, Kristina Nilsson
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology. Linnaeus Univ, Linnaeus Ctr Biomat Chem, SE-39182 Kalmar, Sweden..
    Gustafson, Elisabet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health.
    Nilsson, Bo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Cell Adhesion Induced Using Surface Modification with Cell-Penetrating Peptide-Conjugated Poly(ethylene glycol)-Lipid: A New Cell Glue for 3D Cell-Based Structures2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 1, p. 244-254Article in journal (Refereed)
    Abstract [en]

    We synthesized a novel material, cell-penetrating peptide conjugated poly(ethylene glycol)-lipid (CPP-PEG-lipid), that can induce the adhesion of floating cells. Firm cell adhesion with spreading could be induced by cell surface modification with the CPP-PEG-lipids. Cell adhesion was induced by CPPs but not by any other cationic short peptides we tested. Here, we demonstrated adherence using the floating cell line CCRF-CEM as well as primary human T cells, B cells, erythrocytes, and hepatocytes. As compared to cells grown in suspension, adherent cells were more rapidly induced to attach to substrates with the cell-surface modification. The critical factor for attachment was localization of CPPs at the cell membrane by PEG-lipids with PEG > 20 kDa. These cationic CPPs on PEG chains were able to interact with substrate surfaces such as polystyrene (PS) surfaces, glass surfaces, and PS microfibers that are negatively charged, inducing firm cell adhesion and cell spreading. Also, as opposed to normal cationic peptides that interact strongly with cell membranes, CPPs were less interactive with the cell surfaces because of their cell-penetrating property, making them more available for adhering cells to the substrate surface. No effects on cell viability or cell proliferation were observed after the induction of cell adhesion. With this technique, cells could be easily immobilized onto PS microfibers, an important step in fabricating 3D cell-based structures. Cells immobilized onto 3D PS microfibers were alive, and human hepatocytes showed normal production of urea and albumin on the microfibers. This method is novel in inducing firm cell adhesion-via a one-step treatment.

  • 48.
    Theis-Bröhl, Katharina
    et al.
    Univ Appl Sci, Karlstadt 8, D-27568 Bremerhaven, Germany..
    Vreeland, Erika C.
    Sandia Natl Labs, POB 5800, Albuquerque, NM 87185 USA.;Imag Biosyst LLC, Albuquerque, NM 87106 USA..
    Gomez, Andrew
    Sandia Natl Labs, POB 5800, Albuquerque, NM 87185 USA..
    Huber, Dale L.
    Sandia Natl Labs, POB 5800, Albuquerque, NM 87185 USA..
    Saini, Apurve
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Wolff, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Maranville, Brian B.
    NIST, Ctr Neutron Res, 100 Bur Dr, Gaithersburg, MD 20899 USA..
    Brok, Erik
    NIST, Ctr Neutron Res, 100 Bur Dr, Gaithersburg, MD 20899 USA.;Univ Maryland, Dept Mat Sci & Engn, College Pk, MD 20742 USA.;Univ Copenhagen, Niels Bohr Inst, Nanosci Ctr, DK-21000 Copenhagen O, Denmark..
    Krycka, Kathryn L.
    NIST, Ctr Neutron Res, 100 Bur Dr, Gaithersburg, MD 20899 USA..
    Dura, Joseph A.
    NIST, Ctr Neutron Res, 100 Bur Dr, Gaithersburg, MD 20899 USA..
    Borchers, Julie A.
    NIST, Ctr Neutron Res, 100 Bur Dr, Gaithersburg, MD 20899 USA..
    Self-Assembled Layering of Magnetic Nanoparticles in a Ferrofluid on Silicon Surfaces2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 5, p. 5050-5060Article in journal (Refereed)
    Abstract [en]

    This article describes the three-dimensional self assembly of monodisperse colloidal magnetite nanoparticles (NPs) from a dilute water-based ferrofluid onto a silicon surface and the dependence of the resultant magnetic structure on the applied field. The NPs assemble into close-packed layers on the surface followed by more loosely packed ones. The magnetic field-dependent magnetization of the individual NP layers depends on both the rotational freedom of the layer and the magnetization of the adjacent layers. For layers in which the NPs are more free to rotate, the easy axis of the NP can readily orient along the field direction. In more dense packing, free rotation of the NPs is hampered, and the NP ensembles likely build up quasi-domain states to minimize energy, which leads to lower magnetization in those layers. Detailed analysis of polarized neutron reflectometry data together with model calculations of the arrangement of the NPs within the layers and input from small-angle scattering measurements provide full characterization of the core/shell NP dimensions, degree of chaining, arrangement of the NPs within the different layers, and magnetization depth profile.

  • 49.
    Tian, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ma, Jing
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Donolato, Marco
    BluSense Diagnostics, Copenhagen, Denmark.
    Fougt Hansen, Mikkel
    Technical University of Denmark.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Strömberg, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    On-Particle Rolling Circle Amplification-Based Core-Satellite Magnetic Superstructures for MicroRNA Detection2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 3, p. 2957-2964Article in journal (Refereed)
    Abstract [en]

    Benefiting from the specially tailored properties of the building blocks as well as of the scaffolds, DNA-assembled core satellite superstructures have gained increasing interest-in drug delivery, imaging, and biosensing. The load of satellites plays,,a vital role in core satellite superstructures, and it determines the signal intensity in response to a biological/physical stimulation/actuation. Herein, for the first time, we utilize on-particle rolling circle amplification (RCA) to prepare rapidly responsive-core satellite magnetic superstructures With a high load of magnetic nanoparticle (MNP) Satellites. Combined with duplex-specific nuclease-assisted target recycling) the proposed magnetic superstructures hold great promise in sensitive and rapid microRNA detection. The long single-stranded DNA produced by RCA serving as the scaffold of the core satellite superstructure can be hydrolyzed by duplex-Specific nuclease in the presence of target microRNA, resulting in a release of MNPs that can be quantified in an optomagnetic sensor. The proposed biosensor has a-simple mix separate measure strategy. For let-7b detection, the proposed biosensor offers a wide linear detection range of approximately 5 orders of magnitude with a detection sensitivity of 1 fM. Moreover, it has the capability to discriminate single-nucleotide mismatches and to detect let-7b in cell extracts and serum, thus showing considerable potential for clinical applications.

  • 50.
    Topalian, Zareh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    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.
    Spectroscopic study of the photofixation of SO2 on anatase TiO2 thin films and their oleophobic properties2012In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 4, no 2, p. 672-679Article in journal (Refereed)
    Abstract [en]

    Photoinduced SO2 fixation on anatase TiO2 films was studied by in situ Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The TiO2 films were prepared by reactive DC magnetron sputtering and were subsequently exposed to 50 ppm SO2 gas mixed in synthetic air and irradiated with UV light at substrate temperatures between 298 and 673 K. Simultaneous UV irradiation and SO2 exposure between 373 and 523 K resulted in significant sulfur (S) deposits on crystalline TiO2 films as determined by XPS, whereas amorphous films contained negligible amounts of S. At substrate temperatures above 523 K, the S deposits readily desorbed from TiO2. The oxidation state of sulfur successively changed from S4+ for SO2 adsorbed on crystalline TiO2 films at room temperature without irradiation to S6+ for films exposed to SO2 at elevated temperatures with simultaneous irradiation. In situ FTIR was used to monitor the temporal evolution of the photoinduced surface reaction products formed on the TiO2 surfaces. It is shown that band gap excitation of TiO2 results in photoinduced oxidation of SO2, which at elevated temperatures become coordinated to the TiO2 lattice through interactions with O vacancies and form sulfite and sulfate surface species. These species makes the surface acidic, which is manifested in nondetectable adherence of stearic acid to the modified surface. The modified films show good chemical stability as evidenced by sonication and repeated recycling of the films. The results suggest a new method to functionalize wide band gap oxide surfaces by means of photoinduced reactions in reactive gases at elevated substrate temperatures. In the case of anatase TiO2 in reactive SO2 gas, we here show that such functionalization yields surfaces with excellent oleophobic properties, as probed by adhesion of stearic acid.

12 1 - 50 of 68
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