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  • 201. Order onlineBuy this publication >>
    Mickan, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Deposition of Al-doped ZnO films by high power impulse magnetron sputtering2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Transparent conducting oxides (TCOs) are an important class of materials with many applications such as low emissivity coatings, or transparent electrodes for photovoltaics and flat panel displays. Among the possible TCO materials, Al-doped ZnO (AZO) is studied due to its relatively low cost and abundance of the raw materials. Thin films of AZO are commonly produced using physical vapour deposition techniques such as magnetron sputtering. However, there is a problem with the homogeneity of the films using reactive direct current magnetron sputtering (DCMS). This homogeneity problem can be related to the bombardment of the growing film with negative oxygen ions, that can cause additional acceptor defects and the formation of insulating secondary phases. In this work AZO films are deposited by high power impulse magnetron sputtering (HiPIMS), a technique in which high instantaneous current densities are achieved by short pulses of low duty cycle.

    In the first part of this thesis, the possibility to improve the homogeneity of the deposited AZO films by using HiPIMS is demonstrated. This improvement can be related to the high instantaneous sputtering rate during the HiPIMS pulses, so the process can take place in the metal mode. This allows for a lower oxygen ion bombardment of the growing film, which can help to avoid the formation of secondary phases. Another problem of AZO is the stability of the properties in humid environments. To assess this problem, the degradation of the electrical properties after an aging procedure was investigated for films deposited by both DCMS and by HiPIMS. A method was proposed, to restore the properties of the films, using a low temperature annealing under N2 atmosphere. The improvement of the electrical properties of the films could be related to a diffusion process, where water is diffusing out of the films. Then, the influence of the substrate temperature on the properties of AZO films deposited by HiPIMS was studied. The electrical, optical and structural properties were found to improve with increasing substrate temperature up to 600 C. This improvement can be mostly explained by the increase in crystalline quality and the annealing of defects. Finally, the deposition of AZO films on flexible PET substrates was investigated. The films are growing as a thick porous layer of preferentially c-axis oriented columns on top of a thin dense seed layer. The evolution of the sheet resistance of the films after bending the films with different radii was studied. There is an increase in the sheet resistance of the films with decreasing bending radius, that is less pronounced for thicker films.

    List of papers
    1. Room temperature deposition of homogeneous, highly transparent and conductive Al-doped ZnO films by reactive high power impulse magnetron sputtering
    Open this publication in new window or tab >>Room temperature deposition of homogeneous, highly transparent and conductive Al-doped ZnO films by reactive high power impulse magnetron sputtering
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    2016 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 157, p. 742-749Article in journal (Refereed) Published
    Abstract [en]

    Aluminum doped zinc oxide (AZO) films have been deposited using reactive high power impulse magnetron sputtering (HiPIMS) and reactive direct current (DC) magnetron sputtering from an alloyed target without thermal assistance. These films have been compared in terms of their optical, electrical and structural properties. While both DC and HiPIMS deposited films show comparable transmittance, their electrical properties are significantly improved by the HiPIMS process. The HiPIMS deposited films show a low resistivity down to the order of 10(-4) Omega cm with a good homogeneity across the substrate, making them potential candidates for electrodes in solar cells. The density of electrons reached up to 11 x 10(20) cm(-3), making ionized impurities the main scattering defects. This improvement of the film properties can be related to the specific plasma/target interactions in a HiPIMS discharge. This allows the process to take place in the transition mode and to deposit highly conductive, transparent AZO films on large surfaces at low temperature. While the overall oxygen content is above that of stoichiometric ZnO, higher localization of oxygen is found at the interfaces between crystalline domains with substoichiometric composition. (C) 2016 Elsevier B.V. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER SCIENCE BV, 2016
    Keywords
    Transparent conducting oxide; AZO; Thin films; Electronic properties; HiPIMS
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-132201 (URN)10.1016/j.solmat.2016.07.020 (DOI)000384391700088 ()
    Note

    Funding Agencies|European Commission within the DocMASE project

    Available from: 2016-11-01 Created: 2016-10-21 Last updated: 2017-11-29
    2. Restoring the Properties of Transparent Al-Doped ZnO Thin Film Electrodes Exposed to Ambient Air
    Open this publication in new window or tab >>Restoring the Properties of Transparent Al-Doped ZnO Thin Film Electrodes Exposed to Ambient Air
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    2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 27, p. 14426-14433Article in journal (Refereed) Published
    Abstract [en]

    The properties of Al-doped ZnO (AZO) films are known to degrade with exposure to humidity. Different AZO films deposited using reactive direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HiPIMS) have been aged in ambient laboratory conditions and annealed at temperatures between 160 and 180 degrees C in a N-2 atmosphere. Their electrical and optical properties, which have been investigated both ex situ and in situ during the annealing, are improved. The results of the in situ measurements are interpreted in terms of a diffusion process, where hydroxyl groups are decomposed and water is diffusing out of the films. As hydroxyl groups are known to act as a trap for charge carriers in ZnO, their removal from the film can explain the improvement of the electrical properties by the annealing.

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2017
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-139560 (URN)10.1021/acs.jpcc.7b03020 (DOI)000405761600006 ()
    Note

    Funding Agencies|European Commission

    Available from: 2017-08-08 Created: 2017-08-08 Last updated: 2017-11-10
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    Deposition of Al-doped ZnO films by high power impulse magnetron sputtering
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  • 202.
    Mickan, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. University of Lorraine, France.
    Stoffel, Mathieu
    University of Lorraine, France.
    Rinnert, Herve
    University of Lorraine, France.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Horwat, David
    University of Lorraine, France.
    Restoring the Properties of Transparent Al-Doped ZnO Thin Film Electrodes Exposed to Ambient Air2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 27, p. 14426-14433Article in journal (Refereed)
    Abstract [en]

    The properties of Al-doped ZnO (AZO) films are known to degrade with exposure to humidity. Different AZO films deposited using reactive direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HiPIMS) have been aged in ambient laboratory conditions and annealed at temperatures between 160 and 180 degrees C in a N-2 atmosphere. Their electrical and optical properties, which have been investigated both ex situ and in situ during the annealing, are improved. The results of the in situ measurements are interpreted in terms of a diffusion process, where hydroxyl groups are decomposed and water is diffusing out of the films. As hydroxyl groups are known to act as a trap for charge carriers in ZnO, their removal from the film can explain the improvement of the electrical properties by the annealing.

  • 203.
    Miglbauer, Eva
    et al.
    Johannes Kepler University of Linz, Austria.
    Demitri, Nicola
    Elettra Sincrotrone Trieste, Italy.
    Himmelsbach, Markus
    Johannes Kepler University of Linz, Austria.
    Monkowius, Uwe
    Johannes Kepler University of Linz, Austria.
    Sariciftci, Niyazi S.
    Johannes Kepler University of Linz, Austria.
    Glowacki, Eric
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Johannes Kepler University of Linz, Austria.
    Oppelt, Kerstin T.
    Johannes Kepler University of Linz, Austria; University of Zurich, Switzerland.
    Synthesis and Investigation of N,N-benzylated Epindolidione Derivatives as Organic Semiconductors2016In: CHEMISTRYSELECT, ISSN 2365-6549, Vol. 1, no 20, p. 6349-6355Article in journal (Refereed)
    Abstract [en]

    We report how the N, N-disubstitution of epindolidione with a benzyl group surprisingly leads to irreversibility of oxidation and thus to only n-type transport in a material with otherwise quasi-reversible reduction and oxidation and charge transport ambipolarity. Cyclic voltammetry, bulk electrolysis and UV-Vis spectroscopic methods were applied to elucidate the electrochemical reaction pathway leading to oxidative degradation and conclude that the same product that can be produced electrochemically is also found in the solid-state device. The chemical substitution of hydrogen-bonded acridone-based semiconductors can lead to substantial changes in their electrical properties, and more broadly, the electrochemistry of organic semiconductors in solution can be closely related to their solid-state charge transport phenomena.

  • 204.
    Mitraka, Evangelia
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gryszel, Maciej
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Singh, Amritpal
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Warczak, Magdalena
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Mitrakas, Manassis
    Aristotle University of Thessaloniki, Thessaloniki, Greece.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Glowacki, Eric
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Electrocatalytic Production of Hydrogen Peroxide with Poly(3,4-ethylenedioxythiophene) Electrodes2019In: Advanced Sustainable Systems, ISSN 2366-7486, Vol. 3, no 2, p. 1-6, article id 1800110Article in journal (Refereed)
    Abstract [en]

    Electrocatalysis for energy‐efficient chemical transformations is a central concept behind sustainable technologies. Numerous efforts focus on synthesizing hydrogen peroxide, a major industrial chemical and potential fuel, using simple and green methods. Electrochemical synthesis of peroxide is a promising route. Herein it is demonstrated that the conducting polymer poly(3,4‐ethylenedioxythiophene), PEDOT, is an efficient and selective heterogeneous catalyst for the direct reduction of oxygen to hydrogen peroxide. While many metallic catalysts are known to generate peroxide, they subsequently catalyze decomposition of peroxide to water. PEDOT electrodes can support continuous generation of high concentrations of peroxide with Faraday efficiency remaining close to 100%. The mechanisms of PEDOT‐catalyzed reduction of O2 to H2O2 using in situ spectroscopic techniques and theoretical calculations, which both corroborate the existence of a chemisorbed reactive intermediate on the polymer chains that kinetically favors the selective reduction reaction to H2O2, are explored. These results offer a viable method for peroxide electrosynthesis and open new possibilities for intrinsic catalytic properties of conducting polymers.

  • 205.
    Mitraka, Evangelia
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Jonsson, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Oxygen-induced doping on reduced PEDOT2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 9, p. 4404-4412Article in journal (Refereed)
    Abstract [en]

    The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) has shown promise as air electrode in renewable energy technologies like metal-air batteries and fuel cells. PEDOT is based on atomic elements of high abundance and is synthesized at low temperature from solution. The mechanism of oxygen reduction reaction (ORR) over chemically polymerized PEDOT: Cl still remains controversial with eventual role of transition metal impurities. However, regardless of the mechanistic route, we here demonstrate yet another key active role of PEDOT in the ORR mechanism. Our study demonstrates the decoupling of conductivity (intrinsic property) from electrocatalysis (as an extrinsic phenomenon) yielding the evidence of doping of the polymer by oxygen during ORR. Hence, the PEDOT electrode is electrochemically reduced (undoped) in the voltage range of ORR regime, but O-2 keeps it conducting; ensuring PEDOT to act as an electrode for the ORR. The interaction of oxygen with the polymer electrode is investigated with a battery of spectroscopic techniques.

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  • 206.
    Modarresi, Mohsen
    et al.
    Ferdawsi Univ Mashhad, Iran.
    Franco Gonzalez, Felipe
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Autonomous Univ Madrid, Spain.
    Zozoulenko, Igor
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Computational microscopy study of the granular structure and pH dependence of PEDOT:PSS2019In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, no 12, p. 6699-6711Article in journal (Refereed)
    Abstract [en]

    Computational microscopy based on Martini coarse grained molecular dynamics (MD) simulations of a doped conducting polymer poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (best known as PEDOT:PSS) was performed focussing on the formation of the granular structure and PEDOT crystallites, and the effect of pH on the material morphology. The PEDOT:PSS morphology is shown to be sensitive to the initial distribution of PEDOT and PSS in the solution, and the results of the modelling suggest that the experimentally observed granular structure of PEDOT:PSS can be only obtained if the PEDOT/PSS solution is in the dispersive state in the initial crystallization stages. Variation of the pH is demonstrated to strongly affect the morphology of PEDOT:PSS films, altering their structure between granular-type and homogeneous. It also affects the size of crystallites and the relative arrangement of PEDOT and PSS chains. It is shown that the crystallites in PEDOT:PSS are smaller than those in PEDOT with molecular counterions such as PEDOT:tosylate, which is consistent with the available experimental data. The predicted changes of the PEDOT:PSS morphology with variation of the pH can be tested experimentally, and the calculated atomistic picture of PEDOT:PSS films (not accessible by conventional experimental techniques) is instrumental for understanding the material structure and building realistic models of PEDOT:PSS morphology.

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  • 207.
    Modarresi, Mohsen
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Ferdowsi Univ Mashhad, Iran.
    Franco Gonzalez, Felipe
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Morphology and ion diffusion in PEDOT:Tos. A coarse grained molecular dynamics simulation2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 25, p. 17188-17198Article in journal (Refereed)
    Abstract [en]

    A Martini coarse-grained Molecular Dynamics (MD) model for the doped conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is developed. The morphology of PEDOT:Tos (i.e. PEDOT doped with molecular tosylate) and its crystallization in aqueous solution for different oxidation levels were calculated using the developed method and compared with corresponding all atomistic MD simulations. The diffusion coefficients of Na+ and Cl- ions in PEDOT:Tos are studied using the developed coarse-grained MD approach. It is shown that the diffusion coefficients decrease exponentially as the hydration level is reduced. It is also predicted that the diffusion coefficients decrease when the doping level of PEDOT is increased. The observed behavior is related to the evolution of water clusters and trapping of ions around the polymer matrix as the hydration level changes. The predicted behavior of the ionic diffusion coefficients can be tested experimentally, and we believe that molecular picture of ionic diffusion in PEDOT unraveled in the present study is instrumental for the design of polymeric materials and devices for better and enhanced performance.

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  • 208.
    Morchutt, Claudius
    et al.
    Max Planck Institute Solid State Research, Germany; Ecole Polytech Federal Lausanne, Switzerland.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Strasser, Carola
    Max Planck Institute Solid State Research, Germany.
    Starke, Ulrich
    Max Planck Institute Solid State Research, Germany.
    Gutzler, Rico
    Max Planck Institute Solid State Research, Germany.
    Kern, Klaus
    Max Planck Institute Solid State Research, Germany; Ecole Polytech Federal Lausanne, Switzerland.
    Interplay of Chemical and Electronic Structure on the Single-Molecule Level in 2D Polymerization2016In: ACS NANO, ISSN 1936-0851, Vol. 10, no 12, p. 11511-11518Article in journal (Refereed)
    Abstract [en]

    Single layers of covalently linked organic materials in the form of two-dimensional (2D) polymers constitute structures complementary to inorganic 2D materials. The electronic properties of 2D polymers may be manipulated through a deliberate choice of the organic precursors. Here we address the changes in electronic CO structure-from precursor molecule to oligomer by scanning tunneling spectroscopy and ultraviolet photoelectron spectroscopy. For this purpose, we introduce the polymerization reaction of 1,3,5-tris(4-carboxyphenyl)benzene via decarboxylation on Cu(111), which is thoroughly characterized by scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. We present a comprehensive study of a contamination-free on-surface coupling scheme and study how dehydrogenation, decarboxylation, and polymerization affect the electronic structure on the molecular level.

  • 209.
    Mugheri, Abdul Qayoom
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn and Technol, Pakistan.
    Abro, Muhammad Ishaq
    Mehran Univ Engn and Technol, Pakistan.
    Chaudhry, Saleem Raza
    Univ Engn and Technol, Pakistan.
    Amaral, Luis
    Univ Engn and Technol, Pakistan; Univ Lisbon, Portugal.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Facile efficient earth abundant NiO/C composite electrocatalyst for the oxygen evolution reaction Electronic supplementary information (ESI) available. See DOI: 10.1039/c8ra10472g2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 10, p. 5701-5710Article in journal (Refereed)
    Abstract [en]

    Due to the increasing energy consumption, designing efficient electrocatalysts for electrochemical water splitting is highly demanded. In this study, we provide a facile approach for the design and fabrication of efficient and stable electrocatalysts through wet chemical methods. The carbon material, obtained by the dehydration of sucrose sugar, provides high surface area for the deposition of NiO nanostructures and the resulting NiO/C catalysts show higher activity towards the OER in alkaline media. During the OER, a composite of NiO with 200 mg C can produce current densities of 10 and 20 mA cm(-2) at a bias of 1.45 V and 1.47 V vs. RHE, respectively. Electrochemical impedance spectroscopy experiments showed the lowest charge transfer resistance and the highest double layer capacitance in the case of the NiO/C composite with 200 mg C. The presence of C for the deposition of NiO nanostructures increases the active centers and consequently a robust electrocatalytic activity is achieved. The obtained results in terms of the low overpotential and small Tafel slope of 55 mV dec(-1) for non-precious catalysts are clear indications for the significant advancement in the field of electrocatalyst design for water splitting. This composite material based on NiO/C is simple and scalable for widespread use in various applications, especially in supercapacitors and lithium-ion batteries.

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  • 210.
    Mugheri, Abdul Qayoom
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn and Technol, Pakistan.
    Abro, Muhammad Ishaq
    Mehran Univ Engn and Technol, Pakistan.
    Mallah, Arfana Begum
    Univ Sindh Jamshoro, Pakistan.
    Memon, Gulam Zuhra
    Univ Sindh Jamshoro, Pakistan.
    Khan, Humaira
    Univ Sindh Jamshoro, Pakistan.
    Abbasi, Mazhar Ali
    Univ Sindh, Pakistan.
    Halepoto, Imran Ali
    Univ Sindh, Pakistan.
    Chaudhry, Saleem Raza
    Univ Engn and Technol, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    An advanced and efficient Co3O4/C nanocomposite for the oxygen evolution reaction in alkaline media2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, RSC ADVANCES, Vol. 9, no 59, p. 34136-34143Article in journal (Refereed)
    Abstract [en]

    The design of efficient nonprecious catalysts for the hydrogen evolution reaction (HER) or the oxygen evolution reaction (OER) is a necessary, but very challenging task to uplift the water-based economy. In this study, we developed a facile approach to produce porous carbon from the dehydration of sucrose and use it for the preparation of nanocomposites with cobalt oxide (Co3O4). The nanocomposites were studied by the powder X-ray diffraction and scanning electron microscopy techniques, and they exhibited the cubic phase of cobalt oxide and porous structure of carbon. The nanocomposites showed significant OER activity in alkaline media, and the current densities of 10 and 20 mA cm(-2) could be obtained at 1.49 and 1.51 V versus reversible hydrogen electrode (RHE), respectively. The impedance study confirms favorable OER activity on the surface of the prepared nanocomposites. The nanocomposite is cost-effective and can be capitalized in various energy storage technologies.

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  • 211.
    Mugheri, Abdul Qayoom
    et al.
    Univ Sindh, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn and Technol, Pakistan.
    Bhatti, Adeel Liaquat
    Univ Sindh, Pakistan.
    Memon, Nusrat Naeem
    Univ Sindh, Pakistan.
    Memon, Jamil-ur-Rehman
    Univ Sindh, Pakistan.
    Abro, Muhammad Ishaque
    Mehran Univ Engn and Technol, Pakistan.
    Shah, Aqeel Ahmed
    NED Univ Engn Sci and Technol, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Hullio, Ahmed Ali
    Univ Sindh, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Efficient tri-metallic oxides NiCo2O4/CuO for the oxygen evolution reaction2019In: RSC ADVANCES, Vol. 9, no 72, p. 42387-42394Article in journal (Refereed)
    Abstract [en]

    In this study, a simple approach was used to produce nonprecious, earth abundant, stable and environmentally friendly NiCo2O4/CuO composites for the oxygen evolution reaction (OER) in alkaline media. The nanocomposites were prepared by a low temperature aqueous chemical growth method. The morphology of the nanostructures was changed from nanowires to porous structures with the addition of CuO. The NiCo2O4/CuO composite was loaded onto a glassy carbon electrode by the drop casting method. The addition of CuO into NiCo2O4 led to reduction in the onset potential of the OER. Among the composites, 0.5 grams of CuO anchored with NiCo2O4 (sample 2) demonstrated a low onset potential of 1.46 V vs. a reversible hydrogen electrode (RHE). A current density of 10 mA cm(-2) was achieved at an over-potential of 230 mV and sample 2 was found to be durable for 35 hours in alkaline media. Electrochemical impedance spectroscopy (EIS) indicated a small charge transfer resistance of 77.46 ohms for sample 2, which further strengthened the OER polarization curves and indicates the favorable OER kinetics. All of the obtained results could encourage the application of sample 2 in water splitting batteries and other energy related applications.

  • 212.
    Musumeci, Chiara
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Northwestern University, IL 60208 USA.
    Borgani, Riccardo
    KTH Royal Institute Technology, Sweden.
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Haviland, David
    KTH Royal Institute Technology, Sweden.
    Multiparameter investigation of bulk heterojunction organic photovoltaics2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 73, p. 46313-46320Article in journal (Refereed)
    Abstract [en]

    A key parameter to improve the performance of organic solar cells is the optimization of electronic phenomena at donor-acceptor interfaces through the optimization of the morphology of the bulk heterojunction. The correlative mapping of morphological, electrical and mechanical properties at the nanoscale by advanced scanning probe microscopy techniques allows for a detailed characterization of the local structure-property relationships in bulk heterojunctions solar cells. Unique opportunities for the investigation of these photoactive films are shown here, ultimately suggesting fundamental guidelines toward the accurate engineering of these materials at the nanoscale.

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  • 213.
    Musumeci, Chiara
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zeglio, Erica
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ouyang, Liangqi
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gabrielsson, Roger
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Organic electrochemical transistors from supramolecular complexes of conjugated polyelectrolyte PEDOTS2019In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 10, p. 2987-2993Article in journal (Refereed)
    Abstract [en]

    Counterion exchange strategies are used to modify the hydrophilic character of the self-doped conjugated polyelectrolyte PEDOTS. The supramolecular complexes, soluble in organic solvents, are suitable to fabricate finely performing thin active layers in organic electrochemical transistors (OECTs). We demonstrate that ionic transport in these PEDOTS based complexes, thus their performance in OECT devices, is governed by a delicate balance among degree of doping, wettability and porosity, which can be controlled by a precise tuning of the polyelectrolyte/hydrophobic counterion ratio. We also show that the device operation can be modulated by varying the composition of the aqueous electrolyte in a range compatible with biological processes, making these materials suitable candidates to be interfaced with living cells.

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  • 214.
    Mühlbacher, Marlene
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sartory, Bernhard
    Mat Ctr Leoben Forsch GmbH, Austria.
    Schalk, Nina
    Univ Leoben, Austria.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petrov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Univ Illinois, IL 61801 USA; Univ Illinois, IL 61801 USA.
    Greene, Joseph E
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Univ Illinois, IL 61801 USA; Univ Illinois, IL 61801 USA.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Mitterer, Christian
    Univ Leoben, Austria.
    Enhanced Ti0.84Ta0.16N diffusion barriers, grown by a hybrid sputtering technique with no substrate heating, between Si(001) wafers and Cu overlayers2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 5360Article in journal (Refereed)
    Abstract [en]

    We compare the performance of conventional DC magnetron sputter-deposited (DCMS) TiN diffusion barriers between Cu overlayers and Si(001) substrates with Ti0.84Ta0.16N barriers grown by hybrid DCMS/high-power impulse magnetron sputtering (HiPIMS) with substrate bias synchronized to the metal-rich portion of each pulse. DCMS power is applied to a Ti target, and HiPIMS applied to Ta. No external substrate heating is used in either the DCMS or hybrid DCMS/HiPIMS process in order to meet future industrial thermal-budget requirements. Barrier efficiency in inhibiting Cu diffusion into Si(001) while annealing for 1 hour at temperatures between 700 and 900 degrees C is investigated using scanning electron microscopy, X-ray diffraction, four-point-probe sheet resistance measurements, transmission electron microscopy, and energy-dispersive X-ray spectroscopy profiling. Ti0.84Ta0.16N barriers are shown to prevent large-scale Cu diffusion at temperatures up to 900 degrees C, while conventional TiN barriers fail at amp;lt;= 700 degrees C. The improved performance of the Ti0.84Ta0.16N barrier is due to film densification resulting from HiPIMS pulsed irradiation of the growing film with synchronized Ta ions. The heavy ion bombardment dynamically enhances near-surface atomic mixing during barrier-layer deposition.

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  • 215.
    Nguyen, Quang Khuyen
    et al.
    Ton Duc Thang Univ, Vietnam.
    Martinez Gil, Jose Gabriel
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Univ Politecn Cartagena Aulario II, Spain.
    Kaasik, Friedrich
    Univ Tartu, Estonia.
    Tamm, Tarmo
    Univ Tartu, Estonia.
    Otero, Toribio F.
    Univ Politecn Cartagena Aulario II, Spain.
    Kiefer, Rudolf
    Ton Duc Thang Univ, Vietnam.
    Solvent effects on carbide-derived-carbon trilayer bending actuators2019In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 247, p. 170-176Article in journal (Refereed)
    Abstract [en]

    Bending actuators were prepared by depositing carbide-derived carbon, a material typical for electric double layer capacitors, on both sides of poly-vinylidenefluoride membranes, forming CDC-trilayers. Their actuation properties were studied using 0.5 M solutions of lithium perchlorate (LiClO4) in different solvents: water, ethylene glycol, acetonitrile, and propylene carbonate. The goal of this work was to study the actuation mechanism, charging-discharging properties in these solvents, as well as to establish the optimal solvent for maximum bending displacement. It was found that while the actuation direction was the same for all solvents, pointing to similar mechanism, the exchanged charge and the displacement differed considerably. Moreover, the highest specific capacitance found in ethylene glycol did not bring along the highest displacement, neither was the highest exchanged charge of propylene carbonate the most efficient option, the acetonitrile was the clear winner. The available electrochemical windows for the reversible charging also differed considerably.

  • 216.
    Ning, Weihua
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Tech Univ, Peoples R China.
    Wang, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wu, Bo
    Nanyang Technol Univ, Singapore.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Yan, Zhibo
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Univ, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Tao, Youtian
    Nanjing Tech Univ, Peoples R China.
    Liu, Jun-Ming
    Nanjing Univ, Peoples R China.
    Huang, Wei
    Nanjing Tech Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sum, Tze Chien
    Nanyang Technol Univ, Singapore.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Long Electron-Hole Diffusion Length in High-Quality Lead-Free Double Perovskite Films2018In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 30, no 20, article id 1706246Article in journal (Refereed)
    Abstract [en]

    Developing environmentally friendly perovskites has become important in solving the toxicity issue of lead-based perovskite solar cells. Here, the first double perovskite (Cs2AgBiBr6) solar cells using the planar structure are demonstrated. The prepared Cs2AgBiBr6 films are composed of high-crystal-quality grains with diameters equal to the film thickness, thus minimizing the grain boundary length and the carrier recombination. These high-quality double perovskite films show long electron-hole diffusion lengths greater than 100 nm, enabling the fabrication of planar structure double perovskite solar cells. The resulting solar cells based on planar TiO2 exhibit an average power conversion efficiency over 1%. This work represents an important step forward toward the realization of environmentally friendly solar cells and also has important implications for the applications of double perovskites in other optoelectronic devices.

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  • 217.
    Nunez, Julius Andrew P.
    et al.
    Univ Philippines Manila, Philippines; Univ Philippines Diliman, Philippines.
    Salapare, Hernando S. III
    Univ Philippines Manila, Philippines; Univ Philippines Open Univ, Philippines; Pamantasan Ng Lungsod Ng Maynila, Philippines.
    Villamayor, Michelle M
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    De Los Santos Valladares, Luis
    Univ Cambridge, England; Univ Nacl Mayor San Marcos, Peru.
    Ramos, Henry J.
    Univ Philippines Diliman, Philippines.
    Photodegradation of Rhodamine 6G by Amorphous TiO2 Films Grown on Polymethylmethacrylate by Magnetron Sputtering2017In: PROTECTION OF METALS AND PHYSICAL CHEMISTRY OF SURFACES, ISSN 2070-2051, Vol. 53, no 6, p. 1022-1027Article in journal (Refereed)
    Abstract [en]

    Titanium dioxide (TiO2) was deposited on polymethylmethacrylate (PMMA) substrates by magnetron sputtering using a Compact Planar Magnetron sputtering device at different flow rate ratios of O-2/Ar. The deposited TiO2 on PMMA substrates were characterized using X-ray Diffraction analysis, X-ray Photoelectron Spectroscopy, Fourier Transform Infrared Spectroscopy, UV-Visible Spectroscopy, and Scanning Electron Microscopy (SEM). These techniques confirm the deposition of a chemically stable amorphous TiO2 layer on the PMMA surface. Photocatalytic activity of the amorphous TiO2 layers were tested via photodegradation of Rhodamine 6G (Rh6G) dye solution. The samples were able to degrade 18-27% of the Rh6G solution after the initial 25 minutes of UV irradiation and complete degradation of Rh6G was observed after 7 hours of UV irradiation.

  • 218.
    Nygren, K.
    et al.
    Uppsala University, Sweden; Impact Coatings AB, Westmansgatan 29, SE-58216 Linkoping, Sweden.
    Samuelsson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Nanoscale engineering. Linköping University, Faculty of Science & Engineering. Impact Coatings AB, Westmansgatan 29, SE-58216 Linkoping, Sweden.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Impact Coatings AB, Westmansgatan 29, SE-58216 Linkoping, Sweden.
    Jansson, U.
    Uppsala University, Sweden.
    Optical methods to quantify amorphous carbon in carbide-based nanocomposite coatings2017In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 638, p. 291-297Article in journal (Refereed)
    Abstract [en]

    We report how the total carbon content and the amorphous carbon (a-C) phase fraction in transition metal carbide/a-C nanocomposite coatings can be obtained using optical methods, which are much more practical for industrial use than conventional X-ray photoelectron spectroscopy. A large set of carbon-containing nanocomposite coatings deposited using different magnetron sputtering techniques were analyzed by X-ray photoelectron spectroscopy, reflectance spectrophotometry, and spectroscopic ellipsometry. The chemical composition and the a-C phase fraction were determined by X-ray photoelectron spectroscopy for each coating and results are presented for the Ti-C, Cr-C, and Nb-C systems. The composition and the a-C phase fraction are correlated to optical reflectance in the visible range, by parametrization in L*a*b* color space, and by ellipsometry primary data. Results show that it is possible to rapidly estimate the composition and the a-C fraction using these optical methods. We propose that optical methods have promising use in the industry as a cost-efficient technique for characterization of carbide-based coatings. (C) 2017 Elsevier B.V. All rights reserved.

  • 219.
    Nygren, Kristian
    et al.
    Uppsala University, Sweden; Impact Coatings AB, Westmansgatan 29, S-58216 Linkoping, Sweden.
    Mikaela Andersson, Anna
    ABB Corp Research, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jansson, Ulf
    Uppsala University, Sweden.
    Passive films on nanocomposite carbide coatings for electrical contact applications2017In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 52, no 13, p. 8231-8246Article in journal (Refereed)
    Abstract [en]

    Nanocomposite transition metal carbide/amorphous carbon coatings (Me-C/a-C) deposited by magnetron sputtering have excellent electrical contact properties. The contact resistance can be as low as that of noble metal coatings, although it is known to vary by several orders of magnitude depending on the deposition conditions. We have investigated a nanocrystalline niobium carbide/amorphous carbon (NbC (x) /a-C:H) model system aiming to clarify factors affecting the contact resistance for this group of contact materials. For the first time, the surface chemistry is systematically studied, by angle-resolved X-ray photoelectron spectroscopy, and in extension how it can explain the contact resistance. The coatings presented a mean oxide thickness of about 1 nm, which could be grown to 8 nm by annealing. Remarkably, the contact resistances covered four orders of magnitude and were found to be exponentially dependent on the mean oxide thickness. Moreover, there is an optimum in the amount of a-C:H phase where the contact resistance drops very significantly and it is thus important to not only consider the mean oxide thickness. To explain the results, a model relying on surface chemistry and contact mechanics is presented. The lowest contact resistance of a nanocomposite matched that of a gold coating at 1 N load (vs. gold), and such performance has previously not been demonstrated for similar nanocomposite materials, highlighting their useful properties for electrical contact applications.

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  • 220.
    Oruganti, Baswanth
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Bioinformatics. Linköping University, Faculty of Science & Engineering.
    Wang, Jun
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Durbeej, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Bioinformatics. Linköping University, Faculty of Science & Engineering.
    Computational Insight to Improve the Thermal Isomerisation Performance of Overcrowded Alkene-Based Molecular Motors through Structural Redesign2016In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 17, no 21, p. 3399-3408Article in journal (Refereed)
    Abstract [en]

    Synthetic overcrowded alkene-based molecular motors achieve 360° unidirectional rotary motion of one motor half (rotator) relative to the other (stator) through sequential photochemical and thermal isomerisation steps. In order to facilitate and expand the use of these motors for various applications, it is important to investigate ways to increase the rates and efficiencies of the reactions governing the rotary motion. Here, we use computational methods to explore whether the thermal isomerisation performance of some of the fastest available motors of this type can be further improved by reducing the sizes of the motor halves. Presenting three new redesigned motors that combine an indanylidene rotator with a cyclohexadiene, pyran or thiopyran stator, we first use multiconfigurational quantum chemical methods to verify that the photoisomerisations of these motors sustain unidirectional rotary motion. Then, by performing density functional calculations, we identify both stepwise and concerted mechanisms for the thermal isomerisations of the motors and show that the rate-determining free-energy barriers of these processes are up to 25 kJ mol−1 smaller than those of the original motors. Furthermore, the thermal isomerisations of the redesigned motors proceed in fewer steps. Altogether, the results suggest that the redesigned motors are useful templates for improving the thermal isomerisation performance of existing overcrowded alkene-based motors.

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  • 221.
    Ouyang, Liangqi
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Musumeci, Chiara
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Imaging the Phase Separation Between PEDOT and Polyelectrolytes During Processing of Highly Conductive PEDOT:PSS Films2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 35, p. 19764-19773Article in journal (Refereed)
    Abstract [en]

    Treating PEDOT:PSS (Clevios) with certain additives, such as ethylene glycol (EG), dimethyl sulfoxide (DMSO) and sorbitol, has been shown to increase the conductivity of this material from roughly 1 to nearly 1000 S/cm. Using a slow drying method, we show that the additive induced a separation between free PSS and reorganized PEDOT:PSS complexes in the highly conductive PEDOT:PSS films. Additives (DMSO, DEG, and PEG 400) were included in PEDOT:PSS aqueous dispersions at large volume fractions. The mixtures were slowly dried under room conditions. During drying, the evaporation of water resulted in an additive-rich solvent mixture from which the reorganized PEDOT:PSS complexes aggregated " into a dense film while free PSS remained in the solution. Upon complete drying, PSS formed a transparent rim film around the conducting PEDOT film. The chemical compositions of the two phases were studied using an infrared microscope. This removal of PSS resulted in more compact packing of PEDOT molecules, as confirmed by X-ray diffraction measurements. X-ray photoelectron spectroscopy and atomic force microscope measurements suggested the enrichment of PEDOT on the film surface after PSS separation. Through a simple drying process in an additive-containing dispersion, the conductivity of PEDOT films increased from 0.1 to 200-400 S/cm. Through this method, we confirmed the existence of two phases in additive-treated and highly conductive PEDOT:PSS films. The proper separation between PSS and PEDOT will be of relevance in designing strategies to process high-performance plastic electrodes.

  • 222.
    Palisaitis, Justinas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Direct observation of spinodal decomposition phenomena in InAlN alloys during in-situ STEM heating2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 44390Article in journal (Refereed)
    Abstract [en]

    The spinodal decomposition and thermal stability of thin In0.72Al0.28N layers and In0.72Al0.28N/AlN superlattices with AlN(0001) templates on Al2O3(0001) substrates was investigated by in-situ heating up to 900 degrees C. The thermally activated structural and chemical evolution was investigated in both plan-view and cross-sectional geometries by scanning transmission electron microscopy in combination with valence electron energy loss spectroscopy. The plan-view observations demonstrate evidence for spinodal decomposition of metastable In0.72Al0.28N after heating at 600 degrees C for 1 h. During heating compositional modulations in the range of 2-3 nm-size domains are formed, which coarsen with applied thermal budgets. Cross-sectional observations reveal that spinodal decomposition begin at interfaces and column boundaries, indicating that the spinodal decomposition has a surface-directed component.

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  • 223.
    Pang, Tiqiang
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Xidian Univ, Peoples R China.
    Sun, Kai
    Xidian Univ, Peoples R China; Ningbo Univ, Peoples R China.
    Wang, Yucheng
    Northwestern Polytech Univ, Peoples R China.
    Luan, Suzhen
    Xian Univ Sci and Technol, Peoples R China.
    Zhang, Yuming
    Xidian Univ, Peoples R China.
    Zhu, Yuejin
    Ningbo Univ, Peoples R China.
    Hu, Ziyang
    Ningbo Univ, Peoples R China.
    Jia, Renxu
    Xidian Univ, Peoples R China.
    Hysteresis effects on carrier transport and photoresponse characteristics in hybrid perovskites2020In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 8, no 6, p. 1962-1971Article in journal (Refereed)
    Abstract [en]

    Organic-inorganic hybrid perovskites have recently emerged as promising potential candidate materials in the area of photoelectrics due to their unparalleled optoelectronic features. However, the performance of an optoelectronic device is always affected by the mixed ionic and electronic conducting behavior within perovskites. Herein, the hysteresis effect on carrier mobility and photoresponse characteristics of perovskites were investigated through adding rational additives to the precursor solution. The results show that the perovskite with foreign fullerene derivative (PCBM) additive can suppress hysteresis behavior and increase the mobility by two-fold, while the perovskite with native iodine (I) additive will amplify hysteresis and reduce the mobility by two orders of magnitude at the room temperature compared with that of the pure perovskite. Furthermore, we found that the response characteristics of the photodetectors are strongly affected by the carrier mobility. Capacitance-voltage results confirm the significant change in hysteresis after the introduction of different additives, which explains the changes in mobility and photoresponse time. Our results enlighten the hysteresis effect related to carrier transport and photoresponse characteristics, and provide guidance for the development of reliable, high performance perovskite devices.

  • 224.
    Parlak, Onur
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Department of Materials Science and Engineering, Stanford University, Stanford, USA.
    Mishra, Yogendra Kumar
    Functional Nanomaterials, Institute for Materials Science, Kiel University, Kiel, Germany.
    Grigoriev, Anton
    Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden.
    Mecklenburg, Matthias
    Institute of Polymers and Composites, Hamburg University of Technology, Hamburg, Germany.
    Luo, Wei
    Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden.
    Keene, Scott
    Department of Materials Science and Engineering, Stanford University, Stanford, USA.
    Salleo, Alberto
    Department of Materials Science and Engineering, Stanford University, Stanford, USA.
    Schulte, Karl
    Institute of Polymers and Composites, Hamburg University of Technology, Hamburg, Germany.
    Ahuja, Rajeev
    Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden.
    Adelung, Rainer
    Functional Nanomaterials, Institute for Materials Science, Kiel University, Kiel, Germany.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Tiwari, Ashutosh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Institute of Advanced Materials, IAAM, Mjärdevi Science Park, UCS, Linköping, Sweden.
    Hierarchical Aerographite Nano-Microtubular Tetrapodal Networks based Electrodes as Lightweight Supercapacitor.2017In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 34, p. 570-577Article in journal (Refereed)
    Abstract [en]

    A great deal of interest has been paid to the application of carbon-based nano- and microstructured materials as electrodes due to their relatively low-cost production, abundance, large surface area, high chemical stability, wide operating temperature range, and ease of processing including many more excellent features. The nanostructured carbon materials usually offer various micro-textures due to their varying degrees of graphitisation, a rich variety in terms of dimensionality as well as morphologies, extremely large surface accessibility and high electrical conductivity, etc. The possibilities of activating them by chemical and physical methods allow these materials to be produced with further higher surface area and controlled distribution of pores from nanoscale upto macroscopic dimensions, which actually play the most crucial role towards construction of the efficient electrode/electrolyte interfaces for capacitive processes in energy storage applications. Development of new carbon materials with extremely high surface areas could exhibit significant potential in this context and motivated by this in present work, we report for the first time the utilization of ultralight and extremely porous nano-microtubular Aerographite  tetrapodal network as a functional interface to probe the electrochemical properties for capacitive energy storage. A simple and robust electrode fabrication strategy based on surface functionalized Aerographite with optimum porosity leads to significantly high specific capacitance (640 F/g) with high energy (14.2 Wh/kg) and power densities (9.67x103 W/kg) which has been discussed in detail.

  • 225.
    Parveen, Nazish
    et al.
    Yeungnam Univ, South Korea.
    Khan, Ziyauddin
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. UNIST, South Korea.
    Ansari, Sajid Ali
    Yeungnam Univ, South Korea; King Faisal Univ, Saudi Arabia.
    Park, Seungyoung
    UNIST, South Korea.
    Senthilkumar, S. T.
    UNIST, South Korea.
    Kim, Youngsik
    UNIST, South Korea.
    Ko, Hyunhyub
    UNIST, South Korea.
    Cho, Moo Hwan
    Yeungnam Univ, South Korea.
    Feasibility of using hollow double walled Mn2O3 nanocubes for hybrid Na-air battery2019In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 360, p. 415-422Article in journal (Refereed)
    Abstract [en]

    Synthesis of the strongly anisotropic materials, such as highly porous hollow double walled cubes are considered excellent approach to maximize the diffusion of electrolytes. Herein, hollow doubled walled (HDW) Mn2O3 nanocubes (NCs) were synthesized by facile hydrothermal method followed by calcination method. The growth of nanocubes were studied by performing hydrothermal reaction at different times ranging from 3 to 9 h. Thereafter, the feasibility of prepared HDW NCs as air cathode in hybrid Na-air battery was systematically investigated. Among all, the sample prepared by 9 h hydrothermal treatment showed superior performance than 3 and 6 h samples. The fabricated hybrid Na-air cell using HDW Mn2O3 NCs displayed 330 mV overpotential gap and 90% electrical energy efficiency at 5 mA g(-1) current density, maximum of 0.2Wg(-1) power density and good cyclic stability up to 75 cycles which is attributed to the highly porous nature of material that allows efficient diffusion of electrolyte ions and oxygen from air. Thus, present investigation suggests that HDW Mn2O3 NCs can be a potential air cathode and can be utilized in other metal-air battery systems.

  • 226.
    Patil, Nagaraj
    et al.
    University of Liege, Belgium.
    Aqil, Abdelhafid
    University of Liege, Belgium.
    Ouhib, Farid
    University of Liege, Belgium.
    Admassie, Shimelis
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Addis Ababa University, Ethiopia.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Jerome, Christine
    University of Liege, Belgium.
    Detrembleur, Christophe
    University of Liege, Belgium.
    Bioinspired Redox-Active Catechol-Bearing Polymers as Ultrarobust Organic Cathodes for Lithium Storage2017In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 29, no 40, article id 1703373Article in journal (Refereed)
    Abstract [en]

    Redox-active catechols are bioinspired precursors for ortho-quinones that are characterized by higher discharge potentials than para-quinones, the latter being extensively used as organic cathode materials for lithium ion batteries (LIBs). Here, this study demonstrates that the rational molecular design of copolymers bearing catechol-and Li+ ion-conducting anionic pendants endow redox-active polymers (RAPs) with ultrarobust electrochemical energy storage features when combined to carbon nanotubes as a flexible, binder-, and metal current collector-free buckypaper electrode. The importance of the structure and functionality of the RAPs on the battery performances in LIBs is discussed. The structure-optimized RAPs can store high-capacities of 360 mA h g(-1) at 5C and 320 mA h g(-1) at 30C in LIBs. The high ion and electron mobilities within the buckypaper also enable to register 96 mA h g(-1) (24% capacity retention) at an extreme C-rate of 600C (6 s for total discharge). Moreover, excellent cyclability is noted with a capacity retention of 98% over 3400 cycles at 30C. The high capacity, superior active-material utilization, ultralong cyclability, and excellent rate performances of RAPs-based electrode clearly rival most of the state-of-the-art Li+ ion organic cathodes, and opens up new horizons for large-scalable fabrication of electrode materials for ultrarobust Li storage.

  • 227.
    Patra, Hirak Kumar
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Sharma, Yashpal
    International Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), Sengen, Tsukuba, Ibaraki, Japan .
    Islam, Mohammad Mirazul
    Swedish Nanoscience Center, Karolinska Institute, Stockholm, Sweden.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Arul Murugan, N.
    Virtual Laboratory for Molecular Probes, Division of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden .
    Kobayashi, Hisatoshi
    International Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), Sengen, Tsukuba, Ibaraki, Japan .
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Tiwari, Ashutosh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. International Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), Sengen, Tsukuba, Ibaraki, Japan ; Tekidag AB, UCS, Linköping, Sweden; Vinoba Bhave Research Institute, Saidabad, Allahabad, India .
    Inflammation-sensitive in situ smart scaffolding for regenerative medicine2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 39, p. 17213-17222Article in journal (Refereed)
    Abstract [en]

    To cope with the rapid evolution of the tissue engineering field, it is now essential to incorporate the use of on-site responsive scaffolds. Therefore, it is of utmost importance to find new Intelligent biomaterials that can respond to the physicochemical changes in the microenvironment. In this present report, we have developed biocompatible stimuli responsive polyaniline-multiwalled carbon nanotube/poly(N-isopropylacrylamide), (PANI-MWCNT/PNIPAm) composite nanofiber networks and demonstrated the physiological temperature coordinated cell grafting phenomenon on its surface. The composite nanofibers were prepared by a two-step process initiated with an assisted in situ polymerization followed by electro-spinning. To obtain a smooth surface in individual nanofibers with the thinnest diameter, the component ratios and electrospinning conditions were optimized. The temperature-gated rearrangements of the molecular structure are characterized by FTIR spectroscopy with simultaneous macromolecular architecture changes reflected on the surface morphology, average diameter and pore size as determined by scanning electron microscopy. The stimuli responsiveness of the nanofibers has first been optimized with computational modeling of temperature sensitive components (coil-like and globular conformations) to tune the mechanism for temperature dependent interaction during in situ scaffolding with the cell membrane. The nanofiber networks show excellent biocompatibility, tested with fibroblasts and also show excellent sensitivity to inflammation to combat loco-regional acidosis that delay the wound healing process by an in vitro model that has been developed for testing the proposed responsiveness of the composite nanofiber networks. Cellular adhesion and detachment are regulated through physiological temperature and show normal proliferation of the grafted cells on the composite nanofibers. Thus, we report for the first time, the development of physiological temperature gated inflammation-sensitive smart biomaterials for advanced tissue regeneration and regenerative medicine.

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  • 228.
    Persson, Ingemar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    El Ghazaly, Ahmed
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tao, Quanzheng
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kota, Sankalp
    Drexel Univ, PA 19104 USA.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barsoum, Michel W.
    Drexel Univ, PA 19104 USA.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tailoring Structure, Composition, and Energy Storage Properties of MXenes from Selective Etching of In-Plane, Chemically Ordered MAX Phases2018In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 14, no 17, article id 1703676Article in journal (Refereed)
    Abstract [en]

    The exploration of 2D solids is one of our times generators of materials discoveries. A recent addition to the 2D world is MXenes that possses a rich chemistry due to the large parent family of MAX phases. Recently, a new type of atomic laminated phases (coined i-MAX) is reported, in which two different transition metal atoms are ordered in the basal planes. Herein, these i-MAX phases are used in a new route for tailoriong the MXene structure and composition. By employing different etching protocols to the parent i-MAX phase (Mo2/3Y1/3)(2)AlC, the resulting MXene can be either: i) (Mo2/3Y1/3)(2)C with in-plane elemental order through selective removal of Al atoms or ii) Mo1.33C with ordered vacancies through selective removal of both Al and Y atoms. When (Mo2/3Y1/3)(2)C (ideal stoichiometry) is used as an electrode in a supercapacitor-with KOH electrolytea volumetric capacitance exceeding 1500 F cm(-3) is obtained, which is 40% higher than that of its Mo1.33C counterpart. With H2SO4, the trend is reversed, with the latter exhibiting the higher capacitance (approximate to 1200 F cm(-3)). This additional ability for structural tailoring will indubitably prove to be a powerful tool in property-tailoring of 2D materials, as exemplified here for supercapacitors.

  • 229.
    Persson, Ingemar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hansen, Thomas W.
    DTU Danchip CEN, Denmark.
    Wagner, Jakob B.
    DTU Danchip CEN, Denmark.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    How Much Oxygen Can a MXene Surface Take Before It Breaks?2020In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, article id 1909005Article in journal (Refereed)
    Abstract [en]

    Tuning and tailoring of surface terminating functional species hold the key to unlock unprecedented properties for a wide range of applications of the largest 2D family known as MXenes. However, a few routes for surface tailoring are explored and little is known about the extent to which the terminating species can saturate the MXene surfaces. Among available terminations, atomic oxygen is of interest for electrochemical energy storage, hydrogen evolution reaction, photocatalysis, etc. However, controlled oxidation of the surfaces is not trivial due to the favored formation of oxides. In the present contribution, single sheets of Ti3C2Tx MXene, inherently terminated by F and O, are defluorinated by heating in vacuum and subsequentially exposed to O-2 gas at temperatures up to 450 degrees C in situ, in an environmental transmission electron microscope. Results include exclusive termination by O on the MXene surfaces and eventual supersaturation (x amp;gt; 2) with a retained MXene sheet structure. Upon extended O exposure, the MXene structure transforms into TiO2 and desorbs surface bound H2O and CO2 reaction products. These results are fundamental for understanding the oxidation, the presence of water on MXene surfaces, and the degradation of MXenes, and pave way for further tailoring of MXene surfaces.

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  • 230.
    Persson, Ingemar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lind, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hansen, Thomas W.
    Tech Univ Denmark DTU, Denmark.
    Wagner, Jakob B.
    Tech Univ Denmark DTU, Denmark.
    Näslund, Lars-Åke
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    2D Transition Metal Carbides (MXenes) for Carbon Capture2019In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 31, no 2, article id 1805472Article in journal (Refereed)
    Abstract [en]

    Global warming caused by burning of fossil fuels is indisputably one of mankinds greatest challenges in the 21st century. To reduce the ever-increasing CO2 emissions released into the atmosphere, dry solid adsorbents with large surface-to-volume ratio such as carbonaceous materials, zeolites, and metal-organic frameworks have emerged as promising material candidates for capturing CO2. However, challenges remain because of limited CO2/N-2 selectivity and long-term stability. The effective adsorption of CO2 gas (approximate to 12 mol kg(-1)) on individual sheets of 2D transition metal carbides (referred to as MXenes) is reported here. It is shown that exposure to N-2 gas results in no adsorption, consistent with first-principles calculations. The adsorption efficiency combined with the CO2/N-2 selectivity, together with a chemical and thermal stability, identifies the archetype Ti3C2 MXene as a new material for carbon capture (CC) applications.

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    2D Transition Metal Carbides (MXenes) for Carbon Capture
  • 231.
    Persson, Ingemar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Näslund, Lars-Åke
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, PA 19104 USA.
    Barsoum, Michel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, PA 19104 USA.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    On the organization and thermal behavior of functional groups on Ti3C2 MXene surfaces in vacuum2018In: 2D MATERIALS, ISSN 2053-1583, Vol. 5, no 1, article id 015002Article in journal (Refereed)
    Abstract [en]

    The two-dimensional (2D) MXene Ti(3)C(2)Tx is functionalized by surface groups (T-x) that determine its surface properties for, e.g. electrochemical applications. The coordination and thermal properties of these surface groups has, to date, not been investigated at the atomic level, despite strong variations in the MXene properties that are predicted from different coordinations and from the identity of the functional groups. To alleviate this deficiency, and to characterize the functionalized surfaces of single MXene sheets, the present investigation combines atomically resolved in situ heating in a scanning transmission electron microscope (STEM) and STEM simulations with temperature-programmed x-ray photoelectron spectroscopy (TP-XPS) in the room temperature to 750 degrees C range. Using these techniques, we follow the surface group coordination at the atomic level. It is concluded that the F and O atoms compete for the DFT-predicted thermodynamically preferred site and that at room temperature that site is mostly occupied by F. At higher temperatures, F desorbs and is replaced by O. Depending on the O/F ratio, the surface bare MXene is exposed as F desorbs, which enables a route for tailored surface functionalization.

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  • 232.
    Persson, Per O A
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Current state of the art on tailoring the MXene composition, structure, and surface chemistry2019In: Current opinion in solid state & materials science, ISSN 1359-0286, E-ISSN 1879-0348, Vol. 23, no 6, article id UNSP 100774Article, review/survey (Refereed)
    Abstract [en]

    MXenes constitute a family of two-dimensional transition metal carbides, carbonitrides and nitrides. Discovered in 2011, the number of MXenes has expanded significantly and more than 20 different MXenes have been synthesized, with many more predicted from theoretical calculations. MXenes constitute an exceptional family of materials based on their availability for elemental alloying and control of surface terminations, which enables synthesis of a range of structures and chemistries. Consequently, the MXenes exhibit an unparalleled potential for tuning of the materials properties for a wide range of applications. At present, MXenes have emerged with astonishing electronic, optical, plasmonic and thermoelectric properties. This has resulted in a global surge of research around a wide variety of applications, including but not limited to energy storage, carbon capture, electromagnetic interference shielding, reinforcement for composites, water filtering, sensors, and photo-, electro- and chemical catalysis etc. In this review, we present the available state of the art tailoring of the MXene properties owing to recent advances in structural ordering and tuning of surface terminations.

    The full text will be freely available from 2021-09-19 14:30
  • 233.
    Perween, Shama
    et al.
    Rajiv Gandhi Inst Petr Technol, India.
    Khan, Ziyauddin
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. UNIST, South Korea.
    Singh, Somendra
    Rajiv Gandhi Inst Petr Technol, India.
    Ranjan, Amit
    Rajiv Gandhi Inst Petr Technol, India.
    PVA-PDMS-Stearic acid composite nanofibrous mats with improved mechanical behavior for selective filtering applications2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 16038Article in journal (Refereed)
    Abstract [en]

    In this work, we report a facile way to fabricate composite nanofibrous mats of polyvinyl alcohol (PVA), polydimethylsiloxane (PDMS), and stearic acid (SA) by employing the electrospinning-technique, with PDMS fraction ranging from 40w% to nearly 80w%. The results show that for a predetermined fraction of PVA and SA, incorporation of an optimal amount of PDMS is necessary for which the mats exhibit the best mechanical behavior. Beyond this optimal PDMS fraction, the mechanical properties of the composite mats deteriorate. This result has been attributed to the ability of the SA molecules to mediate binding between the PVA and PDMS long-chain molecules via van-der-Waals bonding. The morphological, structural, mechanical, and thermal characterizations respectively using SEM, XRD, DMA/tensile test, and DSC lend support to this explanation. By this method, it is possible to control the hydrophilicity/oleophilicity of the mats, and the mats show an excellent selective permeability to oil as compared to water and successfully filter water from a water-in-oil emulsion. Incorporation of SA not only serves to aid in electrospinning of a PDMS-rich nanofibrous mat with good mechanical strength and control over hydrophilicity/oleophilicity, but also has a potential use in fabricating sheets impregnated with phase change materials for thermal energy storage.

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  • 234.
    Peymanirad, F.
    et al.
    Shahid Rajaee Teacher Training Univ, Iran.
    Singh, Sandeep Kumar
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Ghorbanfekr-Kalashami, H.
    Univ Antwerp, Belgium.
    Novoselov, K. S.
    Univ Manchester, England.
    Peeters, F. M.
    Univ Antwerp, Belgium.
    Neek-Amal, M.
    Shahid Rajaee Teacher Training Univ, Iran; Univ Antwerp, Belgium.
    Thermal activated rotation of graphene flake on graphene2017In: 2D MATERIALS, ISSN 2053-1583, Vol. 4, no 2, article id 025015Article in journal (Refereed)
    Abstract [en]

    The self rotation of a graphene flake over graphite is controlled by the size, initial misalignment and temperature. Using both ab initio calculations and molecular dynamics simulations, we investigate annealing effects on the self rotation of a graphene flake on a graphene substrate. The energy barriers for rotation and drift of a graphene flake over graphene is found to be smaller than 25 meV/atom which is comparable to thermal energy. We found that small flakes (of about similar to 4 nm) are more sensitive to temperature and initial misorientation angles than larger one (beyond 10 nm). The initial stacking configuration of the flake is found to be important for its dynamics and time evolution of misalignment. Large flakes, which are initially in the AA-or AB-stacking state with small misorientation angle, rotate and end up in the AB-stacking configuration. However small flakes can they stay in an incommensurate state specially when the initial misorientation angle is larger than 2 degrees. Our results are in agreement with recent experiments.

  • 235.
    Pilch, Iris
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greiner, Franko
    Christian Albrechts University of Kiel, Germany.
    Diagnostics of void expansion during cyclic growth and formation of layered nanoparticle clouds2017In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 121, no 11, article id 113302Article in journal (Refereed)
    Abstract [en]

    Nanoparticles were grown in an argon-acetylene plasma, and the particle size was characterized during growth using imaging Mie ellipsometry (I-Mie). The typical cyclic growth was observed, and the previously reported expansion and contraction of the void before depletion of nanoparticles [van de Wetering et al., J. Phys. D: Appl. Phys. 48, 035204 (2015)] was independently confirmed in our measurements. The cyclic growth was interrupted by repetitively turning the acetylene flow on and off. The nanoparticles that were confined in the discharge proceeded to grow slowly but more importantly a new growth cycle started with nucleation and growth taking place in the void region. The additional growth burst in the void region leads to a structured dust cloud with regions of nanoparticles with different sizes that were sharply separated. The advantages of using the I-Mie diagnostics for the observation of nanoparticles compared to standard video microscopy are demonstrated for the structured dust cloud. The results are discussed in relation to the growth processes for nucleation and coagulation.

  • 236.
    Pirhashemi, Mahsa
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Univ Mohaghegh Ardabili, Iran.
    Elhag, Sami
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Habibi-Yangjeh, Aziz
    Univ Mohaghegh Ardabili, Iran.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Polyethylene glycol-doped BiZn2VO6 as a high efficiency solar-light-activated photocatalyst with substantial durability toward photodegradation of organic contaminations2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 65, p. 37480-37491Article in journal (Refereed)
    Abstract [en]

    In this study, we focus on a simple, low-priced, and mild condition hydrothermal route to construct BiZn2VO6 nanocompounds (NCs) as a novel photocatalyst with strong solar Eight absorption ability for environmental purification using solar energy. NCs were further doped with polyethylene glycol (PEG) to improve their photocatalytic efficiency for photodegradation processes through inhibition of fast charge carrier recombination rates and higher charge separation efficiency. Surface morphology, phase structure, optical characteristics, and band structure of the as-prepared samples were analyzed using XRD, EDX, XPS, SEM, UV-vis spectroscopy, CL, and BET techniques. PEG-doped BiZn2VO6 NCs were applied as effective materials to degrade various kinds of organic pollutants including cationic and anionic types, and these NCs exhibited excellent photocatalytic efficiency as compared to traditional photocatalysts. In particular, the PEG-doped BiZn2VO6 (0.10% w/v) photocatalyst exhibited highly enhanced photocatalytic performance with improvements of about 46.4, 28.3, and 7.23 folds compared with PEG-doped ZnO nanorods (NRs), pristine BiVO4, and BiZn2VO6 samples, respectively, for the decomposition of congo red (CR) dye. After 40 minutes of sunlight irradiation, 97.4% of CR was decomposed. In this study, scavenging experiments indicated that both hydroxyl radicals and holes play dominant roles in CR photodegradation under simulated solar Eight irradiation. Meanwhile, the optimal photocatalyst demonstrated good reproducibility and stability for successive cycles of photocatalysis.

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  • 237.
    Prieto, German
    et al.
    University of Nacl Sur, Argentina; Consejo Nacl Invest Cient and Tecn, Argentina.
    Bakoglidis, Konstantinos
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tuckart, Walter R.
    University of Nacl Sur, Argentina; Consejo Nacl Invest Cient and Tecn, Argentina.
    Broitman, Esteban
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Nanotribological behavior of deep cryogenically treated martensitic stainless steel2017In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 8, p. 1760-1768Article in journal (Refereed)
    Abstract [en]

    Cryogenic treatments are increasingly used to improve the wear resistance of various steel alloys by means of transformation of retained austenite, deformation of virgin martensite and carbide refinement. In this work the nanotribological behavior and mechanical properties at the nano-scale of cryogenically and conventionally treated AISI 420 martensitic stainless steel were evaluated. Conventionally treated specimens were subjected to quenching and annealing, while the deep cryogenically treated samples were quenched, soaked in liquid nitrogen for 2 h and annealed. The elastic- plastic parameters of the materials were assessed by nanoindentation tests under displacement control, while the friction behavior and wear rate were evaluated by a nanoscratch testing methodology that it is used for the first time in steels. It was found that cryogenic treatments increased both hardness and elastic limit of a low-carbon martensitic stainless steel, while its tribological performance was enhanced marginally.

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  • 238.
    Qin, Leiqian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Tao, Quanzheng
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Jinan Univ, Peoples R China.
    Polymer-MXene composite films formed by MXene-facilitated electrochemical polymerization for flexible solid-state microsupercapacitors2019In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, p. 734-742Article in journal (Refereed)
    Abstract [en]

    Materials with tailored properties are crucial for high performance electronics applications. Hybrid materials composed of inorganic and organic components can possess unique merits for broad application by synergy between the advantages the respective material type offers. Here we demonstrate a novel electrochemical polymerization (EP) enabled by a 2D transition metal carbide MXene for obtaining conjugated polymer-MXene composite films deposited on conducting substrates without using traditional electrolytes, indispensable compounds for commonly electrochemical polymerization. The universality of the process provides a novel approach for EP allowing fast facile process for obtaining different new polymer/MXene composites with controlled thickness and micro-pattern. Furthermore, high performance microsupercapacitors and asymmetric microsupercapacitors are realized based on the excellent composites benefiting from higher areal capacitance, better rate capabilities and lower contact resistance than conventional electropolymerized polymers. The AMSCs exhibit a maximum areal capacitance of 69.5 mF cm(-2), an ultrahigh volumetric energy density (250.1 mWh cm(-3)) at 1.6 V, and excellent cycling stability up to 10000 cycles. The excellent electrochemical properties of the composite polymerized with MXene suggest a great potential of the method for various energy storage applications.

    The full text will be freely available from 2021-04-05 08:38
  • 239.
    Qing, Jian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Shenzhen Univ, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Heyong
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Yuming
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xiaoke
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Li, Mingjie
    Nanyang Technol Univ, Singapore.
    Sum, Tze Chien
    Nanyang Technol Univ, Singapore.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Zhang, Wenjing
    Shenzhen Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    High-Quality Ruddlesden-Popper Perovskite Films Based on In Situ Formed Organic Spacer Cations2019In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, article id 1904243Article in journal (Refereed)
    Abstract [en]

    Ruddlesden-Popper perovskites (RPPs), consisting of alternating organic spacer layers and inorganic layers, have emerged as a promising alternative to 3D perovskites for both photovoltaic and light-emitting applications. The organic spacer layers provide a wide range of new possibilities to tune the properties and even provide new functionalities for RPPs. However, the preparation of state-of-the-art RPPs requires organic ammonium halides as the starting materials, which need to be ex situ synthesized. A novel approach to prepare high-quality RPP films through in situ formation of organic spacer cations from amines is presented. Compared with control devices fabricated from organic ammonium halides, this new approach results in similar (and even better) device performance for both solar cells and light-emitting diodes. High-quality RPP films are fabricated based on different types of amines, demonstrating the universality of the approach. This approach not only represents a new pathway to fabricate efficient devices based on RPPs, but also provides an effective method to screen new organic spacers with further improved performance.

    The full text will be freely available from 2020-08-28 15:10
  • 240.
    Rafique, Asia
    et al.
    COMSATS Univ Islamabad, Pakistan; Govt Punjab, Pakistan.
    Ahmad, Muhammad Ashfaq
    COMSATS Univ Islamabad, Pakistan.
    Shakir, Imran
    King Saud Univ, Saudi Arabia.
    Ali, Amjad
    COMSATS Univ Islamabad, Pakistan; Univ Okara, Pakistan.
    Abbas, Ghazanfar
    COMSATS Univ Islamabad, Pakistan.
    Javed, Muhammad Sufyan
    Jinan Univ, Peoples R China.
    Khan, M. Ajmal
    COMSATS Univ Islamabad, Pakistan.
    Raza, Rizwan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. COMSATS Univ Islamabad, Pakistan.
    Multioxide phase-based nanocomposite electrolyte (M@SDC where M = Zn2+ / Ba2+/ La2+/Zr-2/Al3+) materials2020In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 46, no 52, p. 6882-6888Article in journal (Refereed)
    Abstract [en]

    This paper deals with the development of a highly dense and stable electrolyte on the base of nanoionics oxide interface theory. This gives a comparative study of two-phase nanocomposite electrolytes that are developed for low temperature solid oxide fuel cells (LT-SOFCs). These nanocomposites are synthesised with different oxides, which are coated on the doped ceria that showed high oxide ion mobility for LT-SOFCs. These novel two-phase nanocomposite oxide ionic conductors (MCe0.8Sm0.2O2-MO2, where M = Zn2+/Ba2+/La3+/Zr2+/Al3+) were synthesised by a co-precipitation method. The interface study between these two phases was analysed by electrochemical impedance spectroscopy (EIS), while ionic conductivities were measured with DC conductivity (four probe method). The nanocomposite electrolytes exhibited higher conductivities with the increase of concentration of coated oxides but decreased at a certain level. The structural or morphological properties of the nanocomposite electrolytes were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability was investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The maximum performance of 590 mW/cm(2) at 550 degrees C was obtained for the Zn@SDC based cell, and the rest of the coated samples Ba@SDC, La@SDC, Zr@SDC and Al@SDC based cells showed values of 550 mW/cm(2), 540 mW/cm(2), 450 mW/cm(2), 340 mW/cm(2), respectively, with hydrogen as a fuel. Therefore, the coated-SDC based nanocomposite materials are a good approach for lowering the operating temperature to achieve the challenges of the solid oxide fuel cells (SOFC). These two-phase nanocomposite electrolytes satisfy the all requirements which one electrolyte should have, like high ionic conduction, thermodynamic stability and negligible electronic conduction.

  • 241.
    Rafique, Asia
    et al.
    COMSATS Univ Islamabad, Pakistan; Govt Punjab, Pakistan.
    Raza, Rizwan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. COMSATS Univ Islamabad, Pakistan.
    Ali, Amjad
    COMSATS Univ Islamabad, Pakistan; Univ Okara, Pakistan.
    Ahmad, Muhammad Ashfaq
    COMSATS Univ Islamabad, Pakistan.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    An efficient carbon resistant composite Ni0.6Zn0.4O2-delta-GDC anode for biogas fuelled solid oxide fuel cell2019In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 438, article id 227042Article in journal (Refereed)
    Abstract [en]

    This paper describes the fabrication of Ni0.6Zn0.4-Gd0.2Ce0.8O2-delta (NiZn-GDC) via a two-step wet chemical synthesis technique. This composite was found to be more thermally stable and carbon resistive under the intense reducing environment of biogas. This was confirmed by different characterization techniques. The maximum power density P-max, was achieved at 600 degrees C as 820 mW/cm(2) and 548 mW/cm(2) with hydrogen and biogas, respectively. Different characterization techniques have been performed, such as X-ray diffractometry (XRD), scanning electron microscopy (SEM/EDX), UV visible spectroscopy, and Raman spectroscopy. The XRD pattern by Rietveld refinement showed two-phase structures of the anode composite with an average crystallite size of 25 35 nm before and after reduction with methane. The optical band gap (E-g(opt)) of NiZn-GDC was calculated to be 2.24eV from the Tauc plot using absorbance data. The Nyquist plot was also drawn to study the AC electrochemical impedance spectra (EIS) of the nanocomposite anode from 450 degrees C to 600 degrees C in air. The maximum DC conductivity of 1.37 S/cm was observed at a temperature of 600 degrees C using the four-probe DC technique.

  • 242.
    Rastgoo-Lahrood, Atena
    et al.
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Lischka, Matthias
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Eichhorn, Johanna
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Kloft, Stephan
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Fritton, Massimo
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Strunskus, Thomas
    University of Kiel, Germany.
    Samanta, Debabrata
    University of Siegen, Germany.
    Schmittel, Michael
    University of Siegen, Germany.
    Heckl, Wolfgang M.
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Lackinger, Markus
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Post-Synthetic Decoupling of On-Surface-Synthesized Covalent Nanostructures from Ag(111)2016In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, no 27, p. 7650-7654Article in journal (Refereed)
    Abstract [en]

    The on-surface synthesis of covalent organic nanosheets driven by reactive metal surfaces leads to strongly adsorbed organic nanostructures, which conceals their intrinsic properties. Hence, reducing the electronic coupling between the organic networks and commonly used metal surfaces is an important step towards characterization of the true material. We demonstrate that post-synthetic exposure to iodine vapor leads to the intercalation of an iodine monolayer between covalent polyphenylene networks and Ag(111) surfaces. The experimentally observed changes from surface-bound to detached nanosheets are reproduced by DFT simulations. These findings suggest that the intercalation of iodine provides a material that shows geometric and electronic properties substantially closer to those of the freestanding network.

  • 243.
    Rehmen, Junaiz
    et al.
    Univ South Australia, Australia.
    Zuber, Kamil
    Univ South Australia, Australia.
    Modarresi, Mohsen
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering. Ferdowsi Univ Mashhad, Iran.
    Kim, Donghyun
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Charrault, Eric
    Univ South Australia, Australia.
    Jannasch, Patric
    Lund Univ, Sweden.
    Zozoulenko, Igor
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Evans, Drew
    Univ South Australia, Australia.
    Karlsson, Christoffer
    Lund Univ, Sweden.
    Structural Control of Charge Storage Capacity to Achieve 100% Doping in Vapor Phase-Polymerized PEDOT/Tosylate2019In: ACS OMEGA, ISSN 2470-1343, Vol. 4, no 26, p. 21818-21826Article in journal (Refereed)
    Abstract [en]

    Vapor phase polymerization (VPP) is used to fabricate a series of tosylate-doped poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes on carbon paper. The series of VPP PEDOT/tosylate coatings has varying levels of crystallinity and electrical conductivity because of the use (or not) of nonionic triblock copolymers in the oxidant solution during synthesis. As a result, the impact of the structure on charge storage capacity is investigated using tetra-n-butylammonium hexafluorophosphate (0.1 M in acetonitrile). The ability to insert anions, and hence store charge, of the VPP PEDOT/tosylate is inversely related to its electrical conductivity. In the case of no nonionic triblock copolymer employed, the VPP PEDOT/tosylate achieves electrochemical doping levels of 1.0 charge per monomer or greater (amp;gt;= 100% doping level). Such high doping levels are demonstrated to be plausible by molecular dynamics simulations and density functional theory calculations. Experiments show that this high doping level is attainable when the PEDOT structure is weakly crystalline with (relatively) large crystallite domains.

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  • 244.
    Ren, Chang E.
    et al.
    Drexel University, USA.
    Zhao, Meng-Qiang
    Drexel University, USA.
    Makaryan, Taron
    Drexel University, USA.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, USA.
    Boota, Muhammad
    Drexel University, USA.
    Kota, Sankalp
    Drexel University, USA.
    Anasori, Babak
    Drexel University, USA.
    Barsoum, Michel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, USA.
    Gogotsi, Yury
    Drexel University, USA.
    Porous Two-Dimensional Transition Metal Carbide (MXene) Flakes for High-Performance Li-Ion Storage2016In: CHEMELECTROCHEM, ISSN 2196-0216, Vol. 3, no 5, p. 689-693Article in journal (Refereed)
    Abstract [en]

    Herein we develop a chemical etching method to produce porous two-dimensional (2D) Ti3C2Tx MXenes at room temperature in aqueous solutions. The as-produced porous Ti3C2Tx (p-Ti3C2Tx) have larger specific surface areas and more open structures than their pristine counterparts, and can be fabricated into flexible films with, or without, the addition of carbon nanotubes (CNTs). The as-fabricated p-Ti3C2Tx/CNT films showed significantly improved lithium ion storage capabilities compared to pristine Ti3C2Tx based films, with a very high capacity of approximate to 1250 mAhg(-1) at 0.1 C, excellent cycling stability, and good rate performance (330 mAhg(-1) at 10 C). Using the same chemical etching method, we also made porous Nb2CTx and V2CTx MXenes. Therefore, this study provides a simple, yet effective, procedure to introduce pores into MXenes and possibly other 2D sheets that in turn, can enhance their electrochemical properties.

  • 245. Order onlineBuy this publication >>
    Rodner, Marius
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Towards a versatile gas sensing platform with epitaxial graphene2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work presented in this thesis focuses on how to utilize epitaxially grown graphene on SiC as a basis for ultra-sensitive gas sensor. Several approaches have been tested and evaluated to increase the sensitivity, selectivity, speed of response and stability and of the graphene based gas sensors with a focus on air quality monitoring applications. The graphene surfaces have been functionalized with different metal oxide nanoparticles and nanolayers using hollow-cathode sputtering and pulsed laser deposition. The modified surface was investigated towards its topography, integrity and chemical composition with characterization methods such as AFM, Raman and XPS. Moreover, the binding energy was calculated with density functional theory for benzene and formaldehyde when reacting with pristine epitaxial graphene and iron oxide nanoparticle decorated graphene to verify the usefulness of this approach. The impact of environmental influences such as operating temperature, relative humidity and UV irradiation towards sensing properties was investigated as well. To further decrease time constants, the first-order time-derivative of the sensor’s resistance is introduced as an alternative sensor signal and evaluated towards its applicability.

    Applying these methods in laboratory conditions, sensors with a quantitative readout of single ppb benzene and formaldehyde were developed and time constants of less than one minute could be achieved with the first-order time-derivative signal. These results show promise to fill the existing gap of low-cost but highly sensitive and fast gas sensors for air quality monitoring.

    List of papers
    1. Performance tuning of gas sensors based on epitaxial graphene on silicon carbide
    Open this publication in new window or tab >>Performance tuning of gas sensors based on epitaxial graphene on silicon carbide
    Show others...
    2018 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 153, p. 153-158Article in journal (Refereed) Published
    Abstract [en]

    In this study, we investigated means of performance enhancement in sensors based on epitaxial graphene on silicon carbide (SiC). Epitaxially grown graphene on SiC substrates were successfully decorated with metal oxide nanoparticles such as TiO2 and Fe3O4 using hollow cathode pulsed plasma sputtering. Atomic Force Microscopy and Raman data verified that no damage was added to the graphene surface. It could be shown that it was easily possible to detect benzene, which is one of the most dangerous volatile organic compounds, with the Fe3O4 decorated graphene sensor down to an ultra-low concentration of 5 ppb with a signal to noise ratio of 35 dB. Moreover, upon illumination with a UV light LED (265 nm) of the TiO2 decorated graphene sensor, the sensitivity towards a change of oxygen could be enhanced such that a clear sensor response could be seen which is a significant improvement over dark conditions, where almost no response occurred. As the last enhancement, the time derivative sensor signal was introduced for the sensor data evaluation, testing the response towards a change of oxygen. This sensor signal evaluation approach can be used to decrease the response time of the sensor by at least one order of magnitude. (C) 2018 Elsevier Ltd. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER SCI LTD, 2018
    Keywords
    Epitaxial graphene; Metal oxide nanoparticles; Gas sensor; UV light; Derivative sensor signal; Benzene
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-149676 (URN)10.1016/j.matdes.2018.04.087 (DOI)000436433600016 ()
    Note

    Funding Agencies|Swedish Foundation for Strategic research (SSF) [GMT14-0077]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; Centre in Nano science and technology (CeNano)

    Available from: 2018-07-25 Created: 2018-07-25 Last updated: 2019-09-23
    2. Graphene Decorated with Iron Oxide Nanoparticles for Highly Sensitive Interaction with Volatile Organic Compounds
    Open this publication in new window or tab >>Graphene Decorated with Iron Oxide Nanoparticles for Highly Sensitive Interaction with Volatile Organic Compounds
    Show others...
    2019 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 19, no 4, article id 918Article in journal (Refereed) Published
    Abstract [en]

    Gases, such as nitrogen dioxide, formaldehyde and benzene, are toxic even at very low concentrations. However, so far there are no low-cost sensors available with sufficiently low detection limits and desired response times, which are able to detect them in the ranges relevant for air quality control. In this work, we address both, detection of small gas amounts and fast response times, using epitaxially grown graphene decorated with iron oxide nanoparticles. This hybrid surface is used as a sensing layer to detect formaldehyde and benzene at concentrations of relevance (low parts per billion). The performance enhancement was additionally validated using density functional theory calculations to see the effect of decoration on binding energies between the gas molecules and the sensor surface. Moreover, the time constants can be drastically reduced using a derivative sensor signal readout, allowing the sensor to work at detection limits and sampling rates desired for air quality monitoring applications.

    Place, publisher, year, edition, pages
    MDPI, 2019
    Keywords
    epitaxial graphene; metal oxide nanoparticle; gas sensor; volatile organic compounds; benzene; formaldehyde; derivative sensor signal; air quality sensor
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-155940 (URN)10.3390/s19040918 (DOI)000460829200169 ()30813225 (PubMedID)
    Note

    Funding Agencies|Swedish Foundation for Strategic research (SSF) [GMT14-0077, RMA15-024]; Knut and Alice Wallenberg Foundation [KAW14.0276, 2012.0083]; Centre in Nano science and technology (CeNano) through the project "Graphene-nanoparticle hybrid gas sensor"; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Angpanneforeningens Forskningsstiftelse [16-541]; Hans Werthen Foundation grant

    Available from: 2019-04-01 Created: 2019-04-01 Last updated: 2019-10-15
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  • 246.
    Rodner, Marius
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Bahonjic, Jasna
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Mathisen, Marcus
    Not Found:Linkoping Univ, IFM, Appl Sensor Sci Unit, Linkoping, Sweden.
    Gunnarsson, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Ekeroth, Sebastian
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Performance tuning of gas sensors based on epitaxial graphene on silicon carbide2018In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 153, p. 153-158Article in journal (Refereed)
    Abstract [en]

    In this study, we investigated means of performance enhancement in sensors based on epitaxial graphene on silicon carbide (SiC). Epitaxially grown graphene on SiC substrates were successfully decorated with metal oxide nanoparticles such as TiO2 and Fe3O4 using hollow cathode pulsed plasma sputtering. Atomic Force Microscopy and Raman data verified that no damage was added to the graphene surface. It could be shown that it was easily possible to detect benzene, which is one of the most dangerous volatile organic compounds, with the Fe3O4 decorated graphene sensor down to an ultra-low concentration of 5 ppb with a signal to noise ratio of 35 dB. Moreover, upon illumination with a UV light LED (265 nm) of the TiO2 decorated graphene sensor, the sensitivity towards a change of oxygen could be enhanced such that a clear sensor response could be seen which is a significant improvement over dark conditions, where almost no response occurred. As the last enhancement, the time derivative sensor signal was introduced for the sensor data evaluation, testing the response towards a change of oxygen. This sensor signal evaluation approach can be used to decrease the response time of the sensor by at least one order of magnitude. (C) 2018 Elsevier Ltd. All rights reserved.

    Download full text (pdf)
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  • 247.
    Rogowski, Rafal Z.
    et al.
    Eindhoven University of Technology, Netherlands; Dutch Polymer Institute, Netherlands.
    Dzwilewski, Andrzej
    Eindhoven University of Technology, Netherlands.
    Kemerink, Martijn
    Eindhoven University of Technology, Netherlands.
    Darhuber, Anton A.
    Eindhoven University of Technology, Netherlands.
    Solution Processing of Semiconducting Organic Molecules for Tailored Charge Transport Properties2011In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 23, p. 11758-11762Article in journal (Refereed)
    Abstract [en]

    We studied the charge transport characteristics of the organic semiconductor 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-PEN) deposited by dip-coating of a solution in an azeotropic solvent mixture. Arrays of crystalline ribbons were obtained with a morphology controllable by variation of the coating speed U. The charge carrier mobility mu, exhibited a systematic and reproducible dependence on the coating speed U and maximum values as high as mu approximate to 1.0 cm(2)/(V s).

  • 248.
    Rudko, G.Yu
    et al.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, prospect Nauky, Kyiv, Ukraine.
    Vorona, I. P.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, prospect Nauky, Kyiv, Ukraine.
    Dzhagan, V. M.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, prospect Nauky, Kyiv, Ukraine.
    Raevskaya, A. E.
    L. Pysarzhevsky Institute of Physical Chemistry, National Academy of Sciences of Ukraine, prospect Nauky, Kyiv, Ukraine.
    Stroyuk, O. L.
    L. Pysarzhevsky Institute of Physical Chemistry, National Academy of Sciences of Ukraine, prospect Nauky, Kyiv, Ukraine.
    Fediv, V. I.
    Bukovinian State Medical University, Chernivtsi, Ukraine.
    Kovalchuk, A. O.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, prospect Nauky, Kyiv, Ukraine.
    Stehr, Jan Eric
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Optically detected magnetic resonance study of relaxation/emission processes in the nanoparticle-polymer composite2019In: SPQEO, ISSN 1605-6582, Vol. 22, no 3, p. 310-318Article in journal (Refereed)
    Abstract [en]

    Two nanocomposites containing CdS nanoparticles in polymeric matrices were studied using the photoluminescence (PL) and optically detected magnetic resonance (ODMR) methods. Due to equal sizes of NPs in the composites (~5 nm) but different matrices – the oxygen-containing polymer PVA (polyvinyl alcohol) and oxygen-free polymer PEI (polyethyleneimine) – differences of nanocomposites properties are predominantly caused by different interfacial conditions. ODMR spectra have revealed five types of centers related to the PL emission – four centers involved in radiative recombination and one center related to non-radiative recombination processes. The oxygen-related interfacial center in CdS/PVA (LK1-center) and sulfur vacancy center in CdS/PEI (Vs-center) were identified.

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  • 249.
    Ruoko, Tero-Petri
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering. Chemistry and Advanced Materials, Laboratory of Chemistry and Bioengineering,Tampere University of Technology, Tampere, Finland..
    Hiltunen, Arto
    Tampere Univ Technol, Finland.
    Iivonen, Tomi
    Univ Helsinki, Finland.
    Ulkuniemi, Riina
    Tampere Univ Technol, Finland.
    Lahtonen, Kimmo
    Tampere Univ Technol, Finland.
    Ali-Loeytty, Harri
    Tampere Univ Technol, Finland.
    Mizohata, Kenichiro
    Univ Helsinki, Finland.
    Valden, Mika
    Tampere Univ Technol, Finland.
    Leskelae, Markku
    Univ Helsinki, Finland.
    Tkachenko, Nikolai V.
    Tampere Univ Technol, Finland.
    Charge carrier dynamics in tantalum oxide overlayered and tantalum doped hematite photoanodes2019In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 7, p. 3206-3215Article in journal (Refereed)
    Abstract [en]

    We employ atomic layer deposition to prepare 50 nm thick hematite photoanodes followed by passivating them with a 0.5 nm thick Ta2O5-overlayer and compare them with samples uniformly doped with the same amount of tantalum. We observe a three-fold improvement in photocurrent with the same onset voltage using Ta-overlayer hematite photoanodes, while electrochemical impedance spectroscopy under visible light irradiation shows a decreased amount of surface states under water splitting conditions. The Tadoped samples have an even higher increase in photocurrent along with a 0.15 V cathodic shift in the onset voltage and decreased resistivity. However, the surface state capacitance for the Ta-doped sample is twice that of the reference photoanode, which implies a larger amount of surface hole accumulation. We further utilize transient absorption spectroscopy in the sub-millisecond to second timescale under operating conditions to show that electron trapping in both Ta2O5-passivated and Ta-doped samples is markedly reduced. Ultrafast transient absorption spectroscopy in the sub-picosecond to nanosecond timescale shows faster charge carrier dynamics and reduced recombination in the Ta-doped hematite photoanode resulting in the increased photoelectrochemical performance when compared with the Ta2O5-overlayer sample. Our results show that passivation does not affect the poor charge carrier dynamics intrinsic to hematite based photoanodes. The Ta-doping strategy results in more efficient electron extraction, solving the electron trapping issue and leading to increased performance over the surface passivation strategy.

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  • 250.
    Rybakiewicz, Renata
    et al.
    Cardinal Stefan Wyszynski University, Poland; Warsaw University of Technology, Poland.
    Glowacki, Eric
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Skorka, Lukasz
    Warsaw University of Technology, Poland.
    Pluczyk, Sandra
    Silesian Technical University, Poland.
    Zassowski, Pawel
    Silesian Technical University, Poland.
    Hazar Apaydin, Dogukan
    Johannes Kepler University of Linz, Austria.
    Lapkowski, Mieczyslaw
    Silesian Technical University, Poland; Polish Academic Science, Poland.
    Zagorska, Malgorzata
    Warsaw University of Technology, Poland.
    Pron, Adam
    Warsaw University of Technology, Poland.
    Low and High Molecular Mass Dithienopyrrole-Naphthalene Bisimide Donor-Acceptor Compounds: Synthesis, Electrochemical and Spectroelectrochemical Behaviour2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 12, p. 2839-2851Article in journal (Refereed)
    Abstract [en]

    Two low molecular weight electroactive donor-acceptor- donor (DAD)-type molecules are reported, namely naphthalene bisimide (NBI) symmetrically core-functionalized with dithienopyrrole (NBI-(DTP)(2)) and an asymmetric corefunctionalized naphthalene bisimide with dithienopyrrole (DTP) substituent on one side and 2-ethylhexylamine on the other side (NBI-DTP-NHEtHex). Both compounds are characterized by low optical bandgaps (1.52 and 1.65 eV, respectively). NBI-(DTP)(2) undergoes oxidative electropolymeriza-tion giving the electroactive polymer of ambipolar character. Its two-step reversible reduction and oxidation is corroborated by complementary EPR and UV/Vis-NIR spectroelectrochemical investigations. The polymer turned out to be electrochemically active not only in aprotic solvents but also in aqueous electrolytes, showing a distinct photocathodic current attributed to proton reduction. Additionally, poly(NBI-(DTP)(2)) was successfully tested as a photodiode material.

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