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  • 1.
    Aghoutane, Youssra
    et al.
    Biotechnology Agroalimentary and Biomedical Analysis Group, Department of Biology, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco; Sensor Electronic & Instrumentation Group, Department of Physics, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco.
    Diouf, Alassane
    Biotechnology Agroalimentary and Biomedical Analysis Group, Department of Biology, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco; Sensor Electronic & Instrumentation Group, Department of Physics, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Bouchikhi, Benachir
    Sensor Electronic & Instrumentation Group, Department of Physics, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco.
    El Bari, Nezha el bari
    Biotechnology Agroalimentary and Biomedical Analysis Group, Department of Biology, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco.
    Development of a molecularly imprinted polymer electrochemical sensor and its application for sensitive detection and determination of malathion in olive fruits and oils2020In: Bioelectrochemistry, ISSN 1567-5394, E-ISSN 1878-562X, Vol. 132, article id 107404Article in journal (Refereed)
    Abstract [en]

    Malathion (MAL) is an organophosphorus (OP) insecticide. It is a cholinesterase inhibitor, 15 which can pose serious health and environmental problems. In this study, a sensitive and 16 selective molecular imprinted polymer (MIP) based on screen-printed gold electrodes (Au-17 SPE) for MAL detection in olive oils and fruits, was devised. The MIP sensor was prepared 18 using acrylamide as the functional monomer and MAL as the template. Subsequently, the 19 morphology of the electrode surface was studied by scanning electron microscopy (SEM) and 20 atomic force microscopy (AFM). The electrochemical characterization of the developed MIP 21 sensor was performed by cyclic voltammetry (CV), differential pulse voltammetry (DPV), 22 and electrochemical impedance spectroscopy (EIS) techniques. The operational repeatability 23 and stability of the sensor were studied. It was found to have a dynamic concentration range 24 of (0.1 pg mL-1-1000 pg mL-1) and a low limit of detection (LOD) of 0.06 pg mL-1. 25 Furthermore, the sensor was employed to determine MAL content in olive oil with a recovery 26 rate of 87.9% and a relative standard deviation of 8%. It was successfully applied for MAL 27 determination in real samples and promise to open new opportunities for the detection of OP 28 pesticides residues in various food products, as well as in environmental applications.

  • 2.
    Ahmed, Taha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Optical Quantum Confinement in Ultrasmall ZnO and the Effect of Size on Their Photocatalytic Activity2020In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 124, no 11, p. 6395-6404Article in journal (Refereed)
    Abstract [en]

    Zinc oxide is a well-known metal oxide semiconductor with a wide direct band gap that offers a promising alternative to titanium oxide in photocatalytic applications. ZnO is studied here as quantum dots (QDs) in colloidal suspensions, where ultrasmall nanoparticles of ZnO show optical quantum confinement with a band gap opening for particles below 9 nm in diameter from the shift of the band edge energies. The optical properties of growing ZnO QDs are determined with Tauc analysis, and a system of QDs for the treatment and degradation of distributed threats is analyzed using an organic probe molecule, methylene blue, whose UV/vis spectrum is analyzed in some detail. The effect of optical properties of the QDs and the kinetics of dye degradation are quantified for low-dimensional ZnO materials in the range of 3-8 nm and show a substantial increase in photocatalytic activity compared to larger ZnO particles. This is attributed to a combined effect from the increased surface area as well as a quantum confinement effect that goes beyond the increased surface area. The results show a significantly higher photocatalytic activity for the QDs between 3 and 6 nm with a complete decolorization of the organic probe molecule, while QDs from 6 nm and upward in diameter show signs of competing reduction reactions. Our study shows that ultrasmall ZnO particles have a reactivity beyond that which is expected because of their increased surface area and also demonstrates size-dependent reaction pathways, which introduces the possibility for size-selective catalysis.

  • 3.
    Ahmed, Taha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Thyr, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Naim Katea, Sarmad
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Westin, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Phonon–phonon and electron–phonon coupling in nano-dimensional ZnOManuscript (preprint) (Other academic)
    Abstract [en]

    Thermal losses through vibrational coupling are critical bottlenecks limiting several materials classes from reaching their full potential. Altering the phonon–phonon and electron–phonon coupling by controlled suppression of vibrational degrees of freedom through low-dimensionality are promising but still largely unexplored approaches. Here we report a detailed study of the first- and second-order Raman processes as a function of size for low-dimensional ZnO. Wurtzite ZnO nanoparticles were synthesised into 3D frameworks of ZnO crystallites, with tailored crystallite diameters from 10 nm to 150 nm and characterised by electron microscopy, X-ray diffraction and non-resonant and resonant Raman spectroscopy.

    We present a short derivation of how resonance Raman and the relation between the longitudinal optical (LO) phonons can be utilised to quantify the electron–phonon coupling, its merits, and limitations. Theoretical Raman response using density functional theory is corroborating the experimental data in assigning first- and second-order Raman modes. The Lyddane-Sachs-Teller equation was applied to the measured LO–TO split and revealed no change in the ratio between the static and high-frequency dielectric constant with changing ZnO dimension from 10 nm to 150 nm. The second-order Raman revealed a phonon–phonon coupling that generally increased with particle size and markedly so for differential modes. Resonance Raman showed the fundamental LO mode and the 2nd, 3rd, and 4th overtones. The intensity relation between the fundamental LO mode and its overtones enabled the extraction of the change in electron–phonon coupling via the Huang-Rhys parameter as a function of particle size, which showed an increase with particle size.

  • 4.
    Al-Tikriti, Yassir
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Hansson, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Elastic forces give rise to unusual phase transformations in polyelectrolyte gels: A Raman microscopy studyManuscript (preprint) (Other academic)
  • 5. Amombo Noa, Francoise M.
    et al.
    Cheung, Ocean
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Nanotechnology and Functional Materials.
    Åhlén, Michelle
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Nanotechnology and Functional Materials.
    Ahlberg, Elisabet
    Nehla, Priyanka
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Salazar-Alvarez, German
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Ershadrad, Soheil
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Öhrström, Lars R.
    A Hexagon Based Mn(II) Rod Metal-Organic Framework – Structure, SF6 Gas Sorption, Magnetism and Electrochemistry2023In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548XArticle in journal (Refereed)
    Abstract [en]

    A manganese(II) metal-organic framework based on the hexatopic hexakis(4-carboxyphenyl)benzene, cpb6-: [Mn3(cpb)(dmf)3], was solvothermally prepared showing a Langmuir area of 438 m2/g, rapid uptake of sulfur hexafluoride (SF6) as well as electrochemical and magnetic properties, while single crystal diffraction reveals an unusual rod-MOF topology.

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  • 6.
    Andersson, Edvin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Spectroelectrochemical analysis of the Li-ion battery solid electrolyte interphase using simulated Raman spectra2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Lithium Ion Batteries (LIBs) are important in today's society, powering cars and mobile devices. LIBs consist of a negative anode commonly made of graphite, and a positive cathode commonly made from transition metal oxides. Between these electrodes are separators and organic solvent based electrolyte. Due to the high potential of LIBs the electrolyte is reduced at the anode. The electrolyte reduction results in the formation of a layer called the Solid Electrolyte Interphase (SEI), which prohibits the further breakdown of the electrolyte. Despite being researched for over50 years, the composition formation of the SEI is still poorly understood. The aim of this project is to develop strategies for efficient identification and classification of various active and intermediate components in the SEI, to, in turn, gain an understanding of the reactions taking place, which will help find routes to stabilize and tailor the composition of the SEI layer for long-term stability and optimal battery performance. For a model gold/li-ion battery electrolyte system, Raman spectra will be obtained using Surface Enhanced Raman Spectroscopy (SERS) in a spectroelectrochemical application where the voltage of the working gold electrode is swept from high to low potentials. Spectra of common components of the SEI as well as similar compounds will be simulated using Density Functional Theory (DFT). The DFT data is also used to calculate the spontaneity of reactions speculated to form the SEI. The simulated data will be validated by comparing it to experimental spectra from pure substances. The spectroelectrochemical SERS results show a clear formation of Li-carbonate at the SERS substrate, as well as the decomposition of the electrolyte into other species, according to the simulated data. It is however shown that there are several issues when modelling spectra, that makes it harder to correlate the simulated spectra with the spectroelectrochemical spectra. These issues include limited knowledge of the structure of the compounds thought to form on the anode surface, and incorrect choices in simulational parameters. To solve these issues, more work is needed in these areas, and the spectroelectrochemical methods used in this thesis needs to be combined with other experimental methods to narrow down the amount of compounds to be modelled. More work is also needed to avoid impurities in the electrolyte. Impurities leads to a thick inorganic layer which prohibits the observation of species in the organic layer.

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  • 7.
    Anil Kumar, Puri
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Indian Assoc Cultivat Sci, Sch Mat Sci, Kolkata 700032, India..
    Nag, Abhishek
    Indian Assoc Cultivat Sci, Sch Mat Sci, Kolkata 700032, India..
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Das, Ranjan
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Ray, Sugata
    Indian Assoc Cultivat Sci, Sch Mat Sci, Kolkata 700032, India..
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Hossain, Akmal
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Cherian, Dona
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Venero, Diego Alba
    ISIS Neutron & Muon Source, STFC Rutherford Appleton Lab, Didcot OX11 OQX, England..
    DeBeer-Schmitt, Lisa
    Oak Ridge Natl Lab, Large Scale Struct Grp, Neutron Sci Directorate, Oak Ridge, TN 37831 USA..
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Sarma, D. D.
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Magnetic polarons and spin-glass behavior in insulating La1-xSrxCoO3 (x = 0.125 and 0.15)2020In: Physical Review Research, E-ISSN 2643-1564, Vol. 2, no 4, article id 043344Article in journal (Refereed)
    Abstract [en]

    The evolution of magnetic polarons in Sr doped LaCoO3 (La1-xSrxCoO3) single crystal and polycrystalline samples are investigated by employing dc and ac magnetic measurement and small angle neutron scattering (SANS) techniques. The effect of magnetic field and temperature on magnetic polarons is experimentally studied for La0.875Sr0.125CoO3 and La0.85Sr0.15CoO3 compounds that belong to the spin glass insulating regime of the broader compositional phase diagram of this system. Langevin analyses of the isothermal magnetization curves in the notional paramagnetic regime prove the existence of magnetic polarons with large moments. The dc field superimposed ac susceptibility data and the analysis of the glassy dynamics prove that the size of polarons in 15% Sr doped crystal increase as the field is increased while the field effect is not visible in the 12.5% Sr doped crystal. A polycrystalline sample of La0.85Sr0.15CoO3 is analyzed by SANS experiments, which confirm nonzero correlation length at temperatures far above the macroscopic ordering temperature and hence the presence of magnetic polarons.

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  • 8.
    Ansari, Shaquib Rahman
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Hempel, Nele-Johanna
    Univ Copenhagen, Dept Pharm, DK-2100 Copenhagen, Denmark.;Novo Nordisk AS, Global Res Technol, Novo Nordisk Pk 1, DK-2760 Malov, Denmark..
    Asad, Shno
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Bergström, Christel A. S.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Löbmann, Korbinian
    Univ Copenhagen, Dept Pharm, DK-2100 Copenhagen, Denmark..
    Teleki, Alexandra
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Hyperthermia-Induced In Situ Drug Amorphization by Superparamagnetic Nanoparticles in Oral Dosage Forms2022In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 14, no 19, p. 21978-21988Article in journal (Refereed)
    Abstract [en]

    Superparamagnetic iron oxide nanoparticles (SPIONs) generate heat upon exposure to an alternating magnetic field (AMF), which has been studied for hyperthermia treatment and triggered drug release. This study introduces a novel application of magnetic hyperthermia to induce amorphization of a poorly aqueous soluble drug, celecoxib, in situ in tablets for oral administration. Poor aqueous solubility of many drug candidates is a major hurdle in oral drug development. A novel approach to overcome this challenge is in situ amorphization of crystalline drugs. This method facilitates amorphization by molecular dispersion of the drug in a polymeric network inside a tablet, circumventing the physical instability encountered during the manufacturing and storage of conventional amorphous solid dispersions. However, the current shortcomings of this approach include low drug loading, toxicity of excipients, and drug degradation. Here, doped SPIONs produced by flame spray pyrolysis are compacted with polyvinylpyrrolidone and celecoxib and exposed to an AMF in solid state. A design of experiments approach was used to investigate the effects of SPION composition (Zn0.5Fe2.5O4 and Mn0.5Fe2.5O4), doped SPION content (10–20 wt %), drug load (30–50 wt %), and duration of AMF (3–15 min) on the degree of drug amorphization. The degree of amorphization is strongly linked to the maximum tablet temperature achieved during the AMF exposure (r = 0.96), which depends on the SPION composition and content in the tablets. Complete amorphization is achieved with 20 wt % Mn0.5Fe2.5O4 and 30 wt % celecoxib in the tablets that reached the maximum temperature of 165.2 °C after 15 min of AMF exposure. Furthermore, manganese ferrite exhibits no toxicity in human intestinal Caco-2 cell lines. The resulting maximum solubility of in situ amorphized celecoxib is 5 times higher than that of crystalline celecoxib in biorelevant intestinal fluid. This demonstrates the promising capability of SPIONs as enabling excipients to magnetically induce amorphization in situ in oral dosage forms.

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  • 9.
    Ansari, Shaquib Rahman
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Suárez-López, Yael del Carmen
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Thersleff, Thomas
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Katsaros, Ioannis
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Åhlén, Michelle
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Nanotechnology and Functional Materials.
    Karlgren, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Rinaldi-Ramos, Carlos
    Teleki, Alexandra
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Science for Life Laboratory, SciLifeLab.
    A pharmaceutical quality by design approach to develop high-performance nanoparticles for magnetic hyperthermiaManuscript (preprint) (Other academic)
  • 10.
    Araujo, Rafael B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    High-entropy alloy catalysts: Fundamental aspects, promises towards electrochemical NH3 production, and lessons to learn from deep neural networks2023In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 105, article id 108027Article in journal (Refereed)
    Abstract [en]

    A computational approach to judiciously predict high-entropy alloys (HEAs) as an efficient and sustainable material class for the electrochemical reduction of nitrogen is here presented. The approach employs density functional theory (DFT), adsorption energies of N atoms and N2 molecules as descriptors of the catalytic activity and deep neural networks. A probabilistic approach to quantifying the activity of HEA catalysts for nitrogen reduction reaction (NRR) is described, where catalyst elements and concentration are optimized to increase the probability of specific atomic arrangements on the surfaces. The approach provides key features for the effective filtering of HEA candidates without the need for time-consuming calculations. The relationships between activity and selectivity, which correlate with the averaged valence electron concentration and averaged electronegativity of the reference HEA catalyst, are analyzed in terms of sufficient interaction for sustained reactions and, at the same time, for the release of the active site. As a result, a complete list of 3000 HEAs consisting of quinary components of the elements Mo, Cr, Mn, Fe, Co, Ni, Cu, and Zn are reported together with their metrics to rank them from the most likely to the least likely active catalysts for NRR in gas diffusion electrodes, or for the case where non-aqueous electrolytes are utilized to suppress the competing hydrogen evolution reaction. Moreover, the energetic landscape of the electrochemical NRR transformations are computed and compared to the case of Fe. The study also analyses and discusses how the results would translate to liquid-solid reactions in aqueous electrochemical cells, further affected by changes in properties upon hydroxylation, oxygen, hydrogen, and water coverages.

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  • 11.
    Araujo, Rafael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    N-2 adsorption on high-entropy alloy surfaces: unveiling the role of local environments2023In: Journal of Materials Chemistry A, ISSN 2050-7488, E-ISSN 2050-7496, Vol. 11, no 24, p. 12973-12983Article in journal (Refereed)
    Abstract [en]

    Developing highly active catalysts to electrochemically reduce N-2 to NH3 under ambient conditions is challenging but bears the promise of using ammonia as a potential energy vector in sustainable energy technology. One of the scientific challenges concerns the inertness of N-2 emanating from the highly stable triple bonds and the lack of dipole moments, making N-2 fixation on catalytic surfaces difficult. Another critical challenge is that electrons are more prone to reduce hydrogen than N-2 at the surface, forming a scaling relationship where the reduction ability of the catalyst most often benefits hydrogen reduction instead of nitrogen reduction. Here we show that high-entropy alloys (HEA) - a new class of catalysts with vast compositional and structural possibilities, can enhance N-2 fixation. More specifically, we investigate the role of the local environment in the first and second solvation shell of the adsorbing elements in the bond strength between the dinitrogen molecules and the HEA surfaces. Density functional theory using a Bayesian error estimation functional and vdW interactions is employed to clarify the properties dictating the local bonding. The results show that although the main property calibrating the N-2 bond strength is the d-band centers of the adsorbing elements, the value of the d-band centers of the adsorbing elements is further regulated by their local environment, mainly from the elements in the first solvation shell due to electron donor-acceptor interactions. Therefore, there exists a first solvation shell effect of the adsorbing elements on the bond strength between N-2 molecules and the surface of HEAs. The results show that apart from the direct active site, the indirect relation adds further modulation abilities where the local interactions with a breath of metallic elements could be used in HEAs to engineer specific surface environments. This is utilized here to form a strategy for delivering higher bond strength with the N-2 molecules, mitigating the fixation issue. The analysis is corroborated by correlation analysis of the properties affecting the interaction, thus forming a solid framework of the model, easily extendable to other chemical reactions and surface interaction problems.

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  • 12.
    Araujo, Rafael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Newcastle Univ, Sch Nat & Environm Sci, Energy Mat Lab, Newcastle Upon Tyne NE1 7RU, England..
    Supervised AI and Deep Neural Networks to Evaluate High-Entropy Alloys as Reduction Catalysts in Aqueous Environments2024In: ACS Catalysis, E-ISSN 2155-5435, Vol. 14, no 6, p. 3742-3755Article in journal (Refereed)
    Abstract [en]

    Competitive surface adsorption energies on catalytic surfaces constitute a fundamental aspect of modeling electrochemical reactions in aqueous environments. The conventional approach to this task relies on applying density functional theory, albeit with computationally intensive demands, particularly when dealing with intricate surfaces. In this study, we present a methodological exposition of quantifying competitive relationships within complex systems. Our methodology leverages quantum-mechanical-guided deep neural networks, deployed in the investigation of quinary high-entropy alloys composed of Mo-Cr-Mn-Fe-Co-Ni-Cu-Zn. These alloys are under examination as prospective electrocatalysts, facilitating the electrochemical synthesis of ammonia in aqueous media. Even in the most favorable scenario for nitrogen fixation identified in this study, at the transition from O and OH coverage to surface hydrogenation, the probability of N2 coverage remains low. This underscores the fact that catalyst optimization alone is insufficient for achieving efficient nitrogen reduction. In particular, these insights illuminate that system consideration with oxygen- and hydrogen-repelling approaches or high-pressure solutions would be necessary for improved nitrogen reduction within an aqueous environment.

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  • 13.
    Atak, Gamze
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Hacettepe University, Department of Physics Engineering, Ankara, Turkey.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Montero Amenedo, José
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Durability studies of annealed electrochromic tungsten oxide films2021In: EMRS Fall Meeting 2021, 2021Conference paper (Other academic)
    Abstract [en]

    In electrochromic (EC) applications, annealing is a crucial parameter not only for an individual layer but also for a full device. For the fabrication of a complete EC device, indium tin oxide (ITO) is often preferred as a transparent conductor layer. ITO films with high transparency and low electrical resistance are usually obtained by sputtering at high substrate temperatures. Consequently, the effect of high temperature on the EC layers can be very significant during sputtering of the ITO top layer for EC devices consisting of five sputtered layers on a single substrate. The role of annealing of a single layer of WO3 may also be important for EC performance. In the present work, we studied the effects of annealing on the durability of WO3 films. Thin films of WO3 were deposited by reactive DC magnetron sputtering in a mixture of Ar and O2 gases using an oxygen to argon ratio of 0.15. The total gas pressure was set to 4.0 Pa, and the sputtering power was 200 W. The WO3 films were deposited onto (i) unheated glass plates, (ii) such plates pre-coated with transparent and electrically conducting ITO with a sheet resistance of 60 Ω/square, and (iii) glass plates pre-coated with fluorine-doped tin oxide (FTO) with a sheet resistance of 14 Ω/square. Film thicknesses were 300±10 nm. After deposition of the films, the samples were annealed at 150, 300, 450, and 600 °C in ambient air for one h using a heating rate of 10 °C min-1. Cyclic voltammetry (CV) was performed for up to 500 cycles between 2.0 and 4.0 V vs. Li/Li+ at a scan rate of 20 mV s–1. Annealing at temperatures at and above 300 °C resulted in deteriorated electrochromic properties of the WO3 films i.e., a decreased transmittance variation. Charge density and coloration efficiency changes during extended electrochemical cycling were also observed as a function of cycle number and annealing temperature. It was found that the maximum optical transmittance modulation at a wavelength of 528 nm after 500 CV cycles was 69.3% for the film annealed at 150 °C.

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  • 14.
    Atak, Gamze
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Montero Amenedo, José
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Electrochromic tungsten oxide films prepared by sputtering: Optimizing cycling durability by judicious choice of deposition parameters2021In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 367, article id 137233Article in journal (Refereed)
    Abstract [en]

    Thin films of W oxide were prepared by reactive DC magnetron sputtering (5 cm-diameter W target), and their electrochromic (EC) properties were investigated in an electrolyte of LiClO4 in propylene carbonate. The purpose of the study was to elucidate the role of critical deposition parameters-oxygen/argon gas flow ratio for the sputter plasma Gamma, total pressure in the sputter plasma p(tot) , and sputtering power P-s - on the EC performance with foci on electrochemical cycling durability and optical modulation range Delta T. Specifically, we used 0.15 <= Gamma <= 0.90, 5 <= p(tot) <= 30 mTorr, and 200 <= P-s <= 400 W and studied cycling durability for up to 500 voltammetric cycles in the range 2.0-4.0 V vs. Li/Li+ together with optical properties at a wavelength of 528 nm. Most significantly, we discovered that a judicious choice of deposition parameters could yield films with superior cycling durability. Thus a similar to 300 nm-thick film prepared at Gamma = 0.90, p(tot) = 10 mTorr, and P-s = 200 W showed Delta T approximate to 65% after an initial "training" during similar to 100 voltammetric cycles; higher values of p(tot), on the other hand, yielded films whose Delta Ts degraded by similar to 10% during the cycling, and a lower value of p(tot) led to dark films with only marginal electrochromism. Hence our work delineates a pathway towards W oxide films with excellent durability of the EC properties.

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  • 15.
    Atak, Gamze
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Hacettepe University, Department of Physics Engineering, Ankara, Turkey.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Montero Amenedo, José
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    The role of oxygen to argon gas flow ratio on the durability of sputter-deposited electrochromic tungsten oxide films2021In: EMRS Fall Meeting 2021, 2021Conference paper (Other academic)
    Abstract [en]

    Materials that are able to vary their transparency and coloration reversibly when they are subjected to an electrical current or voltage are referred to as “electrochromic” (EC). High optical transmittance modulation and long service lifetime are apparent requirements for EC materials used in smart windows technology. An extended service lifetime is provided by the long-term durability of the materials. One important aspect of durability is the ability to sustain charge transport between the EC film and electrolyte, or between the two EC films in a device, for many hundreds or thousands of cycles without any significant changes in the performance such as optical modulation and inserted-extracted charge. The purpose of this study is to clarify the effects of the oxygen-argon gas flow ratio during sputter deposition on the durability of WO3 films. In this study, the oxygen to argon gas-flow ratio was modulated by setting the O2 flow rate to 7.5, 15.0, 22.5, and 45.0 ml min-1 and using a fixed Ar flow rate of 50 ml min-1. Thus, the oxygen to argon gas-flow ratio was varied from 0.15 to 0.90. The pressure in the sputter plasma was set as 30 mTorr and the sputter power was maintained at 200 W. For durability studies, cyclic voltammetry data were recorded for up to 500 cycles between 2.0 and 4.0 V versus Li/Li+ at a scan rate of 20 mV s-1. High oxygen to argon gas ratio was found to have a positive effect on the EC properties of the films. When the long-term performance of the films was examined, it was seen that all the samples displayed a slow decline of the colored-state transmittance due to ion accumulation in the host material. After 500 color-bleach cycles, the maximum optical transmittance modulation between colored and bleached states at a wavelength of 528 nm was 63.6% when the oxygen to argon gas-flow ratio was 0.90.

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  • 16.
    Atak, Gamze
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Hacettepe University, Department of Physics Engineering, 06800 Beytepe, Ankara, Turkey.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Montero Amenedo, José
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Nitrogen doped W oxide films for electrochromic applications2019In: EMRS Spring Meeting 2019, 2019Conference paper (Refereed)
    Abstract [en]

    Electrochromic (EC) materials are able to change their optical properties such as transmission, absorption and reflection reversibly by application of an external voltage. EC metal oxides are divided into two groups: cathodic (coloring under ion insertion) and anodic (coloring under ion extraction). W oxide is a well-known cathodic EC material and its color changes from transparent to dark blue when ions are inserted.

    A desirable electrochromic material must have and maintain a high optical modulation, high coloration efficiency, fast coloration/bleaching switching kinetics and a stable charge/ discharge reversibility.  In this study, W oxide films with different nitrogen levels were deposited by using reactive DC sputtering onto glass and ITO coated glass in Ar+O2+N2 atmosphere. For all films, the total gas pressure was set to 4.0 Pa, the Ar flow rate was kept at 50 ml/min, and the O2+N2 flow rate was kept at 7.5 ml/min. The optical, structural and electrochromic properties of undoped and N-doped W oxide films were investigated. The optical studies revealed that the average optical transmittance and band gap decreased (from 3.43 to 3.08 eV) due to N doping.  It is shown that a small amount of nitrogen has promising effects on the EC performance (i.e. charge/discharge reversibility, optical modulation, coloration efficiency) of the WO3 films. It is observed that CE values increased by increasing N2 flow rate and its maximum value was 33.8 cm2/C. The maximum ΔT at 537 nm was 73.6% for an optimized N doped W oxide film.

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  • 17.
    Atak, Gamze
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Hacettepe University.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Montero, José
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Granqvist, Claes G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Electrochromism of nitrogen-doped tungsten oxide thin films2020In: Materials Today: Proceedings, E-ISSN 2214-7853, Vol. 33, no 6, p. 2434-2439Article in journal (Refereed)
    Abstract [en]

    Tungsten-oxide-based thin films were prepared by reactive DC magnetron sputtering in the presence ofoxygen and nitrogen. Nitrogen contents up to 12 at.% were documented by Rutherford backscattering spectrometry and time-of-flight elastic recoil detection analysis. Optical and electrochemical measurements showed that films with up to 4 at.% of nitrogen were as transparent as undoped tungsten oxide films and displayed enhanced electrochromic properties manifested in an increase in the coloration efficiency by as much as 20%.

  • 18.
    Atak, Gamze
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Hacettepe Univ, Dept Phys Engn, TR-06800 Ankara, Turkey.
    Ghorai, Sagar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Granqvist, Claes G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Cycling durability and potentiostatic rejuvenation of electrochromic tungsten oxide thin films: Effect of silica nanoparticles in LiClO4-Propylene carbonate electrolytes2023In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 250, article id 112070Article in journal (Refereed)
    Abstract [en]

    Electrochromic (EC) technology allows control of the transmission of visible light and solar radiation through thin-film devices. When applied to “smart” windows, EC technology can significantly diminish energy use for cooling and air conditioning of buildings and simultaneously provide good indoor comfort for the buildings’ occupants through reduced glare. EC “smart” windows are available on the market, but it is nevertheless important that their degradation under operating conditions be better understood and, ideally, prevented. In the present work, we investigated EC properties, voltammetric cycling durability, and potentiostatic rejuvenation of sputter-deposited WO3 thin films immersed in LiClO4–propylene carbonate electrolytes containing up to 3.0 wt% of ∼7-nm-diameter SiO2 nanoparticles. Adding about 1 wt% SiO2 led to a significant improvement in cycling durability in the commonly used potential range of 2.0–4.0 V vs. Li/Li+. Furthermore, X-ray photoemission spectroscopy indicated that O–Si bonds were associated with enhanced durability in the presence of SiO2 nanoparticles.

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  • 19.
    Atak, Gamze
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Hacettepe University, Physics Engineering Department, 06800 Beytepe Ankara, Turkey.
    Montero Amenedo, José
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Granqvist, Claes G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Electrochromic performance of WO3 films with different ITO layers2019In: EMRS Spring Meeting 2019., 2019Conference paper (Other academic)
    Abstract [en]

    Electrochromic (EC) materials are able to change their optical properties such as transmission, absorption and reflection reversibly by application of an external voltage. EC metal oxides are divided into two groups: cathodic (coloring under ion insertion) and anodic (coloring under ion extraction). Tungsten oxide (WO3) is a well-known cathodic EC material and has been intensively studied in the last 30 years. EC materials and devices have been developed as an alternative to passive coating materials for light and heat management. Conventionally, an EC device is a construction with five-layers: transparent conducting oxide (TCO)/cathodic EC/ion conducting layer (liquid, gel or solid)/anodic EC/TCO, either all on one substrate or positioned between two substrates in a laminated configuration. Indium-tin oxide (ITO) coated substrates are used as a TCO electrode in EC applications due to their high conductivity and transparency.

    In this study, we deposited WO3 films onto ITO coated glass substrates with different sheet resistances (15, 30, 60 and 1000 Ω/□) by using DC magnetron sputtering technique. Optical and structural properties of ITO films were investigated. For durability studies, cyclic voltammetry data was recorded for up to 500 cycles between 2.0 and 4.0 V versus Li/Li+ at a scan rate of 20 mV s−1. Chronoamperometry measurements of the WO3 films were also performed. We measured the inserted and extracted charges as well as bleaching and coloring times of WO3 films with different ITO layer properties. Generally, ITO with low resistivity is preferred for the electrochemical measurements while absorption is low in the near-infrared region for ITO with higher resistivity. In this study, it is observed that the ITO with 60 Ω/□ sheet resistance is very suitable for optical and electrochromic measurements.

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  • 20.
    Ayub, Khurram Shahzad
    et al.
    East China Univ Sci & Technol, Sch Resources & Environm Engn, State Environm Protect Key Lab Environm Risk Asse, Shanghai 200237, Peoples R China.;Univ Gujrat, Dept Chem Engn, Hafiz Hayat Campus, Gujrat 50700, Pakistan..
    Zaman, Waqas Qamar
    Natl Univ Sci & Technol NUST, Inst Environm Sci & Engn, H-12 Main Campus, Islamabad 44000, Pakistan..
    Miran, Waheed
    Natl Univ Sci & Technol NUST, Sch Chem & Mat Engn, H-12 Main Campus, Islamabad, Pakistan..
    Ali, Meesam
    Muhammad Nawaz Sharif Univ Engn & Technol, Dept Chem Engn, Multan 60000, Pakistan..
    Abbas, Zain
    East China Univ Sci & Technol, Sch Resources & Environm Engn, State Environm Protect Key Lab Environm Risk Asse, Shanghai 200237, Peoples R China.;Forward Sports Private Ltd, Res Ctr, Sialkot, Pakistan..
    Mushtaq, Umair
    East China Univ Sci & Technol, Sch Resources & Environm Engn, State Environm Protect Key Lab Environm Risk Asse, Shanghai 200237, Peoples R China..
    Shahzad, Asif
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Uppsala Univ, Dept Mat Sci & Engn, Box 534, S-75121 Uppsala, Sweden..
    Yang, Ji
    East China Univ Sci & Technol, Sch Resources & Environm Engn, State Environm Protect Key Lab Environm Risk Asse, Shanghai 200237, Peoples R China.;Shanghai Inst Pollut Control & Ecol Secur, Shanghai 20092, Peoples R China..
    Efficient post-plasma catalytic degradation of toluene via series of Co-Cu/TiO2 catalysts2022In: Research on chemical intermediates (Print), ISSN 0922-6168, E-ISSN 1568-5675, Vol. 48, no 10, p. 4227-4248Article in journal (Refereed)
    Abstract [en]

    Volatile organic compounds (VOCs) represent a very important class of pollutants that causes serious health effects. There is an urgent requirement to establish efficient technologies that can reduce and control VOCs. Non-thermal plasma (NTP) is an emerging technology that can decompose low concentration VOCs. However, the low efficiency and high power cost are major hindrances in its commercialization. In this work, Co-Cu with TiO2 support catalysts are prepared by using the deposition precipitation method and utilized in post-plasma catalysis for the efficient degradation of toluene selected as a model VOC. The synergistic effect of Co-Cu/TiO(2)with different Co/Cu molar ratios along with pure Co/TiO2 and Cu/TiO2 catalysts are studied for their catalytic activity. Results showed that the degradation efficiency of toluene for the control experiments (plasma-alone) increased from 10 to 85% with the increase in input power from 11 to 44 W. In comparison, a significant improvement in the degradation efficiency is achieved with post-plasma catalysis owing to better physicochemical properties such as particle surface area and microstructures of the Co-Cu/TiO(2)catalysts. The Co-50-Cu-50/TiO2 exhibited highest degradation efficiency of toluene, i.e. 55% being 5.5 times higher than control at lowest input power of 11 W while 96% at the highest input power of 44 W, attributed to interaction of Co and Cu species, adsorbed oxygen content, and redox properties by exchange of pairs Co+3/Co+2 and Cu+2/Co+3. In summary, the post-plasma catalysis integrated with Co-50-Cu-50/TiO2 catalyst rendered optimal outcomes in terms of power consumption and degradation of VOCs, envisioning commercial viability. [GRAPHICS] .

  • 21.
    Azimi Mousolou, Vahid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Isfahan, Fac Math & Stat, Dept Appl Math & Comp Sci, Esfahan 8174673441, Iran.
    Liu, Yuefei
    AlbaNova Univ Ctr, KTH Royal Inst Technol, Sch Engn Sci, Dept Appl Phys, SE-10691 Stockholm, Sweden..
    Bergman, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Delin, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. AlbaNova Univ Ctr, KTH Royal Inst Technol, Sch Engn Sci, Dept Appl Phys, SE-10691 Stockholm, Sweden.;KTH Royal Inst Technol, Swedish E Sci Res Ctr, SE-10044 Stockholm, Sweden..
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Örebro Univ, Sch Sci & Technol, SE-70182 Örebro, Sweden..
    Pereiro, Manuel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Thonig, Danny
    Örebro Univ, Sch Sci & Technol, SE-70182 Örebro, Sweden..
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Quantum Matter Theory.
    Magnon-magnon entanglement and its quantification via a microwave cavity2021In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 104, no 22, article id 224302Article in journal (Refereed)
    Abstract [en]

    Quantum magnonics is an emerging research field, with great potential for applications in magnon based hybrid systems and quantum information processing. Quantum correlation, such as entanglement, is a central resource in many quantum information protocols that naturally comes about in any study toward quantum technologies. This applies also to quantum magnonics. Here, we investigate antiferromagnetic coupling of two ferromagnetic sublattices that can have two different magnon modes. We show how this may lead to experimentally measurable bipartite continuous-variable magnon-magnon entanglement. The entanglement can be fully characterized via a single squeezing parameter or, equivalently, entanglement parameter. The clear relation between the entanglement parameter and the Einstein, Podolsky, and Rosen (EPR) function of the ground state opens up for experimental quantification magnon-magnon continuous-variable entanglement and EPR nonlocality. We propose a practical experimental realization to measure the EPR function of the ground state, in a setting that relies on magnon-photon interaction in a microwave cavity.

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  • 22.
    Aziz, Imran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Dahlbäck, R.
    Öjefors, E.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    High Gain Compact 57-66 GHz Antenna Array for Backhaul & Access Communications2018In: 12th European Conference on Antennas and Propagation (EuCAP 2018), 2018Conference paper (Refereed)
    Abstract [en]

    Highly integrated multilayered patch antenna arrays are proposed in this paper for 60 GHz wireless communications. Electromagnetic coupling between two stacked patches is used for improving the broadband performance. Three different structures of single column 4-element arrays are presented with center and corporate feeding networks. Maximum gain of 12.2 dBi and <-10 dB return loss in the entire unlicensed frequency band 57-66 GHz is measured. Furthermore, a compact 4×16 antenna array (41 mm x 13 mm) is presented with 18.7 dBi maximum gain, 8 GHz (5765) bandwidth and 7° HPBW (half power beam width) in H plane.

  • 23.
    Baba, Elbruz Murat
    et al.
    Inst Energy Technol, Dept Solar Energy, NO-2027 Kjeller, Norway.;Istanbul Tech Univ, Nanosci & Nano Engn Dept, TR-34469 Istanbul, Turkey..
    Montero, José Amenedo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Moldarev, Dmitrii
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Inst En MEPhI, Dept Mat Sci, Kashirskoe Shosse 31, Moscow 115409, Russia..
    Moro, Marcos V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Wolff, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Natl Res Nucl Univ MEPhI, Dept Mat Sci, Kashirskoe Shosse 31, Moscow 115409, Russia..
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sartori, Sabrina
    Univ Oslo, Dept Technol Syst, NO-2027 Kjeller, Norway..
    Zayim, Esra
    Istanbul Tech Univ, Nanosci & Nano Engn Dept, TR-34469 Istanbul, Turkey.;Istanbul Tech Univ, Fac Sci & Letters, Phys Engn Dept, TR-34469 Istanbul, Turkey..
    Karazhanov, Smagul
    Inst Energy Technol, Dept Solar Energy, NO-2027 Kjeller, Norway.;Natl Res Nucl Univ MEPhI, Dept Mat Sci, Kashirskoe Shosse 31, Moscow 115409, Russia..
    Preferential Orientation of Photochromic Gadolinium Oxyhydride Films2020In: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 25, no 14, article id 3181Article in journal (Refereed)
    Abstract [en]

    We report preferential orientation control in photochromic gadolinium oxyhydride (GdHO) thin films deposited by a two-step process. Gadolinium hydride (GdH2-x) films were grown by reactive magnetron sputtering, followed by oxidation in air. The preferential orientation, grain size, anion concentrations and photochromic response of the films were strongly dependent on the deposition pressure. The GdHO films showed a preferential orientation along the [100] direction and exhibited photochromism when synthesized at deposition pressures of up to 5.8 Pa. The photochromic contrast was larger than 20% when the films were deposited below 2.8 Pa with a 0.22 H-2/Ar flow ratio. We argue that the relation of preferential orientation and the post deposition oxidation since oxygen concentration is known to be a key parameter for photochromism in rare-earth oxyhydride thin films. The experimental observations described above were explained by the decrease of the grain size as a result of the increase of the deposition pressure of the sputtering gas, followed by a higher oxygen incorporation.

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  • 24.
    Baba, Elbruz Murat
    et al.
    Inst Energy Technol, Dept Solar Energy, N-2027 Kjeller, Norway;Istanbul Tech Univ, Nano Sci & Nano Engn Dept, TR-34469 Istanbul, Turkey.
    Montero, José Amenedo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Strugovshchikov, Evgenii
    Univ Tartu, Inst Phys, EE-50411 Tartu, Estonia.
    Zayim, Esra Ozkan
    Istanbul Tech Univ, Nano Sci & Nano Engn Dept, TR-34469 Istanbul, Turkey;Istanbul Tech Univ, Fac Sci & Letters, Dept Phys, TR-34469 Istanbul, Turkey.
    Karazhanov, Smagul
    Inst Energy Technol, Dept Solar Energy, N-2027 Kjeller, Norway.
    Light-induced breathing in photochromic yttrium oxyhydrides2020In: Physical Review Materials, E-ISSN 2475-9953, Vol. 4, no 2, article id 025201Article in journal (Refereed)
    Abstract [en]

    When exposed to air, metallic yttrium dihydride YH2 films turn into insulating and transparent yttrium oxyhydride (YHO). The incorporation of oxygen causes the lattice expansion of YH2 and the emergence of photochromic properties, i.e., YHO darkens reversibly when illuminated with light of adequate energy and intensity. However, the adequate bleaching of the photodarkened samples once the illumination has stopped is much faster in air than in inert atmosphere. According to this experimental evidence, the photochromic mechanism has to be related to an oxygen diffusion and exchange process. Since this process is accompanied by a lattice expansion/contraction, it can be said that YHO "breathes" when subjected to illumination/darkness cycling. Another interesting side effect of the breathing is the unexpected enhancement of the hydrophobicity of the YHO samples under illumination. A theoretical model able to explain the breathing in YHO is presented, together with the discussion of other alternative explanations.

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  • 25.
    Back, Markus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Out-of-plane Ferromagnetic Resonance (FMR) measurements on magnetic nanoparticle dispersions for biomedical sensor applications2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master work, we investigated the feasibility of a magnetic resonance measurement technique using magnetic nanoparticle dispersions in both liquid and solid form. The implementation is realised as a coplanar waveguide operating in the frequency range of 0.5 - 20 GHz and an electromagnet producing a static magnetic field of strength up to 1.2 T. The Gilbert magnetic damping factor is determined for polymer composites of magnetic nanoparticles and the gyromagnetic ratio is determined for both nanoparticle dispersions in liquid form and polymer composites.

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  • 26.
    Bae, Kichang
    et al.
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Shin, Dongmin
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Lee, Jonghun
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Kim, Seohan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Lee, Wookjin
    Pusan Natl Univ, Sch Mat Sci & Engn, Busan 46241, South Korea..
    Jo, Ilguk
    Dong Eui Univ, Adv Mat Engn, Busan 47340, South Korea..
    Lee, Junghoon
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Corrosion Resistance of Laser Powder Bed Fused AISI 316L Stainless Steel and Effect of Direct Annealing2022In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, no 18, article id 6336Article in journal (Refereed)
    Abstract [en]

    Alloy parts produced by an additive manufacturing method with rapid heat transfer from fast melting and solidification have different microstructures, characteristics, and performances compared with materials made by the conventional process. In this study, the corrosion and oxidation resistance of SS316L, which was prepared by the powder bed fusion process, was compared with those of cold-rolled SS316L. Additionally, the surface oxide film on stainless steel was thoroughly assessed since the film has the greatest influence on the corrosion and oxidation resistance. The effect of heat treatment on corrosion and oxidation resistance of SS316L fabricated by additive manufacturing was investigated. The SS316L has a microstructure formed by sub-grain cells, in which locally concentrated alloying elements form a stable passive film. As a result, it has a higher level of corrosion resistance and oxidation resistance than conventional cold-rolled materials. However, it was confirmed that the sub-grain cell was removed by heat treatment, which resulted in the degradation of corrosion and oxidation resistance.

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  • 27.
    Barwal, Vineet
    et al.
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Behera, Nilamani
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Husain, Sajid
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Gupta, Nanhe Kumar
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Hait, Soumyarup
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Pandey, Lalit
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Mishra, Vireshwar
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Chaudhary, Sujeet
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Spin gapless semiconducting behavior in inverse Heusler Mn2-xCo1 +/- xAl (0 x 1.75) thin films2021In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 518, article id 167404Article in journal (Refereed)
    Abstract [en]

    We correlate the structural, electrical, and magnetotransport properties of co-sputtered Mn2-xCo1?xAl full Heusler alloy thin films (0 x 1.75) in terms of Co/Mn concentration variation concerning the spin gapless semiconducting (SGS) behavior. The alloy thin films are found to stabilize in B2 order for near stoichiometric films, i.e. (x = 0 and x = 1), with the gradual change in the ordering and lattice parameter through Mn concentration variation. Magnetization measurements in Mn2-xCo1?xAl thin films reveal the ferromagnetic and ferrimagnetic character for x = 1.75, 1.5, 1.25 & 1, and x = 0, 0.5 & 0.75, respectively. The longitudinal resistivity measurement revealed that the films exhibit semiconducting behavior with a change in sign of the temperature coefficient of resistance with temperature. The anomalous Hall conductivity values for the Mn2-xCo1?xAl thin films are extracted from the Anomalous Hall effect (AHE) measurements. The non-saturating positive MR (linear in H) is being reported for the first time in the Mn2CoAl thin films. The value of the AHE coefficient and positive MR together serve as a piece of experimental evidence for the SGS character in the thin film. The SGS behavior becomes predominant at higher Mn concentration. Highly resistive thin films with ferromagnetic (ferrimagnetic) character in Co2MnAl (Mn2CoAl) could be beneficial for semiconductor spintronics, where we need a good resistive element to match up with Silicon base substrate.

  • 28.
    Barwal, Vineet
    et al.
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Gupta, Nanhe Kumar
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Hait, Soumyarup
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Husain, Sajid
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Behera, Nilamani
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Chaudhary, Sujeet
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Anisotropic Gilbert Damping in B2 ordered Full Heusler Alloy Co2MnAl thin films2020In: DAE Solid State Physics Symposium 2019 / [ed] Sharma, VK, Prajapat, CL & Yusuf, SM, 2020, article id 030574Conference paper (Refereed)
    Abstract [en]

    Structural and dynamic magnetization properties of Co2MnAl (CMA) full Heusler alloy thin films grown on Si (100) substrate at different substrate temperatures (Ts) 30°C, 200°C, 300°C, 400°C and 500°C are investigated. XRD patterns revealed the formation of B2 partially ordered phase at Ts=200°C and above. Ferromagnetic Resonance (FMR) technique have been used to determine the damping constant (α), resonance field (Hr) and line width (ΔH) of recorded spectra and fitted by using Landau-Lifshitz-Gilbert (LLG) equation. The lowest damping constant was found to be 0.007±0.002 for the film grown at Ts=200°C. Films exhibit uniaxial magnetic anisotropy. Anisotropic damping constant α is calculated along the easy and hard axis. Along the two directions remarkable change (almost ∼59%) in α is observed.

  • 29.
    Barwal, Vineet
    et al.
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Husain, Sajid
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Gupta, Nanhe Kumar
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Hait, Soumyarup
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Pandey, Lalit
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Chaudhary, Sujeet
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Structural and magneto-transport properties of co-sputtered MnAl thin films2020In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 503, article id 166654Article in journal (Refereed)
    Abstract [en]

    We report the structural and magneto-transport properties of co-sputtered MnAl alloy thin films grown on Si (1 0 0) at various substrate temperatures (T-s) ranging from room temperature to 500 degrees C. Analyses of the X-ray diffraction and DC-Magnetization data reveal that as the T-s of the films is changed, the volume fraction of ferromagnetic tau-MnxAl100-x (50 < x < 60) metastable phase retained in the films changes from 3.7 to 9.5% and the remaining fraction comprises of non-magnetic beta-MnAl and gamma(2)-phases. The temperature-dependent longitudinal resistivity variation demonstrates a semi-metallic nature in all these films. The temperature dependence of Hall Effect data further corroborates this semi-metallic behavior. The magnetoresistance (MR) response of these films is measured in the range of 10-300 K, both in the in-plane as well as out-of-plane magnetic field configurations. The out-of-plane MR is significantly larger than in-plane MR due to electron-hole compensation (which stems from mull-band effects) which is discussed further by plotting the Kohler's plot for the thin films.

  • 30.
    Basini, M.
    et al.
    Univ Milan, Dipartimento Fis, I-20133 Milan, Italy.;Univ Milan, INSTM, I-20133 Milan, Italy.;Stockholm Univ, Dept Phys, S-10691 Stockholm, Sweden..
    Sanna, S.
    Univ Bologna, Dept Phys & Astron A Righi, I-40127 Bologna, Italy..
    Orlando, T.
    Univ Pavia, Dipartimento Fis, Ist Nazl Fis Nucl, I-27100 Pavia, Italy.;Univ Pavia, INSTM, I-27100 Pavia, Italy.;Max Planck Inst Biophys Chem, D-37077 Gottingen, Germany..
    Bordonali, L.
    Karlsruhe Inst Technol, Inst Microstruct Technol, D-76344 Eggenstein Leopoldshafen, Germany..
    Cobianchi, M.
    Univ Pavia, Dipartimento Fis, Ist Nazl Fis Nucl, I-27100 Pavia, Italy.;Univ Pavia, INSTM, I-27100 Pavia, Italy..
    Arosio, P.
    Univ Milan, Dipartimento Fis, I-20133 Milan, Italy.;Univ Milan, INSTM, I-20133 Milan, Italy..
    Mariani, M.
    Univ Pavia, Dipartimento Fis, Ist Nazl Fis Nucl, I-27100 Pavia, Italy.;Univ Pavia, INSTM, I-27100 Pavia, Italy..
    Peddis, D.
    Univ Genoa, Dipartimento Chim & Chim Ind, I-16146 Genoa, Italy..
    Bonanni, V
    Univ Milan, Dipartimento Fis, I-20133 Milan, Italy.;Univ Milan, INSTM, I-20133 Milan, Italy.;CNR IOM, Area Sci Pk,Str Statale 14 Km 163-5, I-34149 Trieste, Italy..
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Kalaivani, T.
    Bilknet Univ UMRAM, Ankara, Turkey..
    Singh, G.
    Univ Sydney, Sch Biomed Engn, Sydney, NSW 2008, Australia..
    Larionova, J.
    Univ Montpellier, ENSCM, CNRS, ICGM, F-34095 Montpellier, France..
    Guari, Y.
    Univ Montpellier, ENSCM, CNRS, ICGM, F-34095 Montpellier, France..
    Lartigue, L.
    Univ Nantes, CNRS, CEISAM UMR 6230, F-44000 Nantes, France..
    Lascialfari, A.
    Univ Milan, Dipartimento Fis, I-20133 Milan, Italy.;Univ Milan, INSTM, I-20133 Milan, Italy.;Univ Pavia, Dipartimento Fis, Ist Nazl Fis Nucl, I-27100 Pavia, Italy.;Univ Pavia, INSTM, I-27100 Pavia, Italy..
    Low-temperature anomalies in muon spin relaxation of solid and hollow gamma-Fe2O3 nanoparticles: A pathway to detect unusual local spin dynamics2020In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 102, no 19, article id 195424Article in journal (Refereed)
    Abstract [en]

    By means of muon spin relaxation measurements we unraveled the temperature spin dynamics in monodisperse maghemite spherical nanoparticles with different surface to volume ratio, in two samples with a full core (diameter D similar to 4 and D similar to 5 nm) and one with a hollow core (external diameter D similar to 7.4 nm). The behavior of the muon longitudinal relaxation rates as a function of temperature allowed us to identify two distinct spin dynamics. The first is well witnessed by the presence of a characteristic peak for all the samples around the so-called muon blocking temperature T-B(mu+). A Bloembergen-Purcell-Pound (BPP)-like model reproduces the experimental data around the peak and at higher temperatures (20 < T < 100 K) by assuming the Neel reversal time of the magnetization as the dominating correlation time. An additional dynamic emerges in the samples with higher surface to volume ratio, namely, full 4 nm and hollow samples. This is witnessed by a shoulder of the main peak for T < 20 K at low longitudinal field (mu H-0 approximate to 15 mT), followed by an abrupt increase of the relaxation rate at T < 10 K, which is more evident for the hollow sample. These unusual anomalies of the longitudinal relaxation rate for T < T-B(mu+) are suggested to be due to the surface spins' dynamical behavior. Furthermore, for weak applied longitudinal magnetic field (mu H-0 approximate to 15 mT) and T < T-B(mu+) we observed damped coherent oscillations of the muon asymmetry, which are a signature of a quasistatic local field at the muon site as probed by muons implanted in the inner magnetic core of the nanoparticles. The muon spin relaxation technique turns out to be very successful to study the magnetic behavior of maghemite nanoparticles and to detect their unusual local spin dynamics in low magnetic field conditions.

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  • 31.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Atak, Gamze
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Hacettepe Univ, Phys Engn Dept, TR-06800 Ankara, Turkey..
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Electrochromic solar water splitting using a cathodic WO3 electrocatalyst2021In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 81, article id 105620Article in journal (Refereed)
    Abstract [en]

    Solar-driven water splitting is an emerging technology with high potential to generate fuel cleanly and sustainably. In this work, we show that WO3 can be used as a cathodic electrocatalyst in combination with (Ag,Cu) InGaSe2 solar cell modules to produce hydrogen and provide electrochromic functionality to water splitting devices. This electrochromic effect can be used to monitor the charge state or performance of the catalyst for process control or for controlling the temperature and absorbed heat due to tunable optical modulation of the electrocatalyst. WO3 films coated on Ni foam, using a wide range of different sputtering conditions, were investigated as cathodic electrocatalysts for the water splitting reaction. The solar-to-hydrogen (STH) efficiency of solar-driven water electrolysis was extracted using (Ag,Cu)InGaSe2 solar cell modules with a cell band gap varied in between 1.15 and 1.25 eV with WO3 on Ni foam-based electrolyzers and yielded up to 13% STH efficiency. Electrochromic properties during water electrolysis were characterized for the WO3 films on transparent substrate (indium tin oxide). Transmittance varied between 10% and 78% and the coloration efficiency at a wavelength of 528 nm and the overpotential of 400 mV was 40 cm(2) C-1. Hydrogen ion consumption in ion intercalation for electrochromic and hydrogen gas production for water electrolysis processes was discussed.

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  • 32.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Atak, Gamze
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Hacettepe University, Physics Engineering Department, 06800 Beytepe Ankara, Turkey.
    Stolt, Olof
    Solibro Research AB, Vallvägen 5, SE-75651 Uppsala, Sweden.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Stolt, Lars
    Solibro Research AB, Vallvägen 5, SE-75651 Uppsala, Sweden.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Bifunctional solar electrocatalytic water splitting using CIGS solar modules and WO3-based electrolyzers2019In: EMRS Spring Meeting 2019, 2019Conference paper (Refereed)
    Abstract [en]

    Using energy from the sun to produce a fuel and finally obtaining only water as an exhaust is a promising future technology for renewable energy and environmental sustainability. Solar driven water splitting is a method to produce hydrogen from solar energy. Coupling a solar cell with an electrolyzer is the approach with highest technological readiness. CuInxGa1-xSe2 (CIGS) is here a promising solar cell material for water splitting because it is possible to tune the band gap between 1.0 and 1.7 eV by changing the ratio between Ga and In, thus enabling maximum power point matching with an electrolyzer. Tungsten oxide is known as a photocatalytic material and mainly used for the oxygen evolution reaction in a water splitting process. However, WO3 films also show electrochromic activity together with hydrogen evolution. This result is interesting because it shows that WO3 films can be used as bifunctional materials for both hydrogen and oxygen evolution in water splitting, and provide additional functionalities to the system. In this study, WO3 films coated at different sputtering conditions on Ni foam and indium tin oxide substrates were investigated in the potential range of the hydrogen evolution reaction. The best overpotential of 164 mV vs. RHE at 10 mA/cm2 was obtained for WO3 films on Ni foam in 0.5 M H2SO4. The lowest potential needed for 10 mA/cm2 was measured 1.768 V for the electrolyzers consisting WO3 films on Ni foam as the cathode and non-coated Ni foam as the anode. Optimum solar-to-hydrogen (STH) efficiency of the CIGS solar cell modules and the electrolyzers was examined for different band gaps of the CIGS modules and sputtering conditions of WO3 films. Operation points of the combined system were calculated from the intersection of the voltage-current density curves for the CIGS modules and the electrolyzers. The results showed that the detailed sputtering conditions were not very critical to obtain high STH efficiency, indicating that the system could be robust and easily manufactured. The best-matched band gap of the CIGS was 1.19 eV and the highest STH efficiency of the CIGS driven WO3-based electrolyzers was 12.98 %.

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  • 33.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Malm, U.
    Solibro Res AB, Vallvagen 5, S-75651 Uppsala, Sweden..
    Neretnieks, P.
    Solibro Res AB, Vallvagen 5, S-75651 Uppsala, Sweden..
    Glüsen, A.
    Forschungszentrum Julich, Wilhelm Johnen Str, D-52428 Julich, Germany..
    Müller, M.
    Forschungszentrum Julich, Wilhelm Johnen Str, D-52428 Julich, Germany..
    Welter, K.
    Forschungszentrum Julich, Wilhelm Johnen Str, D-52428 Julich, Germany..
    Haas, S.
    Forschungszentrum Julich, Wilhelm Johnen Str, D-52428 Julich, Germany..
    Calnan, S.
    Helmholtz Zentrum Berlin Mat & Energie GmbH, PVcomB, Schwarzschildstr 3, D-12489 Berlin, Germany..
    Canino, A.
    ENEL Greenpower, Contrada Blocco Torrazze, I-95121 Catania, Italy..
    Milazzo, R. G.
    CNR, IMM, Ottava Str 5, I-95121 Catania, Italy..
    Privitera, S. M. S.
    CNR, IMM, Ottava Str 5, I-95121 Catania, Italy..
    Lombardo, S. A.
    CNR, IMM, Ottava Str 5, I-95121 Catania, Italy..
    Stolt, L.
    Solibro Res AB, Vallvagen 5, S-75651 Uppsala, Sweden..
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    The climatic response of thermally integrated photovoltaic-electrolysis water splitting using Si and CIGS combined with acidic and alkaline electrolysis2020In: Sustainable Energy & Fuels, E-ISSN 2398-4902, Vol. 4, no 12, p. 6011-6022Article in journal (Refereed)
    Abstract [en]

    The Horizon 2020 project PECSYS aims to build a large area demonstrator for hydrogen production from solar energy via integrated photovoltaic (PV) and electrolysis systems of different types. In this study, Si- and CIGS-based photovoltaics are developed together with three different electrolyzer systems for use in the corresponding integrated devices. The systems are experimentally evaluated and a general model is developed to investigate the hydrogen yield under real climatic conditions for various thin film and silicon PV technologies and electrolyser combinations. PV characteristics using a Si heterojunction (SHJ), thin film CuInxGa1-xSe2, crystalline Si with passivated emitter rear totally diffused and thin film Si are used together with temperature dependent catalyst load curves from both acidic and alkaline approaches. Electrolysis data were collected from (i) a Pt-IrO2-based acidic electrolysis system, and (ii) NiMoW-NiO-based and (iii) Pt-Ni foam-based alkaline electrolysis systems. The calculations were performed for mid-European climate data from Julich, Germany, which will be the installation site. The best systems show an electricity-to-hydrogen conversion efficiency of 74% and over 12% solar-to-hydrogen (STH) efficiencies using both acidic and alkaline approaches and are validated with a smaller lab scale prototype. The results show that the lower power delivered by all the PV technologies under low irradiation is balanced by the lower demand for overpotentials for all the electrolysis approaches at these currents, with more or less retained STH efficiency over the full year if the catalyst area is the same as the PV area for the alkaline approach. The total yield of hydrogen, however, follows the irradiance, where a yearly hydrogen production of over 35 kg can be achieved for a 10 m(2) integrated PV-electrolysis system for several of the PV and electrolyser combinations that also allow a significant (100-fold) reduction in necessary electrolyser area for the acidic approach. Measuring the catalyst systems under intermittent and ramping conditions with different temperatures, a 5% lowering of the yearly hydrogen yield is extracted for some of the catalyst systems while the Pt-Ni foam-based alkaline system showed unaffected or even slightly increased yearly yield under the same conditions.

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  • 34.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Oscarsson, Johan
    Solibro Res AB, Vallvägen 5, S-75651 Uppsala, Sweden.
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Stolt, Lars
    Solibro Res AB, Vallvägen 5, S-75651 Uppsala, Sweden.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    NiMoV and NiO-based catalysts for efficient solar-driven water splitting using thermally integrated photovoltaics in a scalable approach2021In: iScience, E-ISSN 2589-0042 , Vol. 24, no 1, article id 101910Article in journal (Refereed)
    Abstract [en]

    In this work, a trimetallic NiMoV catalyst is developed for the hydrogen evolution reaction and characterized with respect to structure, valence, and elemental distribution. The overpotential to drive a 10 mA cm−2 current density is lowered from 94 to 78 mV versus reversible hydrogen electrode by introducing V into NiMo. A scalable stand-alone system for solar-driven water splitting was examined for a laboratory-scale device with 1.6 cm2 photovoltaic (PV) module area to an up-scaled device with 100 cm2 area. The NiMoV cathodic catalyst is combined with a NiO anode in alkaline electrolyzer unit thermally connected to synthesized (Ag,Cu) (In,Ga)Se2 ((A)CIGS) PV modules. Performance of 3- and 4-cell interconnected PV modules, electrolyzer, and hydrogen production of the PV electrolyzer are examined between 25°C and 50°C. The PV-electrolysis device having a 4-cell (A)CIGS under 100 mW cm−2 illumination and NiMoV-NiO electrolyzer shows 9.1% maximum and 8.5% averaged efficiency for 100 h operation.

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  • 35.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Saguì, Nicole A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Oscarsson, Johan
    Solibro Res AB, Vallvagen 5, S-75651 Uppsala, Sweden.
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. KTH Royal Inst Technol, Dept Chem Engn, SE-10044 Stockholm, Sweden.
    Zwaygardt, Walter
    Forschungszentrum Julich, Inst Energy & Climate Res, IEK 14 Electrochem Proc Engn, D-52425 Julich, Germany.
    Lee, Minoh
    Forschungszentrum Julich, Inst Energy & Climate Res, IEK 14 Photovolta, D-52425 Julich, Germany.
    Mueller, Martin
    Forschungszentrum Juelich GmbH, Institute of Energy and Climate Research, IEK-14: Electrochemical Process Engineering, 52425 Juelich, Germany .
    Haas, Stefan
    Forschungszentrum Julich, Inst Energy & Climate Res, IEK 14 Photovolta, D-52425 Julich, Germany.
    Stolt, Lars
    Solibro Res AB, Vallvagen 5, S-75651 Uppsala, Sweden.
    Edoff, Marika
    Uppsala Univ, Solid State Elect, Dept Mat Sci & Engn, Box 534, S-75121 Uppsala, Sweden.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Scalable and thermally-integrated solar water-splitting modules using Ag-doped Cu(In,Ga)Se-2 and NiFe layered double hydroxide nanocatalysts2022In: Journal of Materials Chemistry A, ISSN 2050-7488, E-ISSN 2050-7496, Vol. 10, no 22, p. 12079-12091Article in journal (Refereed)
    Abstract [en]

    Photovoltaic (PV) electrolysis is an important and powerful technology for environmentally-friendly fuel production based on solar energy. By directly coupling solar cell materials to electrochemical systems to perform water electrolysis, solar energy can be converted into hydrogen fuel utilizing locally-generated heat and avoid losses from DC-DC convertors and power grid transmission. Although there have been significant contributions to the photoelectrochemical and PV-electrolysis field using isolated laboratory cells, the capacity to upscale and retain high levels of efficiency in larger modules remains a critical issue for widespread use and application. In this study, we develop thermally-integrated, solar-driven water-splitting device modules using AgCu(In,Ga)Se-2 (ACIGS) and an alkaline electrolyzer system with NiFe-layered double hydroxide (LDH) nanocatalysts with devices of 82-100 cm(2) area. The Ga-content in the ACIGS solar cells is tuned to achieve an optimal voltage for the catalyst system, and the average efficiencies and durability of the PV-electrolyzer were tested in up to seven-day indoor and 21 day outdoor operations. We achieved a solar-to-hydrogen (STH) module efficiency of 13.4% from gas volume measurements for the system with a six-cell CIGS-electrolyzer module with an active area of 82.3 cm(2) and a 17.27% PV module efficiency under 100 mW cm(-2) illumination, and thus 77% electricity-to-hydrogen efficiency at one full sun. Outdoor tests under mid-Europeen winter conditions exhibited an STH efficiency between 10 and 11% after the initial activation at the installation site in Julich, Germany, in December 2020, despite challenging outdoor-test weather conditions, including sub-zero temperatures.

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  • 36.
    Bellani, Sebastiano
    et al.
    BeDimens Spa, I-16163 Genoa, Italy.;Ist Italiano Tecnol, Graphene Labs, I-16163 Genoa, Italy..
    Najafi, Leyla
    BeDimens Spa, I-16163 Genoa, Italy.;Ist Italiano Tecnol, Graphene Labs, I-16163 Genoa, Italy..
    Prato, Mirko
    Ist Italiano Tecnol, Mat Characterizat Facil, I-16163 Genoa, Italy..
    Oropesa Nunez, Reinier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Martin-Garcia, Beatriz
    Ist Italiano Tecnol, Graphene Labs, I-16163 Genoa, Italy.;CIC NanoGUNE, Donostia San Sebastian 20018, Basque, Spain..
    Gagliani, Luca
    Ist Italiano Tecnol, Graphene Labs, I-16163 Genoa, Italy..
    Mantero, Elisa
    BeDimens Spa, I-16163 Genoa, Italy.;Ist Italiano Tecnol, Graphene Labs, I-16163 Genoa, Italy..
    Marasco, Luigi
    Ist Italiano Tecnol, Graphene Labs, I-16163 Genoa, Italy..
    Bianca, Gabriele
    Ist Italiano Tecnol, Graphene Labs, I-16163 Genoa, Italy.;Univ Genoa, Dipartimento Chim & Chim Ind, I-16146 Genoa, Italy..
    Zappia, Marilena, I
    BeDimens Spa, I-16163 Genoa, Italy.;Univ Calabria, Dept Phys, I-87036 Cosenza, Italy..
    Demirci, Cansunur
    Univ Genoa, Dipartimento Chim & Chim Ind, I-16146 Genoa, Italy.;Ist Italiano Tecnol, NanoChem, I-16163 Genoa, Italy..
    Olivotto, Silvia
    Enel Global Power Generat, Wind Technol Innovat, Rome, Italy..
    Mariucci, Giacomo
    Enel Green Power SpA, Storage & New Business Design Engn & Construct, Rome, Italy..
    Pellegrini, Vittorio
    BeDimens Spa, I-16163 Genoa, Italy.;Ist Italiano Tecnol, Graphene Labs, I-16163 Genoa, Italy..
    Schiavetti, Massimo
    Enel Global Power Generat, Thermal & Ind Innovat 40, Rome, Italy..
    Bonaccorso, Francesco
    BeDimens Spa, I-16163 Genoa, Italy.;Ist Italiano Tecnol, Graphene Labs, I-16163 Genoa, Italy..
    Graphene-Based Electrodes in a Vanadium Redox Flow Battery Produced by Rapid Low-Pressure Combined Gas Plasma Treatments2021In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 33, no 11, p. 4106-4121Article in journal (Refereed)
    Abstract [en]

    The development of high-power density vanadium redox flow batteries (VRFBs) with high energy efficiencies (EEs) is crucial for the widespread dissemination of this energy storage technology. In this work, we report the production of novel hierarchical carbonaceous nanomaterials for VRFB electrodes with high catalytic activity toward the vanadium redox reactions (VO2+/VO2+ and V2+/V3+). The electrode materials are produced through a rapid (minute timescale) low-pressure combined gas plasma treatment of graphite felts (GFs) in an inductively coupled radio frequency reactor. By systematically studying the effects of either pure gases (O-2 and N-2) or their combination at different gas plasma pressures, the electrodes are optimized to reduce their kinetic polarization for the VRFB redox reactions. To further enhance the catalytic surface area of the electrodes, single-/fewlayer graphene, produced by highly scalable wet-jet milling exfoliation of graphite, is incorporated into the GFs through an infiltration method in the presence of a polymeric binder. Depending on the thickness of the proton-exchange membrane (Nafion 115 or Nafion XL), our optimized VRFB configurations can efficiently operate within a wide range of charge/discharge current densities, exhibiting energy efficiencies up to 93.9%, 90.8%, 88.3%, 85.6%, 77.6%, and 69.5% at 25, 50, 75, 100, 200, and 300 mA cm(-2), respectively. Our technology is cost-competitive when compared to commercial ones (additional electrode costs < 100 (sic) m(-2)) and shows EEs rivalling the record-high values reported for efficient systems to date. Our work remarks on the importance to study modified plasma conditions or plasma methods alternative to those reported previously (e.g., atmospheric plasmas) to improve further the electrode performances of the current VRFB systems.

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  • 37.
    Belotcerkovtceva, Daria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Panda, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ramu, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Sarkar, Tapati
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Noumbe, Ulrich
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Kamalakar, M. Venkata
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    High current limits in chemical vapor deposited graphene spintronic devices2023In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 16, no 4, p. 4233-4239Article in journal (Refereed)
    Abstract [en]

    Understanding the stability and current-carrying capacity of graphene spintronic devices is key to their applications in graphene channel-based spin current sensors, spin-torque oscillators, and potential spin-integrated circuits. However, despite the demonstrated high current densities in exfoliated graphene, the current-carrying capacity of large-scale chemical vapor deposited (CVD) graphene is not established. Particularly, the grainy nature of chemical vapor deposited graphene and the presence of a tunnel barrier in CVD graphene spin devices pose questions about the stability of high current electrical spin injection. In this work, we observe that despite structural imperfections, CVD graphene sustains remarkably highest currents of 5.2 × 108 A/cm2, up to two orders higher than previously reported values in multilayer CVD graphene, with the capacity primarily dependent upon the sheet resistance of graphene. Furthermore, we notice a reversible regime, up to which CVD graphene can be operated without degradation with operating currents as high as 108 A/cm2, significantly high and durable over long time of operation with spin valve signals observed up to such high current densities. At the same time, the tunnel barrier resistance can be modified by the application of high currents. Our results demonstrate the robustness of large-scale CVD graphene and bring fresh insights for engineering and harnessing pure spin currents for innovative device applications. 

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  • 38.
    Bender, Philipp
    et al.
    Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, Munich, Germany..
    Wetterskog, Erik
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Vetenskapens Hus, Roslagstullsbacken 29, S-11421 Stockholm, Sweden..
    Salazar-Alvarez, German
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Uppsala Univ, Dept Mat Sci & Engn, Angstrom Lab, S-75103 Uppsala, Sweden.;Uppsala Univ, Ctr Neutron Scattering, S-75120 Uppsala, Sweden..
    Bergstrom, Lennart
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Hermann, Raphael P.
    Forschungszentrum Julich, JCNS 2, PGI 4, Julich, Germany.;Oak Ridge Natl Lab, Mat Sci & Technol Div, Oak Ridge, TN USA..
    Brueckel, Thomas
    Forschungszentrum Julich, JCNS 2, PGI 4, Julich, Germany..
    Wiedenmann, Albrecht
    Inst Laue Langevin, Grenoble, France..
    Disch, Sabrina
    Univ Cologne, Dept Chem, D-50935 Cologne, Germany..
    Shape-induced superstructure formation in concentrated ferrofluids under applied magnetic fields2022In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 55, no 6, p. 1613-1621Article in journal (Refereed)
    Abstract [en]

    The field-induced ordering of concentrated ferrofluids based on spherical and cuboidal maghemite nanoparticles is studied using small-angle neutron scattering, revealing a qualitative effect of the faceted shape on the interparticle interactions as shown in the structure factor and correlation lengths. Whereas a spatially disordered hard-sphere interaction potential with a short correlation length is found for similar to 9 nm spherical nanoparticles, nanocubes of a comparable particle size exhibit a more pronounced interparticle interaction and the formation of linear arrangements. Analysis of the anisotropic two-dimensional pair distance correlation function gives insight into the real-space arrangement of the nanoparticles. On the basis of the short interparticle distances found here, oriented attachment, i.e. a face-to-face arrangement of the nanocubes, is likely. The unusual field dependence of the interparticle correlations suggests a field-induced structural rearrangement.

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  • 39. Benesperi, Iacopo
    et al.
    Michaels, Hannes
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Pavone, Michele
    Probert, Michael R.
    Waddell, Paul
    Muñoz-García, Ana Belén
    Freitag, Marina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Dynamic dimer copper coordination redox shuttles2022In: Chem, ISSN 2451-9308, E-ISSN 2451-9294, Vol. 8, no 2, p. 439-449Article in journal (Refereed)
    Abstract [en]

    Summary Conventional redox mediators based on metal coordination complexes undergo electron transfer through the change in oxidation state of the metal center. However, electron transfer kinetics are offset toward preferred oxidation states when preorganized ligands constrain the reorganization of the coordination sphere. In contrast, we report here on dimeric copper(II/I) redox couples, wherein the extent of oxidation/reduction of two metal centers dictates the dynamic formation of dimer and monomer complexes: the dimeric (Cu(I))2 transitions to monomers of Cu(II). The bis(thiazole/pyrrole)-bipyridine tetradentate ligands stabilize both oxidation states of the unique redox systems. The dynamic dimer redox mediators offer a viable two-electron redox mechanism to develop efficient hybrid solar cells through inhibited recombination and rapid charge transport. Density functional theory calculations reveal inner reorganization energies for single-electron transfer as low as 0.27 eV, marking the dimeric complexes superior redox systems over single complexes as liquid and potentially solid-state electrolytes.

  • 40.
    Bengtsson, F.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Pehlivan, I. Bayrak
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Karlsson, S.
    RISE Res Inst Sweden, Dept Bldg & Real Estate, Built Environm Div, RISE Glass unit, Vejdes plats 3, SE-35252 Växjö, Sweden..
    Alkali ion diffusion and structure of chemically strengthened TiO2 doped soda-lime silicate glass2022In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 586, article id 121564Article in journal (Refereed)
    Abstract [en]

    Diffusion kinetics and structural properties of chemically strengthened titania-doped soda-lime silicate glasses were studied by depth-resolved X-ray photoelectron spectroscopy, Raman spectroscopy and spectrophotometry. The glasses were ion exchanged, whereby Na+ in the glass was replaced by K+ in a molten salt bath, at four different treatment temperatures between 350 and 500 ?. The alkali diffusion coefficient, DK-Na, and corresponding activation energy were calculated to be between 3.26x10(-12) and 4.47x10 & nbsp;(-11) cm(2)s(-1) and between 101.1 kJmol(-1) and 105.6 kJmol(-1), respectively. DK-Na was observed to decrease as the TiO2 concentration was increased. Raman analysis showed Q3-silicate species with different bond lengths, which was attributed to surface compressive stresses, and increasing Si-O-Si bond angle with increasing ion exchange temperature. Ti3+ ions exist as a minor species in the glasses and its concentration depends on the TiO2 content. Deconvolution of the optical absorption spectra reveals Jahn-Teller compressive distortion of the Ti3+ octahedral coordination.

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  • 41.
    Bengtsson, Felix
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Depth-resolved Raman Spectroscopy and X-ray Photoelectron Spectroscopy to Evaluate the Structural and Chemical Properties of Chemically Strenghtened Glasses2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, the structural and chemical properties of a series of titanosilicate glasseswere investigated. The glasses were subjected to a chemical strengthening process(with K^+ replacing Na^+) at four different treatment temperatures and studied withXPS- and Raman spectroscopy. From the XPS analysis, the interdiffusion coefficientsand activation energies were calculated to be between 3.9*10^-12–4.3*10^-11 cm^2/sand 101.1-103.6 kJ/mol respectively. An increase in the TiO2 content lead to adecrease in the interdiffusion coefficients and consequently to an increase in theactivation energies. From the Raman analysis, the presence of compressive stressescould be observed as well as an indication of viscous relaxation from the Raman shifts.An attempt to model the compressive stresses as a function of depth was alsoperformed using a modified version of a stress evaluation method proposed byTerakado, Nobuaki, et al. "A novel method for stress evaluation in chemicallystrengthened glass based on micro-Raman spectroscopy." Communications Physics3.1 (2020): 1-7. The calculated values of the compressive stresses were found to bereasonable for the measurements that followed the requirements of the method, butas this modified version is based on assumptions, no direct conclusions could bedrawn regarding its validity.

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  • 42.
    Beydaghi, Hossein
    et al.
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy.;BeDimens SpA, Via Lungotorrente Secca 30R, I-16163 Genoa, Italy..
    Bellani, Sebastiano
    BeDimens SpA, Via Lungotorrente Secca 30R, I-16163 Genoa, Italy..
    Najafi, Leyla
    BeDimens SpA, Via Lungotorrente Secca 30R, I-16163 Genoa, Italy..
    Oropesa-Nuñez, Reinier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Bianca, Gabriele
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy.;Univ Genoa, Dipartimento Chim & Chim Ind, Via Dodecaneso 31, I-16146 Genoa, Italy..
    Bagheri, Ahmad
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy..
    Conticello, Irene
    BeDimens SpA, Via Lungotorrente Secca 30R, I-16163 Genoa, Italy..
    Martin-Garcia, Beatriz
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy..
    Kashefi, Sepideh
    Semnan Univ, Dept Chem Engn, Semnan 3513119111, Iran..
    Serri, Michele
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy..
    Liao, Liping
    Univ Chem & Technol Prague, Dept Inorgan Chem, Tech 5, Prague 16628 6, Czech Republic..
    Sofer, Zdenek
    Univ Chem & Technol Prague, Dept Inorgan Chem, Tech 5, Prague 16628 6, Czech Republic..
    Pellegrini, Vittorio
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy.;BeDimens SpA, Via Lungotorrente Secca 30R, I-16163 Genoa, Italy..
    Bonaccorso, Francesco
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy.;BeDimens SpA, Via Lungotorrente Secca 30R, I-16163 Genoa, Italy..
    Sulfonated NbS2-based proton-exchange membranes for vanadium redox flow batteries2022In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 14, no 16, p. 6152-6161Article in journal (Refereed)
    Abstract [en]

    In this work, novel proton-exchange membranes (PEMs) based on sulfonated poly(ether ether ketone) (SPEEK) and two-dimensional (2D) sulfonated niobium disulphide (S-NbS2) nanoflakes are synthesized by a solution-casting method and used in vanadium redox flow batteries (VRFBs). The NbS2 nanoflakes are produced by liquid-phase exfoliation of their bulk counterpart and chemically functionalized with terminal sulfonate groups to improve dimensional and chemical stabilities, proton conductivity (sigma) and fuel barrier properties of the as-produced membranes. The addition of S-NbS2 nanoflakes to SPEEK decreases the vanadium ion permeability from 5.42 x 10(-7) to 2.34 x 10(-7) cm(2) min(-1). Meanwhile, it increases the membrane sigma and selectivity up to 94.35 mS cm(-2) and 40.32 x 10(4) S min cm(-3), respectively. The cell assembled with the optimized membrane incorporating 2.5 wt% of S-NbS2 nanoflakes (SPEEK:2.5% S-NbS2) exhibits high efficiency metrics, i.e., coulombic efficiency between 98.7 and 99.0%, voltage efficiency between 90.2 and 73.2% and energy efficiency between 89.3 and 72.8% within the current density range of 100-300 mA cm(-2), delivering a maximum power density of 0.83 W cm(-2) at a current density of 870 mA cm(-2). The SPEEK:2.5% S-NbS2 membrane-based VRFBs show a stable behavior over 200 cycles at 200 mA cm(-2). This study opens up an effective avenue for the production of advanced SPEEK-based membranes for VRFBs.

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  • 43.
    Beydaghi, Hossein
    et al.
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy..
    Najafi, Leyla
    BeDimensional SpA, Via Albisola 121, I-16163 Genoa, Italy..
    Bellani, Sebastiano
    BeDimensional SpA, Via Albisola 121, I-16163 Genoa, Italy..
    Bagheri, Ahmad
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy..
    Martin-Garcia, Beatriz
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy..
    Salarizadeh, Parisa
    Vali E Asr Univ Rafsanjan, High Temp Fuel Cell Res Dept, Rafsanjan 7718897111, Iran..
    Hooshyari, Khadijeh
    Urmia Univ, Fac Chem, Dept Appl Chem, Orumiyeh 5756151818, Iran..
    Naderizadeh, Sara
    Ist Italiano Tecnol, Smart Mat, Via Morego 30, I-16163 Genoa, Italy..
    Serri, Michele
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy..
    Pasquale, Lea
    Ist Italiano Tecnol, Mat Characterizat Facil, Via Morego 30, I-16163 Genoa, Italy..
    Wu, Bing
    Univ Chem & Technol Prague, Dept Inorgan Chem, Tech 5, Prague 16628 6, Czech Republic..
    Oropesa Nunez, Reinier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sofer, Zdenek
    Univ Chem & Technol Prague, Dept Inorgan Chem, Tech 5, Prague 16628 6, Czech Republic..
    Pellegrini, Vittorio
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy.;BeDimensional SpA, Via Albisola 121, I-16163 Genoa, Italy..
    Bonaccorso, Francesco
    Ist Italiano Tecnol, Graphene Labs, Via Morego 30, I-16163 Genoa, Italy.;BeDimensional SpA, Via Albisola 121, I-16163 Genoa, Italy..
    Functionalized metallic transition metal dichalcogenide (TaS2) for nanocomposite membranes in direct methanol fuel cells2021In: Journal of Materials Chemistry A, ISSN 2050-7488, E-ISSN 2050-7496, Vol. 9, no 10, p. 6368-6381Article in journal (Refereed)
    Abstract [en]

    In this work, we designed a novel nanocomposite proton-exchange membrane (PEM) based on sulfonated poly(ether ether ketone) (SPEEK) and tantalum disulfide functionalized with terminal sulfonate groups (S-TaS2). The PEMs are prepared through a solution-casting method and exploited in direct methanol fuel cells (DMFCs). Two-dimensional S-TaS2 nanoflakes were prepared as a functional additive to produce the novel nanocomposite membrane for DMFCs due to their potential as a fuel barrier and an excellent proton conductor. To optimize the degree of sulfonation (DS) of SPEEK and the weight percentage (wt%) of S-TaS2 nanoflakes in PEMs, we used the central composite design of the response surface method. The optimum PEM was obtained for SPEEK DS of 1.9% and a weight fraction (wt%) of S-TaS2 nanoflakes of 70.2%. The optimized membrane shows a water uptake of 45.72%, a membrane swelling of 9.64%, a proton conductivity of 96.24 mS cm(-1), a methanol permeability of 2.66 x 10(-7) cm(2) s(-1), and a selectivity of 36.18 x 10(4) S s cm(-3). Moreover, SPEEK/S-TaS2 membranes show superior thermal and chemical stabilities compared to those of pristine SPEEK. The DMFC fabricated with the SPEEK/S-TaS2 membrane has reached the maximum power densities of 64.55 mW cm(-2) and 161.18 mW cm(-2) at 30 degrees C and 80 degrees C, respectively, which are similar to 78% higher than the values obtained with the pristine SPEEK membrane. Our results demonstrate that SPEEK/S-TaS2 membranes have a great potential for DMFC applications.

  • 44.
    Bouchikhi, Benachir
    et al.
    Moulay Ismail Univ Meknes, Fac Sci, Dept Phys, Sensor Elect & Instrumentat Grp, BP 11201, Zitoune 11201, Meknes, Morocco..
    Chludzinski, Tomasz
    Gdansk Univ Technol, Fac Elect Telecommun & Informat, Gdansk, Poland..
    Saidi, Tarik
    Moulay Ismail Univ Meknes, Fac Sci, Dept Phys, Sensor Elect & Instrumentat Grp, BP 11201, Zitoune 11201, Meknes, Morocco..
    Smulko, Janusz
    Gdansk Univ Technol, Fac Elect Telecommun & Informat, Gdansk, Poland..
    El Bari, Nezha
    Moulay Ismail Univ Meknes, Fac Sci, Dept Biol, Biotechnol Agroalimentary & Biomed Anal Grp, BP 11201, Zitoune 11201, Meknes, Morocco..
    Wen, He
    Hunan Univ, Coll Elect & Informat Engn, Changsha, Peoples R China..
    Ionescu, Radu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Formaldehyde detection with chemical gas sensors based on WO3 nanowires decorated with metal nanoparticles under dark conditions and UV light irradiation2020In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 320, article id 128331Article in journal (Refereed)
    Abstract [en]

    We report results of formaldehyde gas (CH2O) detection under dark conditions and UV light irradiation with pristine tungsten trioxide nanowires (WO3 NWs) and metal nanoparticles decorated WO3 NWs gas sensing layers. The resistive layers were deposited by one step aerosol assisted chemical vapor deposition (AACVD) on commercial alumina substrates with 10-pair interdigitated platinum electrodes. The elaborated gas sensors, based on pristine WO3 and on WO3 decorated with Au, Pt, Au/Pt, Ni and Fe nanoparticles, were investigated towards three concentrations of formaldehyde gas (5, 10 and 15 ppm) under dark conditions and under UV light irradiation at the wavelength of 394 nm. Two main effects were observed: firstly, under UV light irradiation the response time for CH2O desorption was significantly reduced with the exception of the nanomaterial with Fe NPs dopant; secondly, the gas induced baseline shift was reduced under UV light irradiation conditions. These results can be explained by the additional energy induced by the UV light, accelerating the adsorption-desorption processes. The results obtained confirmed that both the decoration of WO3 NWs with selected metal nano particles as well as sensors operation under UV light irradiation are a practical and affordable way to enhance gas sensing towards formaldehyde detection, although both strategies applied together did not introduce an amplified synergetic effect.

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  • 45.
    Brebu, M.
    et al.
    Petru Poni Inst Macromol Chem, Iasi, Romania..
    Beleno, K.
    Petru Poni Inst Macromol Chem, Iasi, Romania.;Univ Pamplona, Pamplona, Colombia..
    Ionescu, Radu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Turcu, D.
    Spiru Haret Univ, Fac Vet Med, Bucharest, Romania..
    Dinu, H.
    Pasteur Inst, Bucharest, Romania..
    Caciandone, H.
    CSV Targusor, Constanta, Romania..
    Enache, A. A.
    Apel Laser, Mogosoaia, Ilfov, Romania..
    Volatolomic analysis applied to farm animals. II.: Volatile compounds emitted from the faeces of cattle2020In: REVISTA ROMANA DE MEDICINA VETERINARA, ISSN 1220-3173, Vol. 30, no 1, p. 34-38Article in journal (Refereed)
    Abstract [en]

    Volatolomics opens new possibilities for the study of the biological systems. The volatility distribution of highly- and semi-volatile organic compounds released from the faeces of cattle was studied. Samples were collected from farm animals in three regions of Romania, namely Ramnicu Valcea, Bistri.a Nasaud and Constanta. Special procedures for sample collection, storage, transportation and analysis were developed. Organic compounds were found in a broad boiling point range, from n-C-6 (36 degrees C) up to n-C-17 (302 degrees C), but the highest concentration of about 80 % was found in the range of n-C-9-n-C-12 (151-216 degrees C), with a peak at n-C-10 (151-174 degrees C). Only slight variations were observed among the samples collected from different geographical regions.

  • 46.
    Brebu, M.
    et al.
    Petru Poni Inst Macromol Chem, Iasi, Jud Iasi, Romania..
    Mogollon, Lisset
    Univ Pamplona, Pamplona, Colombia..
    Ionescu, Radu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Turcu, D.
    Spiru Haret Univ, Fac Vet Med, Bucharest, Romania..
    Grigorescu, P.
    Spiru Haret Univ, Fac Vet Med, Bucharest, Romania..
    Iordache, A.
    CSV Tetoiu, Jud Valcea, Romania..
    Enache, A. A.
    Apel Laser, Mogosoaia, Jud Ilfov, Romania..
    Volatolomic analysis applied to farm animals. III.: Volatile compounds emitted through skin of cattle2020In: REVISTA ROMANA DE MEDICINA VETERINARA, ISSN 1220-3173, Vol. 30, no 2, p. 29-32Article in journal (Refereed)
    Abstract [en]

    Volatolomics opens new possibilities for the study of biological systems. Volatility distribution of highly-and semi-volatile organic compounds emitted through the skin of cattle was studied. Samples were collected from farm animals in three regions of Romania, namely Ramnicu Valcea, Bistrita Nasaud and Constanta. Special procedures for sample collection, storage, transportation and analysis were developed. About 62 -68 % of organic compounds emitted through skin had the volatility in the boiling point range of n-C(10 )ormal paraffin (151-174 degrees C) and another 16-18 % was in the range of n-C-11- n-C-12 (174-216 degrees C). Only slight variations were observed among samples collected from different geographical regions.

  • 47.
    Brebu, Mihai
    et al.
    Petru Poni Inst Macromol Chem, Aleea Grigore Gh Voda 41A, Iasi 700487, Romania..
    Simion, Violeta Elena
    Spiru Haret Univ, Fac Vet Med, Bd Basarabia 256, Bucharest 030171, Romania..
    Andronie, Viorel
    Spiru Haret Univ, Fac Vet Med, Bd Basarabia 256, Bucharest 030171, Romania..
    Jaimes-Mogollon, Aylen Lisset
    Univ Pamplona, Fac Engn & Architecture, GISM Grp, Via Bucaramanga Km 1, Pamplona 543050, Colombia..
    Beleno-Saenz, Kelvin de Jesus
    Univ Pamplona, Fac Engn & Architecture, GISM Grp, Via Bucaramanga Km 1, Pamplona 543050, Colombia.;Univ Autonoma Caribe, Dept Mechatron Engn, Calle 90 46-112, Barranquilla 080020, Colombia..
    Ionescu, Florina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Welearegay, Tesfalem
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Suschinel, Raluca
    Estonian Univ Life Sci, Inst Vet Med & Anim Sci, Kreutzwaldi 62, EE-51006 Tartu, Estonia..
    de Lema, Jose Bruno
    Estonian Univ Life Sci, Inst Vet Med & Anim Sci, Kreutzwaldi 62, EE-51006 Tartu, Estonia.;D Asociat, Paseo Montana 14, Granollers 08402, Barcelona, Spain..
    Ionescu, Radu
    D Asociat, Paseo Montana 14, Granollers 08402, Barcelona, Spain..
    Putative volatile biomarkers of bovine tuberculosis infection in breath, skin and feces of cattle2023In: Molecular and Cellular Biochemistry, ISSN 0300-8177, E-ISSN 1573-4919, Vol. 478, no 11, p. 2473-2480Article in journal (Refereed)
    Abstract [en]

    Bovine tuberculosis (bTB) is an infectious disease with significant impact on animal health, public health and international trade. Standard bTB screening in live cattle consists in injecting tuberculin and measuring the swelling at the place of injection few days later. This procedure is expensive, time-consuming, logistically challenging, and is not conclusive before performing confirmatory tests and additional analysis. The analysis of the volatile organic compounds (VOCs) emitted by non-invasive biological samples can provide an alternative diagnostic approach suitable for bTB screening. In the present study, we analyzed VOC samples emitted through the breath, feces and skin of 18 cows diagnosed with bTB from three farms from Romania, as well as of 27 negative cows for bTB from the same farms. Analytical studies employing gas chromatography coupled to mass spectrometry revealed 80 VOCs emitted through the breath, 200 VOCs released by feces, and 80 VOCs emitted through the skin. Statistical analysis of these compounds allowed the identification of 3 tentative breath VOC biomarkers (acetone; 4-methyldecane; D-limonene), 9 tentative feces VOC biomarkers (toluene; [(1,1-dimethylethyl)thio]acetic acid; alpha-thujene; camphene; phenol; o-cymene; 3-(1,1-dimethylethyl)-2,2,4,4-tetramethyl-3-pentanol; 2,5-dimethylhexane-2,5-dihydroperoxide; 2,4-di-tert-butylphenol), and 3 tentative skin VOC biomarkers (ammonia; 1-methoxy-2-propanol; toluene). The possible pathway of these volatile biomarkers is discussed.

  • 48.
    Breijaert, T. C.
    et al.
    Swedish Univ Agr Sci, Dept Mol Sci Bioctr, Almas 5, SE-756 51 Uppsala, Sweden.
    Daniel, G.
    Swedish Univ Agr Sci, Dept Forest Biomat & Technol Wood Sci, Vallvagen 9C-D, S-756 51 Uppsala, Sweden.
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Kessler, V. G.
    Swedish Univ Agr Sci, Dept Mol Sci Bioctr, Almas 5, SE-756 51 Uppsala, Sweden.
    Granberg, H.
    Res Inst Sweden RISE, Dept Mat & Surface Design Smart Mat, Drottning Kristinas vag 61, S-114 28 Stockholm, Sweden.
    Hakansson, K.
    Res Inst Sweden RISE, Dept Mat & Surface Design Smart Mat, Drottning Kristinas vag 61, S-114 28 Stockholm, Sweden.
    Seisenbaeva, G. A.
    Swedish Univ Agr Sci, Dept Mol Sci Bioctr, Almas 5, SE-756 51 Uppsala, Sweden.
    Self-assembly of ferria-nanocellulose composite fibres2022In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 291, article id 119560Article in journal (Refereed)
    Abstract [en]

    An environmentally benign synthesis of a magnetically responsive carboxymethylated cellulose nanofibril-based material is reported. Applied experimental conditions lead to the in-situ formation of magnetite nanoparticles with primary particle sizes of 2.0-4.0 nm or secondary particles of 3.6-16.4 nm depending on whether nucleation occurred between individual carboxymethylated cellulose nanofibrils, or on exposed fibril surfaces. The increase in magnetite particle size on the cellulose fibril surfaces was attributed to Ostwald ripening, while the small particles formed within the carboxymethyl cellulose aggregates were presumably due to steric interactions. The magnetite nanoparticles were capable of coordinating to carboxymethylated cellulose nanofibrils to form large "fibre-like" assemblies. The confinement of small particles within aggregates of reductive cellulose molecules was most likely responsible for excellent conservation of magnetic characteristics on storage of this material. The possibility for using the material in drug delivery applications with release rate controlled by daylight illumination is presented.

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  • 49.
    Calnan, Sonya
    et al.
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Bagacki, Rory
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Bao, Fuxi
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Dorbandt, Iris
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Kemppainen, Erno
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Schary, Christian
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Schlatmann, Rutger
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Leonardi, Marco
    IMM -Institute for microelectronics and microsystems Consiglio Nazionale Delle Ricerche CNR-IMM Zona Industriale Ottava Strada, 5 95121 Catania Italy.
    Lombardo, Salvatore A.
    IMM -Institute for microelectronics and microsystems Consiglio Nazionale Delle Ricerche CNR-IMM Zona Industriale Ottava Strada, 5 95121 Catania Italy.
    Milazzo, R. Gabriella
    IMM -Institute for microelectronics and microsystems Consiglio Nazionale Delle Ricerche CNR-IMM Zona Industriale Ottava Strada, 5 95121 Catania Italy.
    Privitera, Stefania M. S.
    IMM -Institute for microelectronics and microsystems Consiglio Nazionale Delle Ricerche CNR-IMM Zona Industriale Ottava Strada, 5 95121 Catania Italy.
    Bizzarri, Fabrizio
    Enel Green Power SpA Viale Regina Margherita, 125 00198 Roma Italy.
    Connelli, Carmelo
    Enel Green Power SpA Viale Regina Margherita, 125 00198 Roma Italy.
    Consoli, Daniele
    Enel Green Power SpA Viale Regina Margherita, 125 00198 Roma Italy.
    Gerardi, Cosimo
    Enel Green Power SpA Viale Regina Margherita, 125 00198 Roma Italy.
    Zani, Pierenrico
    Enel Green Power SpA Viale Regina Margherita, 125 00198 Roma Italy.
    Carmo, Marcelo
    Institute of Energy and Climate Research 14 Electrochemical Process Engineering (IEK-14) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Str. 52428 Jülich Germany.
    Haas, Stefan
    Institute of Energy and Climate Research 5 Photovoltaics (IEK-5) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Str. 52428 Jülich Germany.
    Lee, Minoh
    Institute of Energy and Climate Research 5 Photovoltaics (IEK-5) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Str. 52428 Jülich Germany.
    Mueller, Martin
    Institute of Energy and Climate Research 14 Electrochemical Process Engineering (IEK-14) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Str. 52428 Jülich Germany.
    Zwaygardt, Walter
    Institute of Energy and Climate Research 14 Electrochemical Process Engineering (IEK-14) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Str. 52428 Jülich Germany.
    Oscarsson, Johan
    Solibro Research AB Vallvägen 5 75651 Uppsala Sweden.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology. Solibro Research AB Vallvägen 5 75651 Uppsala Sweden.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Development of Various Photovoltaic‐Driven Water Electrolysis Technologies for Green Solar Hydrogen Generation2021In: Solar RRL, E-ISSN 2367-198X, Vol. 6, no 5, article id 2100479Article in journal (Refereed)
    Abstract [en]

    Direct solar hydrogen generation via a combination of photovoltaics (PV) and water electrolysis can potentially ensure a sustainable energy supply while minimizing greenhouse emissions. The PECSYS project aims at demonstrating asolar-driven electrochemical hydrogen generation system with an area >10 m2 with high efficiency and at reasonable cost. Thermally integrated PV electrolyzers(ECs) using thin-film silicon, undoped, and silver-doped Cu(In,Ga)Se2 and silicon heterojunction PV combined with alkaline electrolysis to form one unit are developed on a prototype level with solar collection areas in the range from 64 to2600 cm2 with the solar-to-hydrogen (StH) efficiency ranging from 4 to 13%. Electrical direct coupling of PV modules to a proton exchange membrane EC test the effects of bifacially (730 cm2 solar collection area) and to study the long-term operation under outdoor conditions (10 m2 collection area) is also investigated. In both cases, StH efficiencies exceeding 10% can be maintained over the test periods used. All the StH efficiencies reported are based on measured gas outflow using mass flow meters.

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  • 50.
    Cedervall, Johan
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.;Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Facil, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Clulow, Rebecca
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Boström, Hanna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Max Planck Inst Solid State Res, Heisenbergsstr 1, D-70569 Stuttgart, Germany..
    Joshi, Deep C.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Andersson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden..
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Beran, Premysl
    Acad Sci Czech Republ, Nucl Phys Inst, Rez 25068, Czech Republic.;European Spallat Source ESS ERIC, Box 176, S-22100 Lund, Sweden..
    Smith, Ronald, I
    Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Facil, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Tseng, Jo-Chi
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Berastegui, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Shafeie, Samrand
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden..
    Phase stability and structural transitions in compositionally complex LnMO(3) perovskites2021In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 300, article id 122213Article in journal (Refereed)
    Abstract [en]

    Entropy stabilised materials have possibilities for tailoring functionalities to overcome challenges in materials science. The concept of configurational entropy can also be applied to metal oxides, but it is unclear whether these could be considered as solid solutions in the case of perovskite-structured oxides and if the configurational entropy plays a stabilising role. In this study, compositionally complex perovskite oxides, LnMO(3) (Ln = La, Nd, Sm, Ca and Sr, M = Ti, Cr, Mn, Fe, Co, Ni, and Cu), are investigated for their phase stability and magnetic behaviour. Phase-pure samples were synthesised, and the room temperature structures were found to crystallise in either Pnma or R (3) over barc space groups, depending on the composition and the resulting tolerance factor, while the structural transition temperatures correlate with the pseudo cubic unit cell volume. The techniques used included diffraction with X-rays and neutrons, both ex- and in-situ, X-ray photoelectron spectroscopy, magnetometry as well as electron microscopy. Neutron diffraction studies on one sample reveal that no oxygen vacancies are found in the structure and that the magnetic properties are ferrimagnetic-like with magnetic moments mainly coupled antiferromagnetically along the crystallographic c-direction. X-ray photoelectron spectroscopy gave indications of the oxidation states of the constituting ions where several mixed oxidation states are observed in these valence-compensated perovskites.

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