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  • 1.
    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.

  • 2.
    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.

  • 3.
    Almquist, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Mattsson, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    High-fidelity numerical solution of the time-dependent Dirac equation2014In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 262, p. 86-103Article in journal (Refereed)
  • 4.
    Almquist, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Mattsson, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Stable and accurate simulation of phenomena in relativistic quantum mechanics2013In: Proc. 11th International Conference on Mathematical and Numerical Aspects of Waves, Tunisia: ENIT , 2013, p. 213-214Conference paper (Other academic)
  • 5.
    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)
  • 6.
    Amft, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Skorodumova, Natalia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Thermally Excited Vibrations in Copper, Silver, and Gold Trimers and Enhanced Binding of COManuscript (preprint) (Other academic)
  • 7.
    Anaraki, Elham Halvani
    et al.
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland;Isfahan Univ Technol, Dept Mat Engn, Esfahan 8415683111, Iran.
    Kermanpur, Ahmad
    Isfahan Univ Technol, Dept Mat Engn, Esfahan 8415683111, Iran.
    Mayer, Matthew T.
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland;Helmholtz Zentrum Berlin, Young Investigator Grp Electrochem Convers CO2, Hahn Meitner Pl 1, D-14109 Berlin, Germany.
    Steier, Ludmilla
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland;Imperial Coll London, Dept Chem, London SW7 2AZ, England.
    Ahmed, Taha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Turren-Cruz, Silver-Hamill
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland.
    Seo, Jiyoun
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.
    Luo, Jingshan
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.
    Zakeeruddin, Shaik Mohammad
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland;Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.
    Tress, Wolfgang Richard
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland;Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Graetzel, Michael
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland.
    Correa-Baena, Juan-Pablo
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland;MIT, Dept Mech Engn, 77 Massachusetts Ave, Cambridge, MA 02139 USA.
    Low-Temperature Nb-Doped SnO2 Electron-Selective Contact Yields over 20% Efficiency in Planar Perovskite Solar Cells2018In: ACS Energy Letters, E-ISSN 2380-8195, Vol. 3, no 4, p. 773-778Article in journal (Refereed)
    Abstract [en]

    Low-temperature planar organic inorganic lead halide perovskite solar cells have been at the center of attraction as power conversion efficiencies go beyond 20%. Here, we investigate Nb doping of SnO2 deposited by a low-cost, scalable chemical bath deposition (CBD) method. We study the effects of doping on compositional, structural, morphological, and device performance when these layers are employed as electron-selective layers (ESLs) in planar-structured PSCs. We use doping concentrations of 0, 1, 5, and 10 mol % Nb to Sn in solution. The ESLs were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and ultraviolet visible spectroscopy. ESLs with an optimum 5 mol % Nb doping yielded, on average, an improvement of all the device photovoltaic parameters with a champion power conversion efficiency of 20.5% (20.1% stabilized).

  • 8.
    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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  • 9.
    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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  • 10.
    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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  • 11.
    Ardo, Shane
    et al.
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA;Univ Calif Irvine, Dept Chem Engn & Mat Sci, Irvine, CA 92697 USA;US DOE, Off Energy Efficiency & Renewable Energy EERE, Fuel Cell Technol Off, EE-3F,1000 Independence Ave SW, Washington, DC 20585 USA.
    Rivas, David Fernandez
    Univ Twente, MESA Inst Nanotechnol, Mesoscale Chem Syst Grp, Enschede, Netherlands.
    Modestino, Miguel A.
    NYU, Dept Chem & Biomol Engn, Brooklyn, NY 11201 USA.
    Greiving, Verena Schulze
    Univ Twente, Dept Sci Technol & Policy Studies, Enschede, Netherlands.
    Abdi, Fatwa F.
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Solar Fuels, Berlin, Germany.
    Llado, Esther Alarcon
    Amolf Inst, Ctr Nanophoton, Amsterdam, Netherlands.
    Artero, Vincent
    Univ Grenoble Alpes, CNRS, CEA, Lab Chim & Biol Metaux, Grenoble, France.
    Ayers, Katherine
    Proton OnSite, Wallingford, CT 06492 USA.
    Battaglia, Corsin
    Empa, Swiss Fed Labs Mat Sci & Technol, Dubendorf, Switzerland.
    Becker, Jan-Philipp
    Forschungszentrum Julich, IEK Photovolta 5, Julich, Germany.
    Bederak, Dmytro
    Univ Groningen, Zernike Inst Adv Mat, Nijenborgh 4, NL-9747 AG Groningen, Netherlands.
    Berger, Alan
    Air Prod & Chem Inc, Allentown, PA 18195 USA.
    Buda, Francesco
    Leiden Univ, Leiden Inst Chem, Leiden, Netherlands.
    Chinello, Enrico
    Ecole Polytech Fed Lausanne, LAPD, Lausanne, Switzerland.
    Dam, Bernard
    Delft Univ Technol, MECS, Dept Chem Engn, Maasweg 9, NL-2629 HZ Delft, Netherlands.
    Di Palma, Valerio
    Eindhoven Univ Technol, Dept Appl Phys, Eindhoven, Netherlands.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Fujii, Katsushi
    Univ Kitakyushu, Inst Environm Sci & Technol, Wakamatsu Ku, Kitakyushu, Fukuoka, Japan.
    Gardeniers, Han
    Univ Twente, MESA Inst Nanotechnol, Mesoscale Chem Syst Grp, Enschede, Netherlands.
    Geerlings, Hans
    Delft Univ Technol, MECS, Dept Chem Engn, Maasweg 9, NL-2629 HZ Delft, Netherlands.
    Hashemi, S. Mohammad H.
    Ecole Polytech Fed Lausanne, Opt Lab LO, Lausanne, Switzerland.
    Haussener, Sophia
    Ecole Polytech Fed Lausanne, LRESE, Lausanne, Switzerland.
    Houle, Frances
    Lawrence Berkeley Natl Lab, Joint Ctr Artificial Photosynthesis & Chem Sci Di, Berkeley, CA 94720 USA.
    Huskens, Jurriaan
    Univ Twente, MESA Inst Nanotechnol, Mol Nanofabricat Grp, Enschede, Netherlands.
    James, Brian D.
    Strateg Anal Inc, Arlington, VA 22203 USA.
    Konrad, Kornelia
    Univ Twente, Dept Sci Technol & Policy Studies, Enschede, Netherlands.
    Kudo, Akihiko
    Tokyo Univ Sci, Fac Sci, Dept Appl Chem, Tokyo 1628601, Japan.
    Kunturu, Pramod Patil
    Univ Twente, MESA Inst Nanotechnol, Mol Nanofabricat Grp, Enschede, Netherlands.
    Lohse, Detlef
    Univ Twente, MESA Inst Nanotechnol, Phys Fluids Grp, Enschede, Netherlands.
    Mei, Bastian
    Univ Twente, MESA Inst Nanotechnol, Photocatalyt Synth Grp, Enschede, Netherlands.
    Miller, Eric L.
    Moore, Gary F.
    Arizona State Univ, Sch Mol Sci, Biodesign Ctr Appl Struct Discovery CASD, Tempe, AZ 85287 USA.
    Muller, Jiri
    Inst Energiteknikk, Kjeller, Norway.
    Orchard, Katherine L.
    Univ Cambridge, Dept Chem, Cambridge, England.
    Rosser, Timothy E.
    Univ Cambridge, Dept Chem, Cambridge, England.
    Saadi, Fadl H.
    CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA.
    Schuttauf, Jan-Willem
    Swiss Ctr Elect & Microtechnol CSEM, PV Ctr, Neuchatel, Switzerland.
    Seger, Brian
    Tech Univ Denmark DTU, Dept Phys, Lyngby, Denmark.
    Sheehan, Stafford W.
    Catalyt Innovat, Fall River, MA 02723 USA.
    Smith, Wilson A.
    Delft Univ Technol, MECS, Dept Chem Engn, Maasweg 9, NL-2629 HZ Delft, Netherlands.
    Spurgeon, Joshua
    Univ Louisville, Conn Ctr Renewable Energy Res, Louisville, KY 40292 USA.
    Tang, Maureen H.
    Drexel Univ, Chem & Biol Engn, Philadelphia, PA 19104 USA.
    van de Krol, Roel
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Solar Fuels, Berlin, Germany.
    Vesborg, Peter C. K.
    Tech Univ Denmark DTU, Dept Phys, Lyngby, Denmark.
    Westerik, Pieter
    Univ Twente, MESA Inst Nanotechnol, Mesoscale Chem Syst Grp, Enschede, Netherlands.
    Pathways to electrochemical solar-hydrogen technologies2018In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 11, no 10, p. 2768-2783Article, review/survey (Refereed)
    Abstract [en]

    Solar-powered electrochemical production of hydrogen through water electrolysis is an active and important research endeavor. However, technologies and roadmaps for implementation of this process do not exist. In this perspective paper, we describe potential pathways for solar-hydrogen technologies into the marketplace in the form of photoelectrochemical or photovoltaic-driven electrolysis devices and systems. We detail technical approaches for device and system architectures, economic drivers, societal perceptions, political impacts, technological challenges, and research opportunities. Implementation scenarios are broken down into short-term and long-term markets, and a specific technology roadmap is defined. In the short term, the only plausible economical option will be photovoltaic-driven electrolysis systems for niche applications. In the long term, electrochemical solar-hydrogen technologies could be deployed more broadly in energy markets but will require advances in the technology, significant cost reductions, and/ or policy changes. Ultimately, a transition to a society that significantly relies on solar-hydrogen technologies will benefit from continued creativity and influence from the scientific community.

  • 12. Arteca, G A
    et al.
    Edvinsson, T
    Elvingson, C
    Compaction of grafted wormlike chains under variable confinement2001In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 3, no 17, p. 3737-3741Article in journal (Refereed)
  • 13.
    Arteca, GA
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Edvinsson, T
    Elvingson, C
    Compaction of grafted wormlike chains under variable confinement2001In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, ISSN 1463-9076, Vol. 3, no 17, p. 3737-3741Article in journal (Refereed)
    Abstract [en]

    We study the mean molecular shape features for a model of wormlike chains with variable persistence length and nonbonded pair interactions. The chains are modelled as end-grafted and confined within an infinite slab with variable thickness. By using two i

  • 14.
    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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  • 15.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Arvizu, Miguel A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Impedance Spectroscopy Modeling of Nickel–Molybdenum Alloys on Porous and Flat Substrates for Applications in Water Splitting2019In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 39, p. 23890-23897Article in journal (Refereed)
    Abstract [en]

    Hydrogen production by splitting water using electrocatalysts powered by renewable energy from solar or wind plants is one promising alternative to produce a carbon-free and sustainable fuel. Earth-abundant and nonprecious metals are, here, of interest as a replacement for scarce and expensive platinum group catalysts. Ni–Mo is a promising alternative to Pt, but the type of the substrate could ultimately affect both the initial growth conditions and the final charge transfer in the system as a whole with resistive junctions formed in the heterojunction interface. In this study, we investigated the effect of different substrates on the hydrogen evolution reaction (HER) of Ni–Mo electrocatalysts. Ni–Mo catalysts (30 atom % Ni, 70 atom % Mo) were sputtered on various substrates with different porosities and conductivities. There was no apparent morphological difference at the surface of the catalytic films sputtered on the different substrates, and the substrates were classified from microporous to flat. The electrochemical characterization was carried out with linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in the frequency range 0.7 Hz–100 kHz. LSV measurements were carried out at direct current (DC) potentials between 200 and −400 mV vs the reversible hydrogen electrode (RHE) in 1 M NaOH encompassing the HER. The lowest overpotentials for HER were obtained for films on the nickel foam at all current densities (−157 mV vs RHE @ 10 mA cm–2), and the overpotentials increased in the order of nickel foil, carbon cloth, fluorine-doped tin oxide, and indium tin oxide glass. EIS data were fitted with two equivalent circuit models and compared for different DC potentials and different substrate morphologies and conductivities. By critical evaluation of the data from the models, the influence of the substrates on the reaction kinetics was analyzed in the high- and low-frequency regions. In the high-frequency region, a strong substrate dependence was seen and interpreted with a Schottky-type barrier, which can be rationalized as being due to a potential barrier in the material heterojunctions or a resistive substrate–film oxide/hydroxide. The results highlight the importance of substrates, the total charge transfer properties in electrocatalysis, and the relevance of different circuit components in EIS and underpin the necessity to incorporate high-conductivity, chemically inert, and work-function-matched substrate–catalysts in the catalyst system.

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  • 16.
    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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  • 17.
    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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  • 18.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stolt, Lars
    Solibro research AB.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. tomas.edvinsson@angstrom.uu.se.
    Optimum Band Gap Energy of ((Ag),Cu)(InGa)Se2 Materials for Combination with NiMo–NiO Catalysts for Thermally Integrated Solar-Driven Water Splitting Applications2019In: Energies, E-ISSN 1996-1073, Vol. 12, article id 4064Article in journal (Refereed)
    Abstract [en]

    Solar-driven water splitting is considered one of the promising future routes to generate fuel in a sustainable way. A carbon-free solar fuel, molecular hydrogen, can here be produced along two different but intimately related routes, photoelectrochemical (PEC) water splitting or photovoltaic electrolysis (PV-electrolysis), where the latter builds on well-established solar cell and electrolysis materials with high efficiency. The PV-electrolysis approach is also possible to construct from an integrated PEC/PV-system avoiding dc-dc converters and enabling heat exchange between the PV and electrolyzer part, to a conventionally wired PV-electrolysis system. In either case, the operating voltage at a certain current needs to be matched with the catalyst system in the electrolysis part. Here, we investigate ((Ag),Cu)(In,Ga)Se-2 ((A)CIGS)-materials with varying Ga-content modules for combination with NiMo-NiO catalysts in alkaline water splitting. The use of (A)CIGS is attractive because of the low cost-to-performance ratio and the possibility to optimize the performance of the system by tuning the band gap of (A)CIGS in contrast to Si technology. The band gap tuning is possible by changing the Ga/(Ga + In) ratio. Optoelectronic properties of the (A)CIGS materials with Ga/(Ga + In) ratios between 0.23 and 0.47 and the voltage and power output from the resulting water splitting modules are reported. Electrolysis is quantified at temperatures between 25 and 60 degrees C, an interval obtainable by varying the thermal heat exchange form a 1-sun illuminated PV module and an electrolyte system. The band gaps of the (A)CIGS thin films were between 1.08 to 1.25 eV and the three-cell module power conversion efficiencies (PCE) ranged from 16.44% with 1.08 eV band gap and 19.04% with 1.17 eV band gap. The highest solar-to-hydrogen (STH) efficiency was 13.33% for the (A)CIGS-NiMo-NiO system with 17.97% module efficiency and electrolysis at 60 degrees C compared to a STH efficiency of 12.98% at 25 degrees C. The increase in STH efficiency with increasing temperature was more notable for lower band gaps as these are closer to the overpotential threshold for performing efficient solar-driven catalysis, while only a modest improvement can be obtained by utilizing thermal exchange for a band gap matched PV-catalysts system. The results show that usage of cost-effective and stable thin film PV materials and earth abundant catalysts can provide STH efficiencies beyond 13% even with PV modules with modest efficiency.

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  • 19.
    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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  • 20.
    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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    FULLTEXT01
  • 21.
    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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  • 22. 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.

  • 23. Boschloo, G.
    et al.
    Marinado, T.
    Nonomura, K.
    Edvinsson, T.
    Agrios, A. G.
    Hagberg, D. P.
    Sun, L.
    Quintana, M.
    Karthikeyan, C. S.
    Thelakkat, M.
    Hagfeldt, A.
    A comparative study of a polyene-diphenylaniline dye and Ru(dcbpy)(2)(NCS)(2) in electrolyte-based and solid-state dye-sensitized solar cells2008In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, no 20, p. 7214-7217Article in journal (Refereed)
  • 24. Boschloo, Gerrit
    et al.
    Edvinsson, Tomas
    Hagfeldt, Anders
    Dye-sensitized nanostructured ZnO Electrodes for solar cell applications2007In: Nanostructured materials for solar energy conversion / [ed] Tetsuo Soga, Amsterdam: Elsevier Science , 2007Chapter in book (Refereed)
  • 25.
    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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  • 26.
    D'Amario, Luca
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Free Univ Berlin, Dept Phys, Arnimallee 14, D-14195 Berlin, Germany..
    Stella, Maria Bruna
    Univ Pisa, Dept Chem & Ind Chem, Via Moruzzi 13, I-56124 Pisa, Italy..
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Persico, Maurizio
    Univ Pisa, Dept Chem & Ind Chem, Via Moruzzi 13, I-56124 Pisa, Italy..
    Messinger, Johannes
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Umeå Univ, Chem Biol Ctr, Dept Chem, S-90187 Umeå, Sweden..
    Dau, Holger
    Free Univ Berlin, Dept Phys, Arnimallee 14, D-14195 Berlin, Germany..
    Towards time resolved characterization of electrochemical reactions: electrochemically-induced Raman spectroscopy2022In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 13, no 36, p. 10734-10742Article in journal (Refereed)
    Abstract [en]

    Structural characterization of transient electrochemical species in the sub-millisecond time scale is the all-time wish of any electrochemist. Presently, common time resolution of structural spectro-electrochemical methods is about 0.1 seconds. Herein, a transient spectro-electrochemical Raman setup of easy implementation is described which allows sub-ms time resolution. The technique studies electrochemical processes by initiating the reaction with an electric potential (or current) pulse and analyses the product with a synchronized laser pulse of the modified Raman spectrometer. The approach was validated by studying a known redox driven isomerization of a Ru-based molecular switch grafted, as monolayer, on a SERS active Au microelectrode. Density-functional-theory calculations confirmed the spectral assignments to sub-ms transient species. This study paves the way to a new generation of time-resolved spectro-electrochemical techniques which will be of fundamental help in the development of next generation electrolizers, fuel cells and batteries.

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  • 27.
    Dürr, Robin N.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Université Paris-Saclay.
    Maltoni, Pierfrancesco
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Feng, Shihui
    Ghorai, Sagar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Ström, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tai, Cheuk-Wai
    Araujo, Rafael
    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.
    Clearing Up Discrepancies in 2D and 3D Nickel Molybdate Hydrate Structures2024In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 63, no 5Article in journal (Refereed)
    Abstract [en]

    When electrocatalysts are prepared, modification of the morphology is a common strategy to enhance their electrocatalytic performance. In this work, we have examined and characterized nanorods (3D) and nanosheets (2D) of nickel molybdate hydrates, which previously have been treated as the same material with just a variation in morphology. We thoroughly investigated the materials and report that they contain fundamentally different compounds with different crystal structures, chemical compositions, and chemical stabilities. The 3D nanorod structure exhibits the chemical formula NiMoO4·0.6H2O and crystallizes in a triclinic system, whereas the 2D nanosheet structures can be rationalized with Ni3MoO5–0.5x(OH)x·(2.3 – 0.5x)H2O, with a mixed valence of both Ni and Mo, which enables a layered crystal structure. The difference in structure and composition is supported by X-ray photoelectron spectroscopy, ion beam analysis, thermogravimetric analysis, X-ray diffraction, electron diffraction, infrared spectroscopy, Raman spectroscopy, and magnetic measurements. The previously proposed crystal structure for the nickel molybdate hydrate nanorods from the literature needs to be reconsidered and is here refined by ab initio molecular dynamics on a quantum mechanical level using density functional theory calculations to reproduce the experimental findings. Because the material is frequently studied as an electrocatalyst or catalyst precursor and both structures can appear in the same synthesis, a clear distinction between the two compounds is necessary to assess the underlying structure-to-function relationship and targeted electrocatalytic properties.

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  • 28.
    Dürr, Robin N.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Maltoni, Pierfrancesco
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Tian, Haining
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Jousselme, Bruno
    Univ Paris Saclay, CEA, CNRS, NIMBE,LICSEN, F-91191 Gif Sur Yvette, France.
    Hammarström, Leif
    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, 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.
    From NiMoO4 to γ-NiOOH: Detecting the Active Catalyst Phase by Time Resolved in Situ and Operando Raman Spectroscopy2021In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 15, no 8, p. 13504-13515Article in journal (Refereed)
    Abstract [en]

    Water electrolysis powered by renewable energies is a promising technology to produce sustainable fossil free fuels. The development and evaluation of effective catalysts are here imperative; however, due to the inclusion of elements with different redox properties and reactivity, these materials undergo dynamical changes and phase transformations during the reaction conditions. NiMoO4 is currently investigated among other metal oxides as a promising noble metal free catalyst for the oxygen evolution reaction. Here we show that at applied bias, NiMoO4·H2O transforms into γ-NiOOH. Time resolved operando Raman spectroscopy is utilized to follow the potential dependent phase transformation and is collaborated with elemental analysis of the electrolyte, confirming that molybdenum leaches out from the as-synthesized NiMoO4·H2O. Molybdenum leaching increases the surface coverage of exposed nickel sites, and this in combination with the formation of γ-NiOOH enlarges the amount of active sites of the catalyst, leading to high current densities. Additionally, we discovered different NiMoO4 nanostructures, nanoflowers, and nanorods, for which the relative ratio can be influenced by the heating ramp during the synthesis. With selective molybdenum etching we were able to assign the varying X-ray diffraction (XRD) pattern as well as Raman vibrations unambiguously to the two nanostructures, which were revealed to exhibit different stabilities in alkaline media by time-resolved in situ and operando Raman spectroscopy. We advocate that a similar approach can beneficially be applied to many other catalysts, unveiling their structural integrity, characterize the dynamic surface reformulation, and resolve any ambiguities in interpretations of the active catalyst phase.

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  • 29.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    A concentrated effort2019In: NATURE ENERGY, ISSN 2058-7546, Vol. 4, no 5, p. 354-355Article in journal (Other academic)
    Abstract [en]

    While recent gains in the efficiency of photoelectrochemical devices for hydrogen production are encouraging, high efficiency is rarely combined with high power output, which is important for large-scale viability. Towards this goal, researchers now demonstrate a promising thermally integrated device driven by concentrated solar irradiation.

  • 30.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    High Performance Materials for Solar Fuel Generation and Pathways to Utilization of IR-Photons2017In: Proceeding, MRS 2017, 2017, p. 05--05, article id ES02.03.05Conference paper (Refereed)
  • 31.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lågdimensionella material för generering av solbränsle2017Conference paper (Other academic)
  • 32.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    On the Size and Shape of Polymers and Polymer Complexes: A Computational and Light Scattering Study2002Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Detailed characterization of size and shape of polymers, and development of methods to elucidate the mechanisms behind shape transitions are central issues in this thesis. In particular we characterize grafted polymer chains under confinement in terms of the chain entanglement complexity and mean molecular size. Confinement of polymers into small regions can drastically affect the structural and mechanical properties, and make these systems convenient for a large number of applications, including the design of lubricants, coatings, and various biotechnical applications.

    Using Monte Carlo simulations with a model including both persistence length and intramolecular non-bonded interaction, we find two regimes of polymer behaviour: i) soft mushrooms, where confinement successively flattens the chains with accompanying change in the folding complexity, and ii) hard mushrooms where the compact structures appear to resist confinement and the only way to reorganize the entanglements is by flattening under strong confinement. We also show that a simultaneous use of mean molecular size and chain entanglement complexity renders the possibility to create configurational "phase" diagrams for a wide range of polymers. We have further introduced a new descriptor of folding complexity, the path-space ratio, ζα which captures essential features of molecular shape beyond those conveyed by mean size and asphericity.

    This thesis also contains results of light scattering measurements on supramolecular complexes formed when mixing an adamantane end-capped star polymer with a β-cyclodextrin polymer. The specific interactions result in an interplay between the association of the end-caps and a strong inclusion interaction between adamantane and β-cyclodextrin.

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  • 33. Edvinsson, Tomas
    Optical Quantum Confinement and Photocatalysis2014Conference paper (Other academic)
  • 34.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Optical quantum confinement and photocatalytic properties in two-, one- and zero-dimensional nanostructures2018In: Royal Society Open Science, E-ISSN 2054-5703, Vol. 5, no 9, article id 180387Article in journal (Refereed)
    Abstract [en]

    Low-dimensional nanomaterials have been explored extensively in the last decades, partly fuelled by the new possibilities for tuning and controlling their electronic properties. In a broader perspective within catalysis, two-, one- and zero-dimensional (2D, 1D and 0D) inorganic nanomaterials represent a bridge between the selectivity of molecular catalysts and the high performance and stability of inorganic catalysts. As a consequence of the low dimensions, higher surface areas are obtained but also introduce new physics and increased tuneability of the electronic states in the nanostructured system. Herein, we derive the commonly used equations for optical transitions and carrier confinement in semiconductors and discuss their effect on the optical and photocatalytic properties of direct band and indirect band gap materials. In particular, the physical properties of the optical and photocatalytic properties of Fe2O3 and ZnO will be used to exemplify the effects of the low dimensionality. Carrier confinement effects with changes in the density of states, band gap/shift of band edges will be outlined together with their effects on the tuneability of the material and their wider application as photocatalytic materials.

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  • 35.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Resonant and off-resonant Raman spectroscopy for analysis of solar energy material2017Conference paper (Refereed)
  • 36.
    Edvinsson, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Arteca, Gustavo A.
    Elvingson, Christer
    Path-Space Ratio as a Molecular Shape Descriptor of Polymer Conformation2003In: Journal of Chemical Information and Computer Science, Vol. 43, p. 126-133Article in journal (Refereed)
  • 37.
    Edvinsson, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Elvingson, Christer
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I.
    Arteca, Gustavo
    Effect of compression on the molecular shape of polymer mushrooms with variable stiffness2002In: Journal of chemical physics, Vol. 116, p. 9510-Article in journal (Refereed)
  • 38.
    Edvinsson, Tomas
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry.
    Elvingson, Christer
    Gustavo, Arteca
    Variations in molecular compactness and chain entanglement during the compression of grafted polymers2000In: MACROMOLECULAR THEORY AND SIMULATIONS, ISSN 1022-1344, Vol. 9, no 7, p. 398-406Article in journal (Refereed)
    Abstract [en]

    Characterizing the effect of geometrical confinement on mean polymer shape is an important step towards understanding and controlling molecular behaviour at interfaces. In this work, we study the configurational transitions and molecular shape changes tha

  • 39. Edvinsson, Tomas
    et al.
    Li, Chen
    Pschirer, Neil
    Schoeneboom, Jan
    Eickemeyer, Felix
    Sens, Ruediger
    Boschloo, Gerrit
    Herrmann, Andreas
    Muellen, Klaus
    Hagfeldt, Anders
    Intramolecular charge-transfer tuning of perylenes: Spectroscopic features and performance in Dye-sensitized solar cells2007In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, no 42, p. 15137-15140Article in journal (Refereed)
  • 40.
    Edvinsson, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Pschirer, Niel
    Schöneboom, Jan
    Eickemeyer, Felix
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Photoinduced electron transfer from a terrylene dye to TiO2: Quantification of band edge shift effects2009In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 357, no 1-3, p. 124-131Article in journal (Refereed)
    Abstract [en]

    A terrylene chromophore exhibiting a high extinction coefficient has been developed as a sensitizer for photovoltaic applications. The photophysical and photochemical properties of the dye were analyzed both experimentally and theoretically. Terrylene-sensitized nanocrystalline TiO2 solar cells yielded good photocurrents providing more than 60% in external quantum efficiency. The photoinduced electron transfer from the dye to TiO2 was found to be very sensitive to conduction band edge shifts in TiO2 induced, either by changes in the composition of the redox electrolyte or by UV-illumination. This sensitivity was observed in quantum efficiencies for photocurrent generation of terrylene-sensitized solar cells and in photoinduced absorption experiments. The conduction band shifts were quantified using charge extraction methods. The observed sensitivity of the injection efficiency suggests that photoinduced electron transfer occurs from the relaxed excited state, possibly due to poor electronic coupling between TMIMA excited states and TiO2 conduction band states.

  • 41.
    Edvinsson, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Råsmark, Per Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Elvingson, Christer
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Cluster identification and percolation analysis using a recursive algorithm1999In: Molecular Simulation, ISSN 0892-7022, E-ISSN 1029-0435, Vol. 23, no 3, p. 169-190Article in journal (Refereed)
    Abstract [en]

    A recursive algorithm for sampling properties of physical clusters such as size distribution andpercolation is presented. The approach can be applied to any system with periodic boundaryconditions, given a spatial definition of a cluster. We also introduce some modifications in thealgorithm that increases the efficiency considerably if one is only interested in percolationanalysis. The algorithm is implemented in Fortran 90 and is compared with a number ofiterative algorithms. The recursive cluster identification algorithm is somewhat slower than theiterative methods at low volume fraction but is at least as fast at high densities. The percolationanalysis, however, is considerably faster using recursion, for all systems studied. We also notethat the CPU time using recursion is independent on the static allocation of arrays, whereas theiterative method strongly depends on the size of the initially allocated arrays.

  • 42. Fan, Lizhou
    et al.
    Zhang, Biaobiao
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Dharanipragada, N. V. R. Aditya
    Timmer, Brian J. J.
    Zhang, Fuguo
    Sheng, Xia
    Liu, Tianqi
    Meng, Qijun
    Inge, A. Ken
    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.
    Sun, Licheng
    Molecular Functionalization of NiO Nanocatalyst for Enhanced Water Oxidation by Electronic Structure Engineering2020In: ChemSusChem, Vol. 13, no 22, p. 5901-5909Article in journal (Refereed)
    Abstract [en]

    Abstract Tuning the local environment of nanomaterial-based catalysts has emerged as an effective approach to optimize their oxygen evolution reaction (OER) performance, yet the controlled electronic modulation around surface active sites remains a great challenge. Herein, directed electronic modulation of NiO nanoparticles was achieved by simple surface molecular modification with small organic molecules. By adjusting the electronic properties of modifying molecules, the local electronic structure was rationally tailored and a close electronic structure-activity relationship was discovered: the increasing electron-withdrawing modification readily decreased the electron density around surface Ni sites, accelerating the reaction kinetics and improving OER activity, and vice versa. Detailed investigation by operando Raman spectroelectrochemistry revealed that the electron-withdrawing modification facilitates the charge-transfer kinetics, stimulates the catalyst reconstruction, and promotes abundant high-valent γ-NiOOH reactive species generation. The NiO−C6F5 catalyst, with the optimized electronic environment, exhibited superior performance towards water oxidation. This work provides a well-designed and effective approach for heterogeneous catalyst fabrication under the molecular level.

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  • 43.
    Ferdowsi, Parnian
    et al.
    Univ Fribourg, Soft Matter Phys, Adolph Merkle Inst, CH-1700 Fribourg, Switzerland;Univ Guilan, Fac Engn, Dept Text Engn, Rasht 416353756, Iran;Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Dept Chem, Lab Photomol Sci, CH-1015 Lausanne, Switzerland.
    Saygili, Yasemin
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Dept Chem, Lab Photomol Sci, CH-1015 Lausanne, Switzerland.
    Jazaeri, Farzan
    Ecole Polytech Fed Lausanne, Integrated Circuits Lab, Dept Elect Engn, CH-2002 Neuchatel, Switzerland.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mokhtari, Javad
    Univ Guilan, Fac Engn, Dept Text Engn, Rasht 416353756, Iran.
    Zakeeruddin, Shaik M.
    Ecole Polytech Fed Lausanne, Dept Chem, Lab Photon & Interfaces, Inst Chem Sci, CH-1015 Lausanne, Switzerland.
    Liu, Yuhang
    Ecole Polytech Fed Lausanne, Dept Chem, Lab Photon & Interfaces, Inst Chem Sci, CH-1015 Lausanne, Switzerland.
    Graetzel, Michael
    Ecole Polytech Fed Lausanne, Dept Chem, Lab Photon & Interfaces, Inst Chem Sci, CH-1015 Lausanne, Switzerland.
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Dept Chem, Lab Photomol Sci, CH-1015 Lausanne, Switzerland.
    Molecular Engineering of Simple Metal-Free Organic Dyes Derived from Triphenylamine for Dye-Sensitized Solar Cell Applications2020In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 13, no 1, p. 212-220Article in journal (Refereed)
    Abstract [en]

    Two new metal-free organic sensitizers, L156 and L224, were designed, synthesized, and characterized for application in dye-sensitized solar cells (DSCs). The structures of the dyes contain a triphenylamine (TPA) segment and 4-(benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid as electron-rich and -deficient moieties, respectively. Two different pi bridges, thiophene and 4,8-bis(4-hexylphenyl)benzo[1,2-b:4,5-b ']dithiophene, were used for L156 and L224, respectively. The influence of iodide/triiodide, [Co(bpy)(3)](2+/3+) (bpy=2,2 '-bipyridine), and [Cu(tmby)(2)](2+/+) (tmby=4,4 ',6,6 '-tetramethyl-2,2 '-bipyridine) complexes as redox electrolytes and 18 NR-T and 30 NR-D transparent TiO2 films on the DSC device performance was investigated. The L156-based DSC with [Cu(tmby)(2)](2+/+) complexes as the redox electrolyte resulted in the best performance of 9.26 % and a remarkably high open-circuit voltage value of 1.1 V (1.096 V), with a short-circuit current of 12.2 mA cm(-2) and a fill factor of 0.692, by using 30 NR-D TiO2 films. An efficiency of up to 21.9 % was achieved under a 1000 lx indoor light source, which proved that dye L156 was also an excellent candidate for indoor applications. The maximal monochromatic incident-photon-to-current conversion efficiency of L156-30 NR-D reached up to 70 %.

  • 44.
    Ferdowsi, Parnian
    et al.
    Univ Guilan, Fac Engn, Dept Text Engn, Rasht 416353756, Iran.;Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photomol Sci, Dept Chem, CH-1015 Lausanne, Switzerland..
    Saygili, Yasemin
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photomol Sci, Dept Chem, CH-1015 Lausanne, Switzerland..
    Zhang, Weiwei
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photon & Interfaces, Dept Chem, CH-1015 Lausanne, Switzerland..
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kavan, Ladislav
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photon & Interfaces, Dept Chem, CH-1015 Lausanne, Switzerland.;J Heyrovsky Inst Phys Chem, Prague 1823, Czech Republic..
    Mokhtari, Javad
    Univ Guilan, Fac Engn, Dept Text Engn, Rasht 416353756, Iran..
    Zakeeruddin, Shaik M.
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photon & Interfaces, Dept Chem, CH-1015 Lausanne, Switzerland..
    Grätzel, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photon & Interfaces, Dept Chem, CH-1015 Lausanne, Switzerland..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photomol Sci, Dept Chem, CH-1015 Lausanne, Switzerland..
    Molecular Design of Efficient Organic D-A-pi-A Dye Featuring Triphenylamine as Donor Fragment for Application in Dye-Sensitized Solar Cells2018In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 11, no 2, p. 494-502Article in journal (Refereed)
    Abstract [en]

    A metal-free organic sensitizer, suitable for the application in dye-sensitized solar cells (DSSCs), has been designed, synthesized and characterized both experimentally and theoretically. The structure of the novel donor-acceptor--bridge-acceptor (D-A-pi-A) dye incorporates a triphenylamine (TPA) segment and 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)benzoic acid (BTEBA). The triphenylamine unit is widely used as an electron donor for photosensitizers, owing to its nonplanar molecular configuration and excellent electron-donating capability, whereas 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)benzoic acid is used as an electron acceptor unit. The influences of I-3(-)/I-, [Co(bpy)(3)](3+/2+) and [Cu(tmby)(2)](2+/+) (tmby=4,4,6,6-tetramethyl-2,2-bipyridine) as redox electrolytes on the DSSC device performance were also investigated. The maximal monochromatic incident photon-to-current conversion efficiency (IPCE) reached 81% and the solar light to electrical energy conversion efficiency of devices with [Cu(tmby)(2)](2+/+) reached 7.15%. The devices with [Co(bpy)(3)](3+/2+) and I-3(-)/I- electrolytes gave efficiencies of 5.22% and 6.14%, respectively. The lowest device performance with a [Co(bpy)(3)](3+/2+)-based electrolyte is attributed to increased charge recombination.

  • 45.
    Fondell, Mattis
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jacobsson, Jesper T.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Boman, Mats
    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.
    Optical quantum confinement in low dimensional hematite2014In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 10, p. 3352-3363Article in journal (Refereed)
    Abstract [en]

    Hematite is considered to be a promising material for various applications, including for example photoelectrochemical cells for solar hydrogen production. Due to limitations in the charge transport properties hematite needs to be in the form of low-dimensional particles or thin films in several of these applications. This may however affect the optical properties, introducing additional complications for efficient design of photo-active devices. In this paper the optical absorption is analyzed in detail as a function of film thickness for 35 thin films of hematite ranging between 2 and 70 nm. Hematite was deposited by atomic layer deposition on FTO-substrates using Fe(CO)(5) and O-2 as precursors. It was found that for film thicknesses below 20 nm the optical properties are severely affected as a consequence of quantum confinement. One of the more marked effects is a blue shift of up to 0.3 eV for thinner films of both the indirect and direct transitions, as well as a 0.2 eV shift of the absorption maximum. The data show a difference in quantum confinement for the indirect and the direct transitions, where the probability for the indirect transition decreases markedly and essentially disappears for the thinnest films. Raman measurements showed no peak shift or change in relative intensity for vibrations for the thinnest films indicating that the decrease in indirect transition probability could not be assigned to depression of any specific phonon but instead seems to be a consequence of isotropic phonon confinement. The onset of the indirect transition is found at 1.75 eV for the thickest films and shifted to 2.0 eV for the thinner films. Two direct transitions are found at 2.15 eV and 2.45 eV, which are blue shifted 0.3 and 0.45 eV respectively, when decreasing the film thickness from 20 to 4 nm. Low dimensional hematite, with dimensions small enough for efficient charge transport, thus has a substantially lower absorption in the visible region than expected from bulk values. This knowledge of the intrinsic optical behavior of low dimensional hematite will be of importance in the design of efficient photo-active devices.

  • 46.
    Geng, Xinjian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Abdellah, Mohamed
    Peafowl Solar Power AB, R&D Div, S-75643 Uppsala, Sweden.;South Valley Univ, Qena Fac Sci, Dept Chem, Qena 83523, Egypt..
    Vadell, Robert Bericat
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Folkenant, Matilda
    Peafowl Solar Power AB, R&D Div, S-75643 Uppsala, Sweden.;Altris AB, Kungsgatan 70b, S-75318 Uppsala, Sweden..
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Peafowl Solar Power AB, R&D Div, S-75643 Uppsala, Sweden.;Polish Acad Sci IChF PAN, Inst Phys Chem, PL-01224 Warsaw, Poland..
    Direct Plasmonic Solar Cell Efficiency Dependence on Spiro-OMeTAD Li-TFSI Content2021In: Nanomaterials, E-ISSN 2079-4991, Vol. 11, no 12, article id 3329Article in journal (Refereed)
    Abstract [en]

    The proliferation of the internet of things (IoT) and other low-power devices demands the development of energy harvesting solutions to alleviate IoT hardware dependence on single-use batteries, making their deployment more sustainable. The propagation of energy harvesting solutions is strongly associated with technical performance, cost and aesthetics, with the latter often being the driver of adoption. The general abundance of light in the vicinity of IoT devices under their main operation window enables the use of indoor and outdoor photovoltaics as energy harvesters. From those, highly transparent solar cells allow an increased possibility to place a sustainable power source close to the sensors without significant visual appearance. Herein, we report the effect of hole transport layer Li-TFSI dopant content on semi-transparent, direct plasmonic solar cells (DPSC) with a transparency of more than 80% in the 450-800 nm region. The findings revealed that the amount of oxidized spiro-OMeTAD (spiro(+)TFSI(-)) significantly modulates the transparency, effective conductance and conditions of device performance, with an optimal performance reached at around 33% relative concentration of Li-TFSI concerning spiro-OMeTAD. The Li-TFSI content did not affect the immediate charge extraction, as revealed by an analysis of electron-phonon lifetime. Hot electrons and holes were injected into the respective layers within 150 fs, suggesting simultaneous injection, as supported by the absence of hysteresis in the I-V curves. The spiro-OMeTAD layer reduces the Au nanoparticles' reflection/backscattering, which improves the overall cell transparency. The results show that the system can be made highly transparent by precise tuning of the doping level of the spiro-OMeTAD layer with retained plasmonics, large optical cross-sections and the ultrathin nature of the devices.

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  • 47.
    Grånäs, Oscar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Timneanu, Nicusor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Eliah Dawod, Ibrahim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ragazzon, Davide
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Trygg, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Souvatzis, Petros
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Femtosecond bond breaking and charge dynamics in ultracharged amino acids2019In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 151, no 14, article id 144307Article in journal (Refereed)
    Abstract [en]

    Historically, structure determination of nanocrystals, proteins, and macromolecules required the growth of high-quality crystals sufficiently large to diffract X-rays efficiently while withstanding radiation damage. The development of the X-ray free-electron laser has opened the path toward high resolution single particle imaging, and the extreme intensity of the X-rays ensures that enough diffraction statistics are collected before the sample is destroyed by radiation damage. Still, recovery of the structure is a challenge, in part due to the partial fragmentation of the sample during the diffraction event. In this study, we use first-principles based methods to study the impact of radiation induced ionization of six amino acids on the reconstruction process. In particular, we study the fragmentation and charge rearrangement to elucidate the time scales involved and the characteristic fragments occurring.

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  • 48.
    Gu, Xiuquan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. China University of Mining and Technology.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    ZnO nanomaterials: Strategies for improvement of photocatalytic and photoelectrochemical activities2019In: Current Developments in Photocatalysis and Photocatalytic Materials: New Horizons in Photocatalysis / [ed] Xinchen Wang, Masakazu Anpo & Xianzhi Fu, Amsterdam: Elsevier, 2019, 1, p. 231-244Chapter in book (Refereed)
    Abstract [en]

    ZnO is a promising material for photoanodes and applications within photocatalysis, due to its controllable morphology, excellent stability, and high velocity (>100 cm2 V−1·s−1) for charge carrier migration. In addition, the deep lying valence band edge provides a high driving force for many oxidation reactions, including water oxidation. For a tailored artificial light such as UV light–emitting diodes, ZnO photocatalysis can be very effective while the relatively wide bandgap of ∼3.3 eV yields a limitation in utilizing the full potential of the solar spectrum for photocatalysis. A lot of effort has been made to enhance the photocatalytic (PC) activity of ZnO, either by extending the absorption into the visible range by doping or by more efficient use of the absorbed photons in the UV range. In our previous studies, we have demonstrated that the PC activity of ZnO nanocrystals could be enhanced via morphology tuning, the formation of a Schottky junction with Au or Ag nanoparticles, and the combination with narrow-bandgap semiconductors. We have also shown the photoelectrochemical activity of ZnO nanorod arrays can be improved through thermal treatment or being modified with a ZnS thin layer. Another strategy is to control the electronic properties in ZnO by quantum confinement, which provides tunability of the electronic levels and introduces the ability to target specific reactions at the expense of widening the bandgap. In this chapter, we succinctly present the current progress in ZnO photocatalysis, strategies to improve and control the PC activity, and bring up the present and future prospect of ZnO as a photocatalyst.

  • 49. Hagberg, Daniel P.
    et al.
    Edvinsson, Tomas
    Marinado, Tannia
    Boschloo, Gerrit
    Hagfeldt, Anders
    Sun, Licheng
    A novel organic chromophore for dye-sensitized nanostructured solar cells2006In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 21, p. 2245-2247Article in journal (Refereed)
  • 50.
    Husain, Sajid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Chen, Xin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Gupta, Rahul
    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.
    Kumar, Prabhat
    Czech Acad Sci, Dept Thin Films & Nanostruct, Inst Phys, Prague, Czech Republic.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    F. García-Sánchez, F.
    Univ Salamanca, Dept Fis Aplicada, Salamanca, Spain.
    Brucas, Rimantas
    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, India.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Kumar, Ankit (Contributor)
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Large Damping-Like Spin–Orbit Torque in a 2D Conductive 1T-TaS2 Monolayer2020In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 20, no 9, p. 6372-6380Article in journal (Refereed)
    Abstract [en]

    A damping-like spin-orbit torque (SOT) is a prerequisite for ultralow-power spin logic devices. Here, we report on the damping-like SOT in just one monolayer of the conducting transition-metal dichalcogenide (TMD) TaS2 interfaced with a NiFe (Py) ferromagnetic layer. The charge-spin conversion efficiency is found to be 0.25 +/- 0.03 in TaS2(0.88)/Py(7), and the spin Hall conductivity (14.9 x 10(s) h/2e Omega(-1) m(-1) is found to be superior to values reported for other TMDs. We also observed sizable field-like torque in this heterostructure. The origin of this large damping-like SOT can be found in the interfacial properties of the TaS2/Py heterostructure, and the experimental findings are complemented by the results from density functional theory calculations. It is envisioned that the interplay between interfacial spinorbit coupling and crystal symmetry yielding large damping-like SOT. The dominance of damping-like torque demonstrated in our study provides a promising path for designing the next-generation conducting TMD-based low-powered quantum memory devices.

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