Repository of University of Nova Gorica

Search the repository
A+ | A- | Help | SLO | ENG

Query: search in
search in
search in
search in
* old and bolonia study programme

Options:
  Reset


11 - 20 / 48
First pagePrevious page12345Next pageLast page
11.
Photocatalytic Activity of Zirconium- and Manganese- Codoped Titania in Aqueous Media: The Role of the Metal Dopant and its Incorporation Site
Nataša Novak Tušar, Iztok Arčon, O. L. Pliekhov, Urška Lavrenčič Štangar, 2016, original scientific article

Abstract: The development of efficient TiO2-based photocatalysts for water treatment is mainly performed by doping with transition metals or by establishing junctions between different phases, metal–semiconductor or semiconductor–semiconductor. We present, for the first time, the synthesis of Zr- and Mn-modified TiO2 by a redesigned sol–gel technique that allows the formation of heterometallic bridges on the TiO2 surface. Cations of the doping metals are located in the pores of mesoporous anatase and attached to the crystalline TiO2 walls. The presence of the Zr enhances the photoactivity of the TiO2 catalyst. However, the introduction of Mn decreases the photocatalytic efficiency in a nonadditive manner. The inhibition effect was assigned to the side reaction between hydroxyl radicals and Mn ions. The fact that Mn effectively scavenges the hydroxyl radicals and, consequently, inhibits the whole oxidation process is direct proof that hydroxyl radicals are the main reactive species in the photocatalytic oxidative processes on TiO2 surfaces in aqueous media and the process of COH generation is the rate-determining step, which was confirmed using a method based on the decolorization of a commercial dye Bezaktiv Blau in a reaction with Fenton’s reagent as a source of hydroxyl radicals.
Found in: ključnih besedah
Summary of found: ...doping, manganese, oxidation, X-ray absorption spectroscopy, zirconium...
Keywords: doping, manganese, oxidation, X-ray absorption spectroscopy, zirconium
Published: 21.07.2016; Views: 2425; Downloads: 0
.pdf Fulltext (577,49 KB)

12.
Basics and applications of photothermal beam deflection spectroscopy;
Dorota Korte, 2016, published scientific conference contribution abstract (invited lecture)

Found in: ključnih besedah
Keywords: beam deflection spectroscopy, photothermal effects, material characterization
Published: 07.11.2016; Views: 2932; Downloads: 499
.pdf Fulltext (1,07 MB)

13.
Determination of petrophysical properties of sedimentary rocks by optical methods
Dorota Korte, Dejan Kaukler, Mattia Fanetti, Humberto Cabrera, Efrain Daubronte, Mladen Franko, 2017, original scientific article

Found in: ključnih besedah
Summary of found: ...sedimentary rocks, beam deflection spectroscopy, grain size distribution, petrophysical properties, chemical composition...
Keywords: sedimentary rocks, beam deflection spectroscopy, grain size distribution, petrophysical properties, chemical composition
Published: 06.02.2017; Views: 2488; Downloads: 0
.pdf Fulltext (1014,14 KB)

14.
Operando characterization of batteries using x-ray absorption spectroscopy: advances at the beamline XAFS at synchrotron Elettra
Nicola Novello, Iztok Arčon, Lorenzo Stievano, Robert Dominko, marco Giorgetti, Giuliana Aquilanti, Luca Ivanc Olivieri, 2017, original scientific article

Abstract: X-ray absorption spectroscopy is a synchrotron radiation based technique that is able to provide information on both local structure and electronic properties in a chemically selective manner. It can be used to characterize the dynamic processes that govern the electrochemical energy storage in batteries, and to shed light on the redox chemistry and changes in structure during galvanostatic cycling to design cathode materials with improved properties. Operando XAS studies have been performed at beamline XAFS at Elettra on different systems. For Li-ion batteries, a multiedge approach revealed the role of the different cathode components during the charge and discharge of the battery. In addition, Li-S batteries for automotive applications were studied. Operando sulfur K-edge XANES and EXAFS analysis was used to characterize the redox chemistry of sulfur, and to relate the electrochemical mechanism to its local structure.
Found in: ključnih besedah
Keywords: operando studies, x-ray absorption spectroscopy, Li-ion batteries, Li-S batteries
Published: 03.03.2017; Views: 4122; Downloads: 0
.pdf Fulltext (1,59 MB)

15.
The mechanism of Li2S activation in lithium-sulfur batteries: Can we avoid the polysulfide formation?
Robert Dominko, Tim-Patric Fellinger, Markus Antonietti, Giuliana Aquilanti, Lorenzo Stievano, Iztok Arčon, Elena Tchernychova, Laurent Chabanne, Alen Vižintin, 2017, original scientific article

Abstract: Electrochemical reactions in the LieS batteries are considered as a multistep reaction process with at least 2e3 equilibrium states. Here we report a possibility of having a conversion of Li2S into sulfur without detectible formation of polysulfides. That was confirmed by using a novel material system consisting of carbon coated Li2S particles prepared by carbothermal reduction of Li2SO4. Two independent in operando measurements showed direct oxidation of Li2S into sulfur for this system, with almost negligible formation of polysulfides at potentials above 2.5 V vs. Li/Liþ. Our results link the diversity of first charge profiles in the literature to the Li2S oxidation mechanism and show the importance of ionic wiring within the material. Furthermore, we demonstrate that the Li2S oxidation mechanism depends on the relative amount of soluble sulfur in the electrolyte. By controlling the type and the amount of electrolyte within the encapsulating carbon shell, it is thereby possible to control the reaction mechanism of Li2S activation.
Found in: ključnih besedah
Summary of found: ...Lithium-sulfur batteries Li2S active material XAS UV/Vis spectroscopy Li2S activation...
Keywords: Lithium-sulfur batteries Li2S active material XAS UV/Vis spectroscopy Li2S activation
Published: 03.03.2017; Views: 3177; Downloads: 0
.pdf Fulltext (2,98 MB)

16.
Time- and angle-resolved photoemission spectroscopy with optimized high-harmonic pulses using frequency-doubled Ti:Sapphire lasers
Steffen Eich, Jurij Urbančič, 2014, original scientific article

Abstract: Time- and angle-resolved photoemission spectroscopy (trARPES) using femtosecond extreme ultraviolet high harmonics has recently emerged as a powerful tool for investigating ultrafast quasiparticle dynamics in correlated-electron materials. However, the full potential of this approach has not yet been achieved because, to date, high harmonics generated by 800 nm wavelength Ti:Sapphire lasers required a trade-off between photon flux, energy and time resolution. Photoemission spectroscopy requires a quasi-monochromatic output, but dispersive optical elements that select a single harmonic can significantly reduce the photon flux and time resolution. Here we show that 400 nm driven high harmonic extreme-ultraviolet trARPES is superior to using 800 nm laser drivers since it eliminates the need for any spectral selection, thereby increasing photon flux and energy resolution to <150 meV while preserving excellent time resolution of about 30 fs.
Found in: ključnih besedah
Keywords: angle-resolved photoemission spectroscopy, ARPES, high harmonic generation, ultrafast surface science
Published: 20.04.2017; Views: 3080; Downloads: 0
.pdf Fulltext (1,80 MB)

17.
Extraction of Organochlorine Pesticides from Plastic Pellets and Plastic Type Analysis
Špela Koren, Manca Kovač Viršek, Petra Makorič, Maryline Pflieger, 2017, review article

Abstract: Plastic resin pellets, categorized as microplastics (≤5 mm in diameter), are small granules that can be unintentionally released to the environment during manufacturing and transport. Because of their environmental persistence, they are widely distributed in the oceans and on beaches all over the world. They can act as a vector of potentially toxic organic compounds (e.g., polychlorinated biphenyls) and might consequently negatively affect marine organisms. Their possible impacts along the food chain are not yet well understood. In order to assess the hazards associated with the occurrence of plastic pellets in the marine environment, it is necessary to develop methodologies that allow for rapid determination of associated organic contaminant levels. The present protocol describes the different steps required for sampling resin pellets, analyzing adsorbed organochlorine pesticides (OCPs) and identifying the plastic type. The focus is on the extraction of OCPs from plastic pellets by means of a pressurized fluid extractor (PFE) and on the polymer chemical analysis applying Fourier Transform-InfraRed (FT-IR) spectroscopy. The developed methodology focuses on 11 OCPs and related compounds, including dichlorodiphenyltrichloroethane (DDT) and its two main metabolites, lindane and two production isomers, as well as the two biologically active isomers of technical endosulfan. This protocol constitutes a simple and rapid alternative to existing methodology for evaluating the concentration of organic contaminants adsorbed on plastic pieces.
Found in: ključnih besedah
Summary of found: ...polymer chemical analysis applying Fourier Transform-InfraRed (FT-IR) spectroscopy. The developed methodology focuses on 11 OCPs and...
Keywords: Environmental Sciences, Issue 125, Microplastics, resin pellets, pesticides, persistent organic pollutants, organochlorine pesticides, dichlorodiphenyltrichloroethane, endosulfan, hexachlorocyclohexane, lindane, Fourier transform infrared spectroscopy, pressurized fluid extractor
Published: 10.07.2017; Views: 2454; Downloads: 0

18.
Design of a highly photocatalytically active ZnO/CuWO4 nanocomposite
Matjaz Valant, Saim Emin, 2017, published scientific conference contribution abstract (invited lecture)

Abstract: We report the synthesis, photocatalytic activity and mechanistic study of a novel heterostructure (HTS) with an efficient charge separation. A ZnO/CuWO4 HTS material is reported for the first time. The nanocomposite (NC) consists of CuWO4 nanoparticles (ca. 200-400 nm) decorated with ZnO nanorods (ca. 30 nm, 100 nm length) and is shown to be a highly active photocatalyst for decomposition of model contaminants including methyl orange and terephthalic acid. The ZnO/CuWO4 interface is shown to be the key for controlling the enhanced activity of the composite material. Transient absorption spectroscopy studies demonstrated that a photoinduced charge transfer across the ZnO/CuWO4 interface increased electron-hole lifetime by 3 orders of magnitude, from < 20 s in ZnO to 30 ms in the ZnO/CuWO4 NC sample. Our findings show that through interface design efficient HTS materials can be prepared for a wide range of photocatalytic applications.
Found in: ključnih besedah
Summary of found: ...activity of the composite material. Transient absorption spectroscopy studies demonstrated that a photoinduced charge transfer...
Keywords: CuWO4, nanocomposite, transient absorption spectroscopy
Published: 28.08.2017; Views: 2837; Downloads: 0
.pdf Fulltext (621,87 KB)

19.
Atomic-level mechanisms of magnesium oxidation
Dmytro Orlov, Matjaž Valant, Sandra Gardonio, Mattia Fanetti, 2016, published scientific conference contribution

Abstract: Magnesium has been recently becoming an increasingly popular material for various applications. However, excessive chemical reactivity, and oxidation rate in particular, is a major obstruction on the way of Mg to become widely adopted. A significant problem causing the lack of Mg reactivity control is insufficient understanding of mechanisms involved in the oxidation of magnesium surface. Herewith we present the investigation of atomic-level mechanisms of oxidation initiation and propagation in pure Mg. Namely, X-ray photoelectron spectroscopy at synchrotron Elettra was used as a surface sensitive direct method to determine the valence of Mg and O and the valence band states at the early stage of oxide formation over a principal, most densely packed, crystallographic plane (0001) in pure Mg. The mechanisms of oxygen adsorption on magnesium free surface followed by oxidation (i.e. initiation and kinetics of MgO formation) are clarified. Copyright © 2016 by The Minerals, Metals & Materials Society. All rights reserved.
Found in: ključnih besedah
Summary of found: ...propagation in pure Mg. Namely, X-ray photoelectron spectroscopy at synchrotron Elettra was used as a...
Keywords: Magnesium, Oxidation, Synchrotron radiation, X-ray photoelectron spectroscopy
Published: 25.08.2017; Views: 2589; Downloads: 0
.pdf Fulltext (2,91 MB)

20.
Search done in 0 sec.
Back to top