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61.
A Biogenerated Polymetallic Catalyst from Society's Wastes
Oreste Piccolo, Stefano Paganelli, Petro Zanatta, Sebastiano Tieuli, Laura Sperni, Franco Baldi, Iztok Arčon, Michele Gallo, Katarina Vogel-Mikuš, 2019, izvirni znanstveni članek

Opis: Aims:Preparation of the new metals - polymeric composite, Met x-EPS (I), to be used as a green catalyst in water or in two-phase aqueous conditions. Study Design: Recovery and valorization of polymetallic wastes to obtain directly new catalysts using a microorganism to explore their application in removal of difficult and dangerous chemical pollutants present in aqueous environment
Ključne besede: Metals - polymeric composite, biogenerated polymetallic exopolysaccharide, new catalyst from metallic wastes, hydrodechlorination of PCBs in water
Objavljeno v RUNG: 06.05.2019; Ogledov: 3267; Prenosov: 0
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62.
Alternative Recovery and Valorization of Metals from Exhausted Catalytic Converters in a New Smart Polymetallic Catalyst
Sebastiano Tieuli, Franco Baldi, Iztok Arčon, Katarina Vogel-Mikuš, Michele Gallo, Laura Sperni, Oreste Piccolo, Stefano Paganelli, 2019, izvirni znanstveni članek

Opis: A new metals-polymeric composite, Metx-EPS (I), was prepared to be used as catalyst in water or in two-phase aqueous conditions. The metals source was an exhausted catalytic converter that was grinded and treated with an acidic solution at room temperature. After filtration, the solution was concentrated, neutralized and added to a broth of Klebsiella oxytoca DSM 29614 to produce (I) where metals are embedded in a peculiar polysaccharide structure (EPS). The composite was easily recovered from the fermentation broth and purified. The process protocol was verified many times and was shown to be reproducible satisfactorily. The % recovery of metals, originally present in the converter, was good as determined by atomic absorption. The morphology and the chemical state of main metals in (I) were investigated by X-ray absorption spectroscopy methods (XANES and EXAFS). No metallic alloy seems to be evident. The catalytic activity and a possible synergic effect due to the presence of the different metals was valuated in the hydrogenation of some substrates, valuable precursors for theproduction of fine chemicals.
Ključne besede: Biogenerated polymetallic exopolysaccharide, biphasic catalysis, hydrogenation, metals-polymeric composite, new catalyst from metallic wastes, EXAFS, XANES
Objavljeno v RUNG: 06.05.2019; Ogledov: 3149; Prenosov: 0
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63.
Synthesis of a Cu/ZnO Nanocomposite by Electroless Plating for the Catalytic Conversion of CO2 to Methanol
Maja Pori, Iztok Arčon, Damjan Lašič Jurković, Marjan Marinšek, Goran Dražić, Blaž Likozar, Zorica Crnjak Orel, 2019, izvirni znanstveni članek

Opis: The process of methanol synthesis based on the hydrogenation of CO2 was investigated over binary Cu/ZnO catalyst materials, prepared by applying a novel electroless plating fabrication method. The activity of the produced catalytic samples was determined at temperature range between 200 and 300 °C and the feedstock conversion data were supplemented with a detailed microstructure analysis using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD) and Cu and Zn K-edge, X-ray absorption near-edge structure (XANES) measurements and extended X-ray absorption fine-structure (EXAFS) measurements. It was confirmed that the disorder in the Cu crystallites created unique geometrical situations, which acted as the additional reactive centres for the adsorption of the reactant molecule species. Copper and zinc structural synergy (spill-over) was also demonstrated as being crucial for the carbon dioxide’s activation. EXAFS and XANES results provide strong evidence for surface alloying between copper and zinc and thus the present results demonstrate new approach applicable for explaining metal–support interactions.
Ključne besede: EXAFS, CuZn alloy, Spillover mechanism, CO2 valorization, Electroless deposition method, Heterogeneous catalysis
Objavljeno v RUNG: 12.04.2019; Ogledov: 3506; Prenosov: 0
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64.
Unraveling the arrangement of Al and Fe within the framework explains the magnetism of mixed-metal MIL-100(Al,Fe)
Gregor Mali, Matjaž Mazaj, Iztok Arčon, Darko Hanžel, Denis Arčon, Zvonko Jagličić, 2019, izvirni znanstveni članek

Opis: Properties of mixed-metal MOFs depend on the distribution of different metals within their frameworks. Determination of this distribution is often very challenging. Using an example of aluminum- and iron-containing MIL-100, we demonstrate that 27Al NMR spectroscopy, when combined with first-principles calculations and magnetic, X-band electron paramagnetic resonance, Fe K-edge extended X-ray absorption fine structure, and Mössbauer measurements, enables one to accurately determine the arrangement of Al and Fe within the metal trimers, which are the basic building units of MIL-100. In this particular material, the incorporation of Fe and Al on the framework metal sites is random. Crucial for deciphering the arrangement is detecting NMR signals, shifted because of the strong hyperfine interaction between the 27Al nuclei and the unpaired electronic spins of Fe3+ ions, assigning the shifted signals aided by first-principles calculations of hyperfine couplings, and quantitatively evaluating the NMR intensities and the measured effective magnetic moment.
Ključne besede: Fe EXAFS, XANES, MIL100, MOF, magnetizem
Objavljeno v RUNG: 26.03.2019; Ogledov: 3155; Prenosov: 0
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65.
Cu and Zr surface sites in photocatalytic activity of TiO [sub] 2 nanoparticles : the effect of Zr distribution
Olena Pliekhova, O. L. Pliekhov, Mattia Fanetti, Iztok Arčon, Nataša Novak Tušar, Urška Lavrenčič Štangar, 2019, izvirni znanstveni članek

Opis: The present work is focused on the role of ZrO2 modification in the performance of CuO modified TiO2. Zirconia loading leads to formation of more resistant photocatalytic layers compared to samples modified with only copper containing species. Surface modification of mixed phase TiO2 with CuO/ZrO2 improves the degradation of Reactive blue 19 dye under simulated solar irradiation. An in-depth investigation of the catalysts showed that in case of CuO/ZrO2 modification, the covering of the TiO2 surface with zirconium containing species prevents morphological and harmful energetic changes induced by copper species formed on the rutile TiO2 phase at a higher copper loading.
Ključne besede: titanium dioxide, surface modification, XAS analysis, surface acidity, Hammett indicators
Objavljeno v RUNG: 26.03.2019; Ogledov: 3120; Prenosov: 0
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ESUO: The European Synchrotron and FEL User Organisation: Aims & Activities
Iztok Arčon, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: The European Synchrotron and free-electron laser (FEL) User Organisation (ESUO) established in 2010 [1] today represents about 30.000 users. We aim at representing the users from all European countries. Each country is represented within ESUO by one up to four national delegate(s), depending on the size of the user community in the respective country. ESUO’s main objectives are (i) to promote an integrated approach throughout Europe for the use of European synchrotron and FEL facilities, (ii) to enable all European scientists to make use of the existing European synchrotron and FEL research infrastructures, solely based on scientific merit of their submitted proposals for beamtime requests, and this independently from the financial situation of the user (country), (iii) to facilitate open transnational access to European light sources through programmes of the European Union, (iv) to disseminate information about scientific opportunities and funding mechanisms for access to synchrotron and FEL facilities, and (v) to be a discussion and acting partner regarding the coordination of the synchrotron and FEL user activities within Europe. In the past few years, ESUO has contributed to several joint activities in the frame of successfully completed European FP7 projects such as ELISA (March 2009 - August 2011) and CALIPSO (June 2012 - May 2015). Some past ESUO activities concern, amongst others:  the user representation in e.g. the CALIPSO and BioStruct-X European projects by ESUO delegates;  the contribution to the CALIPSOplus project application;  the dissemination of ESUO activities by means of e.g. poster presentations and talks delivered at international conferences, specialized user meetings/workshops, and;  several initiatives which have been attended to promote transnational access activities [3] and to favor the continuation of transnational user access to national facilities in Europe within the new European Framework Program Horizon 2020 [4]. Today, chance is given to ESUO to keep constructively acting for the users in the frame of joint networking activities being part of the HORIZON 2020 project CALIPSOplus [5] (May 2017 – April 2021, Grant Agreement No 730872) coordinated by Helmholtz-Zentrum Dresden-Rossendorf (HZDR). In the framework of CALIPSOplus, ESUO is contributing to project networking activities which are, amongst others, shown in the present contribution. With the aim to further prepare the future science at European synchrotron and FEL user facilities, ESUO is contributing to the League of European Accelerator-based Photon Sources (LEAPS) initiative [6].
Ključne besede: European synchrotron user organisation, Transnational access, FEL, CALIPSO
Objavljeno v RUNG: 01.10.2018; Ogledov: 3378; Prenosov: 0
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69.
Kako lahko z različnimi vrstami svetlobo opazujemo očem nevidni svet okoli nas
Iztok Arčon, vabljeno predavanje na konferenci brez natisa

Opis: Svetloba nam v vsakdanjem žvljenju omogoča, da vidimo in spoznavamo svet okoli nas. Kako zelo je svetloba pomembna za naše življenje opazimo še posebej, če se za nekaj časa znajdemo v popolni temi. In vendar predstavlja vidna svetloba, ki jo lahko zaznajo naše oči, le droben delček v širokem spektru razlčnih vrst svetlobe, ki nam jih ponuja narava. V predavanju si bomo ogledali, kako lahko s svetlobo različnih valovnih dolžin, od infrardeče, preko vidne, ultravijolične in rentgenske svetlobe, opazujemo očem nevidni svet okoli nas. Spomnili se bomo tudi nekaj velikih znastvenih odkritji o svetlobi v zadnjih dvesto letih. Ta osnovna odkritja o lastnostih svetlobe so nam odprla pogled neposredno v svet atomov in danes omogočajo razvoj sodobnih merskih tehnologij na atomski skali. Brez njih si skoraj ne znamo večpredstavljati razvoja novih tehnološko zanimivih materialov in različnih nanotehnologij in različnih raziskav onesnaženja okolja na atomskem nivoju.
Ključne besede: rentgesnka svetloba, UV, IR, slikanje, mikroskopiranje, rentgenska absorpcijska spektroskopija
Objavljeno v RUNG: 01.10.2018; Ogledov: 3384; Prenosov: 0
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70.
Sulfur based batteries studied by in-operando S K-edge RIXS and XAS spectroscopy
Matjaž Kavčič, Ana Robba, Janez Bitenc, Alen Vižintin, Iztok Arčon, Matjaž Žitnik, Klemen Bučar, Robert Dominko, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Sulfur based batteries are considered as very attractive energy storage devices. Sulfur is one of the most abundant elements in the earth, it is electrochemically active material which can accept up to two electrons per atom. In combination with alkali metals, sulfur forms electrochemical couples with much higher theoretical energy density compared to Li-ion batteries commonly available today. At the moment, the electrochemical couple with Li is most extensively studied. While the main principle of operation is known the relevant operation mechanism(s) is not completely clear. Even more promising is the electrochemical couple with Mg providing almost twofold higher volumetric energy density due to its ability to provide two electrons during oxidation. However, Mg-S batteries are still in the very early stage of research and development and the complex mechanism of sulfur conversion has been less extensively studied. In order to improve the understanding of sulfur electrochemical conversion and its interactions within electrode, we need to apply new experimental approaches capable to provide precise information about local environment of S in the cathode during battery operation. In our work, resonant inelastic X-ray scattering (RIXS) and XAS measurements at the sulfur K-edge performed in operando mode were used to study the lithium-polysulfide formation during the discharge process. Measurements were performed at ID26 beamline of the ESRF synchrotron using tender X-ray emission spectrometer [1]. Resonant excitation condition enhanced the sensitivity for the lithium−polysulfide detection. On the other hand, the sulfate signal from the electrolyte was heavily suppressed and the self-absorption effects minimized due to fixed excitation energy. This experimental methodology was used to provide quantitative analysis of sulfur compounds in the cathode of a Li−S battery cell during the discharge process [2]. The high-voltage plateau in the discharge curve was characterized by a rapid conversion of solid sulfur into liquid phase Li polysulfides reaching its maximum at the end of this plateau. At this point the starting point for the precipitation of the Li2S from the liquid polysulfide phase was observed. The same approach has been used also for the Mg-S battery revealing similar mechanism as in case of Li-S battery [3]. The electrochemical conversion of sulfur with magnesium proceeds through two well-defined plateaus, which correspond to the equilibrium between sulfur and Mg polysulfides (high-voltage plateau) and polysulfides and MgS (low-voltage plateau).
Ključne besede: Mg-Sulphur batteries, XANES, RIXS
Objavljeno v RUNG: 13.09.2018; Ogledov: 4381; Prenosov: 0
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