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53. Pogovor o avtorski pogodbi na SKS : okrogla miza v Cankarjevem domu, 28. novembra 2019Barbara Pregelj, Mateja Seliškar Kenda, Iztok Ilc, Nataša Detič, Vlasta Vičič, 2019, scientific film, scientific sound or video publication Abstract: Povezava do posnetka: https://www.youtube.com/watch?v=fTnxL9peFZc&ab_channel=Dru%C5%A1tvoslovenskihkni%C5%BEevnihprevajalcev Keywords: avtorska pogodba, prevajanje, tipska avtorska pogodba, DSKP, JAK, Združenje založnikov Published in RUNG: 21.09.2020; Views: 2125; Downloads: 0 This document has many files! More... |
54. Effect of Na, Cs and Ca on propylene epoxidation selectivity over CuOx/SiO2 catalysts studied by catalytic tests, in-situ XAS and DFTJanvit Teržan, Matej Huš, Iztok Arčon, Blaž Likozar, Petar Djinović, 2020, original scientific article Abstract: This research focuses on epoxidation of propylene over pristine, Na, Ca and Cs modified
CuOx/SiO2 catalysts using O2. The selectivity of the reaction is analyzed using a combination
of catalytic tests, in-situ XAS and DFT calculations. The initially present subnanometer CuO
clusters are present in all catalysts which re-disperse/flatten during reaction. During catalytic
reaction, the Cu1+ becomes the predominant oxidation state. There is no correlation between
propylene oxide (PO) selectivity and copper oxidation state. DFT analysis of the propylene
reaction pathway revealed that Na, Cs, and Ca addition decreases the bonding strength of
propylene to CuO and decreases the O2 activation barrier, while simultaneously increase the
exothermicity of O2 dissociation. The Na induced Cu-O bond modification decreases the
activation barrier from 0.87 to 0.71 eV for the oxametallacycle (OMC) ring closure (first step
in the reaction pathway favoring selectivity towards PO) compared to pristine 5Cu catalyst.
At the same time, we observed an increase (from 0.45 to 0.72 eV) of the barrier for the
abstraction of allylic hydrogen. The opposite effect is achieved by Ca addition: the activation
barrier for OMC ring closure increases to 1.08 eV and that for allylic hydrogen stripping
decreases to 0.16 eV. Keywords: Alkali modification, propylene epoxidation, reaction mechanism, copper oxide, activation barrier. Published in RUNG: 05.06.2020; Views: 2932; Downloads: 0 This document has many files! More... |
55. Ceramic synthesis of disordered lithium rich oxyfluoride materialsJean-Marcel Ateba Mba, Iztok Arčon, Gregor Mali, Elena Tchernychova, Ralf Witte, Robert Kruk, Miran Gaberšček, Robert Dominko, 2020, original scientific article Abstract: Disordered lithium-rich transition metal oxyfluorides with a general formula Li1þxMO2Fx (M being a transition
metal) are gaining more attention due to their high specific capacity which can be delivered from the facecentered
cubic (fcc) structure. The most common synthesis procedure involves use of mechanosynthesis. In
this work, ceramic synthesis of lithium rich iron oxyfluoride and lithium rich titanium oxyfluoride are reported.
Two ceramic synthesis routes are developed each leading to the different level of doping with Li and F and
different levels of cationic disorder in the structure. Three different Li1þxMO2Fx samples (x ¼ 0.25, 0.3 and 1) are
compared with a sample prepared by mechanochemical synthesis and non-doped LiFeO2 with fcc structure. The
obtained lithium rich iron oxyfluoride are characterized by use of M€ossbauer spectroscopy, X-ray absorption
spectroscopy, NMR and TEM. Successful incorporation of Li and F have been confirmed and specific capacity that
can be obtained from the samples is in the correlation with the level of disorder introduced with doping,
nevertheless oxidation state of iron in all samples is very similar. Conclusions obtained from lithium rich iron
oxyfluoride are validated by lithium rich titanium oxyfluoride. Keywords: Lithium batteries
Face centered-cubic
Oxyfluoride
Li-rich
Disorder Published in RUNG: 05.06.2020; Views: 4621; Downloads: 0 This document has many files! More... |
56. Study of water adsorption on EDTA dealuminated zeolite YO. L. Pliekhov, Olena Pliekhova, Iztok Arčon, Federica Bondino, Elena Magnano, Gregor Mali, Nataša Zabukovec Logar, 2020, original scientific article Abstract: Zeolite Y was synthesized and modified with EDTA dealumination procedure. The modified zeolites were
analyzed by X-ray diffraction, X-ray absorption spectroscopy, chemical analysis and water adsorption measurements.
We demonstrated that dealumination with bulk organic acid such as EDTA is able to reduce the
original intense water affinity. Furthermore, it was found that dealumination with EDTA, in contrast with
steaming and HCl dealumination, provides fully controllable, predictable and secure process of Al removal from
the zeolites’ frameworks. The shift of the adsorption isotherm in the low partial pressure range represents an
interesting result for adsorption-based applications. Keywords: Zeolite Y
Water sorption
Dealumination
Al XANES
EDTA treatment Published in RUNG: 05.06.2020; Views: 3188; Downloads: 0 This document has many files! More... |
57. SnO2-Containing Clinoptilolite as a Composite Photocatalyst for Dyes Removal fromWastewater under Solar LightAndraž Šuligoj, Jelena Pavlovič, Iztok Arčon, Nevenka Rajić, Nataša Novak Tušar, 2020, original scientific article Abstract: Due to their adsorbent, ion exchange and catalytic properties zeolites are suitable for a variety of applications. We report on the photocatalytic activity of a readily available and inexpensive natural zeolite clinoptilolite (Z) containing SnO2 (Sn-Z). The Sn-Z samples with 3–15 wt. % of Sn were prepared by using a precipitation–deposition method. Powder X-ray diffraction analysis showed that the zeolite structure was unaffected by the introduction of the Sn-phase. Diffuse reflectance UV/VIS spectra of the Sn-Z samples confirmed the presence of SnO2 and X-Ray absorption spectroscopy analyses suggested that the SnO2 particles mainly resided on the surface of the clinoptilolite, while ATR-FTIR analysis gave some clues that part of the SnO2 phase was incorporated in the pores of the zeolite. The presence of SnO2 in Sn-Z increased both adsorption capacity and photocatalytic performance which could be partially explained by higher surface area and partially with an increased negative potential of the surface. Adsorption and total degradation of methylene blue (MB) for the Sn-Z with the highest amount of Sn (15 wt.%) was about 30% and 45%, respectively, suggesting a synergetic effect between SnO2 and the clinoptilolite lattice. Reusability tests showed that these catalysts present a promising material for water purification. Keywords: SnO2, zeolite, SnO2-clinoptilolite composite, photocatalysis, solar light, methylene blue
removal, wastewater treatment Published in RUNG: 25.02.2020; Views: 3174; Downloads: 133 Full text (3,50 MB) |
58. Effects of a Mixed O/F Ligand in the Tavorite-Type LiVPO4O StructureSorour Semsari Parapari, Jean-Marcel Ateba Mba, Elena Tchernychova, Gregor Mali, Iztok Arčon, Gregor Kapun, Mehmet Ali Gülgün, Robert Dominko, 2020, original scientific article Abstract: We report the synthesis and detailed structural
and chemical characterization including electrochemical
properties of a lithium vanadium oxy/fluoro-phosphate
material. To the best of our knowledge, we have for the first
time synthesized a LiVPO4O-type phase with a mixed O/F
ligand. In the synthesis procedure, the LiVPO4O precursor
compound was fluorinated via LiF incorporation, with
preservation of the LiVPO4O framework structure. The
operating potential of the synthesized material is increased
compared to that of the LiVPO4O precursor (4.12 V vs 3.95 V
versus metallic lithium, respectively). The related increase in
operating potential was assigned to the effect of the
intermixing O/F ligand, which is attained via the successful
fluorine incorporation into the LiVPO4O structure. A characterization of the investigated materials was performed using
microscale-covering XRD, XANES, and NMR techniques as well as nanoscale spatially resolved imaging and analytical STEM
techniques. The obtained oxy/fluoro-phosphate phase is isostructural to LiVPO4O; however, the presence of the mixed O/F
ligand promoted a higher symmetry of vanadium octahedra. These variations of the vanadium local environment along with the
observed inhomogeneous distribution of the incorporated fluorine gave rise to the minor local deviations in vanadium valence.
Our results clearly emphasize the connection among the fluorine ligand incorporation, its local distribution, and the
electrochemical properties of the material. Keywords: LiVPO4O, XRD, SEM, V XANES, Tavorite-Type, electrochemical properties Published in RUNG: 17.02.2020; Views: 3070; Downloads: 0 This document has many files! More... |
59. Improved photocatalytic activity of anatase-rutile nanocomposites induced by low-temperature sol-gel Sn-modification of TiO2Ksenija Maver, Iztok Arčon, Urška Lavrenčič Štangar, Mattia Fanetti, Saim Emin, Matjaž Valant, 2020, original scientific article Abstract: The Sn-modified TiO2 photocatalysts are prepared by low-temperature sol-gel processing based on organic titanium
and tin precursors with varied Sn concentrations (from 0.1–20 mol .%). The role of Sn dopant as the
promotor of the formation of TiO2 rutile crystalline phase is explained and the optimal Sn concentration for
preparation of efficient Sn-modified titania photocatalyst is determined. Up to 40 % increase in photocatalytic
activity is achieved in Sn-modified TiO2 photocatalytic thin films dried at 150 °C with low Sn concentrations in
the range from 0.1 to 1 mol .%. At low Sn concentrations optimal ratio between anatase and rutile (nano)crystals
is obtained, which facilitates charge separation at the TiO2 photocatalyst’s surface. When the concentration of Sn
increases above 5 mol.% or when the films are calcined at 500 °C, the relative amount of rutile phase with
inferior photocatalytic activity, increases and the nanocrystals of titania grow, leading to fewer active sites per
unit mass and the reduction of activity in comparison to unmodified TiO2. Keywords: Anatase-rutile
Sn-modified TiO2
XAS analysis
Photocatalytic activity Published in RUNG: 10.02.2020; Views: 3176; Downloads: 0 This document has many files! More... |
60. X-ray absorption spectroscopy set-up for unstable gases: A study of 5p HydridesRobert Hauko, Jana Padežnik Gomilšek, Alojz Kodre, Iztok Arčon, 2020, original scientific article Abstract: An absorption cell is constructed for x-ray absorption spectroscopy of reactive, unstable or hazardous gases at
room temperature. In conjunction with in-situ micro-synthesis technique relying on handling the gas in syringes
it enabled a first measurement of x-ray absorption spectra in the region of K and L edges for the series of hydrides
of 5p elements (SnH4, SbH3, TeH2, HI). The signal-to-noise ratio above 103 was achieved, whereby fine detail is
discerned in the spectra, in particular the small sharp features above each absorption edge, testifying of coexcitations
of outer electrons in the core photoeffect. Keywords: X-ray absorption spectroscopy
Micro-synthesis absorption cell
Gaseous hydrides
Multielectron photoexcitations Published in RUNG: 10.02.2020; Views: 3692; Downloads: 0 This document has many files! More... |