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Chemical structure in Cu-modified TiO2-SiO2 nanocomposites calcined at 500 °C for 1 h in air
T. Čižmar, Iztok Arčon, Urška Lavrenčič Štangar, 2017, published scientific conference contribution abstract

Found in: osebi
Keywords: Cu-modified TiO2-SiO2 photocatalysts, titanium dioxide, metal doping, Cu K-edge XANES, EXAFS, photocatalytic activity
Published: 22.08.2017; Views: 11310; Downloads: 0
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Edge profiles in K shell photoabsorption spectra of gaseous hydrides of 3p elements and homologues
Giuliana Aquilanti, Alojz Kodre, Iztok Arčon, Robert Hauko, Jana Padežnik Gomilšek, original scientific article

Abstract: Photoabsorption spectra of gaseous hydrides of 3p elements (PH3, H2S, HCl) are measured in the energy region of photoexcitations pertaining to K edge. The analysis of the edge profile is extended to hydrides of 4p series (GeH4, AsH3, H2Se, HBr) from an earlier experiment, and to published spectra of 2p hydrides (CH4, NH3, H2O, HF) and noble gases Ar, Kr and Ne and SiH4. The edge profiles are modelled with a linear combination of lorentzian components, describing excitations to individual bound states and to continuum. Transition energies and probabilities are also calculated in the non-relativistic molecular model of the ORCA code, in good agreement with the experiment. Edge profiles in the heavier homologues are closely similar, the symmetry of the molecule governs the transitions to the lowest unoccupied orbitals. In 2p series the effect of the strong nuclear potential prevails. Transitions to higher, atomic-like levels remain very much the same as in free atoms.
Found in: osebi
Keywords: X-ray absorption spectra, gaseous hydrides, 3p K-edge spectra, DFT
Published: 23.08.2017; Views: 1287; Downloads: 0
.pdf Fulltext (703,57 KB)

Role of Surface Cu-O-Zr Sites in the Photocatalytic Activity of TiO2 Nanoscale Particles
Nataša Novak Tušar, Iztok Arčon, Urška Lavrenčič Štangar, Olena Pliekhova, 2016, published scientific conference contribution abstract

Found in: osebi
Keywords: Photocatalysis, Titanium dioxide, Copper, Zirconia, co-doping, EXAFS, XANES
Published: 23.08.2017; Views: 1822; Downloads: 0
.pdf Fulltext (426,28 KB)

Structural analysis of sunlight efficient Cu and Zr modified TiO2 photocatalyst
Olena Pliekhova, Iztok Arčon, Urška Lavrenčič Štangar, 2017, published scientific conference contribution abstract

Found in: osebi
Keywords: TiO2, photocatalysis, EXAFS, surface modification
Published: 23.08.2017; Views: 1616; Downloads: 0
.pdf Fulltext (577,74 KB)

Contribution of Cu and Zr to the Properties of TiO2 for Photocatalytic Water Treatment
Olena Pliekhova, Iztok Arčon, Nataša Novak Tušar, Urška Lavrenčič Štangar, 2017, published scientific conference contribution abstract

Found in: osebi
Keywords: Photocatalysis, water treatment, surface modification, durability
Published: 23.08.2017; Views: 1730; Downloads: 0
.pdf Fulltext (509,62 KB)

A Mechanistic Study of Magnesium Sulfur Batteries
Ana Robba, Alen Vižintin, Jan Bitenc, Gregor Mali, Iztok Arčon, Matjaž Kavčič, Matjaž Žitnik, Klemen Bučar, Giuliana Aquilanti, Charlotte Martineau-Corcos, Anna Randon-Vitanova, Robert Dominko, 2017, original scientific article

Abstract: Magnesium sulfur batteries are considered as attractive energy storage devices due to the abundance of electrochemically active materials and high theoretical energy density. Here we report the mechanism of a Mg-S battery operation, which was studied in the presence of simple and commercially available salts dissolved in a mixture of glymes. The electrolyte offers high sulfur conversion into MgS in the first discharge with low polarization. The electrochemical conversion of sulfur with magnesium proceeds through two well-defined plateaus, which correspond to the equilibrium between sulfur and polysulfides (high-voltage plateau) and polysulfides and MgS (low-voltage plateau). As shown by XANES, RIXS and NMR studies, the end discharge phase involves MgS with Mg atoms in a tetrahedral environment resembling the wurtzite structure, while chemically synthesized MgS crystalizes in the rock-salt structure with octahedral coordination of magnesium.
Found in: osebi
Keywords: magnesium, sulfur, rechargeable batteries, XAS, NMR
Published: 19.10.2017; Views: 1577; Downloads: 0
.pdf Fulltext (1,48 MB)

Surface modified titanium dioxide using transition metals
Andraž Šuligoj, Iztok Arčon, Matjaž Mazaj, Goran Dražić, Denis Arčon, Pegie Cool, Urška Lavrenčič Štangar, Nataša Novak Tušar, 2018, original scientific article

Abstract: Titanium dioxide has been widely used as an antimicrobial agent, UV-filter and catalyst for pollution abatement. Herein, surface modifications with selected transition metals (Me) over colloidal TiO2 nanoparticles and immobilization with a colloidal SiO2 binder as composite films (MeTiO2/SiO2) on a glass carrier were used to enhance solar-light photoactivity. Colloidal TiO2 nanoparticles were modified by loading selected transition metals (Me ¼ Mn, Fe, Co, Ni, Cu, and Zn) in the form of chlorides on their surface. They were present primarily as oxo-nanoclusters and a portion as metal oxides. The structural characteristics of bare TiO2 were preserved up to an optimal metal loading of 0.5 wt%. We have shown in situ that metal-oxo-nanoclusters with a redox potential close to that of O2/O2 were able to function as co-catalysts on the TiO2 surface which was excited by solar-light irradiation. The materials were tested for photocatalytic activity by two opposite methods; one detecting O2 (reduction, Rz ink test) while the other detecting OH (oxidation, terephthalic acid test). It was shown that the enhancement of the solar-light activity of TiO2 by the deposition of transition metal oxo-nanoclusters on the surface depends strongly on the combination of the reduction potential of such species and appropriate band positions of their oxides. The latter prevented excessive self-recombination of the photogenerated charge carriers by the nanoclusters in Ni and Zn modification, which was probably the case in other metal modifications. Overall, only Ni modification had a positive effect on solar photoactivity in both oxidation and reduction reactions.
Found in: osebi
Keywords: surface modified TiO2, XANES, EXAFS, Nickel, solar light photocatalyst
Published: 01.06.2018; Views: 925; Downloads: 0
.pdf Fulltext (1,24 MB)

Polysulfides formation in different electrolytes from the perspective of X-ray absorption spectroscopy
Robert Dominko, Alen Vižintin, Giuliana Aquilanti, Lorenzo Stievano, Maria Joseph Helen, Anji Reddy Munnangi, Maximilian Fichtner, Iztok Arčon, 2018, original scientific article

Abstract: Li-S batteries are promising energy storage technology for the future, however there two major problems remained which need to be solved before successful commercialization. Capacity fading due to polysulfide shuttle and corrosion of lithium metal are directly connected with the type and quantity of electrolyte used in the cells. Several recent works show dependence of the electrochemical behavior of Li-S batteries on type of the electrolyte. In this work we compare and discuss a discharge mechanism of sulfur conversion in three different electrolytes based on measurements with sulfur K-edge XAS. The sulfur conversion mechanism in the ether based electrolytes, the most studied type of solvents in the Li-S batteries, which are enabling high solubility of polysulfides are compared with the fluorinated ether based electrolytes with a reduced polysulfide solubility and in carbonate based electrolytes with the sulfur confined into a ultramicroporous carbon. In all three cases the sulfur reduction proceeds through polysulfide intermediate phases with a difference on the type polysulfides detected at different steps of discharge.
Found in: osebi
Keywords: Li-S batteries, operando sulphur K-edge XANES, EXAFS, Li-polysulphides
Published: 01.06.2018; Views: 1054; Downloads: 0
.pdf Fulltext (579,89 KB)

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