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Efficient de-agglomeration of polysilane macromolecules in solution and their molecular size
Matjaž Valant, Mattia Fanetti, Artem V. Badasyan, Andraž Mavrič, 2017, published scientific conference contribution abstract

Found in: osebi
Keywords: polysilane, solubility, de-agglomeration, dynamic light scattering
Published: 03.07.2017; Views: 1778; Downloads: 0
.pdf Fulltext (1,81 MB)

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: osebi
Keywords: Magnesium, Oxidation, Synchrotron radiation, X-ray photoelectron spectroscopy
Published: 25.08.2017; Views: 1634; Downloads: 0
.pdf Fulltext (2,91 MB)

High-temperature stabilization of bulk amorphous Al2O3
Andraž Mavrič, Matjaž Valant, Gregor Mali, Mattia Fanetti, 2018, original scientific article

Abstract: We present a method for high temperature stabilization of bulk amorphous aluminium oxide. The stabilization is achieved by dispersing polysilane dendritic molecules in aluminium hydroxide gel, which upon thermal treatment gives amorphous aluminium oxide stable up to 900 °C. The dispersed macromolecules covalently bind to the alumina matrix and induce homogeneously distributed strain fields that keep the alumina amorphous. The thermal conversion of the precursor system was followed by thermogravimetry with an evolved gas analysis, infrared spectroscopy and 29Si NMR. The amorphous structure of aluminium oxide was confirmed with an X-ray and electron diffraction. Additionally, the amorphous state was supported by presence of penta-coordinated aluminium detected by 27Al NMR and a low bandgap measured by a UV–visible absorption spectroscopy.
Found in: osebi
Keywords: Amorphous aluminium oxide, Polysilane, Nanocomposite, Stabilization
Published: 30.07.2018; Views: 1538; Downloads: 0
.pdf Fulltext (2,67 MB)

Effects of Different Copper Loadings on the Photocatalytic Activity of TiO2-SiO2 Prepared at a Low Temperature for the Oxidation of Organic Pollutants in Water
T. Čižmar, Iztok Arčon, Mattia Fanetti, Urška Lavrenčič Štangar, 2018, original scientific article

Abstract: The objective of this research is to examine how Cu modification can improve the photocatalytic activity of TiO2-SiO2, to explainthe correlation between the Cu concentration and the chemical state of Cu cations in the TiO2-SiO2 matrix, and the photocatalytic activity under UV/solar irradiation. The Cu-modified TiO2-SiO2 photocatalysts were prepared by a low-temperature sol–gel method from organic Cu, Si and Ti precursors with various Cu concentrations (0.05–3 mol %). The sol–gels were dried at 150 8C to obtain the photocatalysts in a powder form. The photocatalytic activity was determined by using a fluorescence- based method of terephthalic acid decomposition. An up to three times increase in photocatalytic activity is obtained if the TiO2-SiO2 matrix is modified with Cu in a narrow concentration range from 0.05 to 0.1 mol%. At higher Cu loadings, the photocatalytic activity of the Cu-modified photocatalysts is lower than that of the un-modified reference TiO2-SiO2 photocatalyst. XRD was used to show that all Cu-modified TiO2-SiO2 composites with different Cu concentrations have the same crystalline structure as un-modified TiO2-SiO2 composites. The addition of Cu does not change the relative ratio between the anatase and brookite phases or unit cell parameters of the two TiO2 crystalline structures. We used Cu K-edge X-ray absorption near edge structure and extended X-ray absorption fine structure analyses to determine the valence state and local structure of Cu cations in the Cu-modified TiO2-SiO2 photocatalysts. The results elucidate the mechanism responsible for the improved photocatalytic activity. In samples with a low Cu content, which exhibit the highest activity, Cu@O@Ti connections are formed, which suggests that the activity enhancement is caused by the attachment of CuII cations on the surface of the photocatalytically active TiO2 nanoparticles, so CuII cations may act as free-electron traps, which reduce the intensity of recombination between electrons and holes at the TiO2 photocatalyst surface. At higher Cu loadings no additional Cu@O@Ti connections are formed, instead only Cu@O@Cu connections are established. This indicates the formation of amorphous or nanocrystalline copper oxide, which hinders the photocatalytic activity of TiO2.
Found in: osebi
Keywords: Cu modified TiO2-SiO2 photocatalyst Cu EXAFS, XANES, Organic pollutants
Published: 30.08.2018; Views: 899; Downloads: 0
.pdf Fulltext (1,53 MB)

Hydrothermal synthesis of Bi [sub] 2 Se [sub] 3 platelets
Blaž Belec, Sandra Gardonio, Mattia Fanetti, Matjaž Valant, 2018, published scientific conference contribution abstract

Found in: osebi
Published: 12.09.2018; Views: 753; Downloads: 0
.pdf Fulltext (2,10 MB)

The effect of Zr loading on photocatalytic activity of Cu modified TiO [sub] 2
Urška Lavrenčič Štangar, Nataša Novak Tušar, Iztok Arčon, Mattia Fanetti, O. L. Pliekhov, Olena Pliekhova, 2018, published scientific conference contribution abstract

Found in: osebi
Keywords: Cu Zr modified TiO2, EXAFS, XANES
Published: 12.09.2018; Views: 784; Downloads: 0
.pdf Fulltext (990,75 KB)

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