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Fotokatalitska razgradnja reaktivnega barvila reactive blue 19 s TiO[sub]2, dopiranim s cirkonijem in bakrom
Chris Černe, Tomaž Gravnar, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: reaktivno barvilo, RB 19, titanov dioksid, doping, metoda sežiganja raztopin
Objavljeno v RUNG: 02.03.2022; Ogledov: 1097; Prenosov: 6
URL Povezava na celotno besedilo
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Role of Surface Cu-O-Zr Sites in the Photocatalytic Activity of TiO2 Nanoscale Particles
Olena Pliekhova, Iztok Arčon, Nataša Novak Tušar, Urška Lavrenčič Štangar, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: Photocatalysis, Titanium dioxide, Copper, Zirconia, co-doping, EXAFS, XANES
Objavljeno v RUNG: 23.08.2017; Ogledov: 4130; Prenosov: 0
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Correlations between photocatalytic activity and chemical structure of Cu-modified TiO2–SiO2 nanoparticle composites
T. Čižmar, Urška Lavrenčič Štangar, Iztok Arčon, 2016, izvirni znanstveni članek

Opis: Copper-modified TiO2–SiO2photocatalysts were prepared by sol–gel method based on organic copper,silicon and titanium precursors. Copper concentration varied from 0.1 to 3.0 mol%. A widely appliedmodel reaction of photocatalytic oxidation of terephtalic acid (TPA) in water solution was used in order toevaluate the catalytic activities of elaborated samples. The crystal structures of the titania components ofall tested titania–silica species were studied using XRD analysis. The influence of Cu2+cation incorporationon the crystal structure of titania, as well as the chemical states and the neighbouring structures of coppercations, have been examined by means of Cu K-edge EXAFS and XANES analysis. The experimental datashow that there is a ten times increase in photocatalytic activity when TiO2–SiO2matrix is modified with0.1 mol% of Cu. It can be supposed that an enhancement of photocatalytic activity of low-concentratedcopper-modified titania–silica nanocomposites is probably due to a close attachment of Cu2+cationsto the surfaces of photocatalytically active TiO2nanoparticles. In this case, Cu2+cations may possiblyact as free electron traps reducing the intensity of recombination between opposite free charge carriers(electrons, holes) available at the photocatalyst’s surface.
Ključne besede: Cu-modified TiO2–SiO2photocatalysts, Titanium dioxide, Metal doping, Cu K-edge XANES, EXAFS, Photocatalytic activitya
Objavljeno v RUNG: 17.01.2017; Ogledov: 4719; Prenosov: 0
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Donor doping of K0.5Na0.5NbO3 ceramics with strontium and its implications to grain size, phase composition and crystal structure
Jitka Hreščak, Goran Dražić, Marco Deluca, Iztok Arčon, Alojz Kodre, M. Dapiaggi, Tadej Rojac, Barbara Malič, Andreja Benčan, 2017, izvirni znanstveni članek

Opis: In this study, the particular effects of A-site donor doping in a lead-free piezoceramic material K0.5Na0.5NbO3 (KNN) doped with Sr2+, i.e., the crystal-structure change, the secondary-phase formation and the grain-size decrease, were investigated. The already-reported causes of these effects upon doping KNN were critically discussed and a mechanism of the effects’ formation was suggested and experimentally supported with advanced analytical methods. Extended X-ray absorption fine structure (EXAFS) analyses proved that the Sr occupies the perovskite A-sublattice, and locally modifies the KNN monoclinic structure to cubic. With the help of Sr K-edge EXAFS and wavelength-dispersive X-ray spectroscopy, the Sr was found to be homogenously distributed in the KNN perovskite lattice with 0.5, 1 and 2% Sr and no Sr segregation on the nano level was found in any of the studied samples with transmission electron microscopy. Introducing Sr into the A-sublattice, as well as accounting for the charge-compensating A-site vacancies in the starting composition, causes increasing lattice disorder and microstrain, as determined from a Rietveld refinement of the synchrotron X-ray diffraction data. Above 2% Sr the system segregates the A-site vacancies in a secondary phase in order to release the chemical pressure, as revealed by Raman spectroscopy. All these effects result in an increasing number of low-angle grain boundaries that limit the grain growth and finally lead to a significant grain-size decrease.
Ključne besede: perovskite, potassium sodium niobate, donor doping, cation vacancies
Objavljeno v RUNG: 17.01.2017; Ogledov: 4372; Prenosov: 312
.pdf Celotno besedilo (2,11 MB)

Photocatalytic Activity of Zirconium- and Manganese- Codoped Titania in Aqueous Media: The Role of the Metal Dopant and its Incorporation Site
O. L. Pliekhov, Iztok Arčon, Nataša Novak Tušar, Urška Lavrenčič Štangar, 2016, izvirni znanstveni članek

Opis: 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.
Ključne besede: doping, manganese, oxidation, X-ray absorption spectroscopy, zirconium
Objavljeno v RUNG: 21.07.2016; Ogledov: 3748; Prenosov: 0
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Correlations between photocatalytic activity and chemical structure in copper doped TiO2-SiO2 with surface/incorporated Cu2+ sites
Tihana Čižmar, Iztok Arčon, Urška Lavrenčič Štangar, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Sol−gel method was used to synthesize copper doped TiO2-SiO2 with varied dopant concentrations using tetraisopropoxide (TTIP) and copper acetlyacetonate (CuAcAc) as titania and copper sources. Structural information of Cu cation incorporation and its chemical state in the coatings are determined with Cu K-edge EXAFS and XANES analysis. The correlations between chemical state of the Cu dopant and the photocatalytic properties of the new active coatings are discussed.
Ključne besede: dip-coating, titanium dioxide, metal doping, Cu K-edge XANES, photocatalytic activity
Objavljeno v RUNG: 07.07.2016; Ogledov: 5146; Prenosov: 0

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