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* old and bolonia study programme


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Novel two-step vapor-phase synthesis of UV – Vis light active Fe2O3/WO3 nanocomposites for phenol degradation
Urška Lavrenčič Štangar, Olena Pliekhova, Mariangela Brisotto, Elza Bontempi, Cinzia Sada, Chiara Maccato, Alberto Gasparotto, Giorgio Carraro, Davide Barreca, 2016, original scientific article

Abstract: Supported Fe2O3/WO3 nanocomposites were fabricated by an original vapor phase approach, involving the chemical vapor deposition (CVD) of Fe2O3 on Ti sheets and the subsequent radio frequency (RF)-sputtering of WO3. Particular attention was dedicated to the control of the W/Fe ratio, in order to tailor the composition of the resulting materials. The target systems were analyzed by the joint use of complementary techniques, that is, X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDXS), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and optical absorption spectroscopy. The results showed the uniform decoration of α-Fe2O3 (hematite) globular particles by tiny WO3 aggregates, whose content could be controlled by modulations of the sole sputtering time. The photocatalytic degradation of phenol in the liquid phase was selected as a test reaction for a preliminary investigation of the system behavior in wastewater treatment applications. The system activity under both UVand Vis light illumination may open doors for further material optimization in view of real-world end-uses.
Found in: ključnih besedah
Keywords: Fe2O3, WO3, Nanocomposites, Chemical vapor deposition, Sputtering, Photocatalysis
Published: 03.08.2016; Views: 2478; Downloads: 0
.pdf Fulltext (1,91 MB)

Design of a highly photocatalytically active ZnO/CuWO4 nanocomposite
MATJAŽ VALANT, 2016, original scientific article

Found in: ključnih besedah
Summary of found: ... Photocatalysis Heterostructure Nanocomposite Methyl orange Terephthalic acid...
Keywords: Photocatalysis Heterostructure Nanocomposite Methyl orange Terephthalic acid
Published: 08.09.2016; Views: 2219; Downloads: 0
.pdf Fulltext (1,63 MB)

Reuse of TiO2-based catalyst for solar driven water treatment; thermal and chemical reactivation
Urška Lavrenčič Štangar, Dominik Kosir, Hrvoje Kušić, Marin Kovacic, Subhan Salaeh, Dionysios D. Dionysiou, Ana Lončarić Božić, 2017, original scientific article

Found in: ključnih besedah
Summary of found: ...Solar photocatalysis, TiO2-FeZ, Thermal and chemical reactivation, Ozone, Diclofenac...
Keywords: Solar photocatalysis, TiO2-FeZ, Thermal and chemical reactivation, Ozone, Diclofenac
Published: 03.11.2016; Views: 2301; Downloads: 0
.pdf Fulltext (3,57 MB)

Ikram Muhammad, master's thesis

Found in: ključnih besedah
Summary of found: ...vode, degradacija, ki onesnažuje, organska predhodniki, TiO2 photocatalysis, fotokatalitsko aktivnost, Zr in Cu dopantov, superoksid...
Keywords: odpadne vode, degradacija, ki onesnažuje, organska predhodniki, TiO2 photocatalysis, fotokatalitsko aktivnost, Zr in Cu dopantov, superoksid anioni, hidroksilni radikal, metilen modro
Published: 06.02.2017; Views: 2597; Downloads: 178
.pdf Fulltext (2,94 MB)

Ana Veternik, 2017, master's thesis

Abstract: Since water is an essential substance for all life on earth, it is therefore vital to prevent its pollution and to improve wastewater purification processes. There is a vast number of pollutants which can contaminate water, of which bisphenol A (known as an endocrine disruptor) is the pollutant studied herein. In this study, several TiO2/GO based nanocomposites with various GO loadings (2, 4, 10, 20 and 40%) and differently shaped nanocrystalline TiO2 phases (titanate nanotubes (TNTs) and calcined titanate nanotubes (TNTs_500)) were synthesised. All of the nanocomposites were characterised through SEM, UV-vis-DR, TGA, BET, FT-IR and CHNS analyses and were used in the heterogeneous photocatalytic degradation of bisphenol A and compared to the activity of pure TNTs and TNT_500 photocatalysts. All TiO2/GO nanocomposites exhibit much better activity than pure TNTs and TNTs_500 catalysts. The conversion of the BPA was analysed using HPLC and the mineralisation was analysed using a TOC analysis. The best experiment was performed with TNTs_500 + 10% GO composite, which can be attributed to the TiO2 crystalline structure obtained. According to the results obtained, TiO2 + 10% GO was found to exhibit the best degradation ratio, which can be ascribed to the fact that excessive GO can act as a charge carrier recombination centre and promotes the recombination of electron-hole pairs in reduced GO.
Found in: ključnih besedah
Summary of found: ...heterogeneous photocatalysis, titanium dioxide, graphene oxide, bisphenol A...
Keywords: heterogeneous photocatalysis, titanium dioxide, graphene oxide, bisphenol A
Published: 23.02.2017; Views: 2665; Downloads: 214
.pdf Fulltext (2,96 MB)

Transparent titania-zirconia-silica thin films for self-cleaning and photocatalytic applications
Urška Lavrenčič Štangar, Vlasta Brezova, Nives Vodišek, Kandalam Ramanujachary, 2017, published scientific conference contribution

Found in: ključnih besedah
Summary of found: ...TiO2, ZrO2, thin films, photocatalysis, mechanical stability...
Keywords: TiO2, ZrO2, thin films, photocatalysis, mechanical stability
Published: 13.03.2017; Views: 2383; Downloads: 5
.pdf Fulltext (1,46 MB)

Transparent titania-zirconia thin films for self-cleaning and photocatalytic application
Vlasta Brezová, Kandalam Ramanujachary, Nives Vodišek, Urška Lavrenčič Štangar, 2016, published scientific conference contribution abstract

Abstract: Thin films were prepared by sol-gel process, where different amount of zirconia were added to titania. Photocatalytic activity of thin films was measured by two methods i) determination of degradation ration of methyl stearate with measuring the contact angle and ii) formation of hydroxyterephthalic acid was measured by spectrofluorometer. Prepared samples were characterized by UV-Vis spectrophotometer, SEM, XRD, FT-IR ATR, and BET. The result of measurements of photocatalytic activity shows that the highest activity has a sample without addition of zirconia, but mechanical stability of that sample is worse.
Found in: ključnih besedah
Summary of found: ... photocatalysis, ZrO2/ TiO2, thin films, self-cleaning, low-temperature, sol-gel...
Keywords: photocatalysis, ZrO2/ TiO2, thin films, self-cleaning, low-temperature, sol-gel process
Published: 14.03.2017; Views: 2379; Downloads: 130
.pdf Fulltext (462,52 KB)

Synthesis and characterization of metal/semiconductor nanocomposites for photocatalysis
Tina Mavrič, doctoral dissertation

Abstract: The doctoral dissertation focused on improving photocatalytic activity of nanopowdered ZnO by constructing I) Metal-Semiconductor and II) Semiconductor-Semiconductor heterostructures. Both heterostructure types have been reported to have a beneficial effect on photocatalytic efficiency. For the first part (I) Ag/ZnO nanocomposite was synthesized. Here we investigated an influence of polyvinylpyrrolidone (PVP) addition during the synthesis on the particle properties and their photoactivity. The second part (II) describes procedure development of ZnO based semiconductor-semiconductor composite that resulted in synthesis of highly efficient ZnO/CuWO4 composite. Ag/ZnO nanocomposite was synthesized from precursors in ethylene glycol (EG) in a hydrothermal reactor at 180 °C for 3h. No further thermal treatment was required after the synthesis since all samples showed good crystallinity. Silver precursor loading was 2.7 wt%, because this amount has shown the best photoactivity in preliminary sample testings. Two separate batches of Ag/ZnO nanopowders were prepared, one with addition of PVP, one without (labelled Ag/ZnO and Ag/ZnO*, respectively). All powders were in nanometer range, TEM images showed a major difference between the samples with and without PVP. While Ag nanoparticles were deposited uniformly over ZnO, Ag/ZnO* exhibited a substantial agglomeration of Ag. The photocatalytic efficiency was assessed under UV-Vis light. Ag/ZnO reached complete decolourization of 10–5 M methyl orange (MO) already in 80 min after the beginning of irradiation. The calculated degradation rate constant (k) for the Ag/ZnO was almost 2-times larger than for TiO2 P25 and 4-times larger than for ZnO. Ag/ZnO* also showed higher activity than pure ZnO*, but was inferior to Ag/ZnO (1.6-times of Ag/ZnO*). A reusability test performed on Ag/ZnO showed an excellent photoactivity of reused powders; second and third cycle exhibited higher photoactivity than the first cycle. The supreme photocatalytic activity of Ag/ZnO was also confirmed by degradation of terephthalic acid. To develop an efficient semiconductor-semiconductor heterostructure we have synthesized a combination of several materials with ZnO. We performed preliminary photocatalytic tests in order to assess the functionality of these heterostructures. The tested systems were the following: ZnO/MWCNT, ZnO/GO, ZnO/SiC, ZnO/Co3O4, ZnO/AgVO3. The synthesis of heterostructures was done via hydrothermal synthesis. The commercial or synthesized powers were dispersed together with the ZnO precursor in EG medium (180 °C/3h). The aim was to obtain higher photoactivity than that of pure ZnO. None of these systems was able to outperform pure ZnO. ZnO/CuWO4 system has, however, significantly improved ZnO photoactivity. Several synthesis routes were investigated, including the influence of different structure directing agents (PVP, CTAB, starch). The best performing system was obtained by separate hydrothermal synthesis of ZnO and CuWO4 in water with PVP. XRD analysis confirmed that to obtain the crystalline CuWO4 thermal treatment (500 °C) is needed. The heterostructure was also synthesized in ethanolic solution. ZnO particles were in a nanometer range, CuWO4 were larger and ranged from 200 to 400 nm. CuWO4 has successfully decreased the charge recombination in ZnO, which was confirmed by transient absorption spectroscopy studies. The photocatalytic activity was assessed for both MO and TPA (10–4 M) degradation. The ZnO/CuWO4 composite has completely decolourized the dye in 60 min of UV-Vis irradiation. k for ZnO/CuWO4 was ~2.5-times larger than that of ZnO. A 3-cycle reusability test with MO showed a small decrease in efficiency in the last cycle. TPA degradation has revealed lower efficiency for ZnO/CuWO4 in air but high efficiency in O2 and N2 atmosphere, where it reached 90% and 55% degradation rate, respectively.
Found in: ključnih besedah
Keywords: photocatalysis, zinc oxide, heterostructures, powders, Ag/ZnO composites, ZnO/CuWO4 composites
Published: 31.05.2017; Views: 3230; Downloads: 216
.pdf Fulltext (4,11 MB)

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