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Photocatalytic properties of hybrid titania-silica layers
Sekerová, Kateřina ; Drbohlavová, Jana (referee) ; Dzik, Petr (advisor)
This diploma thesis is focused on the preparation of hybrid titania-silica layers. Titanium tetraisopropoxide and tetraethyl orthosilicate with Levasil were used as the precursors for TiO2 and SiO2 synthesis, respectively. The layers were deposited on substrates by material printing. Furthermore, this work is focused on the study of the rheological properties of TiO2-SiO2 sol and characterization of prepared films by XRD, SEM, ellipsometry, AFM, pencil hardnes test, optical microscopy. Optical properties were also characterized by transmitance and reflectance measurement and the functionality of these layers was demonstrated by a stearic acid degradation experiment.
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Studies towards the Preparation of Organic-Inorganic Hybrid Silica Fibers via Electrospinning
Koukolová, Anna ; Dzik, Petr (referee) ; Hüsing, Nicola (advisor)
Polyorganosilany spadají do skupiny hybridních materiálů třídy II, které nabízejí nové možnosti materiálových funkcí a jejich vlastností. Ačkoliv byly v této kategorii již některé materiály zkoumány a stejně tak i jejich aplikace, nebyly doposud vlákna na základě polyorganosilanu v mikro a nano rozměru popsány což bylo motivací pro tuto práci. Předkládaná diplomová práce se zabývá podrobným zkoumáním poly(vinylmethyldimethoxysilanu) jako možného prekurzoru pro elektrostatické zvlákňování. Za účelem přípravy polymeru na bázi vinylmethylsilanu byla provedena radikálová polymerace a podmínky reakce byly modifikovány se záměrem změny molekulové hmotnosti získaného polymeru. Stupeň polymerace byl upravován na základě změny koncentrace iniciátoru a byl stanovován dynamickým rozptylem světla v roztoku polymeru a spektroskopickou metodou nukleární magnetické rezonance. Elektrostatické zvlákňování je velkou měrou spojeno s vlastnostmi roztoku a důraz byl proto kladen právě na zjištění těchto vlastností. Na základě experimentů bylo zjištěno, že syntetizovaný polymer je na přípravu vláken vhodný. Nicméně byly získány i fragmenty vláken a to s využitím polymeru v roztoku methanolu. Předpokladem zvlákňování je dostatek propojení mezi polymerními řetězci. Tento přístup byl studován se zapojením sol-gel postupu a bylo zjištěno, že fáze sol-gel procesu je velmi významná s ohledem na tvorbu vláken. Dalším využitým postupem pro získání vláken bylo začlenění dalšího polymeru do směsi jako nosiče a tímto postupem byla získána vlákna s různým průměrem.
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Study of titanium dioxide photocatalytic activity by fluorescence spectroscopy
Blašková, Martina ; Vala, Martin (referee) ; Dzik, Petr (advisor)
This thesis deals with principles and methodology of evaluation of photocatalytic activity of titanium dioxide by fluorescence detection of hydroxyterephthalic acid and assessment of use this method in batch reactor. To the fluorescence study of activity we used hydroxyterephthalic acid as a primary product of oxidation terephthalic acid as a solution or in the form of immobilized layers. In the liquid phase we monitored fluorescence of hydroxyterephthalic acid by using a conventional fluorimeter and fiber spectrometer. In the solid state we monitored fluorescence of hydroxyterephthalic acid by spectrofluorometer with holder of solid samples.
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Tungsten trioxide coatings fabricated from nanocrystalline suspension and binder
Filipská, Markéta ; Zlámal,, Martin (referee) ; Dzik, Petr (advisor)
This diploma thesis deals with layers of tungsten oxide, which are prepared from a nanoparticle suspension and a binder. The coating composition consisted in the first case of ground tungsten oxide nanoparticles alone, then of acetylated peroxotungstic acid alone and finally of a mixture of ground tungsten oxide mixed with acetylated peroxotungstic acid. The compositions thus formed were applied to conductive FTO glass and thus act as photoanodes. A stainless steel needle is used as a counter electrode for volt-ampere measurements. The work focuses on the study of physicochemical properties of prepared photoanodes and their optimalization in order to obtain the highest possible values of generated photocurrents. The electrical properties of all cells were determined using voltammetric characteristics.
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Printed transparent oxide conductors
Bartoš, Radim ; Pekárková, Jana (referee) ; Dzik, Petr (advisor)
Thin films of tin oxide doped by fluorine or antimony were prepared by spincoating technique and material printing technique. Plenty of inorganic and organic coumpouds were used as precursors of fluorine and antimony. Sheet resistence of films were measured by 4-probe method and film thickness were determined by contact profilometer. Films were analyzed by Xray diffraction (XRD) and scan electron microscopy (SEM).
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Electroassisted photocatalysis
Filipská, Markéta ; Pekárková, Jana (referee) ; Dzik, Petr (advisor)
This thesis is focused on fotoelectrochemical cells, where as photocathode is used titanium dioxide coated on conductive FTO glass and as counter electrode is used gold electrode. Thesis is also focused on relationship between intensity of irradiation and Faradaic efficiency and also influence of the overvoltage to the rate of degradation od the model pollutant, in this case Acid Orange 7. Electrical properties were measured by recording values of photocurrent. The aim of this thesis was to study influence material composition of photoanode and connection with intensity of irradiation, rate of degradation proces of model pollutant and current.
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Synthesis and properties of tungsten tioxide layers fabricated by the sol-gel process
Hesková, Helena ; Pekárková, Jana (referee) ; Dzik, Petr (advisor)
This work deals with the optimization of the preparation process of WO3 layers by the sol-gel method and their properties. Several precursor solutions were prepared which were applied to the substrate by spin-coating and drop-casting. The deposited layers were annealed at 450°C until complete degradation of the polymer matrix contained in the precursor. The structure of the layers was observed by scanning electron microscopy, their composition by the X-ray diffraction and their thickness was determined by profilometry. The properties of the prepared layers were also investigated by photoelectrochemical measurements.
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Optimalization of gel electrolyte for printed UV sensor based on photoelectrochemical cell
Vrbková, Kateřina ; Gemeiner,, Pavol (referee) ; Dzik, Petr (advisor)
This paper deals with the construction of photoelectrochemical cell, used for detection of ultraviolet radiation as a UV sensor. Photoelectrochemical cell consists of three layers, layer of photoactive semiconductor titanium dioxide, carbon electrodes and poly(vinyl alcohol) polymer electrolyte. The sensor layer enables the detection of UV radiation with the subsequent generation of photocurrent. Material printing techniques, such as screenprinting, pad printing and inkjet printing were used to produce the cell. Gel electrolyte was characterized by optical microscopy and rheometry. Sensor functionality was verified by use of electroanalytical techniques.
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Titanium Dioxide for Photovotaics
Zbořilová, Zdeňka ; Ing. Dvonka Vladimír,Ph.D. (referee) ; Dzik, Petr (advisor)
This bachelor thesis deals with the utilization of titanium dioxide for photovoltaics. The theoretical part gives a brief outline on the properties, methods of preparation and utilization of titanium dioxide mesoporous thin films for solar cells (dye sensitized solar cells and hybrid ones). The practical part includes a preparation of dye sensitized solar cells and a basic study on their behaviour during light exposure.
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Modification of inks for luminescent panels
Foldynová, Klára ; Dzik, Petr (referee) ; Vala, Martin (advisor)
This bachelor thesis deals with the study of the influence of luminescent additives on the features of printed electroluminescent elements. The goal of the thesis is to find a strategy for expanding the color spectrum of these elements while maintaining their functionality. An important step was the addition of additive to the basic luminescent layer of ZnS and its influence on emission of radiation. A change of color spectrum was proved by usage the U111 fluorophore and in particular the wavelength change and the intensity of the radiation on the input voltage and frequency were observed. The obtained results can be used in further studies to extend the knowledge of electroluminescence.
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