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Nanostructures for advanced plasmonic applications
Kejík, Lukáš ; Brzobohatý,, Oto (referee) ; Dostálek,, Jakub (referee) ; Šikola, Tomáš (advisor)
Plazmonika, charakterizovaná spojením oscilací volných elektronů v kovech s elektromagnetickými vlnami, se dostala do popředí s pokroky v nanotechnologiích. Tato synergie vede k pozoruhodným vlastnostem objektů v nanoměřítku, vyznačujících se lokalizovaným a zesíleným elektromagnetickým polem. Tyto vlastnosti umožňují širokou škálu aplikací nanostruktur, zahrnujících biodetekci, zesilování emise, získávání solární energie a náhrazování optických komponent. Tato dizertační práce je zaměřena na aplikace plazmonických nanostruktur, primárně na plošné optické komponenty známé jako metapovrchy. Kromě toho zkoumá jejich použití ve fotokatalytických aplikacích, využívajících energetické horké nosiče náboje generované prostřednictvím plazmoniky. Dizertační práce začíná úvodem do teoretických základů plazmoniky, zdůrazněním klíčových parametrů řídících plazmonické vlastnosti a přehledem jejích nejpřesvědčivějších aplikací. Následně obsahuje čtyři experimentální části, které ukazují využití plazmonických nanostruktur pro různé účely, včetně ovládání fáze světla, dynamických metapovrchů, zkoumání efektů vnitřní krystalinity a využití horkých nosičů náboje ve fotoelektrochemických systémech. Tyto studie spojuje využití pokročilých nebo méně konvenčních materiálů, jako je oxid vanadičný nebo dichalkogenidy přechodných kovů, v oblasti plazmoniky a nanotechnologií.
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Thick-film sensors for heavy metals detection
Gajdoš, Libor ; Majzlíková, Petra (referee) ; Prášek, Jan (advisor)
This project describes the possibilities of heavy metals detections in solutions using differential pulse voltammetry with tree-electrode electrochemical thick-film sensors. In the theoretical part, the thick-film technology is described as well as thick-film pastes’ types and compositions, followed by introduction to electrochemistry and electro-analytical methods of measurement. This project also describes the three measured heavy metals – cadmium, lead and copper. In the practical part, heavy metals’ ions detection in solutions using carbon working electrode and determination of the detection limit and sensitivity are described and discussed. Finally the evaluation of obtained results and results comparison to hygienic limits are included.
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Reactivity and controll of properties of metallic materials
Tkacz, Jakub ; Šoukal, František (referee) ; Zmrzlý, Martin (advisor)
This thesis is focused on corrosion protection of magnesium alloys AZ 91. Very important is material corrosion in some environments and last but not least surface treatment as grinding, polishing and etching. Theoretical part of this thesis is about magnesium and magnesium alloy. It focuses on properties, in order to determine the best procedure for corrosion protection. It characterize material corrosion- for example corrosion in special environment (atmosphere, water, etc.) or elektrolyte corrosion. Big part of theoretical part is focused on electrochemistry, in particular kinetic aspects (Tafel diagrams, corrosion current, etc.) and potentiostatic testing, where are observed properties of material in relation to potential: corrosion potential Ecorr, brakedown potential Ebd and repassivation potential Erp. This work present preparing, utilization and positive or negative aspects of corrosion protection. Metallography is important too since metallographical preparation is crucial for the research on the material. Described metallography procedures are mounting, grinding, polishing, etching and interpretation. Experimental part of this thesis is in particular about corrosion properties of magnesium alloy AZ 91. It focuses on calculation of corrosion rate in defferent environments. Principle is mass defekt of the alloy. The environments are: destilled water, hot service water and 3% NaCl solution (like sea water). Last but not least are important. procedure manipulation with materials. Very important are choice and composition of solutions, etching time, choice of polishing cloth, lubricant solution and good pressure. Beacuse of this aspects can be show corrosion action of environments on magnesium alloy AZ 91 by photographies.
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Observation of lead electrode surface by atomic force microscope AFM
Bouška, Marek ; Máca, Josef (referee) ; Bača, Petr (advisor)
This master's thesis is focused on in situ observation of the negative electrode of the lead acid accumulator using atomic force microscopy AFM. Discussed topics are lead acid accumulator, atomic force microscopy, cyclic voltammetry and current knowledge of the in situ observation of the lead acid accumulator using AFM. The main task of this project is assembling the experimental cells, make in situ observation of the negative electrode surface of the lead acid accumulator. In the end evaluate if this method is suitable for the lead acid battery observation.
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Plasmonically active electrochemical electrodes based on tungsten disulfide nanotubes decorated with gold nanoparticles
Salajková, Zita ; Daňhel,, Aleš (referee) ; Ligmajer, Filip (advisor)
When an electromagnetic wave illuminates metal nanostructure under right circumstances, it can couple to the motion of electrons and thus give rise to so-called LSPR. When these collective oscillations non-radiatively decay, they excite charge carriers that can have, for a short moment of time, highly non-thermal energy distribution. These so-called "hot" electrons and holes can then take part in photochemical applications, e.g. in reactions on photoactive electrodes where hot electrons act as catalysts. Gold nanoparticles seem to be a good candidate for fabrication of such electrodes because they exhibit resonantly enhanced absorption due to plasmon excitation in the visible and near infrared spectral range, which could make the solar energy harvesting more efficient. In this work we present electrohemical experiments that should help to clarify the underlying principles of photochemical reactions involving hot electrons. Our model system consists of indium tin oxide electrodes covered with tungsten disulphide nanotubes that were previously decorated by gold nanoparticles. By comparing the results of chronoamperometric measurements on individual components of this system it was shown that excitation of plasmonic nanoparticles indeed leads to photocurrents and that electrochemical methods can serve as a valuable tool for analysis of photochemical reactions catalyzed by hot electrons.
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Optimization of electrochemical sensor for detection in microvolume
Gajdoš, Libor ; Pekárek, Jan (referee) ; Prášek, Jan (advisor)
This thesis describes optimization and modification of standard thick-film electrochemical sensor to be able to be used for detection in microvolumes. In the theoretical part, the thick film technology is described. The work is then focused on the wettability of surfaces followed by introduction to electrochemistry and electro-analytical methods. In the experimental part, screen-printing of various types of thick film pastes on ceramic substrates for determination of their wettability and the following modification of the sensors with thick-film paste and with Parylene vaporization can be found, as well as the basic electrochemical measurements in microvolume using the modified sensor. Finally the results are summarized in conclusion.
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Application of metal and semiconductor nanostructures for biodetection
Kejík, Lukáš ; Skládal, Petr (referee) ; Kolíbal, Miroslav (advisor)
The master’s thesis deals with two applications of gold discoidal nanostructures exhibiting plasmon resonance for biodetection. The first approach considers the detection of changes in the phase on plasmonic antennas using coherence-controlled holography microscope. It was found that the steepness of the phase is increasing with the illumination wavelength when plasmon resonance is excited in larger antennas. The sensitivity of the phase to refractive-index changes of the surrounding media was observed when the largest response was given by antennas in resonance with wavelength of illumination. Next part deals with plasmon resonance detection by means of optical spectroscopy combined with voltametry which characterizes the electrochemical activity. Changes in resonance wavelength induced by the presence of SSC buffer were observed, although this influence seems to diminish in time. Conducted experiments have also shown that oxygen-plasma cleaning is not suitable for sample surface cleaning because of oxidation of metals including gold as well.
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Development and characterization of micro-reference electrodes for bioelectronics applications
Florian, Vojtěch ; Glowacki, Eric Daniel (referee) ; Ehlich, Jiří (advisor)
The subject of this work was the construction and long term stability measurement of micro-reference electrodes based on anodized silver wire and titanium wire with Ag/AgCl paste. A measuring apparatus, with which the long term stability was measured, was constructed as a part of this work. These days, commercial reference electrodes are available on the market. These reference electrodes are characterized by their excellent long term stability, however, they are too large and too expensive to be used in bioelectronic systems. Because of this, the science community has been trying to miniaturize reference electrodes in the past years. Without reference electrodes, it is impossible to do most electrochemical measurements. Based on the long term stability of measured samples it was determined which of the samples meet the criteria for bioelectronic measurements. It was also determined which of the studied samples were most suitable. The last result of this work is a measuring apparatus that can measure the long term stability of up to thirty-two electrodes.
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Electrode Active Materials for Lithium-Ion Accumulators
Čech, Ondřej ; Oriňáková, Renáta (referee) ; Paidar,, Martin (referee) ; Sedlaříková, Marie (advisor)
This doctoral thesis deals with synthesis and characterisation of electroactive electrode materials for li-ion batteries and accumulators. The work is divided into two main parts. One deals with LiFePO4 based cathode composite electroactive material and in the second is described the synthesis and utilization of monoclinic TiO2(B) as an anode for li-ion cell. The main aim of the work is to relate the synthesis procedure and structural properties of both materials to its electrochemical preformance.
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