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Study of the effect of thin film catalyst morphology on efficiency of water electrolyzer with proton conducting membrane
Hrbek, Tomáš ; Matolín, Vladimír (advisor) ; Nováková, Jaroslava (referee)
Title: Study of the effect of thin film catalyst morphology on efficiency of water electrolyzer with proton conducting membrane Author: Tomáš Hrbek Department: Department of Surface and Plasma Science Supervisor: prof. RNDr. Vladimír Matolín, DrSc., Department of Surface and Plasma Science Abstract: This bachelor thesis deals with the possibility of reducing the amount of noble metals in catalytic layers of proton exchange water electrolyzer (PEM-WE). The PEM-WE is an important unit of hydrogen economy as it allows storage of excess energy from renewable sources in the form of chemical energy. In the first part, etched membrane electrolyzers were prepared and tested, membrane etching is a previously unpublished procedure leading to a reduction of the amount of catalyst. Etched membranes were studied by scanning electron microscopy and, consequently tested in real working conditions in electrolyzers. In the second part of the work; Ir and IrO2 were compared as catalysts for PEM-WE anode. Their in-cell performance was tested directly in the electrolysers and in controlled condition by rotating disk electrode. Keywords: electrolyzer, magnetron sputtering, thin-layer catalyst, etched mem- brane PEM, Ir vs. IrO2
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Deposition of Nanocomposite Thin Films
Kratochvíl, Jiří ; Kylián, Ondřej (advisor)
Nanocomposite thin films can find application in photovoltaics, optics, fabrication of sensors, or in biomedicine. This work investigates fabrication and characterization of thin metal-plasma polymer nanocomposite films which have direct application because of their unique optical properties (e.g. SERS - Surface-Enhanced Raman Spectroscopy) or antibacterial effects (biomedicine). We fabricated metal nanoparticles either by magnetron sputtering (island growth) or by means of gas aggregation source of nanoparticles, thereby we got nanoparticles with very different morphologies. We used silver as a material for nanoparticles because of its antibacterial effects. We incorporated these nanoparticles into sputtered Nylon and sputtered PTFE (polytetrafluoroethylene) plasma polymer matrix. These two polymers have very different chemical structure and related different surface energy. First, we compared growth of nanoparticles on substrates of sputtered Nylon and PTFE. Then we compared properties of sandwich nanocomposites polymer-Ag-polymer for both types of nanoparticles and for both matrix materials. We characterized produced thin films especially with respect to their stability in water (antibacterial films), thermal stability (sterilization by heating) and stability on the open air (storage). Finally, the tests...
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Controllable synthesis, treatment and characterization of anodes for Direct Formic Acid Fuell Cell
Bieloshapka, Igor ; Jiříček, Petr (advisor) ; Khalakhan, Ivan (referee) ; Čechal, Jan (referee)
Title: Controllable synthesis, treatment and characterization of anodes for Direct Formic Acid Fuell Cell Author: Mgr. Igor Bieloshapka Department/Institute: Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University Supervisor of the doctoral thesis: Ing. Petr Jiříček, CSc., Institute of Physics of the Czech Academy of Sciences, Division of Solid State Physics, Department of Optical Materials Abstract: At this doctoral thesis, anodes were prepared by novel DC magnetron sputtering technique for direct formic acid fuel cells (DFAFCs). Anode part consisted of support material and catalyst. Carbon cloth and polyaniline were used as a support. Palladium and palladium-copper bimetallic catalysts were deposited on the top of the support. Scanning electron microscope (SEM) and atomic force microscope (AFM) were used for investigation of the morphology of the anodes. Composition and chemical states on the anode part were studied by x-ray photoelectron spectroscopy (XPS). Transmission electron microscope (TEM) together with the XPS technique were used for characterizing graphene oxide (GO) and reduced graphene oxide (RGO) as a promising support for the polymer membrane fuel cells. For decreasing the role of substoichiometric PdCx phase and other contaminations on the surface of...
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Epitaxial growth and characterization of metamagnetic nanoparticles for biomedical applications
Motyčková, Lucie ; Gröger,, Roman (referee) ; Arregi Uribeetxebarria, Jon Ander (advisor)
Magnetické nanočástice představují perspektivní prostředek pro široké množství biomedicínských aplikací v neustále se rozvíjejících oblastech diagnostiky a léčebné terapie. Využití magnetických nanočástic z metamagnetických materiálů by mohlo poskytnout výrazný přínos například z hlediska zlepšení ovladatelnosti biologických subjektů uvnitř lidského těla. Tato práce se zabývá růstovými mechanismy a magnetickými vlastnostmi nanočástic ze slitiny železa s rhodiem (FeRh) ukotvených na substrátu MgO. Slitina FeRh byla vybrána pro její specifickou fázovou přeměnu z antiferomagnetické do feromagnetické fáze nastávající v blízkosti pokojové teploty, což umožňuje ovládání magnetických vlastností nanočástic v teplotním rozsahu blízkém lidskému tělu. Prezentované nanostruktury jsou vyráběny magnetronovým naprašováním využívajícím přístup samouspořádání “bottom–up”. Morfologie a magnetické chování připravených nanostruktur jsou vyšetřovány pomocí mikroskopie atomových a magnetických sil, které umožňují získat prostorové rozložení feromagnetických a antiferomagnetických domén v jednotlivých nanoostrůvcích.
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Vývoj, optimalizace a validace analytické metody na stanovení antibiotika ciprofloxacin ve vodě pomocí LC/MS
VACLOVÁ, Jana
This bachelor thesis deals with the development, optimization and validation of an analytical method for determination of antibiotic ciprofloxacin in water using LC/MS. At first, the development and optimization of the analytical method was performed. The following parameters were selected for optimization: mobile phase composition and injection volume of sample, conditions of electrospray, voltage on S-lens and F-lens, collision energy, maximum trap fill time and number of microscans. Then, the analytical method was successfully validated. Finally, the method was applied for the determination of the antibiotic ciprofloxacin in the layers made from PEEK.
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Deposition of ultrathin films on polymers
Libenská, Hana ; Hanuš, Jan (advisor) ; Kousal, Jaroslav (referee)
Thin metal films deposited on the polymer substrates are of fundamental importance for the formation of conductive structures on the surfaces of the polymers. In the case of discontinuous layers of silver or copper, so-called anomalous absorption occurs in the visible range of the spectrum. This phenomenon can be used to create different sensors, eg. based on surface enhanced Raman spectroscopy. In this work, the deposition of discontinuous Ag and Cu layers on PEEK and PET polymer foils and glass and polished silicon was used studied. The magnetron sputtering was chosen for deposition at very low pressure and the effect of pressure on the growth of these films was investigated. It was found that at a pressure of 0.2 Pa the copper layers on the two polymers grew almost smooth, while the island structure appeared at a pressure 1.2 Pa. In the case of Ag deposition, the island structure of the layer appeared already at a pressure of 0.2 Pa, and differences in the growth of the Ag films in dependence of the the substrate were observed.
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Study of 3-phase catalytic layers for polymer electrolyte fuel cells and electrolysers
Fuka, Šimon ; Matolínová, Iva (advisor) ; Khalakhan, Ivan (referee)
Title: Study of 3-phase catalytic layers for polymer electrolyte fuel cells and electrolysers Author: Šimon Fuka Department: Department of Surface and Plasma Science Supervisor: doc. Mgr. Iva Matolínová, Dr., Department of Surface and Plasma Science Abstract: The diploma thesis focuses on the study of catalytic layers for Proton Exchange Membrane Fuel Cells (PEMFC) or electrolyzers based on the mixture of platinum and cerium oxide. These layers are prepared by using magnetron sputtering, their properties are studied depending on the deposition parameters or the choice of the substrate by using SEM, AFM, XPS and then tested as an anode in the fuel cell. In addition to the morphology of the catalytic layers, it has been shown that the dispersion of very small nanoparticles of the catalyst with a size of 1-2 nm has a great effect on PEMFC performance. Most of the prepared samples gave maximal and maximal specific performance much higher than the state of art values published for Pt-CeOx system. By studying properties of the layers used as the anode catalysts, this work contributes to the understanding of PEMFC fuel cell behavior and, consequently, to its potential commercialization. Keywords: Fuel cell, cerium oxide, platinum, catalyst, magnetron sputtering
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Study of thin film catalysts for direct methanol fuel cell anode
Fusek, Lukáš ; Matolín, Vladimír (advisor) ; Nováková, Jaroslava (referee)
This thesis is focused on the study of catalyst layers for direct methanol fuel cell anode prepared by a new method using magnetron sputtering. Homemade as well as commercial supports were used. The study of properties of prepared layers was carried out in fuel cell using methods of electrochemical analysis, such as electrochemical impedance spectroscopy and cyclic voltametry for examination of conductivity, catalyst activity and resistance to poisoning by residual carbon species. Polarization curves were used to investigate power and diffusion properties. A reference cell composed of commercially-available electrodes was chosen for comparison.
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Electron microscopy study of nanostructured thin film catalysts for micro-fuel cell application
Lavková, Jaroslava ; Matolínová, Iva (advisor) ; Ruterana, Pierre (referee) ; Šubrt, Jan (referee)
Present doctoral thesis is focused on electron microscopy and spectroscopy investigation of novel metal-oxide anode catalyst for fuel cell application. Catalyst based on Pt- doped cerium oxide in form of thin layers prepared by simultaneous magnetron sputtering deposition on intermediate carbonaceous films grown on silicon substrate has been studied. The influence of catalyst support composition (a-C and CNx films), deposition time of CeOx layer and other deposition parameters, as deposition rate, composition of working atmosphere and Pt concentration on the morphology of Pt-CeOx layers has been investigated mainly by Transmission Electron Microscopy (TEM). The obtained results have shown that by suitable preparation conditions combination we are able to tune final morphology and composition of catalyst. Composition of carbonaceous films and Pt-CeOx layers was examined by complementary spectroscopy techniques - Energy Dispersive X-ray Spectroscopy (EDX), Electron Energy Loss Spectroscopy (EELS) and X-ray Photoelectron Spectroscopy (XPS). Such prepared porous structures of Pt-CeOx are of promising as anode catalytic material for real fuel cell application. Keywords: cerium oxide, platinum, fuel cell, magnetron sputtering, Transmission Electron Microscopy
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Low Platinum Content Thin Film Catalysts for Hydrogen Proton Exchange Membrane Fuel Cells
Václavů, Michal ; Matolín, Vladimír (advisor) ; Bystroň, Tomáš (referee) ; Neitzel, Armin (referee)
Novel type of catalyst for proton exchange membrane fuel cells anode is demonstrated. It is based on magnetron sputtered Pt-CeO2 a Pt-Sn-CeO2 mixed oxides. It is shown, that these materials allow to significantly decrease amount of platinum in the anode catalyst. The preparation method yields high amount of platinum in ionized form, especially Pt2+ , which is related to the high activity. Stability of these catalytic layers were investigated under conditions similar to fuel cell anode (humidified hydrogen at elevated temperature). Also interaction of hydrogen a water under UHV conditions were studied, demonstrating high stability of the Pt2+ species. In the last part of the work sputtered Pt-Co mixed catalyst were investigated to be used in the PEMFC cathode. It is demonstrated that at right conditions, the sputtered alloy catalyst improves mass activity on cathode by factor more than two.
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