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Preparation and Characterization of Porous Cerium Oxide/Carbon Bilayers on Silion Substrates
Dubau, Martin ; Matolínová, Iva (advisor) ; Jiříček, Petr (referee) ; Píš, Igor (referee)
This doctoral thesis concerns the preparation of porous cerium oxide/carbon bilayers on silicon substrates. In this regard, carbonaceous films in the form of amorphous carbon (a-C) and nitrogenated amorphous carbon (CNx) are considered. The influence of various process parameters of the cerium oxide deposition on the morphology of the final cerium oxide/carbon bilayer is investigated. A correlation could be found between the morphol- ogy of the bilayer and the stoichiometry of the cerium oxide film determined by means of XPS. Furthermore, a study regarding the chemical composition of the used carbonaceous films by means of various spectroscopic techniques is presented. It was found that the chemical composition of the carbonaceous films strongly depends on the deposition con- ditions of these films and influences the behaviour of these films during oxygen plasma treatment and cerium oxide deposition, respectively. 1
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Study of deposition of catalytic materials into fuel channels of micro-fuel cells on a chip
Chlupová, Šárka ; Matolínová, Iva (advisor) ; Grym, Jan (referee)
This diploma thesis is interested in usage of Electron Beam lithography process as an instrument of transport of contacts and catalytic layers to micro-channels of the micro monolithic planar fuel cell. Experimental part includes optimization of the PMMA resist deposition method on the 3D topography - spray coating - is performed with alternative spray coating system. The optimal spin speed resist, molecular weight and concentration is chosen during the optimization. Parameters of the exposition, developing and lift-off are also modified and three EBL processes are performed. The first ensures deposition of Au contacts to the channels; the second is for application of Pt layer to the cathode channel and the last aimed to cover the anode channel with CeO/CNx layer. All layers are deposited by magnetron sputtering.
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Investigation of membrane electrode assembly (MEA) for fuel cells
Fuka, Šimon ; Matolínová, Iva (advisor) ; Vorokhta, Mykhailo (referee)
Title: Investigation of membrane electrode assembly (MEA) for fuel cells Author: Šimon Fuka Department: Department of surface and plasma science Supervisor: doc. Mgr. Iva Matolínová, Dr., Department of surface and plasma science Abstract: This bachelor thesis is focused on the study of degradation of the fuel cell, specifically on the study of the catalyst diffusion into the membrane and of the chemical and morphological changes at the interface. The catalyst is prepared by magnetron sputtering directly on the membrane. Morphological changes at the interface will be monitored either by scanning electron microscope (SEM) or by using the focused ion beam (FIB). Diffusion of the catalyst will be observed using energy-dispersive X-ray spectroscopy (EDX). The bachelor thesis will contribute to the lifetime of the fuel cell type PEMFC (proton exchange membrane fuel cell). Keywords: Catalyst, Diffusion, Membrane, Fuel cell, SEM
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Novel nanocatalysts for fuel cells II: micro-fuel cells on chip
Onderková, Kristýna ; Matolínová, Iva (advisor) ; Johánek, Viktor (referee)
Title: Novel nanocatalysts for fuel cells II: micro-fuel cells on chip Author: Kristýna Onderková Department: Department of Surface and Plasma Science Supervisor: Doc. RNDr. Iva Matolínová, Dr., Department of Surface and Plasma Science Abstract: The thesis examines layers of cerium oxide doped with platinum, prepared by magnetron sputtering on various types of planar substrates. The work focuses primarily on how the layers are affected by doping different amounts of platinum. The samples were studied mainly using Scanning Electron Microscopy (SEM). Using the combination of SEM and Focused Ion Beam (FIB), we have prepared thin samples (lamellae), which allow the passage of electrons. The lamellae were observed using SEM with a detector of transmitted electrons. The lamellae were prepared with the focus on parameters of the protective layer. The chemical composition of Pt-CeOx samples was studied by Energy- Dispersive X-ray spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS). Keywords: Pt-CeOx, lamella, SEM-FIB, EDX, XPS 1
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Modifying the AFM tip using FIB/GIS in scanning electron microscope
Faitová, Hana ; Matolínová, Iva (advisor) ; Dvořák, Filip (referee)
Atom force microscopy (AFM) is a widely used imaging method of solids' surface structure. Collecting the information about relief is realized by a very sharp tip fixed on a flexible cantilever. The surface is scanned by this tip and the flexion of the cantilever is recorded using the reflection of a laser ray. The tip gradually becomes blunt, dirty or destroyed by this process. The work deals with a possibility of reparation of such tips, which still have usable cantilevers. We used focused ion beam (FIB) and gas injection system (GIS) which are built in the scanning electron microscope (SEM). We tried various techniques and parameters of ion etching and deposition. The modified tips were tested using the AFM on KFPP workplace. Powered by TCPDF (www.tcpdf.org)
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Contacting nanostructures for sensor measurements
Chlupová, Šárka ; Matolínová, Iva (advisor) ; Dvořák, Filip (referee)
Title: Contacting nanostructures for sensor measurements Author: Šárka Chlupová Department: Department of Surface and Plasma Science Supervisor: Doc. Mgr. Iva Matolínová, Dr., Department of Surface and Plasma Science Abstract: The bachelor thesis is dealing with contacting nanostructures using electron beam lithography (EBL). Work was carried out in a scanning electron microscope on a mica dielectric substrate with WOx nanorods on the surface in order to prepare a sensor for the detection of H2. In this experiment, parameters for individual sub- processes of EBL were modified. Optimal thicknesses of the PMMA resist 120K (5% anisole) and PMMA 996K (1% anisole) were selected to prepare multilayer resist for an EBL mask. On the resulting bilayer resist electron beam exposure doses were optimized. The appropriate dose was selected and used for creating a matrix designed to contact the WOx nanorods supported on mica. To contact the nanostructures, macrocontacts were deposited on the surface of mica at first, and then the EBL process ran. The result was a conductive connection of the tungsten oxide nanorods by created nanocontacts with macrocontacts. Sensoric properties of the sensor in this way contacted were subsequently successfully tested with H2. Keywords: Sensor, WOx nanorods, Electron beam lithografhy
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The preparation and study of catalytic system Cu(O)-CeO2 using surface analytical methods
Šmíd, Břetislav ; Matolínová, Iva (advisor) ; Plšek, Jan (referee) ; Sofer, Zdeněk (referee)
Title: The preparation and study of catalytic system Cu(O)-CeO2 using surface analytical methods Author: Břetislav Šmíd Department: Department of Surface and Plasma Science Supervisor of the doctoral thesis: Doc. Mgr. Iva Matolínová, Dr. Abstract: This work is concerned with a study of copper/copper oxide - cerium dioxide systems and their interaction with CO and H2O molecules. Investigated samples were prepared in the form of powder catalysts and also as very well defined model inverse systems. The low temperature CO oxidation powder catalysts were studied by means of XPS, XRD, SEM, TEM and in micro-reactor system allowing the CO oxidation examination. The study of H2O adsorption and co-adsorption of H2O with CO were carried out on model inverse systems CeOx(111)/Cu(111) in ultra-high vacuum conditions using X-ray, synchrotron radiation (SRPES), resonant (RPES) photoelectron spectroscopies and LEED. It was observed on the stoichiometric surface water adsorbs molecularly at 120 K while on the reduced surface and surface of CeO2 islands on Cu(111) the H2O adsorption is partially dissociative with formation of OH groups. The increase of Ce3+ species (i.e. surface reduction) observed after H2O adsorption was explained as an electronic effect of the Ce 4f charge accumulation and Ce 5d charge depletion....
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Preparation and characterization of nanostructures for catalysis and gas detection
Haviar, Stanislav ; Matolínová, Iva (advisor) ; Zahoran, Miroslav (referee) ; Plšek, Jan (referee)
First part of this thesis is focused on magnetron sputtering deposited layers of cerium oxide using carbonaceous substrates. Micrographs from scanning and transmission electron microscopes reveal that cerium oxide layers exhibit remarkable roughness and nano-porosity. In this work there are presented optimized key preparation parameters for growth of highly nano-porous layers of cerium oxide on amorphous graphite as well as on graphite foil. The effect of residual atmosphere during the magnetron sputtering deposition is discussed. Results of deposition using oxygen/argon mixture as working gas are presented. A simple growth model is formulated and discussed. Second part deals with utilization of cerium and tungsten oxides as conductometric gas sensors. A testing station was constructed for gathering sensorial properties of such devices. The construction and abilities of the measuring system designed by the author are noted. Preliminary results of measurements of response to hydrogen are presented. Cerium oxide layers suprisingly exhibit measurable response to hydrogen gas. Tungsten oxide nanowires grown on mica substrate were formed into gas sensor via electron beam lithography and show high sensitivity. Powered by TCPDF (www.tcpdf.org)
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Preparation of nanostructure samples in SEM/FIB and their study in TEM
Lavková, Jaroslava ; Matolínová, Iva (advisor) ; Pešička, Josef (referee)
This work is studying the layers of cerium oxide (doped with platinum) prepa- red by magnetron sputtering on different types of substrates. Attention is focused mainly on modes of growth and morfology of (Pt−)CeO2 layers. The study was carried out by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The specimens (lamellas) were created by using focused ion beam (FIB) with respect to transparency for electron beam and material contrast. The emphasis was on elimination of redeposition and minimize the amorphous layer of lamella. Representation of elements was determined by energy-dispersive spectroscopy (EDX) and electron-energy loss spectroscopy (EELS). 1
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Focused ion beam sample preparation for transmission elektron microscopy
Krajňák, Matúš ; Matolínová, Iva (advisor) ; Matolín, Vladimír (referee)
In this work is studied preparation of specimen for transmission electron microscope (TEM). Scanning electron microscope (SEM) device combined with focused ion beam (FIB) is used. There is studied ion and electron induced deposition of P t, W a SiO2 . Lamela is miled by FIB into the specimen and it is transferred to the holder for TEM by nanomanupulating with thungsten tip. The specimen is attached to the tip and to the holder by the deposition of material. After beeing attached to the holder the specimen is thinned by FIB. The created lamelas are compared by SEM and the parameters of process are optimalised so that as few changes as possible are made to the specimen.
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