|
|
Model study of biomolecules bonding to cerium oxide nanoparticles
Pittnerová, Daniela ; Matolínová, Iva (advisor) ; Vorokhta, Mykhailo (referee)
In the last few years cerium oxide due to its convenient properties for biomedical applications has been studied as a promising material for fabrication of third-generation of mediator-less enzymatic biosensors. The bonding of biomolecules with cerium oxide is a crucial parameter, which is difficult to study due to the complexity of the problem. Therefore the model studies on epitaxial and polycrystalline cerium oxide were carried out. In this thesis we continued in this line of the research with the complex study of bonding of amino acids histidine, glycine and sarcosine to cerium oxide nanoparticles. The nanoparticles' properties as the size and chemical composition were measured by electron microscopies and related techniques (TEM, SEM, EDX), and a series of photoemission spectroscopies (XPS, SRPES, RPES and NEXAFS). The dependence of zeta potential on the pH was measure by DLS technique.
|
|
| |
|
|
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.
|
|
|
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
|
|
|
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)
|
|
|
Model study of biomolecules bonding to cerium oxide nanoparticles
Pittnerová, Daniela ; Matolínová, Iva (advisor) ; Vorokhta, Mykhailo (referee)
In the last few years cerium oxide due to its convenient properties for biomedical applications has been studied as a promising material for fabrication of third-generation of mediator-less enzymatic biosensors. The bonding of biomolecules with cerium oxide is a crucial parameter, which is difficult to study due to the complexity of the problem. Therefore the model studies on epitaxial and polycrystalline cerium oxide were carried out. In this thesis we continued in this line of the research with the complex study of bonding of amino acids histidine, glycine and sarcosine to cerium oxide nanoparticles. The nanoparticles' properties as the size and chemical composition were measured by electron microscopies and related techniques (TEM, SEM, EDX), and a series of photoemission spectroscopies (XPS, SRPES, RPES and NEXAFS). The dependence of zeta potential on the pH was measure by DLS technique.
|
|
|
3D tomography of thin film catalysts by means of FIB/SEM techniques
Dinhová, Thu Ngan ; Matolínová, Iva (advisor) ; Khalakhan, Ivan (referee)
One of the actual problems of today society are decreasing sources of fossil fuels. They are raw minerals and by their burning is energy produced. Regarding to the importance of energy in todays world, it's necessary to find an alternative way how to generate energy. A possible solution to this problem are fuel cells, which work on the principle of converting chemical energy into electric energy. At this moment, the development of fuel cells is in progress. In this bachelor thesis, we are concerned with morphology of catalytic layers Pt/CeO2 deposed on a polymer membrane for hydrogen fuel cells. By using of tomography method with focused ion beam system (FIB) we are creating three-dimensional models of their surface structures. 1
|
|
|
Tip modification for high-resolution AFM imaging of nanostructures
Faitová, Hana ; Matolínová, Iva (advisor) ; Vorokhta, Mykhailo (referee)
Atomic force microscopy (AFM) is a young and widely used method of ima- ging surface, nanostructures, biological and other sensitive objects using sharp tip on a flexible cantilever scanning the sample surface. When operating in air it reaches resolution of about several nanometers. The resolution is mainly depen- dent on the used tip. The thesis deals with modification of old tips by carbon nanotubes (CNT) in scanning electron microscope (SEM) using techniques inclu- ding focused ion beam (FIB) and gas injection system (GIS). Several procedures of CNT sample preparation and attaching the CNT on tip are presented. The functionality of modified tips was checked in AFM using the calibration sample consisting of well-defined nanostructures. 1
|
|
|
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
|
|
|
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
|
guest ::
