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Electron lithography in scanning electron microscope
Haviar, Stanislav ; Matolín, Vladimír (advisor) ; Lopour, Filip (referee)
Electron beam lithography in a scanning electron microscope Tescan Miran LMH is described. Detailed parametres of preparation procedure of metal structures with characteristic dimensions below 100 nm were obtained. Additionally, a preparation of square arrays of sub 100-nm metal dots with 1 µm periode is being discussed. The lithography was performend with self-prepared resist layers (thickness < 25 nm), parameters of the spin-coating procedure are listed as well. A construction of a model single-wire sensor is described. The sensor had macroscopic gold contacts with thin (< 200 nm) tin oxide wires in between. The structures were investigated by means of scanning electron microscopy and atomic force microscopy.
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Synchrotron Radiation PhotoElectron Studyof CeOx-Pd,Sn,Au Model Catalysts
Škoda, Michal ; Matolín, Vladimír (advisor) ; Čech, Vladimír (referee) ; Plšek, Jan (referee)
The doctoral thesis deals with study of model catalytic systems Ce(Ox)-Pd(111), Sn-CeO2(111) and Au-CeO2(111). The metal-metal and metal-oxide interactions are investigated by means of photoelectron spectroscopy method (PES), first of all resonant photoelectron spectroscopy (RPES). The RPES method showed, that the chemical state modifications of the system induce significant modifications in the band structure of its atoms implicating dramatic valence band changes. The RPES method has appeared to be a powerful instrument for valence band electron structure study.
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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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Investigation of new anode materials for methanol polymer fuel cells
Fiala, Roman ; Matolín, Vladimír (advisor) ; Sofer, Zdeněk (referee)
We investigated new types of anode catalysts for polymer membrane fule cell (PEMFC). Pt doped CeO2 thin lms were deposited by rf-magnetron sputtering on carbon nanotubes (CNTs) directly grown on GDL by using CVD. We observed considerable increase of speci c power by 1000 times and more in comparison with standard PtRu anode catalyst. For this new anode system we obtained the speci c power of 44.3 W/mg(Pt). The interaction of Pt with CeO2 layers with di erent substrates was investigated by using photoelectron spectroscopy. The results showed that platinum was in cationic state and the Pt2+/Pt4+ ratio was dependent of substrates materials. We also demonstrated that the performance of direct methanol fuel cell with Pt and PtRu catalyst can be dramatically increased simply by adding sodium hydroxide to methanol fuel. Cell voltage and power output characteristics were studied in dependence on current, temperature and concentration of sodium hydroxide. Endurance test was performed and the fuel cell exhibited stable response. Power density of 80.7 mW/cm2 was recorded for 2 M methanol/2 M sodium hydroxide fuel 30řC.
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Study of valence band structure of transition metals and alloys by ARUPS method
Pira, Peter ; Matolín, Vladimír (advisor) ; Libra, Jiří (referee)
Heterogeneous catalysis is one of many interesting part of physics, witch surface science study. Knowing of importance of processes in catalytic reaction should predict properties of new bimetallic systems. The main task of this diploma thesis was the study of valence band of transition metals. In this diploma thesis we studied bimetallic system of palladium and tin by ARUPS. We also used methods XPS, XPD and LEED, which are classical applications in surface physics.
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Study of thin film catalysts for oxygen reduction reaction on proton exchange membrane fule cell cathode
Komárková, Zuzana ; Matolín, Vladimír (advisor) ; Václavů, Michal (referee)
In this thesis, we present the investigation of influence of methanol crossover, which significantly decreases the performance of DMFC (Direct Methanol Fuel Cell). Additionally the poisoning effect occurs on the cathode side. The durability of cathode catalyst exposed by methanol vapor is studied. Moreover, the regene- rative behavior after exposition has been found. The comparison of commercial catalyst with our own sputtered Pt and PtCo and PtRu thin layers as cata- lyst is presented. Obtained results have shown that PtCo is reasonable compro- mise between pure Pt, which has high performance, and PtRu, which is tolerant to methanol poisoning. Future research should further evaluate the advantages of PtCo cathode catalyst prepared by standard procedures and its market poten- tial in comparison with PtRu. 1
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