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Determination of platinum in Brno's agglomeration
Dvořák, Rostislav ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
This thesis is focused on the determination of platinum in samples of road dust and soil by atomic absorption spectrometry. The theoretical part describes the basic physical and chemical properties of platinum, platinum function in automotive converters and its behavior in the environment. In the experimental section summarizes the methods used to decompositions samples, concentration of the analyte and the main results of the measurements.
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The ifluence of inorganic nanoparticles on environmental compartments
Šram, Matěj ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
Nanoparticles are one of the newer risks for the environment. Their consumption is constantly rising and thus their entry into the environment is inevitably increasing. At the same time, nanopollutants are formed as by-products of anthropogenic activity. The theoretical part of the bachelor thesis describes the characteristics of nanoparticles and points out the possible risks in relation to the environment. In the experimental part, this work deals with the effect of platinum nanoparticles on dissolved organic matter. Platinum metals in the form of nanoparticles are significant anthropogenic pollutants, because they are released from automotive catalysts and are therefore the subject of this study.
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Study of CO oxidation on platinum by UHV-SEM
Jaroš, Antonín ; Kolíbal, Miroslav (referee) ; Bábor, Petr (advisor)
This bachelor’s thesis is focused on the study of heterogeneous catalytic oxidation of CO on the surface of platinum, but also in the confined space between platinum and graphene. The thesis is separated into two parts – theoretical and experimental. In the theoretical part, there is a general explanation of important principles regarding this thesis, such as the stucture of scanning electron microscope, growth of graphene, evolution of the catalytic oxidation of CO and oscillatory mode of this reaction, and lastly evolution of the same reaction under the graphene. The experimental part is chronologically concerned about individual tasks of bachelor’s thesis.
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Acid/base properties and reactivity of square planar complexes
DVOŘÁČKOVÁ, Olga
Complexes of platinum and other transition metals are important compounds with many applications including anticancer treatment. This thesis is based on the computational studies dealing with the properties and reactivity of square planar complexes. We showed that the central metal atom acts as a Lewis acid in standard coordination bonds but is able to interact as a Lewis base when being in contact with a Lewis acid. Substitution(s) of the nonleaving ligand(s) enabled a fine-tuning of the reactivity of Pt(II) compounds.
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Study of the influence of nanoparticles on water properties
Šram, Matěj ; Komendová, Renata (referee) ; Řezáčová, Veronika (advisor)
This work deals with the study of the influence of platinum nanoparticles with a size of 3 nm on the properties of water in a porous system. SiO2 with a defined pore size was used as a porous system, which can simulate the mineral component of the soil. The theoretical part deals with the properties of free and porous water and the impact of nanoparticles on the environment. In the experimental part, the properties of free water, water in the porous system and the influence of the presence of platinum nanoparticles on these systems are investigated using differential scanning calorimetry (DSC). The observed processes were melting, solidification and evaporation, and derived quantities such as crystallization and melting point.
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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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Model catalysts based on cerium oxide
Aulická, Marie ; Veltruská, Kateřina (advisor) ; Nemšák, Slavomír (referee) ; Švec, Martin (referee)
This work deals with the preparation of thin cerium oxide films on the Cu(110) single crystal. Physico-chemical properties of this system were studied by surface science techniques (XPS, UPS, ARUPS, LEED, LEEM and STM). The first part of the work concerns interaction of Cu(110) single crystal with oxygen. Condi- tions for formation of O(2x1) and Oc(6x2) oxygen reconstructions were found. Various methods of preparation of CeOx films were discussed. A novel method for continuous control of ceria stoichiometry from CeO2 to Ce2O3 through variation of oxygen vacancy concentration has been developed. Ceria facilitated oxygen spill-over was observed on copper substrate. It was found that a restructuring of copper substrate occurs at the copper-ceria interface with subsequent formation of Cu(13 13 1) facets, which support a Carpet-like ceria overlayer. Interaction of this system with platinum was studied. Finally, high temperature growth of CeOx films was studied and creation of ceria islands exposing the (110) plane was observed. 1
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Highly ordered cobalt oxide thin films for model catalysis
Ronovský, Michal ; Mysliveček, Josef (advisor) ; Švec, Martin (referee)
Hydrogen processing is becoming increasingly important not only in the production of electricity but also during its accumulation. One of the energy storage options are liquid organic hydrogen carriers (LOHC). The main drawback of LOHC is the need for a large amount of thermal energy to release molecular hydrogen. We can bypass this issue using heterogeneous catalysis by transferring hydrogen from LOHC to acetone and using the produced 2-propanol (IPA) in the fuel cell. This innovative strategy of getting electri- cal energy from LOHC can be potentially energetically neutral. In this work, we studied highly ordered Co3O4(111) model catalysts for IPA oxidation in the as-prepared state and enhanced with platinum (Pt) nanoparticles. Catalysts were prepared by Physical Vapour Deposition (PVD) and further investigated by means of Low Energy Electron Diffrac- tion (LEED), X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM) and Temperature Programmed Desorption (TPD). The nucleation process of Pt on the as-prepared Co3O4(111) surface was studied by depositing low amounts 0.04 and 0.13 monolayer (ML) of Pt, that create clusters as small as 2 or 3 atoms with no need for a special nucleation site. We have identified the formation of Pt-induced defects in the atomically flat cobalt oxide...
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Study of CO oxidation on platinum by UHV-SEM
Jaroš, Antonín ; Kolíbal, Miroslav (referee) ; Bábor, Petr (advisor)
This bachelor’s thesis is focused on the study of heterogeneous catalytic oxidation of CO on the surface of platinum, but also in the confined space between platinum and graphene. The thesis is separated into two parts – theoretical and experimental. In the theoretical part, there is a general explanation of important principles regarding this thesis, such as the stucture of scanning electron microscope, growth of graphene, evolution of the catalytic oxidation of CO and oscillatory mode of this reaction, and lastly evolution of the same reaction under the graphene. The experimental part is chronologically concerned about individual tasks of bachelor’s thesis.
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Low Platinum Content Thin Film Catalysts for Hydrogen Proton Exchange Membrane Fuel Cells
Václavů, Michal ; Matolín, Vladimír (advisor)
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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