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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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Characterization of highly porous Pd-modified SnO2 sputtered thin films for H2 detection
Chundak, Mykhailo ; Veltruská, Kateřina (advisor) ; Jiříček, Petr (referee) ; Šmíd, Břetislav (referee)
Title: Characterization of highly porous Pd-modified SnO2 sputtered thin films for H2 detection Autor: Mgr. Mykhailo Chundak Department/Institute: Department of Surface and Plasma Science Supervisor of the doctoral thesis: RNDr. Kateřina Veltruská, CSc., Department of Surface and Plasma Science Abstract: This doctoral thesis contains the study of tin dioxide and Pd-doped tin dioxide samples deposited by magnetron sputtering utilizing glancing angle deposition (GLAD). Influence of the deposition parameters on the change of morphology, crystalline structure and chemical state was studied. The samples were characterized by a variety of techniques, such as: X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), synchrotron radiation photoelectron spectroscopy (SRPES), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). Prepared samples showed high porosity which could be controlled by deposition parameters (angle of the deposition, gas pressure and power of magnetron discharge). Highly porous SnO2 GLAD samples and Pd modified SnO2 GLAD samples were deposited on the substrates at room temperature and 300 řC. These samples were found to be polycrystalline with certain fraction of amorphous contribution, given by preparation conditions. The size of the...
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Physically chemical properties of epitaxial films CeO2/Cu(110)
Aulická, Marie ; Veltruská, Kateřina (advisor) ; Nehasil, Václav (referee)
In this work ways of preparation of thin epitaxial cerium oxide film on Cu(110) surface were studied. X-ray photoelectron spectroscopy (XPS), X-ray photoelectron difraction (XPD), low energy electron difraction (LEED), ion scattering spectroscopy (ISS) and scanning tunneling microscopy (STM) were used for the characterization of prepared systems. The island structure of CeO2 was prepared by the method of reactive evaporation in oxygen atmosphere. The influence of temperature on the electronic structure and morphology was studied. At the temperature above 550 ˚C partial reduction to Ce2O3 and reordering of the islands to the CeO2(331) structure was observed. The ceria promoted oxidation of copper surface was approved, since the clean c(6x2) reconstruction of the surface was observed at the oxygen exposure 1,5 order of magnitude lower then on Cu(110) alone. The other model system was prepared by cerium evaporation to the oxygen precovered Cu(110) surface. The mix of (2x1) and c(6x2) surface reconstruction was formed by oxygen exposition at 300 ˚C. Cerium was deposited on this surface, also at 300 ˚C. During the following heating to 500 ˚C the formation of epitaxial film Ce2O3(0001) was observed, accompanied by the formation of large hundreds nm long smooth band structures in the [11̄0] direction.
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Model catalysts based on cerium oxide
Aulická, Marie ; Veltruská, Kateřina (advisor)
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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Language and Ageing - Cognitive and Educational Aspects in the Elderly with Special Focus on Cognitive Training in a Foreign Language in People with Dementia
Veltruská Šmídová, Kateřina ; Pípalová, Renata (advisor) ; Lancová, Klára (referee)
The thesis explores cognitive as well as educational aspects in elderly people. The main emphasis is put on investigating the influence of cognitive training carried out in a foreign language on the elderly suffering from dementia. Having described the basic anatomy of the nervous system, neurolinguistic theories as well as ageing and having dealt with cognitive aspects in relation to language learning, the thesis aims at performing an experiment that should help dementia clients to broaden their vocabulary in a foreign language. This is to be achieved through individual therapy- like units using worksheets created specifically for these purposes. The results indicate that cognitive training in a foreign language is beneficial to dementia clients and could be used more extensively. The worksheets were redesigned in order to facilitate their further use by specialised teachers or lectures working with mentally healthy seniors. Key words ageing, dementia, language, cognitive training, neurolinguistics, geragogy
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Electronic and structural properties of model catalysts based on cerium oxide
Duchoň, Tomáš ; Veltruská, Kateřina (advisor) ; Bartoš, Igor (referee) ; Kullgren, Jolla (referee)
Catalysts based on cerium oxide are ubiquitous in industrial-scale chemical conversion. Here, a thorough study of their fundamental properties is undertaken via a model system ap- proach with the goal of furthering rational design in heterogeneous catalysis. A focus is put on understanding the behavior of oxygen vacancies in cerium oxide with respect to atomic co-ordination and electronic structure perturbations. Utilizing state-of-the-art probing tech- niques, a scalable model system framework is developed that allows for control over both the oxygen vacancy concentration and local co-ordination. High precision of the innova- tive approach facilitated observation of new phases of substoichiometric cerium oxide and lead to a first-of-a-kind investigation of the electronic structure of cerium oxide throughout isostructural transition from CeO2 to Ce2O3. The acquired results advance fundamental understanding of essential properties of cerium oxide that are relevant to its utilization in heterogeneous catalysis and open new pathways for functionalization of cerium oxide-based materials. Furthermore, the methodology developed in the thesis is transferable to other important reducible oxides. 1
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Physical and chemical properties of CeOx/SrTiO3(100) films
Schusser, Jakub ; Veltruská, Kateřina (advisor) ; Ševčíková, Klára (referee)
A study of epitaxial growth of CeOx on SrTiO3(100) surface in CeO2(100)/SrTiO3(100) orientation by reactive vapor deposition in oxygen atmosphere is desirable for widening the current knowledge in the field of ceria-based model catalysts. This work was aimed at determining physical parameters necessary for the growth of CeO2(100) films (substrate temperature, oxygen pressure and deposition rate), atomic structure of the CeO2(100) surface and structure-stoichiometry relation during reversible CeO2↔Ce2O3 transition. Surface science methods were used in order to follow the structural and chemical characteristics of prepared films, such as XPS, XPD, ISS and LEED. The morphology of the prepared films was examined in detail using scanning tunnelling microscope (STM). We also examined the interaction with platinum, which represents the next step towards designing a ceria based catalysts with low noble metal content. Also the redox interaction properties of CeOx and hydrogen were studied.
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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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