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Electrochemical preparation of graphene oxide and its utilization in LiFePO4 composites
Krejčí, Pavel ; Chladil, Ladislav (referee) ; Čech, Ondřej (advisor)
This work deals with issues of application of the graphene material in the field of electrochemical energy storage. It includes basic graphene properties, the overview of methods for the production of lithium-iron-phosphate/graphene composites and results of different research approaches. The general aim is to present growing opportunity of application of graphene based composites in the electrochemical energy storage field. In the experimental part of this work, a electrochemical exfoliation of graphite and a production of LFP/G composites with different amount of graphene material and with different types of graphene material are carried out. This work includes also x-ray diffraction spectroscopy measurements and the evaluation of impacts of graphene additives on final properties of the electrochemical energy storage.
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Kompozity nanouhlíkatých materiálů pro ochranu zemědělských rostlin před houbovými patogeny
Burešová, Michaela
Graphene oxide (GO) belongs to carbon-based nanomaterials (CBNs) and is capable of bonding with various molecules, thanks to the presence of functional oxygen groups in its structure, created during graphene oxidation. This mechanism can be applied on nutrient and pesticide delivery and improve their utilization by plants. Sulphur is an essential nutrient and also has fungicidal properties. In this study, graphene oxide was synthesized and used to make two nanocomposites containing sulphur. GO and nanocomposites were then characterized. Nanocomposites were tested for phytotoxicity, and their potential fungicidal properties were studied. Both nanocomposites showed significant fungistatic effect against grey mold when tested on plates with medium. However, when tomato leaves were treated with nanocomposites, inhibition effect against mycelium growth was ineffective.
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Využití symbiotických mikroorganismů a podpůrných nanočástic při zvyšování odolnosti zeleniny v podmínkách vodního stresu
Stašková, Nicole
This thesis deals with the influence of symbiotic microorganisms and supporting nanoparticles on vegetable. Lettuce (Lactuca sativa var. capitata L.), variety "ALAMER" was chosen to be the model vegetable. Symbiotic microorganisms Rhizophagus irregularis and Bacillus subtilis were applied to lettuce plants, and GO-N-1 nanoparticles containing graphene oxide and dicyandiamide were applied to lettuce leaves. The following parameters were evaluated on lettuce plants: height of the above-ground part of plants, weight of the above-ground part of the plants, normalized differentiation index (NDVI), quantum yield of photosynthesis (QY), nitrate content in fresh lettuce leaves and the occurance of mycorrhizical structures.
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The Interaction of Graphene Oxide with Humic Acids, a Computational Study
FERLIN, Stefan
This study was focused on the interactions of Graphene oxide with humic acids in aqueous solutions. Additionally, to this work, Graphene oxide and water interactions with and without the addition of ions were studied. The behavior of a fulvic acid in the presence of Graphene oxide has been investigated as well. The study was performed using computer simulations that were achieved by Molecular Dynamics simulations. These simulations provided useful data on a nanometer scale.
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Modification of capillary wall by graphene for separation applications
Ptáčková, Aneta ; Lochman, Lukáš (advisor) ; Kučera, Radim (referee)
CHARLES UNIVERSITY FACULTY OF PHARMACY IN HRADEC KRÁLOVÉ Department of Pharmaceutical Chemistry and Pharmaceutical Analysis Candidate: Aneta Ptáčková Supervisor: PharmDr. Lukáš Lochman, Ph.D. Title of thesis: Modification of capillary wall by graphene for separation applications Capillary electrophoresis (CE) is a highly efficient separation method. Substances are separated due to their different mobility in an electric field. The CE modes of operation can be modified in different ways, e.g. capillary electrochromatography or micellar electrokinetic capillary chromatography. Modification of the inner wall of the capillary is believed to help improve separation efficiency and selectivity. Graphene is carbon with a hexagonal structure in form of two-dimensional sp2 single-atom-thick sheets. Graphene seems to be a suitable material for separation application due to its excellent properties such as large surface area and affinity to aromatic ring through π-π interactions. Our work is focused on the modification of the capillary wall by graphene. One of the methods of capillary wall modification is the Layer-by-Layer method via layering of differently charged substances bounded by electrostatic forces. Another method is chemical coating employing covalent interactions. Different combinations of polymers...
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The oxygen modification of the graphene structures for biosensors
Mikerásek, Vojtěch ; Bartošík, Miroslav (referee) ; Mach, Jindřich (advisor)
The bachelor thesis deals with the modification of CVD graphene by oxygen atoms. The theoretical part describe the structure of graphene oxide and its physical properties. Methods of production of this material and its use in biosensors are also described. The practical part describes the preparation of monolayer graphene on a silicon wafer. The main attention was paid to the oxidation of graphene by atomic oxygen and its modification in oxygen plasma. The samples were measured during process of oxidation at individual time intervals using XPS.
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Nanoparticle treatment technology to improve their dispersibility for use in cemt composites
Závacký, Jakub ; Sťahel,, Pavel (referee) ; Hela, Rudolf (advisor)
The diploma thesis deals with the possibility of using the addition of nanoparticles to improve the properties of cement composites. The theoretical part summarizes the findings of research in this area with a focus on methods of dispersion of nanoparticles and their treatment for use in cement composites. The experimental part focuses on the comparison of methods of dispersion and plasma treatment of reduced graphene oxide (rGO) nanoparticle solutions from the point of view of the agglomeration process. During this work, a method of systematic optical/visual monitoring of sedimentation/agglomeration was developed to complement sophisticated methods such as spectrophotometry (UV/Vis) and electron microscopy (SEM). Furthermore, the effect of the addition of rGO on the properties of cement mortar, in the form of aqueous solutions prepared by the dispersion methods determined in the previous section, was investigated.
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Characterization Of Electrical Properties Of Graphene-Based Materials On Mems Structures
Brodský, Jan
This work presents characterization of basic electrical properties of graphene and graphene oxide. Graphene was prepared by chemical reduction of graphene oxide. The experimental part of this work describes the process of graphene oxide and reduced graphene oxide sample preparation and measurement of its current-voltage characteristic by two-point probe method. Measurement is carried out on MEMS structure, which can be used for mechanical bending. Such structure will serve for utilization of graphene and other 2D materials.
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HYDROGEN STORAGE PROPERTIES OF GRAPHENE OXIDE MATERIALS PREPARED BY DIFFERENT WAYS
Král, Lubomír ; Čermák, Jiří ; Bytesnikova, Z.
Graphene-based materials show unique properties. These single layered materials consist of 2D structure of carbon atoms, belong to the strongest known materials, that are very mechanically flexible, optically transparent and that are excellent electrical and thermal conductors. Recently, several studies on these types of materials have highlighted the potential of this material for hydrogen storage (HS) and raised new hopes for the development of an effective solid-state HS media. In the present paper, the structure and HS properties of graphene oxide (GO) and chemically reduced graphene oxide (rGO) produced by different procedures were studied. Hydrogen sorption characteristics of GO and rGO were measured using the Sieverts-type gas sorption analyzer PCT-Pro Setaram Instrumentation. The study of HS was carried out at temperature range from 198 K to 423 K under hydrogen pressure from 1x10(-4) to 4 MPa. \n\nFor the HS point of view, the advantage of GO or rGO compared to graphene, is the presence of multiple chemical groups that can be used for introducing modifiers and their superior spreading on the materials surface. The suitably functionalized GO or rGO materials could potentially exhibit outstanding HS properties.
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HYDROGEN STORAGE PROPERTIES OF GRAPHENE OXIDE MATERIALS PREPARED BY DIFFERENT WAYS
Král, Lubomír ; Čermák, Jiří ; Bytesnikova, Z.
Graphene-based materials show unique properties. These single layered materials consist of 2D structure of carbon atoms, belong to the strongest known materials, that are very mechanically flexible, optically transparent and that are excellent electrical and thermal conductors. Recently, several studies on these types of materials have highlighted the potential of this material for hydrogen storage (HS) and raised new hopes for the development of an effective solid-state HS media. In the present paper, the structure and HS properties of graphene oxide (GO) and chemically reduced graphene oxide (rGO) produced by different procedures were studied. Hydrogen sorption characteristics of GO and rGO were measured using the Sieverts-type gas sorption analyzer PCT-Pro Setaram Instrumentation. The study of HS was carried out at temperature range from 198 K to 423 K under hydrogen pressure from 1x10(-4) to 4 MPa.
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