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Electrochemical Preparation Of Graphene
Oxide For Lfp/Graphene Composites
Krejčí, Pavel
This work deals with issues of application of the graphene material in the field of electrochemical energy storage. It presents the essential way to synthetise graphene oxide material for enhanced electrodes. The general aim is to present growing opportunity of application of graphene based materials in the electrochemical energy storage field.
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Properties Of Graphene Oxide Solutions
Mach, Radoslav
This paper deals with project based on researching of graphene oxide (GO) layers. Main subject is summarizing the basic factors having influence on graphene oxide solvents and its resultant applications on a substrate. There has been made a special substrate made of FR4 composite material for electrical measuring purposes. The goal of this project is creating of homogeneous layer for measuring physical properties of GO layers.
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Use Of Reduced Graphene Oxide In Lithium- And
Sodium-Ion Accumulators
Balcárková, Lucie
Graphene oxide (GO) or reduced graphene oxide (rGO) belongs among artificially, manmade substances. The graphene oxide has got many possible uses and varienty of applications thanks to its specific properties. It is usable in the field of nanoaplications for its catalytic properties as well as in supercapacitors and electrochemical energy sources. This article expores and describes the use of graphene oxide as an active electode material in lithium and sodium-ion batteries.
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Verification of properties of concretes with nanoparticles
Pacltová, Klára ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis deals with the influence of addition of carbon nanoparticles on cement composites. The theoretical part of the diploma thesis is focused on the research of information about carbon nanoparticles, more precisely about carbon nanotubes and graphene oxide. There are summarized methods of dispersing carbon nanotubes and their effects on cement composites. The practical part follows the theoretical part of the research. In the first phase, the correct technique of graphene oxide dispersion was verified. Subsequently, the effects of graphene oxide on the mechanical properties of cement mortars were verified. In the final phase of the diploma thesis, the knowledge gained from the previous part was verified on concrete samples.
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Properties of graphenoid layers
Mach, Radoslav ; Čech, Ondřej (referee) ; Vaněk, Jiří (advisor)
Master thesis “Properties of graphenoid layers” deals with materials of graphenoid nature such as graphene, graphene oxide and its reduced state. The paper effectively summarize basic theoretical knowledge in the first half of its range. In the second half the project deals with practical part consisted of experiments with application of graphene oxide solvents, its analysis and especially comparing properties of non-reduced graphene oxide with its chemically reduced form. Material is examined in a form of applied thin layers on different substrates.
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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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Sorption properties of graphen oxide and styrene composites for SR-85 and CS-137
Brynych, V. ; Kolářová, M. ; Pospěchová, J. ; Tolasz, Jakub ; Štengl, Václav
In the presented work, new composite nanomaterials, based on graphene oxide and styrene, have been developed for the retention purpose. Sr-85 and Cs-137 represent two of the main fission products being present in radioactive wastes from nuclear power cycle. The graphene oxide samples were prepared from natural graphite using high intensity cavitation field in a pressurized (6 bar) batch-ultrasonic reactor. Graphene oxide polystyrene composite was synthesized using direct emulsion polymerization of styrene in the presence of graphene oxide at 90 degrees C. The basic method used for the evaluation of nanomaterial retention properties was batch sorption methodology, based on a contact of solid material with a tracer solution under defined boundary conditions (solid/solution ratio, time, solution composition as pH and ionic strength).
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Photocatalytic water splitting by oxide semiconductors modified with graphen/graphenoxide
Marek, Jiří ; Čáslavský, Josef (referee) ; Cihlář, Jaroslav (advisor)
This master thesis deals with the topic of alternative production of hydrogen as the energy carrier of the future. The primary focus is on the production of hydrogen based on photocatalytical water splitting in the presence of semiconductor materials (especially modified and unmodified TiO2). The aim of the thesis is a synthesis of nanostructured oxide, graphene/graphene oxide particles and its composites, and a study of its structures and photocatalytical properties regarding photolysis of water. Products of the syntheses are described from the point of view of phase composition, surface area and photocatalytical activity. The main output of the thesis is a discussion of the influence of alkaline complex forming reagents on the hydrothermal low-temperature synthesis of biphasic TiO2, and a study of the influence of graphene/graphene oxide modification on photocatalytical activity of biphasic TiO2.
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Study on interactions between lipase and carbon-based support
Hamrlová, Romana ; Voběrková, Stanislava (referee) ; Hermanová, Soňa (advisor)
Tématem diplomové práce je imobilizace lipáz a konkrétně studium interakcí mezi lipázou a nosičem na bázi uhlíku. Lipáza izolovaná z kmene Rhizopus arrhizus byla adsorbována přímo na různé typy grafen oxidu (a1, a, b, c a d) a na grafen oxid typu a1 modifikovaný poly(ethylenglykolem), PEG-a1. Enzym adsorbovaný na nosič a1 byl následně sesítěn pomocí glutaraldehydu a vzorek byl označen jako GA(RA-a1). Vliv hydrofobního charakteru povrchu nosiče na účinnost imobilizace byl potvrzen vyšší úchovou počáteční aktivity enzymu imobilizovaného na více hydrofobním nosiči (nižší koncentrace polárních skupin) i při vyšší koncentraci rozpustného enzymu v roztoku. Stanovení enzymové aktivity bylo provedeno spektrofotometricky za použití p-nitrofenyl laurátu (p-NPL) jako substrátu. Pro imobilizovaný a volný enzym byly stanoveny základní biochemické a kinetické parametry. Optimální pH kovalentně imobilizovaného enzymu bylo posunuto do více kyselého oblasti (pH 7-8) ve srovnání s volným enzymem, kdy bylo optimum dosaženo při pH 9. Tepelná stabilita imobilizovaného enzymu byla výrazně zlepšena v případě vzorku GA(RA-a1), kde bylo aplikován glutaraldehyd po adsorpci enzymu na nosič. Sesíťování adsorbovaného enzymu pomocí glutaraldehydu vedlo ke zlepšení tepelné stability vzorku, a to pravděpodobně v důsledku intermolekulárních kovalentních vazeb. Na základě měření stability enzymu při teplotě 4 C ve fosfátovém pufru bylo prokázáno značné zlepšení úchovy lipolytické aktivity imobilizovaného vzorku oproti volnému enzymu. Volný enzym ztratil více než 84 % své původní aktivity za 42 dní, zatímco imobilizovaný enzym na nosiči c si zachoval 100 % své původní aktivity. Nejlepší stabilitu enzymu při úchově měl nosič c, když si po 180 dnech stále zachoval 87 % své původní aktivity.
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Effects of detergents on activity, thermostability and aggregation of immobilized lipases
Bančáková, Anna ; Voběrková, Stanislava (referee) ; Hermanová, Soňa (advisor)
Predmetom tejto diplomovej práce bolo štúdium vplyvu detergentov na aktivitu, termostabilitu a agregáciu voľnej a imobilizovanej formy komerčného preparátu lipázy izolovanej z mikroskopickej huby Rhizopus arrhizus. Teoretická časť obsahuje ucelenú rešerš popisujúcu štruktúru, mechanizmus účinku a priemyselný význam spomínanej hydrolázy spolu s popisom chemických účinkov detergentov, pričom dôraz bol kladený predovšetkým na skupinu neionogénnych detergentov s názvom tweeny. V experimentálnej časti bol študovaný efekt tweenov na rozpustnej a imobilizovanej forme RA lipázy. Imobilizácia spočívala v priamej adsorpcii enzýmu na neupravený nosič. Ako nosič bol použitý oxidovaný grafén ošetrený tweenom (tween 20, 60, 80). Aktivita enzýmu bola stanovená spektrofotometricky za pomoci substrátu p-nitrofenyl laurátu. Zvýšenie aktivity voľnej lipázy (104 % oproti maximálnej hodnote) bolo zaznamenané pri použití tweenu 20 o koncentrácii vysoko nad hodnotou kritickej micelárnej koncentrácie (10 mmol•dm-3). Na základe štúdie imobilizačných podmienok, boli nastavené ideálne parametre pre dosiahnutie účinnej imobilizácie v spojení s čo najvyššou lipolytickou aktivitou (koncentrácia enzýmu 0,1 mg•ml-1, fosfátový tlmivý roztok pH 7,2, koncentrácia tweenu 10,8 mmol•dm-3, čas imobilizácie 1 hodina). Obe formy lipázy vykazovali maximálnu aktivitu pri 35 °C. Optimálne pH sa u imobilizovanej lipázy posunulo na hodnotu 8, v porovnaní s voľnou formou, ktorej pH optimum bolo stanovené na 9. Tepelná stabilita vykazovala približne rovnaký priebeh u oboch foriem skúmanej hydrolázy. Avšak v prípade štúdia stability enzýmu pri dlhodobej úschove bolo po imobilizácii zistené výrazné zlepšenie tohto parametru.
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