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1
Avril, Florian. "Contribution à l'élaboration d'un supercondensateur à basse de graphène." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS034/document.
Повний текст джерелаАнотація:
L'utilisation de l'énergie des micro-sources de production d'électricité est un concept prometteur qui consiste à récolter des sources d'énergie faible et diffuse présent dans notre environnement pour l’alimentation de systèmes autonomes. Le nombre en croissance de nouveaux appareils miniaturisés et communicants dans les domaines civils et militaires devrait accentuer le phénomène de dépendance énergétique et ouvre de nouveaux marché.Parmi les éventuelles sources d’énergies renouvelables, l’énergie solaire est la source la plus prometteuse car elle est potentiellement la plus puissante et la mieux répartie. Le développement de ces systèmes de récupération des micro-sources d’énergie passe par de faibles coûts avec substrat souple (papier,polymère) et des matériaux facilement exploitables. Après la récupération de l’énergie, il est nécessaire pour les systèmes autonomes de stocker l'électricité.Dans cet objectif, les supercondensateurs sont les candidats idéaux. En effet, Le principal avantage des supercondensateurs par rapport aux batteries est leur haute densité de puissance (la collecte rapide de l’énergie) ainsi qu'une longue durée de vie. La thèse concerne donc la fabrication d’un supercondensateur et in fine le couplage avec une cellule solaire. Les travaux concernent spécifiquement l’étude de l'oxyde de graphène (GO) synthétisé par la méthode Hummers et Marcano, de sa réduction en oxyde de graphène réduit (RGO) par les voies chimique et électrochimique et de réalisation du supercondensateur. Dans ce projet, les propriétés de l'oxyde de graphène réduit (RGO) seront optimisées lors de l'étape de réduction et le matériau sera mis en forme dans une structure sandwich (RGO/ électrolyte /RGO) ou interdigité Mots clés: Graphène,supercondensateur, oxyde de graphène, micro-source d'énergieThe use of micro-power generation energy is a promising concept that consists in harvesting low and diffuse energy sources present in our environment for the supply of autonomous systems. The growing number of new miniaturized and communicating devices in civil and military fields should accentuate the phenomenon of energy dependence and open up new markets.Among possible sources of renewable energy, solar energy is the most promising source because it is potentially the most powerful and best distributed. The development of these micro-energy recovery systems involves low costs with flexible substrate (paper, polymer) and easily exploitable materials. After energy recovery, it is necessary for the autonomous systems to store electricity.For this purpose, supercapacitors are ideal candidates. Indeed, the main advantage of supercapacitors over batteries is their high power density (fast energy collection) as well as a long cycle life. The thesis concerns the manufacture of a supercapacitor and ultimately coupling with a solar cell. The work specifically concerns the study of graphene oxide (GO) synthesized by the Hummers and Marcano methods, its reduction in reduced graphene oxide (RGO) by chemical and electrochemical routes and the realization of supercapacitor. In this project, the properties of reduced graphene oxide (RGO) will be optimized during the reduction step and the material will be shaped into a sandwich structure (RGO / electrolyte / RGO) or interdigitated.Keywords: Graphene,supercapacitor, graphene oxide,energy micro-source
2
Nyangiwe, Nangamso Nathaniel. "Graphene based nano-coatings: synthesis and physical-chemical investigations." Thesis, UWC, 2012. http://hdl.handle.net/11394/3237.
Повний текст джерелаАнотація:
Magister Scientiae - MScIt is well known that a lead pencil is made of graphite, a naturally form of carbon, this is important but not very exciting. The exciting part is that graphite contains stacked layers of graphene and each and every layer is one atom thick. Scientists believed that these graphene layers could not be isolated from graphite because they were thought to be thermodynamically unstable on their own and taking them out from the parent graphite crystal will lead them to collapse and not forming a layer. The question arose, how thin one could make graphite. Two scientists from University of Manchester answered this question by peeling layers from a graphite crystal by using sticky tape and then rubbing them onto a silicon dioxide surface. They managed to isolate just one atom thick layer from graphite for the first time using a method called micromechanical cleavage or scotch tape. In this thesis chemical method also known as Hummers method has been used to fabricate graphene oxide (GO) and reduced graphene oxide. GO was synthesized through the oxidation of graphite to graphene oxide in the presence of concentrated sulphuric acid, hydrochloric acid and potassium permanganate. A strong reducing agent known as hydrazine hydrate has also been used to reduce GO to rGO by removing oxygen functional groups, but unfortunately not all oxygen functional groups have been removed, that is why the final product is named rGO. GO and rGO solutions were then deposited on silicon substrates separately. Several characterization techniques in this work have been used to investigate the optical properties, the morphology, crystallography and vibrational properties of GO and rGO.
3
Arbuzov, A. A., V. E. Muradyan, and B. P. Tarasov. "Synthesis of Few-layer Graphene Sheets via Chemical and Thermal Reduction of Graphite Oxide." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35063.
Повний текст джерелаАнотація:
Few-layer graphene sheets were produced from graphite oxide (GO) chemical and thermal reduction.
For the chemical reduction of GO as reducing agents were used hydrazine hydrate, hydroxylammonium
chloride, sodium borohydride and sodium sulfite. The reduced material was characterized by elemental
analysis, thermo-gravimetric analysis, scanning electron microscopy, X-ray diffraction, Fourier transform
infrared and Raman spectroscopy. A comparison of the deoxygenation efficiency of graphene oxide suspension by different method or reductants has been made, revealing that the highest degree of reduction was
achieved by thermal reduction and using hydrazine hydrate and hydroxylammonium chloride as a reducing agents.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35063
4
Sokolov, Denis A. "Investigation of Graphene Formation from Graphite Oxide and Silicon Carbide." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/53642.
Повний текст джерелаАнотація:
Graphene is a novel two dimensional material that is revolutionizing many areas of science and it is no surprise that a significant amount of effort is dedicated to its investigation. One of the major areas of graphene research is the development of procedures for large scale production. Among many recently developed methodologies, graphene oxide reduction stands out as a straightforward and scalable procedure for producing final material with properties similar to those of graphene. Laser reduction of graphite oxide is one of the novel approaches for producing multilayer graphene, and this work describes a viable approach in detail. It is determined that a material which is comprised of a combination of laser reduced graphite oxide-coupled to an unreduced graphite oxide layers beneath it, produces a broadband photosensitive material. The efficiency of light conversion into electrical current is greatly dependent upon the oxygen content of the underlying graphite oxide. Developing novel ways for reducing graphite oxide is an ongoing effort. This work also presents a new method for achieving complete reduction of graphite oxide for producing predominantly sp2 hybridized material. This approach is based on the irradiation of graphite oxide with a high flux 3 keV Ar ion beam in vacuum. It is determined that the angle of irradiation greatly influences the final surface morphology of reduced graphite oxide. Also, multilayer epitaxial graphene growth on silicon carbide in ultra-high vacuum was investigated with quadrupole mass spectrometry (QMS). Subliming molecular and atomic species were monitored as a function of temperature and heating time. The grown films were characterized with X-ray photoelectron spectroscopy coupled with Ar ion depth profiling.
5
Pakulski, Dawid. "Graphene based materials and their potential applications." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAF060.
Повний текст джерелаАнотація:
Cette thèse de doctorat a pour objectif scientifique la synthèse de matériaux bidimensionnels fonctionnalisés (graphène et oxyde de graphène) et leur caractérisation physicochimique complète, avec un accent particulier apporté sur les propriétés d'adsorption et de stockage d'énergie. Nous avons démontré que la modification covalente de l'oxyde de graphène (GO) avec un polymère organique (BPEI) affecte très favorablement l'efficacité du processus d'adsorption. Les valeurs de la capacité maximale d'adsorption (qmax) des ions de métaux lourds favorisent de manière significative ce matériau par rapport à la majorité des adsorbants connus à base de carbone. En outre la fonctionnalisation de GO avec l'aminosilicate mésoporeuse (SiO2NH2) conduit à l'obtention d'un adsorbant efficace et rapide des colorants organiques cationiques (MB, RhB, MV). En plus nous avons prouvé que la fonctionnalisation du graphène (EEG), en utilisant les sous-unités de surfactant POM, a montré que ce type de matériau hybride organique-inorganique est très stable et présente des propriétés électriques intéressantes pouvant être utilisées dans la production de supercondensateursScientific purpose of this doctoral dissertation is synthesis of functionalized two-dimensional materials (graphene and graphene oxide) and their comprehensive physicochemical characterization, with particular emphasis on adsorption and energy storage properties. We could demonstrate that covalent modification of graphene oxide (GO) with an organic polymer (BPEI) very favorably affects the efficiency of the adsorption process. The maximum adsorption capacity (qmax) values for heavy metal ions significantly favour this material in comparison to the majority of known carbon adsorbents. Moreover, functionalization of GO with mesoporous aminosilica (SiO2NH2) leads to obtaining an efficient and rapid adsorbent of organic cationic dyes (MB, RhB, MV). ln addition we proved that the functionalization of graphene (EEG) using the POM-surfactant su bu nits proved that this type of organic-inorganic hybrids material is very stable and have interesting electrical properties with potential application in the production of supercapacitors
6
Alami, Omar. "Oxyde de graphène fonctionnalisés par des dendrons et dendrimères pour des applications en oncologie." Thesis, Toulouse 3, 2022. http://www.theses.fr/2022TOU30086.
Повний текст джерелаАнотація:
Le graphène, une monocouche d'atomes de carbone densément tassée dans un réseau en nid d'abeille, a été isolé pour la première fois en 2004. Ces dernières années, la recherche sur le graphène et ses dérivés a suscité un intérêt considérable dans un large éventail d'activités de recherche grâce à ses propriétés intéressantes. La voie la plus facile et polyvalente pour obtenir des nanocomposites à base de graphène consiste à oxyder le graphite naturel pour obtenir l’oxyde de graphène (GO), un matériau ayant une surface riche en fonctions chimiques modifiables. Des nanocomposites à base d’oxyde de graphène ont été synthétisés pour des applications potentielles dans l'électronique, le stockage d'énergie, la catalyse et la sorption, le stockage, la séparation et la détection de gaz ainsi que dans le domaine biomédical. Les dendrimères sont des macromolécules particulièrement intéressantes pour un très grand nombre d'applications dans des domaines extrêmement variés. Cet intérêt réside essentiellement dans leurs propriétés de coopérativité et de multivalence, ainsi que dans leur très haute capacité d'encapsulation ou de fixation de petites molécules, et ceci dans un volume de taille nanométrique. Cette caractéristique structurale est la conséquence de leur architecture unique ramifiée contenant un cœur central et possédant de nombreuses fonctions périphériques. Les dendrimères sont donc des outils très intéressants pour la délivrance de médicaments et d'acides nucléiques. Dans ce travail nous allons développer des approches simples pour décorer la surface de l’oxyde de graphène avec des dendrons et dendrimères phosphorés pour des applications en oncologie. Dans un premier temps on va effectuer la synthèse des dendrimères phosphorés classiques, et des dendrons AB5, ensuite le greffage des différents monomères sur leur surface. En parallèle la préparation de l’oxyde de graphène (GO) ainsi que la modification de la surface de GO par différentes méthodes a été effectué, et finalement le greffage des différents dendrons sur la plateforme de l’oxyde de graphène a permis d'obtenir de nouveaux matériaux hybrides qui seront testés biologiquementGraphene, a monolayer of carbon atoms densely packed in a honeycomb lattice, was first isolated in 2004. In recent years, research on graphene and its derivatives has generated considerable interest in a wide range of research activities thanks to its interesting properties. The easiest and most versatile way to obtain graphene-based nanocomposites is to oxidize natural graphite to obtain graphene oxide (GO), a material with a surface rich in modifiable chemical functions. Graphene oxide nanocomposites have been synthesized for potential applications in electronics, energy storage, catalysis and sorption, gas storage, separation and detection as well as in the biomedical field. Dendrimers are particularly advantageous macromolecules for a very large number of applications in extremely varied fields. This interest resides essentially in their properties of cooperativity and multivalence, as well as in their very high capacity for encapsulation or fixing of small molecules, and this in a volume of nanometric size. This structural characteristic is the consequence of their unique branched architecture containing a central core and having many peripheral functions. Dendrimers are very interesting tools for the delivery of drugs and nucleic acids. In this work we will develop simple approaches to decorate the surface of graphene oxide with phosphorus dondron and dendrimers in order to create new hybrid materials with new properties. First, the synthesis of classical phosphorus dendrimers and of AB5 dendrons will be carried out, followed by the grafting of the different monomers on their surface. In parallel the preparation of graphene oxide (GO) as well as the modification of the GO surface with different methods will be carried out, and finally the grafting of the different dendrons on the platform of graphene oxide will afford new hybrid materials that will be biologically tested
7
Leve, Zandile Dennis. "Determination of paracetamol at the electrochemically reduced graphene oxide-metal nanocomposite modified pencil graphite (ERGO-MC-PGE) electrode using adsorptive stripping differential pulse voltammetry." University of Western Cape, 2020. http://hdl.handle.net/11394/7350.
Повний текст джерелаАнотація:
>Magister Scientiae - MScThis project focuses on the development of simple, highly sensitive, accurate, and low cost electrochemical sensors based on the modification of pencil graphite electrodes by the electrochemical reduction of graphene oxide-metal salts as nanocomposites (ERGO-MC-PGE; MC = Sb or Au nanocomposite). The electrochemical sensors ERGO-Sb-PGE and ERGO-Au-PGE were used in the determination of paracetamol (PC) in pharmaceutical formulations using adsorptive stripping differential pulse voltammetry. The GO was prepared from graphite via a modified Hummers’ method and characterized by FTIR and Raman spectroscopy to confirm the presence of oxygen functional groups in the conjugated carbon-based structure whilst, changes in crystalline structure was observed after XRD analysis of graphite and GO.
2023-10-07
8
Nasr, Maryline. "Elaboration of oxides membranes by electrospinning for photocatalytic applications." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT210/document.
Повний текст джерелаАнотація:
De nos jours, les produits chimiques toxiques industriels ne sont pas toujours traités proprement, et leurs contaminants peuvent directement affecter la sécurité de l'eau potable. La photocatalyse, «une technologie verte» est une approche efficace et économique qui joue un rôle important dans la conversion de l'énergie solaire et la dégradation des polluants organiques. Ce manuscrit de thèse rapporte sur le développement des matériaux avancés (basés sur TiO2 et ZnO) susceptibles d'exploiter l'énergie solaire renouvelable pour résoudre les problèmes de pollution environnementale. Une partie de ce travail a été consacrée pour l’amélioration de l’activité photocatalytique du TiO2 sous lumière UV et visible. Par conséquent, les nanofibres composites de rGO/TiO2, BN/TiO2 et BN-Ag/TiO2 ont été élaborées en utilisant la technique d'électrofilage (electrospinning). La deuxième partie porte sur le ZnO, ainsi que les nanotubes multi co-centriques de ZnO/ZnAl2O4 et les nanotubes de ZnO dopés Al2O3 qui ont été synthétisés en combinant les deux techniques : dépôt de couche atomique (ALD) et electrospinning. Les propriétés morphologiques, structurelles et optiques de toutes les nanostructures synthétisées ont été étudiées par différentes techniques de caractérisations. Les résultats ont montré que les propriétés chimiques et physiques ont un effet très important sur les propriétés photocatalytiques des matériaux synthétisés. En outre, il a été constaté que l'effet de dopage conduit à une séparation de charge efficace dans le photocatalyseur, ce qui rend l’activité photocatalytique plus efficace. De plus, le méthyle orange et le bleu de méthylène ont été utilisés comme modèle de référence. Une amélioration significative et une stabilité à long terme de l’activité photocatalytique ont été observées avec les matériaux dopés comparés aux matériaux non-dopés sous lumière UV et visible. Des tests antibactériens contre Escherichia coli ont été également effectués; les résultats indiquent que BN-Ag/TiO2 présente à la fois des propriétés photocatalytiques intéressantes pour la dégradation des composés organiques et pour l'élimination des bactériesNowadays, industrial toxic chemicals are still not properly treated and these contaminants may directly impact the safety of drinking water. Photocatalysis “a green technology” is an effective and economical approach and plays an important role in solar energy conversion and degradation of organic pollutants. This thesis manuscript reports on developing advanced materials (based on TiO2 and ZnO) being capable of exploiting renewable solar energy for solving the environmental pollution problems. A part of this work was dedicated to improve the UV and visible light TiO2 photoresponse. Therefore, rGO/TiO2, BN/TiO2 and BN-Ag/TiO2 composties nanofibers were successfully elaborated using the electrospinning technique. The second part focused on ZnO. Novel structures of ZnO/ZnAl2O4 multi co-centric nanotubes and Al2O3 doped ZnO nanotubes were designed by combining the two techniques of atomic layer deposition (ALD) and electrospinning. The morphological, structural and optical properties of all synthesized nanostructures were investigated by several characterization techniques. The results show that the chemical and physical properties have a high impact on the photocatalytic properties of the synthesized materials. Moreover, it was found that the doping effect lead to a more efficient charge separation in the photocatalyst, which is an advantage for photocatalytic activities. In addition, methyl orange and methylene blue were used as model reference. A significant enhancement and a long-term stability in the photocatalytic activity were observed with the doped materials compared to the non-doped ones under both UV and visible light. Antibacterial tests against Escherichia coli have also been performed; the results indicate that BN-Ag/TiO2 present interesting photocatalytic properties for both organic compound degradation and bacterial removal
9
Dahlberg, Tobias. "The first order Raman spectrum of isotope labelled nitrogen-doped reduced graphene oxide." Thesis, Umeå universitet, Institutionen för fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-116699.
Повний текст джерелаАнотація:
The topic of this thesis is the study of nitrogen functionalities in nitrogen-doped reduced graphene oxide using Raman spectroscopy. Specifically, the project set out to investigate if the Raman active nitrogen-related vibrational modes of graphene can be identified via isotope labelling. Previous studies have used Raman spectroscopy to characterise nitrogen doped graphene, but none has employed the method of isotope labelling to do so. The study was conducted by producing undoped, nitrogen-doped and nitrogen-15-doped reduced graphene oxide and comparing the differences in the first-order Raman spectrum of the samples. Results of this study are inconclusive. However, some indications linking the I band to nitrogen functionalities are found. Also, a hypothetical Raman band denoted I* possibly related to \spt{3} hybridised carbon is introduced in the same spectral area as I. This indication of a separation of the I band into two bands, each dependent on one of these factors could bring clarity to this poorly understood spectral area. As the results of this study are highly speculative, further research is needed to confirm them and the work presented here serves as a preliminary investigation.
10
Arbuzov, A. A., V. E. Muradyan, B. P. Tarasov, and E. A. Sokolov. "Preparation of Amino-Functionalized Graphene Sheets and their Conductive Properties." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35639.
Повний текст джерелаАнотація:
Amino-functionalized graphene sheets were prepared through chemical reduction by hydrazine hy-drate, amination or amidation of graphite oxide. For amination of graphite oxide were used polyamine such as ethylenediamine, diethylenetriamine and triethylenetetramine. Addition of amine groups to graphene is identified by Fourier transform infrared spectroscopy, Raman spectroscopy, elemental analysis and ther-mogravimetry. Scanning electron microscopy data indicate that the organic amine is not only as nitrogen sources to obtain the nitrogen-doped graphene but also as an important modification to control the assem-bly of graphene sheets in the 3D structures. The electrical conductivity of the materials obtained by amina-tion and amidation of graphene is much smaller than that of reduced graphite oxide.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35639
11
Mach, Radoslav. "Vlastnosti grafenoidových vrstev." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377055.
Повний текст джерелаАнотація:
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.
12
Mowry, Michael N. "In situ Raman Spectroscopy Study of the Formation of Graphene from Urea and Graphite Oxide." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/17424.
Повний текст джерелаАнотація:
Approved for public release; distribution is unlimitedGraphene, 10 or fewer atomic layers of carbon atoms, has attracted much attention during recent years due to its unique structure and exceptional physical properties. While there exist a wide range of potential applications, as with many nanomaterials, new synthesis techniques are required that allow for a production of graphene on an industrial scale. In this study, in situ Raman spectroscopy was used to study the formation and doping of graphene during urea-assisted thermal exfoliation of graphite oxide (GO), a promising new synthesis method that can be scaled to industrial levels. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mass spectroscopy were used complementary to Raman spectroscopy to assist with the interpretation of the obtained data. Raman spectroscopy is a powerful characterization tool for the analysis of carbon nanomaterials, such as graphene. While several researchers have reported on the reaction of urea and GO, none of the studies found in literature has provided deeper insights on the evolution of the graphene structure and the simultaneous incorporation of nitrogen into the honeycomb lattice during synthesis. The knowledge gained from this work allows for a better understanding of the graphene production process and provides further evidence for the potential nitrogen-doping of graphene via deposition of urea.
13
Pradhan, Siddharth. "Quantification of Graphene Oxide Structure Using an Improved Model." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342730902.
Повний текст джерела
14
Chu, Hua-Wei. "Development of solution-processed methods for graphene synthesis and device fabrication." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/44738.
Повний текст джерелаАнотація:
Various solution-processed methods have been employed in this work. For the synthesis of graphene, a chemical exfoliation method has been used to generate large graphene flakes in the solution phase. In addition, chemical or electro polymerization has been used for synthesizing polyanthracene, which tends to form graphene nanoribbon through cyclodehydrogenation. For the device fabrication, graphene oxide (GO) thin films were deposited from solution phase on the vapor-silanzed aminosilane surface to make semiconducting active layer or conducting electrodes. Gold nanoparticles (AuNPs) were selectively self-assembled from solution phase to pattern nanowires.
15
Kiryukhin, D. P., Y. M. Shulga, S. A. Baskakov, G. A. Kichigina, P. P. Kushch, and A. Michtchenko. "Low Temperature Post Radiation Polymerization of Tetrafluoroethylene in the Presence of the Graphene 3D Material." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35597.
Повний текст джерелаАнотація:
It was found that irradiation by γ-rays at the liquid nitrogen temperature of a mixture of C2F4 with the grapheme 3D material obtained by explosive exfoliation of graphite oxide gives a composite in which the concentration of polytetrafluoroethylene is 80 wt %. In the case of C2F4 polymerization under similar conditions in the absence of the carbon material, the PTFE yield is six times lower. The results of certifica-tion of both the parent carbon material and the composite obtained via polymerization are also reported.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35597
16
Al, Zohbi Fatima. "Etude de Polyanilines et de nanocomposites Polyaniline/Graphène en milieu liquide ionique protique pour la réalisation de supercondensateurs." Thesis, Tours, 2016. http://www.theses.fr/2016TOUR4026/document.
Повний текст джерелаАнотація:
Les travaux réalisés dans le cadre de cette thèse ont porté sur la réalisation de polymères conducteurs de type polyaniline et de leurs composites associés à du graphène en vue d’une utilisation en tant que matériaux d’électrodes dans des dispositifs de stockage d’énergie de type supercondensateurs. Les travaux se sont tout d’abord orientés sur la synthèse de nouveaux liquides ioniques protiques (LIP) associant des cations pyrrolidinium (Pyrr+) et imidazolium (Imi+) avec des anions p-toluène sulfonate (PTS-), hydrogénosulfate (HSO4-) ou (+)-camphre-10-sulfonate (Cs-), et de l’étude de leur propriétés physico-chimiques (conductivité, viscosité) dans des mélanges binaires LIP/eau. Après avoir déterminé les formulations permettant d’atteindre les propriétés de transport optimales, les capacitances spécifiques de la Pani/HCl dans ces milieux LIP ont été déterminées et nous avons montré que les performances de dispositifs symétriques sont améliorées en capacitance, énergie et en puissance (400 F/g, 7 Wh.kg-1 et 4 kW.kg-1 pour les valeurs les plus élevées) par rapport à un milieu H2SO4 1M. Ces milieux LIP ont également été utilisés comme milieu de synthèse de la Pani. Nous avons ainsi montré que la nature des LIP, qui sont des milieux nanostructurants, pouvait modifier les propriétés électroniques, morphologiques et thermiques des Pani. Un optimum de conductivité électronique de la Pani (22 S/cm) a été atteint avec une synthèse réalisée dans le mélange binaire [Imi][HSO4]/eau 70/30 (pourcentage massique) générant une morphologie fibrillaire et une bonne cyclabilité (93% de rétention de capacitance sur 1000 cycles dans H2SO4 1M. Des valeurs de près de 400 F/g ont été obtenues dans le mélange [Pyrr][HSO4]/eau 41/59 optimisé. Dans le cas de la synthèse de la Pani réalisée dans [Pyrr][PTS]/eau, un gain en stabilité thermique (360°C) est obtenu grâce au dopage par l’anion PTS-. Finalement, une étude exploratoire sur la préparation de composites Pani/graphène et Pani/oxyde de graphène a été réalisée. Les synthèses des nanocomposites ont été effectuées dans les mélanges LIP/eau. L’optimisation de la composition du composite a été étudiée et indique que des rapports massiques de graphène ou oxyde de graphène d’environ 15% permettent d’atteindre des performances de stockage prometteuses et exaltées par rapport à celles obtenues pour des Pani sans graphèneThe work carried out during this PhD thesis is based on the preparation of conducting polymers such as polyaniline (Pani) and their composites associated with graphene for use as electrode materials for supercapacitors application. This work was first dedicated to the synthesis of new protic ionic liquids (PILs) combining pyrrolidinium (Pyrr+) or imidazolium (Imi+) cations with p-toluene sulfonate (PTS-), hydrogen sulfate (HSO4-) or (+)-camphor-10-sulfonate (Cs-) anion, and the study of their physico-chemicals properties (conductivity, viscosity) in binary mixtures PILs/water. After determining the formulations needed to achieve the optimum of transport properties, the specific capacitance of Pani/HCl in these PILs medium was determined, and we have shown that the performance of symmetrical devices are improved in capacitance, specific energy and specific power (400F/g, 7Wh/kg and 4kW/kg for the higher values) in comparison to those obtained in a H2SO4 1M medium. These PILs mediums were also used as a synthesis medium of Pani. We have shown that the nature of PILs, acting as soft template, could change the electronic, morphological and thermal properties of Pani. An optimum of electronic conductivity of Pani (22 S/cm) was obtained with a synthesis realized in the binary mixture [Imi][HSO4]/water 70/30 generating a fibrillar morphology and a good cyclability (93% capacitance retention over 1000 cycles in H2SO4 1M at 2 A/g). For Pani synthesis in [Pyrr][PTS]/water, a thermal stability gain (360 °C) is obtained thanks to a PTS- doped Pani. Finally, a preliminary study on the preparation of composite Pani/graphene and Pani/graphene oxide was performed. The syntheses of nanocomposites were realized in PILs/water mixtures. The optimization of the composition of the Pani nanocomposites was studied and it was found that a mass ratio of about 15% in weight of graphene or graphene oxide enables to obtain promising nanomaterials with higher electrochemical performances compared with pristine Pani
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Tekenya, Ronald. "Graphene-modified pencil graphite mercury-film electrodes for the determination of trace metals by cathodic adsorptive stripping voltammetry." University of the Western Cape, 2018. http://hdl.handle.net/11394/6552.
Повний текст джерелаАнотація:
>Magister Scientiae - MScThis project focuses on the simple, fast and highly sensitive adsorptive stripping voltammetry detection of Nickel and Cobalt complexed with DMG and Nioxime respectively at a Reduced Graphene Oxide modified pencil graphite electrode in water samples. This research as well demonstrates a novel electrochemically reduced graphene oxide (ERGO)/mercury film (MF) nanocomposite modified PGE, prepared through successive electrochemical reduction of graphene oxide (GO) sheets and in-situ plated mercury film. The GO and graphene were characterized using FT-IR, HR-SEM, HR-TEM, XRD and Raman spectroscopy. The FT-IR results supported by Xray diffraction analysis confirmed the inclusion of oxygen moieties within the graphitic structure during the chemical oxidation step. Microscopic and spectroscopic analysis was used to confirm the stackings of graphene on the pencil electrode. The ERGO-PG-MFE, in combination with a complexing agents of [dimethylglyoxime (DMG) and Nioxime] and square-wave cathodic stripping voltammetry (SW-CSV), was evaluated towards the individual determination of Ni2+ and Co2+ respectively and simultaneous determination of both metals from the combination of DMG and Nioxime mixture. A single-step electrode pre-concentration approach was employed for the in-situ Hg-film electroplating, metal-chelate complex formation and its non-electrolytic adsorption at – 0.7 V for the individual analysis of Ni2+ and Co2+. The current response due to metal-ligand(s) complex reduction were studied as a function of experimental variables; deposition/accumulation potential, deposition/accumulation time, rotation speed, frequency and amplitude and carefully optimized for the individual determination of Ni2+and Co2+ and simultaneous determination of Ni2+ and Co2+ at low concentration levels (μg L-1) in 0.1 M NH3- NH4Cl buffer solution (pH 9.4) solution. The recorded limit of detection for the individual analysis of Ni2+and Co2+ was found to be 0.120 μg L-1 and 0.220 μg L-1 respectively, at an accumulation time of 120 s for both metals. The recorded limit of detection of the simultaneous analysis of Ni2+ and Co2+ was found to be 6.1 μg L-1 and 1.8 μg L-1 respectively. The ERGO-PG-MFE further demonstrated a highly selective stripping response toward all trace metal analysis. The testing of the applicability of graphene-based sensor and method in laboratory tap water samples was evaluated. This electrode was found to be sensitive enough to detect metal ions in the tap water samples at the 0.2 μg L-1 level for individual analysis and 0.001 μg L-1 for simultaneous, well below WHO standards.
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Huang, Xianjun. "Electromagnetic applications of graphene and graphene oxide." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/electromagnetic-applications-of-graphene-and-graphene-oxide(873c9618-19a3-4818-b47a-9afbca39857c).html.
Повний текст джерелаАнотація:
Since the isolation of graphene in 2004, a large amount of research has been directed at 2D materials and their applications due to their unique characteristics. This thesis delivers pioneering developments on the applications of graphene and graphene oxide (GO) on electromagnetic ranges such as radio frequency, microwave frequency and THz bands, and specifically 2D materials based antennas, absorbers, sensors and etc. This thesis focuses on exploring electromagnetic applications of monolayer graphene, printed graphene and graphene oxide. In study of monolayer graphene applications, the theoretical and simulation studies are carried out to design tunable terahertz (THz) absorbers, tunable microwave wideband absorbers, and reconfigurable antennas, etc. These studies on the applications of monolayer graphene have proved prospective potentials of graphene in THz sensing, RCS reduction, and reconfigurable antennas. This thesis also presents pioneering advances on electromagnetic applications of printed graphene. Among these works, low-cost highly conductive and mechanically flexible printed graphene is developed for radio frequency (RF) applications. For the first time, effective RF radiation of printed graphene is experimentally demonstrated. Based on these results, applications of printed graphene including RFID (radio frequency identification) tags, anti-tampering RFID, EMI shielding, flexible microwave components such as transmission lines, resonators and antennas, conformable wideband radar absorbers, graphene oxide based wireless sensors, etc. are developed and experimentally demonstrated. This work significantly expands applications of graphene in electromagnetic areas.
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Hamandi, Marwa. "Élaboration et caractérisation d’oxydes de Titane de Morphologie Contrôlée : application à la Photodégradation de Polluants Organiques." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1077/document.
Повний текст джерелаАнотація:
Ce travail se résume en deux objectifs principaux. Le premier concerne l'élaboration de matériaux nanohybrides de dioxyde de titane (sous forme sphérique ou tubulaire) décoré par des allotropes de carbone (fullerène fonctionnalisé ou graphène). Le deuxième objectif consiste à l'évaluation de ces différents nanomatériaux dans la photodégradation de l'acide formique (AF) sous irradiation UV. Un effet bénéfique des allotropes de carbone sur l'activité photocatalytique des nanohybrides a été observé suite à l'augmentation de la durée de vie des paires électron-trou photogénérées. Dans un premier temps, la méthode d'élaboration et la teneur en fullerène fonctionnalisé ont été optimisées conduisant ainsi à l'élaboration de nanomatériaux révélant des propriétés photocatalytiques améliorées par rapport au TiO2 nanotube seul. Une corrélation entre les propriétés texturales, les propriétés photoélectriques et la constante de vitesse de dégradation de l'AF a été établie afin d'élucider les causes de l'amélioration de l'activité photocatalytique. Dans un second temps, une étude détaillée portant sur l'élaboration d'une nouvelle génération de nanocomposites combinant nanotubes de TiO2 et oxyde de graphène (OG) a été menée. Le degré de réduction de l'oxyde de graphène influence fortement l'activité photocatalytique. Ainsi, l'addition d'OG ou OG réduit aux nanotubes de TiO2 influence positivement les performances intrinsèques en photodégradation de l'acide formique en facilitant le transfert de photoélectrons de la bande de conduction du TiO2 vers l'oxyde de graphène. Finalement, l'étude des matériaux composites combinant l'oxyde de graphène et diverses compositions anatase/rutile a permis de mettre en évidence une synergie entre le OG et les deux phases TiO2Two main objectives were achieved in the present work. The first objective concerns the elaboration of nanohybrid materials formed by combining titanium dioxide (in spherical or tubular form) with carbon allotropes (functionalized fullerene or graphene). The second objective consists in evaluating these different nanomaterials in the photodegradation of formic acid (FA) under UV irradiation. A beneficial effect of the different carbon allotropes on the photocatalytic activity of the resulting nanohybrids was observed and ascribed to an increased lifetime of photogenerated electron-hole pairs. In a first step, the elaboration method of functionalized fullerenes and their content were optimized leading to the development of nanomaterials showing improved photocatalytic properties compared to TiO2 nanotube alone. Textural properties, photoelectric properties and the FA degradation rate constant were correlated in order to determine the reasons for the photocatalytic activity improvement. In a second step, a detailed study about the development of a new generation of nanocomposites combining TiO2 nanotubes and graphene oxide (GO) was carried out. The degree of reduction of GO strongly influences the photocatalytic activity. Thus, the addition of reduced GO or GO to TiO2 nanotubes improves the intrinsic photodegradation performance of formic acid by facilitating the transfer of photoelectrons from the conduction band of TiO2 to graphene oxide. Finally, composite materials combining graphene oxide and various anatase/rutile compositions were analyzed showing a synergy between GO and the two TiO2 phases
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Guimont, Aline. "Greffage de polydimethylsiloxane et de polyéthylène sur des feuillets de graphène oxydé : application à la synthèse de (nano)composites conducteurs." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10028/document.
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L'objectif de la thèse est d'expérimenter et de valider de nouvelles voies d'exfoliation des feuillets de graphène dans des élastomères de type silicone (PDMS) et des thermoplastiques de type polyéthylène (PE). Ce projet s'appuie sur des étapes de modifications chimiques des feuillets de graphite oxydé (GO) dont la polarité initiale n'offre pas une compatibilité satisfaisante avec les matrices étudiées. Différentes approches ont été explorées : la synthèse du GO greffé PDMS a été réalisée avec succès par greffage directe d'un PDMS fonctionnalisé triéthoxysilane et par une réaction d'hydrosilylation catalytique de GO modifiés vinyltriméthoxysilane en présence de polyméthylhydrogénosiloxane. Une étude des propriétés viscoélastiques de suspensions de GO et GO modifié/PDMS a montré l'importance de l'interaction charge-charge sur la formation d'un réseau percolant. Le seuil de percolation rhéologique du GO a été obtenu à 1,75 %wt avec Af~60. En se basant sur le greffage radicalaire du pentadécane par abstraction d'atomes d'H par un peroxyde à haute température, il a été possible d'extrapoler cette réaction pour procéder au greffage d'un PE de faible masse molaire (Mn~2000). De plus, des PE fonctionnalisés thiol et azoture de Mn similaire ont aussi été greffés sur des dérivés du graphite par addition radicalaire et de Michael. Après sélection d'une charge présentant une conductivité en poudre proche du graphite et une bonne affinité pour les milieux alcanes, un nano-composite à base de PEBD présentant des propriétés électriques convenables pour une application de blindage électromagnétique (4.105 Ω.cm à 25%wt) a été réalisé et ceci sans utiliser d'agents réducteurs toxiquesThe aim of this thesis was to experiment and validate new means of graphene exfoliation in an elastomer matrix such as silicone (PDMS) and a thermoplastic matrix such as polyethylene (PE). Because of the low affinity of graphene oxide for these matrices due to its high polarity, its chemical modification was carried out. Different approaches were explored: the grafting of PDMS onto GO was carried out with success by a direct functionalization with a PDMS terminated triethoxysilane and by a catalytic hydrosilation reaction of a PDMS terminated Si-H onto vinyltrimethoxysilane modified GO. The viscoelastic behavior of GO and modified GO/PDMS suspensions showed the importance of the filler-filler interaction on the formation of a percolating network. The rheological percolation threshold of the GO/PDMS suspension was obtained at ~1.75 wt% with an aspect ratio (Af) of ~60. In addition, the grafting of PE onto GO was studied with the high temperature radical grafting of pentadecane formed by a hydrogen atom abstraction with a peroxide, which was then extrapolated to a low molecular PE (Mn~2000). Moreover, thio and azide functionnalized PE with a similar Mn were also grafted onto graphite derivatives by a radical and a Michael addition. After choosing the filler which presented the closest electrical conductivity to the one of graphite powder and a good affinity for a heptane media, a LDPE based nano-composite that presented suitable electrical properties for an electromagnetic shielding application (4 105 Ω.cm at 25 wt%) was obtained and this without any use of toxic reducing agents
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Roman, Julien. "Mise en forme de matériaux carbonés biosourcés par voie liquide." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0202/document.
Повний текст джерелаАнотація:
Ce travail de thèse est consacré à la mise en forme de nouveaux matériaux carbonés à partir d’un précurseur biosourcé. Les matériaux carbonés tels que les fibres de carbone utilisés dans les composites sont principalement obtenus à partir de précurseurs d’origine pétrosourcée. Ces précurseurs sont onéreux et incompatibles avec une industrie durable. L’utilisation d’un précurseur biosourcé disponible en grande quantité tel que la lignine permet de pallier ces limitations. La structure moléculaire aromatique et la teneur élevée en carbone de la lignine font d’elle un candidat idéal pour l’élaboration de matériau carboné biosourcé. La lignine a pu être transformée en divers matériaux carbonés tels que des nanofibres de carbone, des tresses de nanofibres de carbone, ou encore des objets 3D composites carbonisés. Ces matériaux ont été obtenus à partir de techniques innovantes que sont l’électrofilage et l’impression 3D. Le tressage des nanofibres de carbone ex-lignine a permis d’évaluer les propriétés mécaniques des fibres de carbone. Les propriétés électrochimiques des tresses de nanofibres de carbone ex-lignine sont apparues intéressantes pour une utilisation potentielle en tant que microélectrodes. La microstructure faiblement organisée du carbone issue de la lignine a pu être améliorée. Un traitement thermique de graphitisation ou un ajout de nanocharges carbonées ont contribué à cette amélioration. Les propriétés mécaniques, structurales et de conductivité électrique des nanofibres nanocomposites ont permis de définir l’influence de l’oxyde de graphène sur la lignine. Un effet composite entre ces deux constituants a pu être observé. L’impression 3D d’encres composites à base de lignine et d’oxyde de graphène a pu être rapportée pour la première fois afin d’élaborer des objets 3D carbonisés denses, organisés et conducteurs d’électricitéThis work is devoted to the preparation of new bio-based carbon materials. Carbon materials, such as carbon fibers used in composites, are mainly obtained from a petroleum precursor. These precursors are expensive and not compatible with a sustainable industry. The use of a bio-based precursor available in large quantities such as lignin makes it possible to overcome limitations of petroleum based precursors. The aromatic molecular structure and high carbon content of lignin make it an ideal candidate for the production of bio-based carbon material. Lignin could be transformed into various materials such as carbon nanofibers, twisted carbon nanofibers, or carbonized composite 3D structures. These materials have been obtained from innovative techniques such as electrospinning and 3D printing. Twisting of the lignin-based-carbon nanofibers allowed for measurements of their mechanical strength. The electrochemical properties of the lignin-based twisted carbon nanofibers are interesting for potential microelectrode applications. The low microstructural order of the carbon from the carbonized lignin has been improved. Graphitization treatment or addition of carbon nanofillers contributed to this improvement. The mechanical, structural and electrical properties of nanocomposite carbon nanofibers illustrate the influence of graphene oxide on lignin. A composite effect between these two components has been observed. The 3D printing of composite inks based on lignin and graphene oxide has been reported for the first time in order to elaborate dense, organized and electrically conductive 3D carbonized structures
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Paulauskas, Mindaugas. "Pervaporation using graphene oxide membranes." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/12282/.
Повний текст джерелаАнотація:
Pervaporation is a perspective fluid separation technology. Membranes are widely recognised for their energy and capital cost savings. Currently, most of the research is focused on developing new membrane material that are stable in a wide range of temperatures in a presence of organic solvents. This research is focused on a graphene oxide, a novel and highly selective membrane material. Graphene oxide has attracted a lot of academic research attention. Many researchers have demonstrated selective water removal using this material, however moving forward the data lack the scope and depth of understanding of the material performance at different process conditions and fluid systems. Previous research has not addressed graphene oxide stability and performance in a wide range of conditions which are crucial for assessing the material’s potential as a water selective membrane material for industrial applications. The purpose of this work is to investigate graphene oxide membrane pervaporation permeation flux and selectivity using common aqueous organic solvent solutions. Three industrial case studies are also investigated to determine whether the material is ready to be applied on a larger scale and has a potential to replace distillation. Previous research has also missed graphene oxide low price advantage, which stems from the cheap starting materials. This has been brought up and discussed in the final results chapter of the thesis. The key outcome of this research is a demonstration of the graphene oxide pervaporation flux drop at elevated temperatures and the behaviour deviation from the solution-diffusion model. The membrane has also been rapidly fouled when exposed to aqueous peptide solutions. This research brings a large amount of experimental and analytical data, which points in a direction of the research avenues to be pursued in order to improve graphene oxide as a selective membrane material.
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Jankus, Daniel James. "Antimicrobial Properties of Graphite and Coal-Derived Graphene Oxides as an Advanced Coating for Titanium Implants." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103151.
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Prosthetic joint infection (PJI) poses a significant risk to implanted patients, requiring multiple surgeries with high rates of reinfection. The primary cause of such infections is otherwise innocuous bacterial species present on the skin that have survived sterilization protocols. Antibiotic drugs have significantly reduced efficacy due to the lack of vasculature in the newly implanted site, allowing microbes to form biofilms with even greater resistance. Graphene oxide (GO) is known to have good biocompatibility while providing drugless antimicrobial properties. The focus of this study is on the development and characterization of a robust coating for titanium alloy implants to promote bone regeneration while inhibiting microbial biofilm adhesion to the implant surface. The novelty of this study is the use of proprietary coal-derived graphene oxide (c-GO) in a biomedical application. c-GO has been demonstrated to have a greater number of functional oxygen groups to promote cell adhesion, while also maintaining thinner layers than possible with graphite exfoliation methods. As an alternative to powerful antimicrobial drugs, it was hypothesized that an advanced coating of graphene-oxide would provide a defensive, passively antimicrobial layer to a titanium implant. While GO is typically quite expensive, the newly developed process provides an economical and environmentally friendly method of producing GO from coal (c-GO). The result is a coating that is inexpensive and capable of halving the biofilm formation of MRSA on titanium-alloy surgical screws in addition to providing improved bone cell adhesion and hard tissue compatibility.Master of Science
Any time a patient receives implantation surgery, there is a chance of microbes entering the body. These are typically naturally occurring skin flora, harmless but opportunistic. On the surface of implants within the body, these bacteria can form colonies called biofilms, leading to severe and potentially deadly infections, called prosthetic joint infection (PJI). PJI often requires multiple surgeries to remedy, but rates of reinfection are relatively high. As with any surgery, patients are given antibiotic drugs, but implants to not receive blood flow as the body normally would, reducing the effectiveness of antibiotics. Once biofilms are formed, the bacteria become even hardier and resistant even to powerful antibiotics. Graphene oxide (GO) is a carbon material known to have good biocompatibility (i.e., non-toxic) while providing antimicrobial properties. The focus of this study is on the development and characterization of a robust coating for titanium alloy implants to promote bone healing while reducing microbial biofilm colonization on the implant's surface. The novelty of this study is the use of proprietary coal-derived graphene oxide (c-GO) in a biomedical application. c-GO has been demonstrated to have a different chemical makeup than graphite-derived GO, which may improve its efficacy as an antimicrobial coating. As an alternative to powerful antimicrobial drugs, it was hypothesized that a coating of graphene-oxide would provide a defensive, passively antimicrobial layer to a titanium implant. While GO is typically quite expensive, the newly developed one-pot process provides an economical and environmentally friendly method of producing GO from coal (c-GO). The result is a coating that is inexpensive and capable of halving the biofilm formation of MRSA on titanium-alloy surgical screws in addition to providing improved bone cell adhesion and hard tissue compatibility.
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Lee, Dongwook. "The structure and magnetism of graphite oxide." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611649.
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Lagier, Laura. "Ecotoxicité comparative de l'oxyde de graphène et d'autres nanoparticules de carbone chez des organismes aquatiques modèles : d'une évaluation en conditions monospécifiques vers l'étude d'une chaîne trophique expérimentale." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30270/document.
Повний текст джерелаАнотація:
L'écotoxicité de différentes nanoparticules de carbone (NPC) a été évaluée chez des organismes aquatiques, en particulier chez Xenopus laevis. Il a été montré que la surface des NPC est le paramètre le plus pertinent pour décrire l'inhibition de croissance chez le xénope, indépendamment de leur forme allotropique et de leur état de dispersion. L'induction des micronoyaux a aussi été étudiée chez le xénope, et l'oxyde de graphène (GO) s'est révélé génotoxique à faible dose, résultat corroboré par l'étude de l'expression des gènes. Les mécanismes de toxicité impliqués seraient notamment liés aux fonctions oxygénées de la particule. De plus, le GO a aussi entrainé de la génotoxicité chez Pleurodeles waltl. et de la tératogénicité, des retards de développement et de l'inhibition de croissance chez Chironomus riparius. La mise en interaction de ces organismes au sein d'un mésocosme a également conduit à l'observation de génotoxicité chez le pleurodèle en présence de GOThe ecotoxicity of different carbon-based nanoparticles (CNPs) was assessed in freshwater organisms, especially in Xenopus laevis. The surface of the CNPs was shown to be the more relevant parameter to describe the growth inhibition in Xenopus, regardless of their allotropic form and their state of dispersion. Micronucleus induction was also studied in Xenopus and graphene oxide (GO) was found genotoxic at low dose. This result was in compliance with the study of genes expression. The involved toxicity mechanisms would be related to the oxidized functions of the CNP. Moreover, GO was also found responsible for genotoxicity in Pleurodeles waltl. and for teratogenicity, development delay and growth inhibition in Chironomus riparius. These organisms have finally been put together in a mesocosm, which has also led to genotoxicity in Pleurodeles in the presence of GO
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Moraes, Ana Carolina Mazarin de 1983. "Graphene oxide and graphene oxide functionalized with silver nanoparticles : antibacterial activity and polymeric composites applications." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249034.
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Orientador: Oswaldo Luiz AlvesTese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: O óxido de grafeno (GO) é uma forma quimicamente modificada de grafeno que possui grupos funcionais contendo oxigênio (epóxi, carboxila, carbonila, e hidroxila) distribuídos sobre a base e as bordas de suas folhas. Devido à abundância dos grupamentos oxigenados, o GO tem sido usado como uma plataforma para suportar e estabilizar nanoestruturas metálicas, tais como nanopartículas de prata (NPAgs), visando aplicações biológicas. Além disso, devido à sua excelente capacidade de dispersão e elevada área superficial, o GO tem sido considerado uma carga promissora para a construção de compósitos poliméricos. Neste trabalho, relatamos a síntese do GO e dos nanocompósitos de óxido de grafeno funcionalizado com NPAgs (GO-Ag) os quais podem ser utilizados como agentes antibacterianos de amplo espectro. O GO foi sintetizado por meio do método de Hummers modificado, e o GO-Ag foi preparado através da redução in situ dos íons de prata por citrato de sódio. As folhas de GO foram funcionalizadas com NPAgs esféricas de diâmetro médio de 9,4 nm. Estes nanocompósitos exibiram excelente atividade antimicrobiana contra as principais bactérias em ambiente hospitalar, tais como Escherichia coli, Enterococcus faecalis, Acinetobacter baumannii, e Staphylococcus aureus resistente à meticilina. Os nanocompósitos GO-Ag também foram aplicados como eficazes agentes antimicrobianos a fim de evitar a proliferação bacteriana em membranas de micro e ultrafiltração. Neste sentido, membranas antimicrobianas de acetato de celulose (CA) foram fabricadas a partir da incorporação de GO e GO-Ag na matriz polimérica (CA-GOAg). Após a funcionalização, as membranas permeáveis modificadas com GO-Ag foram capazes de inativar cerca de 90% das células de E. coli em comparação com as membranas de CA não modificadas. Os resultados sugerem que a incorporação de nanocompósitos GO-Ag é uma abordagem promissora para controlar o desenvolvimento da adesão bacteriana em membranas de purificação de água. Com relação à demanda de novos materiais com elevada estabilidade e com capacidade de proteção contra radiação ultravioleta (UV), foram fabricados filmes compósitos transparentes a partir de acetato de celulose e óxido de grafeno. A caracterização físico-química revelou que as folhas de GO estão bem dispersas por toda a matriz polimérica, proporcionando filmes compósitos lisos e homogêneos. Em comparação com os filmes pristinos de CA, os filmes compósitos exibiram melhor capacidade de proteção contra radiação UV combinado com transparência óptica à luz visível, o que reforça a sua aplicação como revestimentos transparentes com proteção UV para alimentos, produtos farmacêuticos, biomédicos, e produtos eletrônicos
Abstract: Graphene oxide (GO) is a chemically modified form of graphene that possesses oxygen-containing groups (epoxy, carboxyl, carbonyl, and hydroxyl) distributed on the plane and edges of the sheets. Owing to the abundance of oxygenated groups, GO has been used as a platform to support and stabilize metallic nanostructures such as silver nanoparticles (AgNPs), aiming biological applications. In addition, GO has been considered a promising material for building polymeric composites because of its excellent dispersibility and high surface area. In this work, we report the synthesis of GO and GO functionalized with AgNPs (GO-Ag) for use as a broad-spectrum antibacterial agent. GO was synthesized through the modified Hummers method, and the GO-Ag was prepared through the in situ reduction of silver ions by sodium citrate. Spherical AgNPs with average size of 9.4 nm were found well-dispersed throughout the GO sheets. This nanocomposite exhibited excellent antimicrobial activity against common nosocomial bacteria such as Escherichia coli, Enterococcus faecalis, Acinetobacter baumannii, and methicillin-resistant Staphylococcus aureus. GO-Ag nanocomposites were also applied as an effective antimicrobial agent in order to prevent the bacterial proliferation on micro and ultrafiltration membranes. Cellulose acetate (CA) membranes were then fabricated from the incorporation of GO and GO-Ag into the polymeric matrix (CA-GOAg). After functionalization, the permeable CA membranes modified with GO-Ag were able to inactivate mostly 90% of E. coli cells compared to the non-modified CA membranes. The results suggest that the incorporation of GO-Ag nanocomposites is a promising approach to control biofouling development in water purification membranes. Concerning the demand for novel ultraviolet shielding materials with high stability, transparent and UV-shielding composite films were fabricated by casting a mixture of GO with cellulose acetate (CA). The physicochemical characterization revealed that GO sheets were well-dispersed throughout the polymeric matrix, providing smooth and homogeneous composite films. By comparison with pristine CA films, the composite films displayed an improved UV-shielding capacity combined with optical transparency under visible light, which underscores their application as transparent UV-protective coatings for food, pharmaceutical, biomedical, and electronic products
Doutorado
Quimica Inorganica
Doutora em Ciências
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Bourourou, Mariem. "Conception des bioélectrodes enzymatiques à base de nanomatériaux dans des piles à combustible et des capteurs." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI043/document.
Повний текст джерелаАнотація:
Le travail présenté dans ce manuscrit est une contribution à la recherche sur la mise en forme d'une nouvelle classe de bioélectrodes nanostructurées, principalement à base de nanotubes de carbone (NTCs). L'oxyde de graphène (GO) a été également évalué pour des applications bioélectrochimiques. Les procédés de fabrication développés autorisent l'ajout d'additifs tels que des médiateurs et des polymères. L'optimisation de la connexion enzymatique de la laccase pour la réduction de l'O2 sur des matrices de nanotubes de carbone ainsi que de la polyphénol oxydase (PPO) pour la détection électrochimique de l'ortho-quinone généré enzymatiquement a été étudiée. Dans un premier temps, le transfert d'électrons direct avec la laccase a été optimisé dans une matrice nanostructurée de NTCs. Dans ce contexte, nous avons examiné plusieurs approches pour immobiliser la laccase tout en l'orientant grâce à l'utilisation de dérivés de l'anthraquinone afin d'améliorer les performances catalytiques de la biocathode. L'immobilisation et l'orientation de l'enzyme ont été réalisées par fonctionnalisation des électrodes par le pyrène-mono-anthraquinone et le pyrène-bis-anthraquinone. La seconde partie présente la préparation d'une autre cathode basée sur la connexion indirecte de la laccase à une matrice nanostructurée de NTCs (buckypaper) contenant du bis-pyrène-ABTS comme médiateur rédox et comme réticulant pour la stabilité mécanique améliorée de ce buckypaper. La dernière partie de ce travail a été consacrée à la production de fibres par filage électrostatique à partir de deux mélanges différents: NTCs/ PAN(polyacrylonitrile) et GO/PAN. De telles fibres ont été utilisées comme électrodes pour des applications bioanalytiques et la bioconversion d'énergieThis thesis is devoted to the development of a new class of freestanding nanostructured bioelectrodes mainly based on carbon nanotubes (CNTs) Graphene oxide (GO) was also evaluated for its appropriateness for the treated bioelectrochemical approaches. The developed manufacturing processes forming CNTs slides (Buckypapers) or electrospun tissues also allow the confinement with additives like mediators or polymers. The optimization of the enzymatic connection of laccase, for O2 reduction on carbon nanotube arrays, and the polyphenol oxidase (PPO) for the electrochemical detection of enzymatically generated electroactive ortho-quinone was studied. Initially, direct electron transfer of laccase is optimized in a nanostructured CNTs matrix. We examined several approaches to immobilize and orient the laccase using anthraquinone derivatives while improving the catalytic performance of the biocathode. These immobilisation and orientation strategies on electrodes are performed by functionalization using pyrene-mono-Anthraquinone and pyrene-bis-anthraquinone. The second part of this thesis shows the preparation of another biocathode based on the indirect connection of laccase in nanostructured CNT buckypapers containing bis-pyrene-ABTS as a redox mediator and cross-linker, enhancing the mechanic stability of the buckypaper. The last part of this work was devoted to the production of nanofibers by electrospinning from two different blends: CNT / PAN and GO / PAN. Such fiber electrodes were used as bioelectrodes for bioanalytical applications and biological energy conversion
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Ghaffari, Nastaran. "Electrochemical deposition of Graphene Oxide- metal nano-composite on Pencil-Graphite Electrode for the high sensitivity detection of Bisphenol A by Adsorptive Stripping Differential Pulse Voltammetry." University of the Western Cape, 2018. http://hdl.handle.net/11394/6336.
Повний текст джерелаАнотація:
Magister Scientiae - MSc (Chemistry)Electrochemical platforms were developed based on pencil graphite electrodes (PGEs) modified electrochemically with reduced graphene oxide metal nanoparticles (ERGO–metalNPs) composite and used for the high-sensitivity determination of Bisphenol A (BPA) in water samples. Synergistic effects of both reduced Graphene Oxide sheets and metal nanoparticles on the performance of the pencil graphite electrode (PGE) were demonstrated in the oxidation of BPA by differential pulse voltammetry (DPV). A solution of graphene oxide (GO) 1 mg mL-1 and 15 ppm of metal stock solutions (1,000 mg L-1, atomic absorption standard solution) (Antimony or Gold) was prepared and after sonication deposited onto pencil graphite electrodes by cyclic voltammetry reduction. Different characterization techniques such as FT-IR, HR-SEM, XRD and Raman spectroscopy were used to characterize the GO and ERGO–metalNPs. Parameters that influence the electroanalytical response of the ERGO–SbNPs and ERGO–AuNPs such as, pH, deposition time, deposition potential, purging time were investigated and optimized. Well-defined, reproducible peaks with detection limits of 0.0125 μM and 0.062 μM were obtained for BPA using ERGO–SbNPs and ERGO–AuNPs respectively. The rGO-metalNPs–PGE was used for the quantification of BPA in tap water sample and proved to be suitable for the detection of BPA below USEPA prescribed drinking water standards of 0.087 μM.
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Liu, Shizhen. "Graphene oxide and graphene based catalysts in photochemical ractions." Thesis, Curtin University, 2013. http://hdl.handle.net/20.500.11937/882.
Повний текст джерелаАнотація:
Graphene has impressible absorbing ability and its electron transmission capacity makes it a great prosperity in many science horizons. In this study graphene or graphite nitride has been employed as a carrier in order to modify TiO2, ZnO and Ta2O5 photocatalysts.Graphene modified TiO2 particles were obtained by a sol-gel method from titanium isoproproxide (or P25) and reduced graphene oxide (RGO). The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), UV-vis diffuse reflectance (UV-vis DRS) and thermo gravimetric differential thermal analysis (TG-DTA) were investigated over the samples. The diffuse reflectance spectra (DRS) studies indicate that G-TiO2 has a significant light absorption increasing and red shift of absorption peak. G-TiO2 photocatalyst could decompose methylene blue under visible light (> 430 nm). G-TiO2 synthesised from titanium isoproproxide presented better activity than G-TiO2 (P25). The catalysts could also produce ●OH and [O2]- radicals via electron scavengers (peroxymonosulphate, peroxydisulphate and hydrogen peroxide) to enhance degradation process with visible illumination.ZnO loaded RGO photocatalysts were synthesized through Zn powder and graphite oxide. The structural, morphological, and physicochemical properties of the samples were thoroughly investigated by XRD, FT-IR, FE-SEM, UV-visible DRS, TG-DTA, and Raman spectroscopy. Zn powder could successfully reduce GO and ZnO was obtained simultaneously by one-step hydrothermal method. RGO-ZnO photocatalysts could bleach MB under UV-vis illumination.Three different compounds: ammonia, graphene and C3N4 were utilized to dope tantalum pentoxide photocatalyst. Catalysts were analyzed by X-ray diffraction, UV–vis diffuse reflectance spectra and FTIR spectroscopy. The photocatalytic behavior was thorough investigated in bleaching methylene blue under UV-visible illuminations; the modified catalysts could decompose methylene blue, showing better activity than undoped Ta2O5. However, only N-doped Ta2O5 will show activity under visible light.
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Vacchi, Isabella Anna. "Controlled chemical functionalization of graphene oxide." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF053.
Повний текст джерелаАнотація:
L’oxyde de graphène est un nanomatériau prometteur grâce à ses caractéristiques physicochimiques. Cependant, jusqu’à aujourd’hui, sa composition exacte reste encore inconnue. Ceci est dû à la complexité et au caractère non-stoechiométrique de ce matériau. Nous avons commencé par étudier sa composition de surface et sa réactivité. Nous avons utilisé des échantillons synthétisés de manière différente pour explorer la relation entre la méthode de synthèse et la composition de surface. En outre, nous avons préparé un dérivé fonctionnalisé avec un agent chélatant de radionucléides pour étudier sa biodistribution et l’impact de la taille latérale.Par la suite, nous avons essayé plusieurs stratégies de multi-fonctionnalisation. L’avantage est de pouvoir combiner différentes propriétés. Nous avons observé que, souvent après la fonctionnalisation, la dispersabilité de l’oxyde de graphène diminue. Ainsi, nous avons développé un échantillon fonctionnalisé par un polymère soluble dans l’eau. Enfin, nous avons exploré et amélioré les méthodes de caractérisation de l’oxyde de graphène. Une caractérisation approfondie par différentes techniques est fondamentale pour comprendre les modifications que le matériau a subiesGraphene oxide is a promising nanomaterial thanks to its physicochemical characteristics. However, until today its exact composition remains still unknown. This is due to the complexity and non-stoichiometric character of this material.We started by investigating the surface composition of graphene oxide and its reactivity. We used differently synthesized samples to explore the relationship between the synthesis method and the surface composition. Furthermore, we functionalized graphene oxide with a chelating agent of radionuclides to study its biodistribution, and the impact of the lateral size. Afterwards, we tried different strategies for multifunctionalization with the aim to combine different properties. We observed that the dispersibility of graphene oxide often decreased after functionalization. Thus, we developed a highly water-stable graphene oxide sample by grafting awater-soluble polymer on its surface. Finally, we explored and improved the characterization methods for graphene oxide. Athorough investigation using different characterization techniques is fundamental to understand the modifications that the material underwent
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Adewole, Murthada Oladele. "Electrically Tunable Absorption and Perfect Absorption Using Aluminum Doped Zinc Oxide and Graphene Sandwiched in Oxides." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc1404566/.
Повний текст джерелаАнотація:
Understanding the fundamental physics in light absorption and perfect light absorption is vital for device applications in detector, sensor, solar energy harvesting and imaging. In this research study, a large area fabrication of Al-doped ZnO/Al2O3/graphene/Al2O3/gold/silicon device was enabled by a spin-processable hydrophilic mono-layer graphene oxide. In contrast to the optical properties of noble metals, which cannot be tuned or changed, the permittivity of transparent metal oxides, such as Al-doped ZnO and indium tin oxide, are tunable. Their optical properties can be adjusted via doping or tuned electrically through carrier accumulation and depletion, providing great advantages for designing tunable photonic devices or realizing perfect absorption. A significant shift of Raman frequency up to 360 cm-1 was observed from graphene in the fabricated device reported in this work. The absorption from the device was tunable with a negative voltage applied on the Al-doped ZnO side. The generated absorption change was sustainable when the voltage was off and erasable when a positive voltage was applied. The reflection change was explained by the Fermi level change in graphene. The sustainability of tuned optical property in graphene can lead to a design of device with less power consumption.
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Adewole, Murthada Oladele. "Electrically Tunable Absorption and Perfect Absorption Using Aluminum-Doped Zinc Oxide and Graphene Sandwiched in Oxides." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1404566/.
Повний текст джерелаАнотація:
Understanding the fundamental physics in light absorption and perfect light absorption is vital for device applications in detector, sensor, solar energy harvesting and imaging. In this research study, a large area fabrication of Al-doped ZnO/Al2O3/graphene/Al2O3/gold/silicon device was enabled by a spin-processable hydrophilic mono-layer graphene oxide. In contrast to the optical properties of noble metals, which cannot be tuned or changed, the permittivity of transparent metal oxides, such as Al-doped ZnO and indium tin oxide, are tunable. Their optical properties can be adjusted via doping or tuned electrically through carrier accumulation and depletion, providing great advantages for designing tunable photonic devices or realizing perfect absorption. A significant shift of Raman frequency up to 360 cm-1 was observed from graphene in the fabricated device reported in this work. The absorption from the device was tunable with a negative voltage applied on the Al-doped ZnO side. The generated absorption change was sustainable when the voltage was off and erasable when a positive voltage was applied. The reflection change was explained by the Fermi level change in graphene. The sustainability of tuned optical property in graphene can lead to a design of device with less power consumption.
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Watson, Venroy George. "Decoration of Graphene Oxide with Silver Nanoparticles and Controlling the Silver Nanoparticle Loading on Graphene Oxide." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1396879714.
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Liu, Hao. "Modified thermal reduction of graphene oxide." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14024/.
Повний текст джерелаАнотація:
As a strictly two-dimensional carbon material, graphene has attracted great interest in recent years due to its unique mechanical, electrical and optical properties. Currently, the principal methods for mass production of graphene are focused on the solution-based chemical redox reaction. The oxidation of graphite introduces a large amount of oxygen functional groups attached onto its basal plane or edges, which makes graphene oxide (GO) sheets hydrophilic to form stable aqueous colloids. However, the raw material graphite gradually becomes an insulator during the oxidation process as part of planar sp2-hybridized geometry transformed to distorted sp3-hybridized geometry, which loses its excellent electronic properties. As a result, reduction of GO is definitely necessary to recover its “lost” electrical conductivity for practical applications. In addition, the hydrophilic property of GO sheets allows metal oxide (MO) nanoparticles (NPs) anchoring on reduced graphene oxide (rGO) plane to fabricate MO/rGO composites with excellent electrochemical performance. However, the current preparation methods for the electrical conductive MO/rGO composites are very complicated which might have negative effects on the properties and hinder mass production. The objective of this project is to synthesize aluminium oxide (Al2O3)/rGO nanocomposites via oxygen annealing without using an Al2O3 precursor. This method establishes a very simple and efficient way to yield Al2O3 NPs on rGO plane by filtering GO dispersion through an Anodisc membrane filter with oxygen annealing, which is named oxygenally reduced graphene oxide (OrGO). The characterizations reveal that the Al2O3 NPs are formed exclusively on the edges of defective regions with uniform particle size less than 10 nm. As for the electronic properties, OrGO has a higher electrical conductivity at 7250 S m−1 with a narrower range of the electrical conductivity mostly between 6500 and 7250 S m−1, which can be due to the increase of the sp2/sp3 carbon ratio caused by the formation of Al2O3 NPs at the edges of defective regions in OrGO plane. Moreover, the formation of Al2O3 NPs maintains OrGO sheets with good hydrophilic property with a contact angle around 71.5°. The electrochemical performance of OrGO paper fabricated as electrode materials for lithium-ion batteries (LIBs) is also investigated. OrGO electrodes exhibit a high specific charge and discharge capacity at 1328 and 1364 mAh g−1. The cyclic voltammograms (CV) performance reveal that the insertion of Li+ ions begins at a very low potential around 0 V vs. Li+/Li while the extraction process begins in the range of 0.2–0.3 V. In addition, the OrGO electrode has excellent rate capability and cycling performance. The average coulombic efficiency (CE) was measured at 99.608% for 30 cycles, indicating a superior reversibility of the Li+ ion insertion/extraction process.
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Jasim, Dhifaf. "Graphene oxide derivatives for biomedical applications." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/graphene-oxide-derivatives-for-biomedical-applications(83c552dc-50f6-4771-95b4-d1aace0db493).html.
Повний текст джерелаАнотація:
Graphene-based materials (GBM) have recently generated great interest due to their unique two-dimensional (2D) carbon geometry, which confers exceptional physicochemical properties that hold great promise in many fields, including biomedicine. An understanding of how these novel 2D materials interact with the biological milieu is therefore fundamental for their development and use. Graphene oxide (GO) has been proven more biologically friendly than the highly hydrophobic pristine graphene. Therefore, the main aim of this study was to prepare well-characterised GO derivatives and test the hypothesis of their possible use for biomedical applications. GO was prepared reproducibly by a modified Hummers' method and further functionalised by using a radio-metal chelating agent, namely 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) to form GO-DOTA. The constructs were extensively studied using structural, optical and surface characterisation techniques. GO prepared from different forms of graphite demonstrated differences mainly in structure and production yields. However, all GO constructs were found biocompatible, with the mammalian cell cultures tested; furthermore, the biocompatibility of GO prepared as papers was retained when they were used as substrates for cell growth. Radiolabelling of GO-DOTA was further carried out to yield highly stable radio-labelled constructs, both in vitro and in vivo. These constructs were used for in vivo whole-body imaging and biodistribution studies in mice after intravenous administration. Extensive urinary excretion and accumulation mainly in the reticuloendothelial system (RES), including the spleen, liver and lungs, was the main fate of all the GO derivatives used in this thesis. The physicochemical characteristics were determined to play a central role for their preferential fate and accumulation. While the thicker sheets tended to accumulate mainly in the RES, the thinner ones were mostly excreted via the kidneys. Finally, it was crucial to perform safety investigations involving the structure and function of organs at high risk of injury (mainly the kidney and spleen). Our results revealed that no severe structural damage or histopathologic or functional abnormality of these vital organs. However, some preliminary inflammatory responses were detected that require further investigation. In summary, this study helped gain a better understanding of how thin 2D materials interact with biological barriers and the results indicate that these materials could be potential candidates for biological applications. Nevertheless, further investigations are necessary to confirm our findings.
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Li, Wei. "Composite polymer/graphite/oxide electrode systems for supercapacitors." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439309266.
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Andersson, Fredrik. "Graphene and graphene oxide as new lubricants in industrial applications." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-264853.
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This master thesis report evaluatesthe lubricating effect of graphene (G)and graphene oxide (GO). Thesematerials have been added, in particlecondition, in Ag-based slidingcontacts and lubricating greases. Thework focuses on the tribologicalevaluation of these materials,especially friction, wear and contactresistance analyses. The friction andwear behaviors of Ag-based contactscontaining of a wide concentrationrange of graphene and graphene oxideare tested against pure silver using atest load of 2 and 10 N at a constantspeed of 5 cm/s. It was revealed thatsmall amounts of G and GO are able tosignificantly reduce the frictioncoefficient and wear rate. Contactresistance measurements revealed thatresults similar to pure Ag can beachieved with G content up to 10vol%.Possible mechanisms, which maycontribute to this tribologicalbehavior are the Ag-C interactions andthe lubricating nature of graphene.Friction tests with G and GOcontaining lubricating greases showinconsistent results, and both greasesand corresponding test methods forevaluation require furtheroptimization. The overall, promising,tribological behavior of G and GOholds for the implementation invarious industrial applications. Thereis no doubt that these kinds ofmaterials can play an important rolein ABBs future work. This masterthesis report shows yet anotherapplication area for theseextraordinary materials.
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Sanga, Nelia Abraham. "Determination of heavy metals at the electrochemically reduced graphene oxide mercury film electrode (ERGO-HgF-PGE) using adsorptive stripping voltammetry." University of Western Cape, 2020. http://hdl.handle.net/11394/7718.
Повний текст джерелаАнотація:
>Magister Scientiae - MScThis work reports the use of a pencil graphite electrode (PGE) as inexpensive and sensitive electrochemical sensing platform fabricated by using electrochemically reduced graphene oxide (ERGO) in conjunction with an in-situ plated thin mercury film. For the first time the ERGOHgF-PGE sensor is proposed for simultaneous detection of cadmium (Cd2+), copper (Cu2+), lead (Pb2+) and zinc (Zn2+) using N-Nitroso-N-phenylhydroxylamine (cupferron) as complexing agent by square-wave adsorptive cathodic stripping voltammetry (SW-AdCSV). The technique is based on the adsorption of cupferron- metal ion complexes onto the surface of the ERGO-HgFPGE at 0.1 V for 60 s carried out in 0.1 M acetate buffer solution (pH 4.6). The synthesized graphene oxide (GO) and graphene nanosheets (GNs) were characterized using different analytical techniques such as FT-IR which confirms the presence of oxygen moieties embedded in the graphitic structure and further demonstrated by UV-Vis, validating the synthesis of GO
2023
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Gao, Pengcheng. "Matériaux carbonés nanostructurés pour supercapacités électrochimiques." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20028/document.
Повний текст джерелаАнотація:
Différents matériaux carbonés nanostructurés ont été synthétisés et mis en oeuvre comme matériaux supercapacitifs à double couche électrochimique (EDLC) ou comme substrats de matériaux pseudocapacitifs avec pour objectif d'augmenter leur densité de puissance. Nous avons ainsi développé une méthode de synthèse simple et originale de carbures de silicium (SiC) qui procède par une réduction topotactique d'un composite silice/carbon par le magnésium. Du fait de la température de synthèse inférieure à 800°C, SiC résultant conserve la morphologie et/ou la structure poreuse du précurseur composite. Par cette approche, nous pouvons moduler la structure poreuse ordonnée de SiC à façon, développer des porosités hiérarchiques méso/macro, préparer des feuillets ou des fibres de SiC. Les différentes formes de SiC ont été converties par chloration en autant de carbones, opération introduisant une microporosité supplémentaire. En électrolyte organique, ces carbones à porosité hierarchique combinent à la fois des capacités importantes issues de la microporosité mais également des performances inégalées en terme de puissance du fait de la méso ou macro-porosité associée. Dans une approche différente, des feuillet de graphène ont été décorés par voie sol-gel non-hydrolytique (micro-onde en milieu alcool benzilique) par des nanoparticules de FeOx. Le composite FeOx/graphene résultant combine simultanément les comportements EDLC et pseudocapacitif du graphène et de FeOx. Du fait de sa structure particulière, le composite FeOx/graphene conserve les performances en puissance du graphène auxquelles s'ajoutent celles d'énergie de FeOx. Nous avons également décoré des nanofibres de carbone avec des carbones mésoporeux. Après dépôt de MnO2 birnessite, les composites gagnent à la fois en capacité et en puissance en particulier avec des carbones présentant des pores supérieurs à 10nmVarious nanostructured carbon materials were synthesized and further served as active materials of electrical double layer capacitor or substrates of pseudocapacitive materials in order to improve power capability of corresponding supercapacitor. On the one hand, a simple synthesis of porous silicon carbides (SiCs) was achieved by performing a topotactic thermal reduction by magnesium (Mg) of a silica/ carbon composite. Thanks to the low synthetic temperature (below 800 ºC), the SiCs well preserved the pristine skeletons of their silica/carbon precursors. Successively, the SiCs with diverse porous structures from their silica/carbon precursor emerged, e.g. ordered tunable mesoporous SiCs, 3D-hierarchical meso and macroporous SiC, SiC nanosheet and SiC nanofiber. Furthermore, the porous SiCs derived from magnesio-thermal reduction were reduced to hierarchical carbons with newborn narrow distributed microporosity by chlorination. In an organic electrolyte, the hierarchical carbon combines the high specific capacitance from narrow distributed microporosity and the outstanding rate capability from ordered-arranged meso or macroporosity that make it promising for high power and energy density capacitor. On the other hand, a “benzyl alcohol route” has been used to decorate RGO nanosheets with FeOx nanoparticles. The resulting FeOx/ RGO composite, due to their hybrid nanostructure, combine both EDLC capacitive and pseudocapacitive bahaviors of RGO and FeOx, respectively. Thanks to the laminated RGO and nano FeOx particles film, the resulting composite gains the same power capability as RGO and a higher energy density than raw FeOx. Furthermore, mesoporous carbon was introduced to adorn the CNF surface through self-assemble of resol, carbon nanofiber(CNF) and Pluronic@127. After further coating with birnessite-MnO2, the composite electrode gains extra capacitance and power improvement in presence of superficially coating mesoporous carbon with pore size larger than 10nm
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Chau, Ngoc Do Quyen. "Can graphene oxide be a suitable platform for the complexation with nucleix acids?" Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF059.
Повний текст джерелаАнотація:
L'oxyde de graphène (GO) a attiré un intérêt croissant comme vecteur potentiel pour la délivrance de gènes, en particulier pour l’inhibition de gènes spécifiques. Le but principal de ce travail est le développement de nouvelles plateformes complexant de petits ARN interférents (siRNA) et la rationalisation des interactions supramoléculaires entre la surface du GO et l'ARN double brin. L'étude s'est concentrée d'abord sur la synthèse de GO avec divers groupes oxygénés, puis sur la fonctionnalisation covalente du GO avec des amines et des polymères. De plus, j'ai étudié les facteurs qui pourraient affecter la structure double hélice du siRNA. Enfin, la question que je me suis posé: « l’oxyde de graphène peut-il devenir une plateforme appropriée pour la complexation d’acides nucléiques ?» a été résolue à l’aide d’expériences biologiques prouvant la capacité du GO à délivrer du siRNA dans les cellulesGraphene oxide (GO) has attracted increasing interest as a prominent potential vector in gene delivery and in particular in gene silencing. The main goal of this work is to develop novel platforms to complex small interfering RNA (siRNA) molecules and to rationalize the supramolecular interactions between GO surface and the double strand RNA. The study focused first on the synthesis of GO with various oxygenated groups, subsequently chemically covalently modified with amines and polymers. Moreover, I investigated on the factors that could affect the double helix siRNA structure. Finally, the question of the thesis, « Can graphene oxide be a suitable platform for complexation of nucleic acids? » could be answered from the biological tests proving the ability of graphene derivatives as a carrier of siRNA into the cells
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Pacltová, Klára. "Ověřování vlastností betonů s nanočásticemi." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392361.
Повний текст джерелаАнотація:
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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Negreti, Maria Anita de Paula. "Obtenção e caracterização de compósitos poliméricos com óxido de grafeno reduzido." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-13032017-115009/.
Повний текст джерелаАнотація:
O grafeno, uma das formas alotrópicas do carbono, tem ganho grande valorização no meio científico e industrial devido às suas propriedades excepcionais. Por apresentar condutividade elétrica correspondente a do cobre e condutividade térmica, dureza e resistência superiores a todos os outros materiais existentes, faz-se necessário à busca por melhores, mais eficientes e produtivos métodos de obtenção do mesmo. Um dos métodos mais utilizados atualmente, conhecido como método de Hummers, consiste na oxidação da grafita por tratamentos ácidos e posterior redução (química ou térmica). No entanto, o rendimento do processo, geralmente, não gera quantidade de material suficiente para preparo de compósitos poliméricos utilizando equipamentos tradicionais de mistura, como extrusoras. Os compósitos poliméricos com grafeno apresentam aumento na estabilidade térmica e dimensional de peças injetadas, quando comparado à mesma peça sem carga, podendo ser usado como retardante de chama e também, por garantir maior condutividade elétrica ao polímero, pode ser usado em touch screens e células solares flexíveis. Frente a estas possibilidades, faz-se necessário aperfeiçoar o método de Hummers, tornando-o mais eficaz e produtivo. Alguns parâmetros da cinética química da reação do óxido de grafite (GO), os métodos de remoção dos ácidos residuais do processo, as técnicas de redução dos grupos oxigenados e o método de obtenção do material seco para posterior incorporação no polímero foram avaliados neste trabalho. Três métodos de oxidação da grafita foram estudados e os materiais obtidos foram comparados ao GO comercial, e dois métodos de redução (química com NaBH4 e térmica à várias temperaturas e taxas de aquecimento) do GO foram testados. Os GOs e os óxidos de grafeno reduzidos (GORs) foram caracterizados com o auxílio das técnicas de espectroscopia Raman, espectroscopia vibracional de absorção no infravermelho (FTIR), análise termogravimétrica (TGA), microscopia eletrônica de varredura (MEV), espectrometria de raios X por energia dispersiva (EDS) e difração de raios-X (DRX). Os resultados mostraram que a cinética da reação de GO não é linear, pois foram obtidos óxidos com características diferentes, utilizando-se a mesma proporção de reagentes pelos métodos A e C. A filtração ou a diálise, utilizadas para remover os resíduos ácidos do tratamento, e a estufa ou a liofilização, utilizadas para obter os materiais secos, não interferiram nas propriedades finais dos GOs e dos GORs. Por fim, a redução química e o choque térmico a 700 °C se mostraram os métodos mais adequados para obter grafeno quimicamente modificado com boas propriedades e maior rendimento. Os compósitos obtidos através de um misturador interno foram caracterizados com ensaios mecânicos (tração e impacto), microscopia eletrônica de varredura (MEV), microscopia eletrônica de transmissão (MET) e calorimetria exploratória diferencial (DSC). Os resultados obtidos indicaram a má dispersão das cargas no polímero, o que pode ser confirmado pela presença de aglomerados nas análises morfológicas e pelas propriedades mecânicas inferiores dos compósitos.The graphene, one of the carbon allotropes, has received a great valorization in the scientific and industrial areas due its exceptional properties. Its electrical conductivity corresponds to copper ones and its thermal conductivity, hardness and strength are superior to known existent material properties. For this reason, it is necessary to search for a more efficient and productive method of obtaining. One of the most used methods nowadays is the Hummers method, it is based on graphite oxidation via acid treatment and also on chemical and thermal reduction. However, the yield of the process generally does not generate sufficient amount of material for preparing polymer composites using traditional mixing equipment such as extruders. Polymeric composites graphene have increased thermal and dimensional stability of molded parts compared to the same part without load, can be used as a flame retardant and also to ensure higher electrical conductivity to the polymer, can be used in touch screens and flexible solar cells. Faced to these possibilities, it is necessary to search for improvements to Hummers method, making it more effective and productive. Evaluating the chemical kinetic from the reaction of graphite oxide (GO), the removal manners from the residual acids from the process, the reduction technician from the oxygenated functional groups and the obtention method of the dry material to posterior incorporation in to the polymer, were evaluated in this work. Three oxidation methods have been performed and compared to GO commercial, and three reduction methods (chemical with NaBH4 and thermal to 550 °C and 1000 °C) have been tested. The GOs and the graphene oxide reduced (GORs) were characterized by Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopic (SEM) and Energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The results showed that the reaction kinetic from the GO is not linear, because it has been obtained oxides with different characteristics, using the same reagents proportion in two methods (A and C). The filtration or the dialysis, used to remove the acids residues from the treatment, and the drying oven or the freeze drying, used to obtain the dry material, didn\'t interfere in the final properties of the GOs and GORs. Finally, the chemical reduction and the thermal shock at 700 ° C proved the most suitable methods for chemically modified graphene with good properties and increased yield. The composites obtained through an internal mixer were characterized with mechanical tests (tensile and impact), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). Results indicated poor dispersion of the fillers in the polymer, which can be confirmed by the presence of agglomerates in the morphological analysis and the inferior mechanical properties of the composites.
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Valim, Fernanda Cabrera Flores. "Comportamento reológico de compósitos reforçados com óxido de grafite em matriz de poli(metacrilato de metila)." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-12072016-114838/.
Повний текст джерелаАнотація:
Neste trabalho, foram obtidos compósitos poliméricos de Óxido de Grafite (GO) incorporado em Poli(metaclilato de metila) (PMMA). A obtenção do Óxido de Grafite foi realizada por dois diferentes métodos: método de Hummers modificado e método de Staudenmaier. Em seguida, foi ainda adicionada uma etapa secundária de tratamento térmico à 1000 ºC nos GOs obtidos a fim de expandir as lamelas de grafite e remover os grupos funcionais aderidos durante o ataque ácido do grafite. As cargas obtidas foram caracterizadas com o auxílio das técnicas de Difração de Raios-X (DRX), Espectroscopia Raman, Espectroscopia Vibracional no Infravermelho (FTIR), Análise Termogravimétrica (TGA), Microscopia Eletrônica de Varredura (MEV), Microscopia Eletrônica de Transmissão (MET) e Microscopia de Força Atômica (AFM), constatando a formação do Óxido de Grafite por ambos os métodos, e ainda a expansão das folhas após o tratamento térmico. O estudo comparativo dos compósitos de matriz polimérica com 1, 3 e 5 % de concentração de GO antes do tratamento térmico e 1 e 3 % após o tratamento térmico foi realizado com o objetivo de entender a contribuição nas propriedades reológicas do polímero com a adição da carga de GO. Os compósitos poliméricos foram obtidos através de um misturador interno, variando-se o método de adição da carga na matriz polimérica via solvente ou via moinho - para estudar a melhor dispersão da carga na matriz. Os compósitos PMMA/GO foram caracterizados por Cromatografia de Permeação em Gel (GPC), Análise Termogravimétrica (TGA), Calorimetria Exploratória Diferencial (DSC), Microscopia Eletrônica de Varredura (MEV), Microscopia Eletrônica de Transmissão (MET); e por ensaios reológicos de Varredura de Deformação, Varredura de Tempo, e Cisalhamento Oscilatório de Pequenas Amplitudes (COPA). Os resultados reológicos apresentaram um aumento da viscosidade complexa tanto na Varredura de Tempo, quanto no COPA. De acordo com a metodologia adotada, ainda não foi possível verificar o aumento crescente da viscosidade complexa a baixas frequências. Este aumento de viscosidade indicaria que o Óxido de Grafite formou uma rede tridimensional, cuja percolação impede que as cadeias poliméricas relaxem completamente.In this study, composites of graphite oxide (GO) in poly(methyl methacrylate) (PMMA) were obtained. Obtaining of graphite oxide was performed by two potential methods by literature: modified Hummers method and Staudenmaier method; Then, a secondary GOs obtained heat treatment step - at 1000° C - was added in order to expand the graphite flakes and remove functional groups attached during the acid attack of graphite. The reinforcement obtained by both methods were characterized by X-Ray Diffraction (XRD), Raman Spectroscopy, Infra Red Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM), confirming the formation of Graphite Oxide by both methods, and also the expansion of the leaves after the heat treatment. Then, a comparative study of the polymer matrix composites with 1, 3 and 5 % concentration of oxides graphite before the heat treatment and 1 and 3 % after the heat treatment was performed in order to understand the contribution to the rheological properties of the polymer with the addition of GO reinforcement. The composites were obtained by internal mixer, varying the load adding method in the polymeric matrix - via mill and via solvent - to study the best dispersion of GO in the matrix. The samples were characterized by Gel Permeation Ghromatography (GPC), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM); and rheological measurements of Deformation Scan, Time Sweep, and Small Amplitude Oscillatory Shear (SAOS). The rheological results showed an increase in complex viscosity at both Time Sweep, as in SAOS. However, it was not possible to verify the increase of complex viscosity at low frequencies, that would indicate that graphite oxide form a three-dimensional arrangement, which prevents the percolation of the polymer chains, letting them to relax completely.
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Alrammouz, Rouba. "Conception et réalisation d’un système de détection de gaz à faible coût sur substrat flexible." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS134.
Повний текст джерелаАнотація:
Les préoccupations actuelles de protection de l’environnement et de la santé publique se focalisent sur la qualité de l’air dans l’industrie, les villes et foyers domestiques. De nos jours, les capteurs de gaz sur papier présentent un intérêt croissant au vu de leur faible coût, leur biodégradabilité, leur flexibilité, et leurs applications dans les textiles, les pansements et les emballages intelligents.L’oxyde de graphène (GO) est un dérivé du graphène qui présente des propriétés électriques, mécaniques et thermiques exceptionnelles. Ce matériau est très prometteur pour le développement de capteurs de gaz peu chers et fonctionnant à température ambiante.Dans ce contexte, cette thèse a pour objectif d’intégrer une couche sensible d’oxyde de graphène dans un papier poreux pour la détection de gaz. La première partie de ce travail est consacrée à la mise au point et à l’optimisation d’un processus de fabrication et de fonctionnalisation de capteurs capacitifs poreux sur papier. Un nouveau processus de réduction locale d’oxyde de graphène sur papier en électrodes est également introduit. Il s’agit de la thermocompression, économique et compatible avec la fabrication grande échelle.La seconde partie du travail porte sur l’étude des propriétés de détection d’humidité et d’ammoniac des capteurs. L’oxyde de graphène sur papier, présente une sensibilité élevée à l’ammoniac, l’humidité étant un gaz interférent. La réduction locale du GO en électrodes, et sa fonctionnalisation par de l’oxyde de zinc augmentent la sensibilité et la sélectivité des capteurs à l’humidité. Les capteurs fabriqués sont répétables, stables, reproductibles et flexiblesCurrent concerns for environmental protection and public health focus on air quality in industries, cities and households. Nowadays, paper-based gas sensors are of increasing interest due to their low cost, biodegradability, flexibility and applications in e-textiles, e-dressings and e-packaging.Graphene oxide is a derivative of graphene with exceptional electrical, mechanical and thermal properties. Graphène oxide is a promising material for the development of low-cost room temperature gas sensors.In this context, this thesis aims to integrate a graphene oxide sensing layer inside a porous paper substrate for humidity and ammonia detection. The first part of this work focuses on the fabrication, functionalization and optimization of capacitive porous gas sensors on paper. A new local reduction process of graphene oxide into electrodes is introduced. The process is hot-plating, a low cost technique compatible with large scale productionThe second part of this work studies the humidity and ammonia sensing capabilities of the sensors. Graphene oxide on paper exhibits a high sensitivity towards ammonia, with humidity as an interfering gas. The local reduction of graphène oxide into electrodes, and its functionalization with zinc oxide increased the sensitivity and selectivity of the device towards humidity. The fabricated sensors exhibit a good repeatability, reproducibility and flexibility
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Nesser, Hussein. "Fabrication et caractérisation des MEMS composite pour la récupération d'énergie mécanique." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0269/document.
Повний текст джерелаАнотація:
Les récents progrès dans le domaine des MEMS organiques suscitent un intérêt croissant dans la substitution de micropoutres inorganiques par des micropoutres organiques pour diverses applications. N’ayant été étudiée qu’en mode statique, la réponse électrostrictive des MEMS organiques est présentée pour la première fois en mode dynamique. L’une des originalités de ce travail est de fabriquer un micro-récupérateur d’énergie mécanique avec une approche « tout-organique ». Dans cette thèse, des matériaux nanocomposites à base d’oxyde de graphène réduit (rGO) dispersé dans du poly-dimethyl siloxane (PDMS), sont utilisés pour la récupération de l'énergie mécanique vibratoire avec une transduction électrostrictive. Le dispositif génère une densité de puissance électrique de 8,15 W/cm3 pour une accélération de 1 g au premier mode de résonance (≈ 17 Hz)Recent advances in the field of organic MEMS have generated interest in the substitution of inorganic microbeams by organic ones for various applications. Until now, the use of electrostrictive materials is limited to the MEMS operating mostly in static mode. The electrostrictive response of organic MEMS is presented here for the first time in dynamic mode. One of the originality of this work is to produce a micro-mechanical energy harvester fabricated in an all-organic approach. In this thesis, strain sensitive nanocomposite materials based on reduced graphene oxide (rGO) dispersed in polydimethylsiloxane (PDMS) are used for mechanical vibratory energy harvesting with an electrostrictive transducer. With an acceleration of 1 g of the microcantilever base, actuation at the first resonant mode (≈ 17 Hz) generates an electrical power density of 8.15 μW/cm3
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Jiang, San-Ping. "A study of teflon-bonded cobalt oxide/graphite electrodes." Thesis, City University London, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306058.
Повний текст джерела
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Shulga, Y. M., S. A. Baskakov, E. I. Knerelman, G. I. Davidova, E. R. Badamshina, S. Y. Shulga, E. A. Skrileva, A. L. Agapov, D. N. Voylov, and A. P. Sokolov. "Carbon Nanomaterial Produced by Microwave Exfoliation of Graphite Oxide." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35118.
Повний текст джерелаАнотація:
Carbon-based graphene-like material was obtained through microwave stimulated exfoliation of graph-ite oxide (GO). Properties of this material were investigated by multiple techniques including element analysis, X-ray photoelectron spectroscopy (XPS), mass-spectroscopy, infrared (IR) and Raman spectrosco-py, scanning electron microscopy (SEM) and broadband dielectric spectroscopy. Specific surface area and volume of microwave exfoliated graphite oxide (MEGO) reached 600 m2/g and 6 cm3/g, respectively. It is shown that during such explosive reduction process the sample emits CO2, CO and H2O and, in some cases, SO2 gases. The resulting reduced material exhibits IR spectra similar to that of graphite and a dc-conductivity of 0.12 S/cm. It is also shown that prolonged storage in ambient conditions leads to elevated oxygen content and decrease of specific surface area of the samples.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35118
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Dave, Shreya H. "Assessing graphene oxide for water desalination applications." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107077.
Повний текст джерелаАнотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 121-133).
Water desalination plays a critical role in augmenting the fresh water supplies for water scarce regions. However, despite considerable improvements in system efficiencies, it still remains six to ten times more expensive than treating freshwater for drinking. As a result, the construction and operation of a desalination plant places considerable economic burden on the regions that require such an investment. As more and more regions experience water stress due to climate change, increased industrial consumption, and population growth, materials engineering will play a role in improving the economics. The membranes used in today's reverse osmosis plants are made from polymers that are fragile, limited in the flux, and typically operate at 70% of their rated performance due to biofouling. Following the exciting proposition of using graphene as a size-exclusion based desalination membrane, there has been a great deal of revived interest in the development of new membrane materials that overcome these challenges. Graphene oxide, made from the chemical exfoliation of graphite, has served as a promising candidate for membrane applications because it is cheaper than graphene to produce and yet demonstrates similar benefits of resilience and increased permeability. In this work, we take a critical look at three aspects of graphene oxide as it applies to the development of water desalination membranes. First, we present an atomic study of the structure of graphene oxide (GO) that is produced in bulk quantities. In contrast to previous work, which has examined particularly defect free GO, we find that GO develops a nanocrystalline structure in support of a Dynamic Structural Model in its hexagonal carbon lattice. Second, we detail the development of a new cross-linker that enables the fabrication of stable GO films with sub-nanometer interlayer spacing and demonstrated nanofiltration performance. The process of cross-linking and membrane fabrication is entirely solution based and therefore promising for scale up. Finally, we evaluate the techno-economic feasibility of a GO as a water desalination material with a comparison between estimated production cost and savings in terms of the levelized cost of water. We quantitatively assess GO membranes as a scalable technology and identify other separation areas that could be served by robust membrane materials. With these three diverse analyses, I aim to provide a research-based perspective as to the material system, technological hurdles, and the economic potential of graphene oxide membranes.
by Shreya H. Dave.
Ph. D.
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Thomas, Helen R. "The structure and reactivity of graphene oxide." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/74090/.
Повний текст джерелаАнотація:
Graphene oxide (GO) can provide a cost-effective route to a graphene-like material on an industrial scale, but produces an imperfect product. In order to improve the quality of the resultant graphene, unanswered questions regarding the structure and chemical reactivity of GO need to be addressed. In this thesis, chapters 1 and 2 serve to introduce the field of graphene and graphene oxide research, as well as standard characterisation techniques. Chapter 3 is concerned with investigating the validity and general applicability of a recently proposed two-component model of GO – the formation of the two components was shown to be largely independent of the oxidation protocol used in the synthesis, and additional characterisation data was presented for both base-washed graphene oxide (bwGO) and oxidation debris (OD). The removal of the OD cleans the GO, revealing its true mono-layer nature and in the process increases the C:O ratio, i.e. a deoxygenation. By contrast, treating GO with hydrazine was found to both remove the debris and reduce (cleaning and deoxygenation) the graphene-like sheets. In chapter 4, different nucleophiles were used to explore bwGO functionalisation via epoxy ring-opening reactions. Treatment of bwGO with potassium thioacetate, followed by an aqueous work-up, was shown to yield a new thiol functionalised material (GO-SH). As far as is known, this was the first reported example of using a sulfur nucleophile to ring open epoxy groups on GO. The incorporation of malononitrile groups, and the direct grafting of polymer chains to the graphene-like sheets was also demonstrated. The thiol groups on GO-SH are amendable to further chemistry and in chapter 5 this reactivity is exploited with alkylation, thiol-ene click and sultone ring-opening reactions. Au(I) and Pd(II) metallo-organic complexes were also prepared, and gold deposition experiments were carried out, demonstrating that GO-SH has a strong affinity for AuNPs. These CMGs have varying solubility and improved thermal stability. Chapter 6 concludes the work covered in this thesis, and full experimental details can be found in chapter 7.
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Tu, Yudi. "Photo Processing and Microfabrication of Graphene Oxide." Kyoto University, 2018. http://hdl.handle.net/2433/232039.
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