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Nair, Rahul Raveendran. "Atomic structure and properties of graphene and novel graphene derivatives." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527419.
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Eckmann, Axel. "Raman spectroscopy of graphene, its derivatives and graphene-based heterostructures." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/raman-spectroscopy-of-graphene-its-derivatives-and-graphenebased-heterostructures(fbb9d645-4fb3-4a75-b5c9-9a8483d6e9ac).html.
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In less than a decade of research, graphene has earned a long list of superlatives to its name and is expected to have applications in various fields such as electronics, photonics, optoelectronics, materials, biology and chemistry. Graphene has also attracted a lot of attention because its properties can be engineered either via intrinsic changes or by modification of its environment. Raman spectroscopy has become an ideal characterization method to obtain qualitative and quantitative information on these changes. This thesis investigates the possibility to change, supplement and monitor the electonic and optical properties as well as the chemical reactivity of graphene. It is achieved by i) substrate effect, ii) introduction of defects in the structure of graphene and iii) the combination of graphene with other two- dimensional crystals such as hexagonal boron nitride (h-BN) and transition metal dichacolgenides. In particular, the experimental work presented here describes: I - The influence of the type of substrate on the Raman intensity of graphene. This work leads to the calculation of the Raman scattering efficiency of graphene after CaF2 is found to be a suitable substrate for this kind of study in contrast to Si/SiOx that strongly modulates the Raman intensities. The G peak scattering efficiency is found to be about 200 x 10-5 m-1 Sr-1 at 2.4 eV while that of the 2D peak is one order of magnitude higher, confirming the resonant nature of the 2D peak Raman scattering process. II - An attractive method to produce large (up to several hundreds of microns across) and high quality graphene by anodic bonding. This cheap, fast and solvent-free method also allows introduction of vacancy like defects in the samples in a relatively controllable way. III - The Raman signatures of several types of defect such as sp3 sites, vacancies and substitutional atoms. For low defect concentration (stage 1) the intensitiy ratio I(D)/I(D') is constant and is 13 for sp3 sites, 9 for substitutional atoms and 7 for vacancies. This signature is explained using the local activation model recently proposed to model the amorphization trajectory of graphene with containing vacancy-like defects. IV - Controlled modification of graphene through mild oxygen plasma. The influence of sp3 sites on monolayer and bilayer graphene's electrical properties are discussed. In the case of bilayer under controlled conditions, it is possible to modify only the top layer. This may lead to decoupling between the two layers, which could explain the good mobility measured for this system. The possiblity to use such system as a sensor is discussed. V - The characteristic Raman signature of aligned graphene/h-BN superlattices. The Raman spectrum shows strong changes in perfectly aligned superlattices, which could be attributed to the reconstruction of the Dirac spectrum. VI - A prototype photovoltaic cell made of a graphene and tungsten disulphide (WS2) heterostructure with an external quantum efficiency of about 30%. The beneficial combination of an excellent absorption in WS2 atomically thin films due to the presence of van Hove singularities and graphene used as a transparent, flexible and conductive electrode is demonstrated.
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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.
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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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Treossi, Emanuele <1974>. "Chemical Production and Microelectronic Applications of Graphene and Nano-Graphene Derivatives." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4641/1/treossi_emanuele_tesi.pdf.
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Graphene and graphenic derivatives have rapidly emerged as an extremely promising system for electronic, optical, thermal, and electromechanical applications. Several approaches have been developed to produce these materials (i.e. scotch tape, CVD, chemical and solvent exfoliation). In this work we report a chemical approach to produce graphene by reducing graphene oxide (GO) via thermal or electrical methods. A morphological and electrical characterization of these systems has been performed using different techniques such as SPM, SEM, TEM, Raman and XPS.
Moreover, we studied the interaction between graphene derivates and organic molecules focusing on the following aspects:
- improvement of optical contrast of graphene on different substrates for rapid monolayer identification1
- supramolecular interaction with organic molecules (i.e. thiophene, pyrene etc.)4
- covalent functionalization with optically active molecules2
- preparation and characterization of organic/graphene Field Effect Transistors3-5
Graphene chemistry can potentially allow seamless integration of graphene technology in organic electronics devices to improve device performance and develop new applications for graphene-based materials.
[1] E. Treossi, M. Melucci, A. Liscio, M. Gazzano, P. Samorì, and V. Palermo, J. Am. Chem. Soc., 2009, 131, 15576. [2] M. Melucci, E. Treossi, L. Ortolani, G. Giambastiani, V. Morandi, P. Klar, C. Casiraghi, P. Samorì, and V. Palermo, J. Mater. Chem., 2010, 20, 9052. [3] J.M. Mativetsky, E. Treossi, E. Orgiu, M. Melucci, G.P. Veronese, P. Samorì, and V. Palermo, J. Am. Chem. Soc., 2010, 132, 14130. [4] A. Liscio, G.P. Veronese, E. Treossi, F. Suriano, F. Rossella, V. Bellani, R. Rizzoli, P. Samorì and V. Palermo, J. Mater. Chem., 2011, 21, 2924.
[5] J.M. Mativetsky, A. Liscio, E. Treossi, E. Orgiu, A. Zanelli, P. Samorì , V. Palermo, J. Am. Chem. Soc., 2011, 133, 14320
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Treossi, Emanuele <1974>. "Chemical Production and Microelectronic Applications of Graphene and Nano-Graphene Derivatives." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4641/.
Full textAbstract:
Graphene and graphenic derivatives have rapidly emerged as an extremely promising system for electronic, optical, thermal, and electromechanical applications. Several approaches have been developed to produce these materials (i.e. scotch tape, CVD, chemical and solvent exfoliation). In this work we report a chemical approach to produce graphene by reducing graphene oxide (GO) via thermal or electrical methods. A morphological and electrical characterization of these systems has been performed using different techniques such as SPM, SEM, TEM, Raman and XPS.
Moreover, we studied the interaction between graphene derivates and organic molecules focusing on the following aspects:
- improvement of optical contrast of graphene on different substrates for rapid monolayer identification1
- supramolecular interaction with organic molecules (i.e. thiophene, pyrene etc.)4
- covalent functionalization with optically active molecules2
- preparation and characterization of organic/graphene Field Effect Transistors3-5
Graphene chemistry can potentially allow seamless integration of graphene technology in organic electronics devices to improve device performance and develop new applications for graphene-based materials.
[1] E. Treossi, M. Melucci, A. Liscio, M. Gazzano, P. Samorì, and V. Palermo, J. Am. Chem. Soc., 2009, 131, 15576. [2] M. Melucci, E. Treossi, L. Ortolani, G. Giambastiani, V. Morandi, P. Klar, C. Casiraghi, P. Samorì, and V. Palermo, J. Mater. Chem., 2010, 20, 9052. [3] J.M. Mativetsky, E. Treossi, E. Orgiu, M. Melucci, G.P. Veronese, P. Samorì, and V. Palermo, J. Am. Chem. Soc., 2010, 132, 14130. [4] A. Liscio, G.P. Veronese, E. Treossi, F. Suriano, F. Rossella, V. Bellani, R. Rizzoli, P. Samorì and V. Palermo, J. Mater. Chem., 2011, 21, 2924.
[5] J.M. Mativetsky, A. Liscio, E. Treossi, E. Orgiu, A. Zanelli, P. Samorì , V. Palermo, J. Am. Chem. Soc., 2011, 133, 14320
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MANGADLAO, JOEY DACULA. "Multifunctional Materials from Nanostructured Graphene and Derivatives." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1448279230.
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VAZQUEZ, SULLEIRO MANUEL. "COVALENT FUNCTIONALIZATION OF GRAPHENE DERIVATIVES FOR NOVEL CARBON INTERFACES." Doctoral thesis, Università degli Studi di Trieste, 2018. http://hdl.handle.net/11368/2919820.
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Graphene is an allotrope of carbon material with a unique set of properties. Since it discovery in 2004 the number of publications about this material grew really fast. In the first chapter of this work, a general introduction of these topics, an overview of this material and relevant characterization techniques is described.
Chemical functionalization of graphene is a topic of paramount importance, because it allows for the fine-tuning of material’s chemical and physical properties. An additional challenge in graphene functionalization is the surface modification in a controlled way, in order to create novel carbon interfaces to introduce functional biomolecules, like DNA or proteins, which are often used in biosensors and bioelectronics.
Chapter 2 discuss the exploration of conventional routes for the preparation and functionalization of graphene. With special emphasis in the underexplore aryne cycloadditions. Besides, the selection of a suitable graphene material for the setting of an electrochemical functionalization of graphene electrodes with future application as biosensor platforms. Moreover, the development of an early-stage essay biosensor of a modified graphene electrode for the electrochemical detection of oligonucleotides. By last, the study of a novel, fast and scalable non-conventional functionalization under microwave irradiation that can solve common problems of the conventional modifications of carbon materials.
The present results could open a range of possibilities for the scientific community, paving the way to new functionalization protocols with fast, efficient, large-scale and green procedures to obtain more user-friendly graphene materials and to create novel organic interfaces on diverse graphene derivatives for the manufacture of future biosensors and bioelectronic devices.
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Tsai, I.-Ling. "Magnetic properties of two-dimensional materials : graphene, its derivatives and molybdenum disulfide." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/magnetic-properties-of-twodimensional-materials-graphene-its-derivatives-and-molybdenum-disulfide(59dcba1b-332e-4a58-86f6-80ed56c7fdd1).html.
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Graphene, an atomically thin material consisting of a hexagonal, highly packed carbon lattice, is of great interests in its magnetic properties. These interests can be categorized in several fields: graphene-based magnetic materials and their applications, large diamagnetism of graphene, and the heterostructures of graphene and other two dimensional materials. In the first aspect, magnetic moments can be in theory introduced to graphene by minimizing its size or introducing structural defects, leading to a very light magnetic material. Furthermore, weak spin-orbital interaction, and long spin relaxation length make graphene promising for spintronics. The first part of this thesis addressed our experimental investigation in defect-induced magnetism of graphene. Non-interacted spins of graphene have been observed by intentionally introducing vacancies and adatoms through ion-irradiation and fluorination, respectively. The defect concentration or the magnetic moments introduced in this thesis cannot provide enough interaction for magnetic coupling. Furthermore, the spins induced by vacancies and adatoms can be controlled through shifting the Fermi energy of graphene using molecular doping, where the adatoms were alternatively introduced by annealing in the inert environment. The paramagnetic responses in graphene induced by vacancy-type defects can only be diverted to half of its maximum, while those induced by sp3 defects can be almost completely suppressed. This difference is supposed that vacancy-type defects induced two localized states (pie and sigma). Only the latter states, which is also the only states induced by sp3 defects, involves in the suppression of magnetic moments at the maximum doping achieved in this thesis. The observation through high resolution transmission electron microscope (HR-TEM) provides more information to the hypothesis of the previous magnetic findings. Reconstructed single vacancy is the majority of defects discovered in proton-irradiated graphene. This result verifies the defect-induced magnetic findings in our results, as well as the electronic properties of defected graphene in the literatures. On the other hand, the diamagnetic susceptibility of neutral graphene is suggested to be larger than that of graphite, and vanish rapidly as a delta-like function when graphene is doped. In our result, surprisingly, the diamagnetic susceptibility varies little when the Fermi level is less than 0.3 eV, in contrast with the theory. When the Fermi energy is higher than 0.3 eV, susceptibility then reduces significantly as the trend of graphite. The little variation in susceptibility near the Dirac point is probably attributed to the spatial confinement of graphene nanoflakes, which are the composition of graphene laminates. In the end of this thesis, we discuss the magnetic properties in one of the other two dimensional materials, molybdenum disulfide (MoS2). It is a potential material for graphene-based heterostructure applications. The magnetic moments in MoS2 are shown to be induced by either edges or vacancies, which are introduced by sonication or proton-irradiation, respectively, similar to the suggestions by theories. However, no significant ferromagnetic finding has been found in all of our cases.
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Hassan, Md Mahbub. "Synthesis of Graphene and its Derivatives for Electrochemical Energy Storage and Conversion Applications." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14069.
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A high yield aqueous phase exfoliation route for few layers graphene sheets (FLGs) was developed using expanded graphite as starting precursor. Afterward graphene derivatives such as activated graphene, graphene quantum dots, heteroatom doped graphene and graphene/polyaniline (PANI) nanocomposite were serially produced using this high quality FLGs as precursor materials. FLGs with high yield (90%) were first time synthesized by a very simple and quick (60 min) one step ultrasonication process. Incorporation of small portion (1 wt %) of this FLGs significantly enhanced the thermal and electrical properties of a polystyrene based composite. Activation by KOH of the FLGs produced activated few layers graphene sheets (aFLGs) with nanoporous morphology and 19 folds higher surface areas. The ultrasonic waves further caused easy ripping in the bridged porous structure of aFLGs resulting the production of reduced size graphene quantum dots (GQDs). This new type of dots named activated graphene quantum dots (aGQDs) was first time introduced in material world and compared to conventional GQDs, it exhibited enhanced BET surface area by a factor of about six, the photoluminescence intensity by about four and half times and electrochemical double layer-capacitance by a factor of about two. Moreover the heteroatoms, nitrogen (N) and Iodine (I) were simultaneously doped on the aFLGs resulting in NIG. This is a first demonstration for Iodine to be used as dual dopant with any nanocarbon materials and showed the direct 4e- reduction process and synergistic electrocatalytic activity than that of its singularly doped N and I counterpart in oxygen reduction reaction (ORR) application. A standalone flexible composite film was also synthesized by electrostatic interaction between PANI nanospheres and GO sheets. A new method for in-situ chemical reduction of GO in composite by hydroiodic acid (HI) produced the 3D open structure of graphene/PANI without altering their pre-built hierarchical network. The electro-capacitance of the film was enhanced by 60% through the synergistic combination of graphene and PANI nanostructures and about 81% capacity retention was achieved for the composite compared to 38% for PANI alone after subjecting the samples to 5000 cyclic operations.
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Wychowaniec, Jacek. "Designing nanostructured peptide hydrogels containing graphene oxide and its derivatives for tissue engineering and biomedical applications." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/designing-nanostructured-peptide-hydrogels-containing-graphene-oxide-and-its-derivatives-for-tissue-engineering-and-biomedical-applications(409e60a2-ed17-45bf-ab6c-b76ede937a67).html.
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Progress in biomedicine requires the design of functional biomaterials, in particular, 3-dimensional (3D) scaffolds. Shear thinning, β-sheet based peptide hydrogels have attracted wide interest due to their potential use in tissue engineering and biomedical applications as 3D functional scaffolds. The emergence of carbon nanomaterials has also opened the door for the construction of increasingly functional hybrid hydrogels built from nanofibres and graphene-based materials using non-covalent physical interactions. The relationship between peptide molecular structure and the formed hydrogel is important for understanding the material response to shear. In particular, the physicochemical properties of peptide based biomaterials will affect the feasibility of injecting them during medical procedures. In the first part of this work, four peptides: FEFKFEFK (F8), FKFEFKFK (FK), KFEFKFEFK (KF8) and KFEFKFEFKK (KF8K) (F - phenylalanine, E - glutamic acid, K - lysine) were designed and used at identical charge to explore the effect of lysine rich β-sheet self-assembling sequences on the shear thinning behaviour and final properties of bulk hydrogels. By varying the peptide sequence design and concentration of the peptide, the tendency of the nanofibres formed to aggregate and the balance of nanofibre junction strength versus fibre cohesive strength could be explored. This allowed the existing theory of the shear thinning behaviour of this class of materials to be extended. The relationship between molecular structures of nanofibres forming the 3D network and the nano-filler is critical to understand in order to design tuneable and functional materials. In the next part of the work, three rationally designed β-sheet peptides, which form hydrogels: VEVKVEVK (V8), FEFKFEFK (F8) and FEFEFKFE (FE) (V - valine) and five graphene-based materials: graphene oxide (GO), reduced graphene oxide (rGO), three graphene-polymer hybrid flakes: GO with polydiallyldimethylammonium chloride (GO/PDADMAC), rGO with PDADMAC (rGO/PDADMAC) and rGO with polyvinylpyrrolidone (rGO/PVP) were used to form a selection of hybrid hydrogels. Graphene derivatives of the lateral flake sizes of 16.8 ± 10.1 µm were used. Various interactions between the graphene flakes and the peptides were observed that affected the overall mechanical properties of the hydrogels. Electrostatic interactions and pie-pie stacking, when phenylalanine residues are present, were shown to play a key role in determining the dispersion of graphene materials in the peptide hydrogels and stiffness of the hybrid materials. In particular, FE with reduced graphene oxide (rGO) and FE with rGO covered with polydiallyldimethylammonium chloride (PDADMAC) thin film formed double network-like hybrid hydrogels due to strong formation of peptide nanofibrillar bridges between adjacent rGO flakes. This corresponded to the 3- and 4-fold increase in the storage modulus (Gꞌ) of these hydrogels in comparison to controls. FE hydrogels with homogeneus dispersions of graphene oxide (GO) and reduced graphene oxide (rGO) are further shown to be suitable for 3D culture of human mesenchymal stem cells (hMSCs) with no cytotoxicity. These results focus attention on the importance of understanding interactions between the nano-filler and the nanofibrillar network in forming hybrid hydrogels with tuneable mechanical and biological properties, and demonstrates the possibility of using these materials as 3D cell culture scaffolds for biomedical purposes. Furthermore, graphene oxide (GO) itself is currently used in a number of processes of technological relevance such as wet spinning, injection moulding or inkjet printing to form graphene fibres, composites and printed conductors. Typically, such processes utilise well-aligned layered GO liquid crystal (LC) structures in aqueous dispersions. Flow and confinement encountered during processing affects the alignment and stability of this phase. In the final part of this work, the alignment of GOLCs of two lateral flake sizes (42.1 ± 29.4 µm and 15.5 ± 7.5 µm) were probed under a wide range of rotational shear flow conditions that overlap with the manufacturing processes defined by angular speeds from 0.08 to 8 rad.s-1 (and corresponding maximum shear rates from 0.1 s-1 to 100 s-1), in real-time, using shear induced polarized light imaging and small angle X-ray scattering, both coupled with an in-situ rheometer (Rheo-SIPLI and Rheo-SAXS, respectively). Under certain conditions, a unique pattern in Rheo-SIPLI: a Maltese cross combined with shear banding was observed. This phenomenon is unique to GO flakes of sufficiently large lateral size. The structure formed is attributed to a helical flow arising from a combination of shear flow and Taylor-vortex type flow, which is reinforced by a mathematical model. The orientations prescribed by this model are consistent with anomalous rheopecty oberved in Rheo-SIPLI and an anomolous scattering pattern in Rheo-SAXS. With the current trend towards producing ultra-large GO flakes, evidence that the flow behaviour changes from a Couette flow to a Taylor vortex flow was provided, which would lead to undesired, or alternatively, controllable alignment of GO flakes for a variety of applications, including aligned structures for biomedical purposes.
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Behof, William James. "Progress Towards the Synthesis of Novel Graphite Derivatives from a Solution Processable Poly-Cyano Precursor Polymer." NCSU, 2010. http://www.lib.ncsu.edu/theses/available/etd-12212009-134714/.
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In this thesis the synthetic progress towards the development of a novel potentially conducting ladder polymer, through the direct writing of a soluble precursor polymer, is presented. The proposed ladder polymer can be synthesized through three steps; the synthesis of a poly-cyano monomer for polymerization, the synthesis of a poly-cyano precursor polymer, and a one step cascading cyclization of a poly-cyano polymer. First addressed is the rather specific palladium catalyzed coupling conditions needed for a single C-C bond forming reaction of highly electron deficient aryl cyanides. The optimization of this coupling reaction, as performed on small oligomers, illustrates that the choice of metal catalyst, supporting ligand, and most especially base have a large influence on the yield. Secondly, a new, highly selective synthetic route to a desired monomer is presented. Third, the precursor polymer is synthesized through the application of the aforementioned optimal conditions. It is observed, through an optimization study, that the highest yielding test couplings do not yield the highest molecular weight polymer. Finally, three cyclization routes, of which only one is a cascading cyclization, are discussed. Photo-physical properties of the isolated fused ring systems show that the larger fused ring oligomers have modest bandgaps and are potential candidates as semi-conducting materials.
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Muhundan, Arumugam. "Effects of using graphing calculators with a numerical approach on students' learning of limits and derivatives in an applied calculus course at a community college." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001186.
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Tyborski, Christoph [Verfasser], Janina [Akademischer Betreuer] Maultzsch, Axel [Gutachter] Hoffmann, Ralph [Gutachter] Krupke, and Janina [Gutachter] Maultzsch. "Electronic and vibrational properties of diamondoid derivatives, graphite, and carbon nanotubes / Christoph Tyborski ; Gutachter: Axel Hoffmann, Ralph Krupke, Janina Maultzsch ; Betreuer: Janina Maultzsch." Berlin : Technische Universität Berlin, 2018. http://d-nb.info/1173247602/34.
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Nascimento, Leandro Fontanetti do. "Grafite funcionalizada em condições de Friedel-Crafts mediada por radiação de microondas: novo material para construção de eletrodos de pasta de carbono." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-04072007-151512/.
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A modificação e/ou a funcionalização de eletrodos têm por objetivos o desenvolvimento de métodos eficazes para a preparação de eletrodos quimicamente modificados (EQMs) que possam aliar melhorias em sua sensibilidade, seletividade e reatividade em relação aos eletrodos base. Entretanto, a estabilidade e a reprodutibilidade dos EQMs quanto ao processo de lixiviação dos modificadores precisam ser melhorados para que se possam obter eletrodos mais robustos com longo tempo de análise. Uma das possibilidades para se obter eletrodos mais estáveis é por meio de uma ligação estável do tipo covalente entre o eletrodo base e o modificador. Desta forma este trabalho tem por objetivo a funcionalização da grafite por meio de uma reação covalente entre os modificadores cloreto de 4-nitrobenzoíla (4-NB), cloreto de 3,4-dihidroxibenzoíla (3,4-DHB) e do cloreto de 2,2?-bipiridina 4,4?-dicarbonílico (2,2-BP) por meio de uma reação de acilação de Friedel-Crafts assistida por radiação de microondas. O material de síntese foi caracterizado por voltametria cíclica, espectroscopia de infravermelho, curvas termogravimétricas e térmicas diferenciais e espectroscopia de impedância eletroquímica em comparação com a mistura física entre a grafite e os modificadores. Além disso, realizou-se uma generalização da síntese de Friedel-Crafts para outros substratos carboníferos eletródicos como os nanotubos e as fibras de carbono, além de algumas aplicações dos materiais funcionalizados, como exemplos, a grafite funcionalizada e as fibras de carbono funcionalizadas com o derivado bipiridínico (GFT-2,2BP e CNF-2,2BP), por meio de uma ligação entre as bipiridinas funcionalizadas covalentemente nos materiais carboníferos e alguns complexos de rutênio tais como [Ru(bpy)2(OH2)2](PF6)2, [RuCl2(PPh3)3] e do precursor RuCl3.3H2O em eletrooxidações de compostos orgânicos. Para a grafite funcionalizada com nitro derivado (GFT-4NB), realizou-se a eletrooxidação de NADH sobre o potencial redox da hidroxilamina/nitroso. Os resultados dos experimentos de EIS demonstram que a grafite funcionalizada possui uma maior resistência que o material obtido por mistura física. Isto seria esperado já que a formação da ligação covalente afeta a deslocalização de elétrons pi. Finalmente esta metodologia seria uma plataforma geral para a preparação de grafite covalentemente modificada com derivados cujas moléculas possui aplicações de interesse. Assim, o material obtido por este método pode ser usado em aplicações como em eletrodos de pasta de carbono, eletrodos impressos, filmes finos e nanocompósitos e mesmo como um catalisador em reações químicas. Desde que a resposta eletroquímica é muito sensível ao eletrólito, este trabalho abriu uma larga variedade de estudos para entender a interação desses materiais no meio aquoso e orgânico.Modification and/or functionalization of eletrodic materials have been investigated in order to improve the application of chemically modified electrode (CME) regards on their sensitivity, selectivity and reactivity comparing with unmodified substrate. However, the stability and reproducibility of these CME are one of the most important goals to achieve mainly regarding on the lixiviation of the modifier molecule. Quimisorption is one way to obtain very stable modified materials, since the redox mediator is attached to the substrate by covalent bound. Still it is very important to study the stability and chemical reactivity of these materials. The aim of this work is to synthesize graphite, carbon nanotube and carbon fiber with 4-nitrobenzoíl chloride (4-NB), 3,4-dihidroxibenzoíl chloride (3,4-DHB) and 2,2-bipyridine- 4,4-dicarbonil chloride (2,2-BP) in Friedel-Crafts condition mediated by microwave radiation. The materials were characterized by cyclic voltammetry (CV), using carbon paste electrode (CPE), infrared spectroscopy (IR), thermo gravimetric (TG) and differential thermal analysis (DTA) and electrochemical impedance spectroscopy (EIS). All of the synthesized graphite derivatives were compared with the respective physical mixtures. Moreover, graphite derivatives with bipyridine were used as a ligand in the synthesis with [Ru(bpy)2(OH2)2](PF6)2, [RuCl2(PPh3)3] and RuCl3.3H2O. These products were used as electrocatalysts to oxidize alcohols in comparison with the complex incorporated in graphite. Graphite obtained from 4-NB reaction was employed to oxidize NADH in the redox potential of hydroxylamine/nitroso derived. Results from EIS measurements have show that graphite functionalized has higher resistance than the material obtained by physical mixture. This would be expected since the covalent bound would affect a pi electron dislocation. In conclusion, this methodology would be a general platform to prepare graphite and derivatives covalently bounded to molecules that have interesting application. In addition, it\'s been shown that the catalytic property of the respective function organic hasn\'s changed after reaction with carbon substrate. Thus the material obtained by this method could be used in applications such as carbon paste electrodes, finger print electrodes, thin films and nanocomposites and even as a catalyst in chemical reaction. Since the electrochemical response is very sensitive regards on the electrolyte, this work opened a wide range of studies to understand the interaction of these materials in aqueous and organic medium.
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Gonzalez, Vieyra Joel Abraham. "Estimation et Contrôle des Systèmes Dynamiques à Entrées Inconnues et Energies Renouvelables." Thesis, Ecole centrale de Lille, 2019. http://www.theses.fr/2019ECLI0012/document.
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De nos jours, les processus industriels se doivent d’être efficaces, en particulier au niveau de leur production et/ou consommation énergétique.Ce travail vise à améliorer l’efficacité des processus en analysant l’influence des perturbations sur leur comportement, de la phase de conception à la synthèse des contrôleurs/observateurs, ceci dans une approche intégrée.Le problème du Rejet de Perturbation est introduit ainsi que différents types de contrôles permettant d’atténuer et/ou rejeter ces perturbations. Le système de Barre de Torsion est présenté. Une loi de commande basée sur le concept d’état dérivé est présentée et ensuite validée avec comme application le rejet de perturbation. Il est nécessaire d’estimer les grandeurs physiques utilisées dans les différentes expressions de loi de commande. Un observateur à entrées inconnues basé sur la représentation bond graph est rappelé et ensuite étendu au cas multi-variable. C’est la première contribution théorique de ce travail de recherche.Nous comparons ensuite l’efficacité de différentes techniques de commandes pour le rejet de perturbation par simulation sur le système barre de torsion et analysons ainsi l’efficacité de la technique proposée. Une extension théorique au problème du découplage entrée-sortie nous permet de généraliser le problème du rejet de perturbation dans une même démarche intégrée d’analyse et de synthèse. Enfin, ces techniques sont exploitées et analysées sur le système réel. Nous validons ainsi expérimentalement nos résultats.Un modèle très simplifié de centrale hydroélectrique est développé afin d’appliquer les résultats de nos travaux. Un modèle bond graph simplifié est validé par simulationNowadays, industrial processes must be efficient, particularly at the production level and/or energy consumption.This research work aims at improving the process efficiency by analysing the influences of disturbances on their behaviour, from the conception phase to the synthesis of controller/observer, in an integrated approach.The disturbance rejection problem is first introduced as well as different control laws allowing attenuate/reject these disturbances. A control law based on the concept of derivative state variable is presented and validated while applied as disturbance rejection.In order to reject the disturbance, different physical variables must be estimated, such as state variables, derivative state variables as disturbance variables. An unknown input observer based on the bond graph representation is recalled and extended in the multivariable case. It is the first theoretical contribution of this work.We thus compare the efficiency of different so-called «modern control laws» for the disturbance rejection problems by simulation with the Torsion-Bar system example. We analyse the efficiency of our approach. One extension to the Input-Output decoupling problem allows us to extend the disturbance rejection problem to other control law type in an integrated approach. At least, these techniques are applied on the real Torsion-Bar system and compared. We validate our approach.Since this work aims at analysing and developing efficient control laws for industrial processes, a simplified model of a hydroelectric plant is developed, in order to apply our results. A simplified bond graph model is validated with simulations
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Chia-HaoTu and 凃嘉豪. "Growth and Characterization of Graphene and Its Derivatives." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/87093628030147137505.
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博士國立成功大學
材料科學及工程學系
103
The aim of this research is to investigate the growth mechanism of the synthesis of graphene related materials by various methods. The graphene related materials include monolayer graphene snowflake, porous graphenic carbon film, composite of carbon nanorod on porous graphenic carbon film, and graphene nanowalls. First, chemical vapor deposition is employed to grow large single-domain graphene snowflakes (〉 0.5 mm2) on Cu foil by crossing numerous Cu grain boundaries underneath. The orientation of the graphene snowflake branches is preserved when crossing the Cu grain boundaries, as evidenced by Raman spectra and transmission electron microscopy analysis. Diffraction patterns and scanning electron microscopy images reveal a relationship between the growth front and the orientation of graphene snowflakes. The graphene snowflake branch portions before and after crossing a Cu grain boundary show similar effective field-effect mobilities, confirming that the orientation did not change. Diffraction patterns of graphene and electron backscattering diffraction maps of Cu grains are used to study graphene lattice overlap below Cu grains. The orientation of Cu grains has little influence on the growth of top graphene snowflakes, probably due to the weak bonding interaction between Cu grains and graphene, constraining the growth of graphene snowflakes at temperatures close to the melting point. Second, a method is developed for growing three-dimensional hierarchic structures of porous graphenic carbon film/ hollow carbon nanorods where porous graphenic carbon film is first synthesized followed by, growth of carbon nanorods. Porous graphenic carbon films were synthesized by solid-state diffusion on nickel thin film. By annealing an amorphous carbon layer deposited underneath a nickel thin film at elevated temperatures, the porous graphenic carbon film forms on top via carbon diffusion and precipitation from the grain boundaries of the nickel film. Hollow carbon nanorods can then be grown on the pore edges of the porous graphenic carbon film by chemical vapor deposition without catalysts. It is speculated that the dangling bonds of the carbon atoms on the pore edges of the graphene layers might be responsible for the nucleation of the hollow carbon nanorods. The microstructures and growth mechanisms of both porous graphenic carbon film and hollow carbon nanorods are characterized and discussed in detail. Finally, carbon nanowalls were successfully grown on Si(001) wafer by direct-current plasma enhanced chemical vapor deposition. Carbon nanowalls, standing structure of graphene sheets, are vertical to substrate. Heteroepitaxial nucleation of {002} graphene sheets on {111} facets of plasma treated (100) silicon is confirmed by high-resolution transmission electron microscopy. Lattice mismatch by 12% is compensated by tilting the graphene {002} with respect to silicon {111} and matching the silicon lattice with fewer graphene layers. The interlayer spacing of graphene sheets near the silicon surface is 0.355 nm, which is larger than that of AB stacked graphite and confirmed as AA stacked graphitic phase. A strong Raman peak corresponding to silicon-hydrogen stretch vibration is detected by 633 nm excitation at the early stage of graphene nucleation, indicating the silicon substrate etched by hydrogen plasma. With these analyses, the growth mechanism is also proposed.
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WANG, SHIH-HSUAN, and 王世軒. "Au/Graphene Derivatives Nanohybrids for Photo-thermal and Anti-bacterial Application." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/55178238828445741857.
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Huang, Jian Xiang, and 黃健翔. "Study of N-doped graphene grown on Cu(100) from pyridine derivatives by using Raman spectroscope." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/67623693295387242798.
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碩士國立高雄師範大學
物理學系
103
ABSTRACT N-graphene shows different properties; for example, the Femi level is higher than Dirac point, band gap is not zero, and carbon is activated by neighbor nitrogen dopants which influences the spin density and charge distribution of carbon atoms. These make N-graphene promising for various applications such as semiconductors, solar cell, sensor, lithium ion batteries and electrocatalyst for fuel cell. Therefore, preparation of N-graphene growth is an important issue. In this work ,we study N-doped graphene grown from pyridine derivatives chemical vapor deposition on Cu(100) in ultra high vacuum system by using in situ Raman spectroscopy and low energy electrondeflection(LEED). In graphene generation temperature and a two-step variable temperature experiments, it shows that sp2 carbon cluster is formed while dosing temperature above 850K. Nano N-graphene is formed from dosing at 1000K to 1050K. It becomes larger and defectless when dosing temperature above 1100K, however it’s doping level is significant reduction. From coverage dependant and LEED observation, we found that graphene growth on Cu is self-limited, formed monolayer multi-orientation graphene, and mainly growing with four orientation. Finally, we found that our in situ Raman ratio IG’/IG is small as well as G and G’ band of monolayer graphene prepared from 3,5-DBP 2,4-DBP and 1,3-diidobenzene are blue shift compared to those monolayer graphene transferred in literatures. These phenomenon is mainly caused by the interaction between grapheme and copper substrate, the interaction also affect the Raman spectrum of temperature dependence. The value of temperature coefficients of the G band frequency of N-graphene grown on Cu(100) at 1000K 1050K and 1100K respectively, is not affected by the presence of D band. Our work shows that graphene can grown on Cu(100) surface at 1100K by ultra high vacuum chemical vapor deposition with 3,5-DBP,2,4-DBP as precursor, as well as N-graphene can grown at 1050K.
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Akther, Nawshad. "Development of Thin-Film Composite Membranes Incorporated With Graphene Oxide and Derivatives for Forward Osmosis Processes." Thesis, 2020. http://hdl.handle.net/10453/149327.
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University of Technology Sydney. Faculty of Engineering and Information Technology.Graphene oxide (GO) has been used to improve the anti-fouling and separation performance of the thin-film composite (TFC) membranes. Nonetheless, very few studies provided an in-depth explanation of the possible interaction between GO and polymer matrix that alter the membrane properties and performance. Thus, the overall aim of this study was to develop high-performance GO-based polyamide (PA) TFC forward osmosis (FO) membranes by systematically investigating the effect of GO and its derivatives on the modified membranes. First, polyvinyl alcohol (PVA)/GO hydrogel was coated on the PA surface to improve the membrane anti-fouling property. Second, the GO flake’s lateral size was reduced to decrease PA defects and improve membrane performance. Next, Aquaporin was added with GO in the PA layer to improve the membrane selectivity as Aquaporin healed the non-selective PA defects created by the GO flakes. Finally, the effect of GO quantum dots (GQDs) on the interfacial polymerization (IP) reaction and membrane performance at both macroscopic and microscopic levels was investigated both experimentally and using molecular dynamics (MD) simulation. GQDs decreased the IP reaction rate by reducing the diffusivities of PA monomers, reduced water permeability by acting as barriers to water molecules when present at a high concentration near the PA surface, and formed non-selective voids at the PA layer when present at very high loading.
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Huang, Jhong-Yi, and 黃仲逸. "Inverted planar perovskite solar cells based on derivative of Graphene oxide and reduced-Graphene oxide Electrode." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/38f7ab.
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碩士國立交通大學
應用化學系碩博士班
105
Graphene oxide (GO) and its derivatives as the promising hole-extracting layer (HEL) are used for inverted planar heterojunction (PHJ) perovskite solar cells(PSC). The effect of GO reduction conditions on hole extraction properties is studied. We synthesized reduced graphene oxides (rGO) of three types – rGO-NH, rGO-BH, rGO-HBS – via reduction of GO with reducing agents – hydrazine, sodium borohydride and 4-hydrazino- benzene sulfonic acid – as HEL. The devices fabricated by reduced graphene oxides show the higher photovoltaic performance attaining power conversion efficiency (PCE) 16.0 %, 16.4 % and 15.3 under AM 1.5 G one-sun irradiation , which is superior than GO with PCE 13.8%. Moreover, the flexible solar cell based on rGO shows high PCE of 13.8% and this device is robust against bending and can maintain its efficiency under bending situation. Based on the controlled experiment, it was found that the trap states on GO and rGOs play a significant role. The lower performance of GO is related to its insulating properties of nanosheets. Film formation and coverage of the substrate by graphene nanosheets as the determinant factor was realized.
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Candrawan, Julius, and 陳健輝. "Selective Electrochemical Detection of Metal Ions by Porphyrin Derivative/Graphene Derivative Thin Films on ITO Electrode." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/31816139651614706594.
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碩士國立臺灣科技大學
化學工程系
102
Nanotechnology has been extensively utilized in many field of applications, such as sensors. This research reported about preparation of porphyrin derivative/graphene derivative composite and their sensor application. Porphyrin derivative used in this research was tetrakis(4-carboxyphenyl)porphyrin (TCPP), whereas graphene derivatives used were graphene oxide (GO) and reduced graphene oxide (RGO). It began with a synthesis of composite (GO-TCPP) by non-covalent strategy through aromatic ??{? stacking and a synthesis of reduced graphene oxide through chemical reduction method. Optical, electrical, and morphological properties of each solution showed acceptable results, indicating self-assembly monolayer and electron transfer process in the presence of electron acceptor and donor. The preparation of thin films on ITO electrode was carried out via self-assembled monolayer method. APTES was used as a functional group to perform chemical bonding between ITO electrode and porphyrin derivative/graphene derivative. Preparation of each thin film by using APTES as a self-assembled monolayer functional group used 24 hours as an immersion time. Cyclic voltammetry results indicated that GO-TCPP/APTES/ITO electrode has higher conductivity than TCPP/RGO/APTES/ITO electrode. The selective detection of metal ions (Cu2+, Zn2+, and Fe2+) were investigated through spectrophotometry and electrochemical determination method. According to the result of spectrophotometry and electrochemical determination, TCPP have selective detection to Cu2+ ions because TCPP have pyrrole ring and carboxyl groups which play an important role to bind Cu2+ ions. GO composite (GO-TCPP) give the greatest electrochemical behavior to Cu2+ ion since the characteristic of GO as a conductive material could accelerate electron transfer process which related to enhancement of sensitivity performance to Cu2+ ions.
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Chang, Ya-Ming, and 張雅茗. "Investigation on the pervaporation performance of PVA/Graphene derivative hybrid membrane." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/36953089067316653065.
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碩士中原大學
化學工程研究所
104
The hydrophilic graphene oxide (GO) is generally used to be nanocomposite materials by mixing it with polymer. But large amounts of strong acid and oxidants during GO synthesis produces environmental pollutants. In this study, we prepared an environmentally friendly nanocomposite materials through modified graphene(mGr) with dopamine for dehydration process of ethanol. PVA-mGr hybrid membranes were fabricated for pervaporation application by adding mGr in the PVA solution. The physicochemical properties, structure, and hydrophilicity of the fabricated membranes were characterized by attenuated total reflection - Fourier transform infrared spectroscopy (ATR-FTIR), water contact angle measurement, field-emission scanning electron microscope (FE-SEM) and x-ray diffraction techniques (XRD). The improvement of the physicochemical properties and pervaporation performance of the hybrid membranes are presumably due to the effect of nanoscale structure and the interaction between polymer and inorganic material. Graphene agglomerates because of Van der Waals forces between graphene layers. The mGr does not agglomerates since the hydrophilicity was increased because of the Gr modification with dopamine. The effect of the content of graphene derivatives on pervaporation performance were investigated. The results showed that PVA-mGr hybrid membranes had excellent performance when added with 3 wt% mGr in the separation of 90 wt% aqueous ethanol solution at 25 ℃. The permeation flux and water concentration in permeate side of PVA-mGr membranes were 359 g/m2-h and 98.4 wt%, respectively. This study also investigated the effects of pervaporation conditions, including feed temperature, feed concentration, and durability test on pervaporation separation. Compared with PVA membrane, the hybrid membrane could effectively suppress swelling and enhance the stability of membranes. At a high feed temperature of 70℃, the water concentration in permeate side was 83 wt%, and the permeation flux was 982 g/m2 h. The membrane life of pervaporation process through the durability test for 90 wt% aqueous ethanol solution. After 22 days, the water concentration in permeate side and permeation flux of PVA-3mGr and PVA-3Gr membranes were remained at 97 wt%, 93 wt% and 537 (g/m2 h), 356 (g/m2 h) respectively.
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Teck-HouTiong and 張德豪. "Application of graphene and its derivative for molecularsensing by Surface Enhanced Raman Scattering." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/69821825274110404521.
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碩士國立成功大學
微電子工程研究所碩博士班
101
We demonstrate the suppression of gold-nanoparticle induced surface-enhanced Raman scattering (SERS) by single layer graphene(Gr)on gold nanoparticles (AuNPs). Although electric fields perpendicular to Gr surface can easily penetrate through Gr,electric fields near the surface of a conductive Gr and in directions parallel to the substrate surface are weak, resulting in measured SERS signal intensity from molecules adsorbed on the Gr surface to be suppressed. The high resistivity of the Gr after subjecting to remote plasma hydrogenation allows plasmonic coupling induced strong local electromagnetic fields among the gold nanoparticles to penetrate the Gr, and thus enhances the SERS efficiency of R6G molecules adsorbed on the Gr film. In this thesis, we also report evidences of progressively increasing SERS signal intensity, due to increasing electrical resistivity of Gr with its exposure time to remote hydrogen plasma,of R6G molecules on Gr covered AuNPs which are deposited on an oxidized silicon chip.
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Tai, Ching-Ting, and 戴晶婷. "Fabrication and application of a-Ni(OH)2/graphene derivative and a-Ni(OH)2/exfoliated montmorillonite composites and their hybrids for high-performance supercapacitor electrodes." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/53361445802566999606.
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碩士國立臺灣大學
材料科學與工程學研究所
105
In recent years, supercapacitor has attracted significant attention by its superior performance such as high specific power, long lifecycle, short charging time, and environment-friendly. To improve the specific energy, rate capability, and cycle stability of electrode materials for supercapacitor, in this thesis a facile one-step solution precipitation method was conducted to prepare 3D structural Al-Ni(OH)2 composites in a-phase. The composites are composed of Al-Ni(OH)2 and 2D supporting additives (graphene oxide, reduced graphene oxide, modified graphene oxide with positive charges, modified reduced graphene oxide, and exfoliated montmorillonite). In addition, the “Al-Ni(OH)2 composite hybrid” as a final product is made by mixing with two composites: graphene-based materials/Al-Ni(OH)2 and exMMT/Al-Ni(OH)2, and it provides new properties and high performance. The 2D supporting additives are prepared by the following methods. The graphene oxide (GO) is prepared by modified Hummers method and then reduces it with hydrazine as reducing agent to obtain reduced graphene oxide (rGO). The functionalized GO and rGO with positive charges (GO+ and rGO+, respectively) was made by chemical modification with ethylenediamine. Furthermore, the exfoliated montmorillonite (exMMT) is fabricated through soap-free emulsion polymerization of methyl methacrylate (MMA) in the presence of montmorillonite. The Al-Ni(OH)2 based composites are fabricated by controlling the additives mass ratio with 0.8%, 1.59%, 3.13%, and 6.09%. XRD, TEM, SEM, Raman, and electrochemical measurements including GCD, CV, and EIS are used to characterize the Al-Ni(OH)2 based materials. The surface morphology of those composites with negatively charged substrates (GO, rGO, and exMMT) were a 3D open-porous nanostructure constructed by randomly decorated Al-Ni(OH)2 nanosheets as building blocks. Whereas, for those with positively charged substrates (GO+ and rGO+), the relatively flat structure was observed. Among these composites, the best one was 1.59% GO/Al-Ni(OH)2 (GO accounts for 1.59wt% of this composite) with 2759.32 F/g at 1A/g and 1279.94 F/g at 20A/g with a capacitance retention of about 46%. The specific capacitance at 1 A/g and 20 A/g were 30% and 70% higher than that of pure Al-Ni(OH)2, respectively. This improved capacitance could be explained by both the increasing effective redox areas related to 3D porous morphology and enhanced conductivity by incorporating graphitic sheet. In the hybrid system, the exMMT/Al-Ni(OH)2 and rGO+/Al-Ni(OH)2 hybridized in 1:1 mass ratio showed the highest specific capacitance with 2498.81 F/g at 1A/g and retained 1760.76 F/g at 20A/g with a significantly improved capacitance retention of about 70%. Note that after the hybrid process, Rct dramatically decreased and almost equaled to the Rct of 1.59% GO/Al-Ni(OH)2. It is presumable that exMMT nanosheets would raise ionic transportability and rGO+ sheets enhanced electrical conductivity. Therefore, such Al-Ni(OH)2 hybrid is an excellent choice for high-performance supercapacitor electrode.
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Ke, Yi-Chun, and 柯怡君. "Part-1 Nanogold particle-fabricated graphene oxide derivative for tissue engineering application;Part-2 To evaluate the delivery capacity of gold nanoparticles conjugated with stromal cell derived factor – 1α on Mesenchymal stem cells." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/gxkb7h.
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