Rozprawy doktorskie: „Reduced graphene oxide”

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Nyangiwe, Nangamso Nathaniel. "Graphene based nano-coatings: synthesis and physical-chemical investigations". Thesis, UWC, 2012. http://hdl.handle.net/11394/3237.

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Magister Scientiae - MSc
It 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.

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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.

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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.

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Kim, K. B., J. G. Kim, H. K. Kim, J. P. Jegal, K. H. Kim, J. Y. Kim i S. H. Park. "Nanocomposites of Reduced Graphene Oxide for Energy Storage Applications". Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35266.

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A well-crystallized and nano-sized Metal oxide/reduced graphene oxide composite material for lithium ion batteries has been successfully synthesized. The nano-sized metal oxide particles were evenly dispersed on the reduced graphene oxide template without any agglomeration, which allows the inherent high active surface area of individual metal oxide nano-particles in the composite. These unique structural and morphological properties of metal oxide on the highly conductive reduced graphene oxide sheets in the composite enable achieving the high specific capacity, and excellent high rate capability and stable cycling performance. an analysis of the cyclic voltammogram data revealed that a large surface charge storage contribution of the metal oxide/reduced graphene oxide nanocomposite plays an important role in achieving faster charge/discharge. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35266

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Al-Nafiey, Amer Khudair Hussien. "Reduced graphene oxide-based nanocomposites : synthesis, characterization and applications". Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10009/document.

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Nous avons synthétisé avec succès ces nano-composés (rGO/Arg-Ag NPs, rGO-Ni NPs and rGO-Co3O4NPs) et les avons caractérisés par de nombreuses techniques, XPS, SEM, TEM, FTIR, Raman, UV-Vis et TGA. Les analyses montrent que ces nano-composés à base de graphène ont des propriétés excellentes et une grande stabilité. Utilisés comme catalyseurs dans des applications environnementales, ils réduisent efficacement le 4-nitrophenol en 4-aminophenol ainsi que les colorants à forte adsorption et le chrome (VI) présents dans les eaux usées
We successfully obtained these nanocomposites (rGO/Arg-Ag NPs, rGO-Ni NPs and rGO-Co3O4NPs).The resulting rGO-based nanocomposites were characterized by a variety of different techniques, including XPS, SEM, TEM, FTIR, Raman, UV-Vis and TGA. These analysis shows that these graphene-based nanocomposites have excellent properties and stability. The rGO-based nanocomposites, applied as a catalyst in environmental applications and shows good catalytic performance for reduction of 4nitrophenol to 4aminophenol and high adsorption dyes and Cr (VI) from wastewater

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Chari, Tarun. "Reduced graphene oxide based transparent electrodes for organic electronic devices". Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104534.

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This thesis explores the utility of reduced graphene oxide and hybrid reduced graphene oxide/single walled carbon nanotubes as a transparent electrode. Graphene oxide was fabricated using the modified Hummers method, transferred to arbitrary substrates by a vacuum filtration method, and reduced chemically and thermally thus creating thin, large area reduced graphene oxide films. Films were characterized electrically, optically, spectroscopically, and topographically. Raman and X-ray photoelectron spectroscopy techniques were utilized to ensure successful fabrication of reduced graphene oxide. The reduced graphene oxide electrodes exhibit sheet resistances on the order of 10 – 100 kΩ/sq with transparencies between 60 – 90 %. To ameliorate these electronic properties, single walled nanotubes were introduced during the filtration process to separate the graphene oxide nanoplatelets and prevent structural deformation during reduction. This nanotube doping yielded a two-fold decrease in sheet resistance for low nanotube to graphene oxide ratios, but increased sheet resistance for higher nanotube to graphene oxide ratios. Reduced graphene oxide electrodes and nanotube/reduced graphene oxide hybrid electrodes were used in organic light emitting diode and organic solar cell applications. Organic light emitting diodes exhibited current efficiencies of about 1 cd/A and organic solar cells exhibited power conversion efficiencies less than 1 % for both reduced graphene oxide and hybrid electrodes.
Cette thèse examine l'utilité de l'oxyde de graphène réduit et de l'hybride oxyde de graphène réduit et nanotubes carbone en fonction d'une utilisation comme électrode transparente. L'oxyde de graphène a été fabriqué par la méthode de Hummers modifié puis a été transféré sur un substrat arbitraire par la méthode de filtration avec suction à vide, et a été réduit chimiquement et thermiquement pour créer des feuilles d'oxyde de graphène réduit qui sont minces et qui couvrent une grande surface. Les feuilles ont été caractérisées par des mesures électriques, optiques, spectroscopiques, et topographiques. Les spectroscopies Raman et par photoélectron induits par rayons-X ont été utilisées pour s'assurer que la fabrication de l'oxyde de graphène reduit a été obtenue. Les électrodes d'oxyde de graphène reduit montrent des résistances de feuille de 10– 100 kΩ/sq avec des transparences entre 60 – 90 %. Pour améliorer ces propriétés, des nanotube de carbone monoparois ont été introduits pendant le processus de filtration pour séparer les nanoplatelets d'oxyde de graphène et pour éviter la déformation structurelle pendant la processus de réduction. Ce dopage de nanotubes a diminué la résistance de feuille par un facteur deux pour des proportion faibles de nanotubes avec l'oxyde de graphène, mais a augmenté la resistance pour les hautes proportions. Les électrodes d'oxyde de graphène reduit et les électrodes hybrides nanotubes/oxyde de graphène reduit ont été utilisées dans des dispositifs optoélectroniques organiques; spécialement des diodes électroluminescentes et des cellules solaires. Les diodes électroluminescentes organiques ont des rendements de courant inferieurs à 1 cd/A et les cellules solaire ont des rendements de puissance inferieurs à 1 % pour les deux types d'életrodes: oxyde de graphène réduit et hybrides.

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Joung, Daeha. "Electronic Transport Investigation of Chemically Derived Reduced Graphene Oxide Sheets". Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5332.

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Reduced graphene oxide (RGO) sheet, a chemically functionalized atomically thin carbon sheet, provides a convenient pathway for producing large quantities of graphene via solution processing. The easy processibility of RGO sheet and its composites offer interesting electronic, chemical and mechanical properties that are currently being explored for advanced electronics and energy based materials. However, a clear understanding of electron transport properties of RGO sheet is lacking which is of great significance for determining its potential application. In this dissertation, I demonstrate fabrication of high-yield solution based graphene field effects transistor (FET) using AC dielectrophoresis (DEP) and investigate the detailed electronic transport properties of the fabricated devices. The majority of the devices show ambipolar FET properties at room temperature. However, the mobility values are found to be lower than pristine graphene due to a large amount of residual defects in RGO sheets. I calculate the density of these defects by analyzing the low temperature (295 to 77K) charge transport data using space charge limited conduction (SCLC) with exponential trap distribution. At very low temperature (down to 4.2 K), I observe Coulomb blockade (CB) and Efros-Shklovskii variable range hopping (ES VRH) conduction in RGO implying that RGO can be considered as a graphene quantum dots (GQD) array, where graphene domains act like QDs while oxidized domains behave like tunnel barriers between QDs. This was further confirmed by studying RGO sheets of varying carbon sp2 fraction from 55 – 80 % and found that both the localization length and CB can be tuned. From the localization length and using confinement effect, we estimate tunable band gap of RGO sheets with varying carbon sp2 fraction. I then studied one dimensional RGO nanoribbon (RGONR) and found ES VRH and CB models are also applicable to the RGONR. However, in contrast to linear behavior of decrease in threshold voltage (Vt) with increasing temperature (T) in the RGO, sub linear dependence of Vt on T was observed in RGONR due to reduced transport pathways. Finally, I demonstrate synthesis and transport studies of RGO/nanoparticles (CdS and CeO2) composite and show that the properties of RGO can be further tuned by attaching the nanoparticles.
Ph.D.
Doctorate
Physics
Sciences
Physics

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SAVAZZI, FILIPPO. "Computational study of reduced Graphene Oxide properties for membrane applications". Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2903478.

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Ammar, Ali M. "REDUCTION OF GRAPHENE OXIDE USING MICROWAVE AND ITS EFFECT ON POLYMER NANOCOMPOSITES PROPERTIES". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1533123263694685.

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Lu, Xiaoling [Verfasser]. "Reduced Graphene Oxide Biosensors for Prostate Cancer Biomarker Detection / Xiaoling Lu". Gießen : Universitätsbibliothek, 2019. http://d-nb.info/1189582759/34.

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Wu, Zhenkun. "Metal-reduced graphene oxide for supercapacitors and alternating current line-filters". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53941.

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We design a facile approach to investigate the role benzene derivatives play in the capacitance enhancement of graphene-based supercapacitors. The main reason is attributed to the pseudocapacitance of the aromatic molecules rather than the former one. Meanwhile, we find that the para and ortho substituted benzene derivatives contribute much more than the meta substituted ones. In addition, we fabricate an all-solid-state flexible MSC based on metal-reduced GO. The as-fabricated MSC shows high areal capacitance and excellent reliability, which makes it a promising energy storage candidate for wearable electronics. Based on the work of MSC, we achieve a flexible ac line-filter that is not only competitive against commercial product but also suitable for mass production. Meanwhile, we produce a three-dimensional graphene/polydimethylsiloxane composite that gives a thermal resistance as small as 14 mm2K/W, which is comparable to commercial products. What’s more, a convenient transient program that saves much time is developed to measure the thermal resistance.

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Bai, Xiaoyun. "Development of reduced graphene oxide based nanocomposities for electrochemical biosensing applications". HKBU Institutional Repository, 2014. https://repository.hkbu.edu.hk/etd_oa/228.

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The modification of electrodes is always an important task in electrochemical detection of electroactive and biological molecules. Chemically modified electrodes can offer improved selectivity and sensitivity for the target analyte, which greatly enhance the electrode performance. Various materials such as conducting polymers, metal nanoparticles and carbon nanomaterials have been exploited and widely used for the modification of electrodes. Electrochemical or spontaneous deposition, electrostatic adsorption, layer-by-layer self assembly and covalent binding have also been developed for electrode modification and offer improved performance. Both Prussian blue (PB) and toluidine blue O (TBO) are excellent redox mediators and very popular in electrode modification. PB has shown strong catalytic property for the reduction of hydrogen peroxide, but the application in biosensor fabrication is limited for its instability at neutral pH. Graphene, as a single-atom-thick carbon material, is considered an ideal platform for designing composite nanomaterials for high-performance electrochemical or electrocatalytic devices. The combination of PB with reduced graphene oxide (RGO) and poly(toluidine blue O) (PTBO) will greatly improve the stability of PB. An amperometric biosensor based on glassy carbon (GC) electrode modified with reduced graphene oxide, PB and poly(toluidine blue O) was developed. Experimental results showed that the GC/RGO/PB/PTBO modified electrode offered an excellent electrocatalytic activity toward the reduction of hydrogen peroxide due to the possible synergistic effects of the PB-PTBO composite material. After codeposition of glucose oxidase (GOD) and chitosan (CHIT) coating, the resulting GC/RGO/PB/ PTBO/CHIT-GOD electrode exhibited excellent response to glucose with a sensitivity of 59 mA M1 cm2, a low detection limit of 8.4 μM and a linear range from 0.02 to 1.09 mM at a detection potential of +0.2 V vs. Ag.

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Salimian, Maryam. "Advances in multifunctional nickel/reduced graphene oxide nanocomposites, synthesis and characterization". Doctoral thesis, Universidade de Aveiro, 2018. http://hdl.handle.net/10773/23709.

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Doutoramento em Engenharia Mecânica
O grafeno é constituído por uma monocamada de átomos de carbono dispostos numa espécie de rede hexagonal perfeita. Devido às suas propriedades extraordinárias, este nanomaterial tem suscitado um grande interesse tanto no setor científico como no industrial. A este respeito, a investigação em torno do grafeno mostrou um aumento exponencial em áreas tão diferentes como a energia, biomedicina, eletrónica, entre outras. O óxido de grafeno (GO), um dos derivados de grafeno, foi considerado como um substrato interessante para o desenvolvimento de nanocompositos. Isto deve-se fundamentalmente à presença de grupos funcionais de oxigénio na superfície do grafeno, os quais proporcionam locais reativos para a nucleação e o crescimento de outras estruturas. O níquel (Ni) é um metal de transição muito abundante na terra, possui uma superfície brilhante comum à maioria dos metais e é dúctil e maleável possuindo propriedades magnéticas e catalíticas superiores, condutividade térmica e elétrica razoáveis sendo muito utilizado em diferentes aplicações. As nanopartículas (NPs) de Ni são utilizadas como catalisadores heterogéneos e receberam atenção notável devido ao seu baixo custo, reduzida toxicidade, baixa corrosão, entre outras características. Desta forma, a funcionalização do GO com NPs de Ni pode constituir uma nova família de nanocompósitos com propriedades sinérgicas. Esta tese está focada no controlo da síntese de nanocompósitos Ni/GO, uma vez que o tamanho, a morfologia e a dispersão de NPs de Ni no grafeno afetam as suas funcionalidades e estão em dependência direta com as metodologias de síntese. Em primeiro lugar, foi usado um método hidrotérmico de fácil implementação e execução num passo único. Foram estudados vários parâmetros de síntese, incluindo temperatura, tempo de reação e agente redutor. O controlo destes parâmetros influenciou efetivamente o tamanho das NPs de Ni, variando estas de 150 a 900 nm, a morfologia variou de forma esférica a formato em espiga e de partículas finas bem distribuídas para agregados. Em seguida, o controlo do tamanho das NPs de Ni para valores inferiores a 10 nm e com distribuição de tamanho reduzido no substrato foi conseguido através de um procedimento de síntese em dois passos com base num método solvotérmico seguido por tratamento térmico sob atmosfera redutora de H2. O tempo de reação mostrou ser um fator chave para controlar a distribuição e o tamanho das NPs de Ni simultaneamente com a redução do GO (rGO). O aquecimento em atmosfera de H2 foi crucial para formar as NPs de Ni metálicas cristalinas. A influência de um tratamento térmico adicional em atmosferas redutora e inerte sobre a estrutura do nanocompósito Ni/rGO foi também investigada. Diferentes nanocompósitos apresentaram boa estabilidade térmica sob H2 até à temperatura de 450 °C durante 2 horas. O tratamento a 900 °C sob o fluxo de árgon alterou a estrutura do Ni/rGO por formação de “sulcos” através da rede de carbono e coalescência das NPs de Ni com formação de partículas maiores. O estudo das propriedades eletrofisicas dos nanocompositos Ni/rGO mostrou que estas são dependentes do tamanho e estrutura das NPs de Ni nas folhas de rGO. Esta é uma potencial vantagem do método de síntese desenvolvido para o design de diferentes nanocompositos de Ni/rGO que poderão ser materiais favoráveis para aplicação em dispositivos eletrónicos integrados.
Graphene, the world thinnest material made of carbon atoms in a dense honeycomb network has captured a great interest in both scientific and industry sectors due to its remarkable properties. In this regard, the graphene research is facing an incredible rise in different areas such as energy, biomedical, sensor and electronic applications, between others. Graphene oxide (GO), one of the graphene derivatives, has been considered as an interesting substrate to build nanocomposites. This is due to the presence of oxygen functionalities at the graphene surface which provides reactive sites for the nucleation and growth of other structures. Nickel (Ni) is a transition metal very abundant on earth, it has a shiny surface common to most metals and is both ductile and malleable possessing different properties such as superior magnetic and catalysis properties, a fairly good heat and electrical conductivity and is widely used in different areas of application. Ni nanoparticles (NPs) find use as heterogeneous catalyst and received noteworthy attention because of its inexpensive, non-toxic, low corrosion, waste minimization, between other characteristics. In this way, the functionalization of GO with Ni NPs can establish a new family of nanocomposites with synergic properties. This thesis is focused on the control of the synthesis of Ni/GO nanocomposites, since the size, morphology and dispersion of Ni NPs on graphene affect their functionalities and are in direct dependence with the synthesis methodologies. First, a facile one pot hydrothermal method was introduced and various synthesis parameters including temperature, reaction time and reducing agent were investigated. The control of these parameters effectively influenced the Ni size, ranging from 150 to 900 nm, the morphology from spherical to spiky shape and from well distributed fine particles to the big aggregation. Then, the control of the Ni NPs size to values of less than 10 nm with narrow size distribution on the substrate was achieved via a two-step synthesis procedure based on a solvothermal method followed by a heat treatment under H2 reducing atmosphere. The reaction time was shown to be a key factor to control the size and size distribution of Ni NPs simultaneously through the reduction of GO (rGO). Heating treatment under H2 was crucial to form the crystalized metallic Ni NPs. The influence of further thermal treatment under reducing and inert atmospheres on the structure of Ni/rGO nanocomposite was also investigated. Different nanocomposites showed a good thermal stability under H2 up to 450°C during 2 hours’ treatment. Higher temperature (900°C) under Argon flow changed the structure of Ni/rGO by formation of trenches through the carbon etching and coalescence of Ni NPs to form bigger particles. The study of the electrophysical properties of Ni/rGO showed that these properties are dependent on the size and structure of Ni NPs on rGO nanosheets. This is the potential advantage of the synthesis method developed for designing different matrix of Ni/rGO nanocomposites which could be a favorable material for integrated electronic devices application.

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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.

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>Magister Scientiae - MSc
This 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

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Wang, Zegao, Pingjian Li, Yuanfu Chen, Jiarui He, Wanli Zhang, Oliver G. Schmidt i Yanrong Li. "Pure thiophene–sulfur doped reduced graphene oxide: synthesis, structure, and electrical properties". Royal Society of Chemistry, 2014. https://tud.qucosa.de/id/qucosa%3A36294.

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Here we propose, for the first time, a new and green ethanol-thermal reaction method to synthesize highquality and pure thiophene–sulfur doped reduced graphene oxide (rGO), which establishes an excellent platform for studying sulfur (S) doping effects on the physical/chemical properties of this material. We have quantitatively demonstrated that the conductivity enhancement of thiophene–S doped rGO is not only caused by the more effective reduction induced by S doping, but also by the doped S atoms, themselves. Furthermore, we demonstrate that the S doping is more effective in enhancing conductivity of rGO than nitrogen (N) doping due to its stronger electron donor ability. Finally, the dye-sensitized solar cell (DSCC) employing the S-doped rGO/TiO₂ photoanode exhibits much better performance than undoped rGO/TiO₂, N-doped rGO/TiO₂ and TiO₂ photoanodes. It therefore seems promising for thiophene–S doped rGO to be widely used in electronic and optoelectronic devices.

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Kushch, S. D., N. S. Kuyunko, A. A. Arbuzov, N. N. Dremova i V. E. Muradyan. "Pt supported on reduced graphite oxide catalysts for H2 activation". Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35570.

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Platinum catalysts of H2 activation with average size ≤2.0 nm were prepared in a base of reduction conversion of graphene oxide. A low few-layered carbon nanomaterial was prepared by thermoexpansion and annealing of graphene oxide. The uniformly dispersed Pt nanoparticles were supported on two-dimension graphene flat material by the use of pyridine or polyethyleneimine in alkaline (pH10) media as chelating agent modificating both metal precursor H2PtCl6 and support. Vacancies in carbon material formed as a result of thermoexpansion and annealing of graphite oxide probablly serve as anchor groups in platinum supporting. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35570

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Morselli, Serena. "Thermally reduced Graphene Oxide: a well promising way to transparent flexible electrodes". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9324/.

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L'elaborato tratta dell'ottimizzazione del processo di riduzione termica dell'ossido di grafene in termini di conduttività e trasmittanza ottica. Definiti gli standard di deposizione tramite spin-coating e riduzione termica, i film prodotti vengono caratterizzati tramite XPS, AFM, UPS, TGA, ne vengono testate la conducibilità, con e senza effetto di gate, e la trasmittanza ottica, ne si misura l'elasticità tramite spettroscopia di forza, tutto al fine di comprendere l'evoluzione del processo termico di riduzione e di individuare i parametri migliori al fine di progredire verso la produzione di elettrodi flessibili e trasparenti a base di grafen ossido ridotto.

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Chunder, Anindarupa. "FABRICATION OF FUNCTIONAL NANOSTRUCTURES USING POLYELECTROLYTE NANOCOMPOSITES AND REDUCED GRAPHENE OXIDE ASSEMBLIES". Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3082.

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A wide variety of nanomaterials ranging from polymer assemblies to organic and inorganic nanostructures (particles, wires, rods etc) have been actively pursued in recent years for various applications. The synthesis route of these nanomaterials had been driven through two fundamental approaches - Â Top downÂ and Â Bottom upÂ . The key aspect of their application remained in the ability to make the nanomaterials suitable for targeted location by manipulating their structure and functionalizing with active target groups. Functional nanomaterials like polyelectrolyte based multilayered thin films, nanofibres and graphene based composite materials are highlighted in the current research. Multilayer thin films were fabricated by conventional dip coating and newly developed spray coating techniques. Spray coating technique has an advantage of being applied for large scale production as compared to the dip coating technique. Conformal hydrophobic/hydrophilic and superhydrophobic/hydrophilic thermal switchable surfaces were fabricated with multilayer films of poly(allylaminehydrochloride) (PAH) and silica nanoparticles by the dip coating technique, followed by the functionalization with thermosensitive polymer-poly(N-isopropylacrylamide)(PNIPAAM) and perfluorosilane. The thermally switchable superhydrophobic/ hydrophilic polymer patch was integrated in a microfluidic channel to act as a stop valve. At 70 degree centigrade, the valve was superhydrophobic and stopped the water flow (close status) while at room temperature, the patch became hydrophilic, and allowed the flow (open status). Spray-coated multilayered film of poly(allylaminehydrochloride) (PAH) and silica nanoparticles was fabricated on polycarbonate substrate as an anti-reflection (AR) coating. The adhesion between the substrate and the coating was enhanced by treating the polycarbonate surface with aminopropyltrimethoxylsilane (APTS) and sol-gel. The coating was finally made abrasion-resistant with a further sol-gel treatment on top of AR coating, which formed a hard thin scratch-resistant film on the coating. The resultant AR coating could reduce the reflection from 5 to 0.3% on plastic. Besides multilayered films, the fabrication of polyelectrolyte based electrospun nanofibers was also explored. Ultrathin nanofibers comprising 2-weak polyelectrolytes, poly(acrylic acid) (PAA) and poly(allylaminehydrochloride) (PAH) were fabricated using the electrospinning technique and methylene blue (MB) was used as a model drug to evaluate the potential application of the fibers for drug delivery. The release of MB was controlled in a nonbuffered medium by changing the pH of the solution. Temperature controlled release of MB was obtained by depositing temperature sensitive PAA/poly(N-isopropylacrylamide) (PNIPAAM) multilayers onto the fiber surfaces. The sustained release of MB in a phosphate buffered saline (PBS) solution was achieved by constructing perfluorosilane networks on the fiber surfaces as capping layers. The fiber was also loaded with a real life anti-depressant drug (2,3-tertbutyl-4-methoxyphenol) and fiber surface was made superhydrophobic. The drug loaded superhydrophobic nanofiber mat was immersed under water, phosphate buffer saline and surfactant solutions in three separated experiments. The rate of release of durg was monitored from the fiber surface as a result of wetting with different solutions. Time dependent wetting of the superhydrophobic surface and consequently the release of drug was studied with different concentrations of surfactant solutions. The results provided important information about the underwater superhydrophobicity and retention time of drug in the nanofibers. The nanostructured polymers like nanowires, nanoribbons and nanorods had several other applications too, based on their structure. Different self-assembled structures of semiconducting polymers showed improved properties based on their architectures. Poly(3-hexylthiophene) (P3HT) supramolecular structures were fabricated on P3HT-dispersed reduced graphene oxide (RGO) nanosheets. P3HT was used to disperse RGO in hot anisole/N, N-dimethylformamide solvents, and the polymer formed nanowires on RGO surfaces through a RGO induced crystallization process. The Raman spectroscopy confirmed the interaction between P3HT and RGO, which allowed the manipulation of the composite's electrical properties. Such a bottom-up approach provided interesting information about graphene-based composites and inspired to study the interaction between RGO and the molecular semiconductor-tetrasulphonate salt of copper phthalocyanine (TSCuPc) for nanometer-scale electronics. The reduction of graphene oxide in presence of TSCuPc produced a highly stabilized aqueous composite ink with monodispersed graphene sheets. To demonstrate the potential application of the donor (TSCuPc)Â acceptor (graphene) composite, the RGO/TSCuPc suspension was successfully incorporated in a thin film device and the optoelectronic property was measured. The conductivity (dark current) of the composite film decreased compared to that of pure graphene due to the donor molecule incorporation, but the photoconductivity and photoresponsivity increased to an appreciable extent. The property of the composite film overall improved with thermal annealing and optimum loading of TSCuPc molecules.
Ph.D.
Department of Chemistry
Sciences
Chemistry PhD

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18

Yarmolenko, O. V., S. A. Baskakov, Y. M. Shulga, P. I. Vengrus i O. N. Efimov. "Supercapacitors Based on Composite Polyaniline / Reduced Graphene Oxide with Network Nanocomposite Polymer Electrolyte". Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35510.

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The paper describes investigation on new types of supercapacitors based on composite polyani-line/reduced graphene oxide with network nanocomposite polymer electrolyte. Its prototypes are all solid state. The new network polymer electrolytes based on polyethylene glycol diacrylate and nanoparticle SiO2 was synthesized by reaction of radical polymerization in the environment of liquid organic electrolyte. The work is aimed to obtain a polymer electrolyte that is compatible with the electrode materials of superca-pacitors. For these purposes the method of FTIR spectroscopy, a.c. electrochemical impedance and gal-vanostatic cycling were used. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35510

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19

Modarres, Mohammad Hadi. "Reduced graphene oxide nanoparticle hybrids and their assembly for lithium-ion battery anodes". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277144.

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Lithium-ion batteries (LIBs) are an integral part of consumer electronic devices and electric vehicles. There is a growing need for LIBs with higher capacity, rate performance and cycling stability. At the anode electrode these challenges are being addressed for instance by utilising materials with higher theoretical capacity compared to graphite (372 mAh/g) or by optimising the morphology of materials through nanostructuring of the electrode. In this thesis the former is investigated by synthesising a reduced graphene oxide (rGO) tin sulphide (SnS2) hybrid, and the latter by self-assembly of rGO sodium titanate and rGO titanium dioxide (TiO2) nanorods. In Chapter 2, SnS2 is investigated due to its high theoretical capacity as an anode material (645 mAh/g), low cost and environmental benignity. SnS2 nanoparticles were grown directly on rGO sheets which provide a conductive framework and limit the detachment of tin particles which undergo large volume changes during alloying reactions. However, a fast decrease in capacity was observed. Post-mortem analysis of the electrodes showed that rGO becomes irreversibly passivated suggesting that additional measures to retain effective charge transport between the low weight percent conductive additive and the active phase during cycling are required. An alternative material system based on nanorods of intercalation materials (sodium titanate and TiO2) wrapped by rGO sheets was chosen to investigate self-assembly in anodes to address the low packing density of nanomaterials. A drop-casting method was used to align rGO-sodium titanate nanorods through evaporation driven self-assembly (Chapter 3) which relies on a combination of electrostatic repulsive forces originating from the rGO coating, and liquid crystal phase formation at high concentrations, facilitated by the high aspect ratio nanorods. As reference, non-aligned films were prepared by adjusting the pH of the nanorod dispersion. Freestanding aligned and non-aligned films were converted to rGO-TiO2 (Chapter 4). The volumetric capacity of the self-assembled films was double that of non-aligned films, and up to 4.5 times higher than traditional casted electrodes using the same material. Further, up to rates of 4 C, the self-assembled films outperformed the non-aligned films. These films showed no sign of capacity fading up to 1000 cycles, which together with post-mortem analysis confirms that these assembled structures are maintained during battery cycling.

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20

Konkena, Bharathi. "Aqueous Dispersions of Graphene Oxide, Reduced Graphene Oxide and Functionalized Graphene Oxide". Thesis, 2014. http://etd.iisc.ac.in/handle/2005/3035.

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Graphene sheets, one atom thick, two dimensional layers of carbon atoms, have gained enormous importance over the past few years due to their unique attributes - high electronic, thermal conductivities and exceptional mechanical strength. Chemical reduction of graphene oxide (GO) has been considered as a viable route for large scale production of graphene sheets. The reduced graphene oxide (r -GO) sheets although their conductivities are comparatively lower than that of graphene are nevertheless versatile material for applications in thin films and composites. An important consideration in the design of solution processing techniques for the preparation of processable graphene sheets is the dispersibility of GO and r -GO in different solvents, especially aqueous dispersibility. While GO is dispersible in water over a wide range of pH values, r -GO shows poor dispersibility and over a limited range of pH values. Graphene oxide, the oxidized form of graphene, are single atomic layers with lateral dimension that can extend to hundreds of nanometers. The sheets contain a sizable fraction of carbons that are sp3 hybridized and covalently bonded to oxygen in the form of epoxy, carbonyls as well as ionizable hydroxyl and carboxylic functional groups located on the rim of the sheets. The remaining carbons form isolated sp2 graphene like networks. On reduction the oxygen functionalities are removed and the sp2 network partially restored. This thesis focuses on the aqueous dispersibility of GO and r -GO, and describes a strategy to enhance the dispersibility of r -GO by cyclodextrin functionalization. Chapter 1 of the thesis provides a brief review of the synthetic procedures and structure of GO and r -GO while Chapter 2 describes the experimental methods and characterization techniques used in the thesis. The chemistry underlying the aqueous dispersibility of GO and r -GO at different values of pH have been investigated by zeta potential measurements, pH titrations and infrared spectroscopy (Chapter 3). These measurements show that r -GO sheets have ionizable groups with a single pKa value (8.0) while GO sheets have groups that are more acidic (pKa = 4.3), in addition to groups with pKa values of 6.6 and 9.0. Infrared spectroscopy has been used to follow the sequence of ionization events. In both GO and r -GO sheets, it is ionization of the carboxylic groups that is primarily responsible for the build up of charge, but on GO sheets, the presence of phenolic and hydroxyl groups in close proximity to the carboxylic groups lowers the pKa value by stabilizing the carboxylate anion, resulting in superior water dispersibility. Till recently GO was primarily considered only as an easily available precursor for chemical routes to r -GO but it has now been recognized as an interesting material in its own right. Two such attributes that have attracted wide spread attention are the in- trinsic and tunable fluorescence of GO as well as formation of liquid crystalline phases. Aqueous dispersions of GO exhibit strong pH dependent fluorescence in the visible region that originates, in part, from the oxygenated functionalities present. In Chapter 4, the spectral migration on nanosecond timescales of the pH dependent features in the fluores- cence spectra of GO is described. The changes in the steady state fluorescence spectra with pH have been correlated with the sequence of dissociation events that occur in GO dispersions at different values of pH described in Chapter 3, from time resolved emission spectra (TRES) constructed from the wavelength dependent fluorescence decay curves, it is shown that the migration is associated with excited state proton transfer. Both ‘intramolecular’ and ‘intermolecular’ transfers involving the quasimolecular oxygenated aromatic fragments are observed. Aqueous dispersions of GO constitute a distinctive class of 2D-anisotropic colloids with competing interactions - long range electrostatic repulsion, originating from ionized carboxylic groups located on the rim of the sheets and weak dispersive attractive interactions originating from the un-oxidized sp2 graphitic domains. In Chapter 5, it is shown that, colloidal dispersions of GO are intrinsically frustrated, exhibiting a range of arrested or metastable states, encompassing fluid, glass and gels that coexist with liquid crystalline order. These states can be accessed by varying the relative magnitudes of the repulsive and attractive forces by changing the ionic strength of the medium, by addition of salt and/or the concentration of the dispersion. At low salt concentrations, where long range electrostatic repulsions dominates, the formation of a repulsive Wigner glass is observed while at high salt concentrations, when attractive forces dominate, the formation of gels that exhibits a nematic to columnar liquid crystalline transition. These studies highlights how the chemical structure of GO - hydrophilic ionizable groups and hydrophobic graphitic domains coexisting on a single sheet - gives rise to a rich and complex phase diagram. The poor dispersibility of r -GO in aqueous media limits its use in practical applica- tions. To enhance the dispersibility, r -GO sheets have been functionalized by covalently linking -cyclodextrin ( -CD) cavities to the sheets via an amide linkage (Chapter 6). The functionalized -CD: rGO sheets, in contrast to r -GO, are dispersible over a wide range of pH values (2 - 13). Zeta potential measurements indicate that there is more than one factor responsible for the dispersibility. It is shown that planar aromatic molecules adsorbed on the r -GO sheet as well as nonplanar molecules included in the tethered -CD cavities have their fluorescence effectively quenched by the -CD: rGO sheets. The -CD: rGO sheets combine the hydrophobicity associated with r -GO along with the hydrophobicity of the cyclodextrin cavities in a single water dispersible material. Resonance Raman spectroscopy is a powerful analytical tool for detecting and identi- fying analytes, but the associated strong fluorescence background severely limits the use of the technique. In Chapter 7, it is shown that the cyclodextrin functionalized -CD: rGO sheets, described in Chapter 6, provides a versatile platform for resonance Raman detection. Planar aromatic and dye molecules that adsorb on the r -GO graphitic domains and non-planar molecules included within the tethered -CD cavities have their fluorescence effectively quenched. Using the water dispersible -CD: rGO sheets, it is possible to record the resonance Raman spectra of adsorbed and included organic chromophores directly in aqueous media without having to extract or deposit on a substrate. The Raman signal intensities show a linear dependence with the concentration of analyte present in water. This is significant, as it allows for the identification and estimation of organic analytes present in water by resonance Raman spectroscopy.

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21

Konkena, Bharathi. "Aqueous Dispersions of Graphene Oxide, Reduced Graphene Oxide and Functionalized Graphene Oxide". Thesis, 2014. http://hdl.handle.net/2005/3035.

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Graphene sheets, one atom thick, two dimensional layers of carbon atoms, have gained enormous importance over the past few years due to their unique attributes - high electronic, thermal conductivities and exceptional mechanical strength. Chemical reduction of graphene oxide (GO) has been considered as a viable route for large scale production of graphene sheets. The reduced graphene oxide (r -GO) sheets although their conductivities are comparatively lower than that of graphene are nevertheless versatile material for applications in thin films and composites. An important consideration in the design of solution processing techniques for the preparation of processable graphene sheets is the dispersibility of GO and r -GO in different solvents, especially aqueous dispersibility. While GO is dispersible in water over a wide range of pH values, r -GO shows poor dispersibility and over a limited range of pH values. Graphene oxide, the oxidized form of graphene, are single atomic layers with lateral dimension that can extend to hundreds of nanometers. The sheets contain a sizable fraction of carbons that are sp3 hybridized and covalently bonded to oxygen in the form of epoxy, carbonyls as well as ionizable hydroxyl and carboxylic functional groups located on the rim of the sheets. The remaining carbons form isolated sp2 graphene like networks. On reduction the oxygen functionalities are removed and the sp2 network partially restored. This thesis focuses on the aqueous dispersibility of GO and r -GO, and describes a strategy to enhance the dispersibility of r -GO by cyclodextrin functionalization. Chapter 1 of the thesis provides a brief review of the synthetic procedures and structure of GO and r -GO while Chapter 2 describes the experimental methods and characterization techniques used in the thesis. The chemistry underlying the aqueous dispersibility of GO and r -GO at different values of pH have been investigated by zeta potential measurements, pH titrations and infrared spectroscopy (Chapter 3). These measurements show that r -GO sheets have ionizable groups with a single pKa value (8.0) while GO sheets have groups that are more acidic (pKa = 4.3), in addition to groups with pKa values of 6.6 and 9.0. Infrared spectroscopy has been used to follow the sequence of ionization events. In both GO and r -GO sheets, it is ionization of the carboxylic groups that is primarily responsible for the build up of charge, but on GO sheets, the presence of phenolic and hydroxyl groups in close proximity to the carboxylic groups lowers the pKa value by stabilizing the carboxylate anion, resulting in superior water dispersibility. Till recently GO was primarily considered only as an easily available precursor for chemical routes to r -GO but it has now been recognized as an interesting material in its own right. Two such attributes that have attracted wide spread attention are the in- trinsic and tunable fluorescence of GO as well as formation of liquid crystalline phases. Aqueous dispersions of GO exhibit strong pH dependent fluorescence in the visible region that originates, in part, from the oxygenated functionalities present. In Chapter 4, the spectral migration on nanosecond timescales of the pH dependent features in the fluores- cence spectra of GO is described. The changes in the steady state fluorescence spectra with pH have been correlated with the sequence of dissociation events that occur in GO dispersions at different values of pH described in Chapter 3, from time resolved emission spectra (TRES) constructed from the wavelength dependent fluorescence decay curves, it is shown that the migration is associated with excited state proton transfer. Both ‘intramolecular’ and ‘intermolecular’ transfers involving the quasimolecular oxygenated aromatic fragments are observed. Aqueous dispersions of GO constitute a distinctive class of 2D-anisotropic colloids with competing interactions - long range electrostatic repulsion, originating from ionized carboxylic groups located on the rim of the sheets and weak dispersive attractive interactions originating from the un-oxidized sp2 graphitic domains. In Chapter 5, it is shown that, colloidal dispersions of GO are intrinsically frustrated, exhibiting a range of arrested or metastable states, encompassing fluid, glass and gels that coexist with liquid crystalline order. These states can be accessed by varying the relative magnitudes of the repulsive and attractive forces by changing the ionic strength of the medium, by addition of salt and/or the concentration of the dispersion. At low salt concentrations, where long range electrostatic repulsions dominates, the formation of a repulsive Wigner glass is observed while at high salt concentrations, when attractive forces dominate, the formation of gels that exhibits a nematic to columnar liquid crystalline transition. These studies highlights how the chemical structure of GO - hydrophilic ionizable groups and hydrophobic graphitic domains coexisting on a single sheet - gives rise to a rich and complex phase diagram. The poor dispersibility of r -GO in aqueous media limits its use in practical applica- tions. To enhance the dispersibility, r -GO sheets have been functionalized by covalently linking -cyclodextrin ( -CD) cavities to the sheets via an amide linkage (Chapter 6). The functionalized -CD: rGO sheets, in contrast to r -GO, are dispersible over a wide range of pH values (2 - 13). Zeta potential measurements indicate that there is more than one factor responsible for the dispersibility. It is shown that planar aromatic molecules adsorbed on the r -GO sheet as well as nonplanar molecules included in the tethered -CD cavities have their fluorescence effectively quenched by the -CD: rGO sheets. The -CD: rGO sheets combine the hydrophobicity associated with r -GO along with the hydrophobicity of the cyclodextrin cavities in a single water dispersible material. Resonance Raman spectroscopy is a powerful analytical tool for detecting and identi- fying analytes, but the associated strong fluorescence background severely limits the use of the technique. In Chapter 7, it is shown that the cyclodextrin functionalized -CD: rGO sheets, described in Chapter 6, provides a versatile platform for resonance Raman detection. Planar aromatic and dye molecules that adsorb on the r -GO graphitic domains and non-planar molecules included within the tethered -CD cavities have their fluorescence effectively quenched. Using the water dispersible -CD: rGO sheets, it is possible to record the resonance Raman spectra of adsorbed and included organic chromophores directly in aqueous media without having to extract or deposit on a substrate. The Raman signal intensities show a linear dependence with the concentration of analyte present in water. This is significant, as it allows for the identification and estimation of organic analytes present in water by resonance Raman spectroscopy.

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22

Jewell, Ira. "Electrical characterization of thermally reduced graphite oxide". Thesis, 2010. http://hdl.handle.net/1957/16436.

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This thesis describes the transport properties observed in thermally treated graphite oxide (GO), which holds promise as an economical route to obtaining graphene. Graphene is a material consisting of a single atomic plane of carbon atoms and was first isolated as recently as 2004. Several isolation techniques have been investigated, including mechanical exfoliation, chemical vapor deposition, and the reduction (by various methods) of chemically synthesized graphite oxide. Two fundamental questions are pursued in this work. The first is concerned with the maximum electrical conductivity that can be achieved in atomically thin reduced graphite oxide samples (rGO). As produced, GO is insulating and of little use electronically. By heating and exposure to reducing atmospheres, however, the conductivity can be increased. Through the lithographic definition and fabrication of four-point contact structures atop microscopic samples of GO, the resistance of the sample can be monitored in situ as the reduction process takes place. It was discovered that the resistance of few-layer GO could be decreased by an order of magnitude when heated to 200 °C and subsequently cooled back to room temperature in forming gas. Final resistivities were on the order of 0.5 Ω-cm. An ambipolar field effect was observed in the thermally treated samples, with resistance decreasing by up to 16 % under a substrate bias of ±20 V. Mobilites were inferred to be on the order of 0.1 cm²/V-s. It was also found that the presence of forming gas during reduction decreased the resistance of the GO samples by roughly one half. The second question that this work begins to answer is concerned with the distance that electrons can travel in such thermally-reduced GO before spin-randomizing scattering. The answer can be elucidated with the aid of magnetoresistance measurements using ferromagnetic contacts to inject a spin-polarized current through the sample. The observation of the magnetoresistive effect with the contacts separated by a certain distance can be taken as evidence of a spin coherence length in the material of at least that distance. Though this experiment has not yet been carried out, progress has been made toward its possibility; specifically in the fabrication and characterization of independently switchable magnetic contacts. By exploiting magnetic shape anisotropy, contact pairs have been fabricated and demonstrated to differ in magnetic coercivity by up to 8 Oe.
Graduation date: 2011

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23

史博文. "Surfactant Modified Reduced Graphene Oxide Supercapactiors". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/73800505814063503834.

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碩士
國立高雄應用科技大學
模具工程系
105
Reduced graphene oxide can be wrapped with surfactant such as CTAB or SDS to reduce the restack effect between graphene layers and hence increasing the capacitance and energy density of the materials. However, if we can increase the distance between the reduced graphene oxide layers, more ions or larger ions can move in and out the vacancies easier. To achieve this, the reduced graphene oxide was wrapped with ionic surfactant such as CTAB or SDS. The Br anion of the CTAB and the Na cation of the SDS surfactant can be replaced by the larger anion and cation of the ionic liquid EMI-TFSI. Through the ion replacement, the XRD diffraction results indicated an increase on the distance between layers of the graphene. Also both the capacitance and energy density are improved by this surface modification of the reduced graphene oxide. Key words：graphene、ionic surfactant、ionic liquid

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24

Khan, Mustaque Ali. "Efficient Photodetectors Based on Reduced Graphene Oxide". Thesis, 2016. https://etd.iisc.ac.in/handle/2005/4379.

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Chapter 1: In chapter 1, we have presented a brief introduction on photodetector and its various applications. Chapter 2: Chapter 2 is the discussion about experimental methods and characterization tools. In this chapter, we have briefly discussed the experimental methods we have used for preparation of our materials. Then, we have discussed the characterization techniques we have used to characterize our prepared materials. Chapter 3: We have prepared graphene oxide thin film by spin coating. Then, we have reduced it by hydrazine vapour to obtain reduced graphene oxide thin film. We have studied the photodetection properties of reduced graphene oxide thin film. Chapter 4: Recently, there is a surge of preparation methods for reduced graphene oxide. But most of the times, many of its properties are not explored. In this chapter, we have explored infrared photodetection properties of metal reduced graphene oxide. Chapter 5: In chapter 5, we have shown enhanced infrared photodetection by solvothermal reduced graphene oxide. Responsivity values of our photodetectors are comparable with many graphene-based photodetectors. Chapter 6: We have presented our work on highly responsive infrared detector based on reduced graphene oxide in chapter 6. We have studied infrared detection by our photodetectors. We have done experiment to find out the bolometric contribution to the photocurrent. Chapter 7: Ultraviolet photodetection by ZnO-nanosheets-decorated reduced graphene oxide has been studied in this chapter. ZnO-nanosheets film shows very less UV photo response. In case of reduced graphene oxide current value decreases during UV illumination. But, after drop casting ZnO-nanosheets on reduced graphene oxide film significant enhancement in photocurrent has been observed. Chapter 8: This chapter is about summary of research works and future works.

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25

Liou, Hong-Ming, i 劉宏明. "Thermoelectric Transport Measurements of Reduced Graphene Oxide". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/65637432223925865239.

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碩士
國立交通大學
電子物理系所
103
Graphene and reduced graphene oxide device are fabricated using standard electron-beam lithography and thermal evaporation. The device resistance is measured in the temperature range from 200 to 300 K. The result shows that electron transport in reduced graphene oxide can be described by Mott’s two-dimensional variable range hopping. By applying back gate voltage, both graphene and reduced graphene oxide show ambipolar behavior in field effect responses. The sign of thermoelectric power (TEP) of graphene and reduced graphene oxide changes across the charge neutrality point since the majority carriers are changed from electrons to holes. The oxygen coverage of reduced graphene oxide can be estimated from its conductivity. The TEP of reduced graphene oxide increases with increasing oxide coverage.

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26

Li, Ya-Chi, i 李雅琪. "Electron transport in thermally reduced graphene oxide". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/60299391989619357764.

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碩士
國立交通大學
電子物理系所
99
In this study, transport properties of thermally reduced-graphene oxide (r-GO) nanodevices have been investigated. Graphene oxide sheets are made via a modified Hummers’ method and are stocked in de-ionized water. Graphene oxide sheets are then deposited on SiO2 (300 nm)/Si substrates with pre-patterned alignment marks and micrometer scale electrodes. The Si substrate is taken as a back gate electrode. Prior to electron beam lithography process, as-deposited sheets are subjected to annealing at 400℃ for 24 h in order to remove oxygen functional groups and to restore themselves to high conducting graphene. Afterwards, the electron beam lithography is employed to fabricate current leads in conjunction with those r-GO sheets. The separation distance between two current leads is purposely maintained at 1 μm in all r-GO nanodevices for analysis. All electrical measurements are carried out under a 760-Torr helium gas environment at temperature ranging from 300 to 100 K. The r-GO nanodevices reveal the room-temperature (RT) resistances and the mobilities, varying from 10^5 to 10^8 Ω and 10^(-3) to 10^(-1) cm^2/ V*s, respectively. Moreover, electron transport in r-GO nanodevices can be well-described by two-dimensional Mott’s-variable range hopping. According to fitting parameters of the Mott model, we found that the large variation of RT resistance is ascribed to the change of number of localized state at Fermi level in r-GO, rather than that of the localization length. Our investigation provides a pathway to understand the fundamental conduction mechanism in thermally reduced graphene oxide and to engineer for electronic and optical applications in the near future.

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27

Tzu-YangLin i 林子揚. "Preparation and application of iron oxide/ reduced graphene oxide nanocomposites". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/jzz2ce.

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碩士
國立成功大學
化學工程學系
102
This thesis concerns the preparation of iron oxide/reduced grapheme oxide nanocomposites and their applications in adsorption and supercapacitor. For the first part, an arginine-capped nanocomposite of iron oxide nanoparticles and reduced graphene oxide (iron oxide/rGO) has been synthesized as a magnetic nano-adsorbent for the removal of acid dyes AO12 and AG25 via a facile one-step green route with L-arginine as the reducing agent and capping agent. It was quite efficient for the adsorption of acid dyes due to the electrostatic interaction and the van der Waals force or π−π interaction between the acid dyes and the arginine-capped iron oxide/rGO nanocomposite. Moreover, the adsorption for both acid dyes obeyed the Langmuir isotherms. In addition, the adsorption process obeyed the pseudo second-order kinetic model. Also, both acid dyes could be desorbed by NaOH solution and the iron oxide/rGO nanocomposite exhibited good reusability. For the second part, rGO and iron oxide nanoparticles were deposited on the surface of nickel foam (NF) successively via a two-step hydrothermal method to obtain a 3-D iron oxide/rGO/NF composite electrode for supercapacitors. In addition to examine the effect of reaction time for the deposition of rGO on the followed iron oxide deposition and the capacitance, it was also shown that the capacitance of composite electrode was much higher than those of iron oxide/NF and rGO/NF and even their sum. This revealed the iron oxide and rGO of composite electrode exhibited a significant synergistic effect.

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28

Jun-Wang i 王駿. "Study of large-area reduced graphene oxide film". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/9x9sw9.

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碩士
國立臺灣科技大學
機械工程系
103
In recent years, the research and application of graphene becoming more and more popular. This two-dimensional material exhibits amazing properties on the application of all aspects, some scholars even say that graphene will change the way we live. This study used PVD sputtering collocation high-temperature oxidation and high-temperature vacuum treatment to manufacture graphene. After trying different films thickness, oxidative induction time and high-temperature vacuum reducing, then use Raman spectroscopy, Thermogravimetry Analysis(TGA) and Atomic Force Microscope(AFM) to analyze. Finally succeed to manufacture large area of continuously graphene film. In the result, most multiple groups of empirical data could succeed to manufacture grapheme. This empirical data had great achievement after using AFM, TGA and Raman spectroscopy to analyze.

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29

YAN, KE-DUN, i 嚴克敦. "Microwave Absorbing Properties of Reduced Graphene Oxide Papers". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/qwqmjv.

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30

Wang, Guan-Ying, i 王冠穎. "Preparation of Thin Film with Reduced Graphene Oxide". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/f6fc74.

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碩士
逢甲大學
化學工程學系
107
In order to improve the interface situation that might be encountered in producing multi-layer structured device, a method using graphene oxide (GO) undergoes modification, adsorption and chemical reduction of was proposed in this study to prepare electrically conducting graphene thin films. Modified GO is able to enhance the adhesion between adjacent two layers of different materials when it is deposited as an interfacial layer. First we used a large amount of oil-water interface to graft long-chain alkyl groups to one side of GO by amidaion reaction of the -COOH groups (carboxyl group) on GO and the -NH2 groups (amine group) of dodecylamine, resulting in planar GO surfactant (GO-SFT). Second, the -OH groups (hydroxyl groups) out of hydrolysis of the silane coupling agent condensed with other wardly, -OH groups of its kind and with those on the ITO glass. The long-chain alkyl groups of silane making the face out making the surface hydrophobic. Third, the GO-SFT is dissolved in water with the hydrophobic substrate immersed. The hydrophobic ends of the GO-SFT were fused with those on the surface so that the hydrophilic ends of GO-SFT face outwardly. Finally, using aqueous hydrazine solution, the hydrophilic functional groups of GO-SFT were removed, rendering reduced GO (RGO), which enhanced the electrical conductance of the adsorbed layer of graphene conductivity is increased. It was found in previous study that GO-SFT possesses a critical micelle concentration (CMC) in aqueous solution, indicating that it can form micelles in water and change the surface tension. In this study, we successfully adsorbed GO-SFT onto a hydrophobic surface, reduced to RGO, and created a large-area conductive thin film of graphene.

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31

Huang, Jhong-Yi, i 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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32

Alazmi, Amira. "Rational Design of (Reduced) Graphene Oxide Materials and Their Applications". Diss., 2018. http://hdl.handle.net/10754/629892.

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The Graphene term has become synonymous with layered carbon sheets having thicknesses ranging from the monolayer to stacks of about ten layers. For bulk volume production, graphite chemical exfoliation is the preferred solution. For this reason, much interest has congregated around different processes to oxidize and peel off graphite to obtain graphene oxide (GO) and its counterpart, reduced GO (rGO). The community at-large has quickly adopted those processes and has been intensively using the resulting (r)GO as active materials for a myriad of applications. Yet, partially given the absence of comparative studies in synthesis methodologies, a lack of understanding persists on how to best tailor these carbon materials for a given application. In this dissertation, the effect of using different chemical oxidation-reduction strategies for graphite, namely the impact on the structure and chemistry of GOs and rGOs is systematically discussed. Added to this, it is demonstrated that the drying step of the powdered materials cannot be neglected. Its influence is demonstrated in studies such as the optimization of capacitance of rGOs touted as electrochemical energy storage materials (Chapter 4). It is concluded that, in order to maximize the performance of GO and rGO materials for any particular application, there must be a judicious choice of their synthesis steps. Obvious as it may be for anyone working in Chemistry, this point has been surprisingly overlooked for too long by the vast majority of those working with these carbon materials.

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33

Yang, Yu-Jhe, i 楊育哲. "Electrical and Optical Properties of Plasma Reduced Graphene Oxide". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/9454vk.

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碩士
國立中興大學
光電工程研究所
101
In recent years, graphene is a unique two-dimensional structure with good electrical conductivity and thermal conductivity. However graphene oxide has attracted considerable attention because it has tunable surface chemical properties, electrical and optical properties. Many reduction approaches have been developed and most of reduction processes have abundant defects. In study, CH4 plasma treatment could reduce the graphene oxide and help defects repair. So we studied plasma reduction and decreased defects at the same time by the three kinds of the gas plasma such as H2, CH4 and H2+CH4 and compared their electrical and optical properties. Here we used plasma to reduce graphene oxide by PECVD. FTIR and XPS are used to know functional groups of graphene oxide, Raman is used to know molecular structure of graphene oxide and the two analysis methods can be used to know reduction level. In this thesis, we know H2+CH4 plasma treatment to reduce graphene oxide is outstanding, so we studied the relationship of transmittance and energy band gap, electrical properties, and the difference of exposure before and after reduction. We discover reduction level advance with the plasma treatment time increasing, so conductivity is increasing, too. Then, the samples were exposed by different light. Especially exposure to UV light, the measure results prove the current is apparent decreasing at low voltage.

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34

Kai-ChihHsu i 許凱智. "Preparation and applications of nanoparticles-deposited reduced graphene oxide". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/60109120605446246625.

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博士
國立成功大學
化學工程學系
103
Recently, graphene has emerged as a key material or support for the various applications owing to its excellent physical, chemical and electronic properties. As the derivatives of graphene, graphene oxide (GO) and reduced graphene oxide (rGO) are widely used as starting materials for the fabrication of composites due to their low-cost property, large scale production and easy functionalization owing to the many reactive oxygenated functional groups. This dissertation includes four parts: 1. Green synthesis and synergistic catalytic effect of Ag/reduced graphene oxide nanocomposite; 2. Microwave-assisted green synthesis of Ag/reduced graphene oxide nanocomposite as a surface-enhanced Raman scattering substrate with high uniformity; 3. Fabrication of Ag/TiO2/reduced graphene oxide nanocomposite as a reusable surface-enhanced Raman scattering substrate with high sensitivity and uniformity; 4. One-step solvothermal synthesis of TiO2/reduced graphene oxide composite as a visible light photocatalyst. In the first part, a nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the formation of Ag nanoparticles and the reduction of graphene oxide simultaneously with L-arginine as the reducing agent. The resulting Ag/rGO nanocomposite contained about 51 wt% of Ag, and the Ag nanoparticles deposited on the surface of rGO had a mean diameter of 8.6 ± 3.5 nm. Also, the Ag/rGO nanocomposite exhibited excellent catalytic activity and stability toward the reduction of 4-NP to 4-AP with sodium borohydride. The reduction reaction obeyed the pseudo-first-order kinetics. The rate constants increased not only with the increase of temperature and catalyst amount but also with the increase of initial 4-NP concentration, revealing that the support rGO could enhance the catalytic activity via a synergistic effect. A mechanism for the catalytic reduction of 4-NP with NaBH4 by Ag/rGO nanocomposite via both the liquid-phase and solid-phase routes has been suggested. In the second part, Ag/rGO composites are applied as surface-enhanced Raman scattering (SERS) substrates owing to the large surface area and two-dimensional nanosheet structure of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with L-arginine as the reducing agent. By increasing the cycle number of microwave irradiation from 1 and 4 to 8, the mean diameters of Ag nanoparticles deposited on the surface of rGO increased from 10.3 ± 4.6 and 21.4 ± 10.5 to 41.1 ± 12.6 nm. The SERS performance of Ag/rGO nanocomposite was examined using the common Raman reporter molecule 4-aminothiophenol (4-ATP). It was found that the Raman intensity of 4-ATP could be significantly enhanced by increasing the size and content of silver nanoparticles deposited on rGO. Although the Raman intensities of D-band and G-band of rGO were also enhanced simultaneously by the deposited Ag nanoparticles which limited the further improvement of SERS detection sensitivity, the detectable concentration of 4-ATP with Ag/rGO nanocomposite as the SERS substrate still could be lowered to be 10−10 M and the enhancement factor could be increased to 1.27 × 1010. Furthermore, it was also achievable to lower the relative standard deviation (RSD) values of the Raman intensities to below 5%. This revealed that the Ag/rGO nanocomposite obtained in this work could be used as a SERS substrate with high sensitivity and homogeneity. In the third part, to solve the problem we met in the second part, Ag/TiO2/rGO nanocomposite was developed as a more powerful SERS substrate with high sensitivity and uniformity by using TiO2 intermediate layer to diminish the interference from the Raman intensities of D-band and G-band of rGO. The detectable limit of 4-ATP could be further lowered from 10-10 M to 10-14 M. In the meanwhile, the RSD values remained below 10%. This revealed that the strategy using TiO2 intermediate layer to restrain the enhancement effect of Ag nanoparticles on the SERS intensity of rGO is indeed effective. Moreover, by UV irradiation in water, the photocatalytic property of TiO2 could eliminate the Raman signal of 4-ATP efficiently and made this substrate reusable. After reuse for 5 times, the excellent SERS performance of Ag/TiO2/rGO nanocomposite was retained. Accordingly, the Ag/TiO2/rGO nanocomposite developed in this work could be excellent candidates as a reusable SERS substrate with outstanding sensitivity and uniformity. In the fourth part, a composite of titanium dioxide nanoparticles and reduced graphene oxide (TiO2/rGO) have been prepared via a one-step solvothermal process of titanium(IV) butoxide and GO in the mixed solution of ethylene glycol and water. TiO2 nanoparticles could be deposited uniformly on the surface of rGO. The result revealed that TiO2/rGO composites possessed enhanced photocatalytic activities than pure TiO2 nanoparticles. The incorporation of rGO not only could extend the absorption to the visible light region and narrow the band gap of TiO2 nanoparticles, but also could facilitate the electron transfer from TiO2 nanoparticles to rGO and lead to the separation of the photogenerated electron-hole pairs. Hence, the resulting TiO2/rGO composites exhibited enhanced photocatalytic performance and were expected to be useful in the treatment of organic pollutants.

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35

Chen, Yu-Ting, i 陳昱廷. "Reduced techniques of graphene oxide developed using electric energy". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/06682423200188332549.

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碩士
國立臺灣師範大學
機電工程學系
104
In this study, we present a novel method that uses electric energy to turn graphene oxide into reduced grpahene oxide. The electric energy which contains the arc discharge and atmospheric plasma two methods, both methods have an advantage of rapid heating, high energy and other characteristics. It is suitable for reduce graphene oxide. First, we used the present study Improved Hummers method for preparing graphene oxide. the graphene oxide prepared ID ratio IG is 0.77, carbon to oxygen ratio is 0.232, and the resistance is 280 MΩ. Moreover, the homemade of graphene oxide was prepared for powders, dispersions and film form, respectively. Then the arc discharge and plasma were conducted to experiments. Finally, it will used Raman, electrical resistance, specific surface area and XPS analysis to estimate its characteristics. In the end, it will be compared with reduction effect which is using UV laser to reduce. This study has faced some critical problems during arc discharge experiments. Due to the performance restrictions of instrument can’t be improved. So the resulting of reduction isn’t very effective. Hence, the experiment will focus to the plasma experiments. Through the atmospheric plasma system, it is successfully restored graphene oxide, graphene oxide film under two hours processes time in the case, the resistance value decreased from 280 MΩ to 1657 Ω. The electrically improved significantly, the I2D ratio IG increase from 0 to 0.05. Besides, quartz glass as shelter has used in the reducing experiment, because the integrity of the film is significantly improved. The resistance value decreased from 1657 Ω to 141 Ω. I2D ratio IG increased to 0.3, the reduction of the effect is very good. Experimental results show that electrical properties of reduced graphene oxide is better than GO after plasma treatment, has indeed proved it contains reduction effect. If we combined quartz glass as a shelter with plasma experiment, it will more significantly improve its electrical properties.

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36

Wang, Shu-Wei, i 王書瑋. "Transport in chemically reduced graphene oxide and GaP1-xSbx". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/55462361971208580243.

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碩士
國立臺灣大學
物理研究所
99
This thesis is focused on the electronic properties and the transport mechanism of carriers in nanostructures. It consists of the following two parts: 1. The transport in chemically reduced graphene oxide (rGO): The first part of this study was focused on the transport behavior of carriers in rGO films over a temperature (T) range between 4.5 K and 296 K. Both variable range hopping (VRH) and thermally-activated transports were reported in previous studies. An Arrhenius-type electron transport behavior rather than a VRH one is discovered from our rGO samples almost fully-reduced by the chemical and thermal processes. The resistance (R) dependence on the thickness of rGO layers, i.e. on the number of the graphene oxide layers, was also investigated. A parallel resistance configuration was suggested to explain the observed R dependence on the film thickness. Furthermore, the comparison of the R-T features from three rGO samples with different thicknesses was conducted. The possible causes giving rise to the R-T characteristics may be ascribed to the electron-electron and electron-phonon interactions existing between the interlayers and at the interface between the rGO film and the SiO2/Si substrate. The unique ambipolar characteristic from a pristine graphene was also observed on our rGO films subject to a small gate voltage (Vg) between -0.3 V and 0.3 V under vacuum. A shift of the charge neutrality point to a positive gate voltage in the resistance-gate-voltage (R-Vg) relation indicated the existence of the charged impurities in the rGO films. 2. The transport in gallium phosphide antimonide (GaP1-xSbx): The second part of this thesis was the study of the electronic and transport properties of the III-V-based alloy GaP0.71Sb0.29 . The analysis of the R-T data below 49 K indicated the transport mechanism was dominated by hopping conduction. When the temperature increased to above 49 K, the thermal energy is high enough to activate the localized carriers, leading to a thermal-activation-dominant transport behavior. The relation between carrier concentration (n) and temperature also pointed to the same result as the analysis of the R-T data. The carrier concentration increased with the decreasing temperature below 50 K, revealing the feature of the hopping transport regime. However, the temperature independence of n beyond 50 K probably indicated a transition to the thermally-activated transport regime.

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37

Hsu, Chia-Wen, i 許嘉紋. "Boron doped reduced graphene oxide for capacitive deionization application". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/ptrnbk.

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碩士
國立交通大學
環境工程系所
106
In present, the shortage of clean freshwater and pollution had poses a critical issue to human habitat on this planet. Here in, capacitive deionization (CDI), an electrochemical water treatment technology has been implemented with the purpose to remove the inorganic ions from the water. CDI holds the promise not only available for ion removal but also consuming low energy consumption, easy operation and act as renewable electrodes. In this study, boron-doped reduced graphene oxide (B-rGO) was synthesized from microwave-assisted hydrothermal method and been selected as an electrode in removing the charge ions from the water through CDI technology. The amount of boron used during the doping process was studied together with the electrochemical cyclic voltammetry and batch type electro-adsorption experiments. The adsorption behavior of B-rGO under different ion concentrations, operating voltages and adsorption capacity of different cations (Na+、Ca2+、Fe3+ and Cu2+) in a single and competitive environment was examined. The results indicated that 30 wt% of B-rGO that synthesized at 170 ºC provide the highest capacitance value up to 356 F/g at 5 mV/s scanning rate. Besides, sodium ion removal has been optimized for 45.9 % when the applied voltage is 1.2 V at concentration of 100 mg/L. The specific electrosorption capacity (SEC) of the B-rGO is 2695 µmol/g, which is 12.5 times higher than reduced graphene oxide. In addition, the electro-adsorption efficiency of the cation removal for Ca2+、Fe3+ and Cu2+ at fixed concentration 50 mg/L and voltage 1.2 V is 785 µmol/g, 871 µmol/g and 940 µmol/g, respectively. With all of the reported results, it is proven that the boron atom that doped onto the graphene sheets not only enhance the conductivity of the materials, but also improve the rate of the electron transfer and in directly enhance the efficiency of charge ions removal.

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38

Wu, Yi-Zhen, i 吳翊甄. "NiO-Reduced Graphene Oxide-ZnO composite nanostructures for photodetectors". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/f9p7p2.

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碩士
國立臺灣科技大學
電子工程系
107
In this study, we report UV photodetectors (PDs) based on the combination of ZnO nanorods (ZNR), reduced graphene oxide (rGO) and nickel oxide (NiO) via a simple solution process. More briefly, we divide this study into four parts. The first part is about ZNR growth using different seed layer spin speed based UV PDs. The second part comprises the UV PDs based on rGO-ZNR with different seed layer spin speed and the third part explains UV PDs based on NiO-ZNR with different seed layer spin speed. The fourth part describes the UV PDs with the combinations of NiO-rGO-ZNR. From the overall studies, it was revealed that the as-prepared NiO-rGO-ZNR based PDs exhibit highly enhanced switch (IPhoto/IDark) ratio of 31,116.6 compared to those of NiO-ZNR (5776.02), rGO-ZNR (1880.73) and ZNR (517.95) based PDs. In addition, photo-responsivity (R), quantum efficiency (Q.E) and UV/Visible rejection ratio were also calculated using the responsivity vs wavelength curves. Obviously, the NiO-rGO-ZNR PDs shows the enhanced R (0.072 A/W), Q.E (24.38 %) and UV/Vis rejection ratio (4.49) compared to those of other PDs.

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39

Tsai, I.-Chen, i 蔡宜真. "Environmental applications of 3D reduced graphene oxide modified electrodes". Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5087032%22.&searchmode=basic.

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碩士
國立中興大學
環境工程學系所
107
With the growing usage, antibiotics have been found in the recipient environment and been listed as potential emerging contaminants. Sulfamethoxazole, a representative sulfonamide antibiotic, is one of the most commonly used antibiotics. The increase in the release and accumulation of the unconsumed antibiotics in the effluents and aquatic environment necessitates the development of real-time and in-situ determination technique. In the present work, gold/graphene-based modified electrodes, which showed high selectivity, high sensitivity, and high stability, were found to be promising sensors for determination of sulfamethoxazole in aqueous systems. Additionally, being a predominant class of energy source in the world, fossil fuel is not only a major contributor to climate change but also faces a threat of depletion in the immediate future. Therefore, more and more scientific works have been committed to searching for clean and renewable energy alternatives. Hydrogen is one of the cleanest fuel and renewable green energy and has been hailed as a potential replacement for fossil fuels in the future. In particular, electrochemical hydrogen evolution reaction (HER) has attracted growing attention. In this study, we employ a facile hydrothermal method to synthesize a hybrid structure of MoS2 and reduced graphite oxide (rGO) with a three-dimensional morphology. The three-dimensional structure provides abundant active edge sites and long-term stability. With effective prevention of restacking of MoS2 nanosheets and efficient diffusion of electrolytes through the inside channels, MoS2/rGO hybrid possesses promising catalytic performance for HER.

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40

Yang, Zhen Yue, i 楊鎮岳. "Hydrothermal Synthesis of Reduced Graphene Oxide/Nickel Oxide Composite in Supercapacitor Applications". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8gk9mn.

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碩士
國立臺北科技大學
資源工程研究所
105
Due to the large specific surface area, high conductivity and good chemical stability, Reduced Graphene Oxide(rGO) has been widely applied in various fields. NiO material has similar characteristics with RuO2. Due to the low price, NiO can be produced in large-scale production. Recently, the NiO capacitor has found practical application in life. In this study, the linear NiO/rGO is synthesized by hydrothermal method to form an anode material with superior properties. There are three parts in the thesis: (1) the effect of preparation parameters on the structure and morphology of oxidized graphene and NiC2O4 Precursor, (2) the effects of amount of GO and Ni(NO3)2 on rGO/NiO Composites, (3) the application of rGO / NiO electrode. In this study, rGO / NiO composite is prepared by hydrothermal method with NiC2O4 as precursor. PEG is used as a molecular template to ensure the formation of NiO with a linear morphology. The average length and average width of NiO in the rGO/NiO composite were observed by SEM. The crystal phase of rGO/NiO composites was observed by XRD. FTIR observed effect of reduction on rGO formation. The electric performance of rGO/NiO composites is investigated by cyclic voltammetry. The experimental results indicate that linear NiO can improve the capacitance of rGO / NiO composite. With initial concentration of Ni(NO3)2 of 0.418M, calcination temperature of 300 ℃, the rGO / NiO composite material can have good stability, and charge and charge-discharge efficiency. The specific capacitance value can reach 177.7F/g

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41

Lee, Iping, i 李依平. "NO2 Gas Sensor Based on Polymer-exfoliated Graphene Nanoplatelets and Reduced Graphene Oxide". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3q79e9.

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42

Lin, Jia-Hui, i 林嘉暉. "Synthesis and characterization of Iron Oxide (IO)/FePt/ reduced graphene oxide (rGO) nanocomposites". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/5a8nw9.

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碩士
國立臺北科技大學
製造科技研究所
104
In this study, FePt/reduced graphene oxide (rGO) nanocomposies have been synthesized using a chemical reduction. Triethylene glycol (TEG) as both solvent and reductant, whereas graphene oxide (GO) nanosheets as a supported of FePt nanoparticles. And the precursor of Iron Oxide (IO) have been added at different times in to the synthesis of FePt/rGO nanocomposite to prepared the different structures of Iron Oxide/FePt/rGO nanocomposites. The microstructure, composition, surface morphology and magnetic property of this nanocomposites are methodically characterized by XRD, FI-IR, Raman spectrum, SEM, VSM, high-frequency heater, potentiostat and 808nm infrared diode laser. The above analysis result, it can be observed that the different peaks of rGO, IO and FePt in the XRD pattern. Raman spectroscopy can be observed the peaks of IO between 200 to 800 cm-1 and checking the phase of IO, and the main feature G and D band of rGO that between 1000 to 2000 cm-1. From the FT-IR spectrum, Fe-O, -OH, C-H, C-O and C=C were observed respectively. The saturation magnetization (Ms) of IO/FePt/rGO nanocomposites have been increased through the addition of iron oxide. Observing the properties of the sample through high-frequency heater. In the electrochemical analysis result that adding iron oxide could reduce the CO poisoning effect. Finally, the sample at the wavelength of 808 nm infrared laser have excellent property of photothermal therapy.

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43

Chang, Yun-tsung, i 張允聰. "Electrochemical Supercapacitor Behaviors of Nano Iron Oxide/Polyaniline/Reduced Graphene Oxide Hybrid Materials". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/46456457907088600812.

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碩士
大同大學
材料工程學系(所)
103
Integrated supercapacitors with extended operation voltage are important for high energy density storage devices. Supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. If we integrate the two kinds of supercapacitors, it will enhance the properties of supercapacitors. In this study, we coating the polyaniline on the reduced graphene oxide, and coating the iron oxide on the hybrid, then it will has the best performance. We synthesis the properties of the hybrid supercapacitors ( XRD、SEM、TEM、TGA、FTIR、ICP) and electrochemical analysis. The electrochemical test show that 50wt%PANI/RGO has the best electrochemical performance and has the specific capacitance of 268 F/g. in cycles test, it can be attributed to that too much PANI or too less PANI has not evident offer specific capacitance for RGO. The specific capacitance of 50wt%PANI/RGO is better than that of RGO (165 F/g) or PANI (131 F/g). In Fe3O4/RGO system, 10wt%Fe3O4/RGO has best specific capacitance 240 F/g in 10 cycles test. The result is better than that RGO (165 F/g) or Fe3O4 (4.4 F/g).This study show good performance for the future development of integrated energy storage devices.

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44

Tang, Fa-Shih, i 湯發時. "Synthesis and characterization of In2O3 nanowires/reduced graphene oxide heterostructures". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/b3m447.

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碩士
國立東華大學
材料科學與工程學系
105
A vapor transport process was used to grow indium oxide nanowires on gold catalyzed graphene oxide surfaces by vapor-liquid-solid (VLS) mechanism and graphene oxide surfaces by vapor-solid (VS) mechanism, respectively. The samples were characterized by various characterization techniques and their growth mechanism were discussed. Both X-ray diffraction (XRD) and transmission electron microscopy (TEM) results show that the as-grown indium oxide nanowires are face centered cubic FCC with [100] growth direction. The graphene oxide was reduced to reduced graphene oxide during growth. The FE-SEM images show a high density of nanowires on graphene oxide surface grown by VLS mechanism. Moreover, the In2O3 nanowires were found to preferential grown on thin layers of graphene oxide. The two dimensional growth of In2O3 films were observed on thick layers of graphene oxide. The samples show a higher visible light absorption possible due to the reduced graphene oxide of heterostructures confirmed by UV/Vis absorption spectra. Compared to graphene oxide, the reduced graphene oxide shows a higher luminescence property. On the contrary, the In2O3/rGO heterostures shows weaker luminescence properties due to quenching effect. For visible light photocatalytic applications, the In2O3/rGO heterostructures show a higher visible-light-driven photocatalytic activity owing to the increased photo-induced charge separation efficiency, further increase the formation of superoxide radicals and hydroxyl radicals.

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45

Wong, Jing-ya, i 翁靖雅. "Applications of nitrogen-doped reduced graphene oxide on electrochemical capacitor". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/06898999496283423889.

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碩士
國立臺灣科技大學
化學工程系
102
This study explores the capacity of nitrogen doped reduced graphene oxide (N-doped rGO) in the asymmetric electrolyte [EMI][TFSI]. We employ the Staudenmaier method to exfoliate and reduce the graphene oxide, and find the sample of N-doped rGO owns a surface area, higher than 1100?aC undoped rGO. Hence, the capacitor investigation focuses on how to make most of the electrochemical window of [EMI][TFSI] with N-doped rGO. The electrochemical window of [EMI][TFSI] is measured between -1.65 and +2.6 V (vs. RHE) with platinum electrodes. Another window rarely mentioned in the literature is the intercalation window, which is -1.6 V the lower window limit and +1.2 V (vs. RHE) the upper window limit for N-doped rGO. If we charge/discharge the capacitor in the working window of 2.0 V, the positive and negative potentials vary within the intercalation window. Consequently, the electrode capacitance ratio of positive and negative electrode is near the ratio measured with cyclic voltammetry, assuming energy storage depends on double layer capacitance entirely. When we impose the 3.8 V working window without considering a proper mass balance, we often found the negative electrode exceeds -1.65 V and decomposes the electrolyte. Careful analysis of the electrode potential variations indicates the main restriction is on the negative potential, therefore, the mass ratio of positive over negative (M+/M-) ought to be less than 1 to use the lopsided potential window sufficiently. The capacitor performance of an M+/M- ratio 0.736 is investigated with details.

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46

Li, Jin-An, i 李晉安. "Synthesis and Characterization of Au-Pd/Reduced Graphene Oxide Electrocatalysts". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/54396454619749949834.

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碩士
大同大學
材料工程學系(所)
103
In a direct formic acid fuel cell system, the carbon monoxide produced during the oxidation of formic acid will adsorb on the surface of palladium catalyst and poisoning palladium, also formic acid may leaching and dissolving palladium, leads to decrease the electro-catalytic activity. Previous studies indicated the nano-gold-palladium solid solution can inhibit CO poisoning and prevent the leaching of palladium that may increase electrocatalytic activity and lifetime. This study compared two different methods to reduce gold-palladium alloy on reduced graphene oxide. Two methods are included using reducing agent of sodium borohydride and photoreduction by X-ray irradiation. These two methods can easy to synthesize at room temperature. The gold-palladium nanoparticles are homogeneously deposited on the surface of reduced graphene oxide (RGO). The physical, chemical and electrochemical properties are applied to examine these samples. In this study, FT-IR and XRD are used for functional group and structural analysis, TGA and ICP for compositional measuremnet, the FE-SEM for observing the surface morphology of samples. Cyclic voltammetry (CV) and I-t test are used to evaluate the electrochemical properties of these catalysts. The results of FE-SEM images indicate the diameters of Au-Pd nanoparticles are about 7-9nm and it uniformly disperse on the graphene oxide. However, the results of EDS analysis indicate its composition is not closed to original design. ICP-OES analysis is confirmed EDS results. In electrochemical analysis of Au-Pd electrocatalysts, AuPd/RGO-01A has the better electro-oxidizing current density. Also, its current stability is excellent up to 20 cycles of experiment. Chronoamperometry analysis (CA) results show AuPd/RGO-01A one has the higher response and life time than that of AuPd/RGO-NaBH4. But the stability and life time of these samples are not good enough for practical applications.

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47

Ya-ChiKo i 柯雅淇. "Preparation and application of Ag/ZnO/reduced graphene oxide nanocomposite". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/03458305987687493846.

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碩士
國立成功大學
化學工程學系
103
In this study, Ag/ZnO/reduced graphene oxide (Ag/ZnO/rGO) nanocomposite was fabricated and its applications in the detection and killing of bacteria were investigated. This nanocomposite combined the photocatalytic property of ZnO nanoparticles, the high specific surface area and near infrared (NIR) photothermal conversion property of rGO, and the bacteria-killing capability and surface enhanced Raman scattering (SERS) property of Ag nanoparticles. At first, ZnO/rGO nanocomposite was prepared from zinc acetate and graphene oxide (GO) by solvothermal method in the mixture of ethylene glycol and NaOH aqueous solution. The influences of GO content on the growth of ZnO nanoparticles on the surface of rGO and the photocatalytic property were examined to obtain a ZnO/rGO nanocomposite with better photocatalytic activity. Secondly, in the silver nitrate-containing arginine solution, Ag nanoparticles were deposited on the surface of ZnO/rGO nanocomposite by microwave-assisted method. It was demonstrated that the resulting Ag/ZnO/rGO nanocomposite not only could be successfully used as the SERS substrate for the detection of E-Coli, but also could be used for the efficient killing of E-Coli in the dark and under the full Xe lamp or NIR irradiation via the Ag nanoparticles-related and photocatalytic or photothermal killing mechanisms. The full Xe lamp irradiation led to the best bacteria-killing efficiency and the second best one was observed under NIR irradiation. This revealed that the Ag/ZnO/rGO nanocomposite could provide more ways and better performance for killing bacteria as compared to the individual Ag nanoparticles. Accordingly, the Ag/ZnO/rGO nanocomposite developed in this study indeed possessed both the bacteria detection and killing properties.

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48

Tsao, Rui-Wen, i 曹瑞文. "Investigation of Electron-Hole Pair Production in Reduced Graphene Oxide". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/56351981826981931049.

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碩士
國立交通大學
電子物理系所
102
This experiment use reduced graphene oxide (RGO) to explore transport mechanism and use two probe measurements to measure electrical properties. The oxygen coverage of RGO could be estimated by the conductivity at room temperature. In this experiment, RGO oxygen coverage ratio is about 16%～18%. According to previous work, RGO is well described by 2D VRH in low electric field. This experiment try to study transport properties in high electric field. At 80 K, the J-E curve of RGO cannot be well described by Shklovskii expression since Shklovskii expression is derived at T = 0 K. After considering the temperature factor, the J-E curve of RGO can be fitted well. However, the J-E curve at 300 K did not follow the same model prediction. In this work, we found that the J-E curves make a transition from linear to nonlinear, power law dependences. We also determined the critical field (E_C) for the transition to be E_C≈〖10〗^6 (V/m). According to Schwinger mechanism, the electron-hole pairs is produced near the charge neutrality point. From to a series experiments and analysis, we explored the electric field behavior and compared experiments with the theoretical model. The electric field behavior shows a power law dependence that is in agreement with the theoretical prediction given by J. Schwinger.

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49

Lin, Hung-En, i 林弘恩. "Magnetotransport in chemically reduced graphene oxide and gallium phosphide antimonide". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/99089623646355400100.

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碩士
國立臺灣大學
物理研究所
99
In this thesis, two materials, chemically reduced graphene oxide and GaPSb, were investigated for their magnetotransport behaviors under the influence of a magnetic fields up to 11.6 T at the temperatures between 4.5 K and 80 K. A brief summary of our discovery will be given in the following sections. 1. Magnetotransport in chemically reduced graphene oxide In recent years, transport behavior in chemically reduced graphene oxide (R-GO) has been widely investigated. However similar research in the presence of a magnetic field was rare. In chapter 4, the transport behavior in fully R-GO samples with a magnetic field up to 4 T at selected temperatures between 4.5 K and 80 K was studied. Negative magnetoresistance (NMR) was observed in all our R-GO samples. The magnitude of NMR was found to decrease with the increasing temperature and the increasing thickness of the R-GO film. A Mott hopping behavior, concluded from the data analyzed by using Sivan, Entin-Wohlman, and Imry (SE-WI) model, was found to be the dominant electron conducting mechanism for the NMR phenomenon. The magnetotransport features can be explained by a model based on the spin-coupling effect from vacancy-induced midgap states that facilitate the Mott variable range hopping (VRH) conduction in the presence of an external magnetic field. The origin of the staircase-like NMR revealed on the 3-nm-thick sample is not clear although it was also observed at a lower temperature from the dilute fluorinated graphene. Further investigations are required to elucidate the nature of this unusual behavior. 2. Magnetotransport in gallium phosphide antimonide The second part of this thesis was dedicated to the study of the transport behavior in a GaPSb sample in the presence of a perpendicular magnetic field at low temperatures. The Hall measurement indicated that the carrier concentration was about 1016 cm-3 and electrons were the dominant carriers in our sample. The NMR followed by PMR was observed along with the increase of a magnetic field up to 11.6 T. At the temperature regime between 40 K and 80 K, either three- or two-dimensional Mott VRH model or ES VRH model can be used to describe the electron transport behavior. To elucidate the ambiguity, the magnetoresistance theory in VRH regime was employed to analyze the transport behavior, showing that the transport behavior of the 720-nm-thick GaPSb is consistent with a two-dimensional Mott VRH conductance.

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50

Lee, Chun-Yuan, i 李浚源. "Properties of graphene thin films derived from high temperature reduced graphene oxide/polyethylene glycol". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/39346699920515877541.

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碩士
中原大學
化學研究所
100
Graphene with fast electron mobility, high mechanical strength, high conductivity and transparent characteristics, therefore, becomes very wide applications in electronic components. In this study, graphene was reduced from graphene oxide (GO) by using Hummer’s methods. By adding commercially available polyethylene glycol (PEG) with molecular weight 600, 6000, 20000, and 35000 for slurry formation, we developed the graphene films on glass substrate with good conductivity for electrode applications. The characteristics of graphene/PEG films were studied by using SEM, UV-vis, four proble point conductivity measurement, Raman spectroscopy, and AFM. It was found that PEG with molecular weight around 600~6000 is a better choice for the formation of graphene film on glass substrate in term of conductivity and their trasparancy.

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