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Artykuły w czasopismach na temat "Graphene Nanostructure - Photophysical Properties"
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Ardoña, Herdeline Ann M., Kalpana Besar, Matteo Togninalli, Howard E. Katz i John D. Tovar. "Sequence-dependent mechanical, photophysical and electrical properties of pi-conjugated peptide hydrogelators". Journal of Materials Chemistry C 3, nr 25 (2015): 6505–14. http://dx.doi.org/10.1039/c5tc00100e.
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Reznik, Ivan, Andrey Zlatov, Mikhail Baranov, Roman Zakoldaev, Andrey Veniaminov, Stanislav Moshkalev i Anna Orlova. "Photophysical Properties of Multilayer Graphene–Quantum Dots Hybrid Structures". Nanomaterials 10, nr 4 (9.04.2020): 714. http://dx.doi.org/10.3390/nano10040714.
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Photoelectrical and photoluminescent properties of multilayer graphene (MLG)–quantum dots (QD) hybrid structures have been studied. It has been shown that the average rate of transfer from QDs to the MLG can be estimated via photoinduced processes on the QDs’ surfaces. A monolayer of CdSe QDs can double the photoresponse amplitude of multilayer graphene, without influencing its characteristic photoresponse time. It has been found that efficient charge or energy transfer from QDs to MLG with a rate higher than 3 × 108 s−1 strongly inhibits photoinduced processes on the QD surfaces and provides photostability for QD-based structures.
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Zhang, Fan, Ruilin Man, Zhiyuan Peng i Zhibo Liu. "Synthesis, Characterization and Photophysical Properties of Graphene-Phthalocyanine Hybrid". Asian Journal of Chemistry 26, nr 15 (2014): 4819–26. http://dx.doi.org/10.14233/ajchem.2014.16241.
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Joseph, J., i Y. C. Lu. "Effect of graphene layer thickness on effective modulus of 3D CNT/Graphene nanostructures". International Journal of Computational Materials Science and Engineering 04, nr 02 (czerwiec 2015): 1550010. http://dx.doi.org/10.1142/s2047684115500104.
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Three-dimensional CNT/Graphene nanostructure is consisted of vertically aligned carbon nanotube pillars grown directly on parallel graphene layers. The effect of graphene layer thickness on mechanical properties of the 3D nanostructure is analyzed. Overall, when the graphene layers experience the out-of-plane loading, the effective properties (Young's modulus, shear modulus, and major Poisson's ratio) of the 3D CNT/Graphene structure are significantly dependent upon the thickness of graphene layers. When the graphene layers experience the in-plane loading, the effective properties of the 3D CNT/Graphene structure depend upon the graphene thickness initially and then remain relatively unchanged as the thickness increases. It is found that the optimal performance of the 3D CNT/Graphene structure requires a minimum of thickness for the graphene layers, g/t > 5.
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Zeng, B., Z. G. Li i W. J. Zeng. "N-doped graphene-cadmium sulfide nanoplates and their improved photocatalytic performance". Digest Journal of Nanomaterials and Biostructures 16, nr 2 (2021): 627–33. http://dx.doi.org/10.15251/djnb.2021.162.627.
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Cadmium sulfide nanoplates and N-doped graphene composites (CdS NP/NG) were synthesized for use as photocatalysts. Photocatalytic testing showed that both the two dimensional (2D) nanostructure and nitrogen-doping of graphene contributed to its excellent photocatalytic performance. Here, the 2D nanostructure provided a large number of active sites and the nitrogen-doping of graphene could improve its electronic properties. This work offers a new insight for obtaining a highly efficient CdS/graphene photocatalyst.
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Wibmer, Leonie, Leandro M. O. Lourenço, Alexandra Roth, Georgios Katsukis, Maria G. P. M. S. Neves, José A. S. Cavaleiro, João P. C. Tomé, Tomás Torres i Dirk M. Guldi. "Decorating graphene nanosheets with electron accepting pyridyl-phthalocyanines". Nanoscale 7, nr 13 (2015): 5674–82. http://dx.doi.org/10.1039/c4nr05719h.
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Kim, Jinsang. "Assemblies of conjugated polymers: Intermolecular and intramolecular effects on the photophysical properties of conjugated polymers". Pure and Applied Chemistry 74, nr 11 (1.01.2002): 2031–44. http://dx.doi.org/10.1351/pac200274112031.
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Conjugated polymers are emerging materials for electronic applications due to the tunability of their properties through variation of their chemical structure. Their applications, which currently include light-emitting diodes (LEDs), field effect transistors (FETs), plastic lasers, batteries, and sensors, are expanding to many new areas. The two critical parameters that determine the function of conjugated polymer-based devices are chemical structure and nanostructure of a conjugated polymer in the solid state. While the physical properties of isolated polymers are primarily controlled by their chemical structure, these properties are drastically altered in the solid state due to electronic coupling between polymer chains as determined by their interpolymer packing and conformation. However, the development of effective and precise methods for controlling the nanostructure of polymers in the solid state has been limited because polymers often fail to assemble into organized structures due to their amorphous character and large molecular weight.In this review, recent developments of organizing methods of conjugated polymers and the conformation and interpolymer interaction effects on the photophysical properties of conjugated polymers are summarized.
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Ozcan, Sefika, Sesha Vempati, Ali Çırpan i Tamer Uyar. "Associative behaviour and effect of functional groups on the fluorescence of graphene oxide". Physical Chemistry Chemical Physics 20, nr 11 (2018): 7559–69. http://dx.doi.org/10.1039/c7cp08334c.
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We juxtaposed structural, vibrational and emission properties of graphene oxide with and without a model dispersant. This unveiled a strong associative behavior between graphene oxide sheets and the effect of H-bonds on the photophysical properties.
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Debgupta, Joyashish, Sadananda Mandal, Hemen Kalita, Mohammed Aslam, Amitava Patra i Vijayamohanan Pillai. "Photophysical and photoconductivity properties of thiol-functionalized graphene–CdSe QD composites". RSC Advances 4, nr 27 (2014): 13788. http://dx.doi.org/10.1039/c3ra47420h.
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Fernandes, Flaviano Williams, Vitor Fernando Gigante de Paiva i Gilmar Patrocínio Thim. "Energetic and electronic properties in a multilayered ZnO graphene-like nanostructure". Materials Research 19, nr 3 (28.03.2016): 497–504. http://dx.doi.org/10.1590/1980-5373-mr-2015-0432.
Pełny tekst źródłaRozprawy doktorskie na temat "Graphene Nanostructure - Photophysical Properties"
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CURCIO, DAVIDE. "Growth and Properties of Graphene-Based Materials". Doctoral thesis, Università degli Studi di Trieste, 2017. http://hdl.handle.net/11368/2908114.
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In this thesis, I have focused on graphene-based nanostructures as a versatile means of manipulating the electronic properties of graphene, while working with objects perfect at the atomic level. This is the nanotechnological approach, where we exploit the infinite possibilities of making small things with new materials. For these reasons, I concentrated my research efforts to graphene-based nanomaterials, because graphene is one of the most exciting materials we have to date, and because manipulation of surfaces at the nano-level is what allows us to make new materials today. In this thesis, I will show how we have created and studied new graphene-based nanostructures by employing cutting-edge surface science techniques. Most of the experimental data we have acquired has been given a new light by powerful Density Functional Theory calculations, that allow for an approach where hardly accessible data (experimentally) becomes indirectly known through numerical calculations, while providing valuable feedback for further aimed calculations. I will show how we have undertaken a route that takes us from a detailed study of how carbon monomers, the building blocks of graphene, come to exist on an Ir(1 1 1) surface after ethylene dissociation. Next, simple nanostructures have been ex- ploited, so that the properties of a preexisting graphene layer are manipulated by intercalating different metals between graphene and the substrate. Then I will discuss an experiment where graphene was grown on a highly anisotropic substrate, Ru(1 0 1 0), which proved to be an extremely rich system, giving rise to several self-assembled graphene nanostructures, including nanoribbons and one-dimensional quasi free-standing graphene waves. Then, we will progress to what are commonly perceived as being proper graphene-based nanostructures. We have, in fact, managed to create size selected graphene nanodomes on Ir(1 1 1) using coronene as a precursor, and we have understood many details of the dynamics in the formation of these carbon-based nanostructures, discovering that in certain steps of the reaction they lift from the surface and rotate, before settling in the definitive adsorption position. Furthermore, while performing similar experiments on pentacene (a semiconducting molecule, used the fabrication of molecular FETs) on Ir(1 1 1), we have discovered that the molecules exhibit a reversible dehydrogenation, allowing for a switch between semiconducting molecules and minimalistic graphene nanoribbons, only one aromatic ring wide.
Finally, a size-selected nanocluster source system will be described. In parallel with my research activity, I have been profoundly involved in the commissioning of such a machine that is currently capable of producing size selected nanoclusters.
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Kim, Junseok. "Improved Properties of Poly (Lactic Acid) with Incorporation of Carbon Hybrid Nanostructure". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/81415.
Pełny tekst źródłaStreszczenie:
Poly(lactic acid) is biodegradable polymer derived from renewable resources and non-toxic, which has become most interested polymer to substitute petroleum-based polymer. However, it has low glass transition temperature and poor gas barrier properties to restrict the application on hot contents packaging and long-term food packaging. The objectives of this research are: (a) to reduce coagulation of graphene oxide/single-walled carbon nanotube (GOCNT) nanocomposite in poly(lactic acid) matrix and (b) to improve mechanical strength and oxygen barrier property, which extend the application of poly(lactic acid).
Graphene oxide has been found to have relatively even dispersion in poly(lactic acid) matrix while its own coagulation has become significant draw back for properties of nanocomposite such as gas barrier, mechanical properties and thermo stability as well as crystallinity. Here, single-walled carbon nanotube was hybrid with graphene oxide to reduce irreversible coagulation by preventing van der Waals of graphene oxide. Mass ratio of graphene oxide and carbon nanotube was determined as 3:1 at presenting greatest performance of preventing coagulation. Four different weight percentage of GOCNT nanocomposite, which are 0.05, 0.2, 0.3 and 0.4 weight percent, were composited with poly(lactic acid) by solution blending method. FESEM morphology determined minor coagulation of GOCNT nanocomopsite for different weight percentage composites. Insignificant crystallinity change was observed in DSC and XRD data. At 0.4 weight percent, it prevented most of UV-B light but was least transparent. GOCNT nanocomposite weight percent was linearly related to ultimate tensile strength of nanocomposite film. The greatest ultimate tensile strength was found at 0.4 weight percent which is 175% stronger than neat poly(lactic acid) film. Oxygen barrier property was improved as GOCNT weight percent increased. 66.57% of oxygen transmission rate was reduced at 0.4 weight percent compared to neat poly(lactic acid). The enhanced oxygen barrier property was ascribed to the outstanding impermeability of hybrid structure GOCNT as well as the strong interfacial adhesion of GOCNT and poly(lactic acid) rather than change of crystallinity. Such a small amount of GOCNT nanocomposite improved mechanical strength and oxygen barrier property while there were no significant change of crystallinity and thermal behavior found.Master of Science
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Solouki, Bonab Vahab. "Polyurethane (PU) Nanocomposites; Interplay of Composition, Morphology, and Properties". Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1542634359353501.
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Jagtap, Amardeep M. "Investigations on Photophysical Properties of Semiconductor Quantum Dots (CdxHg1-xTe,Ag2S) and their Interactions with Graphene Oxide, Organic Polymer Composites". Thesis, 2016. http://etd.iisc.ac.in/handle/2005/3069.
Pełny tekst źródłaStreszczenie:
The motivation of this thesis is to understand the physical properties of semiconductor quantum dots (QDs) and to get insight on the basic physics of charge separation in composites made from QDs with graphene oxide (GO)/organic semiconductors. The flexion phonon interactions is one of fundamental issues in solid state physics, which has a significant effect on both electrical and optical properties of solid state materials. This thesis investigates the physical properties of aqueous grown QDs through exciton-phonon coupling and non-radiative relaxation of excited carriers which have been carried out by temperature dependent photoluminescence spectroscopy. Several e orts have been made in order to understand the basic physics of photo induced
charge separation in the hybrid systems made from QDs with graphene oxide and organic semiconductors. Investigations on the photoconductivity of the devices made from these hybrid composites have been carried out keeping the motive of its application in nanotechnology. This thesis work is presented in six chapters inclusive of summary and directions for future work.
Chapter 1 discusses the background knowledge and information of the general properties of semiconductor nanostructures, QDs and their hybrid nanocomposites. Chapter 2 deals with the sample preparation and experimental techniques used in this thesis. Chapter 3 elaborates the exciton-phonon scattering and nonradiative relaxations of excited carriers in visible emitting cadmium telluride QDs with help of temperature and size dependent photoluminescence. Chapter 4 presents the investigations on time resolved photoluminescence dynamics and temperature dependent photoluminescence properties of near infrared (NIR) emitting mercury
cadmium telluride (CdHgTe). Chapter 5 discusses the importance of NIR emitting silver sulphide (Ag2S) QDs and gives insight of nonradiative recombinations through defect/trap states. Chapter 6 investigates the excited state interactions between CdHgTe QDs and GO. Chapter 7 focuses on the understanding of basic
physics of charge separation/transfer between poly (3hexylthiophene) and Ag2S QDs.
Chapter 1: Semiconductor nanostructures have attracted significant scientific attention due to their fundamental physical properties and technological interests. Quasi zero dimensional nanocrystals or quantum dots (QDs) have shown unique optical and electrical properties compared to its bulk counterpart. These QDs show discrete energy levels due to the quantum confinement effect hence known as arti cial atoms. Large surface to volume ratio in these QDs is expected to play a crucial role in determing the photo-physical properties. Temperature dependent photoluminescence is a powerful tool for understanding the role of the large surface area on exciton recombination process in QDs. Inorganic QDs combined with different materials like graphene oxide or organic semiconductors forms an exciting class of synthetic materials which integrates the properties of organic and inorganic semiconductors. It is quite important to understand the basic physics of electronic interactions in these composites for its future application in many elds.
Chapter 2: Synthesis of the inorganic QDs, graphene oxide, composites and fabrication of devices is an important and integral part of this thesis. Hydrothermal and three necked ask technique is adopted to get highly dispersible colloidal
quantum dots in solvents. Synthesis of graphene oxide from graphite through oxidation and ultrasonication has been carried out to obtain homogenous dispersed graphene oxide in water. Structural properties have been studied by techniques like X ray diffraction, Raman spectroscopy, X ray photoelectron spectroscopy
and high resolution transmission electron microscopy. Morphological properties are studied by atomic force microscopy and transmission electron microscopy. Optical properties are investigated by absorption spectroscopy, steady state and time resolved photoluminescence spectroscopy. Photoconductivity characteristics are analyzed to understand the basics of enhanced current in the various devices made from QDs composites.
Chapter 3:Investigations on exciton phonon coupling and nonradiative relaxations in various sizes of visible light emitting cadmium telluride (CdTe) QDs size have been presented. Due to the large surface area, QDs are prone to have defect/trap states which can affect the exciton relaxation. Hence, understanding the role of such defect/trap states on photoluminescence is very essential for achieving the optimum optical properties. Temperature dependent (15 300 K) photoluminescence has been used to understand nonradiative relaxation of excited carriers. Thermally activated processes and multiple phonons scattering is thoroughly investigated to understand the quenching of photoluminescence with temperature. The strength of exciton-phonon coupling is investigated which determines the variation in energy bandgap of QDs with temperature. Role of exciton phonon scattering is also discussed to understand the basic physics of photoluminescence line width broadening in QDs.
Chapter 4 and 5: This part of thesis focuses on the size and temperature pho-toluminescence properties of near infra red emitting ternary alloyed CdHgTe and Ag2S QDs. Near infrared emitting semiconductor quantum dots (QDs) have attracted significant scientific and technological interests due to their potential applications in the fields of photosensor, solar energy harvesting cells, telecommunication and biological tissue imaging etc. Structural and photophysical properties of CdHgTe QDs have been analyzed by high resolution transmission electron microscopy, X rayphotoelectron microscopy, photoluminescence decay kinetics and low temperature photoluminescence. Investigations on the nonradiative recombinations through trap/defects states and exciton phonon coupling are carried out in colloidal Ag 2S QDs which emits in the range of 1065 1260 nm. Particularly, the photoluminescence
quenching mechanism with increasing temperature is analyzed in the presence of multiple nonradiative relaxation channels, where the excited carriers are thermally stimulated to the surface defect/trap states of QDs.
Chapter 6 and 7: The aim of these chapters is to understand the basic physics of photo induced charge separation in the hybrid systems made from the inorganic QDs with graphene oxide and organic semiconductors. In chapter 6, CdHgTe QDs are decorated on graphene oxide sheets through physisorption. The excited state electronic interactions have been studied by optical and electrical characterizations in these CdHgTe QDs GO hybrid systems. In chapter 7, investigations are carried out for understanding the basic physics of charge separation in the composites of Ag2S QDs and poly (3hexylthiophene 2,5 diyl)(P3HT). These composites of inorganic organic materials are made by simple mixing with help of ultrasonication technique. Steady state and time resolved photoluminescence measurements are used as powerful technique to gain insight of energy/charge transfer process between P3HT and Ag2S QDs. Furthermore, investigations have been carried out on the photoconductivity of the devices made from these hybrid composites keeping the motive of its application in nanotechnology.
Chapter 8: The conclusions of the work presented in this thesis are coherently summarized in this chapter. Thoughts and prospective for future directions are also summed up.
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Jagtap, Amardeep M. "Investigations on Photophysical Properties of Semiconductor Quantum Dots (CdxHg1-xTe,Ag2S) and their Interactions with Graphene Oxide, Organic Polymer Composites". Thesis, 2016. http://hdl.handle.net/2005/3069.
Pełny tekst źródłaStreszczenie:
The motivation of this thesis is to understand the physical properties of semiconductor quantum dots (QDs) and to get insight on the basic physics of charge separation in composites made from QDs with graphene oxide (GO)/organic semiconductors. The flexion phonon interactions is one of fundamental issues in solid state physics, which has a significant effect on both electrical and optical properties of solid state materials. This thesis investigates the physical properties of aqueous grown QDs through exciton-phonon coupling and non-radiative relaxation of excited carriers which have been carried out by temperature dependent photoluminescence spectroscopy. Several e orts have been made in order to understand the basic physics of photo induced
charge separation in the hybrid systems made from QDs with graphene oxide and organic semiconductors. Investigations on the photoconductivity of the devices made from these hybrid composites have been carried out keeping the motive of its application in nanotechnology. This thesis work is presented in six chapters inclusive of summary and directions for future work.
Chapter 1 discusses the background knowledge and information of the general properties of semiconductor nanostructures, QDs and their hybrid nanocomposites. Chapter 2 deals with the sample preparation and experimental techniques used in this thesis. Chapter 3 elaborates the exciton-phonon scattering and nonradiative relaxations of excited carriers in visible emitting cadmium telluride QDs with help of temperature and size dependent photoluminescence. Chapter 4 presents the investigations on time resolved photoluminescence dynamics and temperature dependent photoluminescence properties of near infrared (NIR) emitting mercury
cadmium telluride (CdHgTe). Chapter 5 discusses the importance of NIR emitting silver sulphide (Ag2S) QDs and gives insight of nonradiative recombinations through defect/trap states. Chapter 6 investigates the excited state interactions between CdHgTe QDs and GO. Chapter 7 focuses on the understanding of basic
physics of charge separation/transfer between poly (3hexylthiophene) and Ag2S QDs.
Chapter 1: Semiconductor nanostructures have attracted significant scientific attention due to their fundamental physical properties and technological interests. Quasi zero dimensional nanocrystals or quantum dots (QDs) have shown unique optical and electrical properties compared to its bulk counterpart. These QDs show discrete energy levels due to the quantum confinement effect hence known as arti cial atoms. Large surface to volume ratio in these QDs is expected to play a crucial role in determing the photo-physical properties. Temperature dependent photoluminescence is a powerful tool for understanding the role of the large surface area on exciton recombination process in QDs. Inorganic QDs combined with different materials like graphene oxide or organic semiconductors forms an exciting class of synthetic materials which integrates the properties of organic and inorganic semiconductors. It is quite important to understand the basic physics of electronic interactions in these composites for its future application in many elds.
Chapter 2: Synthesis of the inorganic QDs, graphene oxide, composites and fabrication of devices is an important and integral part of this thesis. Hydrothermal and three necked ask technique is adopted to get highly dispersible colloidal
quantum dots in solvents. Synthesis of graphene oxide from graphite through oxidation and ultrasonication has been carried out to obtain homogenous dispersed graphene oxide in water. Structural properties have been studied by techniques like X ray diffraction, Raman spectroscopy, X ray photoelectron spectroscopy
and high resolution transmission electron microscopy. Morphological properties are studied by atomic force microscopy and transmission electron microscopy. Optical properties are investigated by absorption spectroscopy, steady state and time resolved photoluminescence spectroscopy. Photoconductivity characteristics are analyzed to understand the basics of enhanced current in the various devices made from QDs composites.
Chapter 3:Investigations on exciton phonon coupling and nonradiative relaxations in various sizes of visible light emitting cadmium telluride (CdTe) QDs size have been presented. Due to the large surface area, QDs are prone to have defect/trap states which can affect the exciton relaxation. Hence, understanding the role of such defect/trap states on photoluminescence is very essential for achieving the optimum optical properties. Temperature dependent (15 300 K) photoluminescence has been used to understand nonradiative relaxation of excited carriers. Thermally activated processes and multiple phonons scattering is thoroughly investigated to understand the quenching of photoluminescence with temperature. The strength of exciton-phonon coupling is investigated which determines the variation in energy bandgap of QDs with temperature. Role of exciton phonon scattering is also discussed to understand the basic physics of photoluminescence line width broadening in QDs.
Chapter 4 and 5: This part of thesis focuses on the size and temperature pho-toluminescence properties of near infra red emitting ternary alloyed CdHgTe and Ag2S QDs. Near infrared emitting semiconductor quantum dots (QDs) have attracted significant scientific and technological interests due to their potential applications in the fields of photosensor, solar energy harvesting cells, telecommunication and biological tissue imaging etc. Structural and photophysical properties of CdHgTe QDs have been analyzed by high resolution transmission electron microscopy, X rayphotoelectron microscopy, photoluminescence decay kinetics and low temperature photoluminescence. Investigations on the nonradiative recombinations through trap/defects states and exciton phonon coupling are carried out in colloidal Ag 2S QDs which emits in the range of 1065 1260 nm. Particularly, the photoluminescence
quenching mechanism with increasing temperature is analyzed in the presence of multiple nonradiative relaxation channels, where the excited carriers are thermally stimulated to the surface defect/trap states of QDs.
Chapter 6 and 7: The aim of these chapters is to understand the basic physics of photo induced charge separation in the hybrid systems made from the inorganic QDs with graphene oxide and organic semiconductors. In chapter 6, CdHgTe QDs are decorated on graphene oxide sheets through physisorption. The excited state electronic interactions have been studied by optical and electrical characterizations in these CdHgTe QDs GO hybrid systems. In chapter 7, investigations are carried out for understanding the basic physics of charge separation in the composites of Ag2S QDs and poly (3hexylthiophene 2,5 diyl)(P3HT). These composites of inorganic organic materials are made by simple mixing with help of ultrasonication technique. Steady state and time resolved photoluminescence measurements are used as powerful technique to gain insight of energy/charge transfer process between P3HT and Ag2S QDs. Furthermore, investigations have been carried out on the photoconductivity of the devices made from these hybrid composites keeping the motive of its application in nanotechnology.
Chapter 8: The conclusions of the work presented in this thesis are coherently summarized in this chapter. Thoughts and prospective for future directions are also summed up.
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Lin, Zheng-Yu, i 林政宇. "Synthesis of SnO2/Graphene hierarchical nanostructure and their gas sensing properties". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/rsmf6w.
Pełny tekst źródłaStreszczenie:
碩士國立中興大學
材料科學與工程學系所
101
In this study, SnO2/Graphene hierarchical nanostructures had been synthesized successfully by a two-step vapor transport method. We not only explore the effects of the different growth time on the resultant structures of graphene, but also observe the morphological evolution to investigate the growth mechanism. The results show that the number of the layers of graphene increased with increasing the growth time when a mixture of methane and nitrogen with a ratio of 90:30 was introduced and the growth temperature was kept at 1000˚C. Moreover, we found that the growth mechanism of grapheme grown on the copper foil in this study is different from that grown by the low pressure chemical vapor deposition (APCVD). Here the granules of C-Cu alloy play an essential role in the growth process of Graphene. When methane is disassociated into ionization species, small graphene grain will grow on the surface of copper foil in the initial stage. The absorption of carbon atoms around the graphene grains will lead to formation of C-Cu alloy that can provide sufficient carbon atom sources for the continuous growth of graphene. For the growth of SnO2 nanowires on the graphene substrate, a thin layer of gold was deposited on the graphene substrate and SnO2 nanowires were grown by an Au-catalytic VLS growth mechanism. The structure of SnO2 nanowires is confirmed to be tetragonal rutile and the growth direction is along [021]. For gas sensing measurements, sensors based on graphene and SnO2/Graphene hierarchical nanostructures are fabricated and their sensing properties to NO2 gas with various concentrations were measured at different operation temperatures. The results show that the SnO2/Graphene hierarchical nanostructures have higher sensitivities than graphene, which can be attributed to their high surface-to-volume ratios, and the formation of numerous Schottky barriers between SnO2 and Graphene that provides the advantage of catching electrons.
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Chiou, Yu-Ling, i 邱昱菱. "The Fabrication and Photoelectric Properties of ZnO Nanostructure/Reduced Graphene Oxide Hybrid Structures". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/r32ve5.
Pełny tekst źródłaStreszczenie:
碩士國立臺南大學
材料科學系碩士班
102
Zinc oxide has many excellent piezoelectric, optic, electric, and photoelectric properties and has been widely applied on various functional devices. Graphene is a new carbon structure with good electrical and optical properties. The chemical reduction method is the most common way to fabricate large scale of graphene oxide (GO). This study reports both hydrothermal method and aqueous solution method to synthesize Zn/RGO hybrid films, and explores the effect of preparation parameters on the composition and structure of the hybrid films. UV photocurrent measurement, SEM, XRD and EDS are employed to analyze the characteristic of the hybrid materials. Finally, we combine this hybrid material with Ag nanowire electrode to make UV photodetector and discuss the dependence of photoelectric performance on the properties of the hybrid films. Drom the results of experiment, we find that different conditions of preparation can affect the distribution and morphology of ZnO. By changing the precursor concentration to control ZnO nanostructures distributing on NPs-RGO, the ZnO can turn from particle structure into rod structure. The higher concentration of precursor can result in a better UV photodetector performance. By changing the reaction temperature for synthesizing hybrid films, it is found that higher reaction temperature can get higher degree of ZnO crystallization and a consequent shorter response time in the fabricated UV photodetector. Because of the high temperature and high pressure in hydrothermal method, the prepared hybrid structure can give a better UV photodetector performance. By transferring the hybrid films to PMMA substrate, a fraction of Ag nanowires are embedded into the polymer. Thus the hybrid structure and Ag nanowire electrode have a better contact, which helps the carrier move faster and leads to a high photocurrent and a short response time in the photodetector.
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Ajayi, Obafunso. "Optical Studies of Excitonic Effects at Two-Dimensional Nanostructure Interfaces". Thesis, 2017. https://doi.org/10.7916/D87H1K4K.
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Atomically thin two-dimensional nanomaterials such as graphene and transition metal dichalcogenides (TMDCs) have seen a rapid growth of exploration since the isolation of monolayer graphene. These materials provide a rich field of study for physics and optoelectronics applications. Many applications seek to combine a two dimensional (2D) material with another nanomaterial, either another two dimensional material or a zero (0D) or one dimensional (1D) material. The work in this thesis explores the consequences of these interactions from 0D to 2D. We begin in Chapter 2 with a study of energy transfer at 0D-2D interfaces with quantum dots and graphene. In our work we seek to maximize the rate of energy transfer by reducing the distance between the materials. We observe an interplay with the distance-dependence and surface effects from our halogen terminated quantum dots that affect our observed energy transfer. In Chapter 3 we study supercapacitance in composite graphene oxide- carbon nanotube electrodes. At this 2D-1D interface we observe a compounding effect between graphene oxide and carbon nanotubes. Carbon nanotubes increase the accessible surface area of the supercapacitors and improve conductivity by forming a conductive pathway through electrodes. In Chapter 4 we investigate effective means of improving sample quality in TMDCs and discover the importance of the monolayer interface. We observe a drastic improvement in photoluminescence when encapsulating our TMDCs with Boron Nitride. We measure spectral linewidths approaching the intrinsic limit due to this 2D-2D interface. We also effectively reduce excess charge and thus the trion-exciton ratio in our samples through substrate surface passivation. In Chapter 5 we briefly discuss our investigations on chemical doping, heterostructures and interlayer decoupling in ReS₂. We observe an increase in intensity for p-doped MoS₂ samples. We investigated the charge transfer exciton previously identified in heterostructures. Spectral observation of this interlayer exciton remained elusive in our work but provided the motivation for our work in Chapter 4. We also discuss our preliminary results on interlayer decoupling in ReS₂.
Książki na temat "Graphene Nanostructure - Photophysical Properties"
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Ali, Nasar, Mahmood Aliofkhazraei, William I. Milne, Cengiz S. Ozkan i Stanislaw Mitura. Graphene Science Handbook: Nanostructure and Atomic Arrangement. Taylor & Francis Group, 2016.
Znajdź pełny tekst źródła
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Ali, Nasar, Mahmood Aliofkhazraei, William I. Milne, Cengiz S. Ozkan i Stanislaw Mitura. Graphene Science Handbook: Nanostructure and Atomic Arrangement. Taylor & Francis Group, 2016.
Znajdź pełny tekst źródłaCzęści książek na temat "Graphene Nanostructure - Photophysical Properties"
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Naseem, Z., K. Sagoe-Crentsil i W. Duan. "Graphene-Induced Nano- and Microscale Modification of Polymer Structures in Cement Composite Systems". W Lecture Notes in Civil Engineering, 527–33. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_56.
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AbstractRedispersible polymers such as ethylene–vinyl acetate copolymer (EVA) have attracted attention in construction due to their enhanced flexural strength, adhesion, flexibility and resistance against water penetration. However, EVA particles cluster in a highly alkaline cementitious matrix and exhibit poor interaction with the cement matrix. The underlying mechanism of poor dispersibility of EVA is attributed to hydrophobic groups of polymers, a variation in the adsorption rate and molecular diffusion to the interface where they cluster together. This phenomenon can negatively affect the fresh properties of cement and produce a weak microstructure, adversely affecting the resulting composites’ performance. This study highlights how graphene oxide (GO) nanomaterial alters the nano- and microscale structural characteristics of EVA to minimize the negative effects. Transmission electron microscopy (TEM) revealed that the GO sheets modify EVA’s clustered nanostructure and disperse it through electrostatic and steric interactions. Furthermore, scanning electron microscopy (SEM) confirmed altered microscale structural characteristics (viz. surface features) by GO. The altered and enhanced material scale engineering performance, such as the compressive strength of the resulting cement composite, was notable.
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Kalkal, Ashish, i Gopinath Packirisamy. "Recent Advances on Carbon Nanostructure-Based Biosensors". W Current and Future Developments in Nanomaterials and Carbon Nanotubes, 19–38. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815050714122030005.
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Carbon-based nanostructured materials have derived substantial attention as novel functional materials towards the fabrication of various biosensing platforms owing to their interesting physicochemical and optoelectronic properties, as well as desired surface functionalities. These nanomaterials provide increased and oriented immobilization of biomolecules along with maintaining their biological activity in view of their lower cytotoxicity and higher biocompatibility. The integration of carbon nanomaterials with biosensing platforms has provided new opportunities and paved the way for the efficient detection of various biomolecules and analytes. These nanostructured materials-based biosensors have improved biosensing characteristics, including broader linear detection range, lower detection limit, better selectivity, and higher sensitivity. This chapter summarizes the results of different electrochemical and fluorescent biosensors related to various nanostructured carbon materials, namely carbon nanotubes (CNTs), graphene and its derivatives (reduced graphene oxide (rGO), graphene oxide (GO), graphene quantum dots (GQDs) and carbon dots (CDs).
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Jahid Akhtar, Abu. "Graphene-Based Materials for Supercapacitor". W Supercapacitors [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98011.
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Graphene, a one-atomic-thick film of two-dimensional nanostructure, has piqued the attention of researchers due to its superior electrical conductivity, large surface area, good chemical stability, and excellent mechanical behaviour. These extraordinary properties make graphene an appropriate contender for energy storage applications. However, the agglomeration and re-stacking of graphene layers due to the enormous interlayer van der Waals attractions have severely hampered the performance of supercapacitors. Several strategies have been introduced to overcome the limitations and established graphene as an ideal candidate for supercapacitor. The combination of conducting polymer (CP) or metal oxide (MO) with graphene as electrode material is expected to boost the performance of supercapacitors. Recent reports on various CP/graphene composites and MO/graphene composites as supercapacitor electrode materials are summarised in this chapter, with a focus on the two basic supercapacitor mechanisms (EDLCs and pseudocapacitors).
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Khalaj, Zahra, Majid Monajjemi i Mircea V. Diudea. "Main Allotropes of Carbon". W Sustainable Nanosystems Development, Properties, and Applications, 185–213. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-0492-4.ch006.
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Carbon allotropes can be classified according to the carbon atom hybridization. In principle, there are different ways, based on various parameters, such as range dimensionality, type of chemical bonds, etc. which can be used to classify carbon nanostructures. Classifications vary function of the field of nanostructure applications. In a point of view, one can classify the carbon allotropes by the type of carbon atom hybridation. This chapter is a brief review introduction to some major allotropes: graphene/graphite, carbon nanotubes, diamond and amorphous carbon. In addition, Chemical Vapor Deposition (CVD) techniques, frequently used for synthesizing these structures are discussed. The influence of some important experimental parameters on the growth of high quality diamond and diamond-like carbon DLC are also investigated.
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Panda, Debabrata, i Krunal M. Gangawane. "Next-Generation Energy Storage and Optoelectronic Nanodevices". W Current and Future Developments in Nanomaterials and Carbon Nanotubes, 223–39. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815050714122030016.
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Among the variety of nanostructures that have been explored as a favorable material for the application of higher energy storage devices as supercapacitors, catalysts in high-performance batteries, proton exchange membranes in fuel cells, optoelectronic devices, and so on, 2D & 3D nanostructure of graphene-based derivatives, metal oxides and dichalcogenides have received the most potential attention for building high-performance nano-devices due to their extraordinary properties. Over the past decade, several efforts have been implemented to design, develop, and evaluate electrodes' structures for enhanced energy storage devices. A significant modification has achieved the remarkable performance of these synthesized devices in terms of energy storage capacity, conversion efficiency, and the reliability of the devices to meet practical applications' demands. Light-emitting diode (LED) in quantum well or quantum dots is considered an important aspect for an enhanced optoelectronic device. This current study outlines different 3D nanostructures for next generation energy storage devices. It provides a systematic summary of the advantages of 3D nanostructures in perspective to next-generation energy storage devices, photocatalytic devices, solar cells, a counter electrode for metal-ion batteries, and supercapacitors, optoelectronic nano-devices.
Streszczenia konferencji na temat "Graphene Nanostructure - Photophysical Properties"
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Alavi, Seyed Khalil, Boris V. Senkovskiy, Markus Pfeiffer, Danny Haberer, Felix R. Fischer, Klaus Meerholz, Yoichi Ando, Alexander Gruneis i Klas Lindfors. "Graphene Nanoribbons: From Photophysical Properties Towards Devices". W 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). IEEE, 2019. http://dx.doi.org/10.1109/cleoe-eqec.2019.8872183.
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Avila, Antonio F., Camila Goncalves i Glaucio Carley. "Hybrid Carbon/Epoxy Composites with Interlocking Properties: The Graphene Nanostructure Morphology Investigation". W 55th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2014. http://dx.doi.org/10.2514/6.2014-0468.
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Nedumthakady, Nithin, Pragna Bhaskar i Vanessa Smet. "Magneto-Assisted Graphene Reinforcement: A New Method to Enhance Nanostructure and Properties of Electrodeposited Copper". W 2023 IEEE 73rd Electronic Components and Technology Conference (ECTC). IEEE, 2023. http://dx.doi.org/10.1109/ectc51909.2023.00195.
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Nakarmi, Sushan, i V. U. Unnikrishnan. "Influence of Strain States on the Thermal Transport Properties of Single and Multiwalled Carbon Nanostructures". W ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-88620.
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The increasing demand for system miniaturization and high power density energy produces excessive thermal loads on electronic devices with significant mechanical strain. Carbon Nanotubes (CNTs) based devices are found to have excellent thermal transport properties that makes them attractive for thermal management of these miniaturized nano-electronic devices under extreme environments. These conductive nanostructure (carbon nanotubes, graphene, etc.) are often embedded in polymers or other high-strain alloys (the matrix phase), and are used as bridging materials for conductivity (electrical and thermal) with strain resiliency. The effect of strain on the thermal transport properties of these nanostructures have often been overlooked and will be the focus of this work. The thermal conductivity of the nanostructure is obtained in LAMMPS using the Heat-Bath method, which is a reverse non-equilibrium molecular dynamics (RNEMD) simulation strategy. In RNEMD, constant amount of heat is added to and removed from hot and cold regions and the resultant temperature gradient is measured. The effect of strain on the thermal conductivity of the single and multiwalled nanostructures of various configurations will be discussed with specific emphasis on the phonon density of states of nanotubes at different strain states.
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Moulod, Mohammad, i Gisuk Hwang. "Comparative Studies on Water Self-Diffusivity Confined in Graphene Nanogap: Molecular Dynamics Simulation". W ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2016 Heat Transfer Summer Conference and the ASME 2016 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icnmm2016-7962.
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Fundamental understanding of the water in graphene is crucial to optimally design and operate the sustainable energy, water desalination, and bio-medical systems. A numerous atomic-scale studies have been reported, primarily articulating the surface interactions (interatomic potentials) between the water and graphene. However, a systematic comparative study among the various interatomic potentials is rare, especially for the water transport confined in the graphene nanostructure. In this study, the effects of different interatomic potentials and gap sizes on water self-diffusivity are investigated using the molecular dynamics simulation at T = 300 K. The water is confined in the rigid graphene nanogap with the various gap sizes Lz = 0.7 to 4.17 nm, using SPC/E and TIP3P water models. The water self-diffusivity is calculated using the mean squared displacement approach. It is found that the water self-diffusivity in the confined region is lower than that of the bulk water, and it decreases as the gap size decreases and the surface energy increases. Also, the water self-diffusivity nearly linearly decreases with the increasing surface energy to reach the bulk water self-diffusivity at zero surface energy. The obtained results provide a roadmap to fundamentally understand the water transport properties in the graphene geometries and surface interactions.
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Resnick, Alex, Jungkyu Park, Biya Haile i Eduardo B. Farfán. "Three-Dimensional Printing of Carbon Nanostructures". W ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11411.
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Abstract Multi-layered carbon nanostructures are the next leap for many advanced consumer and industrial applications that require both high strength and uniquely high electrical and thermal properties. Applications of three-dimensional (3D) carbon nanostructures have already been theorized to include wearable technology, processor chip heat transfer material, and flexible electronics. 3D carbon nanostructures appear in the form of carbon nanotubes (CNTs) and layered graphene tiers, however, many structures previously examined have been limited to one or two graphene layers or non-repeatable structured patterns. Many of the electrical and thermal properties of CNTs are still being investigated, but the initial studies demonstrate promising results such as the thermal conductivity ranging in the thousands W/m-K. Developing new ways to fabricate these structures at a reasonable cost has become a primary focus for graphene-based research. In this study, 3D carbon nanostructure samples are 3D printed using laser lithography, then a series of high temperature furnace burns and Nickel Chemical Vapor Deposition (CVD) is utilized to leave a previously multi-species structure as a solely carbon-species structure with mostly carbon sp-2 bonds. CVD has proven to be a leading method for forming graphene due to the ability to control graphene nucleation across larger surfaces and structures. Nanoscale 3D printing of carbon structures also allows for a great degree of freedom towards the creation of repeatable patterns or structures that are currently trying to be achieved in other studies. This study employs the use of controlled cleanroom environments with cutting edge technology and machines to fabricate the 3D carbon nanostructures.