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Sahakalkan, Serhat [Verfasser], and David [Akademischer Betreuer] Wharam. "Spin Transport in Carbon Nanotubes with Circular Nanodot Contacts / Serhat Sahakalkan ; Betreuer: David Wharam." Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1182985432/34.
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Kim, Tak Hyuan. "Synthesis and Applications of Carbon Nanodots." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/366029.
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The study was set out to explore the synthesis of Carbon Nanodots (CDs) and their potential in practical applications in lighting, sensing and biological areas. Toxicity evaluation was also involved in the investigation, because of its profound importance in the real-world applications of CDs. The study sought to answer the following questions: 1) how does the photoluminescence change when we vary the surface functional moieties and change the chemical compositions by doping? 2) For light applications, are the CDs stable enough under the operational conditions? If not, how to improve their stability? 3) How to impart sensing capabilities to CDs through surface design? 4) Are CDs really non-toxic? How does their toxicity change when surface functional groups vary? Through a series of studies, namely 1) salt-encapsulation for enhancing UV- and thermostability; 2) Transparent, yellow-emitting CD films for white light LEDs; 3) Amine-rich CDs for sensing amphetamine precursors; 4) Biocompatible CDs exhibiting antiproliferative activities, I have demonstrated that the emission of the CDs are controllable by modifying the particles surface moieties, and the excitation dependency of the emission can be refined by either fractionation or purification. Despite of what is often reported about the toxicity of CDs, the toxicity of the CDs depends on the surface functional groups of CDs and the biological entities. However, the toxicity of the CDs may be utilized as a therapeutic purpose. Further demonstration on the lighting and sensing may project the bright future of carbon based nanoparticles as an excellent candidate for these applications.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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Sciortino, Alice. "The Fundamental Photophysics of Fluorescent Carbon Nanodots." Doctoral thesis, Università di Catania, 2019. http://hdl.handle.net/10761/4125.
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Carbon Nanodots (CDs) are a new protagonist of carbon-based nanoscience by which the paradigm of carbon as a black material unable to emit light has been completely revolutionised. They have been emerging as a new frontier in Nanoscience at the beginning of 2000s, and their potential is evident from the explosion of the number of studies, now ranging in the thousands per year. CDs are nanoparticles composed by carbon, oxygen and hydrogen with a size smaller than 10 nm. Their most important hallmark is their strong luminescence, which is combined with many additional benefits as the low cost and ease of synthesis, the high water solubility, the biocompatibility and non-toxicity, the great sensitivity to the external environment, and a marked electron donating and accepting capabilities. The combination of all of these characteristics guarantees the possibility to use CDs in a very broad range of applications which encompasses many different fields as optoelectronics or sensing. Actually, the term CDs includes nanomaterials which display a wide range of possible structures and variable optical properties. Indeed, in the literature, it is common to find different sub-types of CDs: they can be graphitic, amorphous, disks of graphene or with a C3N4 core; they can be hydrophilic or hydrophobic; they can emit blue, green, or red light; their emission can be independent of the excitation wavelength, or more commonly tunable (peak of the emission depends on the excitation wavelength); their fluorescence intensity can be sensitive to one particular ion in solution or they respond to a variety of interactions with other systems, such as carbon nanotubes. Besides, CDs can be synthesized by many different procedures which yield subtypes of CDs capable of emitting fluorescence at different wavelengths. In all the synthesis approaches, their surface is passivated by external agents to get bright emission. All of this leads to the existence in the literature of diverse sub-types of CDs with different core and surface structure, and different specific optical characteristics. Despite of this, there are common characteristics which are recurrent almost in every type of CDs as the small size and the core+corona structure which are found to be crucial to obtain CDs with a visible photoluminescence with a high emission efficiency. Carbon dots research is still in a developing phase despite thousands of studies have already been published on the subject, and several scientific open questions exist about their optical behaviour, the fundamental nature of the electronic states, the key factors determining their bright fluorescence, and the relation between structure and emission. As a consequence, a large effort is in progress to find the most effective ways to tailor them for specific applications.
In this Thesis, we carried out an investigation of the fundamental physics of different families of CDs with the aim to achieve an exhaustive understanding of their entire photocycle from femtosecond to the steady state. To do this, it was necessary to relate the optical properties to the structural ones, and to study the influence of various possible interactions with external agents. Thus, electronic transitions of CDs having different structures or exposed to different environments have been studied by the combined use of several experimental techniques. In particular, as an important novelty in the field, a variety of new methods which involve ultrafast spectroscopic techniques have been used. Ultrafast spectroscopy is a powerful tool to investigate in real time electronic and vibrational processes with picosecond and femtosecond time resolution. With the use of these methods it was possible to map the photocycle of CDs revealing several dynamics which occur on short time scale as solvation, charge transfer, and fluorescence quenching.
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BRUNO, Federico. "OPTICAL SENSING OF POLLUTANTS BY FLUORESCENT CARBON NANODOTS." Doctoral thesis, Università degli Studi di Palermo, 2022. http://hdl.handle.net/10447/560721.
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Carrara, Serena. "Towards new efficient nanostructured hybrid materials for ECL applications." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF016/document.
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Cette thèse vise à développer de nouveaux matériaux hybrides pour les applications en électrochimiluminescence. Les propriétés électrochimiluminescentes de nouveaux complexes de Pt(II) et d’Ir(III) ont été explorés comme alternative aux marqueurs existants. En plus, la combinaison de complexes et de carbon nanodots portant des groupes primaires ou tertiaires à la surface comme espèces coréactives a abouti à une stratégie intéressante pour éliminer la TPrA. Les carbon nanodots dans un systéme lié par liaison covantent avec complexes métalliques sont non seulement un support innocent pour les espèces actives d’ECL, mais agissent également comme coréactif, se révélant être une plateforme auto-améliorante en ECL. Enfin, un véritable immunoessai pour la détection des marqueurs cardiaques a été mis au point avec une sensibilité et une stabilité accrues pour les applications de détection biologique et biomédicale. La même technologie peut alors être appliquée à une variété d’autres analytes, ouvrant ainsi le site à d’autres dosagesThis doctoral dissertation aim to develop new hybrid materials for ECL applications. In the field of metal complexes, the electrochemiluminescent properties of new Pt(II) and Ir(III) complexes were investigated as alternative of existing complexes. Passing to nanomaterials, the combination of labels and NCNDs bearing primary or tertiary groups on the surface as alternative co-reactant species resulted an interesting strategy to eliminate the toxic TPrA. In particular, NCNDs in covalently linked system with metal complexes is not only an innocent carrier for ECL active species, but act also as co-reactant in the ECL process, revealing itself an ECL self-enhancing platform. Finally, a real immunoassay for cardiac marker detection has been built with enhanced sensitivity and stability, which is of fundamental importance for biological and bio-medical detection applications. The same technology can be applied to a variety of other analytes opening the venue to other assays
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Yeom, Sin Hea. "TEMPERATURE-DEPENDENT TUNABLE PHOTOLUMINESCENCE PROPERTIES OF CARBON NANODOTS DERIVED FROM POLYETHYLENE GLYCOL." UKnowledge, 2014. http://uknowledge.uky.edu/chemistry_etds/46.
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Fluorescent carbon dots (C-dots) are well known for their low cell-cytotoxicity, biocompatibility, low preparation cost, excitation dependent photoluminescence, and excellent photostability. Typically, raw C-dots have low quantum efficiency and thus researchers have been utilizing biocompatible polymers such as polyethylene glycol (PEG) as a passivation agent in order to increase fluorescence signal. In this work, we report fluorescent self-passivated carbon nanodots (CNDs) synthesized from PEG by using it as a carbon source as well as a passivating agent. Importantly, the addition of graphene quantum dots (GQDs) during the synthesis of self-passivated CNDs can tune photoluminescence property. The results of bioimaging and cytotoxicity test of self-passivated CNDs hold promises for biomedicine applications.
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Newman, Peter Lionel Harry. "Carbon Nanotubes for Bone Tissue Engineering." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16308.
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Biological tissues are compositionally and structurally exquisite – a complex network of proteins and cells organised with molecular-precision. Unfortunately, in the absence of an organ transplant or tissue graft, there are no technologies that can completely repair or restore this complex system when it fails. With the hopes of regenerating failing tissue, tissue engineers have developed scaffold structures able to support cell life. As yet, these structures are unable to recreate the complexities of the biological environment, limiting the success of this approach. Nanotechnologies have realised methods to make materials with defined nanoscale properties. Continued research may lead to sophisticated nanobiomaterials, with properties that rival the complexities of biological environments and improve tissue regeneration. To this end, we explored the use of carbon nanotubes (CNTs) within the field of tissue engineering. We investigated the use of 3D CNT scaffolds in bone tissue engineering using strong and porous ceramic scaffold structures coated with CNTs. We abate limitations in previous fabrication methods limiting coating of CNTs throughout porous structures. We demonstrate these surfaces are high quality aligned CNTs, are non toxic and able to support attachment, spreading and proliferation of adipose derived stem cells (ASCs) and human osteoblasts. Following the development of a 3D CNT material, we investigated the potential for using CNTs to create well-defined nanoenvironments capable of regulating cell differentiation. This research is the first report of non-biased quantitative measurement of cell shape during long term differentiation. In contrast to previous techniques, it allows direct measurement of shape rather than that of the underlying substrate. This approach offers novel insights into the relationship between the nanoenvironment, cell shape and cell differentiation. The novel nanomaterials presented in this thesis, demonstrate the potential of nanotechnologies for artificially engineered tissues and organs. Continued research of nanomaterials promises to better recreate the complexities of the biological environment, instructing healthy regenerative processes and promoting tissue function.
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Rolihlahla, Bangile Noel. "Electrochemistry and photophysics of carbon nanodots-decorated nigs(Ni(In, Ga)Se2) quantum dots." university of western cape, 2020. http://hdl.handle.net/11394/7309.
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>Magister Scientiae - MScCurrently, non-renewable sources are mostly used to meet the ever-growing demand for energy. However, these sources are not sustainable. In addition to these energy sources being not sustainable, they are bad for the environment although the energy supply sectors highly depend on them. To address such issues the use of renewable energy sources has been proven to be beneficial for the supply of energy for the global population and its energy needs. Advantageous over non-renewable sources, renewable energy plays a crucial role in minimizing the use of fossil fuel and reduces greenhouse gases. Minimizing use of fossil fuels and greenhouse gases is important, because it helps in the fight against climate change. The use of renewable energy sources can also lead to less air pollution and improved air quality. Although solar energy is the most abundant source of renewable energy that can be converted into electrical energy using various techniques, there are some limitations. Among these techniques are photovoltaic cells which are challenged by low efficiencies and high costs of material fabrication. Hence, current research and innovations are sought towards the reduction of costs and increasing the efficiency of the renewable energy conversion devices.
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Li, Yibing. "Graphitic Carbon-Based Functional Nanomaterials for Environmental Remediation and Energy Conversion Applications." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/366091.
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Carbon-based nanomaterials have attracted significant attention due to their unique optical, electrical, thermal and mechanical properties. In recent years, a large number of carbon-based nanomaterials have been investigated including carbon nanotubes, graphitic carbon nitride (g-C3N4), graphene, carbon nanofibers, carbon nanodots (CNDs), heteroatom-doped carbon, and carbon-based materials obtained from biomass etc. The unique and superior properties of such carbon-based materials make them useful for a wide range of applications in the fields such as environmental remediation and energy conversions. Although significant progress has been made over the past decade or so, few drawbacks of carbon-based materials still remain unresolved. For example, as a photocatalyst, the weak van der Waals interactions between adjacent conjugated planes of g-C3N4 and poor electronic properties affect negatively on the photocatalytic activity. Despite a variety of synthetic methods have been investigated, to fabricate undoped and doped carbon-based materials, the efficiency and level of control on the resultant products are far from satisfactory. Majority of these approaches either involve tedious and complex experimental procedures or require using harsh reaction conditions, or possessing low yield production. Furthermore, to achieve heteroatom-doped carbon-based materials, the reported approaches almost exclusively require the use of synthetic chemicals as carbon and heteroatom sources, respectively. The large-scale application of fuel cells and dye-sensitized solar cells (DSSCs) using Pt-based catalysts is hindered by the inherent disadvantages of Pt such as high cost, scarcity and low resistance to crossover effect of methanol molecule. It is therefore highly desirable to realize heteroatom doping by simple, low-cost, high yield and environmentally benign synthesis methods for fabrication of commercially viable carbon-based materials for applications in solar cells and fuel cells.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Yan, Huijie [Verfasser], and Alf [Akademischer Betreuer] Mews. "Triple labelled gold nanoparticles and fluorescent carbon nanodots as platforms for cell/nanoparticles interaction studies / Huijie Yan ; Betreuer: Alf Mews." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/1215840527/34.
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Meiling, Till Thomas [Verfasser], Ilko [Akademischer Betreuer] Bald, and Hans-Gerd [Akademischer Betreuer] Löhmannsröben. "Development of a reliable and environmentally friendly synthesis for fluorescence carbon nanodots : preparation and characterisation of excellent and well-defined carbon nanodots by a fast, simple and cost-efficient synthesis method; with special focus on future exploration and large scale applications / Till Thomas Meiling ; Ilko Bald, Hans-Gerd Löhmannsröben." Potsdam : Universität Potsdam, 2018. http://d-nb.info/1219578592/34.
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Jiang, Zhoufeng Jiang. "Zero-dimensional and two-dimensional colloidal nanomaterials and their photophysics." Bowling Green State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1522964027555741.
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Yan, Huan. "MICRO- AND NANO-MATERIALS FOR DRUG DELIVERY AND BIOIMAGING APPLICATIONS." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1428155172.
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Panta, Uday. "Charge Separation in Nano-diamonds: DFT Study." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1594381914885325.
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RIGONI, FEDERICA. "EXPLORING DETECTION LIMITS AND RESPONSE TIME SCALES OF CHEMIRESISTOR GAS SENSORS BASED ON CARBON NANOTUBE AND HYBRID LAYERS." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/262413.
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Crucial features in gas sensors for environmental monitoring are the gas sensitivity in the low ppb range and the ability to discriminate variations of a certain polluting gas from other interfering gases.
Monitoring of ammonia gas concentrations is mandatory to reduce the hazard for human health and vegetation determined by the widespread use of ammonia derivatives as agricultural nitrogen fertilizers, industrial production and traffic. In particular, ammonia, besides being a toxic molecule is one of the main precursors of secondary fine particulate matter (PM10, PM2.5). Ammonia could hence be used as a local marker of secondary fine particulate formation, allowing indirect control of particulate emission sources. In spite of this urgency, the detection of NH3 concentrations in urban areas with chemiresistor gas sensors (CGSs) has been so far widely overlooked, since the average levels are usually low, i.e. in the 20-30 ppb range, while the CGSs are generally tested by exposure to ammonia in the ppm range.
Carbon nanotubes (CNTs), discovered more than 20 years ago, are well known and studied systems for many applications, among which (of course) gas sensing. With respect to commercial electrochemical sensors (mostly based on metal oxide materials), CNTs show a higher physical and chemical stability, better transport of charge to the electrodes and a wide range of possible hybrid architectures and operational features, among which the operation at room temperature, that make them unique materials for gas detection.
The main goal of this thesis is to increase the sensitivity to [NH3] and to lower the detection limit (DL), exploring sample preparation strategies of low-cost single walled carbon nanotubes (SWCNT)-based gas sensors operating at room temperature, considering also the response to other interfering gases. Furthermore, effects of metal oxide nanoparticles functionalization and gas response of hybrid layers have been also investigated.
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HSIAO, PO-HSUAN, and 蕭伯諼. "Efficient Photodegradation of Dyes Using Carbon-Nanodot Heterostructure." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/zxusn6.
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碩士國立暨南國際大學
應用材料及光電工程學系
106
Abstract The semiconductor heterostructures exhibited extremely excellent properties such as photovoltaics, energy materials, biomedicine, and environmental protection etc. In this study, a fast and simple two-step process of sonication and post-thermal was used to prepare functional Carbon-Nanodots. With the advantages of high photo-sensitivity, photo-resistance, and high yield 48.6 %, it was far exceeding the traditional thermal process [9-11]. Carbon-Nanodot were composed of graphitic crystal structures which was modified with functional groups such as Carbonyl group, Hydroxy group, etc. The average particle size of Carbon-Nanodot was about 5.68 nm, and the energy gap was about 3.45 eV ,and it possessed superior fluorescent characteristics and sensitivity. Heterostructure of Carbon-Nanodot/silicon nanowire which was prepared by drop-coating method provided super hydrophilic property (with contact angle < 4o), and demonstrated that contact area between dye solution and photocatalyst were large, it was beneficial to enhance the photodegradation efficiency of photocatalyst. Due the its special energy band structure Carbon-Nanodot/silicon nanowires provided excellent broadband photocatalyst effect in visible light (580 nm) and ultraviolet light (420 nm) without adding other chemical agents : The photodegradation rate was 52.4% in 120 minutes at 580 nm light source and 46.9 % in 120 minutes at 420 nm light source. Carbon-Nanodot film /silicon wafer heterostructure photodetector also fabricated by drop-coating method and post-thermal method. Which could accurately control the thickness of the Carbon-Nanodot thin film between 30 to 95 nm. It also showed that high transmittance (95%) on glass substate. The crystal structure of graphite (100) was also discussed with XRD analysis, it demonstrated that Carbon-Nanodot possessed high-crystalline carbon structures and function groups. In addition, the electrical properties and differences of carrier concetration caused by the heterostructure between Carbon-Nanodot and different doped silicon wafer was discussed in this research. The Carbon-Nanodot heterostructure photodetector was designed by its band structure. The photodetection test showed the optimal condition of Carbon-Nanodot film was 40 nm, and also confirmed that Carbon-Nanodot film had the possibility of active layer. The optimal condition caused that the photocurrent gain can be 2.86 mA under the 580 nm light source. The reliability of the heterostructure of Carbon-Nanodot /silicon materials was confirmed. Keyword: Semiconductor, heterostructure, Carbon-Nanodot, silicon-nanowire, photo catalyst, photo-detector
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Hsieh, You-Yang, and 謝佑陽. "Stable Luminescent Carbon-Nanodot Gel Glasses for Eco-Friendly Luminescent Solar Concentrator." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/xxt77c.
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碩士中原大學
物理研究所
107
Luminescent Solar Concentrators, (LSCs) are composed of loaded luminophores and glass waveguides designed to efficiently harvest both incident and diffused solar irradiation devoid of complex solar tracking system. However, most of reported LSCs bank on on colloidal fluorescent materials with noble photophysical properties are frequently comprised of heavy metals and toxic organic solvents. In lieu of this, it is necessary to search for nanomaterials with excellent photo physical, yet considered to cause minimal harm to environment and human health. Carbon Dots (CDs) are environmental friendly nanomaterials but suffers from minimal problems such as concentration-induced quenching (CIQ) and aggregation-induced scattering (AIS). At the same time, the polymer materials used in LSC today have disadvantages such as long-term UV irradiation or heating, which will destroy the photophysical properties and easily hydrolyze the samples after moisture absorption.Therefore, in this study, sulfonated alkyl polymers with excellent heat resistance and stability were bonded to carbon quantum dots, and silanes (-NH2, -NCO, -CH3) with different functional groups, and were selected to react with carbon quantum dots to further explore their light-harvesting properties. The photophysical properties of the CDs used in this research was investigated in order to find the best and optimized conditions for further utilization as a luminescent solar concentrator.
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HSIAO, HSIANG-TSE, and 蕭翔澤. "Carbon Nanodot Additives Realize High-Performance Air-Stable p–i–n Perovskite Solar Cells." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/89wn93.
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碩士明志科技大學
材料工程系碩士班
107
Carbonized bamboo-derived carbon nanodots (CNDs) as efficient additives for application in perovskite solar cells (PSCs) are reported. These carboxylic acid- and hydroxyl-rich CNDs interact with the perovskite through hydrogen bonds and, thereby, promote the carriers’ lifetimes and realize high-performance p–i–n PSCs having the structure indium tin oxide/NiOx/CH3NH3PbI3 (MAPbI3)/PC61BM/BCP/Ag. As a result of interaction between the CNDs and the perovskite, the presence of the nonvolatile CND additive increases the power conversion efficiency (PCE) of the PSC from 14.48% ± 0.39% to 16.47% ± 0.26%. Furthermore, adding urea, a Lewis base, increases the PCE to 20.2%, with values of Jsc, Voc, and FF of 23.76 mA cm−2, 1.079 V, and 78.7%—the result of a significant increase in the crystal size and a lower content of grain boundary defects and, therefore, longer carrier lifetimes. Cells containing these two additives (without encapsulation) exhibit excellent shelf-life and air-stability, maintaining their high PCEs after storage in air—at a temperature of 25 °C and a humidity of 40 %—for over 500 h. This performance is among of the best ever reported for p–i–n PSC devices incorporating carbon-based additives.
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王聖文. "Surface Modification of Reflux-Synthesized Carbon Nanodots." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/sy25ae.
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碩士逢甲大學
化學工程學系
102
In the past few years, the rapid development of worldeconomy leads to energy crisis. Every country started to search for alternative energy sources because of the demanding energy consumption. So far, the highly valued renewable energy source is the solar energy, which is safe, pollution-free, and noiseless. Currently, the solar cellsfor practicaluses are mainly silicon-based. Although their conversion efficiency can reach as high as 30%, the manufacturing cost is too high. Therefore, several organic photovoltaic cells have been developed. Compared toother types of solar cell, polymer solar cells have been widely noted due to their advantages including easy fabrication, low cost, light weight, large area, shape flexibility, , and high optical absorption. Among the polymer solar cells, thosewithpoly (3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blends as the active layer show high energy conversion efficiency. This thesis studied the IPEC (Incident photon to electron conversion efficiency)of the devices using the carbon nanodots to replace the PCBM in the active layer of P3HT.Since the price of the home-made carbon nanodots is about one ten-thousandth that of the PCBM, a large reduction of the device cost is expected if the carbon nanodots function like PCBM. The water soluble carbon nanodots were found to disperse in the organic solvent of DCB after surface modification. However, the measured conversion efficiency of the devices isonly 0.005 at present, much lower than that of the benchmark device.The carbon nanodots are kept being shrunk in size and the surface modifiers, enhanced in electrical conductance.
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Hsu, Pin-Che, and 徐斌哲. "Synthesis and Applications of Photoluminescent Carbon Nanodots." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/00744008479588662690.
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碩士國立臺灣大學
化學研究所
100
This study aims to develop an environmentally benign method for the preparation of multifunctional carbon dots (C-dots). In chapter one, We have discussed a green synthetic approach for the preparation of photoluminescent C-dots from used coffee grounds. This is the first example of the large-scale hydrothermal synthesis of C-dots from used coffee grounds, which demonstrated two analytical applications [cell imaging and surface-assisted laser desorption/ionization-mass spectrometry (SALDI-MS)] showing its great practical potential. In chapter two, a highly water-soluble benign approach for the preparation of multifunctional C-dots from used green tea have been demonstrated. The inhibitory activity of C-dots is likely to be associated with catechins and their derivatives on the surfaces of C-dots. Unlike most of the C-dots preparation methods reported in the literature, the C-dots prepared from used green tea are highly effective and selective inhibitors for breast cancer cells (MCF-7 and MDA-MB-231), offering high practical potential for use in bioanalysis and medicine. In chapter three, a simple one-pot hydrothermal approach has been demonstrated for the preparation of highly water soluble and photoluminescent C-dots. We found that the compounds having amino and carboxylic acid groups are suitable for the preparation of high quantum yield C-dots (QY = 30.6 %). Therefore, this study not only revealed the development of simplified and convenient synthesis of C-dots, but also demonstrated large-scale preparation of high quantum yield C-dots. In addition, the as-prepared C-dots showed their great practical potentiality, which opens up further bioanalytical applications.
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Liao, Wei-Cheng, and 廖偉程. "Manipulation of Random Lasers Assisted by Plasmonic Carbon Nanodots." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/xv7aa5.
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碩士國立臺灣大學
物理學研究所
105
Carbon nanodots emerge as popular materials in various research fields, including biological and photovoltaic areas, while there lacks significant reports related to their applications in laser devices, which play a significant role in our daily life. In this work, we demonstrate the first controllable random laser assisted by the surface plasmon effect of carbon nanodots. Briefly, carbon nanodots derived from candle soot are randomly deposited on the surface of gallium nitride (GaN) nanorods to enhance the ultraviolet fluorescence of GaN and generate plasmonically enhanced random laser action with coherent feedback. Furthermore, potentially useful functionalities of tunable lasing threshold and controllable optical modes are achieved by adjusting the numbers of carbon nanodots, enabling for optical communication and identification technologies. In addition to providing an efficient alternative for plasmonically enahnced random laser devices with simple fabrication and low cost, our work also paves a useful route for the application of environmentally friendly carbon nanodots in optoelectronic devices.
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羅文鍵. "Enhancement of the Quantum Yield of Hydrothermally Synthesized Carbon Nanodots." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/r33r7h.
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碩士逢甲大學
化學工程學系
102
This study prepared carbon nanodots (CNDs) by the hydrothermal method using precursors such as L-glutamine, L-glutamic acid, L-ascorbic acid, and egg white. The solvent was deionized water. It is expected to enhance the quantum yield (QY) of the hydrothermal product by adding in different additives in the hydrothermal process. The synthesized CNDs were analyzed using the laser particle sizer, UV-Vis spectrometer, and fluorescence spectrometer. The results showed that the CNDs were all less than 100 nm in diameter, that they emitted purple light between 380 nm and 450 nm under the irradiation of 300 nm ultraviolet light, that the QY of the samples from L-glutamic acid might pass over 10%, and that some additives could raise the QY of the CNDs by an order of magnitude.
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Yang, Chiachen, and 楊佳珍. "Investigation of titania nanorod/carbon nanotube composite photocatalysts." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/84117739439463561205.
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碩士東海大學
環境科學與工程學系
99
In the present study, a microwave-assisted hydrothermal method was used to prepare titanium nonorods (TNRs) and TNR/multi-wall carbon nanotube （TNR/MWCNT） photocatalysts in relatively short time. The composites were characterized by Multi-Function Scanning Electron Microscope （SEM）、Transmission Electron Microsopy（TEM）、X-ray Powder Diffractometer（XRD）、BET surface area、Diffuse Reflectance UV-visible Spectrophotometer（UV-Vis spectrophotometer）、X-ray Photoelectron Spectroscopy（XPS）、X-ray Absorption Spectroscope（XAS）and their photocatalytic activities were tested by photo degradation of methyl blue in water. SEM and TEM micrographs indicated that TNRs had a length of approximately 300 nm with a diameter of about 30 nm and were non-hollowed. XPS spectra strongly indicated the existence of Ti－C bond; TNRs exited in anatase and rutile forms as shown by the results from both XRD and XAS. The BET surface area of the TNRs were 53~ 197 m2/g. TNRs showed a red-shift in UV-Vis absorption that increased with greater MWCNT addition.Under UV light illumination for 3 hours, the greatest photocatalytic activity was observed for the composite catalyst with C/Ti mole ratio of 1：1.
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Chang, Che-Yuan, and 張哲元. "Effect of Chain Length of Dicarboxylic Acids on Photoluminescence of Green Carbon Nanodots." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/75415535431216376675.
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碩士中山醫學大學
應用化學系碩士班
103
This research is to investigate the relation between the length of carbon chain as carbon source and quantum yield (QY), and how to obtain the maximum QY using a green and simple method - hydrothermal synthesis, to produce series of fluorescent carbon dots (CDs). To carry out the experiment, five variations of dicarboxylic acids with different length of carbon chain as carbon source are used. They are then doped with different proportions of ethylenediamine(EDA) which acts as a representative surface passivation agent, and with magnesium hydroxide (Mg(OH)2) as a representative chelation agent to enhance the QY. After the research, the most suitable synthesis proportion to enhance the QY is discovered, and the relation between QY and length of carbon chain as carbon source is also understood. As a result, highest value of QY (31.50%) was achieved. In green chemistry, the solvent used in reactions to synthesize CDs was ultrapure water which makes the CDs totally soluble in water. More than that, CDs need only to be filtered by 0.22 μm filter and no any additional treatment will be needed. The aqueous solution of the CDs was light yellow when observed under visible light and emitted blue fluorescence if irradiated by ultraviolet light. All the CDs in experiments were measured by the UV-Vis spectrometer for their absorbance, fluorescence spectrometer was used to record their properties of photoluminescence and FTIR was used to appraise the chemical functional groups. All the samples are stored at room temperature for almost six months and they still retain their fluorescence intensity. The long duration of fluorescence intensity shows its potential for broad application. Furthermore, we used carbon dots and 5-fluorouracil (5-FU) under ultrasonic oscillation. The CDs produced in this research could be used as a drug carrier or bio-imaging marker.
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林明翰. "Effects of Sulfuric Acid on Quantum Yield of Hydrothermally Synthesized Fluorescent Carbon Nanodots." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/18348610745125003077.
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碩士逢甲大學
化學工程學系
104
Since the discovery in 2004, fluorescent carbon nanodots (FCNDs) have received wide attention due to their excellent biocompatibility and fluorescence. The fluorescent property enables FCNDs to be applied to bioimaging, biosensing, and photocatalysis. To effectively increase the quantum yield (QY) of FCNDs has been an issue of study. The hydrothermal method is widely used to synthesize FCNDs because of simple operation among other methods such as laser ablation and microwave heating. The basic principle of the hydrothermal method is to put the precursor of carbon dots with additives in water and under high temperature and pressure to induce multiple chemical reactions such as carbonization and polymerization. In this study we prepared high QY FCNDs by the hydrothermal method with sulfuric acid as an additive which promotes carbonization. Through the UV absorbance and fluorescence intensity obtained from the UV-Vis and fluorescence spectra, the QY of FCNDs can be calculated. Results show that QY can be increased by 50–100% by adding a small amount of sulfuric acid. The preferred case in this study is that the highest QY (17.6%) can be reached by adding 0.03 ml sulfuric acid to the HEDTA solution. In addition, result of dynamic light scattering analysis and atomic force microscope imaging, the aforementioned FCNDs has an average particle diameter of 8.47 nm.
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Lin, Yaling, and 林雅玲. "Electrochemical Preparation of Photoluminescent Carbon Nanodots and Their Application as Copper Ions Sensor." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/8twenm.
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碩士國立臺灣大學
化學研究所
106
We used a simple, fast, eco-friendly electrochemical strategy to prepare carbon nanodots (C dots) from histidine under alkaline conditions by applying a constant voltage of 10 V at room temperature without using any toxic chemicals and organic solvents. The effects of concentrations of histidine, pH, reaction time and sodium halides such as sodium chloride (NaCl), sodium bromide (NaBr), and sodium iodide (NaI) on the properties of as-prepared C dots were investigated. The optimal conditions to prepare C dots are 0.63 M histidine, pH 9.0 and 1 M sodium halides. This method has the advantages of low-cost, short reaction time, low energy and the photoluminescence (PL) is observable at any time. The formation rates of C dots synthesized by adding NaCl, NaBr and NaI (Cl-C dots, Br-C dots, I-C dots) was controlled through the differential nucleophilicity and leaving ability of sodium halides. The C dots prepared in presence of sodium halides exhibits high photostability at high concentrations of salts (0-3.0 M), different pH (3.0-11.0) and 1 h irradiation. Compared to C dots, Cl- or Br-C dots, I-C dots shows high selectivity and sensitivity toward the Cu2+ ions. Cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) results confirmed the formation of metal-ligand complexes between Cu2+ ions and I-C-dots and the charge transfer leading to the PL quenching of I-C dots. The I-C dots allowed detection of Cu2+ ions, with a limit of detection (LOD) and a linear range of 0.22 μM and 0.3-3.0 μM, respectively. Furthermore, the practicality of I-C dots toward the detection of Cu2+ ions in real samples such as tap water, lake water and seawater was demonstrated. Having advantages such as short preparation time, high photostability, high selectivity and sensitivity, I-C dots are holding great potential for the detection of Cu2+ ions in complex matrices such as living cells and blood.
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Tsai, Tsung-Tang, and 蔡宗唐. "Characteristics of carbon nanotube and ZnO nanorod field effect transistors." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/27065566981456303466.
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碩士國立中興大學
物理學系所
98
In this thesis, we fabricated multi-wall carbon nanotube and ZnO nanorods field effect transistors(FETs) with electron beam lithography. The FETs we make are kinds of measurements, we found out the multi-wall carbon nanotube field effect transistors are P-type FETs. The threshold voltage is around -1V. and the on-off ratio is around 3.10. We also measured the electrical properties of multi-wall carbon nanotubes. The current is exponential growing with voltage. Detailed measurements indicates that the junction of gold and carbon nanotubes is Schottky contact. The MWCNT FETs has diode like behavior, which shows that the nature of multi-wall carbon nanotubes is semiconductor. Moreover the diode reverse saturation current is measured around 0.5nA. In addition, with four point measurements, the resistance of metallic MWCNTs FETs is determined to be . We also produce the ZnO nanorods by VLS method, scanning electron microscope、transmission electron microscope、X-Ray Diffraction、Energy dispersive spectrometer are used to determined the characteristics of ZnO nanorods. The rods show the growth along (002) direction. Finally we fabricated the ZnO-FETs.
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Yueh, Yao-Pin, and 岳耀彬. "Carbon Nanodots-based Electrochemical Immunosensor For Label Free Hepatoma- Derived Growth Factor (HDGF) Detection." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/335w52.
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碩士義守大學
生物技術與化學工程研究所
102
Hepatoma-derived growth factor (HDGF), originally isolated from the cultured media of human hepatoma HuH-7 cells, stimulate the growth of fibroblast cells, endothelial cells, and hepatoma cells. Overexpression of HDGF has been proved to be related to the transformation of human hepatoma, lung cancer and melanoma. However, the measurement of HDGF is still a tedious and challenging task. Herein, a disposable, label-free electrochemical immunosensor based on carbon nanodot /chitosan nanocomposite modified screen-printed electrode was developed for the detection of HDGF. Carbon nanodots (CNDs) were prepared under microwave radiation, using glucose and oligochitosan as reactants. The as-prepared CNDs were facially mixed with chitosan to form a CND/CS nanocomposite. The use of CNDs increased the stability and sensitivity of the sensor, while the amino groups on chitosan worked as binding sites for the bioconjugation of anti-HDGF. Amperometric responses were obtained by differential pulse voltammetry (DPV) in presence of a ferrocyanide/ferricyanide redox pair after HDGF incubation. The DPV response of the immunosensor increased with the increasing concentration of HDGF detected. The calibration curve showed a good linear relationship between the peak current and logarithm values of the analyte concentration in the range from 1 pg/mL to 70 ng/mL, with a good correlation coefficient (R2 = 0.988, RSD<4%, n=5). The resulting immunosensor displays a wide range of linear response, good reproducibility and stability with a very cost effective way, indicating its promising potential for clinical immunoassays.
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Chang, Hsin-Yueh, and 張心悅. "Application and characteristics of carbon nanorod synthesized by radio frequency magnetron sputtering." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/41874671361931766174.
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博士國立臺灣科技大學
電子工程系
103
We present a method for growing carbon nano rods (CNR), an allotrope of 1-D carbon, using radio frequency magnetron sputtering at low temperature. We first investigate how the growth temperature (from room temperature to 380℃) and sputtering gas (Ar and N2) influence the CNR morphology and structure. The resulting CNRs were observed to be aligned vertically onto the substrate with uniform length exhibiting an amorphous structure with semiconducting properties. The CNR morphology did not change obviously but the crystallinity was enhanced with an increase in the growth temperature. Moreover, different CNR morphologies were observed when synthesized using various Ar/N2 sputtering gas ratios. Film-like CNRs were formed when pure N2 (or Ar) was used as the sputtering gas. Rod-like CNRs were formed when mixed Ar and N2 sputtering gas was applied. These inconsistent results indicate that sputtered carbon particles of different sizes and energy can be ascribed to the CNR formation. CNRs doped with different nitrogen content was used as the cathode catalysts for the proton exchange membrane fuel cell (PEMFC). The catalytic activity toward the oxygen reduction reaction (ORR) was studied. The nitrogen content was controlled directly by adjusting the Ar/N2 ratio during CNR growth. The nitrogen content and C–N bonding configuration of the samples were characterized using X-ray photoelectron spectroscopy, which demonstrated that the nitrogen content can reach up to 31.87% and the pyridinic-type nitrogen content increased with the increase in nitrogen content. The nitrogen-doped CNR with the largest amount of pyridinic-type nitrogen configuration exhibits superior ORR activity, which leads to a four-electron transfer in alkaline solution. The reduction current density can reach up to -7.8 mA/cm2, which opens the possibility for metal-free PEMFC catalysts applications. On the other hand, a hybrid 3-D structure, CNRs/graphene, was fabricated by combining highly conductive graphene (2-D) with vertically aligned CNRs (1-D). We used CNRs as the electrode and graphene as the current collector for electric double layer capacitor (EDLC) applications. The CNR and graphene combination has the following advantages: (1) The C–C bonding of the interface can effectively lower the impedance; (2) The structure can enhance the electron transmission speed in the device. The synthesized CNRs on graphene presented high number density, high direct aspect and large surface area, which can increase the reactive surface area between the electrode and electrolyte. The capacitor performance was characterized using cyclic voltammetry and galvanostatic charge-discharge testing in 1 M KOH electrolyte at 30℃, 40℃, 50℃, and 60℃. The CNR specific capacitance was observed to increase with increasing measurement temperature and could reach up to 830 F/g at 60℃. Even after extensive measurements, the CNR electrode maintained good adhesion to the graphene current collector, thereby suggesting electrode material stability.
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Lin, Chia-Wei, and 林嘉偉. "The Study of Hyaluronic Acid Conjugated Carbon Nanodots as a Tracking Label for Mesenchymal Stem Cells." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/utn956.
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碩士中原大學
生物醫學工程研究所
105
Cell tracking labels with excellent biocompatibility, ease of use, resistance to photobleach and long-lasting efficiency are needed. Carbon nanodots (CDs) have high water solubility, low toxicity, photostability and fluorescent property which can be used in the areas of biosensing, bioimaging, light emitting device and drug carrier. In this study, carbon dots low molecules (CD-Ls) and carbon dots high molecules (CD-Hs) were synthesized by low molecular weight and high molecular weight polyethyleneimine (PEI) by microwave assisted pyrolysis. Furthermore, CD-Ls and CD-Hs were conjugated with hyaluronic acid (HA) form CD-L-HAs and CD-H-HAs. CDs were discovered they can emit blue fluorescence by UV light excitation, the particle size less than 10 nm according Atomic force microscopy and had positive zeta potential. In vitro assay revealed that CD-Ls and CD-L-HAs had no cytotoxicity against human bone marrow mesenchymal stem cells (MSCs). But 30 μg/ml of CD-Hs and 50 μg/ml of CD-H-HAs had significant cytotoxicity against MSCs. NIH3T3 cells which is negative control of MSCs cultured with CD-L-HAs or CD-H-HAs respectively had high cell viability. In cell uptake assay that MSCs had blue fluorescence. But NIH3T3 cells had not any fluorescence. In cell uptake of CDs’s fluorescence had no significant difference. The results of non invasion in vivo imaging system (IVIS) showed CDs’s fluorescence was observed at 0 hours. And CD-Ls still had blue fluorescence after 24 hours. Here, we provide the possibility of applying CDs as a label to tracking MSCs migration after systemic infusion into animals.
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Chen, Po-Lin, and 陳柏林. "Anodic aluminum oxide template assisted growth and electron field emission of carbon nanotubes and titanium oxide nanodots." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/03139024654847640948.
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博士國立交通大學
材料科學與工程系所
93
Ordered arrays of carbon nanotubes (CNTs) and titanium oxide (TiO2) nanodots have been successfully prepared by using the nanoporous anodic aluminum oxide (AAO) films as templates. Nanoporous AAO templates with hexagonal pore arrangement were prepared by the two-step anodization of aluminum films. Highly aligned CNTs were grown in vertical channels of the AAO template by microwave plasma electron cyclotron resonance chemical vapor deposition (ECR-CVD). The segments of CNTs stretching out of the AAO nanopores still maintain relatively good alignment, and have a very slow growth rate, which allows us to obtain reproducible tube length by tuning the growth time. Field emission measurements of the CNTs showed good electron emission properties, attributed to their uniformity in size, good alignment, and good graphitization properties. We have also demonstrated that the tube number density of aligned CNTs grown over the AAO template can be directly controlled by adjusting the CH4:H2 feed ratio during the CNT growth. We ascribe the variation of the tube density as a function of the CH4:H2 feed ratio to the kinetic competition between outgrowth of CNTs from the AAO pore bottom and deposition of the amorphous carbon overlayer on the AAO template. A pore-filling ratio of 18 to 82% for the nanotubes overgrown out of nanopores on the AAO template can be easily achieved by adjusting the CH4:H2 feed ratio. Enhanced field emission properties of CNTs were obtained by lowering the tube density on AAO. However, at a high CH4 concentration, amorphous carbon byproduct deposit on the CNT surface can degrade the field emission property due to a high energy barrier and significant potential drop at the emission site. Highly ordered nanodot arrays of TiO2 were prepared from Al/TiN films on the silicon substrate by electrochemical anodization of a TiN layer using a nanoporous AAO film as the template. The arrangement and shape of the nanodots are in accordance with the nanopores of the AAO template. The size of the nanodots can be varied over a wide range (ten to several hundred nanometers) because the diameter of the AAO nanopores is dependent upon anodization parameters. The size uniformity and surface smoothness of the TiO2 nanodots can be further improved by anodization of an epitaxial Al/TiN film stack on a sapphire substrate. The phase development of the isolated TiO2 nanodots is very much different from TiO2 thin films and powders. After high temperature annealing, the nanodots are polycrystalline and consist of a mixed phase of anatase and rutile instead of single rutile phase. We conclude that TiO2 nanodots with a single phase of anatase can be realized as long as the size of the nanodots is smaller than the critical nuclei size for rutile formation. Using this novel approach, it is expected that nanodot arrays of various oxide semiconductors can be achieved. Furthermore, a field emission triode device using the self-organized nanodot arrays as electron emission source was proposed and fabricated. The field emission triodes with nanodot emitters exhibited a low gate turn-on voltage of 45 V and high emission current density of 25 mA/cm2 at 120 V. The desirable electric properties and easily controllable fabrication process of the nanodot triodes show potential for application in field emission displays (FEDs) and vacuum microelectronics.
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Hsu, Chan-Wei, and 許展瑋. "Sandwiched Nanostructure of Hydrogenated Carbon Doped TiO2 Nanoparticle/Nitrogen Doped Carbon/Rutile TiO2 Nanorod Array for Efficient Photoelectrochemical Water Oxidation." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/s93xy3.
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Weng, Yu-Hsuan, and 翁于軒. "Fabrication of Highly Efficient Piezoelectric ZnO Nanorod Arrays by Using Conducting Polymer/Carbon Nanotube Hybrid substrates." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/wnnb4z.
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碩士國立臺北科技大學
有機高分子研究所
101
In this study, ZnO nanorods have been synthesized via wet chemical method on PEDOT/MWNTs polymer nanocomposite materials. The study is divided into three parts. First, PEDOT conductive film was prepared by the method of “In situ oxidative polymerization”. The effect of conductivity of different acid-treated carbon nanotubes in the PEDOT film was investigated. Second, we use alkalis to react with zinc acetate to prepare nanoscale ZnO particles in solution, which were spin coated on the substrate several times so that it can be covered with ZnO seed layers. Finally, we prepared ZnO nanorods by using hydrothermal method on PEDOT film precoated with ZnO seed layers. The effects of substrates on the morphology and piezoelectricity of PEDOT / ZnO composite films were discussed. On the substrates pre-seeded by ZnO seed solution with good wurtzite structure and preferred orientation along the (002) direction (c-axis), which ZnO nanorods can be vertically oriented with respect to the substrate as hexagonal pillars. Finally, we use OM to observed the dispersion of carbon nanotubes in PEDOT film. The crystal structure of ZnO was identified by XRD. The surface morphology of the composite material and piezoelectric properties was observed by SEM and AFM.
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Tseng, Tzu-chieh, and 曾子杰. "Fabrication and study of single-walled Carbon Nanotubes Nanonet Based Organic Heterojunction Thin Film Solar Cell." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/48365643070833685555.
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碩士國立成功大學
航空太空工程學系碩博士班
97
Carbon nanotube, a kind of different Carbon allotrope, with unique mechanical and electrical science identities, is the core that many researches focus on. Between different nano devices, carbon nanotube has outstanding potency. Organic solar energy cells possess many advantages: flexibility, low-cost, and easy processing technologies and so on, has distinctive position in solar energy cells. This research using Alcohol Catalytic Chemical Vapor Deposition to develop growth of single-wall carbon nanotube and combine with organic polymer thin film, to produce Heterojunction Solar Cell that contains nano structure. Based on the reveal, which showed that the carbon nanotube in this study is single wall carbon nanotube, whose Semiconductor is bi-polar, and is active layer in organic solar cell. Making e the elements to proceed series Electrical property and optics, the study showed that conversion efficiency is 0.012%, short-circuit current density (Jsc) is 0.132mA/cm2, open-circuit voltage(Voc) is 0,23V, and Fill Factor(FF) is 0.39. The compactness of carbon nanotube will affect the Efficiency of cell. Besides, it’s the study for the process of Alcohol Catalytic Chemical Vapor Deposition growing single wall carbon nanotube, put NH3 in to carry out Surface modification of carbon nanotube, observing the varietion of Morphology and optics, to produce solar energy cell; and further, probe into the alterations of electrical propert
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TSAI, SHIN-CHIEH, and 蔡信傑. "Influence of Carbon Nanotube or Graphene Layers on The Characteristics of ZnO Nanorod-based Hydrogen Sensors." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/65359070220778821940.
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碩士國立暨南國際大學
應用材料及光電工程學系
105
In this thesis, ZnO nanorods (NRs) were grown on SiO2 substrates by sol-gel/hydrothermal methods to form hydrogen gas sensing chips. To improve the hydrogen sensing capabilities, a layer of carbon nanotube (CNT) or a layer of graphene layer were sandwiched between the ZnO NRs and the SiO2 substrate, respectively. To characterize the ZnO NRs deposited in various conditions, multiple material analyses including field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD), photoluminescence (PL), transmission electron microscope (TEM) and electron spectroscopy for chemical analysis (ESCA) were used to analyze the material properties. Results indicate that ZnO NRs incorporating CNT on top of the substrate could enhance carrier conduction near the interface and improve the sensing performance. Owing to low cost and simple fabrication, ZnO/CNT/SiO2-based hydrogen gas sensors are promising for future industrial hydrogen gas detection.
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Hsu, Chia-Chi, and 許嘉琦. "Amorphous Carbon Nanotubes and Porous ZnO/C Core-shell Nanorod Arrays：novel preparation and applications in photo-sensing devices." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/29975653911460040264.
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碩士國立高雄大學
化學工程及材料工程學系碩士班
98
Well-aligned amorphous carbon nanotube (a-CNT) arrays were fabricated for the first time by a proposed deposition-etching-evaporation (D.E.E.) route. The a-CNT arrays were prepared by deposition of carbon on the surface of well-aligned ZnO nanorod (NR) arrays by thermal decomposition of acetone followed by spontaneous etching and evaporation of core-ZnO. By utilizing the decomposition of acetone as well as distinct degrees of interaction between intermediate products and ZnO, well-aligned nonporous ZnO/C core-shell NR, porous ZnO/C core-shell NR, and a-CNT arrays were separately prepared by varying the working temperature from 400 to 700℃. Scanning electron microscopy and high-resolution transmission electron microscopy show the thickness of carbon shells increases from 3 to 12 nm with the increase in working temperature. Raman spectra demonstrate slight sp2 bonds of carbon, indicating small graphite regions embedded in amorphous carbon. Photoresponse measurements of ZnO/C NR arrays shows enhancement of both photoresponsivity and response velocity, and the interference of humidity with regard to photo-sensing is effectively reduced by the capping of carbon nanoshells. The work not only provides an effective route to improve the photo-sensing of semiconductor nanomaterials for practical applications, but also sheds light on preparing various hollow carbon nanostructures with distinct morphologies by employing the routes presented in the paper on diverse ZnO nanostructures for opto-electrochemical applications.
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Ghosh, Siddharth. "Nanoscale Photonics." Doctoral thesis, 2016. http://hdl.handle.net/11858/00-1735-0000-0023-3ED4-2.
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