Дисертації з теми "MoS2 Nanoparticles"
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Spence, D'Anne Emmett. "Intercalated MoS2 nanoparticles for enhanced dispersion in smokes and obscurants." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/56.
Повний текст джерелаThesis research directed by: Dept. of Chemistry and Biochemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
James, Derak J. "Synthesis and photocatalytic activity of the MoS2 and WS2 nanoparticles in degradation of organic compounds." CardinalScholar 1.0, 2009. http://liblink.bsu.edu/uhtbin/catkey/1503981.
Повний текст джерелаSynthesis of the sulfide photocatalysts -- Characterization of synthesized nanoparticles -- Photocatalytic degradation tests : setup and protocols -- Photocatalytic degradation tests : results.
Department of Chemistry
Deshpande, Pushkar. "Interaction of MoDTC additive on TiO2 APS coating under mixed/ boundary lubrication conditions : A tribocatalytic process." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC059/document.
Повний текст джерелаNowadays to reduce friction and wear as well as gas emission and oil consumption of the passenger car engines, Atmospheric Plasma Spray (APS) coatings are used on cylinder liner. MoDTC (Molybdenum Di-Thiocarbamate), organometallic friction modifier has been previously used to reduce friction by formation of layered molybdenum disulphide flakes. This study focuses on tribochemical interaction of MoDTC with TiO2 APS coating under mixed / boundary lubrication conditions. Fused and crushed micron sized powders were used to obtain a 70 µm thick TiO2 coating. Various tribometers were used to carry out tribotests in presence of lubricant containing MoDTC. Steel / TiO2 APS contact showed significant friction reduction than steel / reference steel contact. It was shown that the tribofilm is composed of MoS2 and MoO3 on TiO2 APS flats while it is composed of Mo-oxysulphide, MoS2 and MoO3 on reference steel flats. It was shown that wear resistant Magneli phases are formed on the surface of TiO2 APS disc, decreasing wear when the contact was lubricated only with base oil. Impact of various parameters like roughness, test temperature, contact pressure, concentration of MoDTC and change of counterpart materials from steel balls to ceramic balls, on the tribological behavior of TiO2 APS was also studied. Results obtained were compared with contacts involving reference steel and it was confirmed that friction coefficient was always lower in case of contacts involving TiO2 APS coating. Similar tribological results and chemistry were obtained for TiO2 nanoparticles blended with MoDTC in case of steel / reference steel contact. Both the cases, TiO2 APS and TiO2 nanoparticles showed complete decomposition of MoDTC to form MoS2. Tribocatalysis was suggested as the mechanism responsible for complete decomposition of MoDTC in case of TiO2 based materials like TiO2 APS coating and TiO2 nanoparticles
Wery, Madeleine. "Synthèse de catalyseurs de type coeur@coquille pour le procédé d’hydrodésulfuration en phase gazeuse." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAF036.
Повний текст джерелаIn hydrodesulfurization of fossil fuels, the sulfur levels are reduced by sulfur extraction from hydrocarbons by using supported catalysts (MoS2), doped (Co, Ni). Ultra-deep hydrodesulfurization will be achieved by improving new catalysts. Nanoparticles are a promising candidate with their high S/V ratio and permit to use the precise amount of metallic sulphide. The aim of this thesis is the synthesis of core@shell nanometric catalyst with improved activities. Core composed of Fe3O4 or nanodiamonds will be surrounded by a shell formed of MoS2, NiMoS, CoMoS or NiCoMoS, supported on TiO2, γ-Al2O3. Model reaction (thiophene) has allowed to compare conversion rates between each catalyst. Additionally, characterizations have provided a better understanding of the HDS catalyst structure and performances. Some factors have been investigated such as the size of the core, theinteractions between the core and the shell, the type of synthesis, the support chosen, the synergetic effect with doping ions and also the activation of the catalyst at low temperature
Fraga, André Luis Silveira. "Nanoestruturas de Dissulfeto de Molibdênio : síntese e caracterização para produção de hidrogênio." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/180646.
Повний текст джерелаIn this work the synthesis and characterization of MoS2 nanostructures and MoS2 nanostructures decorated with gold nanoparticles is presented. The materials were obtained by hydrothermal route at 200 °C during synthesis periods of 2, 6, 12 and 24 hours. Sodium molybdate was used as Molybdenium precursor and 3-mercaptopropionic acid, cysteamine and L-cysteine as sulfur precursors. To evaluate the effect of ligands on the structures, the MoS2 samples were thermally treated at 250, 550 and 750 °C under argon atmosphere. The effect of gold nanoparticles on the photocatalytic properties of the material was evaluated by obtaining and materials with gold nanoparticle adhered to the MoS2 structures. The materials were characterized by X-ray diffraction (XRD) techniques, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and ultraviolet and visible spectroscopy (UV-Vis). The surface areas and amount of pores were evaluated using BET (Brunauer, Emmett and Teller) and DFT (density functional theory) techniques. The precursor 3-mercaptopropionic acid resulted in the formation of nano-foil agglomerates of about 500 nm in diameter. On the other hand, when using cysteamine and L-cysteine, flower-shaped nanostructures of about 300 nm in diameter formed by petals of about 30 nm were obtained. An interesting result was the rapid formation of nanoflores in the presence of L-cysteine. Nanoflower structures showed hydrogen production up to 9.6 mmol / gh.
Rahneshin, Vahid. "Versatile High Performance Photomechanical Actuators Based on Two-dimensional Nanomaterials." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-dissertations/549.
Повний текст джерелаBouet, Louis. "Valley dynamics and excitonic properties in monolayer transition metal dichalcogenides." Thesis, Toulouse, INSA, 2015. http://www.theses.fr/2015ISAT0033/document.
Повний текст джерелаThe possibility of isolating transition metal dichalcogenide monolayers by simple experimental means has been demonstrated in 2005, by the same technique used for graphene. This has sparked extremely diverse and active research by material scientists, physicists and chemists on these perfectly two-dimensional (2D) materials. Their physical properties inmonolayer formare appealing both fromthe point of view of fundamental science and for potential applications. Transition metal dichalcogenidemonolayers such asMoS2 have a direct optical bandgap in the visible and show strong absorption of the order of 10% per monolayer. For transistors based on single atomic layers, the presence of a gap allows to obtain high on/off ratios.In addition to potential applications in electronics and opto-electronics these 2D materials allow manipulating a new degree of freedom of electrons, in addition to the spin and the charge : Inversion symmetry breaking in addition to the strong spin-orbit coupling result in very original optical selection rules. The direct bandgap is situated at two non-equivalent valleys in k-space, K+ and K−. Using a specific laser polarization, carriers can be initialized either in the K+ or K− valley, allowing manipulating the valley index of the electronic states. This opens up an emerging research field termed "valleytronics". The present manuscript contains a set of experiments allowing understanding and characterizing the optoelectronic properties of these new materials. The first chapter is dedicated to the presentation of the scientific context. The original optical and electronic properties of monolayer transition metal dichalcogenides are demonstrated using a simple theoreticalmodel. The second chapter presents details of the samples and the experimental setup. Chapters 3 to 6 present details of the experiments carried out and the results obtained. We verify experimentally the optical selection rules. We identify the different emission peaks in the monolayer materials MoS2, WSe2 and MoSe2. In time resolved photoluminescence measurements we study the dynamics of photo-generated carriersand their polarization. An important part of this study is dedicated to experimental investigations of the properties of excitons, Coulomb bound electron-hole pairs. In the final experimental chapter, magneto-Photoluminescence allows us to probe the electronic band structure and to lift the valley degeneracy
Sayed-Ahmad, Baraza Yuman. "Theoretical and experimental studies of structure and functionalization of 2D nanomaterials." Thesis, Nantes, 2019. http://www.theses.fr/2019NANT4016/document.
Повний текст джерелаIn this thesis, ab initio DFT methods and complementary experimental techniques are used to study 2D materials. The manuscript focuses on our studies on the polymorphism, edges and functionalization of the 2D-material MoS2. Additionally, we show that functionalization with similar species can be extended to other 2D materials by including studies on the functionalization of graphene. We have studied using DFT calculations the relative stability of different MoS2 polymorphs and associated edge reconstructions, and have proposed qualitative models for understanding the stability trends. Functionalization of MoS2 by covalent and non-covalent strategies is also explored in collaboration with experimental partners. In particular, our calculations indicate that MoS2 can be covalently functionalized, preferentially at edges, leading to a final stable hybrid. This strategy is used to functionalize MoS2 with a photoactive pyrene group that shows significant interaction with MoS2. Experimental results obtained by our collaborators are consistent with our theoretical findings, and an interaction between the photoexcited pyrene moiety and MoS2 is found. A similar interaction is found for direct noncovalent functionalization of the basal plane of MoS2 both theoretically and experimentally. Finally, we show that pyrene derivatives can also be used for functionalizing graphenerelated materials for energy storage applications
Mrzel, A., A. Kovic, A. Jesih, and M. Vilfan. "Decoration of MoSI Nanowires with Platinum Nanoparticles and Transformation into Molybdenum-nanowire Nased Networks." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35168.
Повний текст джерелаJames, Derak J. "Synthesis and photocatalytic activity of the MoS₂ and WS₂ nanoparticles in degradation of organic compounds." Muncie, Ind. : Ball State University, 2009. http://cardinalscholar.bsu.edu/653.
Повний текст джерелаGALLEZOT-TARRET, MAUD. "Preparation et caracterisation de suspensions aqueuses de nanoparticules de mos 2 par chimie douce." Paris 6, 2001. http://www.theses.fr/2001PA066099.
Повний текст джерелаGilstrap, Richard Allen Jr. "A colloidal nanoparticle form of indium tin oxide: system development and characterization." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/33995.
Повний текст джерелаRabaso, Pierre. "Nanoparticle-doped lubricants : Potential of Inorganic Fullerene-like (IF-) molybdenum disulfide for automotive applications." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0103/document.
Повний текст джерелаThe growing environmental concerns, along with the continuous increase in the price of fossil fuels, have highly motivated car manufacturers worldwide to improve the efficiency of their vehicles. The tribological properties of engine and gearbox lubricants have a significant impact on the global efficiency of vehicles, as they contribute to reducing friction in many contacts and allow the downsizing of various components by providing their surfaces with anti-wear protection. The recent breakthroughs in nanoparticle synthesis have opened new prospects in terms of lubricant additivation, with the discovery of the excellent friction and wear reducing properties of nanoparticles such as Inorganic Fullerene-like (IF-) molybdenum or tungsten disulfides. The tribological potential of IF-MoS2 for automobile applications was investigated in this work. The respective influences of nanoparticle size and structure were first of all studied, revealing that poorly crystalline nanoparticles were more efficient in maintaining low-friction tribofilms on steel substrates in severe boundary lubrication regimes regardless of size (for the range studied). All the nanoparticles tested however showed similar performances when proper oil recirculation was ensured, providing a continuous feeding of the contact in nanoparticles. The IF-MoS2 nanoparticles lost their lubricating abilities when added to fully-formulated lubricants. This behavior was attributed to the presence of dispersants in the oil, which dispersed the nanoparticles effectively but prevented them from forming tribofilms on the rubbing surfaces. The well-dispersed IF-MoS2 were shown to enter the contact and exfoliate, but an excessive adsorption of the dispersants on the released MoS2 platelets and/or the steel surfaces is thought to prevent tribofilm adhesion. A balance between nanoparticle dispersion and tribological performance was then found, by using very low concentrations of dispersants. The behavior of nanoparticle-doped oils in various scenarios related to automobile applications was finally explored. The IF-MoS2 provided significant friction and wear reduction at ambient temperature and in milder rolling/sliding test conditions, for smooth and rough surfaces. The risks related to the presence of nanoparticles in the oil in full-film lubrication regimes were partially lifted, with no significant influence on friction witnessed for all the test conditions considered. The ability of IF-MoS2 nanoparticles to protect steel surfaces from surface-initiated Rolling Contact Fatigue was finally shown
Carrada, Marzia. "Manipulation de nanoparticules de Si elaborées par implantation ionique à basse énergie dans des couches minces de SiO2 pour la fabrication de mémoires MOS non volatiles." Toulouse 3, 2003. http://www.theses.fr/2003TOU30015.
Повний текст джерелаCui, Wenwen. "Ab initio investigation of structural and electronic properties on 1D and 2D nanomaterials." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1111/document.
Повний текст джерелаIn this thesis we mainly use the density functional tight-binding method (DFTB) to investigate the effect of high pressure on carbon nanotubes (CNTs). We start by investigating the collapse behavior of individualized CNTs, either empty or filled with water and carbon dioxide molecules. Then we study the collapse process of bundled few-wall (double, triple wall) carbon nanotubes as the function of pressure combining theoretical and experimental studies. Afterwards, we investigate the electronic and magnetic properties of a monolayer MoS2 on the Ni(111) surface with accounting for van der Waals interactions by the density functional theory (DFT). The manuscript is structured in 7 chapters and the following paragraphs summarize the content by chapter of this document.Chapter 1 is our introduction of this thesis, including the motivation and background of our topic as well as our important findings and results. Chapter 2 introduces the main concepts and definitions of CNTs. Then we describe the electronic properties of CNTs as well graphene as a comparison. Chapter 3 consists of the theoretical framework used for our study. Firstly, a short introduction of Density Functional Theory (DFT) is presented. Next we list two mainly used exchange-correlation functions in DFT, then followed by an overview of van der Waals functions which normal DFT cannot account for. Finally, we briefly introduces the Density Functional Tight-Binding method (DFTB) which we use for our CNTs modeling simulation.In chapter 4, we present simulations of the collapse under hydrostatic pressure of carbon nanotubes containing either water or carbon dioxide. We show that the molecules inside the tube alter the dynamics of the collapse process, providing either mechanical support and increasing the collapse pressure, or reducing mechanical stability. At the same time the nanotube acts as a nanoanvil, and the confinement leads to the nanostructuring of the molecules inside the collapsed tube. In this way, depending on the pressure and on the concentration of water or carbon dioxide inside the nanotube, we observe the formation of 1D molecular chains, 2D nanoribbons, and even molecular single and multi-wall nanotubes. For the perfect empty CNTs, collapse behavior theoretically is barely affected by the PTM environment under high pressure but only mainly is determined by the CNTs diameter. Our simulation using DFTB method gives good agreement both for the d dependence predicted by continuum mechanics models and for the deviation at small d which is at least partly due to the atomistic nature of the carbon nanotubes. In chapter 5, we present a theoretical study of the collapse process of single-, double and triple-wall CNTs as a function of pressure. Our theoretical simulations were performed using DFTB for inner tube diameters ranging from 0.6 nm to 3.3 nm. When the walls are separated by the graphitic distance, we show that the radial collapse pressure, Pc, is mainly determined by the diameter of the innermost tube, din and its value significantly deviates from the usual Pcdin-3 Lévy-Carrier law. A modified expression, Pcdin3= (1- 2/din2) with and numerical parameters is proposed. In chapter 6 we investigate the electronic and magnetic properties of a monolayer of MoS2 deposited on a Ni(111) surface using DFT method. Accounting for van der Waals interactions is found to be essential to stabilize the chemisorbed MoS2 monolayer. The interface is metallic due to Mo d states positioned at the Fermi energy, with a Schottky barrier of 0.3 eV and a high tunneling probability for electrons. Small magnetic moments are induced on Mo and S atoms, while we measure a significant demagnetization of the Ni layer at the interface. Finally the last chapter synthesizes the main results of this work presenting also some perspectives
Das, Debanjan. "New Avenues to Transition Metal-Based Water Splitting Electrocatalysts." Thesis, 2019. https://etd.iisc.ac.in/handle/2005/4399.
Повний текст джерелаLeroy, James B. "Infrared spectroscopic studies of adsorption on MoS2 and WS2 : comparison between nanoparticles and bulk materials." 2011. http://liblink.bsu.edu/uhtbin/catkey/1657733.
Повний текст джерелаDepartment of Chemistry
Lin, Cheng-Wei, and 林政維. "CoO nanoparticles and SnO2/ MoS2 composite confined in tube-like mesoporous carbon as efficient nanocomposite anodes for lithium-ion batteries." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/556wth.
Повний текст джерела國立中央大學
化學學系
106
Transition metal oxides and Transition-metal dichalcogenides as anode materials in lithium ion batteries have attracted tremendous attention because of their high theoretical capacities compared with commercial graphite. However, the large volume expansion during the charge-discharge process leads to low electrical conductivities. In first part, we design a tubular nanocomposite of CoO@CMK-9 to overcome this problem. A three-dimensional (3-D) hollow-type ordered mesoporous carbon (CMK-9) could not only provide enough space during the Li+ insertion-extraction process, but also increase the electrical conductivity. CoO is regarded as one of the most promising anode material for lithium ion batteries (LIBs), due to its high theoretical capacity (715 mAh/g), natural abundance, and low cost. CoO@CMK-9 delivers a reversible capacity of 828 mAh/g after 200 cycles at a current density of 100 mAh/g with an outstanding rate performance. The CoO@CMK-9 nanocomposite is expected to have high specific capacity and good cycling performance. In second part, we design a novel structured SnO2/MoS2@CMK-9, MoS2 is a graphene-like layered structure, Mo is sandwiched between two S layers. The atoms in the layers are bound strongly by covalent bonds, while the adjacent layers interact by weak van der Waals forces. MoS2 nanosheets can be easily restacked together during charge–discharge processes. To solve this problem, we add SnO2 nanoparticles which can avoid to restack of MoS2 nanosheets. SnO2/MoS2@CMK-9 demonstrate an excellent Li-storage performance as an anode of LIBs, deliver a high reversible charge capacity of 782 mAh/g after 50 cycles at a current density of 100 mAh/g.
Zhang, Z., W. Li, M. F. Yuen, T.-W. Ng, Y. Tang, C.-S. Lee, Xianfeng Chen, and W. Zhang. "Hierarchical composite structure of few-layers MoS2 nanosheets supported by vertical graphene on carbon cloth for high-performance hydrogen evolution reaction." 2015. http://hdl.handle.net/10454/9428.
Повний текст джерелаHere we report a hierarchical composite structure composed of few-layers molybdenum disulfide nanosheets supported by vertical graphene on conductive carbon cloth (MDNS/VG/CC) for high-performance electrochemical hydrogen evolution reaction (HER). In the fabrication, 3D vertical graphene is first prepared on carbon cloth by a micro-wave plasma enhanced chemical vapor deposition (MPCVD) and then few-layers MoS2 nanosheets are in-situ synthesized on the surface of the vertical graphene through a simple hydrothermal reaction. This integrated catalyst exhibits an excellent HER electrocatalytic activity including an onset potential of 50 mV, an overpotential at 10 mA cm(-2) (eta(10)) of 78 mV, a Tafel slop of 53 mV dec(-1), and an excellent cycling stability in acid solution. The excellent catalytic performance can be ascribed to the abundant active edges provided by the vertical MoS2 nanosheets, as well as the effective electron transport route provided by the graphene arrays on the conductive substrate. Moreover, the vertical graphene offers robust anchor sites for MoS2 nanosheets and appropriate intervals for electrolyte infiltration. This not only benefits hydrogen convection and release but also avoids the damaging or restacking of catalyst in electrochemical processes.
This work was financially supported by the National Natural Science Foundation of China (Grant nos. 61176007, 51372213, and 51402343).
Praveena, M. "Design, Fabrication and Application of In situ Total Internal Reflection (TIR) Raman Tribometer For the Chemical Analysis of Tribological Systems." Thesis, 2013. https://etd.iisc.ac.in/handle/2005/4581.
Повний текст джерелаChiang, Wen-Cheng, and 江文誠. "A Novel MoS2-Upconversion Nanoparticle Composite for Photodetection." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/bdrknn.
Повний текст джерелаChitara, Basant. "Properties And Applications Of Semiconductor And Layered Nanomaterials." Thesis, 2012. https://etd.iisc.ac.in/handle/2005/2288.
Повний текст джерелаChitara, Basant. "Properties And Applications Of Semiconductor And Layered Nanomaterials." Thesis, 2012. http://hdl.handle.net/2005/2288.
Повний текст джерелаSharma, Devansh. "PDMS-Based Nanocomposite for EMI Shielding application." Thesis, 2022. https://etd.iisc.ac.in/handle/2005/5878.
Повний текст джерелаMomentive Performance Materials PVT. LTD. and CII
CHEN, CHUN-CHE, and 陳俊哲. "Enhancing the Performance of MoS3/Graphene Composite Photocatalyst toward Hydrogen Prodction by Using the Surface Plasmon Resonance Based on the Au@Ag Nanoparticles with Core-shell Structure." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/2br64m.
Повний текст джерела東海大學
化學系
106
Hydrogen is considered a kind of energy fuels of cleanliness and usefulness. Hydrogen burning is the process of water transformation after releasing energy without pollution.Zero carbon emission can be acieved. However, Pt is too scarce and expensive to utilize widely. Therefore, this study is developing low cost and highly efficient catalyst for hydrogen evolution application in photocatalytic decomposition of water. In this project, we successfully synthesized core-shell structure Au@Ag nanoparticles and loaded it with the MoS3/rGO. To form a photocatalytic composite, we chose the ErY as a photosensor which SPR is similar to the core-shell Au@Ag nanoparticles.Because of Surface Plasmon Resonance, photon effects greatly on the surface that improves quantum conversion efficiency and photocatalytic activity. Besides, as the concentration of ammonium tetrathiomolybdate ((NH4)2MoS4 ) increased, the amount of hydrogen production by the MoS3/rGO composite also increased.However, there is non the same phenomenon the amount of the hydrogen production by MoS3/Au@Ag/rGO composite.We might predict that the coverage of gold and silver core-shell nanoparticles reduce the absorption of visible light because of the excessive load concentration of (NH4)2MoS4. When the concentration of (NH4)2MoS4 is 3mM, the amount of hydrogen producs most highly by the MoS3/Au@Ag/rGO , and the MoS3/rGO with the same loading concentration increases 290% of the hydrogen production. We also do a lot of control experiments to verify the role of each material in the composite. To support the consequence, fluorescence spectrometer, single wavelength test and photocurrent experiments are used. We also do the composite long term stability test. Based on the above results, we discussed the photocatalytic hydrogen production mechanism of MoS3/Au@Ag/rGO.