Dissertations / Theses on the topic 'Metal supported nanoparticle'
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Hermans, S. "Mixed-metal clusters as precursors for bimetallic supported nanoparticle catalysts." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603977.
Full textKwon, Beatsam. "Catalytic reduction of organic pollutants using supported metal nanoparticles." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23190/.
Full textMartelli, Francesca. "Supported metal nanoparticles for sustainable green catalytic processes." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20699/.
Full textCrites, Charles-Oneil. "Investigating the Interactions between Free Radicals and Supported Noble Metal Nanoparticles in Oxidation Reactions." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33404.
Full textCelik, Caglar. "Carbon Supported And Surfactant Stabilized Metal Nanoparticle Catalysts For Direct Methanol Fuel Cells." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606368/index.pdf.
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August 2005, 72 pages Carbon supported surfactant, such as 1-decanethiol and octadecanethiol, stabilized platinum and platinum/ruthenium species have been prepared recently. In this thesis, for the first time, 1-hexanethiol has been used as an organic stabilizer for the preparation of carbon supported platinum and platinum/ruthenium nanoparticle catalysts. These new catalysts were employed for methanol oxidation reaction, which were used for direct methanol fuel cells. Cyclic voltammetry, X-ray photoelectron spectroscopy and transmission electron microscopy have been used in order to determine the nature of the catalysts. The effect of temperature and time on catalytic activity of catalysts were examined and the maximum catalytic activity was observed for carbon supported 1-hexanethiol stabilized platinum nanoparticle catalyst (with 1:1 thiol/platinum molar ratio) which was heated up at 200oC for 5 hours. The particle size of platinum nanoparticles was determined to be ~ 10 nm in diameter. The size and distribution of metal nanoparticles on carbon support, the Pt/Ru surface composition, the relative amount of Pt(0), Pt(II) and Pt(IV) and the removal of organic surfactant molecules around the metal nanoparticles were found to be important in determining the catalytic activity of electrodes towards methanol oxidation reaction. A significant decrease in catalytic activity was observed for carbon supported 1-hexanethiol stabilized Pt75Ru25 and Pt97Ru3 (with 1:1 thiol/PtRu molar ratio) with respect to carbon supported 1-hexanethiol stabilized Pt (with 1:1 thiol/platinum molar ratio). This result might be due to unremoved stabilizer shell around platinum/ruthenium nanoparticles and increase in amount of Pt(II) and Pt(IV) compared to Pt(0) where the methanol oxidation occured.
Bruzas, Ian R. "Biocompatible noble metal nanoparticle substrates for bioanalytical and biophysical analysis of protein and lipids." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553250462519941.
Full textNgandjong, Alain Cabrel. "Modélisation structurale des clusters d’alliages supportés : effet du support de silice et effet de taille." Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2070/document.
Full textNumerical simulations have so far neglected the influence of amorphous silica substrate on the structure of metallic nanoparticles due to its relatively weak interaction with deposited nanoparticles. However, experimental studies have often shown a truncation effect on the structure of nanoparticles. The idea of this work was to study the influence of this substrate on the structure of silver nanoparticles using molecular modeling (Monte Carlo and molecular dynamics). The objective of this work was firstly to determine silver-silica interatomic potential. This was achieved using experimental data of wetting angles in solid and liquid phase. On the other hand, silver-silica interaction intensity was determined by DFT calculations on cristobalite which is a polymorph of crystalline silica having the same density as amorphous silica. The adhesions energies obtained were used to fit the Lennard-Jones parameters for the silver-silica interaction. The study of the structural stability of silver nanoparticles supported at zero temperature was performed for three levels of approximation of the support. (1): the smooth wall approximation where the support is described by a square-well whose depth is related to the adhesion energy of the nanoparticle, (2): an atomistic model of flat amorphous silica, (3): an atomistic model of rough amorphous silica. The influence of the temperature on the structure was investigated by melting and recrystallization of the silver nanoparticles deposited on the two silica supports. In order to study the temperature stability of the nanoparticles the free energy calculation of the nanoparticles was discussed
Udumula, Venkata Reddy. "Synthesis, RNA Binding and Antibacterial Studies of 2-DOS Mimetics AND Development of Polymer Supported Nanoparticle Catalysts for Nitroarene and Azide Reduction." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/6031.
Full text杨纯臻 and Chunzhen Yang. "Metal/metal oxide nanoparticles supported on nanostructured carbons for electrochemical applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/193414.
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Bocelli, Ludovica. "Catalytic decomposition of formic acid using supported metal nanoparticles." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11929/.
Full textELAZAB, HANY. "Graphene-Supported Metal Nanoparticles For Applications in Heterogeneous Catalysis." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/560.
Full textLombardi, Erica. "Selective photo-oxidation of cellobiose with tio2-supported metal nanoparticles." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/6017/.
Full textMeduri, Kavita. "Carbon-Supported Transition Metal Nanoparticles for Catalytic and Electromagnetic Applications." Thesis, Portland State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10933285.
Full textRecently, there has been growing interest in using transition metals (TM) for catalytic and electromagnetic applications, due to the ability of TMs to form stable compounds in multiple oxidation states. In this research, the focus has been on the synthesis and characterization of carbon-supported TM nanoparticles (NPs), specifically palladium (Pd) and gold (Au) NPs, for catalytic applications, and transition metal oxides (TMO) NPs, specifically Fe3O4 NPs for electromagnetic applications. Carbon supports have several advantages, such as enabling even distribution of particles, offering large specific surface area with excellent electron conductivity, and relative chemical inertness.
In this dissertation, for catalytic applications, emphasis was on removal of trichloroethylene (TCE) from groundwater. For this application, carbon-supported Pd/Au NP catalysts were developed. Pd was chosen because it is more active, stable and selective for desired end-products, and Au has shown to be a good promotor of Pd’s catalytic activity. Often, commercially available Pd-based catalysts are made using harsh chemicals, which can be harmful to the environment. Here, an environmentally friendly process with aspects of green chemistry was developed to produce carbon-supported Pd/Au NP catalysts. This process uses a combination of sonochemistry and solvothermal syntheses. The carefully designed carbon-supported Pd/Au NP catalyst material was systematically characterized, tested against TCE, and optimized for increased rate of removal of TCE. Electron microscopy and spectroscopy techniques were used to study the material including structure, configuration and oxidative state. The Pd/Au NPs were found mainly to form clusters with an aggregate-PdShellAuCore structure. Using state-of-the-art direct detection with electron energy loss spectroscopy, the Pd NPs were found to have an oxidative state of zero (0). The formation of the catalyst material was studied in detail by varying several synthesis parameters including type of solvent, sonication time, synthesis temperature etc. The most optimized catalyst was found remove TCE at double the rate of corresponding commercial Pd-based catalysts in a hydrogen headspace. This material was found to catalyze the removal of TCE via traditional hydrodehalogenation and shows promise for the removal of other contaminants such as trichloropropane (TCP), carbon tetrachloride (CT).
This green approach to make and optimize TM materials for specific applications was extended to TMOs, specifically magnetite (Fe3O4) and further developed for the application of electromagnetism. As catalysts, Fe3O4 is used for removal of p-nitrophenol from water. However, since the carbon-supported Pd/Au material system was developed and optimized for catalysis, here, carbon-supported Fe3O 4 NPs were developed for electromagnetic applications. There has been growing interest in tuning the magnetic properties of materials at room temperature with the use of external electric fields, for long-term applications in data storage and spintronic devices. While a complete reversible change of material properties has not yet been achieved, some success in partial switching has been achieved using multiferroic spinel structures such as Fe3O 4. These materials experience a change in magnetic moment at room temperature when exposed to the electric fields generated by electrochemical cells such as lithium ion batteries (LIBs) and supercapacitors (SC). In the past, a 1% reversible change was observed in Fe3O4 using LIBs. Here, building on the developments from previous material system, Fe 3O4 NPs were directly hybridized onto the graphene support in order to increase the observable change in magnetic moment. The material was systematically designed and tested for this application, including a study of the material formation. A simple, environmentally friendly synthesis using the solvothermal process was implemented to make the graphene-supported Fe 3O4 NPs. This new material was found to produce a reversible change of up to 18% in a LIB. In order to overcome some of the difficulties of testing with a LIB, a corresponding hybrid SC was designed, built and calibrated. The graphene-supported Fe3O4 NPs were found to produce a net 2% reversibility in the SC, which has not been reported before. The results from both the LIB and SC were analyzed to better understand the mechanism of switching in a spinel ferrite such as Fe3O4, which can help optimize the material for future applications.
The focus of this dissertation was on the development of a methodology for carbon-supported TM and TMO NPs for specific applications. It is envisioned that this approach and strategy will contribute towards the future optimization of similar material systems for a multitude of applications.
Wang, Fan. "Visible light photocatalysis with supported metal nanoparticles for organic synthesis." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/103567/1/Fan_Wang_Thesis.pdf.
Full textMartens, Sladana [Verfasser]. "Ultrasound supported electrodeposition of metals and preparation of metal/ceramic composites, colloidal nanoparticles and oxide materials / Sladana Martens." Clausthal-Zellerfeld : Universitätsbibliothek Clausthal, 2012. http://d-nb.info/102166779X/34.
Full textBamford, Rebecca. "Biopolymer supports for metal nanoparticles in catalytic applications." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675702.
Full textJones, Daniel R. "Using supported metal nanoparticles for the conversion of biomass derived molecules." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/99652/.
Full textMcPherson, Ian James. "An infrared spectroelectrochemical approach for understanding electrocatalysis at supported metal nanoparticles." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:eed82bd8-1863-4645-b853-7540dac6d1bc.
Full textBell, Tamsin Elizabeth. "Stabilisation of metal nanoparticles by confinement on curved supports." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/285095.
Full textMcNamara, Nicholas D. "Sonochemical Synthesis and Characterization of Metal Nanoparticle-Decorated Carbon Supports." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1311690542.
Full textAsara, Gian Giacomo. "Transition metal carbides as active phase and as support in catalysis: Insights from first principles theoretical modelling." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/454774.
Full textLos carburos de metales de transición (TMC) exhiben propiedades químicas y catalíticas similares a las de los costosos metales nobles. La conversión de alcohol, hidrogenación de olefinas y otras reacciones importantes han demostrado la aplicabilidad de estos compuestos en procesos industriales. También se sabe que nanopartículas de metales nobles (NMNPs) muestran una alta actividad catalítica a pesar de la baja o nula reactividad del metal sólido. Además, investigaciones recientes señalan que los soportes de TMC polarizan la densidad electrónica de NMNPs adsorbidos y aumentan la actividad catalítica respecto a los soportes más tradicionales de óxido metálico. Estos descubrimientos recientes han inspirado el trabajo presentado en esta tesis, realizado mediante técnicas actuales de la química cuántica. Se ha estudiado CO, CO2, H2, H2O adsorbidos sobre TiC y sobre pequeños clusters de oro adsorbidos sobre el suport. Se ha considerado la superficie (001), terrazas, escalones monoatómicos y defectos y, también, la reactividad de las moléculas adsorbidas sobre la superficie limpia de TiC (001) y en dos clusters de oro, Au4 y Au6, adsorbidos. Las barreras energéticas calculadas para la formación de metano o formaldehído a partir de gas de síntesis en la superficie limpia de TiC (001) resultan ser demasiado altas y esos procesos son inviables sobre el soporte limpio. Sobre los clusters de oro soportados sobre TiC (001) hay una mayor actividad catalítica, pero la reacción continúa siendo altamente impedida. Sin embargo la reacción de desplazamiento del gas de agua se prevé que sea rápida en el sistema Au4/TiC (001), superando los catalizadores utilizados normalmente en la industria. Experimentos recientes muestran que los clusters de Ni, Cu y Au están fuertemente deformados una vez adsorbidos sobre TMC dando lugar en catalizadores muy activos. Se ha investigado la interacción de los átomos con la fase delta del catalizador de MoC. La interacción es más fuerte para el recubrimiento más bajo considerado, la relajación de la superficie es importante y la actividad se prevé que aumente en el orden Ni> Cu> Au. Finalmente, se han considerado posibles reconstrucciones no polares para la superficie (001) de Mo2C centrándose en la energía de escisión, que es proporcional a la estabilidad de cada tipo de terminación. Las reconstrucciones no polares disminuyen la energía de escisión, confirmando la aplicabilidad de los conceptos clásicos de Tasker para óxidos a los TMC.
Carbides of the early transition metals (TMC) exhibit chemical and catalytic properties that in many aspects are very similar to those of expensive noble metals. Alcohol conversion, hydrogenation of olefins and many others important reactions demonstrated the applicability of these compounds for industrial processes. It is also known that small noble metal nanoparticles (NMNPs) show high catalytic activity despite of the poor reactivity or inertness of the bulk metal. Additionally, recent investigations pointed out that supporting TMCs polarize the electron density of adsorbed NMNPs increasing the catalytic activity respect to more traditional metal oxide supports. These recent discoveries inspired the work reported in this thesis using state-of-the-art quantum chemical techniques. We studied CO, CO2, H2, H2O molecules adsorbed on TiC and on small gold clusters adsorbed thereon. We considered the (001) extended surface, terraces, monatomic steps and kink defective sites. The reactivity of adsorbed molecules on the clean TiC (001) surface and on two gold clusters, Au4 and Au6, adsorbed thereon were also studied. Energy barriers calculated for methane or formaldehyde formation from syngas, on the clean TiC (001) surface were by far too high and those processes are unviable on the clean support. Gold clusters supported by TiC (001) show higher catalytic activity but the reaction continues to be highly hindered. However water gas shift reaction is predicted to be fast on the Au4/TiC(001) system, overtaking catalysts normally used in industry. Recent experiments show that Ni, Cu and Au clusters are strongly perturbed upon adsorption on TMC resulting in extremely active catalysts. We investigated the interaction of those atoms with the delta phase of the MoC catalyst. The interaction is stronger for the lowest coverage considered, the relaxation of the surface important and the activity is predicted to increase in the order Ni>Cu >Au. Finally, we have studied possible non-polar reconstructions of the (001) surface of Mo2C focusing on the cleavage energy, proportional to the stability of each type of termination. The non-polar reconstructions decreased the calculated cleavage energy, confirming the applicability of the classical Tasker’s concepts for oxides to TMCs.
Teng, Die. "Computational studies of transition metal nanoclusters on metal-supported graphene moiré." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51830.
Full textLiu, Zhe. "New supported metal photocatalysts for synthesis of fine organic chemicals driven by visible light." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/95889/1/Zhe%20Liu%20Thesis.pdf.
Full textPoupart, Romain. "Nanoparticules métalliques@polymères poreux : matériaux hybrides innovants pour la catalyse supportée." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1174/document.
Full textPorous materials based on polymers have been the subject of intense and various researches since their discovery until now. Their unique and remarkable properties, like their easy functionalization or their large porosity range reachable for instance, coupled with their low production cost makes them attractive for numerous applications. Among them, supported catalysis is booming, especially since the rising of nanoparticles. During this Ph.D. contribution, we have developed different polymeric materials, which could be used as support, focusing mainly onto three types: bulky materials, porous polymeric matrixes into capillaries and porous polystyrene arising from the selective degradation of diblocks copolymers.Firstly, different strategies have been employed for the immobilization and the generation of nanoparticles onto bulk materials. On the one hand, the synthesis of a monomer, bearing a disulphide bridge which can, after a reduction step, free a thiol moiety allowing us to anchor gold nanoparticles. On the other hand, a new route to reduce nanoparticle has been employed using gaseous hydrogen. In another part, the syntheses of different polymeric matrixes into capillaries have been made. First, we used an already known matrix, based on N-acryloxysuccinimide -after modification step via thiol-ene reaction and nucleophilic substitution by amines- to anchor copper or gold nanoparticles, respectively. Also, a new matrix based on cyclic carbonates has been used, after modification, to immobilized platinum nanoparticles. Finally, starting from diblocks copolymers possessing different junctions between both blocks (disulphide bridge or acetal), porous polystyrenes have been obtained. The copolymers bearing an acetal have been implemented to immobilized gold nanoparticles, catalysing several reactions like nitro reduction, boronic homocoupling as well as the cascade reaction of both
Afshani, Parichehr. "Laser Vaporization Methods for the Synthesis of Metal and Semiconductor Nanoparticles; Graphene, Doped Graphene and Nanoparticles Supported on Graphene." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/569.
Full textCarew, Alexander Jon. "Fundamental studies into the catalytic properties of metal-oxide supported gold and copper nanoparticles." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367710.
Full textXu, Chunbao. "Continuous and batch hydrothermal synthesis of metal oxide nanoparticles and metal oxide-activated carbon nanocomposites." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-07302006-231517/.
Full textTeja, Amyn, Committee Chair ; Kohl, Paul, Committee Member ; Liu, Meilin, Committee Member ; Nair,Sankar, Committee Member ; Rousseau, Ronald, Committee Member.
Neumann, Sarah [Verfasser], Sebastian [Akademischer Betreuer] Kunz, Sebastian [Gutachter] Kunz, and Marcus [Gutachter] Bäumer. "Heterogeneous Catalysis with supported Nanoparticles : Particle Size Effects and Metal-Support Interactions / Sarah Neumann ; Gutachter: Sebastian Kunz, Marcus Bäumer ; Betreuer: Sebastian Kunz." Bremen : Staats- und Universitätsbibliothek Bremen, 2019. http://d-nb.info/1203298927/34.
Full textZhu, Ju. "Synthesis of precious metal nanoparticles supported on bacterial biomass for catalytic applications in chemical transformations." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5009/.
Full textPatil, Pratap Tukaram. "Nanoscopic metal fluoride based novel solid catalysts." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2009. http://dx.doi.org/10.18452/16021.
Full textBecause of their high chemical and thermal stabilities, metal fluorides have found to be advantageous over metal oxides in such cases where reactions involving generation of corrosive acids like HCl and HF are concerned. The Sol-gel method is known for the synthesis of materials with considerably different properties to those prepared by classical routes. In this work, sol-gel route has been employed for the synthesis of binary fluorides (AlF3, MgF2, CaF2, CuF2 and FeF3), hydroxyfluorides [AlF3-x(OH)x, MgF2-x(OH)x] complex fluorides (KMgF3, K3AlF6), metal fluoride supported nanoscopic noble metals (Pd, Pt) and host-guest fluoride systems (CuF2/AlF3, FeF3/AlF3). Besides the successful synthesis of metal fluorides described above, the present thesis deals with investigation of their bulk and surface properties using various analytical and spectroscopic methods (XRD, BET, NH3-TPD FTIR-pyridine adsorption, XPS, microscopic studies) as well as with their catalytic properties for the reactions of academic and industrial interest. Metal fluorides prepared via sol-gel method have shown to possess extraordinary surface properties in terms of surface area, particle size, porosity, Lewis acidity and distortion in their structures as compared to those of classical methods like aqueous synthesis or impregnations. A homogeneous dispersion of Pd nanoparticles supported on high surface area metal fluoride prepared by this method was confirmed by XRD, XPS and TEM imaging. Catalytic properties of these materials have been investigated for dehydrofluorination of hydrofluorocarbons, isomerization of citronellal, hydrodehalogenation of chlorodifluoromethane, Suzuki cross coupling and oxidative fluorination of benzene.
Warczinski, Lisa [Verfasser], Christof [Gutachter] Hättig, Robert [Gutachter] Franke, and Reinhold [Gutachter] Fink. "Computational study of metal-support interactions for carbon-supported palladium nanoparticles / Lisa Warczinski ; Gutachter: Christof Hättig, Robert Franke, Reinhold Fink ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2021. http://d-nb.info/1233484141/34.
Full textEinakchi, Raha. "Metal Nanoparticles Over Active Ionic-Conductive Supports for the Reverse Water Gas Shift Reaction." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34462.
Full textDole, Holly. "Connecting Metal-Support Interaction and Electrochemical Promotion Phenomena for Nano-structured Catalysts." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34610.
Full textNguyen, Sorenson Anh Hoang Tu. "Immobilization of Copper Nanoparticles onto Various Supports Applications in Catalysis." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8892.
Full textDong, Hong. "Polymer fiber templates for the preparation of coaxial fibers and tubes, and as metal nanoparticle supports." Diss., Online access via UMI:, 2005.
Find full textSen, Selda. "Activity Of Carbon Supported Platinum Nanoparticles Catalysts Toward Methanol Oxidation Reaction: Role Of Metal Precursor And A New Surfactant." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609273/index.pdf.
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342 A/gPt at 0.612 V) towards methanol oxidation reaction while Catalyst IIIb (H2PtCl6 and 1-hexanethiol were used to prepare this catalyst) has the minimum activity (&
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91A/gPt at 0.580V). XRD, TEM and XPS results indicated that the optimum catalyst for methanol oxidation reaction contains about 3 nm of platinum nanoparticles, adsorbed hydroxide and water on the surface of catalyst, but sulphur. These results are in agreement with the proposed mechanism.
HONEMANN, YVONNE CARINA. "DESIGN, CHARACTERIZATION AND APPLICATION OF HETEROGENEOUS SILICA SUPPORTED CATALYSTS, BASED ON PD NANOPARTICLES AND METAL SINGLE SITES (RH, CU)." Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/214937.
Full textSen, Fatih. "The Preparation And Analysis Of New Carbon Supported Pt And Pt+second Metal Nanoparticles Catalysts For Direct Methanol Fuel Cells." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614728/index.pdf.
Full textC, 300 °
C, and 400 °
C for 4 h under argon gas. Lastly, PtRu/C catalysts, which have different atomic percent ratios of Pt and Ru (Pt/Ru: 0.8, 2.1 and 3.5), were prepared using PtCl4 and RuCl3 as starting materials and tert-octanethiol as a surfactant. Each was characterized by X-ray diffraction, transmission electron microscopy, energy dispersive analysis, X-ray photoelectron spectroscopy, cyclic voltammetry, and elemental analysis, and their activities were determined toward the methanol oxidation reaction. It has been found that all prepared catalysts are more active toward methanol oxidation reaction compared to the commercial catalysts. It was also found that increasing the temperature during the heat treatment process results in an enlargement of platinum particle size and a decrease in catalytic activity in the methanol oxidation reaction. Transmission electron microscopy shows that platinum nanoparticles are homogeneously dispersed on the carbon support and exhibited a narrow size distribution with an average particle size of about 2-3 nm in diameter. X-ray photoelectron spectra of all catalysts indicated that most of the platinum nanoparticles (>
70 %) have an oxidation state of zero and rest (<
30 %) have a +4 oxidation state with (Pt 4f7/2) binding energies of 71.2-72.2 and 74.3-75.5 eV, respectively.
Benia, Hadj Mohamed. "Spatially resolved optical measurements on supported metal particles and oxide surfaces with the STM." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15862.
Full textIn this thesis, the correlation between the optical properties and the local morphology of supported silver nanoparticle ensembles and MgO thin films deposited on Mo(001) systems is explored by means of Photon-STM. In the first section, dome and disk shaped Ag nanoparticle ensembles with increasing density on an alumina film on NiAl(110) were analyzed as well as ordered and disordered ensembles of Ag nanocolloids on HOPG. The aspect ratio of the Ag nanoparticles was found to have a significant influence not only on the Mie plasmon resonance of a single particle, but also on the electromagnetic coupling within the nanoparticle ensembles. The Mie resonance in the ensemble of dome shaped Ag nanoparticles shows a strong dependence on the interparticle distance, where it shifts to higher energies with increasing particle density, due to destructive interference effects. In the disk-like Ag ensembles, however, the plasmon energy is independent of particle-particle separation. The long-range lateral ordering of size-selected Ag nanocolloids is found to induce a high dipole-dipole coupling within the ensemble. This is mainly reflected by the enhancement of the spectral intensity of the in-plane Mie mode, due to constructive coupling. However, ensembles with either well-ordered or disordered arrangements reveal no important difference in their optical properties, reflecting the weak influence of the long-range order in the particle ensemble. Thin MgO films with different thicknesses were grown on a Mo(001) surface. The stress resulting from the 5.3% lattice mismatch between the MgO(001) and the Mo(001) lattice parameters is found to control the surface morphology of the MgO film until thicknesses of around 25ML at which flat and defect-poor films are obtained. The relaxation of the stress induces a periodic network in the first 7ML of the MgO film, consisting of alternated flat and tilted mosaics. The presence of screw dislocations, steps oriented along the MgO directions, and tilted planes is observed when the MgO films are approximately 12ML thick. In addition, an increase of the MgO work function around these new surface features is revealed from STM spectroscopy. The photon emission induced by field-emitted electron injection from the STM tip into the MgO films is dominated by two emission bands located at 3.1eV and 4.4eV. To check the origin of these bands, further experiments, namely, nucleation of Au particles and creation of F-centers on the MgO surface, have been performed. The nucleation of Au particles at the low coordinated sites is found to quench the MgO optical signal, while the creation or annihilation of F-centers does not alter the MgO emission bands. The 3.1eV and the 4.4eV bands are therefore assigned to the radiative decay of MgO excitons at corner and kink sites, and step sites, respectively. Besides, spatially resolved optical measurements in the tunneling mode of the STM revealed different light emission mechanisms. These radiative processes are mainly related to tip-induced plasmons that form between the tip and the Mo support and to electron transitions between field-emission-resonance states in the STM tip-MgO film junction. The signal from exciton decays at corners and kinks of the MgO surface is however only observed at excitation conditions where the spatial resolution is already strongly reduced.
Wyrzgol, Sonja Agnes [Verfasser], Johannes A. [Akademischer Betreuer] Lercher, and Moniek [Akademischer Betreuer] Tromp. "Controlled Catalysis by the Electronic Charge Transfer at Metal-Support Interfaces: A Study of Gallium Nitride Supported Platinum Nanoparticles / Sonja Agnes Wyrzgol. Gutachter: Johannes A. Lercher ; Moniek Tromp. Betreuer: Johannes A. Lercher." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1043802223/34.
Full textSaoud, Khaled Mohammad Eqab. "Carbon Monoxide Oxidation on Nanoparticle Catalysts and Gas Phase Reactions of Small Molecules and Volatile Organics with Metal Cations." VCU Scholars Compass, 2005. http://scholarscompass.vcu.edu/etd/1372.
Full textVijwani, Hema. "Hierarchical Porous Structures with Aligned Carbon Nanotubes as Efficient Adsorbents and Metal-Catalyst Supports." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1433350549.
Full textHong, Jingping. "Novel preparation techniques and reactivity of cobalt metal nanoparticles for synthesis of clean fuels using Fischer-Tropsch reaction." Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10018/document.
Full textFischer-Tropsch synthesis produces clean hydrocarbon fuels from natural gas, biomass or coal. These synthetic fuels are totally free of sulfur and aromatics. This thesis addresses novel approaches to the design of cobalt Fischer-Tropsch catalysts supported by mesoporous silicas. These approaches involve catalyst promotion with ruthenium and zirconium oxide, use of plasma technology for the decomposition of cobalt precursors and kinetic studies of the elementary steps of the Fischer-Tropsch by transient kinetic methods including TAP. The structure of catalysts was characterized at each stage of their synthesis and their activation by physico-chemical techniques including in-situ methods. It was shown that the promotion of catalysts with ruthenium and zirconium oxide strongly depended on the texture of the support. The promotion improved the catalytic performance more importantly for the catalysts supported by narrow pore silicas. Use of plasma technology for the decomposition of cobalt precursors allowed efficient control of the size of cobalt nanoparticles and thus resulted in the enhanced catalytic performance. Transient kinetic studies and modeling of the elementary reaction steps have provided fundamental information on the nature of active sites in the supported cobalt catalysts for Fischer-Tropsch reaction
El, Sayed Sami Verfasser], Walter [Akademischer Betreuer] [Leitner, and Andrij [Akademischer Betreuer] Pich. "Metal nanoparticles immobilized on molecularly modified supports as multifunctional catalysts for the selective hydrogenation of aromatic substrates / Sami El Sayed ; Walter Leitner, Andrij Pich." Aachen : Universitätsbibliothek der RWTH Aachen, 2021. http://d-nb.info/1233734989/34.
Full textBehafarid, Farzad. "Structure, stability, vibrational, thermodynamic, and catalytic properties of metal nanostructures: size, shape, support, and adsorbate effects." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5121.
Full textPh.D.
Doctorate
Physics
Sciences
Physics
Bernsmeier, Denis Robert [Verfasser], Ralph [Akademischer Betreuer] Krähnert, Ralph [Gutachter] Krähnert, Peter [Gutachter] Strasser, and Christina [Gutachter] Roth. "Noble metal nanoparticles supported in ordered mesoporous carbon coatings as efficient electrocatalysts for the hydrogen evolution reaction / Denis Robert Bernsmeier ; Gutachter: Ralph Krähnert, Peter Strasser, Christina Roth ; Betreuer: Ralph Krähnert." Berlin : Technische Universität Berlin, 2017. http://d-nb.info/1156014301/34.
Full textXu, Zhenxin. "Development of new macroscopic carbon materials for catalytic applications." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAF005/document.
Full textNowadays, macroscopic carbon materials are facing an increasing number of applications in catalysis, either as supports or directly as metal-free catalysts on their own. However, it is still challenging to develop hierarchical carbon-based catalyst support or catalyst using a much simple synthesis process. In the quest for novel structured carbon materials for heterogeneous catalysis we explored the potential of commercial carbon/graphite felt (CF/GF). The aim of the work described in this thesis has been the development of GF and CF monolith as metal-free catalyst for gas-phase oxidation reactions and as catalyst support, notably for palladium, for liquid-phase hydrogenation reactions, and their roles in the reaction performance of these catalysts. Due to their inert chemistry surface with inappropriate wettability, a prerequisite for such a study was to activate the origin ones. Therefore, well-rounded modified GFs and CFs were synthesized with tailored physic-chemical properties by a series of chemical treatment processes, such as oxidation, amination, thiolation, nitrogen- and sulfur-doping. The partial oxidation of hydrogen sulfide into elemental sulfur and selective hydrogenation of α, β-unsaturated cinnamaldehyde, as the sensitive test reactions to the influence of the catalyst properties on activity and selectivity, combined with characterization techniques, were chosen to investigate the effect of functionalized carbon materials on the catalytic behavior
Mazilu, Irina. "Nanoparticules métalliques déposées sur des matériaux poreux multifonctionnels pour des applications catalytiques." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2268.
Full textThe objective of the Ph.D. thesis is the development of new catalytic systems based on non-noble metal nanoparticles (Cu and/or Co MNPs) hosted in functional mesostructured hosts. To this aim, various supports are prepared by doping SBA-15 with Al, Ga and Fe heteroatoms using the two-step pH-adjustment method or by coating the SBA-15 surface with Al, Ga and Fe oxides using the melt infiltration approach. Likewise, hybrid organic-silica SBA-15 supports are obtained by partial extraction of the Pluronic P123 surfactant. The characterization and catalytic results show that the functionalization of SBA-15 supports with heteroatoms or with polyether groups originating from the native surfactant represents new strategic lines to achieve an enhanced control on the local environments of hosted MNPs and to engineer both the metal-support interaction and nanoparticle size, ultimately to fine tuning the performances of Cu and/or Co-based nanocatalysts in terms of activity and chemoselectivity for the liquid-phase hydrogenation of unsaturated aldehydes, such as cinnamaldehyde. Furthermore, SBA-15 materials containing Fe species in isolated and/or highly dispersed states are evaluated for the Fenton-type peroxidation of Reactive Red 120 azo dye, exhibiting excellent catalytic properties for the dye degradation
Wang, Changlong. "Nanomatériaux à base de métaux de transition pour la catalyse." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30106/document.
Full textTransition metal nanocatalysis is a promising area, where increased efficiency, greenness and reusability are actively sought. In this spirit, the thesis has been devoted to the synthesis, characterization and catalytic applications of new transition metal nanomaterials. Amphiphilic ligand stabilized transition metal nanoparticles catalysts have provided excellent catalytic performances in terms of activity, stability and recyclability in the 4-nitrophenol reduction, Suzuki-Miyaura coupling, transfer hydrogenation and alkyne-azide cycloaddition reactions with low amounts of metal loadings. Moreover, an efficient amphiphilic "click" CuI catalyst was also designed for part-per-million levels of alkyne-azide cycloaddition reaction in water. The design, synthesis and catalytic application of heterogeneous nanocatalysts based on graphene and metal organic framework supports have also been carried out, and their excellent catalytic properties in 4-nitrophenol reduction, Sonogashira coupling, alkyne-azide cycloaddition and hydrolysis of ammonia-borane for hydrogen generation in water under ambient conditions have been disclosed
Favaro, Marco. "A rational approach to the optimization of efficient electrocatalysts for the next generation Fuel Cells." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3424667.
Full textIl progetto di dottorato nasce all’interno del gruppo di ricerca di Superfici e Catalizzatori operante nel dipartimento di Scienze Chimiche, nell’ambito della borsa a titolo vincolato “Un approccio razionale alla ottimizzazione di elettrocatalizzatori efficienti per le celle a combustibile di nuova generazione”, finanziata da fondazione CARIPARO. Le tematica è stata focalizzata sulla preparazione e caratterizzazione di nuovi materiali a base di carbonio utilizzabili per applicazioni in celle a combustibile di tipo PEMFCs (Polymer Electrolyte Membrane Fuel Cells) ad ossigeno-idrogeno. La preparazione dei materiali è avvenuta facendo uso di differenti tecniche, in relazione al tipo di materiale oggetto di studio ed alle applicazioni che tali materiali possono offrire. Con riferimento allo studio dei sistemi modello (grafite pirolitica altamente orientata, HOPG, e carbonio vetroso, GC), il drogaggio degli stessi mediante l’introduzione di eteroatomi (in particolare azoto) è avvenuto ricorrendo alla tecnica dell’impiantazione ionica, mentre lo studio di nuove funzionalità chimiche è stato permesso dall’utilizzo di tecniche di Wet Chemistry, in particolare mutuate dalla sintesi elettrochimica. La deposizione di film sottili o di nanoparticelle (metalliche o a base di ossidi di metalli di transizione) su tali materiali modificati è stata effettuata facendo uso di tecniche avanzate come la deposizione fisica da fase vapore (PVD) in condizioni controllate di Ultra Alto Vuoto (UHV), in grado di offrire un controllo su scala atomica della deposizione di tali film. Sono state utilizzate anche tecniche di deposizione tradizionali quali la riduzione chimica o elettrochimica di opportuni precursori metallici: l‘utilizzazione di una siffatta combinazione sinergica tra tali differenti tecniche di preparazione ha permesso di ottenere materiali caratterizzati da strutture e proprietà peculiari. La caratterizzazione di tali materiali è svolta utilizzando le facilities del gruppo di Scienza delle Superfici, come la spettroscopia di fotoelettroni (XPS) o della banda di valenza (UPS), la microscopia ad effetto tunnel o a forza atomica (STM - AFM), la microscopia elettronica e la dispersione energetica dei raggi X indotta dagli elettroni (SEM-EDX), la diffrazione di elettroni lenti (LEED). Allo scopo di caratterizzare maggiormente in dettaglio la struttura e le proprietà chimiche dei materiali preparati sono state usate estensivamente le tecniche di indagine offerte dalla luce di sincrotrone (HR-XPS, NEXAFS, ARPES, ResPES, PEEM), mentre lo studio della reattività catalitica si basa su tecniche derivate dall’analisi elettrochimica, in particolare la voltammetria ciclica ed a scansione lineare del potenziale applicato, nonchè tecniche elettro-dinamiche come la voltammetria su elettrodo rotante. Infine, allo scopo di supportare i dati sperimentali o portare la comprensione delle proprietà dei materiali ad un livello più profondo, simulazioni mediante teoria del funzionale densità (DFT) sono state adottate per un approccio critico allo studio dei materiali preparati (in collaborazione con il gruppo coordinato dalla prof. Cristiana Di Valentin, Università di Milano Bicocca). Durante il corso del dottorato, diverse collaborazioni sono state perseguite con gruppi interni al Dipartimento di Scienze Chimiche o anche Esteri, come l’unità di ricerca “Interfaces and Energy Conversion E19”, dell’università tecnica di Monaco di Baviera (TUM, Technische Universität München, Germania), coordinata dai proff. O. Schneider e J. Kunze-Liebhäuser.