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Dissertations / Theses on the topic 'Bimetalic'

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Published: 18 May 2024

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1

Sengupta, Debasish. "Preparation, characterization of bimetalic nanoparticles soaked on poly -ionic resins and their ctalalytic applications." Thesis, University of North Bengal, 2014. http://ir.nbu.ac.in/handle/123456789/1827.

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2

Rowe, S. J. "Adsorption studies of simple molecules on metalic, bimetalic and semiconductor interfaces." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383911.

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3

Gallo, Irã Borges Coutinho. "Surface structure and electronic properties of carbon supported PdAu nanoparticles and their catalytic behavior toward the oxygen reduction reaction /." Araraquara, 2018. http://hdl.handle.net/11449/153370.

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Orientador: Hebe de las Mercedes Villullas
Banca: Rodrigo Fernando Costa Marques
Banca: Leandro Martins
Banca: Elisabete Inacio Santiago
Banca: Joelma Perez
Abstract: Carbon supported PdAu nanoparticles with different Au contents (20-50% in atoms) were synthesized using a procedure carried out in a liquid two-phase system. As-prepared materials presented similar average particle diameter (~3nm) with narrow distribution over the carbon support, as shown by Transmission Electronic Microscopy (TEM). The combined data from X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) suggest that nanoparticles had Pd-enriched surfaces and Au-rich interiors. Cyclic Voltammetry (CVs) studies in H2SO4 further reinforced these findings, confirming that the nanoparticle surfaces were enriched with Pd. Moreover, XPS results show that increasing the Au content of PdAu alloys leads to varying amounts of surface-like and bulk-like Pd oxide, with a significant increase of metallic Pd. This result is consistent with data of X-ray Absorption Spectroscopy (XAS) around Pd L3 edge, which revealed that Au promotes an increase in the electronic occupancy of the Pd 4d band. Therefore, this whole set of characterizations suggests that the presence of Au in PdAu nanoalloys decreases the Pd affinity for oxygen, giving Pd a more noble-like character. In addition, the influence of ligand and ensemble effects on electrochemical surface processes, such as oxide formation/reduction, CO oxidation and hydrogen adsorption were also investigated. This was also a necessary step in order to determine the best technique to measure the Electrochemical Active Area (EAA) of... (Complete abstract click electronic access below)
Resumo: Nanopartículas de PdAu suportadas em carbono com diferentes frações de Au (20-50% em átomos) foram sintetizadas em um sistema líquido de duas fases. As nanopartículas preparadas apresentaram diâmetro médio próximo a 3 nm, com uma distribuição homogênea sobre o suporte de carbono, o que foi demonstrado por microscopia eletrônica de transmissão (TEM). O conjunto dos dados coletados por difração de raios X (XRD) e por espetroscopia de fotoelétrons excitados por raios X (XPS) demonstrou que o interior das nanopartículas é enriquecido por Au, enquanto a superfície é mais rica em Pd. A análise por XPS também demonstrou que o aumento da fração de Au nas ligas de PdAu leva a uma variação na fração de diferentes espécies de óxidos de Pd e um aumento na quantidade total de Pd metálico. Este resultado é consistente com aquele obtido por espectroscopia de absorção de raios-X (XAS), realizada na borda L3 do Pd, a qual revelou que o Au promove um preenchimento eletrônico na banda 4d do Pd. Ou seja, a presença do Au parece diminuir a afinidade do Pd pelo oxigênio. Ademais, foram estudados a influência de efeitos eletrônicos e do arranjo superficial de átomos sobre os processos eletroquímicos de formação/redução de óxidos, oxidação de CO adsorvido e adsorção de hidrogênio. Estes estudos também permitiram a determinação da área eletroquímica ativa de Pd. Por meio de todas estas caracterizações foi possível traçar correlações entre a composição no cerne das nanopartículas de PdAu e suas propri... (Resumo completo, clicar acesso eletrônico abaixo)
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4

Pereira, Luis Gustavo da Silva. "Avaliação do mecanismo de oxidação de hidrogênio contaminado por monóxido de carbono em células PEMFC contendo catalisadores anódicos baseados em Pt-M/C (M=Ru, Mo, Fe e W)." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-11032010-110241/.

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A busca por fontes alternativas de energia é uma tendência mundial e, neste contexto, as células a combustível alimentadas com hidrogênio obtido pela reforma de biocombustíveis constitui uma das alternativas mais promissoras. Entretanto, o desempenho das células a combustível de membrana de troca protônica (PEMFC) com ânodos baseados em Pt é drasticamente reduzido quando se utiliza hidrogênio contaminado por CO, o qual é produzido no processo de reforma. Neste trabalho, a eletrocatálise da tolerância ao CO e a estabilidade de Pt/C, PtRu/C, PtFe/C, PtMo/C e PtW/C como eletrocatlisadores anódicos de célula a combustível PEM foram investigadas através de curvas de polarização e medidas on line de espectrometria de massas (EMS), análises de voltametria cíclica, difração de raios X (DRX) e absorção de raios X (XAS). Para todos os eletrocatalisadores bimetálicos, os quais apresentaram alta tolerância ao CO, os resultado de EMS mostraram que a produção de CO2 inicia-se a menores sobrepotenciais em relação ao eletrodo de hidrogênio quando comparado a Pt/C, confirmando a ocorrência do conhecido mecanismo bifuncional. Por outro lado, os resultados de XANES indicam um aumento de vacância da banda 5d da Pt para todos os catalisadores bimetálicos, particularmente para PtFe/C, o que leva a um enfraquecimento da ligação Pt-CO e conseqüente aumento da tolerância ao CO (efeito eletrônico). Para PtMo/C e PtRu/C alimentado com H2/CO, a formação de CO2 é observada mesmo quando a célula opera em circuito aberto, confirmando alguma eliminação de CO por um processo químico, muito provavelmente uma reação de deslocamento gás-água. Uma deterioração do desempenho de célula a combustível foi observada em uma função do tempo de operação. As causas desta degradação durante a operação a longo prazo fazem parte de um processo complexo que envolve diversos mecanismos paralelos, tais como: perda ou redistribuição do eletrocatalisador, corrosão do suporte de carbono e degradação do eletrólito (Nafion®).
The search for alternative sources of energy is a global trend, and in this context, the fuel cell supplied with hydrogen obtained by biofuels reforming is one of the most promising alternative. However, the performance of proton exchange membrane fuel cells (PEMFC) with Pt-based anode is drastically lowered when using CO-contain hydrogen, as that produced by reform. In this work, the electrocatalysis of CO tolerance and the stability of Pt/C, PtRu/C, PtFe/C, PtMo/C, and PtW/C electrocatalysts at a PEM fuel cell anode has been investigated using single cell polarization and on line electrochemical mass spectrometry (EMS) measurements, and cyclic voltammetry, X-ray diffraction (XRD), and X-ray absorption near edge structure (XANES) analyses of the electrocatalysts. For all bimetallic electrocatalysts, which presented higher CO tolerance, EMS results have shown that the production of CO2 starts at lower hydrogen electrode overpotentials as compared to Pt/C, confirming the occurrence of the so-called bifunctional mechanism. On the other hand, XANES results indicate an increase in the Pt 5d-band vacancies for the bimetallic catalysts, particularly for PtFe/C, this leading to a weakening of the Pt-CO bond, helping to increase the CO tolerance (the so-called electronic effect). For PtMo/C and PtRu/C supplied with H2/CO, the formation of CO2 is observed even when the cell is at open circuit, confirming some elimination of CO by a chemical process, most probably the water gas shift reaction. A decay of the fuel cell performance was observed as a function of the operation time. The causes of degradation during long-term operation were found to be a complex process that involves several parallel mechanisms, including: electrocatalyst loss or redistribution, carbon corrosion, and electrolyte (Nafion®) degradation.

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5

Galhardo, Thalita Soares. "Oxidação de glicerol utilizando catalisadores mono e bimetálicos à base de nanopartículas de Pt, Cu ou Ni suportadas em carvão ativado." reponame:Repositório Institucional da UFABC, 2017.

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6

Atmatzakis, Evangelos. "Bimetallic photonic metamaterials." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/399982/.

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In this thesis, I introduce bimetallic ring resonator arrays as a platform for enhancing and controlling magneto-optical and thermoelectric effects. By taking advantage of differences in the physical (optical, electronic, thermal, magnetic) properties of the two elements comprising the resonators, I have demonstrated tailoring of the optical absorption and the Faraday effect, and generation of THz magnetic pulses. In particular: I have theoretically predicted for the first time the light-driven generation of intense, highly-localised, THz magnetic pulses in thermoelectric metamaterials. Excitation of bimetallic plasmonic resonators by ultrafast electromagnetic pulses, raises the electron energy and causes them to diffuse towards colder regions due to the thermoelectric effect. In addition, the resonator design and the excitation polarization create a situation in which electrons are forced to migrate in the azimuthal direction along the circumference of the ring, giving rise to a quasistatic magnetic field of up to 0:35 T, localized in an area with diameter of 70 nm. The time dynamics of the pulse generation process are controlled by electron energy relaxation to lattice through electron-phonon collisions, which lead to pulse duration of ~ 1:8 ps. I have demonstrated experimentally for the first time enhanced Faraday rotation in bimetallic single-layer metamaterials. The design of the unit cell resonator allows light confinement in the vicinity of the magneto optically active ferromagnetic metal which results in enhancement of the Faraday effect. Tailoring the size of the ferromagnetic component, which simultaneously controls the magneto-optical response and the dissipation losses in the system, results in a design which rotates the polarization azimuth of an incident electromagnetic wave by up to 1 mrad. I have demonstrated for the first time resonant absorption in single-layer Au/Ni photonic metamaterials and investigated its dependence on wavelength and polarization. A hybrid system consisting of materials that exhibit different levels of dissipation losses can be excited in ways which enable control over the spectral position, bandwidth and level of the optical absorption. The plasmonic modes mediating the metamaterial absorption are identified by a detailed computational analysis, which is in good agreement with the far-field experimental observations. I have fabricated for the first time single-layer, bimetallic ring resonator arrays consisting of noble and ferromagnetic metals. An optimized, multi-step electron beam lithography process has been developed in order to bring together, with sub-10 nm accuracy, the two metallic sectors and form 100 x 100 µm2 ring resonator arrays. I have developed a sensitive polarimeter apparatus to probe polarization rotation in metamaterial arrays. Following the principles of polarization modulation polarimetry, I have built a state of the art experimental setup that resolves angles as low as 10-5 radians in finite size, strongly scattering samples which have dimensions down to 50 x 50 µm2.

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7

Morris, James Alan. "Palladium-ruthenium bimetallic cascades." Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405707.

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8

Migliaccio, Luca. "Bimetallic catalysts for CO2 electroreduction." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14470/.

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Over the last decades, many steps have been taken in the search for an effective method to reduce carbon dioxide to small organic molecules that can be used as fuel or building blocks for the chemical industry. The object of this work is to prepare two bimetallic electrocatalysts utilizing Cu combined with Au or In for the efficient and selective reduction of CO2 to CO, HCOOH and small fuels molecules. The copper-gold electrode is prepared through the electrodeposition of Cu on the surface of Au, using the underpotential deposition (UPD) technique to obtain a copper monolayer. The prepared electrode shows a high current density compared to Au electrode. Bimetallic metal oxides of CuInO2 is used as the precursor to prepare Cu-In alloys electrodes for electrochemical reduction of CO2. The electrocatalyst preparation is carried out using a thermal reducing treatment able to form different catalytic surfaces with different Cu-In alloys or single-phase metals. The best sample shows a high faradaic efficiency toward CO (71%) at the low overpotential of −0.8 V vs RHE. This study shows two examples of scalable and inexpensive preparation methods of bimetallic surfaces, which may use as selective electrocatalysts for the aqueous reduction of CO2.

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9

Merrifeild, Ruth Corrin. "Bimetallic Nanoclusters and Protein Interactions." Thesis, University of Birmingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522011.

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10

Cooper, Ian Ronald. "Palladium-indium bimetallic cascade processes." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401087.

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11

Davies, S. J. R. "The structure of bimetallic catalysts." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373245.

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12

Ence, Chloe Christine. "Organic Synthesis using Bimetallic Catalysis." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8397.

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Bimetallic Catalysis is an emerging field of study that uses two metals to cooperatively perform organic transformations. These metals can serve to activate or bind substrates in order to increase the rate and selectivity of reactions. This work first describes the synthesis and utilization of six new chiral, titanium-containing phosphinoamide ligands. These Lewis acidic ligands withdraw electron density from an active palladium center to induce chirality and increase the rate of allylic amination of hindered, secondary N-alkyl amines. X-ray quality crystals were grown for each ligand and completed the allylic amination of hindered secondary amines in minutes whereas other non-titanium-containing ligands produced trace product. Although enantioselectivity was low initially, through a dynamic kinetic resolution enantioselectivity was increased over time, reaching 53% enantioselectivity. The second type of bimetallic catalysis discussed is dinuclear Pd(II) and Pd(I) catalysis. These dimers were built on a 2-phosphinoamide ligand scaffold and present interesting molecular structure and unique reactivity. These dimers were found to perform tandem arylketone coupling to produce disubstituted naphthalene products under oxidative conditions. It is proposed that the Pd(II) dimer undergoes oxidative addition to produce a Pd(III) dimer which subsequently produces an aryl-ketone intermediate. This process is made possible by the cooperativity of the two palladium centers which enable the formation of a Pd(III) dimer, circumventing the need for the high energy Pd(IV) oxidation state. Oxidative conditions then allows coupling and cyclization of a second ketone to form the naphthalene product.

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13

Kühn, Laura. "Bimetallic aerogels for electrocatalytic applications." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-226469.

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Polymer electrolyte fuel cells (PEFCs) have emerged as a promising renewable emission-free technology to solve the worldwide increasing demand for clean and efficient energy conversion. Despite large efforts in academia and automotive industry, the commercialization of PEFC vehicles still remains a great challenge. Critical issues are high material costs, insufficient catalytic activity as well as longterm durability. Especially due to the sluggish kinetics of the oxygen reduction reaction (ORR), high Pt loadings on the cathode are still necessary which leads to elevated costs. Alloys of Pt with other less precious metals (Co, Ni, Fe, Cu, etc.) show improved ORR activities compared to pure Pt catalysts. However, state-of-the-art carbon-supported catalysts suffer from severe Pt and carbon corrosion during the standard operation of PEFCs, affecting their reliability and long-term efficiency. Multimetallic aerogels constitute excellent candidates to overcome these issues. Due to their large open pores and high inner surface areas combined with electrical conductivity, they are ideal for applications in electrocatalysis. In addition, they can be employed without any catalyst support. Therefore, the fabrication of bimetallic Pt-M (M=Ni, Cu, Co, Fe) aerogels for applications in fuel cell catalysis was the focus of this thesis. Based on a previously published synthesis for Pt–Pd aerogels, a facile one-step procedure at ambient conditions in aqueous solution was developed. Bimetallic aerogels with nanochain diameters of as small as 4 nm and Brunauer-Emmett-Teller (BET) surface areas of up to 60 m2/g could be obtained. Extensive structure analysis of Pt–Ni and Pt–Cu aerogels by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (STEM-EDX) and electrochemical techniques showed that both metals were predominantly present in their metallic state and formed homogeneous alloys. However, metal (hydr)oxide byproducts were observed in aerogels with higher contents of non-precious metal (>25 %). Moreover, electronic and geometric structures were similar to those of carbon-supported Pt alloy catalysts. As a result, ORR activites were comparable, too. A threefold improvement in surface-specific activity over Pt/C catalysts was achieved. The mass-specific activites met or exceeded the U.S. Department of Energy (DOE) target for automotive PEFC applications. Furthermore, a direct correlation between non-precious metal content in the alloy and ORR activity was discovered. Aerogels with nonprecious metal contents >25% turned out to be susceptible to dealloying in acid leaching experiments, but there was no indication for the formation of extended surface structures like Pt-skeletons. A Pt3Ni aerogel was successfully employed as the cathode catalyst layer in a differential fuel cell (1 cm2), which is a crucial step towards technical application. This was the first time an unsupported metallic aerogel was implemented in a PEFC. Accelerated stress tests that are usually applied to investigate the support stability of fuel cell catalysts revealed the excellent stability of Pt3Ni alloyed aerogels. In summary, the Pt alloy aerogels prepared in the context of this work have proven to be highly active oxygen reduction catalysts with remarkable stability.

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Zhu, Chengzhou, Dan Wen, Martin Oschatz, Matthias Holzschuh, Wei Liu, Anne-Kristin Herrmann, Frank Simon, Stefan Kaskel, and Alexander Eychmüller. "Kinetically controlled synthesis of PdNi bimetallic porous nanostructures with enhanced electrocatalytic activity." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-208520.

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15

Berg, Katja E. "Bimetallic model compounds for artificial photosynthesis /." Stockholm, 1997. http://www.lib.kth.se/abs98/berg0109.pdf.

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16

Simpkins, Simon M. E. "Bimetallic organoiron dipoles as NLO materials." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365015.

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17

MacLeod, Norman. "Alloy formation in bimetallic reforming catalysts." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388553.

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18

McCaffrey, Shaun. "Enantioselective Pd/In bimetallic cascade processes." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432336.

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19

Campbell, Steven Bruce. "Characterisation of bimetallic diesel oxidation catalysts." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=211242.

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With mobile emission limits worldwide becoming more stringent, catalysts have increased in complexity to achieve improved activities and selectivities. This has required catalysts to be characterised under more severe conditions e.g. after extended thermal treatments to simulate catalyst lifetime. Detailed characterisation may allow a deeper understanding of the interactions within these catalysts and lead to improvements in catalyst design. The characterisation of these and other sophisticated catalysts may be improved by the development of an advanced characterisation technique using quantitative infrared spectroscopy. Bimetallic PtPd diesel oxidation catalysts which had been subjected to contrasting ageing processes were characterised using a variety of methods to study the surface composition and structure. Through FTIR studies, differences have been shown in the surface structure between the catalysts and using a semi-quantitative methodology, surface compositions have been determined. In addition to FTIR studies, characterisation has been performed using temperature programmed methods and simple oxidation reactions with in-situ diffuse reflectance spectroscopy. The results show clear evidence for the interaction of the two metals and also improved activity compared with the monometallic analogues. Simple oxidation reactions showed no significant structure sensitivity in either the CO or C3H6 oxidation reactions, however the NO oxidation reaction was shown to be sensitive to the catalyst structure following reduction. While FTIR was used to characterise the catalysts, experiments were performed with the aim to develop a quantitative methodology for FTIR applied to supported Pd catalysts. Investigations have shown the key considerations and factors required to develop an accurate quantitative method for CO adsorption on supported metal catalysts. The results of the investigations show a new method that can be applied for quantitative IR spectroscopy and the degree of complexity of the system when determining the molar absorption coefficients from complex spectra.

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Schütze, Mike. "Bimetallic Complexes for Cooperative Polymerization Catalysis." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E4A0-A.

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21

Judd, Lawrence. "Bimetallic complexes of meta-substituted phosphinobenzenes." Thesis, University of Warwick, 1988. http://wrap.warwick.ac.uk/110018/.

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The ligand m-bis(diphenylphosphino)benzene (m-BDPPB) has been prepared and has been found to form bimetallic complexes of various structural types. The most common of these is the trans.trans face-to-face structure as demonstrated by the complex [CI2Pt(u-m-BDPPB)2PtCL2. Other bimetallic complexes such as [X(Me)Pt(u-m-BDPPB)2Pt(Me)X] (X = Cl or I) and [Me(sol)Pt(u-m-BDPPB)2Pt(sol)Me]2+ (sol = acetone or acetonitrile) have been prepared and have been shown by 31P-{1H) and 1H n.m.r. spectroscopy to be fluxional at room temperature. The probable processes giving rise to this fluxionality are discussed in detail. Bimetallic complexes containing three bridging diphosphines such as [M2(u-m-BDPPB)3] (M = Pt or Pd) and [ClRh(u-m-BDPPB)3RhCl] have also been prepared and some of their chemistry investigated. The ability of the bimetallic complexes [CL2Pt(u-m-BDPPB)2PtCL2], [ClRh(u-m-BDPPB)3RhCl], [(OC)(H)Rh(u-m-BDPPB)3Rh(H)(CO)] and [(l,5-cod)M(u-m-BDPPB)2M(l,5-cod)]2+ (M = Rh or Ir) to act as a catalyst for the activation of substrates such as hex-l-ene, buta- 1,3-diene and o-, m- and p- diiodobenzene has been investigated. The new phosphine m-hydroxy(diphenylphosphino)benzene has been prepared and some of its complexes with platinum(II) and palladium(II) are described.

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Eliáš, Lumír. "Zavedení a optimalizace linky pro výrobu bimetalických komor do vstřikovacích lisů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-227962.

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The Diploma Thesis deals with the explanation and the effective solution of the initial problems during a production line implementation of different type in the existing process. In order to make the production economical effective and correspondent with decided standards and customer requirements, the thesis is based on the identification and elimination of abnormal phenomenon by new production line implementation for bimetallic barrels.

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Huang, Wei. "Selective hydrogenation on zeolite-supported bimetallic catalysts." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 0.90 Mb., p. 76, 2005. http://proquest.umi.com/pqdlink?did=1037889271&Fmt=7&clientId=8331&RQT=309&VName=PQD.

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Zhou, Shenghu. "Architecturally controlled bimetallic nanoparticles for heterogeneous catalysis." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/6722.

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Thesis (Ph. D.)--University of Maryland, College Park, 2007.
Thesis research directed by: Chemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Beck, Victoria Holly. "Synthesis and characterisation of bimetallic organometallic complexes." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403935.

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Maggini, Simona. "Novel phosphinooxazolines as precursor of bimetallic systems." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433366.

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27

Nanada, Swagata. "Bimetallic alkoxides as potential lewis acid catalysts." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533694.

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Chiffey, Andrew Francis. "Bimetallic compounds of palladium, platinum and gold." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294602.

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Cambanis, George. "Platinum bimetallic catalysts for fuel cell applications." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/37958.

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Hardeman, David. "Growth of carbon nanotubes using bimetallic catalysts." Thesis, University of Cambridge, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709528.

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Wells, Jordann Ashley Logan Slovenne Denis. "Bimetallic actinide complexes for small molecule activation." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31167.

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The work described in this thesis concerns the synthesis of actinide complexes and their reactivity towards small unsaturated molecules. Complexes bearing tetraphenoxide, borohydride and boroxide ligands have been evaluated. Additionally, work towards the synthesis of heterobimetallic uranium transition metal complexes and their applications in catalysis is discussed. Chapter one reviews important organoactinide complexes reported in the literature which effect chemical transformations on small unsaturated substrates. Actinide complexes supported by aryloxide or borohydride ligands are reviewed, along with actinide complexes in which metal p-arene interactions are present. Chapter two reports the synthesis and characterisation of a set of tetraphenol ligands, in addition to a number of attempted synthetic routes to tetraphenol ligands with alternate substitution. The chemistry of those tetradentate aryloxide ligands is introduced with bimetallic uranium(IV) and thorium(IV) complexes using different An(IV) and U(III) precursors. Chapter three reports the synthesis and characterisation of monometallic uranium and thorium complexes using a tetraphenol ligand. The varying chemistry between the two similar An(IV) ions, where the uranium complexes exist as a mixture of oligomers and the thorium complexes remain as well defined mononuclear complexes, is discussed within. A range of base adducts of mononuclear actinide complexes are reported, including a thorium trimethylsilylazide complex, a rare example of a metal organoazide. Chapter four describes the synthesis of homoleptic boroxide and heteroleptic borohydride complexes of uranium(III). The reactivities of these complexes with small unsaturated molecules are assessed, including the reaction of a low coordinate uranium(III) boroxide complex towards CO2 to provide a dinuclear uranium carbonate bridged complex. Chapter five introduces work towards heterobimetallic uranium transition metal complexes carried out in the Arnold group. The application of these complexes towards ring opening polymerisation chemistry is discussed in addition to investigations into the incorporation of transition metals into uranium(IV) complexes. Chapter Six presents the detailed experimental methods used to carry out this research.

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Luo, Kai. "Spectroscopic characterization of monometallic and bimetallic model catalysts." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1709.

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33

Roudgar, Ataollah. "Local reactivity of bimetallic overlayer and cluster systems." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971640084.

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34

Scherlin, Freddy. "Synthesis and characterization of bimetallic platinum-thallium compounds." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15403.

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The solid bimetallic compounds TtPt(CN)₄(ClO₄) and TtPt(CN)₄(NO₃) have been prepared by reactions between tetracyanoplatinate complex [Pt(CN)4]2- and aqueous solutions of Tl(ClO₄)₃ and Tl(NO₃)₃, respectively. The elemental analysis (N, C, H, Tl) of the compound has been carried out. The results of the analysis are reasonably consistent with the above compositions of the compounds. The bimetallic compounds have been characterized by IR and Raman spectroscopy as well as X-ray diffraction. IR and Raman spectra of the Tl-Pt compounds confirm presence of the perchlorate and nitrate counter ions in the solid. The presence of a direct Tl-Pt metal-metal bond in the compounds is confirmed by appearance of a strong vibrational band the low frequency region of the vibrational spectra.

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35

Gjervan, Torbjørn. "Studies of bimetallic particle formation in reforming catalysts." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2000. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1482.

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36

Rademacher, Carolin [Verfasser]. "Synthesis and analysis of bimetallic nanoparticles / Carolin Rademacher." Bielefeld : Universitätsbibliothek Bielefeld, 2014. http://d-nb.info/1052627609/34.

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37

Collins, Richard. "Bimetallic group 4 complexes as olefin polymerisation catalysts." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:f6cad6bf-c925-4cda-9797-7b1916f98a0f.

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This Thesis describes the synthesis and characterisation of half-sandwich bimetallic complexes supported by κ¹-amidinate ligands with different bridging moieties. Chapter 1 introduces homogeneous polyolefin catalysis with a focus on Group 4 metals. The mechanism, catalyst development and the activation chemistry of metallocene and post-metallocene catalysts are discussed. The beneficial properties generated by bimetallic catalysts through cooperative interactions are introduced. Chapter 2 describes the synthesis, structures and copolymerisation capabilities of cyclopentadienyl-amidinate phenylene bridged bimetallic titanium complexes. A series of monometallic cyclopentadienyl-amidinate dimethyl and dichloride titanium complexes are presented for comparison. A detailed description of their activation to form well-defined cationic species is presented. Chapter 3 describes the synthesis, structures and copolymerisation capabilities of cyclopentadienyl-amidinate titanium bimetallic complexes with conformationally constrained and ferrocenyl covalent tethers. Alongside the ferrocenyl complexes introduced in Chapter one, an electrochemical analysis of all ferrocene based complexes will be discussed. Chapter 4 details two different binuclear cocatalysts and their performances in a high temperature EPDM copolymerisation study. The form of the catalytic species is investigated through abstraction reactions with monometallic and bimetallic complexes previously introduced. Chapter 5 describes the synthesis of a bimetallic zirconium complex and attempted synthesis of a Group 4 heterobimetallic complex. A parallel polymerisation reactor (PPR) experiment on in situ generated precatalysts is discussed, which is supported by synthetic and polymerisation experiments. Chapter 6 presents full experimental procedures and characterising data for the new complexes reported in this Thesis.

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Persson, Katarina. "Bimetallic palladium catalysts for catalytic combustion of methane." Licentiate thesis, Stockholm, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-332.

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39

Snyder, Brian. "An investigation into bimetallic hollow nanoparticles in catalysis." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47614.

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Nanocatalysis, catalysis using particles on the nanoscale, is an emerging field that has tremendous potential. Nanoparticles have different properties than bulk material and can be used in different roles. Macro sized precious metals, for example, are inert, but nanoparticles of them are becoming more widely used as catalysts. Understanding the manner in which these particles work is vital to improving their efficacy. This thesis focuses on two aspects of nanocatalysis. Chapter 1 begins with a brief introduction into nanotechnology and some of the areas in which nanoparticles are different than bulk particles. It then proceeds into an overview of catalysis and nanocatalysis more specifically. Focus is brought to the definitions of the different types of catalysis and how those definitions differ when applied to nanoparticles. Chapter 2 is in finding an inert support structure to more easily assist in recycling the nanoparticles. Polystyrene microspheres were studied and found to prevent platinum nanoparticles from aggregating in solution and possibly aid in recycling of the nanoparticles. These nanoparticles were used in catalysis, aiding in the reduction of 4-nitrophenol in the presence of sodium borohydride. While the rate decreased by a factor of ~ 7 when using the polystyrene, the activation energy of the reaction was unaltered, thus confirming the inactivity of the polystyrene in the reaction. In Chapter 3, nanocatalysis was studied by examining bimetallic hollow nanoparticles with specific attention to the effect of altering the ratios of the two metals. Ten different bimetallic nanocages were tested in an electron transfer reaction between hexacyanoferrate and thiosulfate. Five PtAg nanocages and five PdAg with varying metal ratios were prepared and studied. It was found that while silver cubes immediately precipitate out of solution when combined with thiosulfate, a small amount of either platinum or palladium allows the particles to remain in solution and function as a substantially more effective catalyst. However, as additional Pt was added the activation energy increased. To obtain a better understanding of the catalysis using bimetallic cages, the evolution of these cages was studied as the 2nd metal was added. Initially the particle edge length increased and then slowly decreased back to the size of the template cubes. The increase in edge length suggests of addition of material to the nanoparticles. This indicated the 2nd metal is on the outside of the cage, which was confirmed using UV-Vis spectroscopy and EDS mapping. By understanding how these bimetallic particles evolve, we may be able to manipulate these synthetic methods to more precisely design nanoparticles for catalysis.

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O'Brien, S. D. "The preparation and properties of bimetallic hydrogenation catalysts." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421011.

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Nuttall, Christopher John. "Bimetallic tris-oxalate magnets : synthesis structure and properties." Thesis, University College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299144.

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Marshall, Robert. "Preparation of bimetallic catalysts by surface organometallic chemistry." Thesis, Open University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265345.

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43

Chantry, Ruth L. "Characterising the structure and properties of bimetallic nanoparticles." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4500/.

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The work presented in this thesis explores the use of aberration corrected scanning transmission electron microscopy (ac-STEM) in characterising the structure and properties of bimetallic nanoparticles. STEM imaging and energy dispersive X-ray spectroscopy (EDX) are used to show the influence that reaction kinetics have over the formation of structure in AuRh and AuPd nanorods. Correlated imaging and electron energy loss spectroscopy (EELS) are used to characterise the localised surface plasmon resonance (LSPR) response of single AuPd and AuRh nanorods, showing how ac-STEM can be used to identify the origins of this response. Finally the full range of ac-STEM techniques (imaging, EDX and EELS) are applied to identify the formation of ordered AuAg oxide structures in AuAg nanoparticles that have been aged in air and to show the impact their structural evolution has on LSPR properties. Through this work we show that the unrivalled spatial resolution and range of elementally sensitive techniques available in ac- STEM is essential to the characterisation of bimetallic nanoparticles. The capabilities of these instruments give the possibility to gain a fundamental understanding of the metalmetal interactions taking place in these systems, and thus form connections to the properties that result from them, which is necessary to their effective use in both catalytic and plasmonic applications.

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Khimyak, Tetyana. "New bimetallic clusters - precursors for heterogeneous nano-catalysts." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620698.

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45

Wise, Anna MacDonald. "Characterisation of bimetallic alloy and core-shell electrocatalysts." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/341819/.

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Core-shell electrocatalysts are of interest for the oxygen reduction reaction in proton exchange membrane fuel cells as enhancements in activity have been reported compared to the traditionally-used Pt/C electrocatalysts. To fully understand the origin of the activity of these samples, and how the structure changes in the electrochemical environment, full in situ structural characterisation is required. The aim of this work was to develop and apply in situ synchrotron based X-ray characterisation techniques (EXAFS, WAXS, SAXS and ASAXS) to study a set of well-defined Pd-core, Pt-shell electrocatalysts with 0.5, 1, 2 and 4 monolayers (ML) of Pt, with the primary motivation of determining the advantages and limitations of each technique when applied to materials of this nature. Measurements were conducted in and ex situ to study the effect of Pt-shell thickness on the structure of the nanoparticles and the response to applied electrode potential. Catalyst electrodes subjected to accelerated ageing tests were also characterised to investigate the mechanisms of degradation responsible for an observed loss in electrochemical surface area, with the dominant mechanism found being dissolution for the core-shell catalysts with ≤ 2 ML shell and coalescence (Ostwald ripening) for the 4 ML. EXAFS was found to be the most useful of the four techniques owing to the detailed structural information obtainable and the relative ease of data collection. The SAXS data provided information not obtained from the EXAFS, and combined with electrochemical measurements, enabled determination of the mechanisms of degradation. WAXS provided complementary information to the EXAFS. Attempts to fit the ASAXS data with a simplistic model were unsuccessful, thus, without the application of more complex theoretical models, little additional information could be obtained from this technique.

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Van, Aswegen Sivan. "Exploring heterogeneous bimetallic nanoparticle catalysts for sustainable oxidations." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/415218/.

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Prior work in the group has focused on developing the synthesis and activation of supported monometallic noble metal nanoparticle (Au, Pt and Pd) copper chlorophosphate frameworks (CuClPs), and exploring their potential as oxidation catalysts. Herein, bimetallic variants (AuPt/CuClP, PtPd/CuClP and AuPd/CuClP) have been synthesised, characterised and employed in catalytic reactions. Characterisation by TEM and XPS revealed the presence of small, metallic nanoparticles in the bimetallic CuClP materials, with the AuPt/CuClP sample containing the smallest and most uniform particles. The bimetallic AuPt/CuClP material was found to be highly active in the aerobic oxidation of KA-oil, with the catalyst reduced at 300 °C giving the most promising result (89 mol % conversion, > 99 % selectivity to cyclohexanone). The AuPt/CuClP catalyst reduced at 300 °C showed the most promise, achieving the highest conversion of the monometallic and bimetallic CuClP catalysts, while also showing an increased stability over a range of temperatures compared to the monometallic analogues. Through physical mixture tests, the nature of the bimetallic nanoparticles in the AuPt/CuClP catalyst reduced at 250 °C was probed and predicted to contain discrete sites, however the increased thermal stability of the AuPt/CuClP reduced at 300 °C alluded to a synergistic interaction between the Au and Pt species, suggesting the possibility of alloyed nanoparticle sites. The catalytic potential of the CuClP materials was further explored in the oxidation of valerolactam, the hydrogenation of furfural, the Beckmann rearrangement of cyclohexanone oxime, and the Baeyer-Villiger oxidation of cyclohexanone. However, the presence of unexpected acid-catalysed products gave rise to the consideration of the inclusion of weak Lewis acid sites in the CuClP framework, although acid characterisation is required in order to confirm this.

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47

Sundavadra, Bharat Viram. "The organometallic chemistry of alkyne-bridged bimetallic complexes." Thesis, University of Cambridge, 1993. https://www.repository.cam.ac.uk/handle/1810/272569.

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48

Lee, Adam Fraser. "Structural and catalytic properties of bimetallic Pd systems." Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/273061.

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49

Dylla, Anthony Greg. "Synthesis, characterization and catalytic properties of bimetallic nanoparticles." College Park, Md.: University of Maryland, 2009. http://hdl.handle.net/1903/9609.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2009.
Thesis 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.

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50

Moon, Il Kweon. "Optical performance of bimetallic mirrors in thermal environments." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279805.

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Evaluation of the optical performances of bimetallic mirrors with various substrate shapes was conducted using the finite element analysis program, SDRC-IDEAS. In these analyses, two different plating materials, nickel and aluminum were considered for an aluminum and a beryllium mirror substrate. Thermal environments used in this study are: a unit thermal soak (temperature difference), an axial temperature distribution, and radial temperature distributions on the mirror substrate. The goal of this study is to optimize the optical surface quality for various plating thicknessess. Surface errors, individual aberration terms, such as piston, tilts, focus and other aberrations were obtained by the program PCFRINGE. It was found that the optical performances of bimetallic mirrors depend on the plating material, plating thickness, and the mirror substrate materials. The optimum plating thickness combinations were determined based on plating material and mirror substrate with variation of temperature distributions. The results were compared with the optical surface errors and the corrected surface errors. The results indicate that there does not exist a definite common rule for the optimum, but a detailed analysis such as presented herein is generally needed to design bimetallic mirrors in a thermal environment.

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