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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Nanomateriais de PdAu e PdPt com forma composição e estrutura controlada para aplicações em catálise / PdAu and PdPt nanomaterials with shape, composition and structure controled for catalysis applications

Yamada, Liliam Kaori 29 November 2018 (has links)
Nanomateriais baseados em paládio (Pd) desempenham um papel central em catálise. Como suas prorpiedades catalíticas dependem de seus diversos parâmetros físico e químicos, a sua síntese controlada tem grande apelo com contexto do controle e otimização de performances. Nesse trabalho desenvolvemos metodologias simples, versáteis e ambientalmente amigáveis para a preparação de nanoestruturas de Pd com tamanho e forma controlada, seguida pelo seu uso como materiais de partida para a preparação de estruturas bimetálicas contendo ouro (Au) e platina (Pt). Espeficificamente, focamos em nanopartícuals (NPs) de Pd na forma de moitas, prisma e cubo côncavos. Com respeito aos materiais bimetálicos, desenvolvemos estruturas do tipo core-shell, tadpoles, e partículas de Au e Pt decoradas sobre as NPs de Pd. Seguda da síntese, estudamos a performance catalítica dos materiais obtidos frente a hidrogenação do p-nitrofenol (p-NPh) e a oxidação do p-aminotiofenol (PATP) mediada pela ressonância plasmônica de superfície (SPR). Nossos resultados mostraram que as atividades foram dependentes dos parâmetros físicos e químicos que definem as nanoestruturas e que materiais controlados tem desempenho superior ao material comercial. Acreditamos que os resultados desenvolvidos nessa tese contribuem para os mecanismos que governam a síntese controlada de NPs baseadas em Pd, Au e Pt, que pode servir como base para a descoberta de nanomateriais com maior complexidade estrutural e composicional visando aplicações em catálise e plasmônica. / Palladium-based (Pd) nanomaterials play a central role in catalysis. As the catalytic properties of thse materials depend on its various physical and chemical parameters, its controlled synthesis has great appeal in order to control and optimize performances. In this work, we developed facile, versatile and environmentally friendly methodologies for the preparation of Pd nanostructures of controlled sizes and shapes, followed by their use as starting materials for the preparation of bimetallic structures containing gold (Au) and platinum (Pt). Specifically, we focused on Pd nanoparticles (NPs) in the form of bushes, prisms and concave cubes. With respect to bimetallic materials, we have developed core-shell structures, tadpoles, and Au and Pt particles decorated on the Pd NPs. Following their synthestic development, we studied the catalytic performance of the obtained materials towards the hydrogenation of p-nitrophenol (p-NP) and the oxidation of p-aminothiophenol (PATP) mediated by surface plasmon resonance (SPR) excitation. Our results showed that the activities were dependent on the physical and chemical parameters that define the nanostructures and that controlled materials performed better than the commercial conterpart. Overall, we believe that the results developed in this thesis contribute to the mechanisms governing the controlled synthesis of NPs based on Pd, Au and Pt, which can serve as a basis for the discovery of nanomaterials with greater structural and compositional complexity for catalytic and plasmonic applications.

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