Nuevas nanoestructuras plasmónicas de oro y oro-plataEstudio de sus propiedades catalíticas, fotocatalíticas y fototérmicas

Abstract

The present work is devoted to the synthesis, characterization, study of properties and possible applications of different plasmonic monometallic gold and bimetallic gold and silver nanostructures, formed from the decomposition of organometallic compounds. Control over this synthesis is essential to modulate their shape, size and composition, characteristics closely related to their properties, which will allow us to modify them as required. On the other hand, the use of a shape-directing agent, which allows us to modify the environment of the precursor, will be decisive in the formation of nanostructures, limiting their growth or favoring their organization. Thus, this work is structured in three chapters: The first one focuses on the self-assembly of small-sized spherical gold nanoparticles to form new, more complex nanostructures called colloidosomes. Due to their interesting morphology, these species show an intense and broad absorption in the visible region, which will allow them to take advantage of a large part of this radiation to generate heat, considerably increasing their temperature. In addition, the medium in which they are found will be critical to favoring aggregation/disaggregation processes of the smaller nanoparticles, which will drastically modify their plasmonic properties. The second chapter details the controlled formation of bimetallic gold and silver nanorods whose dimensions are controlled through the stoichiometry between the organometallic precursor and a shape directing agent (oleic acid). These materials present an intense radiation absorption in the near infrared region due to their surface plasmon resonance, which will allow them to present a high conversion of light into thermal energy both in the solid state and in solution. In addition, they show a great potential in reduction reactions, which makes them suitable materials for photothermal therapy or photocatalytic applications. Finally, the third chapter is dedicated to the synthesis of new hybrid materials through the deposition of the nanostructures described in the first two chapters on different substrates such as graphitic carbon nitride, silica nanoparticles or Prussian blue nanocubes. The combination with these different materials will allow extending and enhancing the properties of the nanostructures used, and may, even, generate a synergistic effect between both. Like the isolated nanostructures, the new hybrid nanomaterials display a strong photothermal effect and the ability to catalyze different reduction reactions. In addition, the combination with a semiconductor, such as graphitic carbon nitride, will make it possible to carry out and improve different degradation reactions of persistent pollutants in water.