Síntesis fotoasistida de materiales de carbono nanoporosos

Resumen

The main objective of this thesis was to explore the possibility of using photo-assisted reactions to prepare porous carbons and metal/carbon nanohybrids. Thus, UV photoinduced polycondensation was implemented to freeze the auto-organized structures formed by different phenolic resins in the presence of a surfactant (as mesostructure director agent). The pyrolysis of these organic precursors opens the way to nanoporous carbon materials with controlled textural and physicochemical properties. By appropriate choice of the organic precursor and synthesis parameters, it was possible to control the morphology, structural order, and pore size distribution of the final carbon materials throughout the micro/mesoporous range. The degree of crosslinking of the photopolymerized resin was determined by the structure, as well as the number of reactive positions in the organic precursors (i.e., the ortho- or para-substituted positions of the hydroxyl group moieties). Thus, for example bisphenol A (di-phenolic type), resulted in highly branched clusters that presented low interaction with the template, giving rise to a structure with dense porosity mainly composed of narrow micropores. On the other hand, the poly hydroxy-benzene type precursors can be assembled into large crosslinked clusters, which interact with the surfactant (template), promoting a more open structure. The incorporation of metal ions (Au3+, Ag+) during the one-pot process, allowed the simultaneous photoassisted polycondensation of the phenolic resin and the photoreduction of metal ions, yielding metal nanoparticles (NPs). The resulting materials contain highly dispersed metal NPs in the carbon matrix, which induces slight changes in porosity, mainly in pore volume and especially in the average mesopore size. Morphological, textural and physicochemical characterizations of the new carbon and metal/carbon hybrid nanomaterials were also carried out in order to assess the influence of synthetic parameters on the resulting materials. This fast, simple and cost-effective photoassisted approach opens up interesting prospects in the synthesis of porous carbons and hybrid materials that could be used, for example, as photocatalysts in wastewater treatment and advanced oxidation processes.