Xerogeles de carbono como soporte de catalizadores para pilas de combustible de carbono

• Autores: Cintia Alegre Gresa
• Directores de la Tesis: María Jesús Lazaro Elorri (dir. tes.), Rafael Moliner Alvarez (dir. tes.)
• Lectura: En la Universidad de Zaragoza ( España ) en 2014
• Idioma: español
• Tribunal Calificador de la Tesis: Miguel Menendez Sastre (presid.), Ana Arenillas de la Puente (secret.), David Fermín (voc.)
• Materias:
  • Física
    • Física atómica y nuclear
      • Conversión de energía
  • Química
    • Química inorgánica
      • Carbono
• Enlaces
  • Tesis en acceso abierto en:  Zaguán  Digital CSIC 
• Resumen

  • [EN]Carbon gels are porous materials with a reticular structure formed by interconnected spherical carbon nanoparticles. The versatility of their properties in terms of structure, form and texture favors their application in many fields: catalysis, energy conversion and storage, etc. The work presented herein deals with the study of the influence of synthesis conditions on the properties of carbon xerogels (CXGs). The study analyzes the effect of the composition of the mixture of carbon gel precursors and the pH, on the porous structure, the arrangement of carbon, the surface chemistry and the electrical conductivity. Certain conditions allow to obtain CXGs with a high porosity and a high degree of cross-linking. CXGs composition has been modified by the introduction of various heteroatoms: O, N and S, by oxidation, doping and vulcanization, respectively. Such treatments strongly bind these heteroatoms to the carbon surface, modifying properties such as their ordering degree, surface chemistry, electrical conductivity and porosity. Subsequently, the study focuses on the use of CXGs as electrocatalyst support for fuel cells. These kinds of devices directly and efficiently convert the chemical energy of a fuel to electrical energy, which has caused an increasing interest in research and development. The electrocatalysts, based on platinum supported on carbon, are responsible of this energy conversion electrochemical process. The use of carbon xerogels as electrocatalytic support is advantageous given that improves the diffusion of reactants and products. In this work, the effect of CXG as support for Pt on the electrocatalytic activity has been investigated. The support properties determine the catalyst features. The use of CXGs with high porosity as electro-catalytic support is advantageous due to the improvement of the diffusion of reactants and products, for both the methanol oxidation reaction and the oxygen reduction reaction (ORR).Changing the composition of CXGs, particularly with S and N, increases the electrocatalytic activity of catalysts, particularly for the ORR. Both CXGs and catalysts were subjected to accelerated degradation processes, noting that it is preferable to use CXGs with intermediate porosities to obtain catalysts more resistant to degradation, at the expense of a slightly lower activity.