Nuevos materiales de carbono para el almacenamiento y la producción de energía

Resumen

[EN] This work deals with the preparation and characterization of carbon materials that display a variety of structural characteristics by means of the templating technique and catalytic graphitization. Their behaviour as electrodes in electrochemical capacitors or as electrocatalytic supports is also studied. In the first part of the work mesoporous carbon materials were prepared by means of the templating technique. For this purpose, HMS mesostructured silica was used as template. The structural characteristics of the silica materials and, consequently, of the carbon materials were controlled by modifying the synthesis temperature of the silica and by carrying out hydrothermal post-treatment. Carbon materials prepared in this way are characterized by a high textural porosity (~ 50 % of total pore volume corresponds to the textural porosity) and a tunable pore size (~ 2 – 11 nm). Their behaviour as electrodes in electrochemical capacitors was studied. The results showed the influence of both the total surface area and oxygen content on their performance in an electrochemical capacitor. In the second part of the work graphitic mesoporous carbon materials were prepared by combining the templating and the catalytic graphitization techniques. A mesoporous silica xerogel was used as template and different non-graphitizing polymeric precursors were employed as carbon source (polyfurfuryl alcohol, phenolic resin and sucrose). In this case, the structural characteristics of the carbon materials were controlled by modifying the carbon precursor, the catalyst, the amount of catalyst used, the precarbonization temperature and the final carbonization temperature. The carbon materials obtained are characterized by an accessible porosity, a high surface area (up to ~ 1000 m2•g-1), a high pore volume (0.3 – 1.40 cm3•g-1), and a high proportion of graphitic structures. The final part of the work was focused on the preparation of graphitic carbon nanostructures (capsules, ribbons, coils and bamboo-like structures) by means of the catalytic graphitization technique. Different saccharides (with and without hydrothermal treatment), sawdust, iron (II) gluconate and cobalt (II) gluconate were used as carbon precursors. It was found that modifying the carbon precursor, catalyst, and carbonization temperature, materials of a different structural order (d002 = 0.336 - 0.344 nm, Lc = 5.8 – 16 nm y La = 9 – 42 nm) can be synthesized. Subsequently, these carbon materials were used as Pt electrocatalyst supports, and their efficiency as catalysts in the methanol electrooxidation was assessed.