Low Temperature Catalytic Pyrolysis for the Synthesis of High Surface Area, Nanostructured Graphitic Carbon

Abstract

High surface area graphitic carbons are of great interest in emerging applications including catalysis and energy storage because of the well-developed crystalline structure, high electronic conductivity and thermal stability, and satisfactory oxidation resistance at low temperature. We have developed the synthesis of porous graphitic carbon with a large and accessible surface area via synthesis of carboxyl-containing polymer particles, followed by ion exchange and pyrolysis at low temperature (850 °C). The evolution of the graphitic structure together with mesoporosity is temperature dependent, as revealed from the results of X-ray diffraction, transmission electron microscopy, and nitrogen sorption measurement. Specifically, the development of mesoporosity resulting from continuously catalyzed carbonization by the in situ formed cobalt nanoparticles can be clearly recognized. Further nitric acid oxidation leads to an increase of the pore volume due to the removal of cobalt nanoparticles and opening of closed pore entrances. Moreover, the use of silica as the isolating shell facilitates the formation of high surface area graphitic carbon. Magnetization measurements show that the graphitic carbon/cobalt composites exhibit ferromagnetic properties, and the cobalt nanoparticles are stable under air for more than 10 months without degradation of their magnetic properties.