3D graphenic microporous carbon from zeolite template

Abstract

Three-dimensional (3D) graphenic porous carbon has garnered considerable interest as an attractive material for various applications due to the characteristics of graphene combined with a 3D porous structure. Recently, the synthesis of such carbons has been investigated using zeolite as a template. The porous structure of zeolite is suitable for the formation of 3D interconnected single layer graphene without the stacking problem. However, zeolite has narrow micropores that are too small to accommodate large molecular compounds. Small hydrocarbons, such as acetylene and ethylene, therefore have been widely used for carbonization within the zeolite micropores. Carbon synthesis with small hydrocarbon molecules requires high carbonization temperature, inducing non-selective carbon deposition on the external surface of the zeolite. In this thesis, lanthanum-catalyzed synthesis was explored to resolve the problem of zeolite-templating synthesis. The catalytic carbonization occurred at a low temperature, preventing external carbon deposition on the surface of zeolite crystals. X-ray diffraction analysis using single crystal revealed that the resultant carbon had a 3D graphene-like interconnected porous structure. The 3D graphene-like microporous carbon exhibited high conductivity and an ordered microporous structure originated from the zeolite template. Furthermore, the lanthanum-catalyzed synthesis can be applied to small-pore zeolites, which were considered an inadequate template for carbon replication. The resultant carbon had an ordered array of ultramicropores, where the ultramicropore diameter corresponded to the zeolite wall thickness.