Novel Carbon-Based Host—Guest Systems

Abstract

Carbon-based materials such as graphite and microporous carbon provide spaces for the accommodation of “guest” materials. In graphite, the galleries between graphitic sheets form a two-dimensional nanospace available for the guest materials, while guests are accommodated in the micropore network having a random structure in the microporous carbon systems. It is expected that the guest materials in these micropore spaces having restricted geometry and dimensionality, form different structures from the structures of the ordinary bulk states. Moreover, the guest materials geometrically confined in the micropore space provide novel solid state properties related to their peculiar structures. We design the novel carbon-based host—guest systems from the point of structure and electronic properties, with the employment of light element guest materials such as He, H2 and O2 in alkali-metal-graphite intercalation compounds and microporous activated carbon fibers. In this paper, we present the studies on the two-dimensional metallic hydrogen and oxygen formed in the graphitic nanospace and the remarkable condensation of helium atoms in ultra-micropores of microporous carbon.