Magnetic Properties of Activated Carbon Fibers and their Iodine-Doping Effect

Abstract

Activated carbon fibers (ACFs) are microporous carbons consisting of a three-dimensional disordered network of micrographites. In order to clarify the correlation between the disordered structure and the electronic properties, we investigated the magnetic susceptibility of heat-treated and iodine-doped ACFs. The heat treatment reduced the Fermi energy of ACFs, but the carrier density per micrographite estimated from the Fermi energy is nearly equal to the density of dangling bond spins of as-prepared ACFs, irrespective of heat treatment temperature. In less graphitized ACFs, a charge transfer arises from ACFs to iodine, suggesting less graphitized micrographite has the electronic features of condensed polycyclic aromatic hydrocarbons. On the other hand, well graphitized micrographites in ACFs, are more graphitic in their electronic state, resulting in the absence of charge transfer to iodine.