Towards highly electrically conductive and thermally insulating graphene nanocomposites: Al₂O₃-graphene

Highly electrically conductive materials with low heat transfer rates are of very high importance for high temperature fuel cell technologies and the refractory material industry. We aim to develop such materials with high electrical conductivities/high thermal resistivities by creating composite materials of graphene and Al₂O₃. Here we describe a novel and facile method for the synthesis of Al₂O₃-graphene composites. Graphite oxide, which was prepared by the Hofmann method, was reduced by active hydrogen generated by the reaction of aluminum with a solution of sodium hydroxide. This reaction led to the formation of a nanocrystalline composite of graphene and aluminum hydroxide. The Al(OH)₃-graphene composite was then calcined and pressed into pellets. Sintering of the pellets yielded a nanostructured Al₂O₃-graphene composite. We characterized the properties of the Al(OH)₃-graphene and Al ₂O₃-graphene composite materials in all steps to get an understanding of the process of the nanocomposite formation. The materials were analyzed by XRD, high resolution XPS, Raman spectroscopy, SEM, SEM-EDS, STEM, STA and AFM. The resistivity and thermal conductivity of the final Al ₂O₃-graphene composite were measured. The Al ₂O₃-graphene nanocomposite is a promising conductive material for high-temperature applications.