Expanded Graphite - Carbon Nanotubes Nanocomposite Materials

Abstract

Here, we explain the method of obtaining the expanded graphite-multiwall carbon nanotubes nanocomposite, give its structural and mechanical characteristics important for application, and, based on quantum chemical calculations, propose a mechanism for the formation of a chemical bond between oxidized graphene-like planes. Synthesis of expanded graphite-carbon nanotubes without binders consists in simultaneous deagglomeration of carbon nanotubes and intercalation of natural graphite. This procedure was carried out in two variants: electrochemical (anodic) oxidation and chemical oxidation. Graphite oxidized to the first stage (blue) was hydrolyzed, washed to neutral pH, dried, and heat-treated at a temperature of ~1000°C in a gas horizontal industrial furnace. The resulting expanded graphite powder was rolled on horizontal rolls. X-ray photoelectron spectroscopy was used to determine the amount of oxygen and the type of oxygen-containing groups on the surface of expanded graphite and carbon nanotubes and the dependence on the amount of electricity passed during anodic oxidation. Features of the structure of expanded graphite obtained by various methods and composite expanded graphite-multi-walled carbon nanotubes were investigated by Raman spectroscopy. The energy effects of the interaction of partially oxidized graphene-like planes with each other and their dependence on the nature of the oxygen-containing functional groups present in them and on the dimensions of the graphene-like planes themselves were clarified by quantum chemistry methods. It was established that the most thermodynamically probable is the reaction between the hydroxyl and aldehyde groups of two interacting graphene-like planes, regardless of their sizes.