Synthesis of graphene from asphaltene molecules adsorbed on vermiculite layers

The strategy to regularly arrange and join the polycyclic aromatic hydrocarbons of asphalt into graphene was explored. Expanded vermiculite with a multi-layered structure was used to adsorb asphaltene molecules onto its surfaces or into its interstices, and graphene sheets with 8–10 graphene layers and a width of tens of microns were obtained by carbonization of the regularly-arranged asphalt molecules. The formation of graphene layers is ascribed to not only the regular arrangement of asphaltene molecules due to the adsorption by vermiculite layers but also the joining of the asphaltene molecules catalyzed by the Fe-containing vermiculite surfaces. By the preabsorption of melamine on vermiculite, a nitrogen-doped graphene–carbon nanotube hybrid was produced from asphalt. As anodes for Li-ion batteries, the obtained graphene materials exhibited increased capacities and rate performance as compared to the widely-used reduced graphene oxide, indicating that the asphalt-derived graphene materials have a reasonable quality.