Massive-exfoliation of magnetic graphene from acceptor-type GIC by long-chain alkyl amine
Graphene can be prepared from a graphite intercalation compound (GIC) with acceptor-type intercalator, FeCl3. When the FeCl3–GIC is treated with primary amines at 90 °C for 6 h, the GIC expands to a few layers. The expansion is further facilitated, as the alkyl chain of primary amines becomes longer, while tertiary amines cannot penetrate inside the GIC because of their structural steric hindrance. The primary amine adsorbed in the GIC is oriented to form a bilayer by an indirect reactions among FeCl3–graphene–amine, and this process plays an important role in the expansion of the GIC, in contrast to the reaction of primary amines with donor-type GICs. Then the expanded-GIC is sonicated to exfoliate the graphene sheets. The obtained material exhibited a superparamagnetic property due to the remaining iron compounds. This approach using FeCl3–GIC and primary amine is preferable for the mass production of graphene because of the mild reaction conditions and the short treatment time for exfoliation from the chemically stable FeCl3–GIC. Moreover, the magnetization of graphene nano-composites could be useful for magnetic-recovery processes, electromagnetic heating, and the other applications.