Superparamagnetic Fe3O4 nanocrystals@graphene composites for energy storage devices

In this paper, a Fe3O4 nanocrystals@graphene composite (FGC) was synthesized via a chemical deposition method by using graphene oxide as a precursor. We also investigate the structures, physicochemical properties and applications of FGCs, involving superparamagnetic performance, and use as supercapacitors and lithium ion battery (LIBs). The results showed that the Fe3O4 NCs were formed and incorporated onto the surface of the graphene sheets. The composite material FGC with a micrometre scale structure possessed similar size as the graphene sheets and exhibited superparamagnetic behavior at room temperature. The supercapacitance values of the FGC composites were enlarged compared with those of the graphene sheets or Fe3O4 NCs, which is attributed to the interaction between the Fe3O4 NCs and the graphene sheets. Meanwhile, a superior rechargeable stability of FGCs used as an anode material in LIBs can be observed.