In situ growth of monodisperse Fe3O4 nanoparticles on graphene as flexible paper for supercapacitor

Abstract

A well-organized Fe₃O₄/graphene sheet composite (GS/Fe₃O₄) paper has been constructed via a universal three-step method. A graphene oxide/Fe₂O₃ composite (GO/Fe₂O₃) dispersion is prepared followed by vacuum filtration of the dispersion to obtain a GO/Fe₂O₃ composite paper. Finally, heat treatment of the GO/Fe₂O₃ paper produces the GS/Fe₃O₄ paper. Fe₃O₄ nanoparticles of ∼5 nm are grown in situ and uniformly anchored on graphene sheets by covalent chemical bonding. The three-dimensional (3-D) conductive paper provides good electrical contact and improves the dispersion of well-adhered Fe₃O₄ nanoparticles, further boosting the accessible capacity. Therefore, the GS/Fe₃O₄ paper exhibits excellent rate performance and cyclic stability as a flexible anode material for supercapacitors. The optimized GS/Fe₃O₄ paper could achieve a high specific capacitance of 368 F g⁻¹ at 1 A g⁻¹ and remain 245 F g⁻¹ at 5 A g⁻¹ after 1000 cycles, suggesting a promising application in the fabrication of flexible energy storage devices. This work opens up new insights into the design of GS/metal oxide paper as a flexible electrode.