Achieving high specific charge capacitances in Fe₃O₄/reduced graphene oxide nanocomposites

We report a facile approach to synthesize nanocomposites with Fe₃O₄ nanopaticles (NPs) attached to reduced graphene oxide (rGO) sheets by a solvothermal process, which combines the growth of Fe₃O₄ NPs and the reduction of GOs in one single step. These Fe₃O₄/rGO nanocomposites were further used to fabricate thin film supercapacitor electrodes by using a spray deposition technique without the addition of insulating binders. It was found that the Fe₃O₄/rGO nanocomposites showed much higher specific capacitances than that of either pure rGO or pure Fe₃O₄ NPs. We further carried out electrochemical characterization of the Fe₃O₄/rGO nanocomposites with different Fe₃O₄ :  rGO weight ratios (e.g. IFe₃O_4 : rGO) and showed that Fe₃O₄/rGO nanocomposites with IFe₃O_4 : rGO = 2.8 exhibited the highest specific capacitance of 480 F g⁻¹ at a discharge current density of 5 A ^g−1 with the corresponding energy density of 67 W h kg⁻¹ at a power density of 5506 W kg⁻¹. These Fe₃O₄/rGO nanocomposites also showed stable cycling performance without any decrease in the specific capacitance after 1000 charge/discharge cycles. © 2011 The Royal Society of Chemistry.