Achieving high specific charge capacitances in Fe₃O ₄/reduced graphene oxide nanocomposites

We report a facile approach to synthesize nanocomposites with Fe ₃O₄ nanopaticles (NPs) attached to reduced graphene oxide (rGO) sheets by a solvothermal process, which combines the growth of Fe ₃O₄ 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 Fe ₃O₄/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 Fe ₃O₄/rGO nanocomposites with different Fe₃O ₄: rGO weight ratios (e.g. IFe₃O₄:rGO) and showed that Fe₃O₄/rGO nanocomposites with I _Fe3O4: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 Fe₃O ₄/rGO nanocomposites also showed stable cycling performance without any decrease in the specific capacitance after 1000 charge/discharge cycles.