In-situ preparation of Fe3O4/graphene nanocomposites and their electrochemical performances for supercapacitor

Fe 3 O 4 has a broad application prospect in electrode materials of supercapacitors due to its high theoretical specific capacitance, low cost, and environmental friendliness. However, its easy agglomeration property and low charge/discharge cycle stability limit its further application. In order to overcome these issues, the preparation conditions for Fe 3 O 4 nanoparticles with high specific capacitance were optimized. Then the Fe 3 O 4 was used as the feedstock to prepare the Fe 3 O 4 /graphene nanocomposites using solvothermal method for the in-situ reduction of graphene oxide and the combination of Fe 3 O 4 nanoparticles with graphene. The Fe 3 O 4 nanoparticles, graphene oxides and Fe 3 O 4 /graphene nanocomposites were characterized by X-ray diffraction (XRD), N 2 adsorption, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The capacitance and stability of these samples were obtained from charge/discharge curves and cyclic voltammograms. The results show that during preparation process, Fe 3+ ions could combine with the O-containing functional groups on the surface of graphene oxide to form Fe 3 O 4 nanoparticles, and the graphene oxide could be in-situ reduced to form graphene simultaneously. This could effectively prevent aggregation of Fe 3 O 4 and stacking of graphene as electrode materials. Moreover, the optimal conditions for preparing Fe 3 O 4 /graphene nanocomposites (BF24G60) are 60% of graphene theoretical percentage in Fe 3 O 4 /graphene nanocomposites, 205 °C of preparation temperature, and 24 h of reaction time. For the BF24G60 sample, it has excellent cycle stability (93% after 500 cycles) and specific capacitance (300 F/g at 0.4 A/g), which is higher than that of the single graphene (77 F/g) and Fe 3 O 4 nanoparticles (222 F/g).