One-pot EPD/ECD fabrication of high-performance binder-free nanocomposite based on the Fe_3O_4 nanoparticles/porous graphene sheets for supercapacitor applications

摘要

In this paper, we report one-pot fabrication of Fe_3O_4 nanoparticles electro-chemically decorated onto porous graphene nanosheets (PGNs) as high-performance nanocomposite for energy storage applications. In this regard, a novel and facile electrophoretic/electrochemical deposition (EPD/ECD) method was developed for the fabrication of binder-free high performance Fe_3O_4@PGNs/Ni foam. For comparison, pristine Fe_3O_4/Ni foam and PGNs/Ni foam electrodes were also fabricated via electrochemical and electrophoretic methods, respectively. The prepared materials were characterized by XRD, FT-IR, FE-SEM, TEM, TGA/DSC and BET techniques. The results confirmed co-deposition of Fe_3O_4 particles and porous graphene sheets onto the surface of Ni foam. The capabilities of the fabricated electrodes (i.e. Fe_3O_4/Ni foam, PGNs/Ni foam, Fe_3O_4@PGNs/Ni foam) were investigated as the binder-free electrodes for supercapacitor applications. The composite electrode showed specific capacitance as high as 892 F g~(-1) at the current density of 0.5 A g~(-1), where Fe_3O_4/Ni foam, PGNs/Ni foam electrodes exhibited only 312 F g~(-1) and 401 F g~(-1), respectively. Furthermore, the rate capability of the Fe_3O_4@PGNs/Ni foam electrode was found to be 73.2% as the current density increased to 10 A g~(-1), which was much higher than those of both pure Fe_3O_4/NF and PGNs/NF electrodes (i.e. 40% and 59%, respectively). In addition, the cycling stabilities of the composite electrode were measured to be 95.2% and 87.6% after 4000 successive charge/discharge cycles at the current densities of 2 and 5 A g~(-1), where the pristine Fe_3O_4/Ni foam exhibited capacity retentions of 81% and 67% at the current loads of 2 and 5 A g~(-1), respectively. The obtained results confirmed an outstanding performance of the fabricated Fe_3O_4@PGNs composite electrode as compared with single-component electrodes (i.e. Fe_3O_4/Ni foam, PGNs/Ni foam). These findings implicated the positive synergistic effects between Fe_3O_4 and porous graphene nanosheets to exhibit high supercapacitive performance.