On-pot fabrication of binder-free composite of iron oxide grown onto porous N-doped graphene layers with outstanding charge storage performance for supercapacitors

An effective one-step electrochemical method was developed to synthesize three-dimensional N-doped porous graphene/magnetite nanoparticles hybrid onto Ni foam (Fe3O4@3D-NPG/NF electrode). In this method, 3D nitrogen-doped porous graphene layers are electrophoretically deposited onto Ni foam, accompanied by the simultaneous in situ electrochemical deposition (ECD) of magnetite particles onto 3D-NPG layers. For comparison, Fe3O4 particles and N-doped graphene were separately deposited onto Ni foam, and pristine Fe3O4/NF and 3D-NPG/NF electrodes were fabricated. The structure, composition and morphology of the fabricated electrode materials were systematically characterized by XRD, FT-IR, FE-SEM, Raman, TEM, BET, and TGA/DSC techniques. The formation mechanism of Fe3O4@3D-NPG hybrid through EPD/ECD was proposed and described in detail. The charge storage capabilities of the fabricated electrodes were analyzed as the supercapacitor electrode. The results GCD tests revealed that Fe3O4@3D-NPG electrode is able to deliver specific capacity value of 715 F g−1 at 2 A g−1 and cycle life of 94.3% after 5000 GCD cycles, where the pristine Fe3O4/NF electrode delivered only specific capacity of 219 F g−1 and 77.6% capacity retention. These findings implicated the positive synergistic effects between Fe3O4 and 3D-NPG in the hybrid electrode to exhibit higher supercapacitive performance. This simple strategy could find practical uses in the large-scale fabricating Fe3O4@3D-NPG electrode.