Band gap modified boron doped NiO/Fe3O4 nanostructure as the positive electrode for high energy asymmetric supercapacitors

A boron doped NiO/Fe3O4 nanostructure was successfully synthesized by a facile one-step hydrothermal method. The boron doping was confirmed from the decreased band gap and increased electrical conductivity of the NiO/Fe3O4 composite. The Nyquist plot of the multimetal oxide was fitted with ZView software for detailed understanding of the effect of concentration of different metal oxides, boron doping and extensive charge-discharge cycles on the electrochemical properties of electrode materials. Very high specific capacitance of similar to 1467 F g(-1) was achieved as the synergistic effect of low activation energy and short ion diffusion path of the electrode materials. An asymmetric supercapacitor (ASS) was fabricated with the NiO/Fe3O4 composite and thermally reduced graphene oxide as the positive and negative electrode, respectively. The ASS showed a large specific capacitance of similar to 377 F g(-1) at a current density of 3 A g(-1). Furthermore, the ASS showed a large energy density of similar to 102.6 W h kg(-1) and huge power density of similar to 6300 W kg(-1) and remained similar to 82% stable even after 10 000 charge-discharge cycles. Therefore, a facile hydrothermal method was demonstrated to enhance the electrochemical properties of a multimetal oxide by boron doping for the development of next generation energy storage devices.