High-Performance Hybrid Supercapacitors Based on Ce-Doped NiMoO₄ Nanosheets and Fe₃O₄@Bi₂O₃ Nanoarrays

Abstract

Doping metal ions into metal compounds is an effective strategy to improve ionic and electronic conductivity and electrochemical properties of metal compounds. Herein, we demonstrate the design and fabrication of novel Ce-doped NiMoO4 nanosheets by a simple hydrothermal method without adding any surfactants and templates toward achieving high-specific energy aqueous hybrid supercapacitors. The doping of Ce ions into the sheet structure of the NiMoO4 material can expand the tunnel structure of the crystal and enhance the electronic conductivity of the nanomaterials, thus providing the electrode material with a large ion storage space and easy ion diffusion channels. The Ce-doped NiMoO4 nanosheet shows a high specific capacity of 107 mA h g–1 at 1 A g–1, which is higher than that of the bare NiMoO4 nanosheet. In addition, a novel hybrid supercapacitor (HSC) is fabricated by using Ce-doped NiMoO4 nanosheets as the positive electrode and Fe3O4@Bi2O3 nanoarrays as the negative electrode, with aqueous KOH as the electrolyte. The Ce-doped NiMoO4//Fe3O4@Bi2O3 HSC has a high output voltage (1.65 V) and a high energy density of 32.8 W h kg–1 at a power density of 415 W kg–1 as well as good electrochemical stability. The results show that Ce-doped NiMoO4 nanosheets can be used as an advanced electrode for supercapacitors.