Hydrothermal synthesis, characterization and electrochemical behavior of NiMoO4 nanoflower and NiMoO4/rGO nanocomposite for high-performance supercapacitors

Abstract

The morphology of NiMoO4 plays a key role in enhancing the specific capacitance of supercapacitors. Generally a morphology that offers high surface area and thin electrolytic dielectric characteristic is vital. In the present study, NiMoO4 nano flower and NiMoO4/rGO (2.5, 5.0, and 7.5%) nanocomposites were synthesized by hydrothermal method and characterized by analytical methods. Their electrochemical behavior was examined by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) techniques. The fabricated electrodes with both the materials showed pseudocapacitive behavior due to their Faradic redox properties between 0.0 to 0.5 V. NiMoO4 and NiMoO4/rGO yielded specific capacitance of 1092 and 1400 F g−1, respectively at a current density of 1 A g−1. Their Electron Impedance Spectra exhibited impedance of 1.6 and 1.4Ω for NiMoO4 and NiMoO4/rGO nanoflower, respectively. The difference in the specific capacitance and electrochemical impedance for both the electrode materials is due to added rGO. The study of cyclic stability showed retainment of 88% of the original specific capacitance by NiMoO4nanoflowerand 91% by NiMoO4/rGO nanocomposite for 2000cycles at 20 A g−1, thus illustrating excellent electrochemical stability. So, it is evident that both NiMoO4nanoflower and NiMoO4/rGO nanocomposite could be convenient choices as electrode materials for the fabrication of commercial supercapacitors in the future.