Design 3D hierarchical flower-shaped NH4V4O10/N-GQDs/cellulose nanocomposites as electrode materials for supercapacitor application

In recent years, materials based on carbon dioxide compounds and transition metal oxide nanocomposites with desirable synergistic properties have attracted a great deal of attention as potential candidates for high efficiency electrochemical supercapacitors. Our work presents the development of high-performance supercapacitor electrodes using the 3D-flower-shaped NH4V4O10 microstructures combined with nitrogen-doped graphene quantum dots and cellulose (NHV-NGC). A simple in-situ hydrothermal synthesis was used to synthesize the NHV-NGC. Various methods are employed to characterize the physiochemical properties of the synthesized composite. In addition, cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) were used to examine the electrochemical behavior of the materials as designed. According to the GCD profiles, the optimized NHV-NGC electrode has a specific capacitance of 1852.9 Fg-1 (878 Cg-1) at a current density of 2 Ag-1 in 3.0 M KOH aqueous electrolyte. As well, the specific capacitance of the NHV-NGC electrode is about three times greater than the specific capacitance of the NHV electrode (631 Fg-1 (300 Cg-1). The electrode shows a high retention specific capacitance of 83.5% after 3,000 charge-discharge cycles at a scanning rate of 100 mVs-1. Additionally, the fabricated supercapacitor exhibits an energy density of 57.8 Whkg-1 at a power density of 473.9 Wkg-1. Based on the GCD plots of the optimized NHV-NGC electrode, the specific capacitance was calculated to be 1852.9, 1224.9, 981.8, and 286.2 Fg-1 (878, 587.1, 466, and 137.1 Cg-1) at 2, 3, 4, and 5 Ag-1, respectively. Synergistic effects between the three-dimensional flower-shaped NH4V4O10 microstructures, nitrogen-doped graphene quantum dots and cellulose in the nanocomposites structure resulted in extraordinary conductivity, excellent electrochemical performance, and the development of suitable routes for rapid ion/electron transport via reversible redox reactions. In terms of electrochemical performance, the NHV-NGC nanocomposite is proving to be a promising candidate for energy storage devices such as supercapacitors.