Graphene quantum dots decorated on spinel nickel cobaltite nanocomposites for boosting supercapacitor electrode material performance

Highlights: • An efficient composite electrode material (NiCo₂O₄/GQDs) was developed with enhanced conductivity and high energy density. • A facile hydrothermal method was used to synthesize NiCo₂O₄/GQDs composite; while NiCo₂O₄ was prepared by sol-gel technique. • The observed specific capacitance of the fabricated composite was found to be 481.4 Fg^-1 at 0.35Ag^-1 is higher than GQDs. • NiCo₂O₄/GQDs composite based electrode material will be a promising substitute material for next generation super capacitor -- Abstract: Composites of transition metal oxides, with carbon, have been considered to be appropriate materials for enhancing their electrochemical properties in supercapacitor applications. In this study, we prepare Nickel-Cobaltite/ Graphene Quantum Dots (NiCo₂O₄/GQDs) composite structures that exhibit improved electrical conductivity and function as electrode materials with higher energy density in comparison to GQDs and NiCo₂O₄. The electrochemical performance of NiCo₂O₄/GQDs is confirmed through galvanostatic charge–discharge method for three electrode systems with an electrolyte of 0.1 M potassium hydroxide. The observed specific capacitance for the fabricated composite has been found to be 481.4 Fg⁻¹ at 0.35Ag⁻¹. It is higher than that of Graphene Quantum Dots (C_sp~45.6 Fg⁻¹). This is due to the enhancement in the electrical conductivity and diffusion of ions which become faster between electrodes and electrolyte. These findings demonstrate the unique characteristics of the fabricated composites as superior electrode materials for applications in supercapacitors.