NiO nanoparticles and their nanohybrid with flat rGO sheets: As an ideal electroactive material for hybrid capacitor applications

Abstract

Extensive research on electrode materials has revealed that the nature, structure, surface area, and conductivity of the electrode material largely control the overall performance of the electrochemical capacitor (ECC). Herein, we prepared homogeneous sized NiO nanoparticles (NPs) via a surfactant-assisted wet-chemical technique and ultrasonically mixed with 2% and 4% rGO for ECC applications. The surface area, conductivity, and specific capacity of the NiO@rGO nanohybrid had been improved by graphene nanosheets, making the nanohybrid appropriate for ECC applications. Our NiO@rGO nanohybrid electrode with 4% graphene content demonstrated a high specific capacity of 883 Cg-1 at 05 mVs−1 and a superior rate capability of 72.64% at 100 mVs−1. Furthermore, following 3500 cycle testing at 100 mVs−1, the NiO@rGO nanohybrid (with 4% rGO) based electrode shows a minimum capacity loss of 7.3%, confirming its outstanding cyclic stability. In the light of impedance studies, the charge transfer, equivalent series, and diffusion resistance values were at their lowest for a nanohybrid sample with 4% rGO, indicating a fast redox reaction at the NiO@rGO/electrolyte interface. The exceptional electrochemical presentation of the NiO@rGO sample is ascribed to its good conductivity, a large number of active sites at the surfaces, and facile electrolyte diffusion into the structure due to the well-organized nanostructured constituents. Our surfactant-assisted and ultrasonically manufactured synthesized NiO@rGO nanohybrid sample offers a broad application promise in hybrid capacitors because of its beneficial integrated properties.