Sonochemical synthesis of NiCo₂O₄/NRGO nanocomposite as a cathodic material for the electrochemical capacitor application

Abstract

In this work, a novel nanocomposite consisting of NiCo₂O₄/N-doped reduced graphene oxide was prepared. In the first step, ultrafine NiCo₂O₄ nanoparticles (4.4 nm) were synthesized by the sonochemical method. In the second step, graphene oxide was synthesized by modified Hummer methods and then reduced and N-doped (NRGO) by a chemical method using a mixture of hydrazine and ammonia solution. NiCo₂O₄/NRGO nanocomposite was produced using the dispersion of NRGO nanosheets and NiCo₂O₄ nanoparticles under ultrasonic radiation for 30 min. The structure, morphology, and composition of various samples were investigated using an adequate analytical characterization method. Electrochemical tests such as cyclic voltammetry and galvanostatic charge–discharge studies were done in a three-electrode system with 1.0 M Na₂SO₄ solution as the electrolyte for supercapacitive study of the samples. The results confirmed the excellent supercapacitive behavior of the nanocomposite and good stability during the charge–discharge cycle. The specific capacitance for the nanocomposite was calculated using a galvanostatic charge–discharge experiment which 618 F.g⁻¹ in current density of 4.0 A.g⁻¹.