Synthesis of N-doped graphene aerogel/Co3O4/ZnO ternary nanocomposite via mild reduction method with an emphasis on its electrochemical characteristics

Abstract

In this study we report a tunable chemical method for the synthesis of nitrogen doped graphene aerogel decorated with Co3O4 and ZnO nanoparticles. The subtle synthesis method was based on the mild reduction graphene hydrogel (GH) whereas before reduction step, Co and Zn were adsorbed on graphene oxide (GO); this pre-adsorption step (at pH = 6) prevented the graphene sheets aggregation and provided favorable reduction conditions at next step of the synthesis process. Eventually, after freeze drying and heat treatment, the ternary composite aerogel was obtained. According to scanning electron microscopy (SEM), Co3O4 and ZnO nanoparticles were randomly dispersed on the graphene sheets due to the prior adsorption step. According to Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses, the synthesized N-doped graphene aerogel/Co3O4/ZnO ternary nanocomposite had a specific surface area and a pore volume of 215 m2 g−1 and 1.2 cm3 g−1, respectively. In addition, Fourier Transform Infrared (FT-IR) spectroscopy and X-Ray diffraction (XRD) were employed to evaluate the mechanisms of nanocomposite formation. Owing to the synergic effect of the nanocomposite constituents, the synthesized material exhibited a high specific capacitance (543 F g−1 at 1 A g−1), an excellent cycling stability (78.5% capacitance retention after 1000 cycles at 5 A g−1) and an adequate capacitive performance (74% capacitance retention by an increase in current density from 1 to 5 A g−1) with low internal resistance (about 0.007 V). The findings of this work present a promising candidate as a graphene based electrode material in supercapacitor devices.