Facile synthesis of a MnFe2O4/rGO nanocomposite for an ultra-stable symmetric supercapacitor

Abstract

In this paper, a binary MnFe₂O₄/reduced graphene oxide (MnFe₂O₄/rGO) nanocomposite is successfully synthesized using a facile approach. To possess larger layer spacing, worm-like expanded graphite (EG) is used instead of graphite for the synthesis of pristine graphene oxide (GO) suspension using the modified Hummer's method. Furthermore, the obtained GO suspension concentrated by Mn²⁺ ions is utilized to synthesize the MnFe₂O₄/rGO nanocomposite by precipitation of Mn²⁺ ions and in situ reduction of GO, simultaneously. The formation of the MnFe₂O₄/rGO nanocomposite and its individual constituents is confirmed using XRD, FT-IR, Raman, FE-SEM, TEM, BET, and TGA. Moreover, the magnetic properties of the samples are studied using a vibrating sample magnetometer. A hybrid supercapacitor is fabricated using a two-electrode system with a synthesized nanocomposite that demonstrates the specific capacitance of 271 F g⁻¹ at the current density of 0.5 A g⁻¹ in 6 M aqueous KOH electrolyte. It is worth noting that the cycling durability of the symmetric supercapacitor is excellent, in which 104% of primary capacitance is preserved after about 5000 periods. Thus, the obtained extraordinary electrochemical proficiency of the binary composite is a result of the specific construction and the qualified electrical conductivity of the rGO nanosheets.