Manganese hexacyanoferrate derived Mn3O4 nanocubes–reduced graphene oxide nanocomposites and their charge storage characteristics in supercapacitors

Abstract

Mn₃O₄–reduced graphene oxide (RGO) nanocomposites were prepared by chemical decomposition of the manganese hexacyanoferrate (MnHCF) complex directly on the graphene surface. XRD studies revealed the formation of crystalline hausmannite Mn₃O₄ nanocubes in the as-prepared nanocomposites without any heat treatment. The FE-SEM images showed the formation of Mn₃O₄ nanocubes on the graphene surface in the as-prepared nanocomposites. HR-TEM studies confirmed the homogeneous dispersion of ∼25 nm Mn₃O₄ nanocubes on graphene nanosheets. The amount of Mn₃O₄ nanocubes and graphene in the nanocomposites was estimated using TGA analysis from room temperature to 800 °C in air. The FT-IR and Raman spectroscopic analysis confirmed the functional groups in the nanocomposites and defects in graphene nanosheets in the nanocomposites. Cyclic voltammetry and galvanostatic charge–discharge experiments demonstrated a high specific capacitance of 131 F g⁻¹ in 1 M Na₂SO₄ electrolyte at a current density of 0.5 A g⁻¹ for the RGM-0.5 nanocomposite. A capacitance retention of 99% was observed for 500 charge–discharge cycles at a current density of 5 A g⁻¹, which conformed the excellent stability of the RGM electrodes. The prepared Mn₃O₄–RGO nanocomposites are promising for electrochemical energy storage.