A new protocol for the distribution of MnO ₂ nanoparticles on rGO sheets and the resulting electrochemical performance

Herein, reduced graphene oxide (rGO)/MnO ₂ hybrid materials were prepared via a direct redox reaction between MnCl ₂ and KMnO ₄ on reduced graphene oxide (rGO) _. A systematic study was carried out to understand the role of KMnO ₄ . The morphology and microstructure of the as-prepared composite was characterized using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman Spectroscopy. Results indicate that the concentrations of KMnO ₄ have a detrimental effect on the distribution of MnO ₂ nanoparticles on rGO sheets and hence on electrochemical properties. The electrochemical capacitive behavior of the as-prepared composite was investigated using cyclic voltammetry (CV), galvanostatic charge discharge, and electrochemical impedance spectroscopy (EIS) in 1 M Na ₂ SO ₄ aqueous electrolyte solution. At the optimum concentration of KMnO ₄ , the as-prepared rGM-1 composite shows a high specific capacitance of 366 F/g at a scan rate of 10 mV/s. The composite also exhibits good electrocatalytic activity towards the oxidation of dopamine (DA), exhibiting a low detection limit of 2.3 × 10 ⁻⁷ M with a wide linear range between 2.5 × 10 ⁻⁷ M and 2.30 × 10 ⁻⁴ M. Hence, the use of rGO/MnO ₂ at an optimized concentration of KMnO ₄ is a potential competitive candidate in supercapacitor and biosensor applications.