One-step electrochemical synthesis of FTO/MnO2-graphene composite for electrochemical energy storage

Abstract

The FTO/MnO2-Graphene composite was prepared using a one-step electrochemical approach employing chronoamperometry. Graphene was synthesized via electrochemical exfoliation and characterized using Raman spectroscopy and transmission electron microscopy (TEM).The prepared composite film exhibiting an extraordinary structure offers a large surface area provided with several channels to enhance the rapid diffusion of ions and electron transport owing to the grapheme sheets content. Various characteristics of the composite films have been investigated through X ray diffraction (XRD). Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM) and UV–Vis spectroscopy. To evaluate the electrochemical performance of the FTO/MnO2 and FTO/MnO2-GR films, cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge tests were conducted. The specific capacitance was found at 5 mV·s−1, to be 192.3 F g−1 with graphene and 73.5 F g−1 without. This increase in capacitance upon incorporating grapheme sheets suggests that FTO/MnO2-GR composite film would have many potential applications as suitable materials for supercapacitor electrodes and energy storage devices. The FTO/MnO2-GR in a asymmetric supercapacitor demonstrated an excellent reversible operation, delivering an energy density of 3 W h kg−1 at a specific power of 25 W/ kg. Furthermore, even after 1000 cycles, the FTO/MnO2-GR asymmetric supercapacitor retains an impressive 99 % of its capacitance.