Facile and ultrafast solid-state microwave approach to MnO2-NW@Graphite nanocomposites for supercapacitors

MnO2 nanowires/graphite nanocomposites (MnO2-NW@Graphite) were successfully manufactured by an ultrafast, facile and cost-effective solid-state approach using microwave energy. Intensive research was conducted to investigate the effects of the material mass ratio, the microwave power and the microwave exposure time on the yield and morphology of the MnO2-NW@Graphite nanocomposites. The effect of the heating layer on the morphology was also studied. The morphology and structure of the nanocomposites were characterized using scanning electron microscope (SEM), X-ray power diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA). In addition, the electrochemical performances of the MnO2-NW@graphite nanocomposites were evaluated in basic media using 1 M potassium hydroxide (KOH). The prepared nanocomposites exhibit a maximum specific capacity of 380.4 F/g at a current density of 1 A/g. The composites show high rate capabilities and good long-term stability with approximately 80% (303.57 F/g) retention of capacitance after 2000 cycles. With the low mass percentage (12.9%) of MnO2 nanowires in MnO2-NW@Graphite, its outstanding electrochemical performance shows that it is a promising electrode material for supercapacitors. In addition, this microwave assisted approach towards the fabrication of MnO2 nanowires is expected to achieve mass production for inexpensive energy materials.