A study of one-dimensional α-MnO2/ZnO binary nanocomposite as a beneficial electrode material for supercapacitor application and its charge transport mechanism

In this present work, one-dimensional alpha-MnO2/ZnO (MZ) binary nanocomposite were synthesised via a hydrothermal process. The crystal structure as well as the average crystallite size was found to be 33, 43 and 37 nm for pure alpha-MnO2, ZnO and MZ respectively as assessed through X-ray diffraction analysis. The functional groups, vibrational mode of molecules, surface area, morphology, and elemental composition of the prepared samples was determined through Fourier transform infrared spectroscopy, Raman spectroscopy, BET, HR-SEM, and EDX analysis. HR-SEM analysis revealed alpha-MnO2 nanowires and ZnO nanorods with a diameter of 70 and 202 nm respectively. Through Cyclic Voltammetry, Galvanostatic charge/discharge and Electrochemical impedance spectroscopy studies, the electrochemical behaviour of the synthesised active electrode material with a 2 M Na2SO4 electrolyte were examined. In terms of overall performance, the MZ electrode achieved a specific capacitance of 494 F g-1 at a current density of 1 A g-1. Furthermore, MZ binary nanocomposite demonstrated a promising cyclic retention of 86.2 % over 3000 cycles. The enhanced electrochemical performance of binary composites is primarily due to their well-designed one-dimensional nanostructure, which provides a significantly larger surface area and beneficial synergistic impact on the active electrode. The ac conductivity and correlated barrier hopping (CBH) charge transport mechanism was observed in the temperature range of 303 K <= T <= 393 K and in the frequency range of 4 Hz <= f <= 8MHz. These results suggest that the synthesised MZ nanocomposite is a potential material for energy storage applications.