Enhancement of Electrochemical Capacitance of Silicon Nanowires Arrays (SiNWs) by Modification with Manganese Dioxide MnO2

Silicon nanowire arrays (SiNWs) were fabricated by one-step metal-assisted chemical etching process and modified with MnO2 nanoparticles by a chemical electroless method. Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), secondary ion mass spectroscopy (SIMS), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize the MnO2-modified SiNWs. It was noted that the amount of deposited MnO2 increases with increasing deposition time. Moreover, it was found that the deposition of MnO2 on the SiNWs electrode surface leads to an increase of charge and discharge capacitive current and capacitance. Indeed, MnO2–modified SiNWs presents the largest areal capacitance of 21.296 mF/cm2 which is 14 times larger than that of SiNWs/Si (1.55 mF/cm2) and an energy density of 1.66375 mWh/cm2 for a scan rate of 10 mV/s. Therefore, MnO2@SiNWs/Si nanocomposite is a promising material for the micro-supercapacitor technology.