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 MnO 2 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 MnO 2 -modified SiNWs. It was noted that the amount of deposited MnO 2 increases with increasing deposition time. Moreover, it was found that the deposition of MnO 2 on the SiNWs electrode surface leads to an increase of charge and discharge capacitive current and capacitance. Indeed, MnO 2 –modified SiNWs presents the largest areal capacitance of 21.296 mF/cm 2 which is 14 times larger than that of SiNWs/Si (1.55 mF/cm 2 ) and an energy density of 1.66375 mWh/cm 2 for a scan rate of 10 mV/s. Therefore, MnO 2 @SiNWs/Si nanocomposite is a promising material for the micro-supercapacitor technology.