Abstract
Manganese oxide nanowire mixture is successfully prepared by two electrode pulse-rest method with different pulse time and rest time. All of conditions show good capacitor behavior by cyclic voltammetry in both monovalent and bivalent mild solution, and the specific capacitance is between 41~157 F/g. The largest data from this study is obtained in 1.1V pulse voltage, 0.5s pulse time, 0.5s rest time, and working in 0.5M calcium chloride solution. The surface morphology was obtained by field emission scanning electron microscope (FE-SEM), which aspect ratio was affected by the pulse parameter, and the detail morphology and crystalline species are confirmed by high resolution transmission electron microscope (HR-TEM). Finally, the oxidation state is obtained by X-ray photoelectron spectroscope (XPS) and Raman spectrum. The cation effect is observed by electrochemistry quartz crystal microbalance (EQCM). On the other hand, the pulse parameters also affected the different capacitor behavior in monovalent and bivalent electrolyte. In our study, we assume that the ton/toff ratio, could affect the capacitor behavior in monovalent and bivalent electrolyte. The charge/discharge reaction can be summarized as: MnO2+δM+ + δe− □ MnO2−δ (OM)δ Finally, we deposited manganese oxide by galvanostatics by using the pulse oxide, pure Mn3O4 crystalline, and MWCNT (multiwall carbon nanotube) as the substrate. The manganese oxide mixture also shows good capacitance, power density, and reversibility. Moreover, the mixture shows excellent stability in 0.5M Na2SO4 electrolyte: only 5~15% decay during 10000 cycling, and the maximum specific capacitance value is 390.8F/g.