Preparation Of MnO₂/TiO₂ Nano-heteroj Unction And Investigation On The Performance Of Supercapacitor

The supercapacitor is a novel green energy storage device different from the battery and conventional capacitor, with features of high charge-discharge efficiency, high power output and a long service life. It shows broad application prospect in the field of electric vehicles and mobile communications. It also can be used as electronic component, as well as DC converter power generator. Therefore the research attracted much attention in the recent years. Lately, manganese dioxide which is abundant in reserves and cheap in price has become one of the most promising electrode materials for the supercapacitor because of its excellent capacitive performance in the moderate electrolyte. And manganese dioxide with various morphologies have been prepared by hydrothermal synthesis, template, sol-gel method, etc.In this paper, manganese dioxide is deposited on highly ordered titanium nanotubes to prepare materials of supercapacitor by electrodeposition and hydrothermal synthesis. TEM、XRD、FESEM and XPS are used to characterize the phase and morphology of MnO2/TiO2 heterojunction. And the cyclic voltammetry and charge-discharge tests were also carried out to analyze the influence of voltages on the morphology and supercapactive performance of MnO2/TiO2 heterojunction, research the connection between the morphology and supercapactive performance. The main research follows:MnO2/TiO2 heterojunction is prepared by the potentiostatic deposition on TiO2 nanotube arrays. The different voltages of 0.6 V,0.9 V,1.2 V,or the different concentration of 0.01 mol/L,0.05 mol/L,0.1 mol/L,0.15 mol/L,0.2 mol/L, or the different time of 120 s, 600 s,900 s,1200 s, are taken in different experiments to study the influence of the parameters on the morphologies and supercapactive performance of MnO2/TiO2 heterojunction. The final results show that best performance of MnO2/TiO2 heterojunction is obtained when needle-MnO2 grains and TiO2 nanotubes are fully integrated, at the voltage of 0.6 V, the concentration of 0.05 mol/L and the time of 600 s. The best specific capacitance is 51.6 mF/cm2 at the scan rate of 10 mV/s.After that, the MnO2/TiO2 heterojunction is prepared by hydrothermal synthesis on TiO2 nanotube arrays at the manganese acetate concentration of 0.01 mol/L,0.05 mol/L, 0.1 mol/L,0.2 mol/L. The TiO2 nanotubes are immersed in the solution and putted into the reactor. Finally the reactor is putted into a thermostatic electric blast oven for 2 h at the temperature of 90℃. As a result, the best performance MnO2/TiO2 heterojunction is obtained at the concentration of 0.05 mol/L. The best specific capacitance of 79.7 mF/cm2 is obtained at the scan rate of 10 mV/s and 159.4 F/g at the current density of 1 A/g.