| Electrochemical capacitor also can be called supercapacitor. In recent years, supercapacitors are attracting great attentions over the world due to their high capacitance and potential applications in electronic devices. The research of supercapacitors is mostly focused on both high performance electrode materials and preparation of electrodes. So many researchers pay more attention to the metal oxides in order to get higher capacity. Metal oxides, such as Ru oxide, Ir oxide, and Mn oxide, have been attracting great interest due to their high gravimetric and volumetric capacitances. Recently, manganese oxide electrode has been extensively used as electrode material in the redox pseudocapacitor because of its abundance, low cost, diverse crystallographic structures and environmental friendliness. Application is in energy storage device.Many researchers were synthesized with different method with good capacitive super capacitors electrode material of manganese oxide. Oxidation manganese used as super capacitor electrode materials mainly points two kinds:one kind is manganese oxide film, one kind is preparation of electrodes. Use different methods can get the morphology of prepared the different structures of the manganese oxide, and different morphology structure in super capacitors manganese oxide performance also different. In capacitance Manganese dioxide usable chemistry and electrochemical method preparation. Among these manganese dioxide is an important electrode material for supercapacitor studies that exhibits diverse crystallographic structures in industrial electrolyses. MnO2 can be prepared by chemical as well as electrochemical methods.In the present work, By a variation in experimental conditions of synthesis, the crystallographic nature of MnO2 can be controlled. Electro-oxidation of Mn2+ to MnO2 by cyclic voltammetry in acidic electrolytes producesγ-MnO2. This is known as electrolytic manganese dioxide which is widely used as the cathode material in aqueous primary batteries. Electrosynthesis in neutral electrolytes leads to the formation ofδ-MnO2, which is less widely studied thanγ-MnO2. MnO2 is a very interesting and attractive material because it is diverse in crystalline structure. By a variation in experimental conditions of synthesis, the crystallographic nature of MnO2 can be controlled. An electrochemical quartz crystal microbalance is a very sensitive equipment, which tests quality. The surface quality change vibration electrode fits into quartz crystal oscillator circuit output signals of the frequency variation, according to Sauerbrey equation through the electrode surface frequency changes can work out quality changes. At corresponding mass increase is 131.61μg in a neutral medium. At corresponding mass increase is 42.27μg in an acidic medium. The mass of MnO2 exhibits faster growth in a neutral medium than in an acidic medium. The dates show that the electrolyte is an important influence factors of electro-oxidation of Mn2+ to MnO2 by cyclic voltammetry. It indicates thatδ-MnO2 is a more appropriate material for electrochemical supercapacitors thanγ-MnO2.In a MnO2 world, this little tiny octahedral enables the buildup of a colorful and diverse world, in which every version is just one combination of MnO6 octahedral. MnO6 octahedral can share vertices and edges to from endless chains MnO6 octahedral subunits, which can in turn be linked to neighboring octahedral chains by sharing corners or edges. In the nature, these tunnels of can befilled with water molecules and hydrogen. In the present work, Capacitance studies ofδ-MnO2 in the 0.1 M Na2SO4 electrolyte are accompanied by mass variations reflecting insertion/ deinsertion of solution species. The mass ofδ-MnO2 is 199.7μg before subjecting the crystal in 0.1 M Na2SO4 solution. During the forward sweep starting, there is a gradual decrease in mass which is 12.10μg. In the reverse direction of the sweep,mass gains gradually to nearly its initial value. Reversible insertion/deinsertion of hydrogen is studied.For electrochemically prepared MnO2, Electro-oxidation of Mn2+ to MnO2 by cyclic voltammetry on gold in neutral electrolytes is studied using EQCM. The EQCM, in tandem with the electrode voltage during deposition, has been used to characterize features of the deposition mechanism and the porosity of the resultant manganese dioxide deposit as a function of crystal nucleation. At corresponding pH value decrease is 3.95μg in a neutral medium. In the reverse direction of the sweep, mass gains gradually to nearly its initial value. It indicates that insertion/deinsertion of hydrogen is studied in MnO2 surface. |
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