Preparation And Characterization Of Manganese Oxide Thin Film

Manganese dioxide is a kind of important industrial uses of oxide. It can be used in industry for super capacitor electrode material, dry battery as a depolarizing agent, glass manufacturing of decoloring agent, chemical industry as the oxidant, the catalyst in organic synthesis, paint and ink drying agent and molecular sieve and other areas. In the field of preparation of manganese dioxide film, according to the chemical and physical properties of material and product synthesis material, preparation methods can be divided into three categories:liquid phase method, gas phase method and solid phase method. Anodic oxidation method and sol-gel method widely used at present are the drawbacks of high cost and difficult to mass production. Therefore it takes the method of the chemical precipitation growth method to prepared MnO2thin films, which has the advantages of simple operation, low cost. In the mixed solution at a certain temperature, with Mn2+as the reducing agent, BrO3-as an oxidant, MnO2thin films are prepared by precipitation growth on nickel foam sheet.Experiments on the MnO2thin films prepared by chemical precipitation growth process, find the influence of temperature, reaction time, reactant concentration, pH value and other factors on preparing. Then the XRD and SEM techniques are used to characterize the microstructure of MnO2films, and it studies its effects as electrode material by cyclic voltammetry, AC impedance, constant current charge/discharge of electrochemical testing technique.Process of MnO2thin films prepared by chemical precipitation growth method is affected by temperature, when the temperature is below45℃, MnO2deposition on the nickel foam substrate ratio is very low, it is difficult to form a MnO2thin film; while the temperature is higher than65℃,the oxidation speed become faster to change the crystal type of MnO2and generate larger particles of MnO2precipitation, the specific resistance is greatly increased, is not conducive to the modification of the electrode material. When the temperature is in the range of50～55℃, in the SEM characterization of arrangement of MnO2microstructures of crystal shape neat, regular structure, the film is uniform and stable. The concentration of the reactants will also affect the coating effect, through a series of comparative experiments. The optimum initial concentration of reactants:(Mn2+concentration0.02mol/L, BrO3-concentration of0.2mol/L); reaction time under the control of the deposition time of10hours is the best, more than10hours of film layer caused too thick; in addition, the pH value has great influence on the morphology and the electrochemical properties of prepared MnO2thin films, preparation conditions of the best performance in pH is about7, Testing the electrochemical properties of MnO2in0.5mol/L Na2SO4electrolyte on 5mA constant current charging and discharging capacitance, specific capacitance is214.10F/g.