The Specific Morphology Of Manganese Oxide Ion Liquid Secondary Conditions Controllable Preparation Of Study

Manganese oxide, as a well-known transition-metal oxide, has attracted increasing interest because of its special physical and chemical properties, which can be used as catalysts, ion exchange sieves, adsorbents and electrode materials in lithium ion secondary battery and supercapacitor. In this thesis,β-MnO2 with hollow polyhedra morphology is prepared by using ionic liquid assisted hydrothermal synthesis, and the effect of the reaction conditions on the structure and morphology of the obtained materials is also investigated. In addition, the cobalt-manganese hybrid oxide material has been preparated and the capacitive performance has been investaged. The structure and capacity performance of the cobalt-manganese hybrid oxide materials at different molar ratios of cobalt to manganese have also researched.This thesis mainly consists of three sections, reviewer, experiments and conclusion. Introduction part (Chapter 1) reviews the structure, classfications, preparation methods and the appplications of manganese oxide.β-MnO2 with hollow polyhedra morphology has been successfully synthesized under acid condition via an ionic liquid-assisted hydrothermal synthetic method in chapter 2. By using Co(OH)2 as the precursor, the cobalt-manganese hybrid oxide material has been synthesized by a hydrothermal treatment method in KMnO4 solution in chapter 3. The research conclution is finally presented in Chapter 4.In chapter 2,β-MnO2 with hollow polyhedra morphology has been successfully synthesized under acidic condition via an ionic liquid-assisted hydrothermal synthetic method by using KMnO4 as manganese source. The optimal reaction condition for preparingβ-MnO2 with hollow polyhedra morphology is as follows:0.63 g of KMnO4,2 ml HCl (37 wt%) and 0.11 g [BPy][BF4] were added to 13 ml distilled water with stirring for about 15 min, then the solution was transferred to an autoclave with a capacity of 23 ml. The autoclave was kept in an oven at 150℃for 36 h, and then cooled to room temperature. The obtained sediments are collected, washed with distilled water to remove residual reactant, and dried at 50℃for 6 h,β-MnO2 with hollow polyhedra was finally obtained. a-MnO2 with nanowire morphology was obtained by hydrothermal treating the mixed solution for 1 h. Prolonging the hydrothermal treatment time to 6 h, the obtained products posses solid particle morphology, and the materials with uniform size and hollow polyhedra morphology can be obtained by prolonging hydrothermal treatment time to 36 h. Continuing prolonging the hydrothermal treatment time to 60 h, the particle morphology changes into microroll from hollow polyhedra one. On the basis of discussing the hydrothermal reaction time, the content of ionis liquid and acid concentration, the formation process ofβ-MnO2 with hollow polyhedra have been discussed.By using Co(OH)2 as the precursor, the cobalt-manganese hybrid layered material is firstly sythesized by hydrothermal treating the suspension of Co(OH)2 and KMnO4 at 180℃for 24 h after ultrasonic treatment, and the cobalt-manganese hybrid oxide material was then obtained when the cobalt-manganese hybrid layered material is calcined at 400℃for 2 h in chapter 3. The specific capacitance of cobalt-manganese hybrid oxide material is 267 F/g at a sanning rate of 5 mV/s in NaSO4 solution (1 mol/L). The structure changes and capacitance of the products obtained at different molar ratios of cobalt to manganese (1:1,1:2,1:3,1:5) are also discussed.