Preparation,Electrochemical And Catalytic Properties Of Manganese Dioxide Nanomaterials

MnO₂ not only possesses the good characteristics of redox but also owns multiple crystalline structures.By changing the preparation conditions,researchers will gain the MnO₂ material with multi-formed and high-proportional surface and multiple active sites,which is widely used in catalysis,supercapacitors,molecular sieves,lithium batteries and other fields.The physical and chemical properties of the MnO₂ limit the application of the material.Whereas these defects can be overcame by compounding with other materials,and its properties can be greatly improved to achieve the synergistic effect of various materials.In this thesis,CS@MnO₂ and Fe₃O₄@MnO₂ composites are prepared and studies its applications in supercapacitors and degraded dyes?1?This thesis with the MnO₂ as its staple and uses Carbon aerogels with a large specific surface area to produce the CS@MnO₂ composites by hydrotherm-al methods and also studies the influence of the change of conditions during the hydrothermal process,such as the influence of the shape and crystal patterns by changing the temperature during reaction.By using 0.5 mol of sodium sulfate as the electrolyte and doing voltammetry and galvanostatic charge/discharge tests in a three-electrode system,researchers will find that the CS@MnO₂ composite material obtained at a hydrothermal condition of 100?is superior in performance and the specific capacitance reaches 178 F/g.The CS@MnO₂ composite material has a large specific surface area at 140?.Using this material for the degradation of methylene blue dyes,and studies the influence of degradation effects by changing the quantity of catalyzer,the p H value and the temperature.The thesis finds that it has a certain effect on the degradation of methylene blue wastewater,and the removal rate can reach 99.3%.?2?This thesis intends to study the size-controllable ring-shaped ferric oxide which is produced by the hydrothermal reaction conditions;and then by treating it in the argon-hydrogen mixed gases we can get the cyclic ferriferrous oxide which then is covered with a layer of amorphous carbon on its different morphologies and finally we can get the Fe₃O₄@MnO₂ composite through hydrothermal reaction.And then we use the Fe₃O₄@MnO₂ composite with magnetism as the catalyzer for the H₂O₂ degradation of the Mythylene Blue to study the effect of degradation by changing the quantity of catalyzer,temperature and the supplementary of ozone.Finally the removal effect of more than 65%can be achieved under the condition of p H>4 when using twice the amount of Fe₃O₄@MnO₂ material.Through the above experimental data and comprehensive analysis,it shows that manganese-based composite materials not only have excellent performance and broad prospects in supercapacitor energy storage,but also its low cost and the reusable characteristics make it own the unlimited prospect in comprehensive degradation of dye wastewater field.