特殊形貌氧化锰材料的控制制备及形成过程研究

发布时间：2018-04-01 00:14

  本文选题：氧化锰　切入点：特殊形貌　出处：《陕西师范大学》2015年硕士论文

【摘要】：氧化锰材料由于价格低廉、环境友好且资源丰富等优点,已经被广泛应用于催化、吸附、传感、离子交换、锂离子二次电池和超级电容器等领域。研究结果表明,材料的晶型、形貌、维数和尺寸等因素影响其光学、电学和磁学性能的发挥。控制制备具有特殊形貌氧化锰材料,进而研究材料的形貌与性能之间的关系具有重要的理论和应用价值。本论文以氧化锰材料为研究主体,通过水热技术控制制备具有特殊形貌氧化锰材料,系统研究反应条件对制备产物晶相和形貌的影响,探讨了不同形貌氧化锰材料的生长过程及电化学性质。全文包括绪论、实验和总结三个部分。第1章绪论部分主要论述了特殊形貌过渡金属氧化物的性质、制备及应用,氧化锰晶体的结构、特殊形貌氧化锰材料的制备、应用及形成机理；实验部分第2章采用水热技术制备了特殊形貌六角星形γ-MnOOH,提出了六角星形γ-MnOOH可能的形成过程；第3章以硫酸锰和过硫酸钾为反应体系,制备了四种不同形貌α-MnO2和特殊形貌(3-MnO2,在探讨材料形成过程的基础上,研究了不同形貌对材料电容性质的影响；第4章为全文总结。在无模板剂或表面活性剂辅助下,以KMnO4为锰源,乙酸乙酯为还原剂和刻蚀剂,200℃水热处理48 h,制备了新颖形貌六角星形γ-MnOOH。通过调节乙酸乙酯的用量、水热反应温度和反应时间等实验参数,得到了六角星形γ-MnOOH 最佳制备条件。应用XRD、FE-SEM、TEM、HRTEM、SAED和原子吸收分析,对制备材料进行了系统表征。在分析实验结果的基础上,提出了六角星形γ-MnOOH的形成过程。结果表明,乙酸乙酯对制备材料的形貌控制起到了非常重要的作用。随着水热时间的延长,乙酸乙酯缓慢分解产生乙酸,乙酸吸附在γ-MnOOH分支纳米棒的侧枝,发生温和的酸刻蚀过程,纳米棒逐渐变细变尖,最终得至γ-MnOOH六角星形形貌。将分支纳米棒和六角星形γ-MnOOH进行煅烧处理,六角星形γ-MnOOH经过拓扑化学转化,形成与前躯体形貌相同的α-MnO2。在无模板剂或表面活性剂辅助下,以硫酸锰和过硫酸钾为研究体系,通过改变体系的温度、浓度和酸度及向体系中添加不同金属离子如铁离子和银离子,分别制备得到了微球状、海胆状、荔枝球状和核-壳结构四种不同形貌α-MnO2,系统研究了阳离子对制备产物晶相和形貌的影响。同时,通过改变反应温度,得到了特殊形貌谷粒状β-MnO2。采用三电极体系,在1 mol L-1 Na2SO4电解液中对制备的四种不同形貌α-MnO2电极材料进行电化学测试。结果表明,四种不同形貌α-MnO2材料中,核-壳结构α-MnO2电极材料具有最好的电容性质,当扫描速度为5mVs-1时,比电容为211 Fg-1。核-壳结构α-MnO2电极材料具有的优良电容性质归于材料特殊的核-壳结构,能够缩短电解质离子嵌入/脱出的路径,提高材料的比电容。
[Abstract]:Manganese oxide has been widely used in the fields of catalysis, adsorption, sensing, ion exchange, lithium ion secondary battery and supercapacitor due to its advantages of low price, friendly environment and abundant resources.The results show that the crystal shape, morphology, dimension and size of the materials affect their optical, electrical and magnetic properties.It is of great theoretical and practical value to control the preparation of manganese oxide materials with special morphology, and to study the relationship between the morphology and properties of the materials.In this thesis, manganese oxide materials with special morphology were prepared by hydrothermal technology. The effects of reaction conditions on the crystal phase and morphology of the products were studied systematically.The growth process and electrochemical properties of manganese oxide materials with different morphologies were investigated.The thesis includes three parts: introduction, experiment and summary.Chapter 1 introduces the properties, preparation and application of transition metal oxides, the structure of manganese oxide crystal, the preparation, application and formation mechanism of manganese oxide materials with special morphology.In the second chapter of the experiment, the hexagonal star 纬 -MnOOH was prepared by hydrothermal technique, and the possible formation process of hexagonal star 纬 -MnOOH was proposed. Chapter 3 was composed of manganese sulfate and potassium persulfate.Four different morphologies of 伪 -MnO2 and special morphologies of 3-MnO _ 2 were prepared. Based on the study of the formation process of the materials, the effects of different morphologies on the capacitive properties of the materials were studied. Chapter 4 is a summary of the full text.A novel hexagonal star 纬 -MnOOH was prepared by hydrothermal treatment at 200 鈩，

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