锰氧化物纳米材料的可控合成与表征

发布时间：2018-05-31 16:33

本文选题：锰氧化合物 + 纳米材料　；参考：《延边大学》2015年硕士论文

【摘要】：锰氧化物作为一种重要的过渡金属氧化物,由于其独特的物理化学性质,在催化、电池、磁性和吸附等技术领域具有极其重要的研究意义和应用价值.相比其体材料,锰氧化物纳米材料显现出更为优异的性能,成为近年来材料研究领域的热点.锰氧化物纳米材料的性能与其形貌、尺寸和晶体结构紧密相关.因此,实现锰氧化物纳米材料的可控制备,设计和制备出各种形貌、尺寸和结构的锰氧化物纳米材料成为合成领域的一个重要研究课题.以高锰酸钾与乙二醇为原料,利用水热法成功制备出γ-MnOOH纳米棒,系统地研究了水热反应条件(反应时间、反应温度)对最终产物形貌、尺寸及晶体结构的影响,并对γ-MnOOH纳米棒的形成机制进行了分析.研究发现在水热体系中,γ-MnOOH纳米棒的形成经历了片状生长、自组装与溶解再结晶三个阶段,随后在不同温度与气体氛围中对γ-MnOOH纳米棒煅烧获得MnO2纳米棒、Mn2O3纳米棒和Mn3O4纳米棒.研究结果表明γ-MnOOH是制备锰氧化物的理想前驱物.以KMnO4与NaHSO3为原料,利用水热法实现了α-MnO2纳米棒与γ-MnOOH纳米棒的可控转变.研究了水热反应条件(反应物浓度比、反应温度)对最终产物形貌、尺寸及晶体结构的影响.在反应体系中,通过调节反应物NaHSO3的浓度实现了α-MnO2纳米棒与γ-MnOOH纳米棒的水热可控转变.研究发现反应温度对α-MnO2纳米棒的形貌有重要的影响,随着反应温度的升高,产物的形貌经历颗粒状—纤维状—棒状的变化.振动样品磁强计(VSM)测量表明α-MnO2纳米棒在室温下表现顺磁性.利用简单、高产的低温沉淀合成方法成功地制备出了各种晶体结构与形貌的锰氧化物纳米材料,系统地研究了反应温度、反应时间、H2O2含量、反应物浓度、碱的含量及不同碱源对锰氧化物纳米材料形成的影响,研究发现通过调节H2O2含量或各种反应物浓度比实现了γ-MnOOH纳米棒、δ-MnO2纳米片、α-Mn2O3纳米立方块和Mn3O4纳米颗粒的可控制备.根据透射电子显微镜(TEM)的分析,我们提出了束状γ-MnOOH纳米棒的形成经历了片层生长、溶解再结晶和定向吸附三个阶段.此外,在不同条件下对γ-MnOOH纳米棒进行煅烧获得了束状MnO2,Mn2O3,和Mn3O4纳米棒.
[Abstract]:Manganese oxide, as an important transition metal oxide, has great significance and application value in the fields of catalysis, battery, magnetism and adsorption due to its unique physical and chemical properties. Compared with the bulk materials, manganese oxide nanomaterials show more excellent properties and become a hot spot in the field of material research in recent years. The properties of manganese oxide nanomaterials are closely related to their morphology, size and crystal structure. Therefore, the controllable preparation of manganese oxide nanomaterials, the design and preparation of various morphologies, sizes and structures of manganese oxide nanomaterials have become an important research topic in the field of synthesis. 纬 -MnOOH nanorods were prepared by hydrothermal method using potassium permanganate and ethylene glycol as raw materials. The effects of hydrothermal reaction conditions (reaction time, reaction temperature) on the morphology, size and crystal structure of the final product were systematically studied. The formation mechanism of 纬-MnOOH nanorods was analyzed. It was found that the formation of 纬 -MnOOH nanorods in hydrothermal system underwent three stages: flake growth, self-assembly and dissolution and recrystallization, and then calcined 纬 -MnOOH nanorods at different temperatures and gas atmospheres to obtain MnO2 nanorods and Mn3O4 nanorods. The results show that 纬 -MnOOH is an ideal precursor for the preparation of manganese oxide. The controllable transition between 伪 -MnO2 nanorods and 纬 -MnOOH nanorods was realized by hydrothermal method using KMnO4 and NaHSO3 as raw materials. The effects of hydrothermal reaction conditions (reactant concentration ratio, reaction temperature) on the morphology, size and crystal structure of the final product were studied. In the reaction system, the hydrothermal transition between 伪 -MnO2 nanorods and 纬 -MnOOH nanorods was achieved by adjusting the concentration of the reactant NaHSO3. It was found that the reaction temperature had an important effect on the morphology of 伪 -MnO2 nanorods. With the increase of reaction temperature, the morphology of the products changed from granular to fibrous. Vibratory sample magnetometer (VSM) measurements show that 伪 -MnO2 nanorods exhibit paramagnetism at room temperature. Manganese oxide nanomaterials with various crystal structures and morphologies were successfully prepared by a simple and high-yielding low-temperature precipitation synthesis method. The reaction temperature, reaction time and concentration of H _ 2O _ 2 were systematically studied. The effects of alkali content and different alkali sources on the formation of manganese oxide nanomaterials were investigated. It was found that the controllable preparation of 纬 -MnOOH nanorods, 未 -MnO2 nanomaterials, 伪 -Mn2O3 cubic blocks and Mn3O4 nanoparticles could be achieved by adjusting the H2O2 content or the reactant concentration ratio. According to the analysis of TEM, we propose that the formation of bunchy 纬 -MnOOH nanorods goes through three stages: lamellar growth, dissolved recrystallization and directional adsorption. In addition, the 纬 -MnOOH nanorods were calcined under different conditions to obtain the bunched MNO _ 2o _ 2 mn _ 2O _ 3 and Mn3O4 nanorods.
【学位授予单位】：延边大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O614.711

【参考文献】