基于二氧化锰纳米片构建的功能性纳米材料与性能研究

发布时间：2018-05-28 07:58

本文选题：二氧化锰纳米片 + 有机无机杂化　；参考：《广东工业大学》2015年博士论文

【摘要】：纳米片是一种新型的二维纳米材料。大多无机层状化合物可通过剥离获得分散的单层纳米片。剥离得到的单层纳米片常常呈现正电性或者负电性,可以作为组装新型纳米材料的基本单元。在本研究论文中,以二氧化锰纳米片为基本构建单元,通过不同的合成技术,控制合成以二氧化锰纳米片为基本单元组成的各种结构锰氧化物材料,并且结构各异的氧化锰材料在能源(二甲醚催化燃烧)、环境保护(废水处理)以及能源储存设备等方面表现出很好的应用前景。本论文主要研究内容及结果有以下几个方面：1、采用插层组装法制备了大层间距的有机无机杂化层状氧化锰材料。两步插层法主要包括,将超声剥离得到的层状氧化锰纳米片与CTAB(十六烷基三甲基溴化铵)进行静电组装,得到有机分子插层结构的烷基铵阳离子-二氧化锰(CTAB-MO);随后通过离子交换方式,将羟基铝阳离子引入到层状氧化锰的层间,得到有机-无机复合改性层状氧化锰材料CTAB-Al-MO。利用X射线衍射(XRD)、热重-差热分析(TG-DTA)、透射电镜(TEM)和傅立叶红外光谱(FTIR)等技术,研究合成产物的层间结构特性。结果表明,所合成产物具有大层间距(1.59 nm)和大比表面积(161 m2/g)；热稳定性较高,在空气中300℃焙烧2 h后,仍然保持良好的层状结构。我们还发现,CTAB的加载量决定着复合产物CTAB-Al-MO中的铝含量。当复合材料应用到污水处理中时,发现复合材料对甲基橙模拟染料具有较高的去除率。5min时,脱色率达到95%。研究结果对进一步了解有机-无机复合改性层状二氧化锰的结构及其应用具有很重要的意义。研究结果发表在Journal of Solid State Chemistry (2013,198,371-378)上。2、采用剥离组装法和原位氧化还原技术制备了金属氧化物(氧化铝)层柱氧化锰多孔材料,并将其应用于新型清洁能源二甲醚的催化燃烧反应。本研究的效果是将具有良好稳定性的氧化铝作为柱撑剂,通过化学方法对层状氧化锰进行插层组装,得到高热稳定性(≥500℃)的氧化铝柱层状氧化锰多孔材料。层柱氧化锰多孔材料在空气中400℃焙烧3h后仍保持良好的层状结构,层间距为0.67nm。当将层柱氧化锰多孔材料应用于二甲醚催化燃烧反应时,发现其具有更高的低温催化燃烧活性和稳定性。起燃温度T10%降至140℃,完全转化温度T90%为149℃；在170℃下,200h内保持二甲醚转化率90%。O2-TPD, XPS等分析结果表明,层柱氧化锰催化剂具有丰富的氧物种,其中低温和中温活性氧物种在二甲醚催化燃烧反应中起了至关重要的作用；与此同时,氧化铝柱撑剂能够促进这些氧物种的迁移。瞬态响应技术结果证明,氧化锰催化剂表面晶格氧(Mn=O)在二甲醚的催化燃烧反应中被消耗,继而由气相氧再生补充。研究结果发表在Microporous and Mesoporous Materials (2013,181,105-110)上。3、二氧化锰的传统合成技术常常通过二价锰离子与高锰酸根的氧化还原反应。本研究中,二氧化锰纳米片直接作为反应材料,取代了传统法中的高锰酸盐或锰盐,通过水热技术合成特殊枝状结构的氧化锰材料。多枝状的β-MnO2的制备主要通过两个步骤,包括用二氧化锰纳米片辅助水热在160℃下24小时合成多枝状γ-MnOOH前躯体和在空气中经400℃煅烧处理所获得的γ-MnOOH前躯体。煅烧后得到的枝状β-MnO2具有特殊的端部结构,即具有凹陷的开放端和锥形的封闭端。组装和脱落机制的提出解释了特殊枝状结构的形成。此外,合成时通过控制反应体系的pH值或者加入一定量的表面活性剂SDBS作为反应物,可生成一维棒状和枝状产物,从而实现y-MnOOH枝状结构和一维棒状结构的选择性生长。研究成果发表在Materials Letters (2012,79288-291)上。4、在NaOH-乙二醇回流体系,以PVP为表面活性剂,H2O2为氧化剂,简单快捷(1h)地合成由厚度约为10nm的二维纳米片组装成的氧化锰纳米花球,花球直径为300-500 nm。系统地研究了各种合成因素,如反应物的用量和反应时间等对产物的影响；发现OH'/Mn2+的摩尔比在形成高结晶度的有序的3D二氧化锰纳米结构起了至关重要的作用。结构表征表明,所合成的二氧化锰纳米结构呈现出良好的介孔结构,孔径约为20nm。由于纳米花的纳米尺寸效应和独特的开放式结构,使其具有优越的吸附性能、电化学性能。吸附时间为10min时,Birnessite型Mn02对丽春红的脱色率达到了95%,达到快速脱色的效果。扫描速率为2mVs-1,样品Birnessite型Mn02比电容计算值为191F/g。虽然Mn02花形微球的合成已有报道,但寻求经济、简单易行、环境友好的可控合成路径仍然具有非常重要的研究意义。据我们所知,在本研究中首次报道采用多元醇回流法制备3D二氧化锰纳米结构。研究成果发表在Industrial and Engneering Chemistry Research (2013,52,9586-9593)上。5、采用了二氧化锰纳米片辅助水热法和原位聚合法构建单分散的二氧化锰／聚苯胺同轴纳米线(MNW/PANI),取代了传统水热法中的二价锰离子和高锰酸盐氧化还原合成法。所合成的高度交织纳米网状结构的二氧化锰／聚苯胺同轴构象为高性能电容器的组装提供了良好的电极材料。MNW/PANI (14h)在扫描速率2 mV s-1下比电容值高达485 mF/cm2,远远超过了二氧化锰纳米线的比电容(263 mF/cm2)和聚苯胺粉体的比电容(39.75 mF/cm2)。此外,研究中以聚乙烯醇/磷酸(PVA/H3PO4)为固态电解质,采用一种简易方法成功设计组装了以二氧化锰/聚苯胺(MNW/PANI)为电极料的超级电容器。本章所组装的电容器的漏电流值非常小,稳定值为20.1μA。并且表现出优异的低自放电特性,经过25小时自放电后达到一个稳定的输出电压值0.42 V。与大多柔性电容器相比,本研究合成的固态电容器具有优良的电化学性能,低自放电特性以及高稳定性。
[Abstract]:Nanoscale is a new type of two-dimensional nanomaterial. Most inorganic layered compounds can be stripped to obtain dispersed monolayer nanoscale. The stripped single layer nanoscale is usually positive or negative. It can be used as the basic unit for the assembly of new nanomaterials. In this study, the basic construction of MnO2 nanoscale All kinds of manganese oxide materials composed of manganese dioxide nanoscale are controlled by different synthetic techniques, and manganese oxide materials with different structures have shown good application prospects in energy (two methyl ether catalytic combustion), environmental protection (wastewater treatment) and energy storage equipment. The contents and results are as follows: 1, organic-inorganic hybrid layered manganese oxide materials with large layer spacing are prepared by intercalation assembly method. The two step intercalation method mainly includes the electrostatic assembly of layered manganese oxide nanoscale and CTAB (sixteen alkyl three methyl bromide) by ultrasonic stripping, and the organic molecular intercalation structure is obtained. The alkyl ammonium cation manganese dioxide (CTAB-MO) was introduced into the layer of layered manganese oxide by ion exchange, and the organic-inorganic composite modified manganese oxide material CTAB-Al-MO. was obtained by X ray diffraction (XRD), thermogravimetric differential thermal analysis (TG-DTA), transmission electron microscopy (TEM) and Fu Liye infrared spectroscopy (FTIR). The results show that the synthesized products have large layer spacing (1.59 nm) and large specific surface area (161 m2/g), and the thermal stability is high. After roasting at 300 C for 2 h in the air, the synthesized products still maintain a good layered structure. We also found that the amount of CTAB loading determines the content of aluminum in the compound product CTAB-Al-MO. When the composite material is applied to sewage treatment, it is found that when the composite material has a high removal rate of.5min, the decolorization rate of 95%. is of great significance to the further understanding of the structure and application of organic-inorganic composite modified layered manganese dioxide. The results are published in Journal of Solid State Chemi Stry (2013198371-378).2, the porous metal oxide (alumina) layer manganese oxide porous material was prepared by the stripping assembly method and in situ oxidation reduction technology, and applied to the catalytic combustion reaction of the new clean energy two methyl ether. The effect of this study is to use the alumina with good stability as a pillared agent and through chemical method. The layered manganese oxide porous material with high thermal stability (> 500 C) was obtained by intercalation. The layer column manganese oxide porous material remained well layered after 3H calcined at 400 C in air, and the layer spacing was 0.67nm. when the porous material of manganese oxide was applied to the catalytic combustion reaction of two methyl ether. It has higher catalytic activity and stability at a higher low temperature. The ignition temperature T10% is reduced to 140 degrees C, and the complete conversion temperature is T90% 149. At 170, the conversion rate of two methyl ether in 200H is 90%.O2-TPD, XPS and other analysis results show that the layer column manganese oxide catalyst has a rich oxygen species, of which the low temperature and medium temperature active oxygen species are stimulated by two methyl ether. At the same time, the alumina pillared agent can promote the migration of these oxygen species. The transient response technique results show that the surface lattice oxygen (Mn=O) of the manganese oxide catalyst is consumed in the catalytic combustion reaction of two methyl ether and then supplemented by gas phase oxygen regeneration. The result of the study is published in Microporous and Mesoporous Materials (2013181105-110).3, the traditional synthesis technology of manganese dioxide is often redox reaction by two valence manganese ions and permanganate. In this study, manganese dioxide nanoscale was directly used as a reaction material to replace permanganate or manganese salt in traditional method, and the oxidation of special branched structure was synthesized by hydrothermal technology. Manganese material. The preparation of the multi branched beta -MnO2 is mainly through two steps, including the synthesis of a multi branched gamma -MnOOH precursor and the gamma -MnOOH precursor obtained by calcining at 400 C in the air for 24 hours at 160 degrees centigrade with manganese dioxide nanoscale. After calcining, the dendritic beta -MnO2 has a special end structure, that is, it has a depression. The opening and conical closed ends. The assembly and shedding mechanism explains the formation of a special branch structure. In addition, one dimensional rod like and branched products can be generated by controlling the pH value of the reaction system or adding a certain amount of surface active agent SDBS as reactant, from which the y-MnOOH branch structure and the one dimensional bar like structure are realized. The research results were published on Materials Letters (201279288-291).4, in NaOH- glycol reflux system, PVP as surface active agent, H2O2 as oxidant, and simple and fast (1H) to synthesize manganese nanomaterials composed of two dimensional nanometers with thickness about 10nm, and the diameter of the flower ball was 300-500 nm. systematically studied. The effects of synthetic factors, such as the amount of the reactant and the reaction time, have been found, and the mole ratio of OH'/Mn2+ has been found to play a vital role in the formation of an ordered 3D manganese dioxide nanostructure with high crystallinity. The structural characterization shows that the synthesized manganese dioxide nanostructure presents a good mesoporous structure with a pore size of about 20nm. due to the nano structure. The nano size effect and unique open structure of the flower made it have superior adsorption and electrochemical properties. When the adsorption time was 10min, the decolorization rate of Birnessite Mn02 to the red spring red reached 95%, reaching a rapid decolorization effect. The scanning rate was 2mVs-1 and the Birnessite Mn02 specific capacitance of the sample was 191F/g. although Mn02 flower. The synthesis of microspheres has been reported, but it is still of great importance to seek economic, simple and environmentally friendly controllable synthetic paths. According to our knowledge, the preparation of 3D manganese dioxide nanostructures by polyol reflux method is reported for the first time in this study. The research results are published in Industrial and Engneering Chemistry Research (2013,529586-9593) upper.5, a monodisperse manganese dioxide / polyaniline coaxial nanowire (MNW/PANI) was constructed by using manganese dioxide nanoscale assisted hydrothermal method and in situ polymerization to replace the two valent manganese ion and permanganate redox synthesis in the traditional hydrothermal method. The coaxial conformation of polyaniline provides a good electrode material for the assembly of high performance capacitors, which provides a good electrode material.MNW/PANI (14h) with a specific capacitance of 485 mF/cm2 at a scanning rate of 2 mV s-1, far exceeding the specific capacitance (263 mF/cm2) and polyaniline powder (39.75 mF/cm2) of the manganese dioxide nanowires. In addition, the study is made of polyvinyl alcohol / phosphoric acid (PVA/). H3PO4) for solid-state electrolytes, a simple method is used to successfully design and assemble a supercapacitor with manganese dioxide / polyaniline (MNW/PANI) as the electrode. The leakage current of the capacitor assembled in this chapter is very small, the stable value is 20.1 u A. and shows excellent low self discharge characteristics. After 25 hours self discharge, it reaches a steady state. Compared with most flexible capacitors, the output voltage value of 0.42 V. has excellent electrochemical performance, low self discharge characteristics and high stability.
【学位授予单位】：广东工业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB383.1;O614.711

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