半导体NiO及其复合氧化物的水热合成及电化学与气敏性能研究

发布时间：2018-05-11 11:06

本文选题：氧化镍 + 纳米结构　；参考：《重庆大学》2015年博士论文

【摘要】：氧化镍是一种重要的p型半导体材料,带隙能量在3.6-4.0 e V之间。氧化镍具备优异的化学和热稳定性,被许多科研工作者所关注,尤其是结构以及功能方面的研究和表征。在众多合成方法中,水热合成法作为一种非常便利,廉价以及用于大规模生产纳米材料的手段可以人为地控制合成多种形貌的纳米氧化镍。由于纳米氧化镍的形貌具有可调性,它已经被广泛地应用于电化学以及气敏等领域。然而,普通的纳米氧化镍形貌所具有的比表面积往往很小,而且本身的导电性很差,这些不良因素限制了它的电化学以及气敏性能。为了改进并提升氧化镍这种半导体材料的性能,设计并且制备拥有超大比表面积的独特纳米结构是非常有必要的。此外,以氧化镍为基础,与其他金属氧化物形成的二元复合氧化物,如钴酸镍、钼酸镍等等,将具有更好的导电性从而可以作为增强电化学以及气敏性能的优选材料。使用了水热法控制合成多种独特纳米结构的氧化镍及其复合物。对于这一系列制备得到的最终产物,诸多先进的电子显微镜被用于表征它们的结构。通过结构表征,具有高品质的产物将被制作成为相应的器件,分别以电极材料和气敏传感器进行电化学以及气敏性能测试。成功合成了低维的氧化镍纳米结构包括一维的纳米线和二维的纳米片。对于氧化镍纳米线,二水草酸镍在此作为其煅烧前的前驱体。在反应的过程中,乙二醇和聚乙二醇这两种表面活性剂的添加与否直接影响到最终这种长且分散的氧化镍纳米线能否成功得到。通过控制水热时氨水的浓度(p H值),成功合成规则且均匀分布的氧化镍六边形纳米片。基于晶体结构和电镜表征,本文对于这种形状规则均一的六边形氧化镍纳米片的生长机理进行了讨论,从理论上阐述了这种结构形成的原因。针对以上两种氧化镍纳米结构,产物分别被加工制作成气敏元件并检测了它们对于乙醇、一氧化碳、甲苯以及氨气等还原性气体的敏感性、稳定性、相应恢复时间和选择性。成功合成了三维氧化镍纳米结构,尤其是纳米花状,通过添加不同的表面活性剂得到多种花状结构。首先采用水热法合成没有任何掺杂的三种氧化镍纳米分层花状结构。适量的聚乙烯吡咯烷酮、丙三醇和溴化十六烷基三甲铵作为表面活性剂可以分别合成由片层自组装而成的山茶花状、玫瑰花状和花球状微结构。根据形核以及晶体生长这两个主要过程,探讨了表面活性剂、反应时间以及反应温度对于最终形貌的影响。此外三种不同花状结构的样品都被制作成气敏元件并用于乙醇气体敏感性的检测。其次,三氧化钨掺杂的氧化镍菊花状纳米结构以及其潜在的气敏性能首次在本文中进行了详细报道。钨掺杂的氧化镍、纯氧化镍以及三氧化钨样品均被制作成气敏元件并用于乙醇气体敏感性的检测,发现这种三氧化钨掺杂的氧化镍菊花状纳米结构表现出最佳的气敏性能。同时,本文亦讨论了三氧化钨的掺杂可以增强气敏性能的机理。通过真空高温煅烧脱脂棉获得碳纤维用作氧化镍纳米片层生长的模板。通过水热法以及不同的热处理方法获得碳纤维氧化镍核壳和氧化镍空心管这两种结构,并将最终产物加工制备成电极测试它们的电化学性能。受益于这种核壳结构,氧化镍片层包裹碳纤维电极材料表现出很高的比电容(1 A g-1电流密度下具有891.1F g-1)、优秀的大电流放电能力(20 A g-1下依然保留83.3%)以及循环稳定性(1000次循环后保持95.43%的比电容)。这使得氧化镍片层包裹碳纤维结构可以作为一种很有应用前景的高性能超级电容器材料。采用两步水热法设计合成钴酸镍以及其硫化产物。产物的结构十分特殊,在微观下可以发现这些立体结构是由片层阵列上自生长纳米针而形成的。自生长的纳米针可以通过控制氟化铵相对剂量的添加而控制其生长。这种硫化后的钴酸镍片状阵列具有良好的导电性,而其表面自生长的纳米针提供了非常可观的比表面积使得该结构拥有优异的电化学性能。以硫化产物做成的电极在15 m A cm-2的电流密度下有着2617.6 F g-1的超高比电容,且在30 m A cm-2的电流密度下依然保持2051.0 F g-1。5000次循环之后仍然保持93.2%的比电容,这种电极表现出的极好循环稳定性使得它成为高性能超级电容器的首选材料。通过一步水热法制备了水槽状钼酸镍空心纳米棒,并进行了一系列物相分析、形貌表征和电化学性能测试。通过测试,这种具有100多长径比的钼酸镍空心纳米棒具有很高的比表面积增加了电极材料在电解液中的接触面积。受益于这种独特结构,钼酸镍空心纳米棒电极材料表现出较高的比电容(1 A g-1电流密度下具有1102.2 F g-1),不错的大电流放电能力(20 A g-1下依然保留64.5%)以及循环稳定性(1000次循环后保持90%的比电容)。这使得水槽状钼酸镍空心纳米棒结构可以作为一种很有应用前景的超级电容器材料。
[Abstract]:Nickel oxide is an important p type semiconductor material with band gap energy between 3.6-4.0 E and V. Nickel oxide has excellent chemical and thermal stability. It has been paid much attention to by many researchers, especially in structure and function. In many synthetic methods, water thermocoagulation is a very convenient, cheap and large amount of use. The means of producing nanomaterials in scale can artificially control the synthesis of nanoscale nanoscale with various morphologies. Due to the tunability of the morphology of nano nickel oxide, it has been widely used in the fields of electrochemistry and gas sensing. However, the surface area of the ordinary nano nickel oxide is often very small and its electrical conductivity is very good. In order to improve and improve the properties of nickel oxide, it is necessary to design and prepare a unique nanostructure with a large specific surface area to improve and improve the properties of the semiconductor material. In addition, the two element compound oxide formed by its metal oxide based on nickel oxide, such as Nickel cobalt, nickel molybdate, and so on, will have better conductivity and can be used as the preferred material for enhanced electrochemical and gas sensing properties. Using hydrothermal method to control the synthesis of various unique nanostructures of nickel oxide and its complex. For this series of final products, many advanced electron microscopes are used to characterize them. The structure characterized by the structure characterization, the products with high quality will be made into corresponding devices, electrochemistry and gas sensitivity tests are carried out with electrode materials and gas sensors. The low dimensional nickel oxide nanostructures, including one-dimensional nanowires and two-dimensional nanometers, are successfully synthesized. The nickel oxide nanowire, two nickel hydrate nickel oxide, is successfully synthesized. In the process of the reaction, the addition of the two surfactants, ethylene glycol and polyethylene glycol, directly affects the success of this long and dispersed nickel oxide nanowire. By controlling the concentration of ammonia (P H) in the hydrothermal process, the regular and uniformly distributed nickel oxide six edges are synthesized. Based on the crystal structure and the electron microscope characterization, the growth mechanism of the hexagonal nickel oxide nanoscale with uniform shape rules was discussed. The reasons for the formation of this structure were discussed in theory. For the two kinds of nickel oxide nanostructures, the products were processed into gas sensitive components and their effects were detected. The sensitivity, stability, recovery time and selectivity of the reductive gases, such as ethanol, carbon monoxide, toluene and ammonia, have been successfully synthesized, and a variety of flower like structures are obtained by adding different surface active agents. The first three kinds of nickel oxide without any doping are synthesized by the addition of different surface active agents. An appropriate amount of polyvinylpyrrolidone, glycerol and sixteen alkyl trimethyl ammonium bromide can be used as surfactants to synthesize camellia flower shape, rose like and flower shaped microstructures, respectively. According to the two main processes of nucleation and crystal growth, the surface active agent and reaction time are discussed. And the effects of the reaction temperature on the final morphology. In addition, the samples of three different flower like structures were made into gas sensors and used for the detection of the sensitivity of ethanol gas. Secondly, the tungsten oxide doped nanostructures and their potential gas sensitivity were first reported in this article. Nickel, pure nickel oxide and tungsten trioxide samples were made into gas sensitive components and used to detect the sensitivity of ethanol gas. It was found that the NiO like nanostructure doped with tungsten oxide showed the best gas sensitivity. At the same time, this paper also discussed the mechanism of the doping of tungsten trioxide to enhance the gas sensitivity. The calcined skimmed cotton obtained carbon fibers used as a template for the growth of nanoscale layer of nickel oxide. By hydrothermal method and different heat treatment methods, the two structures of carbon fiber nickel oxide shell and nickel oxide hollow tube were obtained, and the final products were prepared to form electrodes to test their electrochemical properties. The coated carbon fiber electrode material shows a high specific capacitance (1 A g-1 current density with 891.1F g-1), excellent high current discharge capacity (20 A g-1 still retained under 83.3%) and cyclic stability (95.43% specific capacitance after 1000 cycles). This makes the nickel oxide coating carbon fiber structure as a very useful one before application. The high performance supercapacitor material. The two step hydrothermal method was used to design the synthesized nickel cobalt and its vulcanization product. The structure of the product was very special. At the microcosmic point, these three-dimensional structures were found to be self growing nanowires on the lamellar array. The self growing nanowires can be controlled by the control of the addition of the relative dosage of ammonium fluoride. The vulcanized nickel cobalt sheet array has good electrical conductivity, and the self growing nanowires on the surface provide a very considerable specific surface area that makes the structure excellent electrochemical performance. The electrode made of the vulcanized product has a 2617.6 F g-1 super high specific capacitance at the current density of 15 m A cm-2, and at 30 The current density of M A cm-2 still maintains a specific capacitance of 93.2% after 2051 F g-1.5000 cycles. The excellent cycling stability of this electrode makes it the preferred material for high performance supercapacitors. A single step hydrothermal method is used to prepare the trough like Ni nanorod nanorods, and a series of phase analysis has been carried out. The surface area of the electrode material in the electrolyte is increased by the high specific surface area of the nickel hollow nanorods with a high ratio of 100 length to diameter. The nickel hollow nanorod electrode material shows a higher specific capacitance (1 A g-1 current density). With 1102.2 F g-1), good current discharge capacity (still 64.5% under 20 A g-1) and cyclic stability (90% specific capacitance after 1000 cycles). This makes the trough like nickel hollow nanorod structure as a promising supercapacitor material.

【学位授予单位】：重庆大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ138.13;TB383.1

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