【作者】 顾彦辉；

【导师】 麦立强；

【作者基本信息】 武汉理工大学 ， 光电子及信息材料， 2010， 硕士

【摘要】 钒是一个典型的多价态过渡金属元素,它可形成多种不同类型的钒氧化物。其中一维钒氧化物纳米材料由于其特殊的优异性能,得到了越来越多的发展与应用。本文采用流变相自组装法合成出了两种不同形貌的纳米线,并用LB技术将产物进行有序构筑,又用流变相自组装法一步合成了捆状VO2纳米线阵列。主要内容和结果如下：1.采用流变相自组装法合成了V3O7·H2O纳米线,经400℃的淬火,得到V2O5纳米线,用CTAB对其进行表面处理,并用LB技术将其组装成局部有序的纳米线阵列,用广角XRD、小角XRD、UV-vis、SEM等手段对其结构进行表征,测试其电化学性能,结果表明：经过LB有序组装,纳米线具有了局部有序结构,这种有序排列为Li+离子的扩散提供了更多而有序的途径,改善了放电过程中Li+离子的扩散通道,从而更有利于锂离子的扩散。2.采用流变相自组装法合成了VO2纳米线,对其进行表面处理,并用LB技术将其组装成局部有序的纳米线阵列,用XRD、SEM等手段对其结构进行表征,并研究了其电化学性能,分析循环伏安和电导率测试结果发现VO2纳米线LB膜的电流密度和比容量比镀膜之前的VO2纳米线有了两个数量级的提升,这可能归因于VO2纳米线单层膜的则有取向和局部有序结构。分析了电化学性能的提升与VO2纳米线有序结构的关系,并在此基础上提出了锂离子在有序阵列中的嵌入和脱出机理。3.利用流变相自组装法成功地合成了捆状VO2纳米线阵列,并用XRD、SEM等手段对结果进行了表征。提出并分析了捆状VO2纳米线阵列的形成机理。测试了捆状VO2纳米线的电化学性能,发现高度有序的捆状VO2纳米线阵列的首次充放电容量较高,但是循环稳定性有待提高。并且发现,捆状VO2纳米线阵列结构的有序性和稳定性,对材料的电化学性能有着较大的影响。更多还原

【Abstract】 Vanadium is a typical multi-valence transition metal element, which can form different types of vanadium oxides. Due to its unique and excellent properties, One-dimensional vanadium oxide nano-materials have gained an increasing attention in many areas. In this thesis, by using rheological self-assembled method, we synthesized the nanowires with different morphologies, such as the bundle-like VO2 nanowires arrays. Besides, the LB technique was used to construct the nanowires in order. The content of the article reads as follows:1. V3O7·H2O nanowires were synthesized via a rheological self-assembled method, and by annealing the as-synthesized V3O7·H2O nanowires at 400℃in air, V2O5 nanowires were obtained. Then the peoducts were functionalized with cetyltrimethyl ammoniumbromide. Finally, through LB assembly, locally-ordered nanowire arrays were obtained. The structure of the VO2 nanowire monolayers was characterized via viawide-angle XRD, UV-vis, SEM. Using LB technique, nanowire films were deposited on aluminum foil and used as electrode for lithium ion batteries. Electrochemical properties were analyzed, and the results illustrated that the locally-ordered nanowire film provided a better and more orderly way for Li+ion diffusion.2. VO2 nanowires were synthesized via a rheological self-assembled method, they were functionalized with stearic acid and cetyltrimethyl ammoniumbromide, then locally-ordered nanowire arrays were obtained by LB assembly. The structure of the VO2 nanowire monolayer was characterized by using XRD, SEM and other methods. Besides, we also studied the electrochemical properties. CV investigation confirmed that electrochemical capacity of VO2 nanowires could be enhanced about two orders of magnitudes through LB assembly. I-Ⅴinvestigation showed the conductivity could be improved by about two orders of magnitudes. By analyzing the mechanism of the Li+ion insertion/extraction along VO2 nanowires before and after LB assembly, the improvement of electroactivity of VO2 nanowires may result from the orientated, locally ordered structure and the increased surface areas.3. Bundle-like VO2 nanowire arrays were synthesized via the rheological self-assembled method, The structure of the products were characterized by using XRD, SEM. The formation mechanism of bundle-like VO2 nanowire arrays was proposed, and the electrochemical properties of products were tested. The results show that the charge/discharge capacities of the first cycle are realtivley high, but the cycling ability need to be improved. It is also shown that the electrochemical properties of the bundle-like VO2 nanowire arrays are related to the orderliness and stability of the special structure.更多还原