【作者】 夏鑫；

【导师】 魏取福；

【作者基本信息】 江南大学 ， 纺织工程， 2013， 博士

【摘要】 二氧化锡是一种对环境友好、宽禁带(3.6eV)的N型半导体氧化物材料,近些年来,对其进行形貌、结构的改性备受关注,因其改性后的材料拥有独特的光学,电学以及化学性能被广泛应用于各个领域。本课题利用静电纺丝技术协同高温煅烧或碳化处理,制备了实心、空心以及皮芯结构的二氧化锡纳米纤维,并将其应用于光催化降解染料基材、气敏元件以及锂离子负极材料中,重点研究了不同结构二氧化锡纳米纤维的成型机理,以及结构对其性能的影响机制。通过二氧化锡水溶胶,以提拉-浸渍的方法涂覆于高强涤纶纤维并进行光催化降解亚甲基蓝染料实验。其中,使用空气等离子体对纤维进行亲水性预处理,利用力-距离曲线分析单根纤维的模量变化,并进行了纤维的形貌观察和力学性能测试。结果表明,等离子处理有效的提高了纤维对二氧化锡溶胶的吸附能力使其光催化效果明显提高。光催化后,纤维形貌能够保持完整；较之催化前,单根纤维模量降低,强度增加,伸长率下降。利用静电纺丝方法制备二氧化锡／聚醋酸乙烯酯杂化纳米纤维,并应用于光催化降解亚甲基蓝染料。实验证明：纤维的光催化效率随着二氧化锡含量的增加而增加；光催化后,纤维形貌保持完好,纤维模量降低,强力增强。同时,使用二氧化钛掺杂能够有效提高该纤维的光催化性能。分别选择聚醋酸乙烯酯和聚乙烯吡咯烷酮为高分子中间体,五水四氯化锡为二氧化锡前驱体,使用静电纺丝及煅烧处理制备网状及纤维状二氧化锡纳米纤维,并应用于光催化降解染料及锂离子电池负极材料中。通过透射电镜、热重分析、红外光谱分析等手段追踪纤维结构变化。实验证明,网络状二氧化锡纳米纤维在锂离子电池测试中有利于保持电极材料的完整性而具有较好的循环性能；纤维状二氧化锡纳米纤维能够最大程度的吸附并降解染料,在光催化降解染料中表现出优异的性能。同时,使用二氧化硅颗粒掺杂及蚀刻技术成功制备了高比表面积的二氧化锡纳米纤维。依据柯肯达尔效应理论,制备了中空结构二氧化锡纳米纤维及二氧化钛/二氧化锡皮芯结构纳米纤维,详细分析了不同结构的成型机理。利用中空结构二氧化锡纳米纤维的结构优势,在气敏测试中表现出了对乙酰乙酯直线型的响应值以及对乙醇在低浓度下灵敏的响应,特别是该材料对气体测试后的响应恢复时间迅速。将二氧化钛/二氧化锡皮芯结构纳米纤维应用于锂离子电池负极材料时,表现出比中空二氧化锡纳米纤维更稳定的循环性能。利用同轴静电纺丝技术,分别从静电纺丝参数、芯层活性物质含量以及结构构建角度分析了提高锡基纳米纤维作为锂离子负极材料性能的改进方法。同时,使用不同种高分子中间体,即聚丙烯腈,聚乙烯毗咯烷酮,聚甲基丙烯酸甲酯,制备锡基皮芯结构纳米纤维,深入探讨了高分子中间体对其形貌及电化学性能的影响。更多还原

【Abstract】 Tin dioxide is an environmentally-friendly N-type, broad band gap (3.6eV) oxide semiconductor. Nowadays, morphology and structure modification of nano-tin dioxide has attracted much attention because they enable the utilization of the unique optical, electronic, and chemical properties of tin dioxide in different applications.In this research, one-step method for the fabrication of tin dioxide solid, hollow and core-shell nanofibers by directly annealing electrospun composite nanofibers were proposed. And their applications in photocatalysis, gas sensor and lithium ion battery were also tested. It is focus on the forming mechanisms of different structures of tin dioxide nanofibers, and the effect of different morphologies on their applications.Tin dioxide hydrosol was deposited on high tenacity polyester fibers by dip-coating method. The photocatalytic properties of samples were analyzed through the degradation of methylene blue. Atmospheric plasma treatment was used as pre-treatment to improve its hydrophilism. The modulus of monofilament was tested using the force-distence curves, the morphologies and mechanical properties of samples were observed as well. The study revealed that the photocatalytic activity of tin dioxide coated high tenacity polyester fibers were enhanced due to the wettability of high tenacity polyester surfaces improved by plasma treatment. After photocatalysis, the morphologies can be hold as pretreated ones; the modulus of monofilament was decrease, strength was increased as well as elongation was decreased.Tin dioxide/polymer vinyl acetate hybrid nanofibers were fabricated by electrospinning, and the photocatalytic properties of samples were analyzed through the degradation of methylene blue. It is revealed that the photocatalytic activity of tin dioxide/polymer vinyl acetate nanofibers were improved by adding more content of tin dioxide. After photocatalysis, the sample was still retained fibrous structure, but the modulus of single nanofiber was decreased while the strength was increased.At the same time, the photocatalytic property was also improved by adding titanium dioxide doping.Two types of tin dioxide nanofibers, one was cobweb-like structure and the other was fibrous structure were prepared by electrospinning and calcination of polyvinyl acetate/stannic chloride pentahydrate and polyvingl pyrrolidone/stannic chloride pentahydrate precursors, respectively. They were applied in the photocatalytic degradation and the lithium-ion battery tests. The transformation process of nanofibers’structure was tracked by transmission electron microscope, thermogravimetric analysis, Fourier transform infrared spectroscopy and others tests. Experiments have shown that the cobweb-like structure of tin dioxide nanofibers showed better cycling performance in lithium-ion battery tests because it had better ability to preserve the integrity of the electrode structure. On the other hand, the fibrous structure of tin dioxide nanofibers exhibited better photocatalytic activity because they provided higher surface area for absorbing and degrading dye. Additionally, high specific surface areas of tin dioxide nanofibers were obtained by adding silicon dioxide doping and then etched it. According to Kirkendall effect, hollow tin dioxide nanofibers and core/shell tin dioxide/titanium dioxide nanofibers were prepared. The forming mechanisms of those nanofibers were analyzed in details. The hollow tin dioxide nanofibers exhibited an excellect gas sensitivity to ethyl acetate.It also has a high response to a low concentration of ethanol. Especially, the speed of response was fast to all of test-gases. For the core/shell tin dioxide/titanium dioxide nanofibers, they have better cycle performance than hollow tin dioxide nanofibers during lithium-ion battery test.In order to improve tin’s cycle performance in the lithium-ion battery test, core/shell tin/carbon nanofibers were prepared by coaxial electrospinning and carbonization. The elelctrospinning parameters, the ratio of active materials and the structure design were adjusted to get better electrochemical properties. Meanwhile, when the different intermediate polymers, i.e. polyvingl pyrrolidone and polymethyl methacrylate used in the core electrospinning solution, the nanofibers were showed different electrochemical properties during lithium-ion battery test. So the relationship among intermediate polymers and the morphologies of nanofibers and the electrochemical properties were discussed in details as well.更多还原