【作者】 庄建东；

【导师】 刘平； 戴文新；

【作者基本信息】 福州大学 ， 无机化学， 2010， 博士

【摘要】 高压输电线路绝缘子的污秽闪络问题一直是困扰输变电安全的世纪难题。目前防污闪的措施都不能有效防止污秽的积聚，无法从根本上杜绝线路绝缘子的污秽闪络。半导体光催化技术被认为是一种解决环境污染问题的“绿色”技术，而TiO₂因其诸多优点一直处于光催化研究，特别是实际应用研究中的核心地位。我们试图利用TiO₂薄膜的光自洁性能及其电学特性，并结合对薄膜的结构调控研究，提升高压绝缘子的防污闪性能。本论文研究TiO₂膜的构效关系并拓展其应用至输变电领域，对于光催化技术的发展具有理论和实际的双重意义。本论文制备了TiO₂防污闪绝缘子，系统研究了光自洁绝缘子的防污闪作用机理；根据TiO₂薄膜存在的不足，提出调控缺陷以改进薄膜光催化性能的思路，并对缺陷位的作用机理进行较为系统的研究。具体研究内容包括：（1）采用喷涂法将TiO₂溶胶涂覆于陶瓷绝缘子表面，制备光自洁绝型缘子，考察光自洁绝缘子的物化性能和光自清洁能力，并对其电气性能进行比较测试；（2）利用有限元方法模拟仿真绝缘子电场分布，探讨TiO₂半导体膜的存在对绝缘子的电气性能的影响机理；（3）在应用研究的基础上，提出在TiO₂双层膜中引入缺陷进行改性的思路，表征了TiO₂薄膜中缺陷的化学状态，考察了缺陷的存在方式及其位置对薄膜光催化性能的影响，建立了缺陷影响电荷转移的作用模型。研究结果表明，（1）利用旋转喷涂法可在绝缘子表面制备均匀的TiO₂薄膜，该薄膜具有良好的光催化性能及活性稳定性。通过各项积污试验表明，相对于普通绝缘子，制得的光自洁绝缘子具有较好的光自清洁能力；（2）只要处理得当，亲水性TiO₂半导体膜的存在，并不会降低绝缘子电气性能，相反，在湿污条件下，绝缘子的闪络电压还得到一定提高，提高幅值约为6%¹2%；（3）有限元电场仿真分析表明，TiO₂膜的存在能够改善绝缘子的电场分布，有效抑制局部放电的发生与发展，从而提高光自洁绝缘子的闪络电压；（4）合理结合溶胶镀膜技术与冷等离子体处理技术，可得到带有缺陷的TiO₂双层薄膜，且缺陷可存在于膜层的界面上形成“界面缺陷”；（5）缺陷能够捕获电子，提高TiO₂薄膜光生载流子的分离效率，从而提高薄膜的光致亲水性能及其对RhB染料的光催化氧化能力，而缺陷的位置对RhB染料分子在TiO₂膜上的吸附和降解行为产生极大影响；（6）“界面缺陷”具有与“表面缺陷”类似的促进光催化作用，同时还表现出更高的稳定性，有极大的实际应用价值。论文的创新点：（1）首次将TiO₂光催化薄膜应用于高电压输电线路绝缘子的防污闪，不仅为绝缘子防污闪提供了新的思路，同时拓展了光催化技术的应用领域；（2）首次制得含有“界面缺陷”的TiO₂膜，提升了薄膜的光催化活性和光致亲水性，还增强了缺陷的稳定性。同时提出了“界面缺陷”对光生载流子以及光催化性能的具体影响机理。本结果为TiO₂光催化剂的性能改进提供普适性的理论依据和实现途径。更多还原

【Abstract】 The insulators for outdoor high-voltage insulation usually suffer from thepollution flashover, imperiling the reliability of the high voltage power system. Thoughvarious measures have been carried out, the pollution flashover is still unable to beprevented fundamentally because of the irresistible accumulation of contaminations onthe surface of insulators. Photocatalysis is a “green” technology for the environmentalremediation issues with solar energy. Titanium dioxide （TiO₂）, is considered to be oneof the ideal photochemical materials due to its merits, has become the most extensivelystudied photocatalyst in the researches, especially in the application researches ofphotocatalysis. We seek to use the self-cleaning and electrical properties of TiO₂function film for promoting the anti-contamination performance of highvoltageinsulators. In addition, modification research is also carried out to further upgrade thephotocatalytic performance of TiO₂film by modulating the characters of TiO₂structure.It is of great significance to ascertain the structure-activity relationship of the TiO₂filmand broaden its application fields, in both theoretical and practical aspects.In this thesis, the TiO₂coated porcelain insulators were prepared successfully, andthe function mechanism of the TiO₂film in promoting the anti-contaminationperformance was investigated systematically. According to the weakness of TiO₂filmin the practical application, a new method of controlling the location of defect sites wasused to improve the photocatalytic performance of TiO₂film. Furthermore, the actionmechanism of these defect sites in photocatalysis was also studied in detail. Theseworks are as follows:（1） The TiO₂sol was coated on the porcelain insulators byspraying method to prepare the photoinduced self-cleaning insulators. Thephysicochemical properties, self-cleaning and electric performances of the as-preparedporcelain insulators have been tested comparetively.（2） Using ANSYS forfinite-element method （FEM） analysis, the electric field distribution of insulator wassimulated by static electric FEM. Based on the study above, the influence mechanismof TiO₂semiconductor film on the electric performance of porcelain insulators was proposed.（3） A distinct modification method by introducing defects into the TiO₂multilayer was presented to improve the photocatalytic performance of TiO₂film. Thechemical states of these defects were characterized in detail. Furthermore, theinfluences of defect sites on the photocatalytic performances were studied, and aninteractive activation model was also proposed to clear the role of defects in theelectron transfer process.The research work obtained some new results and insights as follow:（1） Anuniform and compact TiO₂film can be prepared on the porcelain insulators byspin-spraying method. Compared with the uncoated insulators, the TiO₂coatedinsulators exhibits a stronger self-cleaning ability in the heavy pollution environmentdue to the excellent photocatalytic performance of TiO₂films.（2） In our study, theelectric performances of TiO₂coated insulators do not decline for the existence of TiO₂film, which is of semi-conductivity and hydrophilicity. Instead, even higherperformances are observed in the tests of wetting flashover and artificial contaminationflashover. The growths in the flashover voltages of insulators are determined to be6%¹2%.（3） Based on the electric field simulation results, the TiO₂film can amelioratethe distribution of electric field along the insulator, subsequently suppress theoccurrence and development of the partial discharge, and promote the flashover voltageof the insulators finally.（4） Defective TiO₂films are successfully prepared by acombination of cold plasma treatment and sol-gel dip-coating technology. Moreover,the defects can exist between two TiO₂layers to form the TiO₂film with “interfacedefects”.（5） These defects, no matter whether they are located at the surface or at theinterface, can improve the photoactivity of the TiO₂film. The defects are considered toact as functional electron traps to reduce the recombination of electrons and holes,resulting in the promoted photocatalytic properties of TiO₂films. However, the locationof defects played an important role in the adsorption and photodegradation behaviors ofthe RhB dye molecules.（6） Moreover, the interface defects are proved to be morestable than the surface defects, indicating that this modification method is value inpractical application.The innovations of this thesis are as follows:（1） The TiO₂photocatalytic film isfirstly applied for preventing the high voltage porcelain insulators from pollutionflashover. The study not only provides a new way to deal with the pollution flashoveraccident of insulators, but also broadens the application fields of photocatalysistechnology.（2） The “interface defects” are propounded and successfully prepared forthe first time. Interface defects, which are more stable than the surface defects, can also affect the photoinduced electron-hole recombination process, and promote thephotoactivity and photoinduced hydrophilicity of TiO₂film. Furthermore, the influenceof defects’ location on the photocatalytic reaction behaviors has been discussed in detail.The effect mechanisms of defects on the photocatalysis are also proposed. This studywould be of great benefit to offer a general theoretical guide and a realization way forimproving TiO₂photocatalytic performances.更多还原