【作者】 马保宏；

【导师】 王成伟；

【作者基本信息】 西北师范大学 ， 凝聚态物理， 2008， 硕士

【摘要】 二氧化钛具有独特的湿敏、气敏、紫外光吸收、光电转化及光催化性能,在传感器、介电材料、自清洁材料、有机-无机太阳能电池、光催化降解污染物等领域有着广阔的应用前景。TiO₂纳米管因其特殊的结构而表现出更优异的性能。本论文以“阳极氧化法制备高度有序TiO₂纳米管（多孔）阵列膜的研究”为题,主要述及以下几方面的研究工作:1.分别在HF水溶液、含NH4F和H2O的乙二醇有机溶液中对Ti箔进行阳极氧化,得到高度有序、分布均匀、垂直取向的TiO₂纳米管阵列结构。通过阳极氧化工艺条件（如阳极氧化电压、电解液的选择与配比以及氧化时间等）实现了对其结构参数（如管径、管壁厚度、管密度、管长等）的有效控制。利用XRD研究了纳米管阵列的物相结构。结果表明:通过电解液的选配和退火条件的优化可控制TiO₂纳米管阵列的物相组成及其晶化程度。2.在SiO₂玻璃衬底上用脉冲激光沉积（PLD）技术,分别沉积Ti和Ti/Al膜,经电化学阳极氧化成功制备了多孔TiO₂/SiO₂和TiO₂/Al/SiO₂纳米复合结构。实验研究了Al过渡层对多孔TiO₂薄膜光吸收特性的影响。发现,无Al过渡层的多孔TiO₂薄膜其紫外吸收峰在270nm处,且峰强不随阳极氧化工艺参数调节;而有Al过渡层的多孔TiO₂薄膜其紫外吸收峰红移至293nm处,峰强和峰形不仅受阳极氧化电压调节而且受Al过渡层厚度的影响也很敏感。进一步分析了多孔TiO₂薄膜吸收边附近的光跃迁特性。3.通过分析阳极氧化过程中的电流-时间曲线,研究了TiO₂纳米管阵列膜和多孔TiO₂薄膜的生长机理。认为两种结构的形成过程均发生了场致氧化、场致溶解和化学溶解等三个反应。对于前者,TiO₂纳米管阵列的形成是这三个反应共同作用并逐步达到动态平衡的结果,其形成须经历致密氧化层的形成、多孔层的形成和纳米管的形成及稳定生长三个阶段的演化过程;对于后者,多孔TiO₂薄膜的形成是这三个反应未能达到动态平衡的结果。更多还原

【Abstract】 TiO₂ nanomaterials have widely studied due to their unique electrical and electrochemical properties that are suitable for sensing, catalysis and solar cells. In recent years, TiO₂ nanotubes with high surface-to-volume ratios have received considerable attention because of their potential applications of highly efficient photocatalysis and photovoltaic cells. This dissertation titled“Investigation of The TiO₂ nanotube arrays and porous TiO₂ films prepared by anodic oxidation”mainly describes the following work and results:1. The highly ordered and uniform TiO₂ nanotube arrays are fabricated by anodic oxidation of titanium foil in HF aqueous solution or ethylene glycol containing NH4F and deionized water. The diameter, density, length and wall thickness of nanotube arrays can be controlled effectively by varying anodization parameters including electrolyte composition, voltage, and time. The microstructures of the titania nanotube arrays are characterized by X-ray diffraction （XRD）. The results show that the structure and crystallinity of titania nanotube arrays can be controlled by varying electrolyte composition and annealing condition.2. The porous TiO₂/SiO₂ and TiO₂/Al/SiO₂ nanostructures are fabricated by anodic oxidation of titanium or titanium/aluminum thin films deposited on transparent SiO₂ glass substrates with pulsed laser deposition （PLD） technique. The influence of Al buffer layer on the optical absorption of the porous TiO₂ thin films is investigated. The results show that without Al buffer layer the UV absorption peak of the porous TiO₂ films is fixed at 270 nm and the intensity of absorption peak is not modulated via anodic potential. However, with Al buffer layer the UV absorption peak will shift to 293 nm, and the intensity of absorption peak is not only modulated via anodic potential, but also sensitively influenced by the thickness of Al buffer layer. Moreover, the optical transition property of porous TiO₂ thin films at absorption edge is analyzed.3. The growth mechanism of TiO₂ nanotube arrays and porous TiO₂ thin films is studied by analyzing current-time curves recorded during anodization. The results show that the field assisted oxidation of Ti metal to form titanium dioxide, field assisted dissolution of Ti metal ions in the electrolyte and chemical dissolution of Ti and TiO₂ are three key processes for formation of TiO₂ nanotube arrays and porous TiO₂ thin films. When three processes occurred simultaneously and reached dynamic balance, the TiO₂ nanotube arrays formed, otherwise, the porous TiO₂ thin films formed.更多还原