氧化钛纳米管阵列制备及形成机理

Electrochemical Fabrication and Formation Mechanism of TiO_2 Nanotube Arrays on Metallic Titanium Surface

采用电化学阳极氧化法在HF水溶液体系使纯钛表面形成一层结构规整有序的高密度TiO2纳米管阵列,考察了几种主要的实验参数(阳极氧化电压、温度、时间、电解液浓度)对TiO2纳米管阵列形貌和尺寸的影响.结果表明,阳极氧化电压是影响氧化钛形貌和纳米管尺寸的最主要因素,而温度和电解液浓度只影响TiO2纳米管阵列形成的时间.对TiO2纳米管阵列进行X射线衍射(XRD)和扫描电子显微镜(SEM)的分析,初步表征了TiO2纳米管阵列的电学性质.并讨论了TiO2纳米管的形成机理.

High density, well ordered and uniform titanium oxide nanotube arrays were fabricated by electrochemical anodic oxidation on a pure titanium sheet. A number of synthesis parameters for the preparation of titanium oxide nanotube arrays in hydrofluoric-acid have been investigated. The results show that voltage is the most important fator to control the appearance and sizes of TiO2 nanotube arrays. The average tubes diameter increases with increasing anodizing voltage. XRD and SEM techniques have been used to characterize the TiO2 nanotubes. It is showed that the TiO2 structure depends on the heating condition, amorphous phase is found at room temperature, the anatase phase is the predominant phase at 450 degreesC, and further heating to 600 degreesC the rutile phase of TiO2 appears in the XRD pattern. The SEM shows that average diameter of the TiO2 nanotubes is about 80 similar to 90 nm at 20 V anodizing voltage. A possible growth mechanism for the nanotubes formation has been proposed. Moreover, the I-V of TiO2/Ti interface has been characterized. It is demonstrated that the intense rectifying characterization of TiO2/Ti interface is attributed to the presence of a thick barrier layer between TiO2 nanotubes and the Ti substrate.