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TiO2纳米管阵列结构.该结构高度有序、分布均匀、垂直取向,且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)可实现对其结构参数(如管径、管壁厚度、管密度、管长等)的有效控制.利用XRD研究了TiO2纳米管阵列的物相结构.结果表明:退火前的TiO2纳米管阵列为无定形结构;分别在真空和氧气氛中500℃退火后,HF水溶液中制备的样品出现单一锐钛矿相,而在含NH4F和H2O的乙二醇有机溶液中氧化得到的样品则出现锐钛矿和金红石的混合相.前者在氧气氛中退火后锐钛矿晶化程度较高;后者在真空中退火后混合相的晶化程度也较高.初步分析了TiO2纳米管阵列的形成机理.这些结果对基于TiO2纳米管阵列的传感器及有机-无机异质结太阳电池的应用研究是非常有益的.
The highly ordered and uniform TiO2 nanotube arrays were fabricated by anodic oxidation of titanium foil in HF aqueous solution or ethylene glycol containing NH4 F and deionized water. The diameter, density, length and wall thickness of nanotube arrays can be controlled effectively by varying the anodization parameters including electrolyte composition, voltage, and time. The microstructures of the titania nanotube arrays were characterized by X-ray diffraction (XRD). The results showed that the asanodized titania nanotubes were amorphous. And when annealed in vacuum or in oxygen ambient at 500%, the samples prepared in HF aqueous solution showed only anatase phase, and the samples prepared in ethylene glycol containing NH4 F and deionized water showed both anatase and rutile phases. And the former and the latter batch of samples became better crystallized when annealed in oxygen and in vacuum, respectively. Furthermore, the controllable growth mechanism of nanotube arrays is discussed.