微含水量电解液中高管径比TiO_2纳米管阵列的制备

Fabrication of TiO_2 Nanotube Arrays with High Length to Diameter Ratio in Electrolyte Containing Trace Amount of Water

通过阳极氧化法在微含水量为0.5wt%的NH4F/乙二醇/H2O酸性电解质体系中制备了管径大、高管径比的二氧化钛（TiO2）纳米管阵列。采用SEM、XRD等测试手段对TiO2纳米管阵列形貌及晶相进行表征,探讨了不同氧化时间、电压对纳米管阵列形貌的影响,微含水量下氧化电压可以适当增加,更容易得到规整的长纳米管阵列;通过测定样品的光电流和紫外-可见光漫反射吸收光谱,研究分析了含水量以及超声工艺对纳米管光吸收及光电流特性,微含水量下得到的纳米管阵列可见光吸收边红移至420nm,对480~700nm可见光有明显的光吸收,光电流显著增大;丙酮作为超声介质可有效去除纳米管阵列表面的集束,能进一步提高纳米管阵列的光电性能。

Titanium dioxide（TiO2） nanotube arrays with large diameter and high length to diameter aspect ratio were fabricated by anodic oxidation of NH4F/glycol/acidic electrolyte system with trace amount of water. The morphology and crystal phase of the TiO2 nanotube arrays were characterized by using SEM, XRD and other testing methods. The oxidation time and applied voltage control the morphology of nanotube arrays. Higher oxidation voltage with trace amount of water in the electrolytes improves the regularity and length of the nanotube arrays. The water content and ultrasonic applied during synthesis affect the nanotubes light absorption and photocurrent characteristics as shown by photocurrent and UV-Vis diffuse reflectance spectroscopy results. The nanotube arrays synthesized with trace amount of water have a broad visible light absorption edge up to 420 nm.They significantly improved visible light absorption and photocurrent in the range of 480 ~700 nm. Acetone as ultrasound medium can effectively remove the clusters on nanotube array surface and further improve the optical properties of nanotube arrays.