TiO_2纳米管阵列生长进程及微观结构的研究

Formation Process and Microstructure of TiO_2 Nanotube Arrays Prepared by Anodization

采用高纯度的Ti箔作为阳极，以Pt片为阴极，在0．1％～1．0％HF水溶液中，电压0．4～14．5V，温度5-40℃范围内进行恒压阳极氧化制备TiO2膜。使用电化学工作站测试了线性扫描阳极极化曲线及阳极氧化过程中的电流密度-时间曲线：并使用扫描电子显微镜对氧化膜的平衡形貌进行观察；研究了阳极氧化时间、电压、电解液浓度以及温度对平衡生长氧化膜结构的影响。结果表明：阳极氧化工艺参数对氧化膜的形成速度、纳米孔孔径、纳米管阵列长度有显著影响。增大电解液浓度以及升高电解液温度，均有利于加快形成结构稳定的氧化膜，表现在到达氧化膜稳定生长的时间缩短，且平衡时纳米管的平均长度缩短。随电压增大，氧化膜生长加速，但获得平衡生长的时间相对延长；纳米孔孔径及纳米管的长度都随之增大。

In order to control the morphologies of TiO2 nanotube arrays, it is significant to ＂investigate the effects of anodization parameters on the formation process and the microstructure of nanotube arrays. Titanium （99.6%） was anodized in 0.1 - 1.0 wt% HF solutions by using Pt as cathode in this work. Anodization process was carried out at voltage range from 0.4 V to 14.5 V and solution temperature from 5 ℃ to 40 ℃. The linear sweep anodic polarization curve and current density-time curves were obtained by means of electrochemical workstation. The morphology of the oxide films was observed with SEM. The effects of time, anodizing voltage, solution temperature on the formation process and the microstructure of titania arrays were studied, respectively. The results show that the growth rate, the nano-pore diameter and the thickness of titania film are obviously affected by anodic oxidation condition, which increased with increasing voltage. But the higher, the voltage, the longer, the time, to achieve balanced growth. It is also found that a higher solution temperature or a higher HF concentration is beneficial to improve the growth rate, shorten the time to equilibrium and reduce the steady nanotube length at equilibrium stage.