Structure Control of TiO_2 Nanotubes Having Mesopores on Their Tube Wall

将纯PVA纳米纤维浸泡在钛醇盐-乙醇溶液中，制得PVA-钛醇盐杂化纳米纤维。我们的方法很有可能得到一种具有皮芯结构的前驱体纳米纤维，其皮层为PVA-钛醇盐杂化，芯层为纯PVA。通过焙烧前驱体纳米纤维，可以很容易地制备出二氧化钛纳米管。通过改变纯PVA纳米纤维的直径可以控制纳米管的直径。本研究所能形成的纳米管的外径范围为300-600 nm，得到的纳米管具有较高的比表面积，氮气吸附等温线表明纳米管壁上存在中孔。在400~600℃范围内形成锐钛矿型二氧化钛，且随着焙烧时间的延长，峰强度增大。在70 0℃以上形成金红石型二氧化钛。通过对亚甲基蓝和乙醛的光催化降解，评价了纳米管的光催化性能。其光催化性能优于市售的锐钛矿型纳米二氧化钛。

PVA-Ti alkoxide hybrid precursor nanofibers were formed by the immersion of pure PVA nanofibers in Ti alkoxide-ethanol solution. It is likely that a precursor nanofiber with a skin-core structure would be obtained by our method ; the skin layer is PVA-Ti alkoxide hybrid, and the core is pure PVA. TiO_2 nanotubes were easily formed by calcination of the precursor nanofibers. The diameter of the nanotube can be controlled by changing the diameter of the pure PVA nanofiber. The range of the outer diameter which can be formed in this study is 300-600nm.The nanotubes obtained had a high specific surface area and the existence of mesopores on the nanotube wall was indicated by the nitrogen adsorption isotherms. Anatase type TiO_2 was formed at 400-600℃, and the peak intensity increases with an increase in the calcination time. Rutile type TiO_2 was formed above 700℃. The photocatalysis of the TiO_2 nanotubes was evaluated using the photocatalytic decomposition of methylene blue and acetaldehyde. There were superior to the photocatalysis of commercially available anatase type TiO_2 nanoparticles.