Creation of super high performance photocatalyst by control of nanomicrostructure of titanium oxide

以四异丙醇钛（TTIP）为原料，采用溶胶-凝胶法制备了不同种类的TiO_2。我们成功地以1，3-丁二醇为原料合成了高结晶度的前驱体Ti（OCH（CH_3）CH_2CH_2O）_2，以乙二醇为原料合成了高结晶度的前驱体Ti（OCH_2CH_2O）_2。其中，1，3-丁二醇烷氧基二醇钛在346 ℃时发生了剧烈的分解，转化为具有方棒骨架的TiO_2相。前驱体在空气中500 ℃煅烧，可容易地合成出长1.5 μ m、宽0.3 μ m的四方棒状TiO_2。四方棒状TiO_2的骨架是由直径为25 nm的细小TiO_2颗粒构成的。EXAFS和XPS分析揭示了5-配位的存在。在光催化氧化乙醛的反应中，获得了与P25相当的光催化活性。这种活性是由于TiO_2颗粒中氧缺陷的高度分布，它们是构成方棒骨架的组成部分。此外，氧缺陷有效地作为光氧化位点通过捕获由UV照射产生的空穴。结果表明，氧缺陷和方棒状结构是光氧化活性产生的必要条件

Various TiO_2 were prepared by sol-gel process using titanium tetraisopropoxide (TTIP) and different dilos. We prepared successfully the highly ctystalline precursors, Ti (OCH (CH_3)CH_2CH_2O)_2 from 1, 3-butanediol and Ti (OCH_2CH_20)_2 from ethylene glycol. In particular, the titanium alkoxy-diolate from 1, 3-butanediol was drastically decomposed at 346℃ and transformed to TiO_2 phase with the square rod framework. The square rod TiO_2, whose typical size was estimated to be 1.5μm long and 0.3μm in width, was easily synthesized by the calcination of precursors at 500℃ in air. The framework of square rod TiO_2 was constructed from fine TiO_2 particles with 25 nm in diameter. EXAFS and XPS analyses revealed the presence of 5-coodinated. Ti species and oxygen defects.The photocatalytic activities as high as P25 was achieved during the photo-oxidation of acetaldehyde. The activity was due to the high distribution of oxygen defects of TiO_2 particles, which were components of the construction of the square rod framework. In addition, the oxygen defect acted effectively as a photo-oxidation site by the capture of hole generated by UV irradiation. It concluded that both oxygen defect and square rod shape were essential for the generation of the photo-oxidation activity