Aerosol-Assisted CVD of Titanium Dioxide Thin Films from Methanolic Solutions of Titanium Tetraisopropoxide; Substrate and Aerosol-Selective Deposition of Rutile or Anatase
Aerosol-Assisted CVD of Titanium Dioxide Thin Films from Methanolic Solutions of Titanium Tetraisopropoxide; Substrate and Aerosol-Selective Deposition of Rutile or Anatase
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DOI：
10.1002/cvde.201006872
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发表时间：
2011-03-01
影响因子：
--
通讯作者：
Parkin, Ivan P.
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文献类型：
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作者：
Edusi, Cynthia;Hyett, Geoffrey;Parkin, Ivan P.
以异丙醇钛(TTIP)为原料，采用气溶胶辅助化学气相沉积(AA-CVD)法制备了二氧化钛(TiO2)薄膜。沉积是在400-550℃的温度下在玻璃、钢和钛衬底上进行的，薄膜的形貌与典型的气溶胶辅助工艺以及在低压或大气压(AP)CVD中使用的TTIP完全不同。薄膜表现出一些与衬底有关的形貌和性能。尤其是在550℃时，钢表面的薄膜呈现出针状和棒状颗粒。X射线衍射和拉曼光谱分析表明，在钢和钛衬底上只能得到金红石相，而在玻璃上可以得到锐钛矿相、锐钛矿/金红石混合物或金红石相，这取决于衬底温度。在550℃下在所有衬底上形成的二氧化钛薄膜对水滴都是疏水的，接触角在101-110度范围内。这些薄膜在空气中加热到100摄氏度以上时变得亲水，或者在254 nm辐射下照射时变得超亲水，产生小于5度的水接触角。令人惊讶的是，在没有气溶胶的钢衬底上使用APCVD下的TTIP，在400-550摄氏度时只形成锐钛矿型的二氧化钛，而使用甲醇气溶胶输送系统在TTIP上形成金红石。因此，甲醇气溶胶的使用对沉积化学有控制作用。染料墨水测试表明，二氧化钛薄膜是一种活性的光催化剂，并且能够在牺牲体系中光裂解水以放出氧气。
Titanium dioxide (TiO2) thin films are synthesized using aerosol-assisted (AA) CVD of titanium (IV) isopropoxide (TTIP) in methanol. Deposition is carried out on glass, steel, and titanium substrates at 400-550 degrees C. The films produce morphologies that are radically different to those from typical aerosol-assisted processes, and from the use of TTIP in low or atmospheric pressure (AP) CVD. The films show some substrate-dependent morphology and properties. In particular at 550 degrees C the films on steel show needle-and rod-like particles. X-ray diffraction (XRD) and Raman spectroscopy of the TiO2 films show that on steel or titanium substrates only the rutile form can be obtained, whereas on glass either anatase, anatase/rutile mixtures, or rutile can be obtained, depending on substrate temperature. The TiO2 films formed at 550 degrees C on all substrates are hydrophobic to water droplets, with contact angles in the range 101-110 degrees. These films become hydrophilic on heating to above 100 degrees C in air, or superhydrophillic when irradiated under 254nm radiation generating water-contact angles less than 5 degrees. Surprisingly, use of TTIP under APCVD on steel substrates without an aerosol form exclusively the anatase form of TiO2 at 400-550 degrees C, whereas use of a methanolic aerosol delivery system for the TTIP forms rutile. Hence use of the methanol aerosol has a controlling influence on the deposition chemistry. The TiO2 thin films are shown to be active photocatalysts using a dye-ink test, and are also shown to be able to photo-split water in a sacrificial system to evolve oxygen.