【作者】 陈芃；

【导师】 谭欣；

【作者基本信息】 天津大学 ， 环境科学， 2012， 博士

【摘要】 TiO₂材料由于具备高催化活性、无毒性和化学稳定性等优点而被广泛应用于资源与环境领域，TiO₂薄膜因比粉体易于从反应体系中分离与回收利用而备受关注。本文将一种新型物理沉积技术，即对向靶磁控溅射法应用于TiO₂薄膜制备过程，可有效避免溅射粒子对沉积薄膜的轰击作用，提高靶材的利用率，所制备薄膜与基底结合牢固。以两个对向平行放置的钛靶为溅射靶材，分别选取Ar与O₂为工作气体和反应气体，采用直流反应溅射法在FTO导电玻璃基底上制备了TiO₂纳米薄膜。通过FE-SEM和AFM对不同溅射时间段的TiO₂纳米薄膜进行表面形貌分析，结果显示TiO₂纳米薄膜在基底上呈先层状后岛状（Stranski-Krastanow）的生长模式。通过台阶仪、XRD、FE-SEM、HR-TEM、AFM和UV-Vis等表征手段，详细分析了对向靶磁控溅射过程各个条件参数对所制备TiO₂纳米薄膜晶体结构、表面形貌与光学性质的影响。溅射功率主要影响TiO₂纳米薄膜的沉积速率，薄膜厚度与溅射功率呈线性增加的关系；当溅射功率大于280W时薄膜开始由非晶状态转化为锐钛矿结构，但结晶度较低。退火处理可使TiO₂纳米薄膜获得足够自由能，促进TiO₂颗粒的表面迁移与相互团聚，并提高薄膜的结晶度。Ar/O₂流量比是影响靶面上溅射过程与氧化过程速率的决定性因素，当Ar/O₂流量比低于1:1时溅射过程进入靶面氧化模式，薄膜沉积速率和结晶度均有所降低；当Ar/O₂流量高于1:1时，随着溅射室内氧气流量的增加，薄膜由纯锐钛矿结构转变为锐钛矿-金红石混晶结构。高溅射气压会抑制金红石的生长，当溅射气压小于2.5Pa时，沉积在基底上的TiO₂纳米薄膜结晶度随溅射气压的升高而提高；若溅射气压继续增大则会导致沉积薄膜的结晶度下降。以异丙醇（iso-propanol，简称IPA）气体为目标降解物检测所制备薄膜的光催化活性；以TiO₂纳米薄膜电极的瞬态光电流检测薄膜的光电性能，研究确定具备最优光催化活性和光电性能的TiO₂纳米薄膜制备条件为：溅射功率350W，溅射气压2.5Pa，Ar/O₂流量比1:1，后期退火温度550℃。该薄膜可在120min紫外照射时间内降解初始浓度为90ppm的IPA气体，且在IPA降解实验中呈现出良好的催化活性稳定性。在光催化反应中异丙醇首先转化成丙酮再被氧化为CO₂，中间伴随有少量乙醛出现。在外加电压0.6V条件下，该薄膜在标准三电极体系中的瞬态光电流密度可达1.02mA/cm2，具有较优光电转换性能。更多还原

【Abstract】 TiO₂have been widely used in many environmental applications due to its highphotocatalytic activity, non-toxicity and chemical stability. Compared to powders,TiO₂thin films could be easily separated from the reaction system and thus attracted agreat deal of attention. Here we proposed a new physical deposition technique,namely DC facing target magnetron sputtering for TiO₂thin film preparation with theaim of prevention of high energetic ions bombardment and increase of targetutilization during the sputtering process. The prepared films coule be stably coated onvarious kinds of substrates with strong adhesion.TiO₂thin film was deposited on FTO substrates using a pair of facing Ti targetsas sputtering targets. Pure Ar gas and O₂gas were selected as the working gas andreactive gas respectively. A series of TiO₂thin films deposited under differentsputtering times were characterized by Field Emission Scanning Electron Microscopy（FE-SEM） and Atomic Forece Microscope （AFM）, which proved TiO₂thin filmsforming in Stranski-Krastanow growth on FTO substrates.The effects of sputtering parameters on the crystal structure, surface morphologyand opitical property of TiO₂thin films were investigated by the characterizationincluding surface roughness tester, X-Ray diffraction, FE-SEM, AFM and UV-VisibleSpectrophotometer （UV-Vis）. Firstly, sputtering power mainly affected the depositionrate of TiO₂thin film and the film thickness increased linearly with the sputteringpower. The amorphous films transform to anatase with the higher sputtering powerthan280W. Sencondly, annealing treatment could improve the crystallinity of TiO₂thin films by providing free energy which promoted the surface migration andreunification of grains. Thirdly, Ar/O₂flow ratio played an important role in thesputtering and oxidation reaction on the target surface. Both of deposition rates andcrystallinity of TiO₂thin films reduced with lower Ar/O₂flow ratio than1:1due to“the oxidation mode”. When Ar/O₂flow ratio was higher than1:1, the phase of TiO₂thin films change from pure anatase into mixed-phase as the O₂flow increased.Fourthly, high pressure inhibited the growth of rutile phase. When the sputteringpressure was lower than2.5Pa, the crystallinity of deposited films increased with theincreasing sputtering pressure. However, the followed increasing pressure caused anapparently derease of the crystallinity of deposited films.The photocatalytic activities of TiO₂thin films were evaluated by thedecomposition of gaseous iso-propanol （IPA） under UV light irradiation. And the photoelectric performances of the deposited films were analyzed by measuringtransient photocurrent of TiO₂electrodes. The optimized sputtering parameters suchas350W,550centigrade,1:1and2.5Pa were determined by the above measurments.Under UV irradiation, IPA degradation rate of the optimized TiO₂thin film whichkept high stability constant during the repetitive experiments, could reach to100%in120min with the IPA inicial concentration of90ppm. Simultaneously, the highesttransient photocurrent with the value of1.02mA/cm2was obtained by the samesample.更多还原