【作者】 卢晓平；

【导师】 王绪绪；

【作者基本信息】 福州大学 ， 物理化学， 2004， 硕士

【摘要】 二氧化钛光催化剂薄膜的制备是光催化研究中的重要问题之一。现今开发的各种膜化技术，如溶胶－凝胶、悬浮浆料、气相沉积等方法都不同程度地存在缺陷，开发方便、实用和低成本的薄膜制备方法对光催化技术的广泛应用具有重要的实际意义。本论文以溶胶－凝胶法制备的TiO2溶胶为前驱体，采用电泳沉积法在铝合金片基底上制备出了TiO2薄膜，与其它方法相比，电泳法能快速实现TiO2在基底上大量均匀负载。采用乙烯为模型反应物，研究了电泳条件对薄膜光催化性能的影响，并与提拉法制备的TiO2薄膜进行对比；采用SEM、AFM、XRD、DRS等手段评价了TiO2薄膜的表面形貌、尺寸、晶型、吸收带边等物化性能；特别是通过给电泳液中添加助剂制备出了性能优异的光催化薄膜，并通过测定溶胶中TiO2粒子尺寸和迁移率及溶胶的粘度和zeta电势探讨助剂改善膜性能的原因。实验结果表明：（1）在前驱体溶胶温度25℃、两电极直流电压2V和通电3min条件下可实现TiO2膜在铝合金基底上的有效电泳负载，得到薄膜经500℃焙烧1小时（升温速率2℃/min）表现出优良的光催化性能。（2）电泳法制备的TiO2薄膜（简称电泳膜）比提拉法制备的TiO2薄膜（简称提拉膜）对乙烯的光催化氧化转化率在相同反应时间内高近3倍。但由于电泳膜有较高的TiO2沉积量、且结构致密、TiO2的粒径较大，其比活性（单位面积上单位质量TiO2的光催化活性）却比提拉膜的低。（3）添加适量非离子型表面活性剂聚乙二醇（PEG）6000可以有效地改善电泳膜的光催化性能。研究表明随着溶胶中PEG浓度的改变，所制备的电泳膜对乙烯的光催化氧化转化率出现先增大再减小的变化。当给溶胶中添加50 g/L PEG时，可得到高比光催化活性的TiO2薄膜，其对乙烯的光催化活性比未加PEG时得到的电泳膜的活性高8倍多。为理解添加PEG影响电泳膜活性的原因，测定了溶胶的性质。结果表明添加PEG后可降低溶胶的ζ电位，胶粒电迁移率和TiO2胶粒径尺寸，导致溶胶沉积机制的改变，使得膜的致密程度降低，同时PEG高温分解后在膜表面留下空隙，提高了膜的比表面积，从而提高了电泳膜的光催化活性。本论文的主要创新点包括：（1）系统研究TiO2薄膜的电泳沉积条件，并比较了电泳膜与提拉膜的结构和性能差别；（2）首次通过添加PEG利用电泳法制备出了性能优良的TiO2薄膜；（3）从助剂对溶胶电动性质的影响考察并探讨了助剂在TiO2电泳沉积制备中的作用。该研究为制备高活性的实用型TiO2光催化薄膜提供了一种新的方法，为TiO2的产业化研究开辟了一条新途径。更多还原

【Abstract】 The preparation of TiO2 film is one of the most important questions in the field of photocatalysis research. Traditional techniques of preparation of TiO2 film such as dip coating from suspension, sol gel related methods and vapor deposition have a variety of limitations. So the development of convenient, effective and low-cost preparation method has important significance for the extensive application of photocatalysis technology. In this work, TiO2 positive sol particles prepared by a sol-gel technique were immobilized on aluminum alloy plates by electrophoretic deposition (EPD). EPD can give thick and uniform film within a short time compared with other techniques. The effect of electro- phoretic condition for the photocatalytic activity of TiO2 film was evaluated using ethylene as reactant, and the photocatalytic activity of TiO2 film prepared by EPD and dip coating was compared. The physical and chemical properties including the crystal and morphological structure of the film，the size and band-gap-edge of TiO2 particles were characterized by XRD, SEM, AFM, DRS. TiO2 film with high photocatalytic efficiency was obtained by adding an additive to the precursor TiO2 sol. The reason why the addition of the additive to TiO2 sol can improve the photocatalytic activity was discussed by determining the size and mobility of TiO2 particles and the viscosity and zeta potential of sol. The results showed (1) TiO2 film with high photocatalytic activity was immobilized on aluminum alloy plates by EPD on condition that the temperature of TiO2 sol was 25℃，the potential applied for electrophoresis was 2V and lasted for 3min , and the resulting film was calcinated at 500℃ for 1h. (2) the conversion of ethylene over TiO2 film prepared by EPD (called EP-film) was 3 times higher than that over TiO2 film prepared by dip coating (called DC-film). But a more compact film with higher loading and larger size of TiO2 but lower specific photocatalytic efficiency (ethylene conversion over unit mass TiO2 and unit area of TiO2 film) was obtained by EPD compared with dip coating method. (3) the addition of non-ion surfactant polyethylene glycol (PEG) to TiO2 sol could effectively improve the specific photocatalytic activity over the EP-film. The conversion of ethylene of EP-film changed with the change of the concentration of PEG. Optimum specific photocatalytic activity was found in the film prepared by EPD from TiO2 sol <WP=4>containing 50g/L PEG, which was 9 times more than that of the film prepared from sol without PEG. To investigate the effect of the addition of PEG on the property of TiO2 sol, the properties of sol were measured. It was found that the addition of PEG reduced the zeta potential of TiO2 sol, the mobility and size of TiO2 particles, which leaded to the change of mechanism of EPD and lowered the EP-film packing density. And the specific area of the film was enhanced for the decomposition of PEG at high temperature.The innovations of this work include: (1) investigating the conditions of EPD of TiO2 film systemically, and comparing the morphological structure and properties of EP-film with those of DC-film. (2) preparing TiO2 film with high photocatalytic activity by EPD from the TiO2 sol containing PEG for the first time. (3) discussing the effect of PEG in the process of preparation by measuring the electrokinetic properties of TiO2 sol. Here we provide a new method for the preparation of effective TiO2 film with high photocatalytic activity and develop a new approach for the application research of TiO2 technology.更多还原