【作者】 张炜；

【导师】 刘兴军；

【作者基本信息】 厦门大学 ， 材料物理与化学， 2007， 硕士

【摘要】 TiO₂是一种重要的宽禁带半导体材料,主要有3种晶型,即金红石、锐钛矿和板钛矿结构,其中金红石和锐钛矿属四方晶系,板钛矿属正交晶系。自从1972年发现TiO₂电极在光照下可以分解水以来,TiO₂以其光催化性和光致亲水性在有机污染物光降解和自清洁方面得到广泛的研究和应用。TiO₂薄膜光催化剂具有易回收、无毒、低成本、高效、杀菌、除臭及抗腐蚀等特点,使之在空气净化、污水处理、自洁和防雾等方面有着广阔的应用前景。本论文将纳米TiO₂与铝板联系起来,在铝板表面制备了纳米TiO₂薄膜,在不损失铝板原有性能的基础上,得到了兼有光催化和自清洁功能的金属铝复合材料。由于传统的方法多涉及高温转晶过程,需要经过400℃以上的高温热处理。而高温热处理工业化成本高,同时也限制了基板的选择。考虑到铝板的耐热性,作者深入研究了铝板表面低温制备TiO₂的薄膜技术,对TiO₂在污水处理和空气净化领域的实用化具有重要的现实意义。本文着重发展了TiO₂薄膜的低温制备技术,分别采用溶胶-凝胶法,过氧钛酸法和热液法三种方法在铝板表面低温制备了纳米TiO₂薄膜,分别采用SEM、UV-Vis、XRD、XPS、FT-IR、Raman等手段对薄膜样品进行表征,并测试了这三种不同方法制备TiO₂薄膜的光催化活性和光致亲水性,为实现铝基板表面制备TiO₂薄膜工业化提供理论基础。主要研究内容及成果如下:1.溶胶-凝胶法直接制备的TiO₂薄膜是无定形的,通过对不同基底的薄膜样品在450℃条件下退火处理后得到了锐钛矿型TiO₂薄膜。研究发现不同基底光催化活性存在很大的差异,通过XPS深度分析薄膜中各元素的原子状态及其分布,得到不同基底界面扩散规律,指出界面扩散直接导致薄膜光催化活性的差异,并从结晶理论和电子迁移角度解释了这一现象。基板随着层数的增加,光催化效率有所增加,6层膜以后亚甲基蓝的光降解率就基本不发生变化,达到了一个最佳厚度。2.采用过氧钛酸法和热液法,通过优化工艺参数,分别在温度低于100℃的条件下分别制得了具有锐钛矿晶型的TiO₂水溶胶,在铝板上拉膜直接得到锐钛矿型TiO₂薄膜,本论文系统研究了薄膜表面形貌及结构和不同层数TiO₂薄膜的光降解亚甲基蓝溶液的性质,结果表明4层膜以后亚甲基蓝的光降解率就基本不发生变化,达到了一个最佳厚度。同时也分别考察了两种方法制备的TiO₂薄膜的光致亲水性。3.以上三种方法相比较,可以得出,溶胶-凝胶法由于界面扩散的存在具有很强的牢固性,所制备的TiO₂薄膜具有较好的光催化活性和光致亲水性。缺点是需要400℃以上的高温处理薄膜才具有光催化活性,成本较高;过氧钛酸法工艺复杂,消耗大量的水,所制备的TiO₂薄膜牢固性一般,光催化活性和光致亲水性也一般,优点是不需要额外的热处理;热液法所制备的TiO₂薄膜牢固性最差,光催化活性和光致亲水性也最差,优点是工艺简单,不需要额外的热处理。更多还原

【Abstract】 TiO₂ is a very important wide bandgap semiconductor, which mainly include three crystal structures. Anatase and rutile are tetragonal. Brookite is orthorhombic. From 1972 years, the first water splitting was reported using a TiO₂ photoanode, TiO₂ with photocatalysis and photoinduce hydrophilic properties has attracted much attention in terms of organic contaminants and self-cleaning applications. The TiO₂ films with many interesting properties, such as easy to reuse, non-toxicity, low cost, excellent efficiency, sterilization, deodorization, anti-corruption, which have a wide applied field of air cleaning, waste water purification, self-cleaning and anti-fogging.TiO₂ nano-crystalline and Al substrate are combined together by author, and the TiO₂ thin films on Al substrate were prepared in the condition of no changing the properties of Al, which has obtained photocatalytic and self-cleaning cermet composite materials. However, most traditional method require processing temperatures higher than 400℃for the crystallization of TiO₂ particles, which is high cost and have a limit the use of other substrates. As Al substrate is easy to melt, it is significant to the fields of waste water purification and air cleaning that lucubrate TiO₂ thin films on Al substrate at lower temperatures.The main goal and motivation of the present work focused on the preparation of TiO₂ thin films on Al substrate at low temperatures. Nanocrystalline TiO₂ thin films were deposited on Al substrates at low temperatures by Sol–gel method, peroxo-titanic acid method and hydrothermal method, respectively. The synthesized thin films were characterized by canning electron microscopy （SEM）, UV-Visible Spectrophotometer （UV-Vis）, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, FT-IR Spectroscopy （FT-IR） and Raman spectroscopy （Raman）. Photocatalytic and hydrophilic properties of TiO₂ thin films fabricated by the those methods were investigated each other, which provide a theory base of industrialization for depositing TiO₂ thin films on Al substrates. The main results and progresses of this thesis are outlined as following:1. TiO₂ thin films prepared directly by Sol-gel method were amorphism; Anatase-type TiO₂ took place at calcination temperature 450℃. It was found that different substrates showed some difference of photocatalytic activities. Elements of different depths in the thin films were measured by XPS, which received the law of interface diffusion of different substrates. The interface diffusion between TiO₂ and substrates led to the difference of photocatalytic activities and the results was explained by the theory of crystal and electron transfer. In addition, as the number of layers increased the photocatalytic efficiency improving. Photocatalytic efficiency attained to maximum when the number of layers more than 6 layers.2. The anatase-type TiO₂ Sol was synthesized less than 100℃by peroxo-titanic acid method and hydrothermal method, respectively. Low-temperature dipping coating of anatase films on Al substrate and the morphologies and structure for the TiO₂ films were investigated. The photodegradation activity of methylene blue （MB） solutions under UV irradiation was studied. Photocatalytic efficiency attained to maximum when the number of layers more than 4 layers and the photoinduced hydrophilic properties were also investigated.3. The three methods were compared each others. TiO₂ films on Al substrate were prepared by Sol-gel method showed good adhesion mainly due to interface diffusion, excellent photocatalytic activities and photoinduced hydrophilic properties. But the disadvantage was heat treatment above 400℃, which led to high cost; TiO₂ films on Al substrate were synthesized by peroxo-titanic acid method show little adhesion, some photocatalytic activities and photoinduced hydrophilic properties, in addition, the process was complicated and wasted of abundant water; TiO₂ films on Al substrate were prepared by hydrothermal method showed least adhesion, least photocatalytic activities and photoinduced hydrophilic properties. But hydrothermal method is simple, no heat treatment was required to obtain nano-sized crystals of TiO₂更多还原