锐钛矿型二氧化钛（001）表面光催化的研究

发布时间：2018-06-04 17:57

本文选题：程序升温脱附 + 锐钛矿型TiO_2　；参考：《中国科学技术大学》2017年硕士论文

【摘要】：二氧化钛(TiO2)的光催化特性近年来备受关注,但目前的研究多集中在TiO2的金红石相,尤其是(110)表面,而对于理论活性更高的锐钛矿型TiO2(001)表面则鲜有报道。本文采用自行搭建的基于高灵敏度质谱仪的程序升温脱附谱(temperature programmed desorption, TPD),利用脉冲激光沉积(pulsed laser deposition, PLD)手段制备出高质量的锐钛矿型TiO2(001)单晶薄膜,研究了甲醛,甲醇等小分子在锐钛矿型TiO2(001)表面的热分解以及光催化分解行为。第1章概述了 TPD的基本原理,研究方法以及能得到的表面基本信息如脱附活化能等。介绍了本文所用的质谱基本构造以及根据不同实验要求对仪器加装的一些改进。并对二氧化钛光催化机理及相关研究进展进行了简要概括,如Ti02基本结构,光生载流子迁移过程等。最后描述了本文的样品制备方法。第2章主要描述甲醛(CH2O)在锐钛矿型TiO2(001)的还原表面的热分解和光催化分解行为。实验发现,甲醛在该表面化学脱附峰值温度在200K,无光照时在缺陷位热反应生成乙烯(C2H4),脱附温度为560 K。经过紫外光照后,甲醛一方面光致脱附,另一方面被光催化生成C2H4,甲酸(HCOOH)和甲醇(CH3OH)等。HCOOH在高温分解产生一氧化碳(CO)于550K脱附。我们认为,在光照过程中甲醛的C-H键被活化,生成中间产物HCO-以及H增原子,进而生成C2H4,HCOOH 和 CH30H。第3章主要围绕室温(或260 K)下甲醇在锐钛矿型Ti02(001)的新制备表面(as-grown)的耦合反应。实验表明,在室温下向as-grown表面通入大量甲醇时,甲醇能在该表面发生耦合反应生成多碳产物,并在340K脱附。通过脱附信号中的m/z=27和39的信号可以断定产物中存在碳碳键。该温度脱附的多碳产物成分比较复杂,至少包含4种,已经确定了其中两种分子式为C3H802和C4H10O。该反应受样品厚度,表面缺陷浓度以及(1 X4)重构影响。
[Abstract]:The photocatalytic properties of TIO _ 2 / TIO _ 2 have attracted much attention in recent years, but most of the current studies are focused on the rutile phase of TiO2, especially on the surface of TiO110. however, there are few reports on the surface of anatase type TIO _ 2O _ (001) with higher theoretical activity. In this paper, a high quality anatase TIO _ 2O _ 2O _ (001) single crystal thin film was prepared by using a self-built temperature programmed desorption spectrum based on a high sensitivity mass spectrometer and pulsed laser deposition, PLD) method. Thermal decomposition and photocatalytic decomposition of methanol and other small molecules on anatase TIO _ 2 / O _ (001) surface. In chapter 1, the basic principle, research methods and surface activation energy of TPD are summarized. The basic structure of mass spectrum used in this paper and some improvements to the installation of the instrument according to different experimental requirements are introduced. The photocatalytic mechanism of TIO _ 2 and its related research progress are briefly summarized, such as the basic structure of Ti02, photogenerated carrier transport process and so on. Finally, the method of sample preparation is described. Chapter 2 describes the thermal decomposition and photocatalytic decomposition of formaldehyde (Ch _ 2O) on anatase TIO _ 2o _ (001) reduction surface. It was found that the peak temperature of chemical desorption of formaldehyde on the surface was 200K, and the thermal reaction of ethylene C2H4 was formed at the defect site without illumination, and the desorption temperature was 560K. After UV irradiation, formaldehyde was photodesorbed on the one hand, on the other hand, it was photocatalyzed to form C _ 2H _ 4, formic acid HCOOH) and methanol Ch _ 3OH). HCOOH decomposed at high temperature to produce carbon monoxide (CO) desorption at 550 K. It is considered that the C-H bond of formaldehyde is activated during illumination to form the intermediate product HCO- and the H atom, and then to form C _ 2H _ 4O _ (HCOOH) and Ch _ (30H). In chapter 3, the coupling reaction of methanol at room temperature (or 260K) on the newly prepared surface of anatase Ti02C001 is studied. The experimental results show that when a large amount of methanol is injected into the surface of as-grown at room temperature, the coupling reaction of methanol can take place on the surface to produce multi-carbon products and desorption at 340 K. The m/z=27 and 39 signals in the desorption signal can be used to determine the carbon bond in the product. The multi-carbon products desorbed at this temperature are complex and contain at least 4 kinds, two of which have been identified as C3H802 and C4H10O. The reaction was influenced by the thickness of the sample, the concentration of surface defect and the reconstruction of the sample.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O614.411;O643.36

【相似文献】