原位AFM-IR 技术对 TiO2 基光催化降解有机污染物的研究

Characterization of TiO2 photocatalytic degradation of organic pollutants by in-situ AFM-IR

史丽丽

11749115

硕士

物理学

吴文政

2019-05-14

2018-07-11

哈尔滨工业大学

深圳

目前，我国淡水环境受到双酚A(BPA)、苯酚、抗生素等一系列有机污染物的威胁，其中双酚A是一种非常具有代表性的环境内分泌干扰物，降解水源中的BPA是急需解决的问题。为了更好的降解有机污染物，科研工作者在光催化领域做了大量研究，因此了解光催化降解的微观机理对提高光催化效率有重大意义。二氧化钛(TiO2)作为较理想的光催化剂被广泛用于研究，但TiO2由于带隙较宽，可见光利用率很低，导致光催化效率较差。我们通过使用简单的原子层沉积(ALD)方法对TiO2表面进行改性，制备出缺陷态氧化钛薄膜，增加了可见光的吸收。同时，在光催化表面沉积一层Ag纳米粒子，由于表面等离子体效应，Ag纳米粒子具有吸收可见光的能力，能够增加光催化材料的可见光利用率。结合以上两种方法，我们制备出了光催化降解效果较好的复合光催化剂。在制备等离子体光催化复合材料时，Ag纳米粒子呈纳米颗粒状均匀分布在缺陷态氧化钛薄膜材料表面，同时有缺陷态氧化钛暴露出来，对于这种材料在进行光催化降解效果时，不同位置（Ag纳米粒子上、界面处、缺陷态氧化钛薄膜上）的光催化降解效率可能有所不同。因此，我们利用对化学成分具有超高空间分辨率的原子力红外显微镜技术(AFM-IR)及其他表征手段，在不同波长的单色光及模拟太阳光光源的辐照下，原位分析不同位置的光催化降解效果。我们制备出了可以充分利用太阳光的光催化剂，并且发现在波长为365 nm和405 nm的辐照下在Ag纳米粒子处的降解效果略好；在波长为450 nm下在缺陷态氧化钛处的降解效果最佳；在波长550 nm下由于表面等离子体效应，在界面处降解效果最佳；在模拟太阳光光源的辐照下三个不同的位置均发生了降解，是一个比较综合的结果。我们发现，在不同激发波长下，光催化降解效率在不同位置有所不同，产生现象的可能机理也不尽相同。此研究为进一步了解光催化降解有机污染物的微观机理提供了一个参考。

At present, our fresh water environment is threatened by a series of organic pollutants such as bisphenol A (BPA), phenol and antibiotics, among which bisphenol A is a representative environmental endocrine disruptor. Degradation of BPA in water source is an urgent problem. In order to better degrade organic pollutant BPA, researchers have done a lot of research on photocatalytic degradation of BPA. Understanding the microcosmic mechanism of photocatalytic degradation is of great significance to improve the photocatalytic degradation effect.Titanium dioxide (TiO2) is widely used as an ideal photocatalyst for research, but TiO2 has a poor photocatalytic efficiency due to its wide band gap and low visible light utilization rate. By using simple atomic layer deposition (ALD) method to modify the surface of titanium dioxide, defective TiO2 films were prepared, which increased the absorption of visible light. At the same time, a layer of Ag nanoparticles is deposited on the photocatalytic surface, and the visible light utilization rate of the photocatalytic material can be increased by introducing surface plasma effect. The composite photocatalyst with better photocatalytic degradation effect was prepared by combining the above two modifications of TiO2 materials. The introduction of surface plasma effect, Ag nanoparticles in granular evenly distributed on the surface of defective TiO2, at the same time there is defective TiO2 are exposed, for this kind of material in the photocatalytic degradation effect, different positions (Ag nanoparticles/interface between Ag nanoparticles and defective titanium oxide film/defective titanium oxide film) on the photocatalytic degradation efficiency might be different. Therefore, the photocatalytic degradation effect at different positions was studied by in-situ analysis under the irradiation of LED monochromatic light with ultra-high resolution atomic force infrared microscope (AFM-IR) and other characterization methods.We have fabricated photocatalysts that exhibit a better utilization of sunlight. Under illumination of 365 nm and 405 nm, the degradation effect was slightly better at Ag nanoclusters. Under 450 nm irradiation, a better effect was observed at defective TiO2 surface. At 550 nm, the interface gave the best result due to the surface plasmon resonance. While under the illumination of solar simulator, a combined result was observed. We found that under different excitation wavelengths, the photocatalytic degradation effect at different positions is different, and degradation mechanism is also possibly different. This finding has provided a potential method for further study on the mechanism of photocatalytic degradation of organic pollutants.

原子力红外显微镜 原子层沉积 双酚A 缺陷态氧化钛

Atomic Force-Infrared Microscope Atomic Layer Deposition Bisphenol A Defective titanium oxide

中文

联合培养

南方科技大学

史丽丽. 原位AFM-IR 技术对 TiO2 基光催化降解有机污染物的研究[D]. 深圳. 哈尔滨工业大学,2019.