非金属掺杂氧化钛中光生载流子的红外光谱研究

发布时间：2018-05-26 16:56

  本文选题：光催化 + 非金属掺杂　； 参考：《中国科学院大学(中国科学院物理研究所)》2017年硕士论文

【摘要】：揭示光催化剂中的电子态的结构对于深刻理解光催化反应过程至关重要。与此同时,电子态结构的改变又和半导体带隙中的缺陷态(局域态)密切相关。本论文从材料中缺陷态所产生的光生载流子为出发点,采用时间分辨红外光谱技术手段,研究了非金属掺杂氧化钛光催化材料的一些基本物理化学性质。其中主要有以下两方面的工作:(1)利用瞬态红外吸收-激发扫描光谱技术对非金属硼掺杂的氧化钛进行了研究。实验发现,对核心含硼的氧化钛样品进行光解水实验,其产氢性能良好,而产氧效果不佳。当我们通过加热的手段将核心的硼移动到氧化钛表面后,其光解水产氧的效果优于核心含硼的样品,但是其产氢的性能大打折扣,不如前者。从红外光谱表征的结果看,是因为核心含硼的样品其价带上方含有大量的深束缚能级,这些能级的存在束缚了光生空穴,使其氧化能力下降。而在表面含硼的样品中其价带上方的深束缚能级被清除,空穴的氧化能力得以保留,但是在表面含硼的样品中表面的硼会成为光生电子的受体,阻止了电子与质子的反应,导致了产氢效果不佳。(2)利用瞬态红外吸收光谱对非金属氮掺杂的氧化钛样品的光生载流子行为进行了初步研究。发现随着掺氮浓度的增加,样品吸收可见光的范围和吸光系数会增加,但同时复合中心也随之增加,因此加快了光生载流子的复合。在硼氮共掺的氧化钛样品(红钛)中,红钛成功实现了可见光的吸收,即使在525nm光激发情况下仍有大量的光生载流子生成并伴有长时间寿命。在此光照条件下,未掺杂的氧化钛及单一掺杂的氧化钛(单纯硼掺杂或氮掺杂)样品产生的光生载流子的数量都没有红钛产生的量多,而且寿命也没有红钛长。
[Abstract]:It is important to reveal the structure of the electronic state in the photocatalyst for a deep understanding of the photocatalytic reaction process. At the same time, the change of electronic state structure is closely related to the defect state (local state) in the semiconductor band gap. In this paper, the basic physical and chemical properties of nonmetallic doped titanium oxide photocatalytic materials are studied by time-resolved infrared spectroscopy (TRS), starting from the photogenerated carriers produced by defective states in the materials. Among them, there are two main aspects: 1) the nonmetallic boron doped titanium oxide has been studied by transient infrared absorption-excitation scanning spectroscopy. It was found that the hydrogen production of titanium oxide samples containing boron was good, but the effect of oxygen production was not good. When the core boron is moved to the surface of titanium oxide by heating, the effect of photodissociation of aquatic oxygen is better than that of the core sample containing boron, but its hydrogen production is not as good as the former. The results of IR spectra show that there are a large number of deep bound energy levels above the valence band of the core samples containing boron. The existence of these energy levels binds the photogenerated holes and decreases the oxidation ability of the samples. The deep bound energy level above the valence band in the sample containing boron on the surface is removed, and the oxidation ability of the hole is preserved. However, the boron on the surface of the sample containing boron on the surface becomes the receptor of photogenerated electrons, which prevents the reaction between the electron and the proton. The photo-carrier behavior of non-metallic nitrogen-doped titanium oxide samples was studied by transient infrared absorption spectroscopy. It is found that with the increase of nitrogen concentration, the range of visible light absorption and the absorption coefficient will increase, but at the same time, the recombination center will also increase, which accelerates the recombination of photogenerated carriers. In the boron nitrogen co-doped titanium oxide (red titanium) samples, the visible light absorption of the red titanium was successfully realized. Even under the 525nm light excitation, a large number of photogenerated carriers were formed with long lifetime. Under these illumination conditions, the number of photogenerated carriers produced by undoped titanium oxide and single doped titanium oxide (pure boron doped or nitrogen doped) samples is not as large as that of red titanium, and the lifetime is not as long as that of red titanium.
【学位授予单位】：中国科学院大学(中国科学院物理研究所)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;O644.1
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本文编号：1938096