Ta基复合光催化剂的制备及其性能改性的研究
发布时间：2018-07-16 12:54
【摘要】：半导体光催化技术是一种有前途的方式,能有效地转化太阳能解决加剧的能源短缺和水污染问题,其中,最关键的技术就是开发和利用环保、高效的半导体光催化剂。因此,设计和构建新型、环保的光催化剂将成为解决环境水污染问题的重要研究方向。基于Ta基半导体(Ta_2O_5、Ta_3N_5)丰富的电子结构、良好的物理化学特性和光催化性能等,在光催化领域有很好的应用前景。然而,Ta基半导体的带隙宽、不稳定、光吸收能力差等自身缺陷限制了其光催化性能,无法广泛应用到实际中。因而,本论文旨提高Ta基单体光催化材料的催化性能及其在可见光下的应用,主要设想对Ta基光催化剂(Ta_2O_5、Ta_3N_5)与其他带隙匹配的半导体复合,研究Ta基材料与其它半导体的复合界面和协同效应,并系统地评价复合物降解水体污染物的催化活性和稳定性,探讨该Ta基复合光催化剂的界面电荷传输机理和光催化污染物的降解机制。本论文主要的研究内容和结果如下:(1)首次通过简便的超声分散法成功合成了无定型Ta_2O_5/g-C_3N_4纳米片,结构测试表明无定型的Ta_2O_5均匀分散在g-C_3N_4表面上,从而形成紧密接触的界面。在可见光照射下,相对于无定型Ta_2O_5和g-C_3N_4单体,无定型Ta_2O_5/g-C_3N_4复合物在催化降解RhB时展现了较高的光催化活性。当无定型Ta_2O_5质量比为3%时,Ta_2O_5/g-C_3N_4复合光催化剂拥有最佳的光催化活性(99.14%),降解速率常数是2.0055 h-1,分别是单体Ta_2O_5和g-C_3N_4的6.2和14.9倍。光催化循环实验表明:复合光催化剂具有较高的光稳定性,因而该Ta基复合样品是良好的可重复使用性的。更有趣地是,无定型Ta_2O_5/g-C_3N_4纳米片杂化物的活性更优异于晶型Ta_2O_5/g-C_3N_4。复合光催剂光催化活性的大大提高主要归因于协同效应,包括高比表面积、增强的可见光吸收、有效的界面电荷转移和降低的电荷重组率。在捕获结果的基础上试探性地提出了合理的可见光降解机理。(2)采用简单浸渍法合成新型的Ta_3N_5/g-C_3N_4金属/非金属氮化杂化物,以罗丹明B(RhB)为目标污染物,在可见光下对该杂化物光催化活性的评价,结果显示:Ta_3N_5/g-C_3N_4材料的光催化活性远远高于单体g-C_3N_4的催化活性。当Ta_3N_5与g-C_3N_4质量比为0.02:1时,Ta_3N_5/g-C_3N_4杂化样品拥有最高的光催化效率,其降解速率常数是g-C_3N_4的2.71倍。Ta_3N_5/g-C_3N_4金属/非金属氮化杂化物性能提高主要可归因于Ta_3N_5和g-C_3N_4间的协同作用,拓宽了可见光吸收的范围,提高光生电子和空穴的有效分离速率。另外,该杂化氮化物展现了优异的光稳定性和可重复利用性。自由捕获实验表明光生h+和·OH是无定型Ta_2O_5/g-C_3N_4复合物光催化降解反应中的主要活性物质。(3)通过简单的水热法成功合成了新型Z型Ta_3N_5纳米粒子/锐钛矿TiO_2空心球复合光催化剂。详细研究了Ta_3N_5/TiO_2空心球复合物的形态、光学和光催化特性。有趣的是,当Ta_3N_5纳米粒子和TiO_2空心球耦合,明显拓宽了太阳光的响应范围,提高了降解左氧氟沙星(LEV)的光催化活性。特别地,和单体空心球TiO_2的活性(79.18%)相比,3-Ta_3N_5/TiO_2复合材料不仅拥有稳定、可回收利用的特性,还具有高的LEV光降解活性(97.12%),这可能是因为两者的协同效应,介孔表面和有效的电荷传输性能所致。根据捕获实验和光电流分析,提出了的Z型半导体降解机理。
[Abstract]:Semiconductor photocatalytic technology is a promising way to effectively transform solar energy to solve the problem of energy shortage and water pollution. The key technology is to develop and utilize the environmentally friendly and efficient semiconductor photocatalyst. Therefore, the design and construction of a new type of ring protected photocatalyst will be a solution to the environmental water pollution problem. Based on the rich electronic structure of Ta based semiconductor (Ta_2O_5, Ta_3N_5), good physical and chemical properties and photocatalytic properties, it has a good application prospect in the field of photocatalysis. However, the self physical defects such as wide band gap, instability and poor optical absorption capacity of Ta based semiconductors can not be widely applied to the solid. Therefore, the purpose of this thesis is to improve the catalytic properties of Ta based monomers and their applications in visible light. The main idea is to combine the Ta based Photocatalyst (Ta_2O_5, Ta_3N_5) with other bandgap semiconductors, to study the composite interface and synergistic effect of Ta based materials and other semiconductors, and to systematically evaluate the degradation of the complex body of water. The catalytic activity and stability of the pollutants are discussed and the mechanism of interface charge transfer and the degradation mechanism of photocatalytic pollutants of the Ta based composite photocatalyst are discussed. The main contents and results of this paper are as follows: (1) the amorphous Ta_2O_5/g-C_3N_4 nanoscale was successfully synthesized by a simple ultrasonic dispersion method for the first time, and the structure test showed the amorphous T A_2O_5 is uniformly dispersed on the surface of g-C_3N_4 to form a close contact interface. Under visible light, the amorphous Ta_2O_5/g-C_3N_4 complex exhibits higher photocatalytic activity than the amorphous Ta_2O_5 and g-C_3N_4 monomer in the catalytic degradation of RhB. When the amorphous Ta_2O_5 mass ratio is 3%, the Ta_2O_5/g-C_3N_4 composite photocatalyst is used. With the best photocatalytic activity (99.14%), the rate constant of the degradation is 2.0055 H-1, which is 6.2 and 14.9 times of the monomer Ta_2O_5 and g-C_3N_4 respectively. The photocatalytic cycle experiment shows that the composite photocatalyst has high photostability, so the Ta based composite sample is well reusable. More interestingly, the amorphous Ta_2O_5/g-C_3N_4 Na The activity of the rice hybrids is better than that of the crystalline Ta_2O_5/g-C_3N_4. composite photocatalyst, which is largely attributed to the synergistic effect, including high specific surface area, enhanced visible light absorption, effective interface charge transfer and reduced charge recombination rate. Photodegradation mechanism (2) a new type of Ta_3N_5/g-C_3N_4 metal / nonmetallic nitrided hybrid was synthesized by simple impregnation. The photocatalytic activity of the hybrid was evaluated under visible light with Luo Danming B (RhB) as the target pollutant. The results showed that the photochemical activity of the Ta_3N_5/g-C_3N_4 material was much higher than that of the monomer g-C_3N_4. When Ta_3N_ When the mass ratio of 5 to g-C_3N_4 is 0.02:1, the Ta_3N_5/g-C_3N_4 hybrid sample has the highest photocatalytic efficiency. The degradation rate constant is 2.71 times of g-C_3N_4 and the performance of.Ta_3N_5/g-C_3N_4 metal / non-metallic nitrided hybrids is mainly attributable to the synergism between Ta_3N_5 and g-C_3N_4, which widens the range of visible light absorption and improves the light generating electricity. In addition, the hybrid nitrogen compounds exhibit excellent light stability and reproducibility. Free capture experiments show that h+ and. OH are the main active substances in the photocatalytic degradation of amorphous Ta_2O_5/g-C_3N_4 complexes. (3) a new Z type Ta_3N_5 nanometer was successfully synthesized by a simple hydrothermal method. Particle / anatase TiO_2 hollow sphere composite photocatalyst. The morphology, optical and photocatalytic properties of the Ta_3N_5/TiO_2 hollow sphere complex are studied in detail. It is interesting that the coupling of Ta_3N_5 nanoparticles and TiO_2 hollow spheres greatly widens the response range of the solar light and improves the photocatalytic activity of the degradation of levofloxacin (LEV). Compared with the activity of the body hollow sphere TiO_2 (79.18%), the 3-Ta_3N_5/TiO_2 composites not only have stable, recyclable properties, but also have high LEV photodegradation activity (97.12%), which may be due to the synergistic effect of both, mesoporous surface and effective charge transmission properties. According to the capture experiment and photocurrent analysis, the Z half is proposed. The mechanism of conductor degradation.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36
本文编号：2126454
[Abstract]:Semiconductor photocatalytic technology is a promising way to effectively transform solar energy to solve the problem of energy shortage and water pollution. The key technology is to develop and utilize the environmentally friendly and efficient semiconductor photocatalyst. Therefore, the design and construction of a new type of ring protected photocatalyst will be a solution to the environmental water pollution problem. Based on the rich electronic structure of Ta based semiconductor (Ta_2O_5, Ta_3N_5), good physical and chemical properties and photocatalytic properties, it has a good application prospect in the field of photocatalysis. However, the self physical defects such as wide band gap, instability and poor optical absorption capacity of Ta based semiconductors can not be widely applied to the solid. Therefore, the purpose of this thesis is to improve the catalytic properties of Ta based monomers and their applications in visible light. The main idea is to combine the Ta based Photocatalyst (Ta_2O_5, Ta_3N_5) with other bandgap semiconductors, to study the composite interface and synergistic effect of Ta based materials and other semiconductors, and to systematically evaluate the degradation of the complex body of water. The catalytic activity and stability of the pollutants are discussed and the mechanism of interface charge transfer and the degradation mechanism of photocatalytic pollutants of the Ta based composite photocatalyst are discussed. The main contents and results of this paper are as follows: (1) the amorphous Ta_2O_5/g-C_3N_4 nanoscale was successfully synthesized by a simple ultrasonic dispersion method for the first time, and the structure test showed the amorphous T A_2O_5 is uniformly dispersed on the surface of g-C_3N_4 to form a close contact interface. Under visible light, the amorphous Ta_2O_5/g-C_3N_4 complex exhibits higher photocatalytic activity than the amorphous Ta_2O_5 and g-C_3N_4 monomer in the catalytic degradation of RhB. When the amorphous Ta_2O_5 mass ratio is 3%, the Ta_2O_5/g-C_3N_4 composite photocatalyst is used. With the best photocatalytic activity (99.14%), the rate constant of the degradation is 2.0055 H-1, which is 6.2 and 14.9 times of the monomer Ta_2O_5 and g-C_3N_4 respectively. The photocatalytic cycle experiment shows that the composite photocatalyst has high photostability, so the Ta based composite sample is well reusable. More interestingly, the amorphous Ta_2O_5/g-C_3N_4 Na The activity of the rice hybrids is better than that of the crystalline Ta_2O_5/g-C_3N_4. composite photocatalyst, which is largely attributed to the synergistic effect, including high specific surface area, enhanced visible light absorption, effective interface charge transfer and reduced charge recombination rate. Photodegradation mechanism (2) a new type of Ta_3N_5/g-C_3N_4 metal / nonmetallic nitrided hybrid was synthesized by simple impregnation. The photocatalytic activity of the hybrid was evaluated under visible light with Luo Danming B (RhB) as the target pollutant. The results showed that the photochemical activity of the Ta_3N_5/g-C_3N_4 material was much higher than that of the monomer g-C_3N_4. When Ta_3N_ When the mass ratio of 5 to g-C_3N_4 is 0.02:1, the Ta_3N_5/g-C_3N_4 hybrid sample has the highest photocatalytic efficiency. The degradation rate constant is 2.71 times of g-C_3N_4 and the performance of.Ta_3N_5/g-C_3N_4 metal / non-metallic nitrided hybrids is mainly attributable to the synergism between Ta_3N_5 and g-C_3N_4, which widens the range of visible light absorption and improves the light generating electricity. In addition, the hybrid nitrogen compounds exhibit excellent light stability and reproducibility. Free capture experiments show that h+ and. OH are the main active substances in the photocatalytic degradation of amorphous Ta_2O_5/g-C_3N_4 complexes. (3) a new Z type Ta_3N_5 nanometer was successfully synthesized by a simple hydrothermal method. Particle / anatase TiO_2 hollow sphere composite photocatalyst. The morphology, optical and photocatalytic properties of the Ta_3N_5/TiO_2 hollow sphere complex are studied in detail. It is interesting that the coupling of Ta_3N_5 nanoparticles and TiO_2 hollow spheres greatly widens the response range of the solar light and improves the photocatalytic activity of the degradation of levofloxacin (LEV). Compared with the activity of the body hollow sphere TiO_2 (79.18%), the 3-Ta_3N_5/TiO_2 composites not only have stable, recyclable properties, but also have high LEV photodegradation activity (97.12%), which may be due to the synergistic effect of both, mesoporous surface and effective charge transmission properties. According to the capture experiment and photocurrent analysis, the Z half is proposed. The mechanism of conductor degradation.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36
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