氧化银基半导体复合材料制备及其光催化性能研究
发布时间：2019-02-28 07:38
【摘要】：太阳能是解决能源和环境危机的重要可再生能源。利用太阳能进行环境修复和能源转化已经引起全球学者广泛关注,其中使用半导体材料催化剂捕获和转化太阳能应用潜力巨大。但是,现有光催化剂的量子效率仍然十分有限。因此,开发新型半导体光催化剂,提高太阳能转化效率仍然是光催化研究的热点。氧化银禁带宽度较窄,具有较高的可见光利用率,已经受到研究者的越来越多的关注。但是,氧化银激发后生成的电子空穴对极易复合,这限制了它的规模化应用。而负载助催化剂构建复合体系是提高光生电子空穴对分离和迁移效率行之有效的方法。在本论文中,通过温和的湿化学法,成功制备了Ag_2O/NaTaO_3、AgCl/Ag_2O/NaTaO_3和Ag/AgCl/Ag_2O三种纳米复合光催化剂,抑制了氧化银光生电子空穴对的复合,提高了其光催化效率。取得的具体研究结果如下:(1)利用湿化学沉积法制备了可见光响应Ag_2O/NaTaO3 p-n异质结复合光催化剂,通过p-n异质结之间的界面电子单向传递,抑制了氧化银光生电子空穴对复合。通过XRD、SEM和TEM等分析测试手段对Ag_2O/NaTaO3复合材料晶体结构和形貌等进行了表征。以罗丹明B为降解对象,考察了复合材料的光催化性能。根据捕获实验和能带相对位置,提出了复合材料催化降解机理。(2)利用的简便的湿化学方法合成了AgCl/Ag_2O/NaTaO3三元复合催化剂。AgCl的加入,不仅引入Cl0自由基作为新活性物种,而且还增加Ag_2O光生电子新的转移途径,进而提高复合材料的光催化效率。AgCl/Ag_2O/NaTaO3复合光催化剂在可见光下对罗丹明B染料的具有很高的光催化降解活性。根据实验结果,提出了复合材料催化降解机理。(3)利用原位生长法制备了Ag/AgCl/Ag_2O纳米复合催化剂。通过Ag纳米粒子的等离子共振效应和AgCl的电子传递作用,提高了Ag_2O电子空穴对的分离效率。Ag/AgCl/Ag_2O复合催化剂对于光催化降解环丙沙星展现出很高的光催化活性。当Ag/AgCl摩尔比例为50%时,复合催化剂对环丙沙星的降解效率最高,分别是Ag_2O和Ag/AgCl的2.9倍和3.73倍。通过捕获实验验证光催化反应活性基团,提出一种具有等离子共振效应的Z字型机理。
[Abstract]:Solar energy is an important renewable energy to solve the energy and environmental crisis. The use of solar energy for environmental remediation and energy conversion has attracted worldwide attention, among which the use of semiconductor catalysts to capture and convert solar energy has great potential. However, the quantum efficiency of the existing photocatalysts is still very limited. Therefore, the development of new semiconductor photocatalysts and the improvement of solar energy conversion efficiency are still the focus of photocatalysis research. More and more attention has been paid to silver oxide with narrow band gap and high utilization of visible light. However, the electron hole pairs generated by silver oxide excitation are easy to composite, which limits its large-scale application. It is an effective method to improve the efficiency of photogenerated electron hole separation and migration by building a composite system with supported cocatalyst. In this paper, three kinds of nano-composite photocatalysts Ag_2O/NaTaO_3,AgCl/Ag_2O/NaTaO_3 and Ag/AgCl/Ag_2O were successfully prepared by mild wet chemical method, which inhibited the recombination of photogenerated electron-hole pairs of silver oxide. The photocatalytic efficiency was improved. The results are as follows: (1) visible light-responsive Ag_2O/NaTaO3 heterojunction composite photocatalysts were prepared by wet chemical deposition. The recombination of photogenerated electron-hole pairs of silver oxide was inhibited. The crystal structure and morphology of Ag_2O/NaTaO3 composites were characterized by XRD,SEM and TEM. The photocatalytic properties of the composites were investigated by using Rhodamine B as the degradation object. Based on the capture experiment and the relative position of the energy band, the catalytic degradation mechanism of the composites was proposed. (2) the AgCl/Ag_2O/ NaTaO3 ternary composite catalyst was synthesized by a simple wet chemical method. Cl0 radical is not only introduced as a new active species, but also increases the new electron transfer pathway of Ag_2O photogeneration. AgCl / Ag_2O/NaTaO3 composite photocatalyst has high photocatalytic degradation activity for Rhodamine B dye under visible light. Based on the experimental results, the catalytic degradation mechanism of the composites was proposed. (3) Ag/AgCl/Ag_2O nano-composite catalysts were prepared by in-situ growth method. The separation efficiency of Ag_2O electron-hole pair was improved by plasma resonance effect of Ag nanoparticles and electron transfer of AgCl. AG / AgCl/Ag_2O composite catalyst showed high photocatalytic activity for photocatalytic degradation of ciprofloxacin. When the molar ratio of Ag/AgCl was 50%, the degradation efficiency of ciprofloxacin was the highest, which was 2.9 times and 3.73 times higher than that of Ag_2O and Ag/AgCl, respectively. A Z-shaped mechanism with plasmon resonance effect was proposed by validating the active groups in the photocatalytic reaction by capture experiments.
【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：2431627
[Abstract]:Solar energy is an important renewable energy to solve the energy and environmental crisis. The use of solar energy for environmental remediation and energy conversion has attracted worldwide attention, among which the use of semiconductor catalysts to capture and convert solar energy has great potential. However, the quantum efficiency of the existing photocatalysts is still very limited. Therefore, the development of new semiconductor photocatalysts and the improvement of solar energy conversion efficiency are still the focus of photocatalysis research. More and more attention has been paid to silver oxide with narrow band gap and high utilization of visible light. However, the electron hole pairs generated by silver oxide excitation are easy to composite, which limits its large-scale application. It is an effective method to improve the efficiency of photogenerated electron hole separation and migration by building a composite system with supported cocatalyst. In this paper, three kinds of nano-composite photocatalysts Ag_2O/NaTaO_3,AgCl/Ag_2O/NaTaO_3 and Ag/AgCl/Ag_2O were successfully prepared by mild wet chemical method, which inhibited the recombination of photogenerated electron-hole pairs of silver oxide. The photocatalytic efficiency was improved. The results are as follows: (1) visible light-responsive Ag_2O/NaTaO3 heterojunction composite photocatalysts were prepared by wet chemical deposition. The recombination of photogenerated electron-hole pairs of silver oxide was inhibited. The crystal structure and morphology of Ag_2O/NaTaO3 composites were characterized by XRD,SEM and TEM. The photocatalytic properties of the composites were investigated by using Rhodamine B as the degradation object. Based on the capture experiment and the relative position of the energy band, the catalytic degradation mechanism of the composites was proposed. (2) the AgCl/Ag_2O/ NaTaO3 ternary composite catalyst was synthesized by a simple wet chemical method. Cl0 radical is not only introduced as a new active species, but also increases the new electron transfer pathway of Ag_2O photogeneration. AgCl / Ag_2O/NaTaO3 composite photocatalyst has high photocatalytic degradation activity for Rhodamine B dye under visible light. Based on the experimental results, the catalytic degradation mechanism of the composites was proposed. (3) Ag/AgCl/Ag_2O nano-composite catalysts were prepared by in-situ growth method. The separation efficiency of Ag_2O electron-hole pair was improved by plasma resonance effect of Ag nanoparticles and electron transfer of AgCl. AG / AgCl/Ag_2O composite catalyst showed high photocatalytic activity for photocatalytic degradation of ciprofloxacin. When the molar ratio of Ag/AgCl was 50%, the degradation efficiency of ciprofloxacin was the highest, which was 2.9 times and 3.73 times higher than that of Ag_2O and Ag/AgCl, respectively. A Z-shaped mechanism with plasmon resonance effect was proposed by validating the active groups in the photocatalytic reaction by capture experiments.
【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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