氧化銀基半導(dǎo)體復(fù)合材料制備及其光催化性能研究
發(fā)布時(shí)間：2019-02-28 07:38
【摘要】：太陽(yáng)能是解決能源和環(huán)境危機(jī)的重要可再生能源。利用太陽(yáng)能進(jìn)行環(huán)境修復(fù)和能源轉(zhuǎn)化已經(jīng)引起全球?qū)W者廣泛關(guān)注,其中使用半導(dǎo)體材料催化劑捕獲和轉(zhuǎn)化太陽(yáng)能應(yīng)用潛力巨大。但是,現(xiàn)有光催化劑的量子效率仍然十分有限。因此,開(kāi)發(fā)新型半導(dǎo)體光催化劑,提高太陽(yáng)能轉(zhuǎn)化效率仍然是光催化研究的熱點(diǎn)。氧化銀禁帶寬度較窄,具有較高的可見(jiàn)光利用率,已經(jīng)受到研究者的越來(lái)越多的關(guān)注。但是,氧化銀激發(fā)后生成的電子空穴對(duì)極易復(fù)合,這限制了它的規(guī)模化應(yīng)用。而負(fù)載助催化劑構(gòu)建復(fù)合體系是提高光生電子空穴對(duì)分離和遷移效率行之有效的方法。在本論文中,通過(guò)溫和的濕化學(xué)法,成功制備了Ag_2O/NaTaO_3、AgCl/Ag_2O/NaTaO_3和Ag/AgCl/Ag_2O三種納米復(fù)合光催化劑,抑制了氧化銀光生電子空穴對(duì)的復(fù)合,提高了其光催化效率。取得的具體研究結(jié)果如下:(1)利用濕化學(xué)沉積法制備了可見(jiàn)光響應(yīng)Ag_2O/NaTaO3 p-n異質(zhì)結(jié)復(fù)合光催化劑,通過(guò)p-n異質(zhì)結(jié)之間的界面電子單向傳遞,抑制了氧化銀光生電子空穴對(duì)復(fù)合。通過(guò)XRD、SEM和TEM等分析測(cè)試手段對(duì)Ag_2O/NaTaO3復(fù)合材料晶體結(jié)構(gòu)和形貌等進(jìn)行了表征。以羅丹明B為降解對(duì)象,考察了復(fù)合材料的光催化性能。根據(jù)捕獲實(shí)驗(yàn)和能帶相對(duì)位置,提出了復(fù)合材料催化降解機(jī)理。(2)利用的簡(jiǎn)便的濕化學(xué)方法合成了AgCl/Ag_2O/NaTaO3三元復(fù)合催化劑。AgCl的加入,不僅引入Cl0自由基作為新活性物種,而且還增加Ag_2O光生電子新的轉(zhuǎn)移途徑,進(jìn)而提高復(fù)合材料的光催化效率。AgCl/Ag_2O/NaTaO3復(fù)合光催化劑在可見(jiàn)光下對(duì)羅丹明B染料的具有很高的光催化降解活性。根據(jù)實(shí)驗(yàn)結(jié)果,提出了復(fù)合材料催化降解機(jī)理。(3)利用原位生長(zhǎng)法制備了Ag/AgCl/Ag_2O納米復(fù)合催化劑。通過(guò)Ag納米粒子的等離子共振效應(yīng)和AgCl的電子傳遞作用,提高了Ag_2O電子空穴對(duì)的分離效率。Ag/AgCl/Ag_2O復(fù)合催化劑對(duì)于光催化降解環(huán)丙沙星展現(xiàn)出很高的光催化活性。當(dāng)Ag/AgCl摩爾比例為50%時(shí),復(fù)合催化劑對(duì)環(huán)丙沙星的降解效率最高,分別是Ag_2O和Ag/AgCl的2.9倍和3.73倍。通過(guò)捕獲實(shí)驗(yàn)驗(yàn)證光催化反應(yīng)活性基團(tuán),提出一種具有等離子共振效應(yīng)的Z字型機(jī)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.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36
本文編號(hào)：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.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36
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相關(guān)期刊論文 前4條
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