Ag@PDA@Au纳米复合材料的制备及表面等离激元诱导硝化反应

发布时间：2018-05-03 14:38

本文选题：表面增强拉曼光谱 + 纳米复合材料　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：表面增强拉曼光谱(SERS)技术广泛应用于检测低浓度的化学和生物分子,近年来基于SERS技术发现了表面等离激元催化反应(SPAC),可以实现普通催化剂不能或难以实现的催化反应。表面等离激元(SP)是金属表面自由电子的谐振荡,激光作用下产生的热电子和热效应可以辅助催化反应研究。本课题基于单颗粒原位SERS技术,研究了表面等离激元诱导硝化反应。由于在硝化反应过程中需要使用硝酸,而常用作SERS基底的银材料抗酸腐蚀的能力较弱,因此对SERS基底进行了改性研究。利用聚多巴胺(PDA)的强粘附性及弱还原性制备了Ag@PDA@Au复合颗粒,研究了聚多巴胺的聚合时间以及氯金酸溶液的浓度对复合颗粒SERS性能的影响,并对制备的复合颗粒进行了SEM、XRD、TEM、EDS、SERS等测试。研究结果表明,当多巴胺的聚合时间为45 min,氯金酸溶液的浓度为10 mmol/L时,复合颗粒的综合性能最好。基于原位SERS技术,以苯硫酚为反应物,以硝酸为硝化剂,在制备的Ag@PDA@Au复合颗粒上研究了苯环的硝化反应。研究发现,随着激光的照射,在1330 cm-1处逐渐出现一个新的拉曼峰,通过密度泛函理论(DFT)计算可知,生成了对硝基苯硫酚(p-NTP)。进一步研究发现,该硝化反应的速率与激光强度成正比,且SERS基底是该硝化反应发生的必要条件。将Ag@PDA@Au复合颗粒、硝酸和苯硫酚的反应体系加热到不同温度,发现随着温度的升高,硝化反应的速度随之加快,从而说明SP在该反应中起到了等离子体热源的作用。作为对比试验,在制备的具有分级结构的金纳米颗粒和银纳米颗粒上进行了上述硝化反应,发现该反应在金纳米颗粒上最先达到稳定,而在银纳米颗粒上达到稳定需要的时间最长,说明金能够降低该硝化反应的能垒。将硝酸钠作为硝化剂,研究了氢离子对该硝化反应的影响,研究发现,氢离子在该反应中起到催化剂的作用,并据此得出了该硝化反应的机理。研究了萘硫酚、半胱氨酸、对氨基苯酚和对甲基苯硫酚的硝化反应,研究发现,反应物分子的基团种类及分子结构能够影响表面等离激元诱导硝化反应的发生。
[Abstract]:Surface enhanced Raman spectroscopy (SERS) technique has been widely used in the detection of low concentration chemical and biological molecules. In recent years, the surface isophosphate catalytic reaction (SPAC) has been discovered based on the SERS technique, which can realize the catalytic reactions which can not be or can not be realized by ordinary catalysts. Surface isophosphoric ion (SPN) is the resonance of free electrons on metal surface. The hot electron and thermal effect produced by laser can assist in the study of catalytic reaction. In this paper, the surface iso-ionization induced nitrification was studied based on single particle in situ SERS technique. Because nitric acid is used in the nitrification process and the acid corrosion resistance of silver material used as SERS substrate is weak, the modification of SERS substrate has been carried out. The Ag@PDA@Au composite particles were prepared by using the strong adhesion and weak reduction properties of PDAs. The effects of polymerization time of PDAs and the concentration of chlorgold acid solution on the SERS properties of the composite particles were studied. The results showed that when the polymerization time of dopamine was 45 minutes and the concentration of chloruronic acid solution was 10 mmol/L, the comprehensive properties of the composite particles were the best. Based on in situ SERS technique, the nitration of benzene ring was studied on the Ag@PDA@Au composite particles prepared by using phenylthiophenol as reactant and nitric acid as nitration agent. It is found that a new Raman peak appears at 1330 cm-1 with laser irradiation. The results of density functional theory (DFT) show that p-nitrophenylthiophenol p-NTP is formed. It is found that the rate of nitrification is proportional to the laser intensity, and the SERS substrate is the necessary condition for the nitrification to take place. When the reaction system of Ag@PDA@Au particles, nitric acid and phenythiophenol was heated to different temperatures, it was found that the rate of nitrification increased with the increase of temperature, which indicated that SP acted as a plasma heat source in the reaction. As a contrast experiment, the above nitrification reaction was carried out on the prepared gold nanoparticles and silver nanoparticles, and it was found that the reaction was first stable on the gold nanoparticles. However, it takes the longest time to achieve stability on silver nanoparticles, indicating that gold can reduce the energy barrier of the nitrification reaction. The effect of hydrogen ion on the nitrification reaction was studied by using sodium nitrate as nitration agent. It was found that hydrogen ion acted as catalyst in the reaction and the mechanism of the nitrification reaction was obtained. The nitration of naphthalene thiophenol, cysteine, p-aminophenol and p-methylphenylthiophenol was studied.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O657.37;TB33

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