【作者】 卢伟伟；

【导师】 王键吉；

【作者基本信息】 兰州大学 ， 物理化学， 2009， 博士

【摘要】 由于具有区别于块状材料的独特性质,纳米材料在催化、电子器件、信息存储、光学器件、生物传感、微区成像以及医药等方面具有巨大的应用潜力。近年来在通过控制纳米粒子的尺寸和形貌来调节其性质并应用于某些领域方面取得了巨大的进步。但随着对环境保护的日益关注,寻求更加绿色、高效的纳米材料合成方法仍然是一项具有挑战性的工作。本文采用相对绿色的方法,分别合成了三角形Ag纳米片、Ag/ZnO纳米棒和Ag/ZnO中空微球。在制备过程中,应用了新型绿色溶剂离子液体和生物相容材料如抗坏血酸、酪氨酸和海藻酸钠等。并且所制备的材料在抗菌、表面增强拉曼散射（surface enhanced Raman scattering,SERS）检测和光催化降解环境污染物等方面表现出了优异的性能。本文各章的主要内容如下:第1章,简要综述了纳米材料绿色合成的研究进展,主要包括绿色溶剂、生物合成和绿色制备工艺三个方面。第2章,利用[C₆mim][PF₆]-H₂O体系制备了三角形Ag纳米片,并利用XRD、TEM和SAED等手段对其结构进行了表征,最后对三角形Ag纳米片的抗菌性能和作为SERS活性基体检测4-氨基硫酚进行了研究。结果表明,降低Ag⁺的还原速度而使得合成过程受动力学控制是成功合成三角形Ag纳米片的决定因素;结构表征证实,Ag纳米片的上下两个底面为{111}面,晶体结构中面缺陷的存在导致了SAED中1/3{422}衍射斑点的存在,而其表面的明暗条纹则是由纳米片的弯曲变形引起的;由于大量高活性{111}面的存在,所制备的Ag纳米片表现处了良好的抗菌性能,其最小抑菌浓度（minimuminhibition concentration,MIC）值对格氏阴性的Escherichia coli和格氏阳性的Staphylococcus aureus分别为15和20μg/mL;以Ag纳米片作为SERS活性基体,可检测到溶液中浓度仅为10^-7M的4-氨基硫酚,电磁场增强和电子转移都对SERS信号的增强起到重要的作用。第3章,采用水热合成的方法制备了Ag/ZnO复合纳米棒,利用XRD、SEM、FEM和XPS等对其结构进行了表征,并对其抗菌活性和光催化降解橙黄G的性能进行了研究。结果表明,酪氨酸不仅是Ag⁺离子的还原剂而且是Ag/ZnO纳米棒的结构导向剂,制备过程中酪氨酸的浓度和加入氨水的体积对样品的形貌影响较大。结构表征显示,Ag/ZnO为有侧面的纳米棒并且Ag纳米粒子镶嵌在ZnO的表面。在Ag/ZnO纳米棒光催化降解橙黄G的过程中,由于Ag纳米粒子作为电子池有效地阻止了光致电子-空穴的复合,从而大大提高了Ag/ZnO纳米棒的光催化性能。而在抗菌过程中,由于金属Ag和半导体ZnO之间的强相互作用,使得Ag纳米粒子带部分正电荷,此外由于ZnO纳米棒起到Ag纳米粒子载体的作用,而使Ag/ZnO复合材料表现出协同的高效抗菌性能。第4章,采用水热合成的方法制备了3D的Ag/ZnO中空微球,对其结构进行了表征,并研究了海藻酸钠和氨水的加入量对3D中空微球形成的影响,最后对其光催化降解橙黄G的性能进行了研究。结构表征显示,3D的Ag/ZnO中空微球是由Ag/ZnO纳米棒沿着其生长方向垂直于微球表面而定向排列所组成的,Ag纳米粒子除了起到分离电子-空穴的作用外,还起到调节ZnO表面羟基含量的作用。因此,在合适的Ag含量时,Ag/ZnO中空微球表现出良好的光催化降解性能。第5章,总结了本文主要研究成果和存在的不足,并就下一阶段将要开展的研究工作进行了展望。更多还原

【Abstract】 Due to a range of fascinating properties,nanocrystals have been applied in catalysis,electronics,information storage,photonics,sensing,imaging,medicine and among others.In recent years,much success have been made to control the poperties of nanomaterials with aprropriate size and shape for efficient utilization in some fields.However,with the increasing concern to the enviromental,it still remains a great challenge to develop the facile,clean and high-yield synthesis methods for nanomaterials.In this paper,some greener methods have been developed to synthesize the nanocystals of triangular Ag nanoplates and Ag/ZnO nanocomposites.In the preparation process,the green solvent of ionic liquids and the biocompatible materials such as ascorbic acid,tyrosine and sodium alginate have been used. Fouthermore,their enviromental applications in anti-bacteria,SERS detection and degradation of dye pollutants are also studied.The main contents of each chapter are as follows.Chapter 1.The progress in the green preparation of nanomaterials,such as the use of green solvent,the biopreparion and the clean process,are reviewed.Chapter 2.The triangular Ag nanoplates were prepared from a [C₆mim][PF₆]-H₂O two phase systerm.Then the structures of the prepared Ag nanoplates were characterized by XRD,TEM,and SAED.Finally,their antibacterial activities for both Escherichia coli and Staphylococcus aureus were evaluated and their applications as active substrate for SERS detection of 4-ATP were also examined.The results show that,the slow reduction of Ag⁺made the process kinetically controlled for formation of triangular Ag nanoplates.The observations from TEM and SAED suggested that the upper and lower bases were bound by{111}planes and the l/3{422}spots were originated from the planar defects.However,the dark bands on the surface in TEM observation were from the bending countour.Due to the increase of the {111}active planes,the Ag nanoplates showed a better antibacterial effect than Lee-meisal Ag,and the MIC values for Escherichia coli and Staphylococcus aureus were found to be 15 and 20μg/mL,respectively.As the SERS active substrates,the Ag nanoplates can detect 4-ATP at the concentration of 10^-7M,and the SERS signals envolved the mechanism of the electromagnetic enhancement and the chemical effects of charge transfer.Chapter 3.The ID Ag/ZnO nanorod were prepared though a facile one-pot hydrothermal method.The prepared samples were structurally characterized by XRD,SEM,TEM,and XPS.Then,their photocatalytic performance for degradation of Orange G and their antibacterial activities were evaluated, respectively.It was shown that the added tyrosine served both as a reducing agent of Ag+ion and as a shape conductor for the formation of ZnO faceted nanorods, and that the concentration of tyrosine and the volume of the added ammonia solution significantly influence the final morphology of the products.The structure characterizations indicated that the Ag nanoparticles were embedded in the ZnO nanorods.In the photocatalytic process under UV irradiation,Ag nanoparticles on the ZnO surface may serve as electron sinks,promoting the separation of photogenerated electron-hole pairs,and thus increased their photocatalytic activity. While in antibacterial tests,the nanocomposites showed enhanced and synergistic antibacterial activities for both gram-negative and gram-positive bacteria,due to the strong interaction between metallic Ag and semiconductor ZnO.Chapter 4.Firstly,the Ag modified three-dimensional（3D）ZnO hollow microspheres were prepared through a facile one-step hydrothermal method.Then the as-prepared samples were structurally characterized by XRD,FESEM, HRTEM and XPS.The influence of deposited Ag on the electronic structure and surface property of ZnO had been emphasized.Finally,the photocatalytic performance of the prepared Ag/ZnO samples with different Ag contents for the degradation of Orange G was systematically explored.The structural characterizations showed that the wall of the hollow microsphere is composed of oriented nanorods,which were aligned with their growth axes perpendicular to the surface of the microsphere.In addition to the effects of enhanced separation of the photogenerated electron-hole pairs,Ag deposits with appropriate contents also increased the surface hydroxyl contents of ZnO microspheres.This facilitated the trapping of the photoinduced electrons and holes to form more active hydroxyl radicals,and thus enhanced the photocatalytic efficiency of ZnO.更多还原