纳米材料的湿法合成(DOC)

1、论文中英文摘要作者姓名： 孙旭平论文题目 ：纳米材料的湿化学合成及新颖结构的自组装构建作者简介 ：孙旭平，男， 1972年 08 月出生， 2000年 09月师从于中国科学 院长春应用化学研究所汪尔康研究员，于 2006年 03 月获博士学位。中文摘要围绕论文题目“纳米材料的湿化学合成及新颖结构的自组装构建” ，我们开展了一系列研 究工作。通过湿化学途径，在贵金属纳米粒子及其二维纳米结构和导电聚合物纳米带的合成 方面进行了深入研究。同时，利用界面自组装及溶液自组装技术，构建了一些新颖结构。本 论文研究工作的主要内容和创新点表现在以下几个方面：(1) 首次提出了一步加热法制备多胺化合物保护的贵金

2、属纳米粒子。我们利用多胺化合物(包括聚电解质和树枝状化合物 )作为还原剂和保护剂，直接加热贵金属盐和多胺化合物的混 合水溶液， 在不加入其它保护剂和还原剂的情况下， 一步制备得到了稳定的贵金属金和银 的纳米粒子。我们在实验中发现， 树枝状化合物聚丙烯亚胺能对反应生成的金纳米粒子的 大小及成核和生长动力学进行有效控制。 我们还发现， 室温下直接混合浓的阳离子聚电解 质分支型聚乙烯亚胺和浓的 HAuCl 4 水溶液可得到高浓度的、稳定的胶体金。这种一步合 成法操作简单且方便易行， 是一种制备多胺化合物保护的贵金属纳米粒子的通用方法； 同 时，本方法合成的纳米粒子表面带正电荷，可用作加工纳米粒子功能

3、化薄膜的构建单元。(2) 首次提出了一种无表面活性剂的、 无模板的、 大规模制备导电聚合物聚邻苯二胺纳米带的 新方法。我们通过在室温下直接混合邻苯二胺和 HAuCl 4水溶液，在没有表面活性剂或 “硬 模板”存在的条件下，获得了长度为数百微米、宽度为数百纳米、厚度为数十纳米的聚邻 苯二胺。纳米带的自发形成可归因于反应中生成的金纳米粒子催化的邻苯二胺的一维定向 聚合。本方法方便快速，无需加入表面活性剂或使用“硬模板” ，且可用于大规模制备。 此外，我们通过在室温下直接混合 AgNO3 和邻苯二胺水溶液，也获得了大量的一维纳米 结构，并发现其形貌可通过调节实验参数而改变。我们还发现，当溶液 pH

4、降低时，这些 一维结构将分解成水溶性的低聚体，而如果再次升高pH,这些低聚体又将自组装形成一 维纳米结构。各种数据表明，这种一维纳米结构是由邻苯二胺被 AgNO3 氧化后所生成的 低聚体在溶液中自组装而形成的。(3) 发展了一系列可大量制备沿 (111)晶面优先生长的单晶金二维结构 (包括纳米片及微米盘 ) 的湿化学合成方法。在室温下直接混合 HAuCl 4和邻苯二胺水溶液，我们得到了大量的、 呈六角形的、纳米厚度的单晶金片，其尺寸达 1.5卩m,邻苯二胺和HAuCl 4间的摩尔比是 纳米片形成的关键， 这种纳米片不仅能应用于光学领域， 还可用于加工具有独特机械性能 的新型结构材料。我们通过直

5、接加热浓的 HAuCl4和线型聚乙烯亚胺混合水溶液，也获得 了大量的金纳米单晶片，其尺寸可达40卩m,反应物浓度是获得纳米片的关键因素， 这种 具有大的(111)晶面的单晶金片有望用做扫描隧道显微镜(STM)的基底。此外，通过加热草 酸-HAuCl4混合水溶液，我们还得到了大量的、尺寸达 4卩m的、呈六角形的金二维结构， 但其厚度大于100 nm,为微米盘，其大小和厚度可通过草酸的用量得到控制。(4) 发展了一种基于溶液中的配位组装的、室温下方便合成有机-无机配位聚合物杂化材料的单分散亚微米胶体球的新方法。在室温下直接混合H2PtCl6和对苯二胺水溶液，通过对苯二胺和PtCl62-在溶液中的配

6、位自组装，我们得到了亚微米尺寸的、单分散的、配位聚合物 球形胶体球。 实验表明， 粒子大小和多分散度可由反应物间的摩尔比和浓度进行控制， 获 得单分散胶体球的最佳实验条件是 1:1 摩尔比和适中的浓度。 本研究结果具有比较重要的 意义：(1) 它提供了一个温和的、室温条件下获得单分散胶体粒子的合成方法，从而避免 了获得单分散的无机材料胶体粒子所必须的高温反应条件； (2) 这种胶体粒子是一种新的 杂化材料，它结合了两种组分的优点而具有多种属性，因而可用在许多领域； (3) 这种胶 体粒子在强还原剂如NaBH4存在的情况下，由于其中的Pt阳离子组分被还原而发生分解， 因此可用做易分解的胶体粒子模

7、板加工中空球。 此外，我们通过室温下直接混合邻苯二胺 的N-甲基吡咯烷酮溶液和 AgNO3水溶液，得到了亚微米的球形银胶体粒子(平均粒径达 850 nm)。实验结果还表明，升高温度有利于更大尺寸的银粒子的生成，溶剂对纯的银粒 子沉淀物的获得起着比较关键的作用。这些亚微米粒子的形成经历了两个阶段： (1) 超饱 和溶液中纳米主粒子的成核； (2) 形成的主粒子聚集成更大的均匀的粒子。我们发展了一种在表面巯基功能化的电极表面有效固定Ru(bpy)32+的新方法。本方法同时运用了溶液自组装和固体表面自组装两种技术，即：先将Ru(bpy)32+和柠檬酸根阴离子保护的金纳米粒子的水溶液按照一定比例混合，

8、得到了 Ru(bpy)32+-金纳米粒子聚集体，然后把少量聚集体的悬浮液直接滴在表面巯基功能化的电极表面，从而实现Ru(bpy)32+在电极 表面的有效固定。 该方法简单易行， 制备的电极具有很好的稳定性和电化学发光性能， 因 而在固态电化学发光检测方面具有很好的应用前景； 此外，该方法还可用于在固体表面构 建 Au 纳米粒子多层膜。 发展了一种通过加热 3-噻吩丙二酸(3-thiophenemalonic acid, TA)和H2PtCl6混合水溶液直 接制备小的Pt纳米粒子的新方法，并通过对该胶体溶液用Ru(bpy)32+处理，得到了2+Ru(bpy)3 -Pt纳米粒子聚集体。通过对在裸电

9、极表面的聚集体进行循环电势扫描，使得聚 集体中的 TA 分子发生电化学聚合而在电极表面形成了稳定的聚合物膜； 由于该膜有效地 避免了聚集体从电极表面脱落， 从而我们得到了非常稳定的、 具有极好电化学发光性能的 膜。本工作不但提供一种方便制备 Pt 纳米粒子的新途径，而且还发展了一种在任何表面 直接加工电化学发光检测器的新方法，在固态电化学发光检测方面具有重要应用价值。通过在室温下直接混合H2PtCl6和Ru(bpy)3Cl2水溶液，我们获得了具有新颖形貌的、含有 Ru(bpy)32+的微结构。实验结果表明，金属价态、金属种类及反应物摩尔比和浓度对微结 构的形貌有重要影响， 形成的微结构都具有很

10、好的电化学发光性能。 这些微结构给我们提 供了一种新的功能材料， 将在毛细管电泳或毛细管电泳微芯片的固态电化学发光检测方面 有着很好的应用前景。关键词： 纳米材料，湿化学，自组装，电化学发光Wet-Chemical Routes to the Preparation of Namomaterials andSelf-Assembly-Based Fabrication of Novel StructuresSun XupingABSTRACTBoth the wet-chemical preparation of nanomaterials and self-assembly-based fa

11、brication of novel structures have been paid considerable attention. We carried out several studies on the preparation of noble metal nanoparticles and its two-dimensional nanostructures and conducting polymers nanobelts via wet-chemical routes. On the other hand, we fabricated some novel structures

12、 through self-assembly on planar solid substrates or in solutions. Especially, the application of some structures in the field of solid-state electrochemiluminescence detection is also explored.We have developed a heat-treatment-based strategy for the one-step preparation of polyamine-protected nobl

13、e metal nanoparticle. With the use of third-generation poly(propyleneimine) (PPI G3) dendrimer to simultaneously act both as the reducing agent and protective agent, stable noble metal gold nanoparticles have spontaneously formed by heating a solution containing HAuCl 4 and PPI G3. As a result, an a

14、dditional step of introducing a reducing agent as well as a protective agent is no longer needed. It is found that the size, the nucleation and growth kinetics of the gold nanoparticles thus formed can be tuned by changing the initial molar ratio of PPI G3 to gold. Similarly, highly stable Ag nanocl

15、usters with narrow size distribution have been prepared by heating a AgNO 3/PPI G3 aqueous solution without the additional step of introducing other reducing agents and protect agents. It is found that as-obtained particle is in coexistence of Ag and Ag2O and increasing temperature results in both t

16、he decrease in number of small particles and the increase in size of large particles. In addition, such thermal process has been successfully used to prepare amine-functionalized polyelectrolyte-protected gold nanoparticles by directly heating an aqueous solution containing HAuCl4 and polyelectrolyt

17、es. Four polyelectrolytes including N-3-(trimethoxysilyl)propylpolyethylenimine (Si-PEI), branched polyethylenmine(BPEI), linear polyethylenimine (LPEI) and poly(allylamine hydrochloride) (PAH) were used in our study and well-stabilized gold nanoparticles with relatively narrow size distribution wer

18、e obtained. Because gold nanoparticles thus formed can be combined with the properties of the polyelectrolytes used, they hold promise for use in the biomedical and bioanalytical field and on the other hand, as building blocks for the creation of nanoparticles-containing thin films. This strategy wi

19、ll be general to other polyelectrolytes with the same chemical structure as these four polyelectrolytes used and to the preparation of other nanoparticles such as Ag nanoparticles. Furthermore, we have found that highly concentrated, well-stable gold colloids can be prepared by direct mix of concent

20、rated HAuCl 4 and BPEI aqueous solutions at room temperature.We have developed for the first time a novel but simple surfactantless, templateless method for preparing conducting polymer poly( o-phenylenediamine) nanobelts on a large scale. The mix of HAuCl 4 and o-phenylenediamine aqueous solutions

21、at room temperature results in the formation of a large quantity of precipitate. Lower magnification scanning electron microscopy (SEM) image indicates that the precipitate consists of a large quantity of uniform one-dimensional structures. Higher magnification SEM image further reveals these struct

22、ures are transparent nanobelts with several hundred micrometers in length, several hundred nanometers in width, and several ten nanometers in height. Also observed in these SEM images are a number of nanoparticles. The X-ray diffraction (XRD) analysis of the resulting precipitate reveals the formati

23、on of amorphous poly(o-phenylenediamine) polymers with larger crystalline size as well as crystalline gold. Elemental analysis of the resulting precipitate using secondary electrons by SEM indicates the belts are poly(o-phenylenediamine) polymers but the particles are gold particles. The possible fo

24、rmation of the nanobelts can be explained as follows: The reduction of HAuCl 4 by o-phenylenediamine leads to the formation of gold nanoparticles with the occurrence of o-phenylenediamine oligomers first, then gold nanoparticles produced serve as active catalysts to catalyze the oriented oxidative p

25、olymerization of other o-phenylenediamine monomers by HAuCl4 along the oligomers produced, resulting in the formation of poly( o-phenylenediamine) nanobelts. Furthermore, we have found that mixing of AgNO 3 and o-phenylenediamine in aqueous medium results in the formation of uniform one-dimensional

26、structures. However, the formation of such 1D structure involves the following two stages: (1) The oxidation of o-phenylenediamine by AgNO3 leads to the formation of individualo-phenylenediamine oligomers. (2) The resulting individual oligomers self-assembly to form uniform larger 1D structures. Int

27、erestingly, decreasing medium pH can break these 1D structures apart to form individual oligomers, or vice versa. It is also found that both the concentration and molar ratio of reactants have considerable influences on the morphologies of the structures thus formed.We have developed several wet-che

28、mical approaches for the large-scale preparation of two-dimensional, single-crystalline gold structures including nanoplates and microdisks. The mix of an appropriate volume of an aqueous solution of freshly preparedo-phenylenediamine and HAuCl4 at room temperature with 1:1 molar ratio of o-phenylen

29、ediamine to gold gradually leads to a large quantity of precipitate, which is collected by centrifugation, washed several times with THF and water, and then suspended in water. The lower magnification SEM image indicates that the precipitate consists of a large amount of particles, while the higher

30、magnification SEM image clearly reveals that the particles are micrometer-scale plates (about 1.5 pm in size), mainly hexagonal in shape. The distance between two planes of one plate standing against the glass substrate indicates that these plates are nanoplates. The corresponding energy-dispersive

31、X-ray spectrum (EDS) shows these nanoplatesare pure metallic gold. Two surface plasmon absorption bands at about 680 and 925 nm which arise from the longitudinal plasmon resonanceof gold particles are observed for these gold nanoplates, providing another piece of evidence for the formation of anisot

32、ropic gold particles. It suggests that the quantity of o-phenylenediamine in the solution is crucial to yielding gold nanoplates and we may suggest that o-phenylenediamine molecules serve as a soft template and kinetically control the growth rates of various faces of gold particles by selectively ad

33、sorbing on to the crystallographic planes, thus resulting in the formation of large single-crystalline gold nanoplates. The importance of the platelet-like gold particles is not restricted to optics; exceptionally interesting materials with unique mechanical properties can be obtained with such coll

34、oids. A polyamine process has also been successfully used for the high-yield preparation of single-crystalline gold nanoplates with several 10pm in size, mainly hexagonal in shape, carried out by heating a concentrated aqueous solution of LPEI and HAuCh at 100 °C . The following experimental fa

35、cts (1) there are no gold byproducts with other shapes except the nanoplates existing in the resulting products and (2) adding NaBH4 to the colorless supernatant after the termination of reaction gives no gold particles due to the depletion of HAuCl4 in the mixture by LPEI indicate that this heat-tr

36、eatment-basedpolyamine process is a high-yield approach for the preparation of large gold nanoplates. It is found that the concentration of reactants is crucial to the formation of nanoplates. As-prepared gold nanoplates with a large Au(111) face may hold promise for scanning tunneling microscopy (S

37、TM) substrates. Furthermore, heating an aqueous oxalic acid/HAuCl 4 solution has been proven to be an effective and facile approach for the large-scale production of microsized, single-crystalline, hexagonal gold microplates with a thickness above 100 nm. Both the size and the thickness of these pla

38、tes can be controlled by the molar ratio of oxalic acid to gold. It is also found that the concentration of reactants strongly influences the formation of the gold plates.We have demonstrated a novel coordination-based strategy to the fabrication of submicrometer-scale,monodisperse,spherical colloid

39、s of organic-inorganic hybrid materials. The mix of p-phenylenediamine and H 2PtCl 6 aqueous solutions at room temperature results in the formation of a large amount of precipitate. Low magnification SEM image of as-prepared precipitate indicates that the precipitate consists of a large quantity of

40、monodisperse, submicrometer-scale particles about 420 nm in diameter. Higher magnification SEM image reveals that these particles are spherical in shape and well-separated from each other, and a local magnification of a single colloidal sphere by transmission electron microscopy (TEM) indicates that

41、 the resulting particles have electron-microscopically perfectly smooth surface. The chemical composition of the resulting colloids was determined by energy-dispersed spectrum (EDS) and the occurrence of the peaks of Pt, Cl, C, and N indicates that the colloids are products of p-phenylenediamine and

42、 H2PtCl6. A possible formation processis briefly presented as following:2-When p-phenylenediamine and PtCl6 are mixed together, the two nitrogen atoms on the para positions of one p-phenylenediamine aromatic ring can coordinate to two different Pt(IV) cations, resulting in p-phenylenediamine-bridged

43、 structure, and the Pt species contained in as-formed structure can further capture other p-phenylenediamine molecules by coordination interactions along different directions. This coordination-induced assembly process can proceed repeatedly until the depletion of reactants in the solution, resultin

44、g in the formation of large coordination polymers, finally. It is found that the particle size and polydispersity can be controlled by the molar ratio and concentration of reactants, however, the optimum experimental parameters for the production of monodispersecolloids are 1:1 molar ratio and moder

45、ate concentration of the two reactants. Our observations are significant for the following reasons. (1) It provides a mild, room temperature route to fine colloids, avoiding the use of high temperature, which is crucial to the formation of fine colloids of inorganic materials. (2) Such colloids are

46、new hybrid materials with versatile properties provoked by combining the merits of two sources and may find applications in many fields. (3) Such colloids are easily broken up by a strong reducing reagent, such as NaBH4, becauseof the reduction of the Pt cations contained therein, and therefore, the

47、y hold promise as easily decomposable colloidal templates for the fabrication of hollow spheres for a variety of applications. We have also demonstrated the rapid preparation of uniform, large, spherical Ag spheres with relatively low polydispersity through a simple wet-chemical route. The formation

48、 of Ag particles with about 750 nm in diameter occurs in a single process, carried out by direct mix of AgNO 3 aqueous solution and o-phenylenediamine N-methyl-2-pyrrolidone (NMPD) solution at room temperature. The formation of monodisperse Ag colloids in our previous study can be explained as follo

49、ws: AgNO 3 is reduced by o-phenylenediamine to form metallic Ag atoms. With elapsed time, new Ag atoms are generated in this system and nucleation occurs as the concentration of Ag atoms reaches critical supersaturation, resulting in the formation of nuclei. The nuclei grow to nanoscale primary part

50、icles by further addition of Ag atoms, and then the primary particles aggregate to form large Ag spheres with relatively narrow size distribution. It is found that that increasing temperature results in increasing particle size. We have found that the mix of AgNO 3 and o-phenylenediamine aqueous sol

51、utions, under otherwise identical conditions, yields precipitate consisting of a large quantity of large spherical Ag particles and belt-shaped structurescorresponding to the oxidative products of o-phenylenediamine by AgNO 3. NMPD is a powerful solvent with low toxicity and broad solubility, comple

52、tely soluble in water at all temperatures and soluble in most organic solvents. We therefore choose NMPD in our present study as an effective cosolvent to dissolve the oxidative products of o-phenylenediamine in a timely manner, preventing them from precipitating with Ag particles and leading to the

53、 formation of pure Ag spheres.We have developed a novel method based on both solution- and planar solid substrate-based 2+assembly techniques for effective immobilization of Ru(bpy)3 on sulfhydryl-derivated electrode surfaces for solid-state electrochemiluminescenedetection application. The whole im

54、mobilization2+process involves the following two steps: (1) The addition of Ru(bpy)3 cations into citrate-capped gold nanoparticles (AuNPs) solution results in the formation of a Ru-AuNPs precipitate due to 2+electrostatic interactions-driven assembly of the positively charged Ru(bpy)3 cations and t

55、he negatively charged citrate ions coating on the AuNPs; (2) The suspension of Ru-AuNPs was placed on the sulfhydryl-derivated ITO electrode surface. The energy-dispersedspectrum (EDS) of the 2+resulting precipitate indicates the precipitate consists of Ru(bpy3) and AuNPs. The absence of the peak of

56、 S element in the EDS may be attributed to the following two reasons: (1) The content of S element itself is too low to be detected. (2) The sulfhydryl groups are located below the Ru-AuNPs film, and the substrate is nearly completely covered by the Ru-AuNPs film. It is found that the modification o

57、f substrate with sulfhydryl group and the resultant strong Au-S interactions between sulfhydryl group and AuNPs are crucial to the effective immobilization of such Ru-AuNPs on the surface and there is no stable film formed on bare ITO surface. The Ru-AuNPs-modified ITO electrode is quite stable, exh

58、ibits excellent electrochemiluminescene behavior, and hence holds great promise for solid-state electrochemiluminescene detection in capillary electrophoresis (CE) or 2+ a CE microchip. It provides a new methodology for fabrication of stable Ru(bpy)3 -containing structures on a solid electrode surfa

59、ce for solid-state electrochemiluminescene detection and, on the other hand, also provides an interesting method of immobilization of nanoparticles on the surfaces for applications.We have developed a simple thermal process for the preparation of small Pt nanoparticles, carried out by heating a H2PtCl6/3-thiophenemalonic acid (TA) aqueous solution without the addition of other reducing agents and protective agents. The formation of such Pt nanoparticles can be 2- attributed to the direct redox between T