多元醇法合成銀納米線

1、Synthesis of Silver Nanowires Based on the Polyol Method第七組：第七組： 王川王川 邵樂邵樂 殷杰殷杰 吳斌吳斌 劉新玲劉新玲 多元醇法合成銀納米線多元醇法合成銀納米線Synthesis of Silver Nanowires Based on the Polyol MethodOutline:1.The applications of silver nanowires2.Introduction to synthesis of silver nanowires3.Synthesis of silver nanowires based o

2、n the polyol method3.1 Introduction to the polyol method3.2 Mechanism3.3 Improvements of the polyol method3.4 Further research 1.The applications of silver nanowiresDue to some unique properties，including high electrical and thermal conductivities, silver nanowires can be used as:Optical polarizers(

3、偏光器）偏光器）Photonic crystals（光學(xué)晶體）（光學(xué)晶體）Biomdeidcal and chemical sensorCatalystsJie Yao, et al.Science,2008,321,930Silver nanowires rafts for trace analysisOptical negative refraction2.Introduction to synthesis of silver nanowires Approaches for synthesis of silver nanowires generally fall into one of

4、two categories: Template-directed Templates including porous alumina membranes, carbon nanotubes, DNA chains, rod-shaped micells Template-free Wet chemical methods, vapor-phase synthesisEG (ethylene glycol 乙二醇乙二醇)AgNO3PVP( polyvinylpyrrolidone 聚乙烯吡咯烷酮聚乙烯吡咯烷酮) Injected using a two-channel syringe pum

5、p at a rate of 0.3 mL/min3.1 Introduction to polyol methodThe mixture stirred and refluxed at 160for 60 minSeparation by centrifugation, PurificationAg nanowiresYugang Sun, et al. Adv. Mater.,2002,14,833-8363.2 MechanismI: ReductionII: Nucleation of seeds III: Heterogeneous nucleation and Crystal gr

6、owthYugang Sun, et al. Nano Lett.,2003,3(7):955-959EGServe as both reducing agent and solvent I: ReductionCH2OHCH2OH CH3CHO+H2O2Ag+ +CH3CHO 2Ag0+CH3COCOCH3+2H+3.2 Mechanism (Cont.)I: ReductionII: Nucleation of seeds III: Heterogeneous nucleation and Crystal growthII: Nucleation of seeds MTPs (multip

7、ly twinned particles 多重孿晶多重孿晶)3.2 Mechanism (Cont.)I: ReductionII: Nucleation of seeds III: Heterogeneous nucleation and Crystal growthPeng Jiang, et al.Chem.Eur.J.,2004,10,4817-4821PVPServe as both capping agent and inducing agent3.2 Mechanism (Cont.)Chang Chen, et al.Nanotechnology,2006,17:466-474

8、3.3 ImprovementsSeveral key factorsFormation of MTPs :Requiring a low concentration of AgNO3Etching of MTPs:Requiring reducing the effct of oxygen on the activity of MTPsImprovements:Less etching of MTPs, Less reaction time, Increasing concentration of AgNO3 for mass production3.3.1 Improved polyol

9、method (I)-CuCl-or CuCl2-mediated polyol processWhat is the role of Cl-?Ag+Cl-AgCl, reducing the concentration of free Ag+, What the role of Cu+ or Cu2+? Cu2+EGCu+, Cu+OCu2+,Scavenging the absorbed atomic oxygen from the silver seedsWhat are the advantages?All the reagents can be delivered using pip

10、ettes into disposable glass vialsBy scavenging the oxygen, Ag nanowires with larger aspect ratios were grown preferentially ,leading to a high-yield production.Kylee E.Korte, et al. J.Mater.Chem.,2008,18:437-4413.3.2Improved polyol method(II)-microwave-assisted polyol methodWhat are the roles of mic

11、rowave ?Serving as the heat source;Leading to conducting eletrons polarized and superheating, accelerating Ag0 deposition especially on the end of nanowires;Reducing the etching effect of oxygen;What are the advantages?Less reaction time (within 30min);High yield,High purity(95% after isolation);Con

12、ducted under ambient O2 conditons ;Linfeng Gou, et al. Chem. Mater.,2007,19,1755-17602AgNO3 +CH3CHO 2Ag0+CH3COCOCH3+2HNO33.3.3 Improved polyol method (III)-steel-assited polyol methodProblem:High concentration of AgNO3 is not faverable for Ag nanowires growthSolution: adding steel (Si=1.05%,Mn=1.05%

13、,Cr=17.47%,Ni=7.18%,Fe=73.25%)Weijia Zhang, et al. Chem. Mater.,2008,20,1699-1704What are the advantages?Ag nanowires with high aspect ratio can be formated even at a AgNO3 concentration of 0.5M , Mass production of Ag nanowiresless additional influence due to rare replacement between Ag and FeBeing

14、 conducted under ambient O2 conditons because of less etching effect compared with that of HNO3, The diameters of nanowires can be adjusted by changing the initial concentration of AgNO3. Weijia Zhang, et al. Chem. Mater.,2008,20,1699-17043.3.3 Improved polyol method (III)-steel-assited polyol metho

15、d (cont.)3.4 Further research on silver nanowiresrequiring more reaserch on the applications and properties of silver nanowiresSelf-assembly into silver rafts Y.Gao, et al. Chemical Physical Letters,2003,380,146-149Jose Luis Elechiguerra, et al. Chem.Mater.2005,17,6042-6052Corrosion References1.Jie

16、Yao, et al.Science,2008,321,9302.Yugang Sun, Younan Xia. Adv. Mater., 2002,14:833-8363.Yugang Sun, Brain Mayers , et al. Nano Lett., 2003,3(7):955-9594.Chang Chen, Li Wang , et al. Nanotechnology,2006,17:466-4745.Kylee E.Korte, Sara E.Skrabalak, et al. J.Mater.Chem.,2008,18:437-4416.Linfeng Gou, Mircea Chipara, et al. Chem. Mater.,2007,19:1755-17607.Weijia Zha