银纳米线的自组装合成

Three-Phase-Interface SelfAssembly Process
Synthesize uniform, hydrophilic Ag nanowires with a high aspect ratio, which were 80–100nm in diameter and 20–30 mm in length. A sparkling film appeared on the water surface. The film could be transferred to a conveniently hydrophilic substrate, such as a glass or silicon wafer.
NO NO NO YES
(a) AgClO4
(b)AgNO3
B2O72−, NO2− NO3-
NO3-
●sp2 triangular planar
configuration ●a positive charge at N
Anions molecular geometry
Chien Lin Kuo and Kuo Chu Hwang. Langmuir. 2012, 28, 3722−3729
Extension
PVP as a capping agent Uniform diameter of 80 -10 nm Aspect ratio ranging from 500 to 2500 Non-polar solvent: toluene or hexane As(V) detection using AgNW substrates
Conclusion
Properties of Ag nanowire
1、Transparent conductive electrode （a promising substitute of ITO films） 2、As a substrate for Surface enhanced Raman scattering 3、Unique template for novel nanostructures and functional nanomaterials （Yugang Sun,Nanoscale, 2010, 2, 1626–1642）
The LOD of As(V) in water was estimated to be 5 ppb or lower
J. Mater. Chem. A, 2013, 1, 13496–13501
Conclusion
ⅠPoly process: NO3-— the growth of long Ag NWs PVP — lateral confinement of nanowire CO32-/NH4+—deposition and dissolution at the curved ends Different ratios make big changes
Templateless (avoid the step of template removal) : The products of these
templateless methods were, however, often characterized by problems such as relatively low yields, irregular morphologies, polycrystallinity, and low aspect ratios.
Approaches for the Production of Ag Nanowires
“hard” templates:These templates were effective in fabricating nanowires
with uniform and controllable dimensions, many of them needed to be selectively dissolved under harsh conditions in order to harvest the nanowires.
ⅡThree-Phase-Interface Self-Assembly :
Uniform and ordered Ag NWs film with a high aspect ratio
Diameter: 30-40nm Lengths: ～50μm
With FCC phase
Yugang Sun,Yadong Yin,Brian T, Mayers,Thurston Herricks, Younan Xia. Chem. Mater. 2002, 14, 4736-4745
Nitrate Ion ——Growth Mechanism for Ag nanowires
Lateral confinement of PVP molecules Dynamic reversible deposition and dissolution of silver atoms at the curved ends
Shaohong Liu ,et.al, CrystEngComm，2014,16, 244-251
Adv. Funct.Mater., 2010, 20, 958–964.
Mechanism
Influencing Factors
Absence of PVP Species of organic solvent

SEM images of the films of Ag nanowires and corresponding optical photographs prepared using CH2Cl2(a–b), CHCl3(c–d), and CCl4(e–f ).
Polyol Processes
Xia and co-workers synthesized silver nanowires in high yields by reducing AgNO3 with EG heated to 148 ℃in the presence of PVP and a trace amount of NaCl, CuCl2 or CuCl. Its side surfaces are tightly passivated by PVP while its ends remain reactive toward the arriving silver atoms.
“soft” templates: The silver nanowires synthesized using these templates
were often in the form of aggregated bundles, and the templates also needed to be removed in order to recover the individual nanowires.
Polyol Processes
The additives, such as CO32− and NH3, resulting from the dissociation of (NH4)2CO3, have the ability to accelerate the oxidative dissolution of silver.
Polyol Processes
1000
Self-assemble Ag Nanowires by Polyol Process
Schematic Illustration of The Process
Main Chemicals and Their Roles EG: solvents and reductants (Ethylene glycol) Pt Seeds : nuclei for the epitaxial growth of silver. PVP: polymeric surfactants. AgNO3: Ag sources, while nitrates are uncertain. Results of TEM image and XRD patterns
Other anions, such as ClO4−, B2O72−, NO2−,CO32−, HPO42−, SO42-, only Ag nanoparticles were formed. anions
CO3 2− ClO4−, HPO42−, SO42-
sp2
YES NO NO YES
Central ‘+’ charge
The Self-Assemble Synthesis of Ag Nanowires
蒋莉 谷穗 易娜 程若霖 宛刚 邓健 陆翔 张云龙
Content
Introduction Self-assemble Ag Nanowires by Polyol Process
Three-Phase-Interface Self-Assembly Process