查看完整版本: 研究人员发现从纳米粒子到纳米孔结构的方法

研究人员发现从纳米粒子到纳米孔结构的方法

[b][size=3]Researchers form metal nanoparticles into porous structures[/size]G;\e$?4ss
[color=Blue]【纳米科技世界论坛快讯】For 5,000 years or so, the only way to shape metal has been to "heat and beat." Even in modern nanotechnology, working with metals involves carving with electron beams or etching with acid.[/color] [/b]@ f\!m~o!a9E

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])t o l[\AdI)s [color=DimGray]Computer simulation, left, shows how platinum nanoparticles will fuse into a structure with tiny pores after the polymers that guide them into position are removed. Right, electron microscope photo of the actual structure.[/color]
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Now, Cornell researchers have developed a method to self-assemble metals into complex nanostructures. Applications include making more efficient and cheaper catalysts for fuel cells and industrial processes and creating microstructured surfaces to make new types of conductors that would carry more information across microchips than conventional wires do.
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The method involves coating metal nanoparticles -- about 2 nanometers (nm) in diameter -- with an organic material known as a ligand that allows the particles to be dissolved in a liquid, then mixed with a block co-polymer (a material made up of two different chemicals whose molecules link together to solidify in a predictable pattern). When the polymer and ligand are removed, the metal particles fuse into a solid metal structure.6H5fe
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'x;`o.v?3p_V "The polymer community has tried to do this for 20 years," said Ulrich Wiesner, Cornell professor of materials science and engineering, who, with colleagues, reports on the new method in the June 27 issue of the journal Science. "But metals have a tendency to cluster into uncontrolled structures. The new thing we have added is the ligand, which creates high solubility in an organic solvent and allows the particles to flow even at high density." 7v:N*MQ&STz
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Another key factor, he added, is to make the layer of ligand surrounding each particle relatively thin, so that the volume of metal in the final structure is large enough to hold its shape when the organic materials are removed.
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0F%l(E%N-aB [ "This is exciting," Wiesner said. "It opens a completely novel playground because no one has been able to structure metals in bulk ways. In principle, if you can do it with one metal you can do it with mixtures of metals."
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Wiesner and two Cornell colleagues, Francis DiSalvo, the J.A. Newman Professor of Chemistry and Chemical Biology, and Sol Gruner, the John L. Wetherill Professor of Physics, as well as other researchers, report in Science how they used the new method to create a platinum structure with uniform hexagonal pores on the order of 10 nm across (a nanometer is the width of three silicon atoms). Platinum is, so far, the best available catalyst for fuel cells, and a porous structure allows fuel to flow through and react over a larger surface area.
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(n-L/A&n1fb The researchers began by mixing a solution of ligand-coated platinum nanoparticles with a block co-polymer. The solution of nanoparticles combines with just one of the two polymers. The two polymers assemble into a structure that alternates between small regions of one and the other, in this case producing clusters of metal nanoparticles suspended in one polymer and arranged around the outside of hexagonal shapes of the other polymer. Many other patterns are possible, depending on the choice of polymers.
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"VR$U ?"I s)@+yu The material is then annealed in the absence of air, turning the polymers into a carbon scaffold that continues to support the shape into which the metal particles have been formed. Wiesner and colleagues have previously used the carbon scaffold approach to create porous nanostructures of metal oxides.k]G'v'V? y;D
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The final step is to heat the material to a higher temperature in air to oxidize the ligands and burn away the carbon. Metal nanoparticles have a very low melting point at their surface, so the particles sinter together into a solid metal structure. The researchers have made fairly large chunks of porous platinum this way, up to at least a half-centimeter across.n }-o n"_&S,V

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H~ In addition to making porous materials, the researchers said, the technique could be used to create finely structured surfaces, the key to the new field of plasmonics, in which waves of electrons move across the surface of a conductor with the information-carrying capacity of fiber optics, but in spaces small enough to fit on a chip.
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Source: Cornell University

希望得到后续进展以及相关文献。

[url]http://www.news.cornell.edu/stories/June08/nanoporous.ws.html[/url]Nuy:R;q1V m9Ytt
[url]http://www.pcb007.com/anm/templates/article.aspx?articleid=21844&zoneid=145&v=design[/url][8b|
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[url]http://www.sciencemag.org/cgi/content/abstract/320/5884/1748[/url]

`l _#T:r ^;a"j? Science 27 June 2008:
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p Vol. 320. no. 5884, pp. 1748 - 1752
GU'[tt!SP DOI: 10.1126/science.1159950
-oH;nv b'l6p:R Prev | Table of Contents | Next  
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}:E9?B'K&t9eUo7L Reports
-@ zYk*I(KVI Ordered Mesoporous Materials from Metal Nanoparticle–Block Copolymer Self-Assembly
N-gX4L t?:rz Scott C. Warren,1,2 Lauren C. Messina,2 Liane S. Slaughter,2 Marleen Kamperman,1 Qin Zhou,2 Sol M. Gruner,3 Francis J. DiSalvo,2 Ulrich Wiesner1*
G$x~ s;n-R\2Q)? The synthesis of ordered mesoporous metal composites and ordered mesoporous metals is a challenge because metals have high surface energies that favor low surface areas. We present results from the self-assembly of block copolymers with ligand-stabilized platinum nanoparticles, leading to lamellar CCM-Pt-4 and inverse hexagonal (CCM-Pt-6) hybrid mesostructures with high nanoparticle loadings. Pyrolysis of the CCM-Pt-6 hybrid produces an ordered mesoporous platinum-carbon nanocomposite with open and large pores (10 nanometers). Removal of the carbon leads to ordered porous platinum mesostructures. The platinum-carbon nanocomposite has very high electrical conductivity (400 siemens per centimeter) for an ordered mesoporous material fabricated from block copolymer self-assembly.
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1 Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.
+~4gz1u3u 2 Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
;J1F4Rd| 3 Department of Physics, Cornell University, Ithaca, NY 14853, USA.
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+`8k|eB;X'u&xUr4Tto * To whom correspondence should be addressed. E-mail: [email]ubw1@cornell.edu[/email] D/G"zB$Da~&rz/zV;R
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请某人上传此文章和supportinginformation  讨论一下，看来这个工作不错。

supporting information可以免费下载，三十多页。工作好是好，但是看上去对合成的要求过高。配体和嵌段共聚物都是自己合成的，很多还需要无水无氧环境，加入试剂的时机。

有没有更简单的方法？和和J!G.WO4XL,MZ
supporting information看过了，合成看起来是很麻烦的

:handshake :handshake :lol

下载连接Wj LC^R7i ]N
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谢谢7楼的:handshake
k"gi`f2n.m"f+A 支持信息如下： ^,VMkc7{;QV
[url]http://www.brsbox.com/filebox/down/fc/b8a27f8be244bb6aa325871e9483f5f4[/url]
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我觉得工作非常有意义，有机合成还可以，不算难。这对于金属纳米粒子的合成非常有意义。也许这种多孔金属的热稳定性不够好，但对于低温的催化反应意义影响非常的大！下一步的工作可能有两点：一是方法的改进，一是找到实际应用的模型研究。
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[[i] 本帖最后由 赵桐田 于 2008-08-21 15:29 编辑 [/i]]

学习:handshake

学习一下:handshake

希望得到后续进展以及相关文献。

:handshake :handshake :handshake :victory: :victory:

学习一下:victory: :victory:

谢谢:handshake :victory: :lol

估计不好合成！:handshake

学习了！:victory:

学习一下:lol :lol

看看这个文献！！！！

回复 7# 的帖子

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学习一下  或许可以采用更简单的方法来实现