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文档下载 免费文档下载 http://doc.xuehai.net/ 3 金属材料合成 3-2 B 本文档下载自文档下载网,内容可能不完整,您可以复制以下网址继续阅读或下载: http://doc.xuehai.net/beab61e9ba638eb80bc6829b3.html 陶瓷工艺 Examples of metal particles from chemical reduction in aqueous solutions CTAB = cetyltrimethylammoniumbromide (C16H31)(CH3)3NBrSDS = sodium dodecylsulfate CH3(CH2)11OSO3Na Templatingmethod (A4) 纳纳 Dendrimer-TemplatedNanoclusterSynthesis 聚酰胺胺 Structure of poly(amidoamine) dendrimer (PAMAM) Generation 2 PAMAM Dendrimer 文档下载 免费文档下载 http://doc.xuehai.net/ Sacrificial hydrogen protective strategy for the nanoparticles with a Pd shell-Pt core structure. Y. Wang, N. Toshima, J. Phys. Chem. B, 1997, 101, 5301. Synthesis of FePtalloy nanoparticle Mechanism: Chemistry versusArt PtCl2 2OH)2 Pt seeds PVP ?AgNO3PVPGrowth(CH Various Stages of Wire Growth 10 min 40 min20 min60 min Silver Nanowireswith φ ~40 nm Ex.) Au nanorodssynthesized by seed-mediated preparation ofbimetallic 文档下载 免费文档下载 http://doc.xuehai.net/ chemical reduction://doc.xuehai.net/beab61e9ba638eb80bc6829b3.htmlr chemical reduction Planar density of atoms of FCC structure 111: 0.907 100: 0.785 110: 0.555 “ Zipping model”:the formation of the bilayerof CnTAB(squiggles) on the nanorod(black rectangle) surface may assist nanorodformation as more gold ion (black dots) is introduced. The preferential bindingis based on sterics-the Au atom spacing on the side faces is more comparable to the size of the CTA headgroupthan the close-packed 111 face of gold, which is at the ends of the nanorods. (CCH note: Could also be due to energy reason.) chemical reduction Mechanism of surfactant-directed metal nanorodgrowth:The single crystalline seed particles have facets that are differentiallyblocked by surfactant (or an initial halide layer that then electrostaticallyattracts the cationic surfactant). Subsequent addition of metal Synthesis of gold 文档下载 免费文档下载 http://doc.xuehai.net/ nanopartichttp://doc.xuehai.net/beab61e9ba638eb80bc6829b3.htmlles of different shapes z z zGeneral idea is the same as the growth of gold nanorods (seed-mediated method)Slightly change the conditions when growing nanorods (concentration of different reactants)Cubes, hexagon, triangle, tetrapods, branchedExperimental methods involve: 1) the preparation of Au seed particles; and 2) the subsequent addition of an appropriate quantity of the Au seed solution to the aqueous growth solutionscontaining desired quantities of cetyltrimethylammonium bromide (CTAB), HAuCl4, ascorbic acid (AA), and in some cases a small quantity of AgNO3. T. K. Sau, C. J. Murphy, J. Am. Chem. Soc.2004, 126, 8648-8649 Synthesis of gold nanoparticles of different shapes§For triangular profile and cubes, this corresponds to edge lengths; for hexagonal profile, this corresponds to the distance between opposite sides; and for tetrapodsand branched phttp://doc.xuehai.net/beab61e9ba638eb80bc6829b3.htmlarticles, this corresponds to center-to-tip distances. For cubes, triangles and hexagons, the dimensions are averaged over ~120 文档下载 免费文档下载 http://doc.xuehai.net/ particles and are reproducible to within 5% of the given value; for the other shapes, the dimensions are averaged over ~120 particles and are within ~10% of the given value. a)6.0x10-5M AgNO3was used. b)Seed(5) was used here, otherwise results are reported for seed(1). zThe factors [CTAB], [Au], [Au3 ]and [AA] are interdependent. Synthesis of gold nanoparticles of different shapes [AA]Scale bar = 100 nm increases from A to C and seed concentrationincreases from C to D. Synthesis of gold nanoparticles of different shapesTEM images showing cubic to rod-shaped gold particles produced with low AA concentrationin the presence of small quantity of AgNO3. [CTAB] was increased from 1.6 x 10-2M (A), to 9.5 x 10-2M (B,C,D). [Au3 ] decreased from (C),http://doc.xuehai.net/beab61e9ba638eb80bc6829b3.html (B) whereas to seed concentration increased from C to D. Scale bar ) 100 nm. Synthesis of gold nanoparticles of different shapesTEM images of branched Au nanoparticles, varying in the dimension and number of branches. prepared under various combinations of [seed]/[Au3 ] ratio, and the concentrations of CTAB and AA. Tetrapods(A), star-shape (B), larger tetra- pods (C), and multi-pods (D and E). 3.2.4 SonochemicalApproaches for NanoscaleParticle Synthesis 文档下载 免费文档下载 http://doc.xuehai.net/ Ultrasonic: > 20kHz Formation of Highly Reactive Radicals Depending on the liquid medium, sonicationleads to the generation of oxidizing and reducing radicals In aqueous solution??H2? M In solutes like alcohols, sonicationleads to secondary radicals ???2(H2O) ?ROH M? M RO H 磁场辅助水热法制备 Ni 纳米粒子 NiCl2·6H2O 酒石酸钠 NaH2PO2·H2 O NaOH 常规条件磁场条件 磁场辅助水热法制备 Ni 纳米粒子://doc.xuehai.net/beab61e9ba638eb80bc6829b3.htmlr NiCl2·6H2O 柠檬酸三钠 NaH2PO2·H2O NaOH 常规条件 磁场条件 文档下载 免费文档下载 http://doc.xuehai.net/ Electrochemical reduction to prepare Au nanorod (TEM micrographs of Au nanorodswith different aspect ratios 2.7 (top) and 6.1 (bottom). Scale bars represent 50 nm. Another important factor controlling the aspect ratioof the Au nanorodsis the presence of a silver plateinside theelectrolytic solution, which is gradually immersed behind thePt electrode. The redoxreaction between gold ions generatedfrom the anode and silver metal leads to the formation of silverions. Wang and co-workers found that the concentrationof silver ions and their release rate determined the 文档下载 免费文档下载 http://doc.xuehai.net/ length ofthe nanorods.The complete mechanism, as well as the roleof the silver ions, is still unknown. 文档下载网是专业的免费文档搜索与下载网站,提供行业资料,考试资料,教 学课件,学术论文,技术资料,研究报告,工作范文,资格考试,word 文档, 专业文献,应用文书,行业论文等文档搜索与文档下载,是您文档写作和查找 参考资料的必备网站。 文档下载 http://doc.wendoc.com/ 亿万文档资料,等你来免费下载