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Preparation, Properties and Applications of Noble Metal Nanoparticles

Author: WuZuoZhou
Tutor: PeiMeiShan
School: Jinan University
Course: Polymer Chemistry and Physics
Keywords: Nano To dendrimers gold particles Sunken gold disc The wound like silver nanowires UV-vis SERS
CLC: TB383.1
Type: Master's thesis
Year: 2011
Downloads: 75
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Abstract

Noble metal nanoparticles show unique chemical and physical properties, and has a very wide range of development and application prospects. Precious metal nanomaterials of unique physical and chemical properties are very relevant to their particle size and morphology. Therefore, the preparation method is simple, mild conditions required, easy to operate controllable particle size, morphology, uniformity, rapid, high yield, good monodispersity has been a goal pursued by the various nano materials preparation. This thesis prepared by chemical reduction anisotropic gold, silver nanoparticles, nanomaterials morphology, growth mechanism and physical and chemical properties and applications by means of SEM, TEM, SERS, XRD, UV-vis other testing techniques more systematic study. LCD sodium dodecyl sulfate and water as a template to restore the the chloroauric acid generated gold disc central depression glycine. Experimental results show that the synthesis recessed gold disc key factors: the temperature, the liquid crystal template, and an amino acid. The temperature is too high, too low, is not conducive to gold plate produces a concave shape. Cetyl trimethyl ammonium bromide and polyvinylpyrrolidone was used instead of the amino-acetic acid, the main product was a gold disk. The reaction mechanism may be: the existence of a large amount of oxygen in a liquid crystal system, with the gold atoms oxide etch; growth and etching of the gold disc occur simultaneously, so as to generate a central depression of the gold disk. The experimental results show that the electro-catalytic oxidation of methanol gold disk central depression the effect Bijinnami disk good. First by tetrabutylammonium bromide as a coating agent, gold nanoparticles synthesized multisection dendritic morphologies uniform, each particle has more than 6 M. branching length of approximately 100 ± 30 nm . Not covered, so that part of the gold surface of the core as tetrabutylammonium bromide clad poor ability, which the late gold particle growth occurs mainly in these uncoated surfaces, thereby forming a dendritic structure. Tetrabutylammonium bromide due to the presence of charge repulsion between the gold particle growth late, to prevent dendrite aggregation, thereby promoting the growth of Mycobacterium. The SERS results show that much branched gold nanoparticles have a stronger enhancing effect on the Raman spectra of the mercaptoaniline described multisection the dendritic gold particles can be detected on mercaptoaniline or other sulfhydryl containing analyte. Low temperature (4 ℃) when the main product is a product of the small irregular flake. Cheap melamine as a coating agent for the first time by ascorbic acid aqueous solution of gold chloride branching length of about 150 nm, the branching number greater than 10, the core diameter of about 600 nm, the yield is close to 100% and good dispersion of dendritic gold particles. The study shows that melamine increasing concentration of the product tend to shift to the spherical particles. This multi-branched gold nanoparticles hydrosol has a very broad absorption peak with between 500-850 nm, the reason may be caused by the superposition of the absorption peak the uneven morphology and particle size of the product a. First polyacrylamide as a template, and by changing the concentration of ascorbic acid in the liquid phase, and then to restore the silver nitrate to obtain a wound-shaped silver nanowires and dendritic silver nanostructure. This method has synthesized under mild conditions (room temperature and pressure), high yield, simple operation, low cost. Experimental results show that the polyacrylamide has played a key role in the formation of linear products. Early in the reaction, a large number of newly generated silver core is polyacrylamide chain adsorbed by the amide group in the molecular chain. As the reaction proceeds, small particles gradually grow up, and thus linked, to ultimately generate a wound-shaped silver nanowires. The higher the concentration of the reducing agent is less conducive to the formation of the wound-shaped silver nanowires. Use as a probe molecule to study aminothiophenol winding like silver nanowires and dendritic silver nanostructures surface enhanced Raman scattering (SERS) activity, the results show that the linear silver nanostructures have strong surface-enhanced Raman scattering (SERS) effect.

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