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Analysis And Characterization Of Several Nanomaterials Synthesized By Electrochemical And Liquid Method

Posted on:2012-03-31Degree:DoctorType:Dissertation
Country:ChinaCandidate:X Z ShiFull Text:PDF
GTID:1101330335966572Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
Synthesis of nanomaterials with controlled structure and morphology has been pursued with great effort recently, driven by both the excitement of understanding new chemistry and the potential hope for practical applications. In this paper, electrochemical and organic phase synthesis method were used to fabricate several nanofilms and nanoparticles, and many instruments, including SEM, TEM, HR-TEM, UV/Vis, SERS were employed to characterize the as-synthesised nanomaterials:1) Electrochemical atomic layer deposition (EC-ALD) technique was employed to fabricate the first layer of Sb2Se3 compound on gold substrate. Cyclic votammgyclic and chronoamperometric method were used to investigate the formation mechanism of first layer of Sb2Se3 formed on gold electrode through EC-ALD method. The deposition and stripping of antimony on Se-modified gold electrode proceed by a two-dimensional nucleation and growth mechanism in the underpotential region. Additionally, Sb2Se3 was also fabricated on ITO substrate through electrochemical method and the growth kinetics was investigated according to current density-time data. The morphology, crystalline structure and element component was also studied.2) Monodisperse silver nanoparticles with narrow size distribution are synthesized by direct reaction of the silver acetate and oleylamine in Benzyl ether. The particle sizes are controlled by tuning the precursor concentration and the ratio between precursor and surfactants. Surface plasmon resonance (SPR) phenomena and surface enhanced Raman scattering (SERS) observed from the silver nanoparticles are found to be size-dependent. As the particle size increases, the SPR peak red shifts and the SERS signal intensities increases.3) Monodisperse silver nanocubes were synthesized by the reduction of silver acetate in hydrophobic solvent benzyl ether. Cetyltrimethylammonium bromide (CTAB) was used as surfactants in the synthesis process. Transmission electron microscopy (TEM), high resolution TEM and X-ray diffraction (XRD) was used to investigate the morphology, crystalline structure and surface adsotption chemistry of the silver nanocube. The factors for the formation of silver nanocube were investigated systematically and we found that the Br- played critical role in the formation of silver nanocube. The silver nanocubes show good surface Plasmon resonance and surface enhanced Raman scattering properties, which have promising applications in biosensor, SERS, and biomedicine.4) AuPd bimetal nanoparticles ware successfully synthesized at low themperature. In the synthesis, oleylamine was used as reductant and also solvent. X-Ray dispesion was used to study the crystalline structure of the bimetal nanoparticles and show that alloy was formed in the AuPd nano particles. UV/Vis and X-ray photoelectronic were used to investgated the SPR properties and surface adsorption chemistry. The SERS properties of the two bimetal nanoparticles was studied using 4-mercaptobenzoic acid molecule as model molecules and the results show that the two bimetal nanoparticles could served as effective SERS substrates.5) Gold nanorods with aspect ratios from 1 (particles) to 31.6 were synthesized by the seed-mediated method and packed in a highly ordered structure in a large scale on silicon substrates through capillary force induced self-assemble behavior during solvent evaporation. The gold nanorod surface exhibits strong enhancement effect to Raman scattering spectroscopy. By changing the aspect ratio of Au nanorods, it was found that the enhancement factors decrease with the increase of aspect ratios. The observed Raman scattering enhancement is strong and it should be ascribed to the surface plasmon coupling between closely packed nanorods, which may result in huge local electromagnetic field enhancements in these confined junctions.
Keywords/Search Tags:electrochemical, liquid synthesis, nanocrystal, surface plasmon resonance, surface enhanced Raman scattering
PDF Full Text Request
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