Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials

Precious metals (Au, Ag, Pd) nanoparticles for sensing and visualization of Electroanalytical Chemistry Research

Author LiSiNi
Tutor ZhuNingNing
School Shanghai Normal University
Course Analytical Chemistry
Keywords gold nanoparticles silver、palladium nanoparticles Cr3+ nitrite tryptopha
CLC TB383.1
Type Master's thesis
Year 2011
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Chemically functionalized gold nanoparticles (AuNPs) exhibit distance-dependent optical properties, making them useful in colorimetric detection systems, especially for detection of heavy metal ions.To ensure the sensitivity and selectivity of the detection, the ligands on the particle surface should have strong affinity and high specificity to the metal ions.Si(?)er, palladium nanoparticles also have good electrocatalytic activity. Carbon. nanotubes has particular machanical, chemical and electrical properties. It can encourage electron transfer when carbon nanotubes are modified on electron surface.So carbon nanotubes in materials, medicine, physics, chemistry and other fields has great potential.In this paper, Cr3+was visual determined by using the characteristics of gold nanoparticles, and silver and palladium nanoparticles and carbon nanotube modified glassy carbon was further studied.I. Selective Detection of Trace Cr3+in Aqueous Solution by Using citrate capped Au nanoparticleThe development of highly sensitive and selective analytical methodology for the detection of trace levels of chromium species is of significant interest. Several methods for Cr3+have been reported recently, but they require using organic solvents and generally have a relatively high detection limit. Herein, we report a simply prepared gold nanoparticle-based sensor for detecting Cr3+ over 17 other metal ions including chromium(VI) in aqueous solution. This is because AuNps have interesting optical and electronic properties, for example, the surface plasmon resonance that essentially depends on the size, shape, and distance between the NPs, Au NPs have been widely used in various research and industrial fields. The functionalized gold nanoparticles became aggregated in solution in the presence of Cr3+ by an ion-templated chelation process, which caused an easily measurable change in the extinction spectrum of the particles and provided an inherently sensitive method for Cr3+ detection in aqueous solution.II. Determination of nitrite based on AgNPs-modified MWNTs for electro-catalytic oxidation of nitriteThis study describes a simple and reliable method for the electrochemical determination of nitrite based on AgNPs modified carbon nanotubes. Chronoa-mperometry was used to deposit AgNPs onto multi-walled carbon nanotubes (MWNTs)-modified glass carbon (GC) electrodes (written as AgNPs/MWNT-modified GC) and which were used for the electrochemical determination of nitrite. The studies show that the AgNPs/MWNTs-modified electrodes demonstrated significantly enhanced electrochemical activity towards nitrite oxidation. Chronoamperometry studies reveal that the amperometric response is rapid, stable, and offers a linear dependence over a wide range of nitrite concentrations from 71.3μmol/L to 1550μmol/L. The electrochemical properties of the AgNPs/MWNTs nanocomposites are reasonably envisaged to be promising for providing a nanostructured platform in the development of electrochemical sensors or biosensors.Ⅲ.Palladium nanoparticle/carbon nanotube hybrids as an enhanced material for sensitive amperometric determination of tryptophanIn this work, a highly sensitive electrochemical sensor for the determination of tryptophan (Trp) was fabricate by electrodeposition of palladium (Pd) nanoparticles (PdNPs) onto multi-walled carbon nanotube (MWNTs) films precast on a glassy carbon electrode (GCE), forming an PdNP-MWNTs composite-modified GCE (PdNP-MWNTs/GCE). Cyclic voltammetry(CV) was used for the surface analysis of the electrode. The results indicate that the hybrid nanomaterials induced a substantial decrease in the overpotential of the Trp oxidation reaction and exhibited a remarkable synergistic effect on the electrocatalytic activity toward the oxidation of Trp. In phosphate buffer solution (pH 7.4), themodified electrode showed excellent analytical performance for the amperometric determination of Trp. The peak currents possess a linear relationship with the concentration of Trp in the range of 2.5x10-5mol/L to 1.7x10-4mol/L, and the detection limit is 0.4μmol/L (S/N= 3). In addition, the modified electrode was used to determine Trp concentration in pharmaceutical samples with satisfactory results.

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