| "Nanomaterils" refers to materials with morphological features on the nanoscale, and especially those which have special properties stemming from their nanoscale dimensions. As the sizes of the materials are close to light wavelength and with high surface areas, a certain number of physical properties of the nanomaterials alter with the change from macroscopic systems, for examples, melting point, magnetic property, optical property, thermal and electron conduction. Carbon nanomaterials possess quite uinique physical-chemical property and multiple forms, have been wildly used in areas such as biology, semiconduction, information and communication technology, medical and health. However, the synthesis of carbon nanaomaterials (laser etching, plama irradiation, CVD...) usually needs harsh condition, expensive equipments and consuming high energy. This thesis discussed simple synthesis of luminescent carbon nanoparticles from natural gas soot and further synthesized carbon/metal nanocompostie as catalysts for oxygen reduction reaction.1. Carbon nanoparticles were prepared by refluxing the combustion soot of natural gas in nitric acid. Transmission Electron Microscopy measurements showed that the resulting particles exhibited an average diameter of 4.8±0.6 nm, and the crystalline lattices were consistent with graphitic carbons.13CNMRand FTIR spectroscopic measurements further confirmed the presence of sp2 carbons in the form of aryl and carboxylic/carbonyl moieties. The resulting carbon nanoparticles were found to emit photoluminescence with a quantum yield of approximately 0.43%. Additionally, the emission band energy of the carbon nanoparticle was very similar to that of much smaller carbon nanoparticles obtained from candle soot, suggesting that the photoluminescence might arise from particle surface states, analogous to the behaviors of semiconductor quantum dots with an indirect bandgap. In electrochemical measurements, two pairs of well-defined voltammetric waves were observed, which might be ascribed to the peripheral functional moieties that were analogous to phenanthrenequinone derivatives. Interestingly, the carbon nanoparticles might also be exploited as nanoscale structural scaffolds for the deposition of nanostructures of varied transition metals, leading to the formation of metal-carbon functional nanocomposites.2. Luminescent carbon nanoparticles were prepared from natural gas soot. The photoluminescence was found to be enhanced by more than 10 folds when the particles were subject to hydrothermal treatment between 200 and 340℃for varied periods of time (up to 15 hours). This was accounted for by the effective removal of quinone moieties from the particle surface. Consistent results were observed in UV-vis, NMR, and electrochemical measurements. The correlation may be exploited for controlled manipulation of nanoparticle optoelectronic properties.3. A simple method was used to prepare a series of Pt nanoparticles deposited on a nano-size carbon substrates, and the size of the platinum complex can be controlled by just easily change the feeding ratio between carbon and platinum. These carbon nanoparticles possessed large surface areas because of their small size, which is a necessary to be efficient for a solid catalyst. Because of the chemical inertia, carbon is supposed to be a zero pollutant. Pt catalysts supported on carbon confine the contamination to the environment only in the Pt metal adopted. The electrocatalvtical activities of the as synthesized particles for ORR were examined and compared by cyclic and rotating disc voltammetry. Since the similarity of the particle constituents, it will be a favorable system to study core size effects on the catalysis activity.4. A hollow core waveguide with silver nanoparticles coated on the inner wall has been used for molecular detection based on surface enhanced Raman scattering (SERS). With rhodamine 6G as an analyte molecule and two types of silver nanoparticles as double SERS substrates, the inner wall coated hollow core waveguide (IWCHCW) exhibits higher sensitivity than previous sampling methods with only one substrate The improvement of sensitivity is attributed to the additional enhancement of the electromagnetic field by double substrate "sandwich" structure. The simple architecture and high sensitivity of IWCHCW make it promising for molecular detection in various analytical and sensing applications.5. Surfaces of water-soluble CdS quantum dots were modified by polyethyleneimine (PEI). The modification highly enhanced luminescent property of quantum dots, the obtained structure was used as sensor for detecting Cu2+...
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