Study On Preparation And Properties Of Semiconductor And Metal Nanomaterials

(1) High-quality CdSe quantum dots were prepared in organic phase, and then were transferred into water phase. The samples obtained were characterized by X-ray Diffraction (XRD), Energy Dispersive X-ray Analysis (EDX), Ultraviolet-visible Spectroscopy (UV-vis), Fluorescence Spectroscopy (FL) and Transmission Electron Microscopy (TEM), which testified that CdSe quantum dots were fabricated. The fluorescence property of the samples was studied from three ways: 1. by alternate-adding, CdS grew up on the surface of CdSe quantum dots, which had stronger fluorescence, and CdSe/CdS composite nanoparticles showed double-fluorescence; 2. by hydrolysis of (C2H5)4SiO4 (TEOS), CdSe@SiO₂ nanoparticles were prepared, different content SiO₂'effect on fluorescence of CdSe quantum dots was exhibited, and SiO₂'effect on the fluorescence stability of CdSe quantum dots was investigated by ultraviolet irradiation, which indicated that, with more SiO₂ on the surface of CdSe quantum dots, fluorescence of the samples reduced, but the fluorescence stability of the samples was improved due to passivation of SiO₂; 3. PAMAM'effect on the fluorescence stability of CdSe quantum dots was investigated by ultraviolet irradiation, which indicated that, PAMAM stabilized CdSe quantum dots efficiently and strengthened their fluorescence.(2) With Se powder as Se source, Pb(Ac)₂·3H₂O as Pb source, oleic acid as the capping ligand, a novel route to prepare PbSe quantum dots in the high boiling point solvent of paraffin liquid was studied. PbSe quantum dots obtained were transferred from organic phase to water phase. Characterized by Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD) and Energy Dispersive X-ray Analysis (EDX), the products'appearance and component were investigated, which demonstrated that high-quality PbSe quantum dots with regular figure and uniform size were fabricated. The mechanism of preparation was discussed. (3) Undoped and Ce⁴⁺ doped TiO₂ thin films were prepared by sol-gel method. The samples were characterized using Scanning Electron Microscopy (SEM), the photocatalytic activity was evaluated by degradation of methylene blue in the aqueous solution. 0.5 wt. % Ce4+ doped TiO₂ thin films calcined at 400℃showed the highest photocatalytic activity.(4) SrTiO₃ photocatalyst and Fe₃O₄/SrTiO₃ composite photocatalyst were prepared by the co-precipitation method (CPT). The samples were characterized by UV-vis diffuse reflectance spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDX). Photocatalytic activity was evaluated in photodegradation of methyl orange. The results indicated that, Fe₃O₄ doping increased visible-light absorption of SrTiO₃ photocatalyst obviously, which enhanced photocatalytic performance of SrTiO₃ photocatalyst; photocatalytic activity of the 10 at. % Fe₃O₄ doped SrTiO₃ photocatalyst was two times than that of pure SrTiO₃ photocatalyst in photodegradation of methyl orange.(5) Pt nanoparticles doped conducting polymer PEDT/PSS films were fabricated via H2 deoxidizing H₂PtCl₆. Ultraviolet-visible Spectroscopy (UV-vis), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX), X-ray Diffraction (XRD), Raman spectroscopy (Raman), Fourier Transform Infrared spectroscopy (FT-IR) were employed to characterize the properties of as-prepared samples, and Pt doping effect on electrical conductivity of the films was evaluated by conventional four-probe technique. The results indicated that, Pt nanoparticles distributed uniformly in PEDT/PSS films; Pt doping improved electrical conduction of PEDT/PSS films efficiently.