离子交换膜中CdS单分散纳米晶的合成及其光学性质

以硫代乙酰胺(TAA)为前驱体, 采用液相反应在全氟磺酸离子交换膜(Nafion)中自组装得到了均匀分布、单分散的纳米CdS晶体；与文献报道的前驱体如Na₂S和H₂S不同, TAA可以在全氟磺酸离子膜中均匀扩散, 最终在Nafion薄膜中得到均匀分布的纳米CdS晶体. 利用高分辨电子显微镜(HRTEM)、X射线衍射仪(XRD)和能量散射X射线分析(EDXA)研究了Nafion薄膜模板中CdS纳米晶体的形成机理、晶粒大小和分布；采用紫外- 可见吸收光谱和荧光光谱分析了Nafion薄膜中单分散纳米CdS晶体的光学性质. 结果表明, 随CdS纳米晶体尺寸的减小, 量子尺寸效应明显增强；在紫外吸收谱中表现为吸收边明显蓝移, 而在光致发光谱中, 表现为带边发射的蓝移.

Preparation and Optical Properties of Nanocrystalline Cadmium Sulfide in Perfluorinated Ionomer Membrane

Using thioacetamide (TAA) as precursor, homogeneous and steady monodispersed CdS nanocrystals were synthesised in Perfluorinated Ionomer Membranes (Nafion) by self-assembly. Unlike the ionic precursors such as Na2S and H2S, TAA could diffuse into the cationic-exchangeable ionomer membranes much more uniformly, Which led to the homogeneous distribution of CdS nanoparticles in the Nafion membranes. High resolution transmission electron microscopy(HRTEM), X-ray diffraction(XRD) and energy dispersive X-ray analysis(EDXA) were used to investigate the synthesis mechanism, the size distribution and the microstructure of these CdS nanoparticles embedded in Nafion membranes. Optical properties of CdS nanoparticles in Nafion were also characterized by UV-Vis absorption and luminescence spectra. The results show that the quantum size effect becomes strong with the decrease of the size of CdS nanocrystals. Blue shift appears both on the absorb edges in the absorption spectra and on the band-edge emission in the luminescence spectrum.