原位表面修饰纳米CdS粒子的表面结构和光学性能

Surface structure characterization and optical properties of surface modified nano-sized CdS particles in solvents

采用微乳液法合成了纳米尺度硫化镉粒子,并用硫醇和咪唑对粒子进行了原位表面修饰.对纳米硫化镉粒子的形貌与表面结构进行了表征,证实了表面修饰剂与粒子间的键合.电镜观察和紫外-可见吸收光谱的测定发现,表面修饰明显地提高了纳米粒子在溶剂中的分散性,改变了纳米粒子的表面结构,消除了粒子表面导致无辐射弛豫的缺陷,因而提高了纳米粒子分散于溶剂体系的荧光性能.修饰剂与溶剂间的相互作用决定了表面修饰粒子在溶剂中的分散性,对纳米粒子的光学性能也有一定的影响.

Nano-sized CdS particles with a diameter of about 6 nm and a relatively narrow size distribution were synthesized in inverse micellar solution. In-situ chemical modification of the surface of these particles was carried out by imidazole and thiol molecules, respectively. The morphologies of the particles dispersed in various solvents were analyzed by TEM observation. FTIR and XPS measurements proved the chemical bonding between the particles and the surface modifiers. UV-Vis absorption and fluorescence emission spectra of CdS suspension in solvents revealed that the surface modification had blocking effects on the surface defects that caused radiationless recombination of charge carriers. The solubility of these re-dispersible nano-powders in different solvents was studied as a function of surface modifier species, modifier dosage as well as solvent effects. The preliminary conclusion is that thiol is more appropriate than imidazole to produce uniform polymer nanocomposites.