低温水相合成巯基化聚乙烯醇/CdS量子点纳米复合物及用于测定环境水样中痕量Cu~(2+)

采用水相合成法,在低温N2气保护条件下,以巯基化聚乙烯醇(PVA)为基体材料合成一种环境友好型PVA/CdS量子点纳米复合物,并通过红外光谱(IR)、X射线粉末衍射(XRD)、透射电子显微镜(TEM)、热重(TG)、荧光光谱(PL)和紫外可见光谱(UV-Vis)等技术手段对复合物进行结构表征和光学性能研究。测试结果表明,复合物中CdS量子点为立方晶型结构,形状为球形,粒径小于5nm,具有很好的稳定性、分散性及发光性质。此外,Cu~(2+)对PVA/CdS水溶液荧光具有良好的猝灭作用,其荧光猝灭程度与Cu~(2+)浓度在1~1000nmol/L范围内呈良好的线性关系,线性相关系数为0.9923,方法检出限为0.12nmol/L。该纳米复合物荧光分析方法简便快速、灵敏度高、检出限低,已应用于实际黄河水样中痕量Cu~(2+)的分析与检测。

Aqueous Synthesis of Thiol-functionalized Polyvinylalcohol/CdS Quantum Dots Nanocomposite at Low Temperature for Detection of Trace Cu2+ in Water

A high quality PVA/CdS QDs nanocomposites modified by thiol-functionalized polyvinylalcohol(PVA) was prepared by aqueous synthetic approaches at low temperature. The samples were characterized by infrared spectroscopy(IR), X-ray diffraction(XRD), transmission electron microscopy(TEM), thermogravimetric analysis(TG), photoluminescence spectroscopy(PL) and ultraviolet-visible spectroscopy(UV-Vis). The results show that CdS QDs in the nanocomposites are spherical particles with a cubic crystal structure and a diameter size of about 5 nm. PVA/CdS nanocomposites have good stability, high dispersibility and excellent luminescence properties. Meanwhile, the fluorescent responses of as-prepared PVA/CdS to different metal ions were studied. Based on the fluorescence quenching behavior of PVA/CdS quantum dots, we established a method for the fluorescent detection of Cu²⁺. When the concentration of Cu²⁺ is in the range of 1~1000 nmol/L, the fluorescence intensity linearly decreases with the increase of Cu²⁺ concentration. The linear correlation coefficient is 0.9923 and the detection limit reaches 0.12 nmol/L. The method provides high sensitivity, simplicity of operation and low detection limit, and is successfully applied to the determination of trace copper in the Yellow River samples.