基于ZnS纳米粒子的有机凝胶荧光薄膜的制备及其传感性能

本文首先采用油水界面法制备发光纳米ZnS粒子,再通过物理混合法,将其分散在溶有小分子胶凝剂的有机溶液中,流延于玻璃基质表面,得到ZnS荧光薄膜。实验结果表明,ZnS纳米粒子的平均粒径大小约为200 nm,具有立方晶型结构,并且在杂化薄膜中具有良好的分散性;胶凝剂形成的网络结构对ZnS纳米粒子具有良好的限域效应,表现为稳定的发光性能;气敏实验表明,该杂化膜对挥发性有机单胺和二胺具有灵敏的选择性传感作用;且其灵敏度随着杂化薄膜中ZnS担载量的增大逐渐提高;可逆性实验表明该薄膜对乙二胺蒸汽具有良好的可逆响应性。

Preparation and Sensing Properties of Organic Gel Fluorescence Films Based on ZnS Nanoparticles

Accurate and rapid detection of organic amines in the vapor phase is essential for various applications such as agricultural use, industrial and environmental testing, and food security. Supramolecular gels composed of cholesterol derivative-based low-molecular-mass gelators (LMMGs) have attracted considerable attention owing to their unique character and formation mechanisms. In this study, a ZnS-supramolecular organogel hybrid film for amine vapor sensors was reported. It must be pointed out that the method of preparation of hybrid films considered here is different from that of the ZnS-organogel hybrid films previously reported. Because the sensing performance of nanomaterials strongly depends on their nanostructures, it is expected that nanomaterials synthesized by different methods exhibit different nanostructures and ultimately different sensing properties. The luminescent ZnS nanoparticles were first prepared by the oil-water interface method, before being dispersed in an organic solution containing the LMMG. Finally, the aforementioned solution was casted onto the surface of a glass substrate to fabricate a ZnS-supramolecular organogel fluorescent hybrid film after drying at room temperature. Scanning electron microscopy observations revealed that the surface morphology of the hybrid film was uniform cross-linked nanofibers. Transmission electron microscopy results revealed that the average particle size of the obtained ZnS nanoparticles is about 200 nm. The crystal structure of the ZnS nanoparticles is cubic, as revealed by X-ray diffraction. The photoluminescence emission spectra of the ZnS-supramolecular organogel film were recorded for various quantities of ZnS loading; the maximum emission wavelength of the hybrid films hardly changed, indicating that the dispersity of the ZnS nanoparticles in the hybrids is very well. Because the film network formed by the gelator has a good confinement effect on the ZnS nanoparticles, the hybrid film exhibits stable luminescence performance. Sensing experiments showed that the hybrid films are sensitive to the existence of organic monoamine and diamine vapors, and the sensitivity improved as the dosage of ZnS nanoparticles was increased. The quenching mechanism was discussed by comparing the fluorescence lifetimes of the hybrid films in the presence of air and ethylenediamine (EDA) vapor. It was found that the sensing mechanism is mainly static quenching, with a very small amount of dynamic quenching. The sensing performances of the film for common volatile organic compounds were investigated with a detection limit of 10.13 ppm (1 ppm = 1 × 10^-6, volume fraction) obtained for the EDA vapor. Reversible experiments indicated that the films have a good reversible response in the presence of EDA vapor. It is anticipated that this type of supramolecular organogel hybrid film could find applications in the monitoring of volatile organic amines in the areas of industry and environment.