Preparation And Properties Of Quantum Dots-Layered Double Hydroxides Electrochemical Luminescence Materials

Electrochemical luminescence (ECL) is a chemiluminescence (CL) reaction on the electrode surface caused by the electron transfer, which combines both CL and electrochemical technology. Taking the advantages of fast response speed, strong controllability and wide linear range, ECL technology has been widely used in the fields of food safety, pharmaceutical analysis and environmental monitoring. As a new type of luminescence regent, quantum dots have drawn much attention due to their unique optical, electrochemical and ECL properties. However, several key problems of quantum dots (e.g., easy aggregation, relatively weak ECL intensity and poor optical stability) restrict their ECL applications. Therefore, how to immobilize quantum dots into solid-state electrodes toward enhancing the ECL performances remains a challenge.In this dissertation, based on the structural properties of layered double hydroxides (LDHs), we have constructed the LDHs/QDs and 3-AMS-LDHs/QDs (3-AMS:3-aminophthalhydrazide monosodium salt) acid cyclic hydrazide composite films respectively, by the use of intercalation and/or layer-by-layer (LBL) assembly technique. The electrochemical performance and sensing properties of the film modified electrodes were investigated. The main research contents and results are as follows:1. ECL emitters (QDs) were successfully fabricated on ITO electrode via LBL assembly with LDH nanoparticles. The structural and morphological studies show that the film surface is continuous and uniform with orderly and superlattice structure. The electrochemical and ECL behavior of the LDHs/CdTe film modified electrode demonstrates an improved electron transfer and ECL efficiency. The modified electrode exhibits significant and reversible transformation of the emissive intensity in the temperature range 20-80 ℃. Moreover, LDHs/CdTe displays a sensitive response for nitrite with a wide linear range, low limit of detection, good selectivity and repeatability. Therefore, a bi-functionalized QD-based ECL sensor toward both temperature and nitrite is developed, which provides an effective way for the design and construction of multi-functional ECL sensors.2. By using the intercalation and layer-by-layer assembly method, we firstly prepared the 3-AMS-LDHs composite material, which was then assembled with quantum dots by LBL method. Benefiting from the two-dimensional confined space of LDHs, the distance between adjacent 3-AMS and quantum dots was shortened enough to give ECL resonance energy transfer (E-RET) at the LDHs interface. The (3-AMS-LDHs/CdTe QDs)n films present a long-range ordered stacking in the normal direction of the substrate, and show two characteristic bands in ECL emission. It’s interesting that this film shows ECL response toward trinitrotoluene (TNT), which can be used for the TNT determination based on the ratio luminescence method. Therefore, this work gives a successful paradigm for the fabrication of an E-RET system by loading two-component photoactive species within the 2D LDHs matrix.