Study about an Experimental Design for CdTe Quantum Dots Synthesis. Analysis of the Optical Changes after Their Interaction with Hydroxyl Radicals

Wednesday, 4 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
E. C. Muñoz, E. A. Navarrete, V. Rojas, J. Román, R. G. Henríquez, and R. S. Schrebler (Pontificia Universidad Católica de Valparaíso)
Quantum dots (QDs) are semiconductor nanocrystals with diameters in the range of 2-10 nm and which exhibit electronic properties between bulk materials and molecules. Considering their optical properties, fluorescence processes exhibit real applications in sensor and biosensors fields. In fact, the fluorescent properties of these materials can be tuned depending on the particle size. Generally, a decrease of the QDs size produces an increase in the energy gap between the valence and the conduction band, which induces to a shifted of the emission wavelength toward shorter values. In this work we examined an optimization of the synthesis parameters of CdTe QDs using a Doehlert design of experiments. The synthesis employed Na2TeO3 and CdCl2 as precursors, mercaptosuccinic acid (MSA) as capping agent, NaBH4 as reducing agent and Borax/Citrate as buffer in a reflux system. The synthesis parameters optimized were: temperature, pH, molar ratio of precursors and reaction time. After, an analysis of the optical and electrochemical changes after the interaction with hydroxyl radicals was carried out. The optical changes were studied by fluorescence spectroscopy measurements evaluating the fluorescence lifetime. The changes in these properties were studied in absence and presence of hydroxyl radicals produced by a Fenton reaction (unstable radical), and presence of 2,2,6,6-tetramethylpiperidine-1-oxyl radical(TEMPO) (stable radical).