Preparation And Photoelectric Properties Of Selenium-based Nanomaterials

Photoelectric materials have been research hotspot in the field of materials, due to their special optical and electrical properties. Recently, the nanocomposites with optical and electrical properties have attracted much attention, since they possess wide application prospect in optoelectronic devices, chemical analysis, energy and catalysis. In this thesis, a series of selenium-based nanocomposites were prepared by simple methods. The morphology and constituents of the nanocomposites were characterized by Scanning electron microscope (SEM), Transmission electron microscopy (TEM), X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), Ultraviolet-Visible Spectrophotometer (UV-vis) and Fluorescence Spectrometer (FL). Significantly, the electrochemical properties, electrochemiluminescence (ECL) behavior, nonlinear optical properties, adsorbent and catalyst properties of the nanocomposites were studied, respectively.The main contents are as follows:1. Electrochemiluminescence sensor based on Graphene Oxide/Polypyrrole/CdSe nanocompositeA novel approach of ECL enhancement was based on the Graphene Oxide/Polypyrrole/CdSe (GO/PPy/CdSe) nanocomposite that was prepared by a simple method. The products were examined by SEM, TEM, UV-Vis, FTIR, FL and impedance analysis, respectively. The ECL sensor was obtained by modifying the GO/PPy/CdSe nanocomposite on the surface of glass carbon electrode. The ECL mechanism and effect factors were also discussed. The results show that the ECL sensor as-prepared has strong ECL intensity, stable ECL emission and good biocompatibility. The ECL sensor was used to detect dopamine (DA), and the detection linear range for DA is from 0.01 to 16 nM with the detection limit of 0.004 nM.2. Enhanced electrochemiluminescence of CdSe quantum dots coupled with MoS2-chitosan nanosheetsA new ECL sensor based on the molybdenum sulfide/chitosan/CdSe quantum dots (MoS2/CS/CdSe QDs) nanocomposite was prepared, in which the nanocomposite was obtained by mixing MoS2/CS composite solution with CdSe QDs solution under mild sonication. The experiment results show that the ECL sensor as-prepared has high ECL intensity, long-time ECL stability and good biocompatibility. The mechanism and effect factor were discussed. The sensor made up of the MoS2/CS/CdSe QDs nanocomposite showed good sensitivity and selectivity to uric acid (UA), and the results indicate that the detection linear range for UA is from 0.10 to 140 nM with the detection limit of 0.04 nM. In addition, this ECL sensor has successfully been used in determining the uric acid in urine sample.3. Self-catalytic polymerization of a water-soluble selenium/polypyrrole nanocomposite and its nonlinear optical propertiesA water-soluble selenium/polypyrrole (Se/PPy) nanocomposite was prepared by using pyrrole as a reductant for the reduction of H2SeO3 in mild conditions. During the reaction, the elemental Se formed in situ acted as a catalyst for the polymerization of pyrrole. The products were characterized by SEM, TEM, XRD, FTIR, UV-vis, Raman, TGA, XPS and EIS, and the results show that the Se/PPy nanocomposite is made up of uniform spherical particles with about 80 nm in diameter. The mechanism, effect factor and water-solubility were discussed. The results of Z-scan test show that the Se/PPy nanocomposite has a large two-photon absorption (2PA) cross-section and good optical limiting properties due to the synergistic effect of photo-conductive Se nanoparticles and electric-conductive PPy molecules, which made the nanocomposite potential application in nonlinear optics field.4. Facile synthesis and application of hexagonal Ni0.85Se nanosheetsThe Ni0.85Se nanosheets were successfully prepared by a solvothermal method. The product was characterized by XRD, SEM, TEM, UV-vis, FL and thermogravimetry, and the results show that the product is made up of Ni0.85Se nanosheets with hexagonal phase. In presence of NaBH4, the Ni0.85Se nanosheets have excellent adsorption to methylene blue (MB) and catalytic activity to the hydrogenation of p-nitrophenol (PNP). Significantly, it was found that the Ni0.85Se nanosheets can be used to treat the mixture solution of MB and PNP.