Formation of metal-selenium and selenide nanoparticles using distinct reactivity with noble metal ions

Abstract

In this thesis, Ag2Se nanoparticles could be synthesized by controlling Se precursors at low temperature (263 K) and the cation exchange reactions were used as generic approach to transform Ag2Se to CdSe, ZnSe, and PbSe nanoparticles. Same process of Ag2Se nanoparticles was also used for Pt@Se and Au/Se nanoparticles synthesis. Recently, many studies in this area focused on selenium particles over 100 nm or less than 10 nm in size because Se templates tend to crystallize and grow up into nonspherical shapes. In this research, the use of viscous ethylene glycol (EG) and poly(vinyl pyrrolidone) (PVP) allowed for leading to monodispersed particles and preventing any possible agglomeration. A solution of SeCl4 and PVP in EG was introduced to NaBH4 solutions at 263 K. NaBH4 solutions were used to reduce Se4+ to Se precursors. And then the reaction vessel was quickly transferred into an oil bath heated at 333 K. When AgNO3 solutions were added, Ag+ was reduced to Ag by NaBH4 and EG. Synthesized Ag was easily reacted with Se precursors, and Ag2Se nanoparticles were produced. Cation exchange reactions were used to synthesize CdSe, ZnSe and PbSe from produced Ag2Se nanoparticles. The synthesis methods for Au/Se and Pt@Se nanoparitlces were same with Ag2Se nanoparticles’ synthesis method. Ag2Se, Au/Se, and Pt@Se nanoparticles were also compared with each other. Ag2Se, Au/Se, and Pt@Se nanoparticles had different shape because of different reaction kinetics. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis spectroscopy. The results of XRD and TEM analyses demonstrated that the products were spherical with orthorhombic (Ag2Se), hexagonal (CdSe, ZnSe), and cubic (PbSe) structures. This approach for Ag2Se, CdSe, ZnSe, and PbSe DCH 20085073 2008507320085073 20085073 ii nanoparticles is efficient and simple to synthesize mesoscale metal calcogenide nanopartcles from selenium templates. P3HT derivatives have received...