Controllable Synthesis And Properties Of CdSe Nanostructures

In this dissertation,exploring novel synthetic methods could lead to the formation of polyhedral-,flower-,and rod-shaped CdSe nanocrystals(NCs)and reduced graphene oxide-cadmium selenide(RGO-CdSe)nanocomposites by choosing different kind of green solvents,reactants and surfactants.The as-synthesized products are characterized and investigated by transmission electron microscopy(TEM),powder X-ray diffraction(XRD),transmission electron microscopy(HRTEM),scanning electron microscopy(SEM),x-ray energy dispersive spectrum(EDS),x-ray photoelectron energy spectrum(XPS),uv-vis diffuse reflectance spectrophotometry,high-resolution fourier transform infrared spectroscopy(FT-IR),ram an spectrum,zetasizer,contact angle measurement.The main results are as follows:1.Size-controlled colloidal CdSe polyhedra with wurtzite(hexagonal)crystal structure were synthesized by a simple one-pot solid/liquid-phase reaction with the use of K[CdCl3]and Se powder directly as precursors in reaction medium containing small amount of oleic acid as the capping ligand,dodecylamine(DDA)as the reducing agent and 1-octadecene as solvent.The obtained CdSe polyhedra exhibited good electrogenerated(ECL)performance with two emission peaks at about-1.33 V and-1.94 V.The CdSe polyhedra also displayed an electrochemical photoresponse indicative of a n-type semiconductor.The influence of various experimental variables,including nature of Cd precursors,reaction temperature,nature and amount of surfactants,the nature of reducing agent,on the morphology and structure of the obtained CdSe NCs have been systematically investigated.2.In this communication,we demonstrated the dissolution of SeO2 in terpineol at room temperature,which generated soluble Se(-?).Herein,a new method that used the soluble Se(-?),Cd(Ac)2 and harmless DMPU as the coordinating solvent and eliminated the need for air-sensitive and toxic trioctylphosphine(TOP)was presented for the synthesis of CdSe NCs with Zinc Blende(cubic)crystal structure.The assynthesized CdSe NCs could be dissolved in polar and nonpolar solvent and possessed promising photoresponsive properties.Moreover,CdSe NCs with wurtzite(hexagonal)crystal was generated with the use of K[CdCl3]as Cd precursor.3.RGO-CdSe nanocomposites were sueeessfully prepared by a novel and simple one-pot solid/liquid-phase reaction.During this reaction,GO was reduced to RGO while Se was oxidized to Se2-.The morphological and structural characterizations evidenced that the single-crystal CdSe polyhedra NPs with the size of a few tens of nanometers can be efficiently decorated on the RGO.The graphene-CdSe composite efficiently catalyzed the photodegradation of 4-chlorophenol(4-CP),methylene blue(MB),and rhodamine B(Rh.B)in aqueous solution under UV light irradiation.Moreover,the photoresponse of this nanocomposite was drastically enhanced to 15?A compared with that of the pure CdSe NPs,the bare RGO.The outstanding photocatalytic and photoresponse performance was associated with the good electrical conductivity and effective charge separation because of the presence of RGO.The present work makes the RGO-CdSe NPs nanocomposite a great promise for wide potential applications in optoelectronics.