Preparations And Properties Of Hybrid Nanocrystals Au-M_xSe(M=Cu, Ag) In Water By Template Method

Gold and Selenium nanomaterials both are of excellent properties, and can be applied to photoelectronic devices and biomedicines. Hybrid nanomaterials composed of Gold and Selenium nanomaterials can not only obtain multi-properties, but also achieve improvement of those properties by Schottky effect and Surface Plasmon Enhancement effect. So Au-Selenium semiconductor nanomaterials arouse great attentions at home and abroad.Those multi-properties of Au-Selenium semiconductor nanomaterials are related to their sizes, morphology and structures. Thus, the key to enhance properties of Au-Selenium nanomaterials is to find an efficient sample method to synthesize these hybrid nanomaterials. So this thesis mainly focus on the synthesis of Au-（copper-group） Selenium nanomaterials and obtain a few innovative results:1) We discover a new method to prepare Au-（copper-group） Selenium nanomaterials.This method is based on Selenium-Template to coat Au seeds with shell Selenium nanomaterials. The whole process can be realized in pure water under room temperature and atmospheric pressure conditions. Compared with previous reports,our synthesis method is sample and environmentally friendly.2) We synthesize a core-shell nanomaterial Au-Cu_2-x Se. The optimal conditions of preparing uniform core-shell Au-Cu_2-x Se nanomaterials are obtained after studying several significant reaction parameters, such as reactant concentrations, surfactant concentrations, reaction times, reactant ratios and so on. By analysis of the reaction intermediates, we propose a formation mode for the core-shell nanomaterial Au-Cu_2-xSe.3) We prepare asymmetrical core-shell nanostructure Au-Cu_2-xSe using quaternary ammonium surfactants. By comparing different kinds of compounds containing quaternary ammonium surfactants, the important role of ammonium functional group in the formation of asymmetrical core-shell Au-Cu_2-xSe nanocrystal is confirmed.After modifying Au nanoparticles with different surfactants twice times, we figure out the interfacial interaction between core and shell, finally we propose a formation mechanism for asymmetrical core-shell Au-Cu_2-xSe nanocrystal: blocking Cu_2-xSe nucleating on the Au surface.4) We succeed to apply this synthesis method on other different core-materials and shell-materials with the same growth mode. Symmetrical and asymmetrical core-shell Au-Ag₂ Se nanomaterials are successfully obtained by adjusting different surfactants,which demonstrates the value of this synthesis method.This thesis may provide new ideas on design and synthesis of hybrid nanostructure materials, and those basic researches about the growth-situation,reaction process and interaction between core and shell are of great value to other nanomaterials.