Study On The Controlled Synthesis And SERS Properties Of Silver Nanoparticles

Due to the excellent physical and chemical properties, nanosilver particles can bewidely used in anti-static, catalytic, bio-sensor, antibacterial and electronic paste andmany other fields. The properties of silver nanoparticles mainly depend on its shape andsize, so many research institutions focus on the controllable preparation of nanosilverparticles. Three kinds of different nanosilver particles-silver nanoplates, silver nanorodsand silver nanowires, have been successfully prepared by hydrothermal oralcohol-thermal methods. Their conductivity and surface-enhanced Raman scattering(SERS) effects have been characterized by multimeter and Raman spectroscopy.Hydrazine hydrate, N, N-dimethylformamide (DMF) and ethylene glycol were used as thereducing agents respectively, Process parameters such as reaction tempreture–havegreat effect on the final the morphology and size of the silver particles. On this basis, theelectrical properties of the nanosilver particles, and the surface-enhanced Ramanscattering (SERS) with different morphologies nanosilver as a substrate were researched.The following aspects were researched:Using DMF as reducing agent and dispersing agent, silver nitrate as silver source andPVP as a protective agent, with hydrothermal method, reaction conditions was at150℃for7h. FeCl3as the inhibitor was then added into the system, and stably dispersed silvernanoflake with homogeneous morphology was prepared finally. The impact factorsincluding the reaction time, reaction temperature and the concentration of silver nitratewere researched on the preparation of nanosilver morphology. The results showed thatwhen the reaction time is7h the particle size of nanosilver plates is under200nm whilethe size distribution range is relatively wide; and when the reaction time was10h the sizedistribution range is relatively narrow; when the reaction temperature is at150℃, theprepared nano-silver plates were thin; when the reaction temperature is at160℃, thenano silver is relatively thick; the dispersion stability of silver nanoparticles are better withlower concentrations of silver nitrate, with increased concentration of silver nitrate, silvernanoplates have trend of overlap with each other. PVP was used as protective agent and the weakly reducing agent, silver nitrate assilver source with alcohol-thermal method. The high aspect ratio silver nanowires withuniform morphology were rapid prepared at160℃. The impact mechanism of the NaCland NaBr to the morphology of nanosilver was studied. The factors including the Cl-concentration and feeding methods were also researched. When the concentration ofNaCl is0.2μM, the diameter of silver nanowire is about100nm, a length of about20μm;nano silver rod diameter of about200nm, a length of about3μm.The prepared nanosilver dispersion with various morphologies were prepared aspurified surface-enhanced Raman scattering (SERS) substrate, and the relationshipbetween the morphology and surface-enhanced Raman scattering (SERS) characteristicsof silver nanoparticles was preliminary studied. R6G was selected as probe molecules.The silver nanowires exhibit excellent SERS properties.The conductive properties of the prepared silver nanowires were preliminaryanalysised. The prepared silver nanowires dispersion was purified, then coated with ascrew membrane and tested with a multimeter to investigate their conductive properties.The resistance value of the coating layer of silver nanowires is reduced to about15Ω.,with content of3.94%coated with7#screw and sintered at120℃for10min.