Study On Controllable Synthsesis Of Silver Nanowires,Their Properties And Applications

Silver nanowires(AgNWs)have got much attention due to their promising applications in various fields such as conductive composites,nano electronic devices,surface enhanced Raman spectroscopy(SERS)and so on.Many researches focusing on AgNWs have been reported in the past decade.A number of techniques have been applied for successful synthesis of AgNWs.Solution based polyol process was proved as one of the dominant approach for the fabrication of AgNWs.The different experimental parameters have been studied which directly influenced the final morphology of AgNWs.However,the research on the development of an efficient synthetic approach of AgNWs is still in progress to accomplish the need of advance technology for controlled morphology of AgNWs.In our research,we focused on the synthesis of AgNWs via modified polyol method and their roles as conductive material in conductive thin films and SERS spectroscopy were studied.1)The presence of cations and anions in the reaction solution have influence on the final morphology of AgNWs during polyol method.Here we report a feasible way to prepare AgNWs by polyol method.CuBr2 salt was used to provide anions and cations in the reaction solution.The anions(Br-)helps in reducing the amount of free Ag+by forming AgBr during initial silver seeds formation and the cations scavenge oxygen from the surface of AgNWs during preferential growth of the AgNWs.Ethylene glycol was used as a solvent and reducing agent,silver nitrate was used as Ag source and polyvinyl pyrrolidone(PVP)was used as a capping agent.The effects of various factors which influence the final morphology of AgNWs were studied.AgNWs were successfully synthesized in the presence of CuBr2 salt.The morphology of the synthesized AgNWs was characterized by the scanning electron microscope(SEM)and transmission electron microscope(TEM).The crystallinity was characterized by high resolution transmission electron microscope(HRTEM),selected area electron diffraction pattern(SAED)and X-ray diffraction(XRD).The surface plasmon resonance(LSPR)peaks of Ag nanostructures were revealed by UV-Vis spectroscopy.The conductive properties of AgNWs thin conductive films were studied by coating them on a polyethylene terephthalate(PET)substrate.2)AgNWs with high uniformity and controlled morphology were synthesized by employing silver nitrate as Ag source,ethylene glycol as reducing agent and solvent,and PVP as capping agent.The synthetic process was carried out in salt free environment.The effects of reaction parameters like concentration of AgNO3 and the reaction temperature on the final morphology of AgNWs were studied.AgNWs were successfully prepared by varying different reaction conditions and their morphology was characterized by SEM and TEM.Their crystalline nature was characterized by HRTEM,SAED,XRD and their LSPR peaks was revealed by UV-Vis spectroscopy.The synthesized AgNWs were coated on a PET substrate by spin coating method to make thin conductive film.The AgNWs film was found to have low sheet resistance.3)High molecular weight PVP and seeding conditions are considered to have important roles in the synthesis of AgNWs.In this work,we report a versatile synthesis of AgNWs in a salt free environment and under Ar inert atmosphere using high molecular weight PVP and seeding step during the synthetic process.The high molecular weight PVP was found to efficiently promote the preparation of AgNWs via supporting the proper growth control of AgNWs on {111} facets and selective growth on {100} facets.Seeding step facilitates the formation of seeds like multiple twinned nanoparticles(MTPs)and single crystal seeds,which promoted the feasible formation of AgNWs.The shape and size of the synthesized AgNWs were characterized by SEM and TEM.The crystalline nature of the synthesized AgNWs was characterized HRTEM,SAED and XRD,and their LSPR peaks were confirmed by UV-Vis spectroscopy.The conductive properties of the synthesized AgNWs were determined by preparing their thin conductive film on a PET substrate.The prepared AgNWs thin films exhibited good sheet resistance.4)Herein,we had used a simple conventional polyol method and synthesized AgNWs feasibly in 40 min under Ar.inert atmosphere,without using any inorganic salts and only high molecular weight PVP was used as a capping and growth controlling agent,ethylene glycol as a solvent as well as a reducing agent and silver nitrate as a Ag source.The polyol synthesized smooth surface AgNWs were then subjected to chemical etching,using aqueous ammonia and 30%hydrogen peroxide as an etchant materials and corrugated surface AgNWs were successfully prepared.The synthesized corrugated surface AgNWs were used as a surface enhancement materials to increase the intensity of the Raman signals and the surface enhancement properties of the corrugated surface AgNWs were studied by using rhodamin 6G as probe molecule via SERS sensing technique.The corrugated surface AgNWs had obviously increased the surface enhancement of the probe molecule and resulted in strong intensity SERS signals.