Synthesis Of Silver Nanowires By Solvothermal Method And Tuning Of Their Aspect Ratio Parameters

One-dimensional metallic nanomaterials are a class of materials made of metals in two of the three dimensions between 1-100 nm（e.g.,silver nanorods,silver nanowires,gold nanorods,etc.）.Due to their special structures,one-dimensional metallic nanomaterials have a wide range of applications in sensing,imaging,plasmonics,photonics,displays,heat treatment,and catalysis.Among them,silver nanowires are widely used in many research fields such as microelectronic devices,catalysis,solar cells and biosensors because of their high electrical conductivity,thermal conductivity and flexibility,which have attracted great interest from researchers.Currently,there are disadvantages in the synthesis of silver nanowires such as complicated operation,uncontrollable aspect ratio,and unfriendly raw materials.Therefore,in this thesis,the synthesis of one-dimensional silver nanowires was investigated by using ethylene glycol and water as solvents,which are simple to operate and can be applied to industrial production,respectively.The specific studies are as follows:（1）The solvent thermal method was applied to analyze the nanowire aspect ratio variation pattern by SEM,HRTEM,XRD and UV-Vis tests at 130°C with ethylene glycol as the solvent,PVP as the capping agent and silver nitrate as the silver source to investigate the mechanism of different metal salts（MCl_x）regulating the synthesis of ultra-high aspect ratio silver nanowires.It was proposed that Mⁿ⁺and Cl^-would jointly promote the synthesis of silver nanowires,and the silver nanowires with the thinnest average diameter of 42 nm and the longest average length of 367μm were successfully synthesized.The results show that the greater electronegativity and electron gaining ability of metal ions will slow down the reduction rate of silver ions in the system and lead to smaller diameter silver nanowires.（2）The effects of adding the amount of H₂O₂,the type and concentration of Cl^-,the type and concentration of PVP,the reaction temperature and p H on regulating the length-to-diameter ratio of silver nanowires were investigated by the solvothermal method with the environmentally friendly raw material water as the solvent,silver acetate as the silver source and H₂O₂ as the growth aid with the help of sodium chloride.The results showed that elongated silver nanowires with an average diameter of 22 nm and a length of more than 100μm were synthesized under the reaction at 160°C for 22h and the molar ratio of H₂O₂:Na Cl:Ag=21.5:2:1.