Synthesis Of One-Dimension Silver Nanomaterials In Aqueous Solution

Silver nanomaterials are one of the most widely used materials in the fields of photoelectricity,catalysis and biology.Among them,one-dimensional silver nanostructure materials such as silver nanorods and silver nanowires play a vital role in the applications of Surface-enhanced Raman spectroscopy(SERS)and transparent conductive films.Currently,polyol synthesis has been the most popular method for preparing silver nanomaterials,but accompanying with numerous organic liquid producing,which is difficult to recycle and the emission of them will cause great destruction to the ecological environment.Therefore,in order to comply with the environmental friendly concept,we have developed a water-based synthesis method of silver nanorods/wires and deeply investigated the effects of surfactants,ammonia,acid and etc on the synthesis of silver nanorods/wires in aqueous solution.Research contents are as follows:1.Au nanodechedra were used as seeds for synthesis of Au-Ag heterostructure nanorods in aqueous solution.The growth reaction conditions of nanorods were investigated by adjusting the molar ratio of ascorbic acid and Ag NO₃,and then we introduced ammonia into the growth solution to explore the effect of increasing p H value on the morphology of the product.The addition of ammonia inhibited the formation of silver halide as a by-product.By combining the synergetic effect between NH₃·H₂O and bromide ion,the highly constrained growth along the side direction of silver nanorod and synthesis of ultrathin nanorod could be achieved with the diameters of 16 nm and the lengths of 210 nm.2.Au@Ag nanorod was used as seeds for synthesis of Ag nanowires with high aspect ratio in aqueous solution.Three kinds of inorganic acids(HNO₃,HCl,H₂SO₄)were added into the growth solution to reduce the p H value and investigate the effect of products.After choosing the types and adding amounts of acids,the ultrathin silver nanowires with a diameter of 17 nm and the aspect ratio of 1000 were obtained.In addition,the effects of reaction temperature,dropping rate and the molar ratio of ascorbic acid to Ag NO₃ on the morphology of the products were also compared.It was proved that a slower reduction rate is more conducive to the construction of highly anisotropic structures.Finally,silver nanowires were purified by an improved flocculation precipitation method,and the morphology yield of purified silver nanowires was up to 95%.