The shape, size, structure, and composition of the nanostructures determine the properties and applications. The presence of various ions has been shown to influence the shape and size of metallic nanostructures produced via the polyol method. The presence of copper(I) or copper(II) chloride in the polyol reduction of silver nitrate allows the production of silver nanowires.

Silver nanowires have been attracting more and more attention because of their intriguing electrical, thermal, and optical properties. Silver has the highest electrical conductivity among all the metals, by virtue of which Ag NWs are considered as very promising candidates in flexible electronics. Ag nanowires can be used as information guide fibers – in analogy to optical fibers – which may be integrated into micro- and nanoelectronic circuits. Production of silver nanowires, is of great significance because it a most promising candidates to be used as conductive fillers of high-performance adhesives and as catalyst.

Synthesis

For the synthesis of silver nanowires, plenty of chemical routes have been developed. Silver nitrate is reduced by ethylene glycol in the presence of poly(vinylpyrrolidone) (PVP) and copper(II) chloride by a simple synthesis using polyol method.

Ethylene glycol is polyol used in this synthesis as both the reducing agent and solvent. Ethylene glycol (5 mL) is heated at 150°C for one hour with stirring (260 rpm) in disposable glass vials placed in an oil bath. 40 μL of a 4 mM CuCl2•2H2O/ethylene glycol solution is added and heated for 15 minutes. 1.5 mL 114 mM PVP/ethylene glycol is then added to each vial, followed by 1.5 mL 94 mM AgNO3/ethylene glycol. The reaction is stopped when the solution becomes gray and wispy, after approximately one hour. The reaction is stopped by cooling the vials in cold water and the product is washed once with acetone and three times with deionized water to get nanowires of relatively uniform shape and size. The wires have a pentagonal cross-section with an average length of 10-50 μm. The yield of wires is high at 90% compared to other structures.
A variety of other surfactants (capping agent) have been developed to guide the anisotropic growth of silver nanowires and the chemical method has been the most promising way for the large-scale fabrication of silver nanowires.