Synthesis of Nanowire-Shaped Silver by Polyol Process of Sodium Chloride

Abstract

Nanowire-shaped silver have been synthesized by the polyol process in ethylene glycol as a reductant, poly- vinylpyrrolidone (PVP) as a stabilizer, using a microwave technique. The products were characterized by transmission electron microscopy (TEM). The presence of sodium chloride in the polyol reduction of silver nitrate facilitated the pro- duction of silver nanowires. These wires were formed quickly (in approximately 3 minutes microwave heating). It was found that morphologies and sizes of silver nanostructures depended strongly on such experimental parameters as concentrations of PVP, NaCl, AgNO3, and heating time. The chloride ion was necessary to synthesize nanowire-shaped silver, and the sodium chloride likely controlled the rate of silver(I) reduction and initial seed formation. Among all the nanowire materials, the synthesis of silver nanowires has been and continues to be an area of active research because of their wide applications in catalysts, scanning probes, and various kinds of electronic and photonic nanodevices. Microwave-polyol method is a promising route for rapid preparation of metallic nanomate- rials(1). When microwave was irradiated into the mixture of AgNO3/NaCl/PVP in ethylene glycol solution, anisotropic Ag nanarods and nanowires were produced preferentially. In this work, we examined the dependence of shape, size of silver nanostructures on such experimental parameters as concentrations of PVP, NaCl, AgNO3, and heating time. The changes of shapes and sizes of silver nanostructures were observed by using transmission electron microscope (TEM). Possible formation mechanism of nanorods, nanowires, spherical and cubic nanoparticles under microwave (MW) irradiation in the presence of sodium chloride was discussed.