Rapid Preparation of Silver Nanorods and Nanowires by a Microwave-Polyol Method in the Presence of Pt Catalyst and Polyvinylpyrrolidone

Abstract

Silver nanorods and nanowires have been synthesized by using a microwave (MW)-polyol method. When AgNO3 was reduced by ethylene glycol (EG) in the presence of Pt seeds and a long chain length of poly(vinylpyrrolidone) (PVP: Mw = 360 k), mixtures of one-dimensional (1-D) silver nanorods and nanowires and three-dimensional (3-D) spherical, triangular-bipyramidal, and cubic nanoparticles were synthesized within a few minutes. The average diameters, lengths, and yields of these products were measured as a function of concentration of Pt, PVP, or AgNO3, heating time, or MW power to determine optimum conditions for the synthesis of 1-D products. 1-D products could be easily separated from other 3-D nanoparticles by repeating centrifugal separation in water. Longer and thicker 1-D products could be prepared by using 1-D products as seeds and repeating the reduction of AgNO3 in EG under MW irradiation. In this two-step preparation, some bent 1-D wires due to the combination of {111} facets of two rods and wires were produced. Possible growth mechanisms of 1-D products involving bent structures, and 3-D spherical, triangular-bipyramidal, and cubic nanoparticles were discussed by reference to growth mechanisms of Au core-Ag shell nanocrystals prepared using the two-step MW polyol method.