One-pot synthesis of gold nanorods via autocatalytic growth of sonochemically formed gold seeds: the effect of irradiation time on the formation of seeds and nanorods.

A one-pot synthesis for gold nanorods was developed using sonochemical reduction of gold ions in an aqueous solution in the presence of cetyltrimethylammonium bromide, silver nitrate, and ascorbic acid, where we focused on the autocatalytic growth of gold seeds formed by ultrasonic irradiation for short times. In growth experiments with these sonochemically formed gold seeds, sigmoidal shape growth curves were observed, and the induction period before growth began was longer for shorter irradiation times. This result indicated that the number of sonochemically formed gold seeds increased with increasing irradiation time. The average aspect ratio of the gold nanorods produced changed from 2.0 at an irradiation time of 0.5min to 3.6 at 15min. The gold nanorods produced were longer and wider when the irradiation time was shorter.