Unstable reshaping of gold nanorods prepared by a wet chemical method in the presence of silver nitrate

Abstract

We characterized the stability of the gold nanorods synthesized by means of a seed mediated growth approach in the presence of AgNO3, which consists of synthesis of small diameter seed particles (similar to 4 nm) and subsequent growth of these nanoparticles into nanorods by addition to gold salt solution containing cetyltrimethylammonium bromide (CTAB) in the presence of ascorbic acid. The presence of silver nitrate significantly enhanced the nanorod synthesis as previously reported. However, the synthesized nanorods were unstable and reshaped in aqueous environment; the continuous blue-shift of the 2nd plasmon bands was monitored and the changes in the nanorod morphologies were also observed by electron microscopy with increasing storage time. This reshaping was observed at wide CTAB concentration range regardless of the removal of the unreacted gold or silver ions.