Influence of silver ions on the growth mode of platinum on gold nanorods

Abstract

Gold nanorods were used as seeds for platinum growth, using a mild reducing agent, ascorbic acid, in the presence of the cationic surfactant cetyltrimethylammonium bromide (CTAB). Highly preferential growth on the tips or complete overcoating can be achieved by manipulation of the reduction conditions, among which the presence of silver ions was found to be highly dominant. In either case, the growth was found to be epitaxial, as demonstrated by high resolution electron microscopy and Fourier transform analysis. Additionally, the deposition mode leads to very different effects on the optical properties of the nanoparticles, with tip growth inducing huge surface plasmon red shifts.