Synthesis of shield-like singly twinned high-index Au nanoparticles.

A new gold nanostructure--shield-like Au nanoparticles (NPs) with a single twin plane and high-index {hhl} facets--was discovered in a simple seed-mediated synthesis. The development of this new shape is believed to be due to the preferential adsorption of cetyltrimethylammonium cations (CTA(+)) on high-index facets and the coalescence of the NPs by the charge screening effect of NaCl. These shield-like Au NPs display some properties that are distinctively different from other types of Au NPs.