Open AccessIodide Ions Control Seed-Mediated Growth of Anisotropic Gold Nanoparticles
Author(s) -
Jill E. Millstone,
Wei Wei,
Matthew R. Jones,
Hyojong Yoo,
Chad A. Mirkin
Publication year - 2008
Publication title -
nano letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.853
H-Index - 488
eISSN - 1530-6992
pISSN - 1530-6984
DOI - 10.1021/nl8016253
Subject(s) - iodide , bromide , rod , pulmonary surfactant , yield (engineering) , nanotechnology , chemistry , anisotropy , facet (psychology) , ion , nanoparticle , crystallography , colloidal gold , materials science , chemical engineering , chemical physics , inorganic chemistry , organic chemistry , physics , composite material , optics , biochemistry , medicine , social psychology , psychology , alternative medicine , personality , pathology , engineering , big five personality traits
There are now a variety of preparatory procedures for nanoscale gold rods, triangular prisms, and spheres. Many of these methods rely on seed-mediated approaches with cetyltrimethylammonium bromide (CTABr) as a surfactant. Interestingly, seemingly similar preparatory procedures yield very different morphologies, and although there have been a variety of proposals regarding the importance of different steps in shape control, there is no self-consistent procedure that allows one to take one batch of spherical seeds and grow either rods, prisms, or larger polyhedra in a controlled manner. In this report, it is shown that CTABr, depending upon supplier, has an iodide contaminant (at a significant but varying level), which acts as a key shape-directing element because it can strongly and selectively bind to the Au (111) facet and favor the formation of anisotropic structures. Furthermore, by starting with pure CTABr and deliberately adjusting iodide concentration, one can reproducibly drive the reaction to predominantly produce one of the three target morphologies.