Shape Control of Ag Shell Growth on Au Nanodisks

Core–shell (Au@Ag) bimetallic nanoparticles containing a Au nanodisk in the core were synthesized using Au nanodisks as seeds. The growth direction of the Ag shell on the gold nanodisks could be tuned by the presence of iodide ions. Without the I – ions, the Ag shell was formed homogeneously over the entire surface of the flat Au nanodisks, while the presence of I – induced the selective coating of the Ag shell in the direction perpendicular to the basal plane of the nanodisks. The resulting core–shell (Au@Ag) bimetallic nanoparticles could be further converted to hollow nanostructures containing a central Au nanodisk via galvanic replacement reactions.