Shape evolution and gram-scale synthesis of Gold@Silver core-shell nanopolyhedrons

Au@Ag heterometal core-shell nanoparticles with distinct polyhedral shapes were successfully synthesized by a seed-mediated polyol process on a gram scale. The addition of the silver precursor solution led to continuous shape evolution from gold seeds to silver spheres, cuboctahedrons, and cubes, respectively. Silver nanocubes were also grown by selective edge growth on gold cuboctahedral seeds. The overgrowth of silver shells could precisely tune the optical properties of the core-shell polyhedrons. Interestingly, a large red-shift of the extinction peak from that of the gold seeds was observed in the Au cuboctahedron@Ag cubes, reflecting a combination of composition and shape effects.