Abstract: Alloyed Ag/Au nanospheres with high compositional homogeneity ensured by annealing at elevated temperatures show large extinction cross-sections, extremely narrow band-widths and remarkable stability in harsh chemical environments. A critical temperature has been found to be around 930° C., below which the resulting alloy nanospheres, although significantly more stable than pure silver nanoparticles, can still gradually decay upon extended exposure to harsh etchant. The nanospheres annealed above the critical temperature show homogeneous distribution of Ag and Au elements, minimal crystallographic defects, absence of structural and compositional interfaces, which account for the extremely narrow bandwidths of the surface plasmon resonance, and may render many plasmonic applications with high performance and long lifetime, especially for those involving corrosive species.

Abstract: A method of preparing a metal nanorod. The method includes seeding a metal nanoparticle within the lumen of a nanotube, and growing a metal nanorod from the seeded metal nanoparticle to form a metal nanorod-nanotube composite. In some cases, the nanotube includes metal binding ligands attached to the inner surface. Growing of the metal nanorod includes incubating the seeded nanotube in a solution that includes: a metal source for the metal in the metal nanorod, the metal source including an ion of the metal; a coordinating ligand that forms a stable complex with the metal ion; a reducing agent for reducing the metal ion, and a capping agent that stabilizes atomic monomers of the metal. Compositions derived from the method are also provided.

Abstract: Alloyed Ag/Au nanospheres with high compositional homogeneity ensured by annealing at elevated temperatures show large extinction cross-sections, extremely narrow band-widths and remarkable stability in harsh chemical environments. A critical temperature has been found to be around 930° C., below which the resulting alloy nanospheres, although significantly more stable than pure silver nanoparticles, can still gradually decay upon extended exposure to harsh etchant. The nanospheres annealed above the critical temperature show homogeneous distribution of Ag and Au elements, minimal crystallographic defects, absence of structural and compositional interfaces, which account for the extremely narrow bandwidths of the surface plasmon resonance, and may render many plasmonic applications with high performance and long lifetime, especially for those involving corrosive species.

Abstract: A method of preparing a metal nanorod. The method includes seeding a metal nanoparticle within the lumen of a nanotube, and growing a metal nanorod from the seeded metal nanoparticle to form a metal nanorod-nanotube composite. In some cases, the nanotube includes metal binding ligands attached to the inner surface. Growing of the metal nanorod includes incubating the seeded nanotube in a solution that includes: a metal source for the metal in the metal nanorod, the metal source including an ion of the metal; a coordinating ligand that forms a stable complex with the metal ion; a reducing agent for reducing the metal ion, and a capping agent that stabilizes atomic monomers of the metal. Compositions derived from the method are also provided.