Synthesis of Au/Ag nanoframes from Ag nanoplates by galvanic replacement reaction and its optical properties

• Au/Ag nanoframes (Au/AgNF) were prepared by galvanic replacement reaction (GRR) of Ag nanoplates.
• By pre-oxidation and GRR, Au/AgNF with 65/35 ratio of Au/Ag was obtained.
• The dipole peak further red-shifted than quadrupole peak, found at NIR region.
• An optical change was confirmed with discrete dipole approximation simulations.

Metallic hollow nanostructures, prepared using a galvanic replacement reaction (GRR), give rise to hot-spots in electromagnetic fields, due to plasmon coupling between their interior and exterior surface fields. Herein, Au/Ag triangular nanoframes (Au/AgNF) were prepared by a galvanic replacement reaction (GRR) of Ag nanoplates with HAuCl4 in an aqueous solution for 5 min. Through sequential processes of pre-oxidation and GRR, Au/AgNF with 65/35 ratio of Au/Ag was obtained. An optical change in the UV–vis spectra was confirmed with discrete dipole approximation simulations. The dipole peak of Au/AgNF further red-shifted than the quadrupole peak, found at near-infrared region.