Synthesis of hollow gold nanoparticles and rings using silver templates

Gold nanoshells have gained attention recently due to their versatile optical properties. In particular, their spectrally selective extinction has been exploited for experimental medical applications, functional coatings and contrast enhancement for analytical techniques. Here we discuss nanoshells and the formation of gold nanorings by the galvanic replacement of Ag nanosphere template particles. Hollow Au/Ag nanoshells can be converted to nanorings upon addition of excess HAuCl₄. Nanorings present a distinct particle geometry, with optical properties exhibiting characteristics of both nanorods and nanoshells.