Gold nanorings synthesized via a stress-driven collapse and etching mechanism

Toroidal Au or Ag nanostructures are of particular interest due to their unique optical responses and superior catalytic applications. However, the fabrication of ring-like Au or Ag nanostructures is limited to either electron beam lithography or template techniques, thus hampering their applications. Here, we present a new stress-driven structure collapse and etching mechanism to synthesize Au nanorings via a direct one-pot solution-based chemical reaction. The nanoparticle-mediated recrystallization process contributes to the formation of Au nanoframes, which contain unusual stress, thus promoting the breakup of the nanoframes and finally converting them into Au nanorings. The Au nanorings with tunable hole sizes exhibit interesting localized surface plasmon features owing to the coupling of bonding and antibonding modes on the inner and outer surfaces of the nanorings. This facile approach may open the door for the preparation of toroidal nanostructures in other compositions for numerous applications. A new strategy for synthesizing gold nanorings that employs stress-driven structure collapse and etching has been demonstrated. Gold nanorings exhibit unique optical and catalytic properties and are used in a wide range of applications, but the synthesizing ways suffer from significant limitations. Now, Jixiang Fang of Xi'an Jiaotong University in China and co-workers in China and Singapore have exploited a simple way to fabricate gold nanorings that involves the formation of frame structures by recrystallization mediated by nanoparticles. The unusual stress distribution in these frames causes them to collapse into nanoring structures. The size of the central hole of the nanorings can be tuned from hundreds to tens of nanometres, allowing the nanorings' optical properties (in particular, their plasmonic properties) to be tailored. A new stress-driven structural collapse and etching mechanism for the synthesis of Au nanorings via a direct one-pot solution-based chemical reaction is presented. The nanoparticle-mediated recrystallization process contributes to the formation of Au nanoframes that contain unusual stress, which promotes the breakup of the nanoframes and conversion into Au nanorings. The Au nanorings have tunable hole sizes and exhibit interesting localized surface plasmon features owing to the coupling of bonding and antibonding modes on the inner and outer surfaces of the nanorings.