“…6 Au or Ag nanorings also exhibit substantial increases in bulk refractive index sensitivity relative to those of nanodisks with similar diameters, 7 remarkably uniform field intensity enhancements for surface-enhanced Raman scattering, 8 enhanced second harmonic generation at near infrared frequencies 9 and superior catalytic activities. 10 To date, Au or Ag NPs with various shapes, such as nanospheres, nanobars, nanorods, nanorices, nanoneedles, nanowires, nanocubes, nanoprisms, bipyramids, nanocarrots, nanoplates, nanodisks and nanobelts, have been successfully prepared. 11 However, the fabrication of ring-like Au or Ag nanostructures is limited to either electron beam lithography or template techniques.…”