Nanoscale Kirkendall effect induced void formation in Au–Ag nanostructures and their application as SERS substrate

Abstract

Triangular-shaped silver nanostructures were synthesized via a seed-mediated two-step method. A galvanic replacement reaction coupled with the Kirkendall effect was employed to transform Ag nanostructures into porous Au–Ag structures having voids at the nanoscale. Compared with previous reports, the medium and the binding agent used in the synthesis of silver nanoparticles employed as templates play a vital role in determining the extent of nanoscale voids formed due to the Kirkendall effect. Raman activity of these porous structures was tested with crystal violet as the probe molecule, and it was found that the Raman enhancement factor varies with cathode concentration.