Facile synthesis of Au-Ag core-shell nanoparticles with uniform sub-2.5 nm interior nanogaps

A facile method was established to fabricate uniform nanogaps between a Au core and a Au-Ag alloy shell. The size of nanogaps is controllable due to fast dissolution of AgCl and AgBr in CTAB and the crystal growth of the shell on a designed template. These Au-Ag core-shell nanoparticles with uniform sub-2.5 nm interior nanogaps can be potentially used for various applications.