Morphological control and plasmonic tuning of nanoporous gold disks by surface modifications

We report a surface modification protocol to control nanoporous gold (NPG) disk morphology and tune its plasmonic resonance. Enlarged pore size up to !20 nm within 60 s dealloying time has been achieved by adsorbing halides onto alloy surfaces in-between two dealloying steps. In addition, plasmonic resonance has been significantly red-shifted by up to !258 nm by the surface modification. Furthermore, with the enlarged pore size, small gold nanoparticles have been effectively loaded into the pores to enhance the performance of surface-enhanced Raman scattering (SERS) due to hot spot formation between the original nanoporous network and loaded nanoparticles.