Shape controlled gold nanostructures on de-alloyed nanoporous gold with excellent SERS performance

Highlights: • Nanoporous gold was prepared from Au-based amorphous alloy by de-alloying. • Shape controlled Au nanostructures on NPG were achieved by electrodeposition. • The Au dendritic nanostructure exhibited high SERS effect and reproducibility. • For melamine sensing, the detection limit of 10⁻⁷ M was achieved. In this study, chemical de-alloying method was used to prepare nanoporous gold (NPG) from the Au containing amorphous alloy, with chemical composition of Au₂₀Cu₄₈Ag₇Pd₅Si₂₀. Gold nanostructures were electrodeposited on the nanoporous gold by adjusting the applied potentials and deposition times. Using Rhodamine 6G (R6G) as probe molecule, the surface enhanced Raman scattering (SERS) activity of various Au nanostructures on nanoporous gold were compared. The dendritic nanostructures electrodeposited for 3000 s on NPG exhibited strongest SERS effect and high reproducibility. Using this best SERS active substrate for melamine sensing, the detection limit of 10⁻⁷ M was achieved.