Fabrication of Superior Au-Ag Composites Surface-Enhanced Raman Scattering Active Substrates Based on One-Step Method of Chemical Etching

摘要

Bimetallic silver-gold composites are currently among the most studied substrates for detection based on surface-enhanced Raman scattering (SERS). Here, we developed Au-Ag composite films as high sensitivity, large-scale, chemically stable and reproducible SERS substrates. Au-Ag composite films were fabricated by chemical etching of Ag-Au alloy leaves with HAuCl4 aqueous solutions. Along with galvanic replacement reaction and dealloying, films with distinct microstructural features exhibit dramatic improvement in the SERS intensity. Especially, the Au-Ag composite films with legible nano-ridges fabricated by alloy leaves of 9 carat present the strongest SERS enhancement. The superior SERS enhancement is attributed to the confluence effect of enhanced local surface plasmon fields and electromagnetic coupling within nanogaps, sharp edges and corners. In addition, results showed that features of the films mightily depend on the initial proportions of Ag-Au alloys.