Facile Preparation of Au–Ag Composite Nanostructure for High-Sensitive and Uniform Surface-Enhanced Raman Spectroscopy

Abstract

Preparation of a high-sensitive and uniform surface-enhanced Raman spectroscopy (SERS) active substrate structure usually faces complex processes and high costs. Here, porous Au–Ag composite nanostructures that are conventional fabricated by the deposition of a multilayer Au–Ag, annealing, and dealloying process are proposed for high-performance SERS. By annealing at a suitable temperature, nanopores could be firmly distributed on the surface, which serves as hot spots. The electric field distribution was also performed by the finite difference time domain. The experiment results exhibited excellent uniformity and high sensitivity of SERS detection. The enhancement factor of the R6G molecules detected by the SERS substrate reached 1.37 × 107, and the relative standard deviation was as low as 4.9%. The minimum detection concentration of R6G molecules by the Au–Ag composite nanostructures with bottom Au mirror could reach 10−13 M. The proposed Au–Ag composite nanostructures and the fabrication process have great potential in preparation of a high-sensitive and uniform SERS substrate.