A porous Au–Ag hybrid nanoparticle array with broadband absorption and high-density hotspots for stable SERS analysis

Abstract

Constructing high-density hotspots is of crucial importance in surface enhanced Raman scattering (SERS). In this paper, we present a large-area and broadband porous Au–Ag hybrid nanoparticle array which was fabricated by an ultra-thin alumina mask (UTAM) technique incorporated with annealing and galvanic replacement techniques. Experimental results and numerical simulations demonstrated that the porous Au–Ag hybrid nanoparticle array possessed enormous hotspots for high sensitivity, uniformity, and stability in SERS analysis. A large Raman enhancement factor of 2.2 × 10⁷ was achieved with a relative standard deviation (RSD) of 7.7%, leading to excellent reliability for Raman detection. Furthermore, this novel substrate exhibited a long shelf time in an ambient environment and promising practical applications in many SERS-based quantitative analytical and biomedical sensing techniques.