Ordered plasmonic nanoparticle arrays are highly desirable
for
optical sensing as they provide uniformly distributed plasmonic hotspots
due to their periodic order and near-field coupling. Anisotropic-shaped
bimetallic nanoparticles are of particular interest, as their hybridized
plasmonic modes enable precise tuning of plasmonic resonance and optical
responses. However, the controlled assembly of large-scale arrays
of bimetallic nanoparticles with uniformly distributed hotspots remains
a challenge. In this study, we present a highly robust and reproducible
method for creating large-area vertically aligned arrays of bimetallic
Au–Ag nanorods by epitaxially growing Ag over preassembled
Au nanorods. Structural characterization using electron microscopy
and X-ray photoelectron spectroscopy confirms the formation of a uniform
thin layer of Ag, creating a bimetallic Au–Ag nanorod array.
We also demonstrate the efficacy of the designed nanoarrays for surface-enhanced
Raman scattering (SERS) spectroscopy. Our experimental and computational
studies show considerably enhanced optical responses of bimetallic
Au–Ag nanorods compared to their monometallic counterparts.
The scalability, cost-effectiveness, and reproducibility of this method
make it a versatile platform for creating various structures by varying
guest nanoparticles in suspensions with broad applications in biomedical
research, food safety surveillance, and environmental monitoring.