Highly reproducible surface-enhanced Raman scattering substrate for detection of phenolic pollutants

The ordering degree of nanostructures is the key to determining the uniformity of surface-enhanced Raman scattering (SERS). However, fabrication of large-area ordered nanostructures remains a challenge, especially with the ultrahigh-density (>10¹⁰ cm^-2). Here, we report a fabrication of large-area ultrahigh-density ordered Ag@Al₂O₃/Ag core-shell nanosphere (NS) arrays with tunable nanostructures. The ultrahigh-density (2.8 × 10¹⁰ cm^-2) ordered NS arrays over a large-area capability (diameter >4.0 cm) enable the uniform SERS signals with the relative standard deviation of less than 5%. The as-fabricated highly reproducible SERS substrate can be applied to detect trace phenolic pollutants in water. This work does not only provide a new route for synthesizing the ultrahigh-density ordered nanostructures, but also create a new class of SERS substrates with high sensitivity and excellent reproducibility.