Robust SERS substrates with massive nanogaps derived from silver nanocubes self-assembled on massed silver mirror via 1,2-ethanedithiol monolayer as linkage and ultra-thin spacer

• Ag nanocubes were assembled on the massed Ag surface with ultra-thin spacer.
• The NPOM configuration makes Ag nanocubes become hotspots on a large scale.
• The homogeneous distribution of Ag nanocubes renders low standard deviation.
• The SERS substrate shows high sensitivity, reliability and precision.
• It is promising for the application by using the simple Raman apparatus.

Robust SERS substrates with hotspots on a large scale from massive nanogaps can be fabricated by assembling Ag nanocubes on the massed Ag mirror via 1,2-ethanedithiol monolayer as linkage and ultra-thin spacer. X-ray spectroscopy was used to confirm the existence of nanogaps. The plasmonic interaction between Ag nanocubes and the massed Ag mirror was corroborated by UV–Vis spectra. The strength and frequency change of plasmon resonance indicates the electrical field coupling between Ag nanocubes and the massed Ag surface. The 1,2-ethanedithiol spacer prevents the plasmon quench from complete contact between Ag nanocubes and the massed Ag surface, being corroborated by both simulations and SERS results. The SERS results prove the supreme performance of the robust substrate by detecting 10−9 M rhodamine 6G solution with high sensitivity (analytical enhancement factor 2.8 × 108), high reliability (6.6% standard deviation from 20-sites measurements), and high precision (calibration line with 99.9% correlation coefficient).

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