Gold Nanopolyhedron-Based Superlattice Sheets as Flexible Surface-Enhanced Raman Scattering Sensors for Detection of 4-Aminothiophenol

The self-assembly of plasmonic building blocks into superlattices has emerged as a promising route to fabricate metamaterials with customizable nanoscale architecture and collective properties. However, self-assembly of such plasmonic superlattice has proven challenging, owing to the low packing fraction, complex interparticle forces, and local heterogeneity. Besides, the conventional assembly of small nanoparticles usually exhibits localized defects and uncontrollable electromagnetic field distribution, limiting its functionality for real-world application. Here, we report on the self-assembly of multifacet gold nanopolyhedron (AuNPH) into high-quality giant plasmonic superlattice sheets. This bottom-up method involves soft ligand-balanced crystallization of AuNPHs in conjunction with drying-mediated self-assembly. Such AuNPHs superlattice sheets exhibit macroscopic surface area while maintaining a highly ordered nanoscopic structure. We also demonstrate by both experiment and theoretical simulation that the surface-plasmon-induced hotspots are uniformly distributed across the sheet surface, facilitating its application as flexible surface-enhanced Raman scattering (SERS) sensors for detection of 4-aminothiophenol. The Raman enhancement factor (EF) of this flexible SERS sensor can reach 1.7 × 106 with a detection limit reaching the nanomolar scale. Moreover, the Raman signals exhibited high homogeneity across the superlattice sheets with a low relative standard deviation of 4.3%. Such flexible AuNPHs superlattice sheets can be applied as nonconventional SERS platforms with well-defined customizability, suggesting a robust and efficient avenue for real-world applications in high-sensitive inspection of drugs, explosives, and environmental pollutants.