Self-Assembly of Faceted Gold Nanocrystals for Surface-Enhanced Raman Scattering Application

In this work, self-assembly monolayers of faceted gold nanocrystals were employed as surface-enhanced Raman scattering (SERS) substrates for the examination of facet-dependent SERS performance. In particular, cubes, concave cubes, octahedra, and rhombic dodecahedra with three sizes have been synthesized via a seed-mediated growth method. All 12 samples with high purity and size uniformity were assembled into densely arranged monolayers by a robust liquid/liquid interface self-assembly technique, and their localized surface plasmon resonance properties were comparatively investigated. Furthermore, the SERS activity of these monolayers on a Si wafer was analyzed, and rhombic dodecahedra were found to possess the strongest enhancement as excellent SERS substrates. Meanwhile, the simulation of electromagnetic field distribution based on a diverse faceted gold nanoparticle array was performed by FDTD solutions software, which supports our SERS behavior results. Finally, rhombic dodecahedral gold nanocrystals were effectively applied to the analysis of two pesticides in orange juice. As a result, rhombic dodecahedra are expected to serve as highly sensitive SERS substrates for the real-world detection of a variety of molecules.