Individually Silica-Embedded Gold Nanorod Superlattice for High Thermal and Solvent Stability and Recyclable SERS Application

A facile method to fabricate 2D hexagonal monolayer superlattices of gold nanorods (GNRs) individually embedded in silica matrix on a substrate is developed. In this method, the cetyltrimethylammonium bromide (CTAB) bilayer-coated GNRs are self-assembled into a hexagonally packed monolayer superlattice on the substrate by slow evaporation in the presence of silica precursors in the solution at a highly acidic condition. The GNR superlattices fabricated by this method show excellent structural stability at high temperature as high as 500 °C and in solvents of a wide range of polarities including water, ethanol, toluene, and cyclohexane. The structural stability makes the GNR superlattices highly reusable surface-enhanced Raman scattering (SERS)-active substrates for sensitive molecular detection, well-maintaining the SERS intensity over 10 cycles.