Superlattice assembly strategy of small noble metal nanoparticles for surface-enhanced Raman scattering

Abstract

The self-assembly of noble metal nanoparticles into periodic structures has been a theme of great interest for surface-enhanced Raman scattering (SERS) and use in functional devices. However, small nanoparticle self-assembly faces numerous challenges in tunability, referring to controlling their structural properties like structure, gaps, and arrangement. These issues highlight the need for further research and development to enhance the tunability and stability of self-assembled small nanoparticles. Here, we report a general centimeter-scale superlattice assembly strategy for noble metal nanoparticles less than 15 nm in size. Not only is this monolayer superlattice assembly generally applicable to different kinds and sizes of noble metal nanoparticles, but also, the crystal plane spacing can also be quickly and conveniently controlled by changing the ethanol concentration. SERS results reveal that optimized superlattice membranes of noble metal nanoparticles possess high detection sensitivity and ordered hot spots. Therefore, our strategy offers prospects for high-performance SERS substrates based on small noble metal nanoparticle superlattices.

Self-assembly of small nanoparticles is difficult to control and the resultant structures have weak stability. Here, a general centimeter-scale superlattice assembly strategy for noble metal nanoparticles of less than 15 nm is used to yield stable hexagonal close-packed monolayers.