Symmetry-controllable assembly of Au nanooctahedron superlattice membranes for SERS

We present a novel approach to adjust the symmetry of Au octahedral nanocrystals in two-dimensional superlattices. By modifying the content of free polymeric ligands added in the nanocrystal solution, we achieve Au nanocrystal superlattices with tip-on-tip arrangements that significantly enhance the surface-enhanced Raman spectroscopy performance. Adjusting the symmetry of two-dimensional superlattice membranes of Au nanoocthedra was realized by regulating the free polymeric ligands during self-assembly, resulting in tip-on-tip configurations that significantly improve the SERS performance.