Shape
and size control of metal
nanoparticles at the nanoscale is a crucial step in the development
of diverse applications ranging from catalysis to plasmonics and surface-enhanced
Raman spectroscopy (SERS). For the seed-mediated growth of nanocrystals,
it is well established that the final morphology is dictated not only
by the crystallinity of the seed but also by surfactant and additives.
However, the systematic study of the impact and the fate of these
additives to elucidate the growth mechanism remains challenging. Here,
we show that the addition of dimethyl sulfoxide (DMSO) for the silver
growth on gold nanorod seeds allows tailoring the shape of core–shell
Au@Ag from truncated cuboids to octahedra. The combination of surface
enhanced Raman scattering and X-ray photoelectron spectroscopies revealed
the key role played by DMSO and its fate upon silver reduction.