Tailoring the Shape of Anisotropic Core–Shell Au–Ag Nanoparticles in Dimethyl Sulfoxide

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.