Surfactant‐Assisted Symmetry Breaking in Colloidal Gold Nanocrystal Growth

Abstract Colloidal anisotropic gold nanocrystals play a central role in the field of plasmonics owing to their tunable optical activity across a wide spectral range. However, achieving sufficient optical quality for practical implementation requires advanced synthetic protocols yielding gold nanocrystals with the desired morphology and plasmonic properties. This Minireview focuses on a fundamental step during the growth of anisotropic nanocrystals, namely symmetry breaking. In connection with thermodynamic and kinetic control of nanocrystal growth, we discuss the complex interplay between the role of seed morphology and that of surfactants, shape‐directing additives and reducing agents. We revisit some iconic syntheses of anisotropic gold nanoparticles, including nanorods, nanotriangles, and nanobipyramids. Finally, we analyze the use of co‐surfactants as an emerging strategy to disconnect the symmetry breaking event from the anisotropic growth process, overcoming current limitations in the synthesis of anisotropic gold nanocrystals.