Regiospecific growth of Au on a concave PtZn nanocube forming an Au-PtZn surface mosaic nanocube and an Au-PtZn octapod

Regioselective growth of a heterophase on facet-controlled nanocrystals is an indispensable step towards generation of geometrically well-defined heteronanoarchitectures. The growth of a heterophase usually occurs on the most unstable surface features of a nanoparticle, such as vertices and edges, and therefore the ability to control the surface energy of facet-controlled nanocrystals is crucial for the rational synthesis of nanoarchitectures. It is, however, not easy to attain the ability to regioselectively grow a heterophase on a facet-controlled nanocrystal. Herein we introduce a simple strategy to pinpoint the site of heterophase growth on the surface of a faceted nanocrystal by controlling the concentration of surface-stabilizing moieties. Specifically, we show the regioselective growth of Au on a PtZn concave nanocube, covered with surface-bound CO moieties, forming two completely different Au-PtZn heteronanostructures of a filled-concave Au-PtZn surface mosaic nanocube and a vertex-covered Au-PtZn octapod. We also show their application in surface-enhanced Raman scattering (SERS)-based detection of small molecules.