Optical and Structural Properties of Cuprous Oxide Shell Coated Gold Nanoprisms

Cuprous oxide nanoparticles can be prepared with a great morphological control, and their composites with gold nanostructures are intensively studied owing to their catalytic performance. In this study, cuprous oxide shell growth on nanosized prism‐shaped gold nanoparticles is investigated, where the core‐particle morphology does not match the prototypical cubic or octahedral symmetry of the embedding cuprous oxide particle. It is shown that different shell morphology is obtained depending on the reducing agent used for the shell deposition. Strong reducing agent (hydrazine) leads to a multi‐slab‐like coating with smooth facets, while under milder conditions (hydroxylamine) a multi‐grain coating is obtained. Successful realization of time‐dependent spectroscopic and structural investigations indicate that in this latter case cuprous oxide shell growth is initiated site‐selectively, namely in the highly curved regions of the particle, with a higher growth rate around the tips of the nanoprisms. This is supported by correlative single‐nanoparticle spectroscopy/scanning electron microscopy measurements, that allow to establish the connection between the optical properties and the structure of these plasmonic/semiconductor core/shell nanoparticles.