Uniform Bimetallic Nanocrystals by High-Temperature Seed-Mediated Colloidal Synthesis and Their Catalytic Properties for Semiconducting Nanowire Growth

A general procedure to prepare uniform gold-based bimetallic nanocrystals (NCs) is reported. The method relies on a seed-mediated approach in which deposition and in-situ alloying of a second metal (Ag, Pt, Hg, Sn, Cd) onto monodisperse Au seeds are performed at relatively high temperatures, giving access to bimetallic NCs of tunable compositions and properties. The position of the plasmon resonance in the original Au NCs is tunable over a wide range (∼300–520 nm) of the electromagnetic spectrum. We demonstrate the catalytic properties of these monodisperse NCs for growing single-crystalline semiconductor nanowires of uniform, small diameter (∼15–30 nm) via a vapor–liquid–solid (VLS) mechanism at low temperatures. This seeded-mediated approach is not restricted to Au but can be extended to several other combinations, making this procedure a straightforward method to prepare highly monodisperse and controllable multimetallic nanocrystals for optical and catalytic applications.