Supported Core/Shell Bimetallic Nanoparticles Synthesis by Atomic Layer Deposition

A continuing goal in catalysis research is to engineer the composition and structure of noble metal nanomaterials in order to precisely tune their catalytic activity. Herein, we present proof-of-concept results on the synthesis of supported bimetallic core/shell nanoparticles entirely by atomic layer deposition (ALD). ALD is a novel and scalable method, which can be used to prepare noble-metal catalysts on high surface area support materials. Two properties of ALD of noble metals, namely the Volmer-Weber growth and surface-selectivity, are exploited to decouple primary island growth from subsequent selective shell growth. This concept is applied to synthesize highly dispersed Pd/Pt and Pt/Pd nanoparticles. In-depth characterization of the nanoparticles provides evidence for the core/shell morphology and for the narrow size distribution. The self-limiting nature of the ALD process allows for independent control of the core and shell dimensions, opening up unique possibilities for precise engineering of metallic nanoparticle properties.