Dewetted nanostructures of gold, silver, copper, and palladium with enhanced faceting

At the foundation of nanoscience and nanotechnology is the ability to shape-engineer nanometric objects so as to exert control over their physical and chemical properties. Architectural control is achieved by manipulating thermodynamic and kinetic factors that are able to guide reactions along pathways that lead to the formation or elimination of particular crystal facets. While the dewetting of ultrathin metal films provides a straightforward method for generating substrate-based metallic nanostructures, the ability to shape-engineer these structures is limited to such an extent that even the formation of highly faceted equiaxed structures often proves challenging. This, however, is not the case for colloidal syntheses where the exquisite chemical controls and synthetic ease offered by liquid-phase chemistry has led to the generation of a diverse library of nanostructure architectures. Here, it is demonstrated that the faceting of dewetted structures of gold, silver, copper, and palladium can be enhanced by subjecting them to a liquid-phase chemical environment in which metal ions are reduced to a neutral state and deposited on the nanostructure surface in manner that leads to facet formation. The faceting procedure, which can be carried out in minutes, is also shown to be amenable to a templated dewetting approach in which lithographically-defined metal discs formed in an array each agglomerate to form a single nanostructure. The work has the potential to increase the functionality of dewetted nanostructures by enabling facet-dependent chemical reactivity and plasmonic hot spots.