Shape-controlled synthesis of metal nanostructures: The case of palladium

This article features shape-controlled synthesis of Pd nanostructures. Similar to the Ag system, both the crystallinity of seeds and the growth rates of different crystallographic facets play a vital role in determining the final shape of a resultant nanostructure. We specifically discuss how the reduction rate can be controlled to maneuver the crystallinity (i.e., single-crystal, single twinned, and multiple twinned) of seeds in the nucleation stage. The distribution of multiple twinned and single-crystal seeds can be further manipulated by employing oxidative etching. As the seed grows into a nanocrystal, the growth rates of different facets (e.g., {111} versus (100}) can be altered with capping agents to control the final shape. The ability to generate Pd nanostructures with a variety of geometrical shapes provides a great opportunity to systematically evaluate their electrical, plasmonic, and catalytic properties, as well as to fully explore their applications.