Organized Surfaces of Highly Faceted Single-Crystal Palladium Structures Seeded by Sacrificial Templates

The templated synthesis of periodic arrays of highly faceted single-crystal structures of palladium is described. The devised route confines an array of sacrificial gold templates between a palladium foil and a single-crystal oxide substrate. At elevated temperatures, the gold templates are annihilated and replaced with palladium structures situated at the precise locations formerly occupied by gold. The assembly process relies on the concurrent sublimation of palladium and gold, which results in the complete transfer of the templated gold from the substrate to the foil but not before the templates act as heterogeneous nucleation sites for palladium adatoms arriving to the substrate surface. The so-formed palladium structures take on the equilibrium Wulff shape expected for elements with a face-centered cubic crystal structure, where the shape and crystallographic alignment of the arrayed structures is promoted through a heteroepitaxial relationship with the underlying substrate. The assembled structures provide an excellent platform for advancing applications reliant on the unique hydrogen storage, catalytic, and plasmonic properties of palladium.