Controlled nanoporous Pt morphologies by varying deposition parameters

We synthesize nanoporous platinum (np-Pt) through electrochemical dealloying in aqueous HF from cosputtered ${\text{Pt}}_x{\text{Si}}_{1-x}$ amorphous films for different initial composition and sputter bias conditions. We demonstrate that, in addition to the expected isotropic open cell np-Pt foam, anisotropic (columnar and Voronoi) np-Pt is obtained. There are two levels of anisotropy: on the micron scale, 100 nm columns or $1\mu \text{m}$ Voronoi polygons form. Inside the columnar and Voronoi hyperstructures, the ligaments and pores are anisotropic ranging from 5 to 25 nm. The ligament diameter and grain size is 5 nm for all reported structures. A processing-structure map is developed that correlate np-Pt structures to processing conditions.