Synthesis and Structural Characterization of a Highly Ordered Mesoporous Pt−Ru Alloy via “Evaporation-Mediated Direct Templating”

Highly ordered 2D-hexagonal mesoporous Pt−Ru alloy particles were deposited by an electrochemical process after a lyotropic liquid crystalline (LLC) film including both Pt and Ru species was prepared on a conductive substrate from a diluted surfactant solution by casting. We have determined the alloy state by using high-resolution scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopic (EDS) mapping, and X-ray photoelectron spectroscopy (XPS). The HR-SEM images show that the porous nanostructures are formed over the entire area on the external surface of each particle. The TEM images prove that the pore wall is composed of connected nanoparticles of ca. 3 nm in size and that the lattice fringes assigned to a fcc structure are randomly oriented. The EDS mapping shows both elements of Pt and Ru are well distributed within the pore wall. From the XPS data, Ru atoms in the alloy are thought to basically be in the zerovalent metallic state, Ru(0). These results indicate the formation of mesoporous intermetallic Pt−Ru alloys. The structural information on the mesoporous alloys should be very useful for development of mesoporous metals toward advanced nanomaterials.