Transmission electron microscopy of Ru supported on model oxide surfaces

Abstract The shape and structure of small Ru crystallites have been investigated using transmission electron microscopy (TEM). The Ru crystallites were supported on nonporous submicron oxide particles having simple geometric shapes, e.g., spheres, cubes, etc. The use of such model supports considerably facilitates TEM of small metal crystallites. Since the metal is located on the external surface of the oxide particles, it is possible to observe the crystallites in projection through the oxide as well as edge-on. The profile views yield information on metal-oxide interfaces, contact angles, and wetting. We have found the shapes of Ru crystallites to be similar on both silica and magnesia surfaces. While small crystallites look spherical, the larger crystallites have characteristic ellipsoidal shapes. The larger crystallites are faceted and expose the {00.1}, {10.1}, and {10.0} surfaces of ruthenium.