Epitaxially grown model catalyst particles of platinum, rhodium, iridium, palladium and rhenium studied by electron microscopy

摘要: In order to obtain oriented thin film model catalysts, small particles of Pt, Rh, Ir, Pd and Re (2–20 nm in size) were grown by high vacuum evaporation on NaCl cleavage faces or situ deposited films at 523–673 K. The covered with a supporting Al2O3 carbon removed from the substrate. High resolution electron microscopy, selected area diffraction weak-beam dark-field imaging applied determine particular morphology, microstructure orientation observed particles. Special attention was paid Rh which appear variety shapes. Ir catalysts consist mainly (001) half octahedra may exhibit truncations corners top. This also dominant shape but addition tetrahedra (011) epitaxy multiply-twinned like decahedra (001), (111) evident. These habits provide definite “initial state” for study changes structure morphology during activating heat treatments necessary induce catalytic activity supported metal films. Although consisted irregularly shaped particles, revealed partial epitaxial alignment both c.p.h. f.c.c. Re.