Carbon nanocapsules and single-layered nanotubes produced with platinum-group metals (Ru, Rh, Pd, Os, Ir, Pt) by arc discharge

Encapsulation of platinum-group metals (Ru, Ph, Pd, Os, Ir, Pt) within carbon nanocapsules and synthesis of single-layered (SL) carbon nanotubes by are evaporation of metal/carbon composites have been studied. Transmission electron microscopy revealed that all the platinum-group metals, forming small particles (10-200 nm in diameter), were encapsulated within multilayered graphitic cages. Particles trapped in the cages were single-domain crystallites in normal metallic phases. Ph, Pd, and Pt showed catalytic activity for growing SL carbon tubes, but the other metals did not. Bundles of dense SL tubes with diameter 1.3-1.7 nm were extruding radially from metal particles for Ph and Pd; the sizes of core particles were 20-30 nm for Rh, and 50-200 nm for Pd. In the case of Pt, one or a few SL tubes (typically 1.3-2.0 nm in diameter and sometimes similar to 3 nm) grew from a tiny particle (similar to 10 nm). (C) 1996 American Institute of Physics.