GRAPHITIC STRUCTURE AND SURFACE CHEMICAL ACTIVITY OF NANOSIZE CARBON SPHERES

Monodispersed nanosize carbon spheres have recently been synthesized u sing a mixed-valent oxide-catalytic carbonization (MVOCC) process. In this paper, a high surface porosity of carbon spheres produced by an i nteraction with WO3 is reported. The interaction mechanism is due to t he reduction of WO3 to W driven by an internal Auger decay process und er the stimulation of a high-energy electron beam in a transmission el ectron microscope; combination of the desorbed O with C results in the loss of local carbon species. This process occurs only for the atoms located at the surface and surface diffusion plays a dominant role. Cl osed shell ''onion-like'' concentric fullerenes have been observed, wi th a C-60 molecule at the center. It is suggested that W atom(s) may a lso be trapped within the C-60 cage. The spiral growth model proposed for the growth of large fullerenes and carbon spheres has been directl y proved experimentally. High-resolution electron images suggest the p resence of single-shell toroidal fullerenes. (C) 1997 Elsevier Science Ltd.