Catalytic role of nickel, palladium, and platinum in the formation of carbon nanoclusters

Carbon clusters were prepared by arc discharge from graphite anodes containing nickel, palladium, and platinum at conditions favoring nanotube production. All three metals led to very little encapsulation of themselves or their compounds into the carbon nanoclusters under the conditions studied. However, the characters of the samples, collected from the cathodic deposits as well as from the soot, were different for the three metal-filled rods. Nickel-filled anode stimulated the growth of single-walled nanotubes and also catalyzed the formation of strings of spherical carbon clusters. The growth mechanism of the strings of spherical clusters is proposed. Platinum-filled anode produced the highest density of nanotubes in the slag. Palladium-filled anode generates the same yield of fullerenes as pure graphite but shifts the ratio of fullerenes by enhancing the yield of C₇₀ and higher-order fullerenes.