The soot produced as a byproduct of fullerene synthesis by arc-evaporation consists of a microporous carbon with a surface area, after activation with carbon dioxide, of ca. 700 m2 g-'. Here, we investigate the structure of this material, and its appearance after electron irradiation and high-temperature heat treatment, using high-resolution electron microscopy. We show that the heat treatment transforms the new carbon into a structure containing large, tube-like pores, rather than into polycrystalline graphite. This suggests that the arc-evaporated carbon may have a novel, fullerene-related microstructure, and that it may be the precursor for nanotube formation. The discovery that C,, and other fullerenes could be extracted from the carbon soot produced by arc-evaporation of graphite rods' has stimulated enormous interest. Naturally , most of this interest has focused on the fullerenes themselves rather than on the residual soot which remains following fullerene removal. Nevertheless, there are good reasons to believe that this residual material also has a novel microstructure which may be of considerable theoretical and practical interest. In a recent study2 we investigated the properties of the soot following removal of fullerenes and 'activation' in carbon dioxide. We found that the material had a very high internal surface area (ca. 700 m2 g-'), and that it displayed molecular sieving properties indicative of a microporous structure with most of the pores 6 5 8, in diameter. High-resolution electron microscopy (HREM) confirmed that the structure was highly microporous, with an appearance quite similar to that of some conventional high-surface-area carbons. Here, we describe a more detailed programme of studies of the arc-evaporated soot using HREM. We compare the properties of the soot with those of a high-surface-area carbon prepared by pyrolysis of Saran resin, a poly(viny1idene chloride)/poly(vinyl chloride) copolymer. In this way we aim to determine how the fullerene-related soot differs from conventional microporous carbon. Experimental Preparation of Arcevaporated Soot Arc-evaporation of graphite rods was carried out in the standard way for C,, production. Thus, electrolytic grade rods were arced in 150 Torr helium using a dc voltage of 32 V and a current of 180-200 A. Under these conditions ca. 70% of the vaporised carbon deposited onto the walls of the evaporation vessel, while ca. 30% 'distilled' onto the cathodic rod, as shown in Scheme 1. The soot which formed on the walls of the vessel (Cl) was carefully collected and the soluble ful-lerenes were extracted with toluene for three days in a Soxhlet apparatus, after which the solvent was removed under reduced pressure. The residual insoluble soot, C3, was then dried and activated by treatment in a stream of carbon dioxide, with a flow rate of 20 ml min-at 850 "C for ca. 5 h. Under these conditions the reaction C + CO,-, 2CO occurs and after the 5 h period a weight loss of ca. 15% was observed. The final product was a microporous carbon which we des...
