The structure of negatively curved spongy carbon

This work reports on the production and characterization of a novel form of nanostructured carbon consisting of three-dimensional, fully connected Sp(2) networks. This form of carbon is characterized by interconnected thin layers forming a spongy structure with meso- and macroporosity. The spongy carbon is produced by a pulsed microplasma cluster source in the presence of a metal-organic catalyst and it can be deposited as a film by supersonic cluster beam deposition (SCBD). Unlike fullerenes, nanotubes and graphite, which consist of zero-, one- or two-dimensional covalent objects held together by van der Waals' forces, this novel structure consists of a robust, multiply connected graphene sheet which is fully covalent in three dimensions. Theoretical analysis indicates that such carbon sponges apparently grow as minimal surfaces and have the long-sought topological structure of random schwarzites. (C) 2003 Elsevier Science B.V. All rights reserved.