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Graphitic Carbon Produced at Very Low Temperatures During the Synthesis of Iron Oxide Nanoparticles

Graphitic carbon - structural forms of the element that are constructed exclusively from carbon atoms having trigonal planar coordination - is ordinarily produced under drastic physical and conditions, typically at temperatures in excess of 500° C. Columbia MRSEC scientists have uncovered a process by which this form of matter can assemble at temperatures as low as 110° C. During their development of a low-temperature synthesis of nanocrystals of iron oxides, Drs. Erich Walter, Louis Brus and Michael Steigerwald found that bis(cyclooctatetraene)iron, Fe(C8H8)2, an arcane organometallic compound, when exposed to dimethylsulfoxide, a chemically mild source of oxygen, yields not only the desired nanoparticulate Fe3O4 but also graphitic carbon. The carbon occurs as single sheets (graphene, Figure A), and in tubes (multi-walled carbon nanotubes, MWCNTs, Figure B).

Graphene and carbon nanotubes are remarkable materials that will be used in electronic- and energy-related science and engineering, but this applicability has been stymied until now by the scarcity of controllable methods of fabrication of specific types, sizes, and shapes of these apparently simple chemicals. Low-temperature chemical reactions such as this process under development at Columbia are particularly valuable because they are more controllable than the higher-temperature analogs. By using different chemical feedstock and appropriate auxiliary ligands, the Columbia MRSEC researchers believe they will be able to direct this catalytic process rationally to produce sheets or tubes of the desired sizes and shapes.

For more, see J. Am. Chem. Soc., 49, 15590-1 (2006) or contact: Michael Steigerwald.