Introduction
© 2009 ACS
Graphene — an individual layer of carbon atoms arranged in a honeycomb lattice — was first isolated in 2004. It has since become one of the hottest topics in condensed-matter physics and materials science. Cheng Zeng and colleagues1 at the University of Nebraska-Lincoln have now theoretically predicted a new two-dimensional material — B2C graphene.
In B2C graphene the atoms are packed into an array of hexagons and rhombuses, and each carbon atom is bonded to four boron atoms, rather than to three carbon atoms as in graphene. A planar species in which a carbon is bonded to four other atoms may seem peculiar, but it is a concept that was first conceived by Roald Hoffmann and colleagues in 1970, and has since been observed in molecules containing aluminium.
The first-principles calculations also suggest that B2C graphene may be a metal, in contrast to graphene, which is a zero-gap semiconductor (an electronic state precisely between a semiconductor and a metal). But like graphene, the B2C graphene layer can be 'rolled-up' to form a variety of nanotubes, which can be metallic or semiconducting. Nanoribbons of B2C graphene are also predicted and are expected to be uniformly metallic, regardless of their width or edge structure.
