Turning Nanotubes Into Nanoribbons

A chemical method can unzip multiwalled carbon nanotubes (MWNTs) along their lengths to produce ribbonlike strips of graphene, according to researchers in Mexico.

These graphene nanoribbons, which are elongated one-atom-thick strips of carbon, exhibit tantalizing mechanical and electronic properties. The materials are under study for applications ranging from hydrogen storage and battery electrodes to polymer nanocomposites and sensors.

Abraham G. Cano-Márquez, Fernando J. Rodríguez-Macías, and Yadira I. Vega-Cantú, all of the Institute for Scientific & Technological Research, in San Luis Potosi, and coworkers report that treating MWNTs with lithium and ammonia results in the insertion of ammonia-solvated lithium ions between the nanotubes' concentric graphene sheets. That step ruptures the multiwalled structures by prying apart the layers, which are further separated by way of hydrochloric acid and heat treatments (Nano Lett. 2009, 9, 1527).

Compared with other procedures for forming graphene nanoribbons, the new method, together with other recently reported nanotube "unzipping" methods (C&EN, April 20, page 7), offers a potentially simpler, less expensive, and more adaptable route to making large quantities of the material.