System Bits: July 8

Carbon nanotubes “unzipped” into graphene nanoribbons by a chemical process invented at Rice University are finding use in all kinds of projects, but Rice scientists have now found a chemical-free way to unzip them.

A Rice materials scientist discovered that nanotubes that hit a target end first turn into mostly ragged clumps of atoms, but nanotubes that happen to broadside the target unzip into handy ribbons that can be used in composite materials for strength and applications that take advantage of their desirable electrical properties.

The result was a surprise to the researchers who said that until now, they knew they could use mechanical forces to shorten and cut carbon nanotubes and this was the first time they have showed carbon nanotubes can be unzipped using mechanical forces.

The process they developed eliminates the need to clean chemical residues from nanoribbons produced through current techniques meaning that one-step, chemical-free, clean and high-quality graphene nanoribbons can be produced using this method, which are potential candidates for next-generation electronic materials.

Molecular simulations and electron microscope images show what happens to a carbon nanotube when the end of it strikes a target directly at about 15,000 miles per hour. Rice University researchers found the nanotubes split into useful nanoribbons. (Source: Ajayan Group/Rice University)