‘Shaving’ Graphene

Demonstrating the ultimate in “taking a little off the top,” chemists at Rice University have developed a method for etching multilayer graphene by chemically shaving off one layer at a time (Science, DOI: 10.1126/science.1199183). The technique gives researchers the ability to pattern device structures in multilayer graphene “with exquisite resolution and dexterity for complex device and display configurations,” project leader James M. Tour says.

To strip off the single layer of graphene, the chemists coat the material with zinc and then rinse it with dilute hydrochloric acid. The treatment removes the top layer of material, leaving the lower layers intact. The researchers can apply the zinc in any pattern or shape, and they can repeat the process to remove additional layers.

Until now, Tour says, there was no reliable method for stripping off a sheet of graphene. “One could only strip all sheets right down to the substrate,” he says. The technique is not limited to graphene either. Tour’s group demonstrates that it also works to peel off a layer of graphene oxide.

Tour tells C&EN that his group was originally using the zinc-acid process in an attempt to reduce graphene to graphane via hydrogenation. To their surprise, they observed the single-layer stripping instead. “It’s one of those exciting times where nature gives us more than we intended to get,” he says. “That is where science really becomes delightful.”

“Ultimately, the ability to peel just a single layer of graphene from a desired area with such a simple and robust technique is exceedingly useful,” Daniel Gunlycke and Paul E. Sheehan, scientists at the U.S. Naval Research Laboratory, in Washington, D.C., write in a commentary about the work. “Local graphene peeling should become a routine tool for researchers to explore new devices.”