Nano Lett. doi:10.1021/nl1024744 (2010)

In order for single-atom-thick sheets of carbon, or graphene, to be used in sensors, transistors and other devices, reactive molecules must be attached to them so that the sheets can be chemically bonded to other materials. Mingdi Yan at Portland State University in Oregon and her colleagues report a simple way to do this.

They created three variants of perfluorophenylazide, a compound that reacts with graphene's carbon–carbon bonds when heated or illuminated with a mercury lamp. Each variant carried a different molecular group. By mixing each variant individually with a solution of graphene flakes, the team attached a specific molecule to the graphene, preparing the carbon sheet for further chemical bonding.

Previous methods were less controlled, so attached a variety of molecules to graphene at varying densities.