In the future, single layers of graphene could be used as electrodes for solar cells, as the anode electrode material in lithium batteries, or as efficient zero-band-gap semiconductors.
But research into graphene sheets has been restricted due to the difficulty of creating single-layer samples for use in experiments. Now, however, researchers from UCLA’s California NanoSystems Institute (CNSI) claimed to have developed a method that can produce graphene sheets in large quantities.
Led by Yang Yang, a professor of materials science and engineering at the UCLA Henry Samueli School of Engineering, and Richard Kaner, a UCLA professor of chemistry and biochemistry, have developed a means of placing graphite oxide paper in a solution of pure hydrazine, which then reduced the graphite oxide paper into single-layer graphene.
Such methods have been studied by others, but this is claimed to be the first reported instance where hydrazine has been used as the solvent.
The graphene produced from the hydrazine solution is also a more efficient electrical conductor. Field-effect devices display output currents three orders of magnitude higher than previously reported using chemically-produced graphene.
The hydrazine process also preserves the integrity of the sheets, while producing the largest-area graphene sheet yet reported – 20 micrometres by 40 micrometres.
Two overlapping images of the same graphene sheet produced by hydrazine reduction: the top image was produced using atomic force microscopy, while the bottom was produced with scanning electron microscopy