The coverage of the graphene sheets can be controlled by altering the concentration and composition of the hydrazine solution. This hydrazine method also preserves the integrity of the sheets, producing the largest-area graphene sheet yet reported, 20 micrometers by 40 micrometers. A micrometer is one-millionth of a meter, while a nanometer is one billionth of a meter.
"These graphene sheets are by far the largest produced, and the method allows great control over deposition," Allen said. "Chemically converted graphene can now be studied in depth through a variety of electronic tests and microscopic techniques not previously possible."
"Interdisciplinary research of this sort is a benefit of collaborative institutes like the CNSI," said Kaner, who is also an associate director of the CNSI. "Graphene is a cutting-edge nanomaterial and one which has great potential to revolutionize electronics and many other fields."
There are two methods currently used for graphene production the drawing method and the reduction method, each with its own drawbacks. In the drawing method, layers are peeled off of graphite crystals until one is produced that is only one-atom thick. When likely graphene suspects are identified from the peeled layers, they must be extensively studied to conclusively prove their identity. In the reduction method, silicon carbide is heated to high temperatures (1100 C) to reduce it to graphene. This process produces a small sample size and is unlikely to be compatible with fabrication techniques for most electronic applications.
"This technology (hydrazine reduction) utilizes a true solution process for graphene, which can dramatically simplify preparing electronic devices," said Yang, who is also faculty director of the Nano Renewable Energy Center at th
|Contact: Mike Rodewald|
University of California - Los Angeles