Graphene is a honeycomb-structured carbon material known for its electronic properties. Despite being only one-atom thick, a layer of graphene is considered one of the strongest materials ever tested.
The material is being studied for use in next generation energy devices such as organic solar cells and ultracapacitors.
The researchers found out that the use of hydrogen is much better than carbon in dictating the shape and size of the graphene grain.
“Hydrogen, which was thought to play a rather passive role, is crucial for graphene growth as well. It contributes to both the activation of adsorbed molecules that initiate the growth of graphene and to the elimination of weak bonds at the grain edges that control the quality of the graphene,” explained Ivan Vlassiouk of O.R.N.L.
The change and size of the graphene domains, as well as the number of layers, change with hydrogen pressure from irregularly shaped incomplete bi-layers to well-defined perfect single layer hexagons.
The researchers created a method to reliably synthesize graphene on a large scale. The fact that their technique allows them to control grain size and boundaries may result in improved functionality of the material in transistors, semiconductors and potentially hundreds of electronic devices.
Until now, grown graphene films were grown by decomposition of carbon-containing gases on a copper foil under high temperatures. The process is also known as the chemical vapor deposition.
This resulted in films which consisted of irregular-shaped graphene grains of different sizes.
This research has a bearing on the different applications of graphene in harvesting renewable energy from the sun.
«Our findings are crucial for developing a method for growing ultra-large-scale single domain graphene that will constitute a major breakthrough toward graphene implementation in real-world devices,» Mr. Vlassiouk said.
Mr. Vlassiouk, a Eugene Wigner Fellow led the O.R.N.L. team, along with Sergei Smirnov, a professor of chemistry at New Mexico State University.
The research was supported by the Department of Energy’s Office of Science, in part through the Fluid Interface Reactions, Structures and Transport Center.
