Hydrogen found to be essential to creating better graphene
Graphene, the "wonder material" composed of single-atom-thick carbon sheets, is currently finding its way into a variety of electronic devices including computer chips, capacitors, transistors and batteries, just to name a few. It is typically created using a chemical vapor deposition process, in which carbon-containing gases are made to decompose on a copper foil substrate. The performance of the material may be limited, however, due to the fact that the individual graphene grains in one sheet are not of a consistent size or shape, and are usually larger than a single crystal. That could be about to change, though, as a new production method that utilizes hydrogen gas is promising higher-performance graphene with uniform, single-crystal grains.
The proprietary new process was developed by a team of scientists, led by Ivan Vlassiouk of the U.S. Department of Energy's Oak Ridge National Laboratory, and Sergei Smirnov, a professor of chemistry at New Mexico State University.
"We have shown that, surprisingly, it is not only the carbon source and the substrate that dictate the growth rate, the shape and size of the graphene grain," Vlassiouk said. "We found that 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."
The process is reportedly capable of producing graphene sheets with well-defined, perfectly hexagonal, identical, single-crystal grains. The researchers claim it could lead to the large-scale production of higher-quality graphene, which could in turn result in better-performing electronics.
"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," said Vlassiouk.
The research was recently published in the journal ACS Nano.