氢气是生产高质量石墨烯的关键因素

A new approach to growing graphene（石墨烯） greatly reduces problems that have plagued researchers in the past and clears a path to the crystalline form of graphite's use in sophisticated electronic devices of tomorrow. Findings of researchers at the Department of Energy's Oak Ridge¹ National Laboratory demonstrate that hydrogen rather than carbon dictates³ the graphene grain shape and size, according to a team led by ORNL's Ivan Vlassiouk, a Eugene Wigner Fellow, and Sergei Smirnov, a professor of chemistry at New Mexico State University. This research is published in ACS Nano.

"Hydrogen not only initiates⁴ the graphene growth, but controls the graphene shape and size," Vlassiouk said. "In our paper, we have described a method to grow well-defined graphene grains that have perfect hexagonal（六边的） shapes pointing to the faultless single crystal structure."

In the past two years, graphene growth has involved the decomposition⁶（分解，腐烂） of carbon-containing gases such as methane⁷ on a copper⁸ foil under high temperatures, the so-called chemical vapor⁹ deposition¹⁰ method. Little was known about the exact process, but researchers knew they would have to gain a better understanding of the growth mechanism¹¹ before they could produce high-quality graphene films.

Until now, grown graphene films have consisted of irregular- shaped graphene grains of different sizes, which were usually not single crystals.

"We have shown that, surprisingly, it is not only the carbon source and the substrate that dictate² 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 activation¹² of adsorbed molecules¹³ that initiate⁵ the growth of graphene and to the elimination¹⁴ of weak bonds at the grain edges that control the quality of the graphene."

Using their new recipe, Vlassiouk and colleagues have created a way to reliably synthesize（合成，综合） 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 transistors¹⁵, semiconductors¹⁶ and potentially hundreds of electronic devices.

Implications of this research are significant, according to Vlassiouk, who said, "Our findings are crucial for developing a method for growing ultra-large-scale single domain¹⁷ graphene that will constitute a major breakthrough toward graphene implementation¹⁸（实现，履行） in real-world devices."