For orderly graphene sheets, just add Hydrogen

Researchers have known for some time that the quality of graphene produced by vapour deposition depends on a number of factors: the carbon source and the substrate material being major players.

However, scientists at the US Department of Energy’s National Laboratory in Oak Ridge have found that hydrogen plays a much more active role in the formation of the material than previously thought.

According to their paper, published in ACS Nano the hydrogen both "initiates the graphene growth…and controls its shape and size."

Ivan Vlassiouk, a Eugene Wigner Fellow says, in the press release: "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."

Making smooth sheets of graphene is not as simple as one would hope, and in the real world, it rarely resembles the nice orderly chicken wire grid you see illustrating articles all over the web. This is a problem because irregularities in graphene sheets affect its properties, making it less predictable harder to put into use.

The discovery that hydrogen can produce more regular crystals of the wonder material gives scientists working with the material ever finer degrees of control over its properties, leading to better kit, sooner.