Penn State professor Thomas E. Mallouk is $10 richer and the world is one step closer to realizing the dream of mass-producing high grade synthetic graphene, a “wonder material” only one atom thick and 200 times stronger than steel. Mallouk’s Penn State team came up with the new material after he bet research associate Nina Kovtyukhova $100 against $10 that she could come up with a new way to split a nanoscale sheet of graphene away from graphite.
Why Synthetic Graphene?
We’ve been making quite a fuss over graphene here at CleanTechnica since way back when. Its high strength, light weight, and unique electronic properties make it a perfect match for next-generation solar cells, EV batteries, wind turbines and you name it.
Graphene consists of a lattice of carbon atoms, which also means that it could be incredibly cheap. The problem is that sheets of graphene don’t exist in nature, so you have to make them. Also keep in mind that diamonds are made of carbon and they don’t come cheap, either.
One way to do it is to “grow” a layer of graphene onto a substrate, and then peel the substrate off.
That method harkens back to the discovery of graphene in 2004, when Konstantin Novoselov and Andre Geim bagged a Nobel prize after literally peeling a layer of graphene off from a chunk of graphite using sticky tape. The problem is that the multi-step process is a cost multiplier.
You could also whip up some synthetic graphene flakes using a kitchen blender and some other secret sauce, or you could put some dry ice and steel balls (don’t ask) together in a canister, but the result is a batch of graphene containing some good and some not-so-good samples.
Pristine Synthetic Graphene From a 150-Year-Old Recipe
The new Penn State synthetic graphene method is of particular interest because of its relative simplicity and its potential for consistently producing high-quality sheets of graphene on an industrial scale.
Rather than growing, imprinting, or whipping graphene into being, the process is called intercalation.
As the word suggests, intercalation involves placing “guest” molecules or ions into graphite, forcing it to split apart in sheets.
Here’s where that $10 bet comes in. Intercalation is nothing new, and according to the Penn State team an intercalation method for graphite has been around since 1841.
If you’re wondering why graphene wasn’t discovered in 1841, that’s because the intercalation of graphite requires an oxidizing agent, which wreaks havoc with the very properties that give graphene its special powers.
So, for about 150 years intercalation of graphite has been wandering down a side track. One of those in pursuit just so happens to be a research associate in Mallouk’s lab, and if you guessed Nina Kovtyukhova you would be correct. In 1999 she developed a new oxidation-based method for intercalating graphite that is apparently one of the most widely used today.
Whilst Mallouk and Kovtyukhova were fooling around with some intercalation on various materials, they discovered that boron nitride could be split without an oxidizer.
That must have caused a ripple of excitement in the lab because boron nitride has been dubbed “white graphene” on account of the properties it shares with graphene. Nevertheless, all the literature called for an oxidizing agent when you’re intercalating graphite, so as Mallouk tells it the idea of trying oxidizer-free intercalation on graphite was a nonstarter until…
Finally, we made a bet, and to make it interesting I gave her odds. If the reaction didn’t work I would owe her $100, and if it did she would owe me $10. I have the ten dollar bill on my wall with a nice Post-it note from Nina complimenting my chemical intuition.
An Acid Bath For Graphene
Okay you’ve had your fun, now let’s get back to work. The research team, which included Japan’s Research Center for Exotic Nanocarbons at Shinshu University, published their discovery online at the journal Nature under the title “Non-oxidative intercalation and exfoliation of graphite by Brønsted acids.”
Brønsted refers to a group of acids including phosphoric, sulfuric, dichloroacetic and alkylsulfonic acids, so as you can imagine the process is still pretty nasty.
However, an analysis of the first stage of the process confirms that the graphene layers remain intact. They can then be split off into monolayer and multilayer graphene sheets in a solution of dimethylformamide, which sounds fancy but it’s just longspeak for DMF, a common solvent used in manufacturing plastics, pharmaceuticals, pesticides, and a lot of other stuff.
So for now we still have these graphene sheets sitting in a bath of DMF, but it’s a start. Among other things the research team is already working on ways to get the reaction moving along at a commercial-scale rate.
They better hurry it up because the last time we checked, a Polish startup backed by the global metals company KGHM was thisclose to commercial production of graphene using a method based on a crystalline-on-crystalline technique.
Source: CleanTechnica. Reproduced with permission.