Bright spark creates new way to mass-produce graphene

Forget chemicals, catalysts and expensive machinery – a team of physicists at Kansas State University (KSU) has discovered a way to mass-produce graphene using just three simple ingredients: hydrocarbon gas, oxygen and a spark plug.

Their method is simple. Fill a chamber with acetylene or ethylene gas and oxygen; use a vehicle spark plug to create a contained detonation; collect the graphene that forms afterward.

Chris Sorensen, professor of physics at KSU, is the lead inventor of this novel process, which was recently granted a patent. Other KSU researchers involved include Arjun Nepal, a postdoctoral researcher and instructor of physics, and Gajendra Prasad Singh, a former visiting scientist.

"We have discovered a viable process to make graphene," Sorensen said. "Our process has many positive properties, from the economic feasibility, the possibility for large-scale production and the lack of nasty chemicals. What might be the best property of all is that the energy required to make a gram of graphene through our process is much less than other processes because all it takes is a single spark."

Graphene is a single atom-thick sheet of hexagonally-coordinated carbon atoms, which makes it the world's thinnest material. Since graphene was first isolated in 2004, scientists have found that it possesses valuable physical and electronic properties with many possible applications, including more efficient rechargeable batteries and better electronics.

For Sorensen's research team, the serendipitous path to creating graphene started when they were developing and patenting carbon soot aerosol gels. They created the gels by filling a 17L aluminum chamber with acetylene gas and oxygen, and then using a spark plug to produce a detonation in the chamber. The soot from the detonation formed aerosol gels that looked like "black angel food cake", Sorensen said.

But on further analysis, the researchers found that the aerosol gel was more than just a lookalike for dark angel food cake – it was graphene. "We made graphene by serendipity," Sorensen said. "We didn't plan on making graphene. We planned on making the aerosol gel and we got lucky."

Unlike other methods for creating graphene, Sorensen's method is simple, efficient, low-cost and scalable for industry. These other methods include ‘cooking’ the mineral graphite with chemicals – such as sulfuric acid, sodium nitrate, potassium permanganate or hydrazine – for a long time at precisely prescribed temperatures, and heating hydrocarbons to 1000°C in the presence of catalysts.

Such methods are energy intensive – and even dangerous – and have low yields, while Sorensen and his team's method makes larger quantities with minimal energy and no dangerous chemicals. "The real charm of our experiment is that we can produce graphene in the quantity of grams rather than milligrams," Nepal said.

The research team is now working to improve the quality of the graphene and to scale the laboratory process to an industrial level. To this end, they are upgrading some of the equipment to make it easier to get graphene from the chamber quickly: seconds – rather than minutes – after the detonation. Accessing the graphene more quickly could improve the quality of the material, Sorensen said.

This story is adapted from material from Kansas State University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.