Flash graphene production in action. Image: Jeff Fitlow/Rice University
Instead of putting your food waste in the bin, it could now be used to create graphene as quick as a flash.
Attempting to reduce the mountains of food waste that we accumulate each year, researchers from Rice University have revealed a new process that could also see a massive reduction in the environmental impact of concrete and other building materials. It involves creating valuable graphene flakes from bulk quantities of just about any source of carbon.
This ‘flash graphene’ technique is both quick and cheap, giving us the ability to convert a ton of coal, food waste or plastic into graphene for a fraction of the cost used by other bulk graphene-producing methods.
“This is a big deal,” said James Tour, who led the new process’s development. “The world throws out 30pc to 40pc of all food because it goes bad, and plastic waste is of worldwide concern. We’ve already proven that any solid carbon-based matter, including mixed plastic waste and rubber tires, can be turned into graphene.”
Publishing their findings to Nature, the researchers said flash graphene is made in 10 milliseconds by heating carbon-containing materials to almost 2,800 degrees Celsius. While any source of carbon can be used, food waste, plastic waste, petroleum coke, coal, wood clippings and biochar are seen as prime candidates.
“With the present commercial price of graphene being $67,000 to $200,000 per tonne, the prospects for this process look superb,” Tour said.
As little as 0.1pc of flash graphene in cement used to bind concrete could lessen its environmental impact by a third. This would be a significant saving given that cement reportedly emits as much as 8pc of human-made CO2 each year.
‘It’s a win-win environmental scenario’
“Essentially, we’re trapping greenhouse gases like CO2 and methane that waste food would have emitted in landfills,” Tour said. “We are converting those carbons into graphene and adding that graphene to concrete, thereby lowering the amount of CO2 generated in concrete manufacture. It’s a win-win environmental scenario using graphene.”
The resulting material produces something called ‘turbostratic’ graphene, with misaligned layers that are easy to separate. This type of graphene is much easier to work with because the adhesion between layers is much lower.
Also, the process produces very little excess heat. “You can put your finger right on the container a few seconds afterwards,” Tour said. “And keep in mind this is almost three times hotter than the chemical vapour deposition furnaces we formerly used to make graphene, but in the flash process the heat is concentrated in the carbon material and none in a surrounding reactor.”
Within the next two years, Tour and the other researchers hope to produce 1kg of the ‘wonder material’ as part of a project that will create it from converted coal.
