A new process turns bulk quantities of just about any carbon source into valuable graphene flakes. The “flash graphene” process can convert a ton of coal, food waste, or plastic into graphene for a fraction of the cost used by other bulk graphene-producing methods.
Flash graphene is made in 10 milliseconds by heating carbon-containing materials to 3,000 Kelvin (about 5,000 °F). The source material can be nearly anything with carbon content. Food waste, plastic waste, petroleum coke, coal, wood clippings, and biochar are prime candidates. A concentration of as little as 0.1% of flash graphene in the cement used to bind concrete could lessen its massive environmental impact by a third. The process essentially traps greenhouse gases like carbon dioxide and methane that waste food would have emitted in landfills and converts those carbons into graphene. Adding that graphene to concrete lowers the amount of carbon dioxide generated in concrete manufacture.
Flash Joule heating for bulk graphene improves upon techniques like exfoliation from graphite and chemical vapor deposition on a metal foil that require much more effort and cost to produce just a little graphene. The process produces “turbostratic” graphene, with misaligned layers that are easy to separate.
The flash process happens in a custom-designed reactor that heats material quickly and emits all noncarbon elements as gas. Elements like oxygen and nitrogen that exit the flash reactor can all be trapped as small molecules because they have value. The flash process produces very little excess heat, channeling almost all of its energy into the target — the heat is concentrated in the carbon material and none in a surrounding reactor.
The researchers hope to produce a kilogram (2.2 pounds) a day of flash graphene within two years, starting with a project funded by the Department of Energy to convert US-sourced coal.