Technological watch

Rice University scientists employed a process to make . The lab of Rice chemist James Tour modified a method to make flash graphene to enhance it for recycling plastic into graphene. The lab’s study appears in the American Chemical Society journal ACS Nano.
Producing High-quality Turbostratic Graphene
Instead of raising the temperature of a carbon source with direct current, as in the original process, the lab first exposes plastic waste to around eight seconds of high-intensity alternating current, followed by the DC jolt.
The products are high-quality turbostratic graphene, a valuable and soluble substance that can be used to enhance electronics, composites, concrete and other materials, and carbon oligomers, molecules that can be vented away from the graphene for use in other applications.
“We also produce considerable amount of hydrogen, which is a clean fuel, in our flashing process,” said Rice graduate student and lead author Wala Algozeeb.
Tour estimated that at industrial scale, the ACDC process could produce graphene for about $125 in electricity costs per ton of plastic waste.
“We showed in the original paper that plastic could be converted, but the quality of the graphene wasn’t as good as we wanted it to be. Now, by using a different sequence of electrical pulses, we can see a big difference,” Tour said.
Flash Joule Conversion Eliminates Expense Associated with Recycling Plastic
Flash joule conversion eliminates much of the expense associated with , including sorting and cleaning that require energy and water. Rather than recycling plastic into pellets that sell for $2,000 a ton, it could be upcycled to graphene, which has a much higher value. There’s an economic as well as an environmental incentive.
Researchers are working to refine the flash graphene process for other materials, especially for food waste. They are working toward generating a good pulse sequence to convert food waste into very high-quality graphene with as little emission as possible.
The new study follows another recent paper that characterizes flash graphene produced from carbon black via direct current joule heating. That paper, also in ACS Nano, combined microscopy and simulations to show two distinct morphologies: turbostratic graphene and wrinkled graphene sheets. The study described how and why the rearranged carbon atoms would take one form or the other, and that the ratio can be controlled by adjusting the duration of the flash.