Are discarded peanut shells the affordable and sustainable path to graphene?

UNSW Sydney researchers have produced small quantities of high-quality graphene via a new process that uses waste peanut shells. The development could open the door to cheaper, more sustainable electronics and energy storage devices, and could help transform agricultural waste into valuable products inside phones and computers that are used every day by billions of people around the world, UNSW Sydney said.

“Graphene is famous for being one of the thinnest, strongest and most conductive materials known to science,” said Professor Guan Yeoh from the School of Mechanical and Manufacturing Engineering, who led the team. “It is made up of a single layer of carbon atoms arranged in a hexagonal lattice, but is hundreds of times stronger than steel, conducts electricity and heat better than copper and is almost completely transparent.”

Those characteristics make graphene extremely useful in a range of technologies. These range from batteries and solar panels to touch screens, flexible electronics and super-fast transistors. Yet the material is expensive and difficult to produce in large quantities — requiring chemicals and energy-intensive methods. Hence the potential benefits in finding affordable and sustainable alternatives.

“There are about 55 million tonnes of peanut crops produced globally every year, yet most of the waste from the shell is either discarded or recycled into low-value applications that don’t maximise their full potential,” Yeoh said. “What we have shown in this work is that basic peanut shells can be turned into high-quality graphene, using much lower energy than is currently required and therefore at a lower cost. We also do not need to use any chemicals, so there is an added environmental benefit.

“Graphene is useful for making stronger, lighter and more conductive materials for applications in electronics, energy storage, medical devices and even flexible technologies like sensors, solar cells and wearable tech,” Yeoh added. “The demand for many of those things is increasing rapidly, so it’s exciting to find a way of producing more graphene in a cost-effective way — and by using material that would otherwise be waste.”

The first breakthrough was to recognise that peanut shells are packed with lignin, a naturally occurring polymer in plants which contains a lot of carbon. This gave the researchers the idea to grind up the shells and use a series of heat treatments to unlock their potential for graphene production. The researchers have published open access about the study in the Chemical Engineering Journal Advances, and you can read it at doi.org/10.1016/j.ceja.2026.101099.

Image: The UNSW team have produced small quantities of high-quality graphene via a new process that uses waste peanut shells. Credit: Guan Yeoh/UNSW