Researchers at KTH Royal Institute of Technology claim to have significantly advanced sustainable nanomaterial synthesis by creating a scalable and repeatable process for creating graphene oxide (GO) nanosheets from commercial carbon fibers, as published in the scientific journal Small.
“The future of auto manufacturing will build on battery-based power, and the question is where the graphite will be sourced? They are going to need alternatives," says researcher Richard Olsson, seen here in the lab holding two sources of graphene, a spool of carbon fiber and a piece of mined graphite. Image Credit: KTH Royal Institute of Technology
Exfoliating carbon fibers with nitric acid produces high yields of one-atom-thick graphene oxide sheets with properties similar to commercial GO derived from mined graphite.
When its thin sheets stack together to form layers resembling graphite, graphene oxide—an extensively researched nanomaterial—can be utilized in automobile batteries. It is also helpful in electronic devices, water purification, and high-performance composites. However, because graphite varies in purity, synthesis from mined graphite necessitates harsh chemicals and frequently produces inconsistent materials.
Biomass is a Possible Source
According to Richard Olsson, a Professor of Polymeric Materials at KTH, carbon fibers made from polyacrylonitrile (PAN), a common polymer that oxidizes and graphitizes at high temperatures, were used to prove the concept. According to him, the process could be repeated using different raw materials, like biomass or forest industry byproducts.
Olsson points to the electric vehicle battery market as one that can benefit from the new technology.
The core of graphite battery functionality can be found in the layered graphene inside, which can be harvested from commercial carbon fibers using this method. The future of auto manufacturing will build on battery-based power, and the question is where the graphite will be sourced? They are going to need alternatives.
Richard Olsson, Professor, Polymeric Materials, KTH Royal Institute of Technology
Graphene Sheets Peel Off
The method transforms carbon fibers through electrochemical oxidation in a water and nitric acid bath. Similar to how oxidation manifests as rust on an automobile, the bath functions as a conductor, and when an electric current passes through carbon fiber, the material starts to lose electrons, changing the surface. In this instance, the transformation results in the removal of layers of nanoscale graphene oxide from the surface of the carbon fibers.
The researchers found that a mere 5 % nitric acid was ideal for forming these minuscule nanosheets, which had a uniform thickness of roughly 0.9 nm and ranged in size from 0.1 to 1 µm. Interestingly, unlike GO synthesized from natural, mined graphite, which typically takes the form of polygons, the GO nanosheets created in this manner emerged in circular and elliptical shapes.
High Yield and Quality
The new method yields 200 mg of GO per gram of carbon fiber, which is higher than the current synthetic methods. Because of its effective conversion rate, it can be produced on a large scale, solving a significant problem in the synthesis of nanomaterials.
The researchers used various sophisticated techniques to analyze and measure the material's structure and properties to ensure the nanosheets fulfilled quality standards.
The study also investigated two effective methods for removing protective polymer coatings from commercial carbon fibers prior to oxidation: heating at 580 °C for two hours and shock-heating to 1200 °C for three seconds. The study showed that an important factor in the electrochemical exfoliation process is the electrical conduction within the fibers.
Investigating biobased sources for carbon fibers and learning more about the process are among the researchers' next steps, according to Olsson.
Journal Reference:
Español, A., et al. (2025) Making Synthetic 2D Graphene Oxide Nanosheets by Electrochemical Oxidation of Commercial Carbon Fibres. Small. doi.org/10.1002/smll.202408972