Cleaning up graphene production
With graphene promising to revolutionize so many industries, we'll probably be churning out a lot of the stuff in the coming years. So, with current mass production techniques requiring the use of large amounts of organic solvents that aren't exactly great for the environment, the announcement of a new, more environmentally friendly and cost effective technique for the large-scale production of the wonder material comes as good news.
Currently, graphene production involves exfoliating one-atom-thin layers of graphene from graphite using sound energy or shear forces. These layers are then dispersed in large amounts of organic solvent to prevent them from reattaching and reforming back into graphite. This process requires at least one tonne of organic solvent to produce around just 1 kg (2.2 lb) of graphene.
Now researchers at the National University of Singapore (NUS) and Fudan University claim to have developed a new approach that cuts the amount of solvent required by up to half, making it much more economically viable and more environmentally friendly.
The new technique involves exfoliating partially oxidized graphite in a highly alkaline solution using high-rate shearing, which results in the graphene layers clustering together to form a graphene slurry while using significantly less solvent. Additionally, the graphene layers are prevented from reattaching themselves to reform graphite by the introduction of electrostatic repulsive forces between them.
The researchers say this graphene slurry can then be easily separated into single layers or used as a stock solution of graphene that can be stored for months until required. It can also be used to 3D print conductive polymer materials or graphene aerogels, which hold great potential for cleaning up oil spills in the ocean.
"We have successfully demonstrated a unique exfoliation strategy for preparing high quality graphene and its composites," says Professor Loh Kian Ping from NUS who led the research. "Our technique, which produces a high yield of crystalline graphene in the form of a concentrated slurry with a significantly smaller volume of solvent, is an attractive solution for industries to carry out large scale synthesis of this promising material in a cost-effective and sustainable manner."
The technique was detailed in a paper published in Nature Communications.