Producing Graphene With 50 Times Less Solvent

A Singapore-based research team has developed a cost-effective technique for the mass production of high-quality graphene.

AsianScientist (Apr. 17, 2018) – A research team led by the National University of Singapore (NUS) has developed an economical and industrially viable strategy to produce graphene. Their technique, described in Nature Communications, paves the way for sustainable synthesis of the material.

Graphene is a two-dimensional material with a honeycomb structure of only one-atom thickness. Dubbed as the material of the future, graphene exhibits unique electronic properties that can potentially be employed for a wide range of applications such as touch screens, conductive inks and fast-charging batteries. The difficulty of producing high-quality graphene affordably on a large scale, however, continues to hinder its widespread adoption.

The conventional method of producing graphene uses sound energy or shearing forces to exfoliate graphene layers from graphite. This is followed by dispersing the layers in large amounts of organic solvent. As insufficient solvent causes the graphene layers to reattach themselves back into graphite, yielding one kilogram of graphene currently requires at least one ton of organic solvent, making the method costly and environmentally unfriendly.

In this study, a research group led by Professor Loh Kian Ping at NUS has developed a method that requires 50 times less solvent to produce graphene. They achieved this by exfoliating pre-treated graphite under a highly alkaline condition to trigger flocculation, a process in which the graphene layers continuously cluster together to form graphene slurry without the need for an increased volume of solvent. The method also introduces electrostatic repulsive forces between the graphene layers and prevents them from reattaching themselves.

The resulting graphene slurry can be easily separated into monolayers when required or stored away for months. The slurry can also be used directly to 3D-print conductive graphene aerogels, an ultra-lightweight sponge-like material that can be used to remove oil spills in the sea.

“We have successfully demonstrated a unique exfoliation strategy for preparing high quality graphene and its composites. 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,” said Loh.


The article can be found at Dong et al. (2018) A Non-dispersion Strategy for Large-scale Production of Ultra-high Concentration Graphene Slurries in Water.

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Source: National University of Singapore; Photo: Shutterstock.
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