National University of Singapore (NUS) scientists have developed an economical and industrially viable strategy to produce graphene. The new technique addresses the long-standing challenge of an efficient process for large-scale production of graphene, and offers production potential for sustainable synthesis of the material.

Image of the printed graphene aerogel (200 mg, 50 mg cm−3) supporting 2500 times of its weight. Image Credit: Nature Communications. Click image for the largest view.

The research was conducted in collaboration with Fudan University and the findings were published in prestigious scientific journal Nature Communications.

Graphene is a two-dimensional material with a honeycomb structure of only one atom’s thickness. Expected to be a 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 to produce high-quality graphene affordably on a large scale, however, continues to pose a hindrance to its widespread adoption by industries.

The conventional method of producing graphene utilizes sound energy or shearing forces to exfoliate graphene layers from graphite, and then dispersing the layers in very large amounts of organic solvent. Using insufficient solvent causes the graphene layers to reattach themselves back into graphite. Today a yield of one kilogram of graphene requires at least one metric ton of organic solvent, making the method costly and quite environmentally unfriendly.

The NUS-led developmental research team, on the other hand, uses up to 50 times less solvent. This is achieved 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 having to increase the volume of solvent. The method also introduces electrostatic repulsive forces between the graphene layers and prevents them from reattaching themselves.

The resulting graphene slurry 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 spill in the sea.

Professor Loh Kian Ping from the Department of Chemistry at NUS Faculty of Science who is also the Head of 2D Materials Research at the NUS Center for Advanced 2D Materials led the research.

He said, “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.”

Its quite likely this technology is going to change the outlook for graphene marketing. So far graphene has been a laboratory item with lots of news and ideas. Perhaps now that the quantity can increase dramatically, graphene may get into some products. But ultimately there is going to need to be a race to the lowest cost provider and we finally have that first step. This is progress.


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