Graphene R&D held back by fake ‘black powders’

A wonder material that consists simply of sheets of carbon atoms – graphene - is making waves across the scientific community, but research is being hampered by low-quality, fake material.

Graphene is one of the thinnest and strongest materials known to man, and is being tested for a myriad of uses including super-strong plastics, ultra-fast transistors in electronics as well as improved energy storage and energy generation devices, biosensors and drug delivery systems.

The prevalence of counterfeit materials being passed off as high-grade is threatening to have a negative impact on the emerging industry, according to researchers from the National University of Singapore (NUS).

“It is alarming to uncover that producers are labelling black powders as graphene and selling them for top dollar, while in reality, they contain mostly cheap graphite,” says Professor Antonio Castro Neto, director of the NUS Centre for Advanced 2D Materials.

“There is a strong need to set up stringent standards for graphene characterisation and production to create a healthy and reliable graphene market worldwide,” he adds.

Graphene is typically produced by exfoliating graphite, which can be found in common pencil leads, into a powder, submerging this powder into a liquid, and then separating the tiniest graphene flakes by using sound energy to vibrate the mixture. The aim of this synthesis is to produce the thinnest graphene possible.

Pure graphene would be just one atomic layer thick, however the International Organization for Standardisation (ISO) states that stacks of graphene flakes up to ten layers thick can still behave like graphene.

With this in mind, Castro Neto and his team set out to develop a systematic and reliable method for establishing the quality of graphene samples from around the world, using a wide range of analytical techniques and samples from many suppliers.

Upon analysing samples from over 60 different providers from the Americas, Asia and Europe, the NUS team discovered that the majority contained less than 10 per cent of what can be considered graphene flakes. The bulk of the samples was graphite powder that was not exfoliated properly. The work is published in the journal Advanced Materials.

“Whether producers of the counterfeit graphene are aware of the poor quality is unclear. Regardless, the lack of standards for graphene production gives rise to bad quality of the material sold in the open market. This has been stalling the development of the future applications,” said Castro Neto.

“We hope that our results will speed up the process of standardisation of graphene within ISO as there is a huge market need for that.”