Graphene concept art

Graphene’s lacklustre adoption rate blamed on silicon contamination

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According to researchers at Royal Melbourne Institute of Technology (RMIT), graphene could begin to fulfil its great potential when purified to remove silicon, doubling its electrical performance.

Graphene – an atom-thick hexagonal lattice of carbon atoms – is the strongest material ever tested, as well as having impressive electrical and thermal properties, also being flexible and transparent. Given these properties, engineers have described graphene as a “supermaterial” or “wonder material” and foretold a “graphene revolution” to transform electronics and other fields. For instance, the 2D material could serve as an ideal material in electricity storage and new sensors which perform best with high surface areas.

In 2010, Andre Geim and Konstantin Novoselov won the Nobel Prize for Physics for their ground-breaking work demonstrating the properties of graphene.

However, despite researchers demonstrating countless possible applications of graphene, it has failed to live up to the hype, with sluggish industrial adoption.

Now, researchers based at RMIT writing in Nature Communications have proposed a possible reason for the failure of graphene to transform electronics and suggested how its full potential could be unlocked.

The scientists studied commercially-available samples of graphene atom by atom using a scanning transition electron microscope. They found that the graphene was contaminated by silicon, which is present in natural graphite, and had not been fully removed when processed for use. Graphene’s extremely high surface area – while being graphene’s unique selling point – also makes it vulnerable to surface contamination.

“We found high levels of silicon contamination in commercially available graphene, with massive impacts on the material’s performance,” said Dr Dorna Esrafilzadeh, who led the study. “We believe this contamination is at the heart of many seemingly inconsistent reports on the properties of graphene and perhaps many other atomically thin [2D] materials. Now we know why it has not been performing as promised and what needs to be done to harness its full potential.”

The testing also demonstrated the influence that these silicon impurities have on the graphene’s performance: the contaminated graphene performed up to 50 per cent worse when tested as electrodes compared with pure graphene, which performed extraordinarily well when used to build a supercapacitator.

“This level of inconsistency may have stymied the emergence of major industry applications for graphene-based systems,” said Esrafilzadeh. “But it’s also preventing the development of regulatory frameworks governing the implementation of such layered nanomaterials, which are destined to become the backbone of next-generation devices.”

The researchers used their purified graphene to build a versatile humidity sensor, which worked with the highest sensitivity and the lowest limit of detection ever reported.

“We hope this research will help to unlock the exciting potential of these materials,” said Esrafilzadeh.

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