Researchers at Royal Melbourne Institute of Technology (RMIT) have found that graphene could better fulfill its potential when purified to remove silicon, doubling its electrical performance.

Despite researchers demonstrating countless possible applications of graphene, many people feel that graphene is thus far showing rather sluggish industrial adoption. Now, researchers based at RMIT have proposed a possible reason for this and suggested how graphene's 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% 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 reportedly 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.