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Removing Silicon Contamination Doubles Graphene Performance

Graphene is the strongest material ever tested. It’s also flexible, transparent, and conducts heat and electricity ten times better than copper. When graphene research won the Nobel Prize for Physics in 2010 it was hailed as a transformative material for flexible electronics, more powerful computer chips and solar panels, water filters and biosensors, but its performance has been mixed and industry adoption slow.

Now a study published in Nature Communication ( has identified silicon contamination as the root cause of the disappointing results, and detailed how to produce high-performing pure graphene.

RMIT University researchers inspected commercially-available graphene samples, atom by atom, with a scanning transition electron microscope and found that silicon present in natural graphite, the raw material used to make graphene, was not being fully removed when processed. “We believe this contamination is at the heart of many seemingly inconsistent reports on the properties of graphene, and perhaps many other atomically thin two-dimensional materials,” Dr Dorna Esrafilzadeh said.

The testing also found that contaminated material performed up to 50% worse when tested as electrodes. “This level of inconsistency may have stymied the emergence of major industry applications for graphene-based systems. 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,” she said.

The two-dimensional property of graphene sheeting, which is only one atom thick, makes it ideal for electricity storage and new sensor technologies that rely on high surface area. However, this also makes graphene extremely vulnerable to surface contamination.

The researchers found that pure graphene used to build a supercapacitator had an extraordinary capacity to hold electrical charge – the biggest so far recorded for graphene, and within sight of the material’s theoretical capacity. The team then used pure graphene to build a versatile humidity sensor with the highest sensitivity and the lowest limit of detection ever reported.