Researchers have registered the biggest electrical charge capacity for graphene by removing silicon contamination, unlocking the potential of the supermaterial.
A team at RMIT in Melbourne demonstrated the effectiveness of using pure graphene over contaminated graphene to build a supercapacitator, doubling the material’s performance and coming closer to its predicted theoretical capacity.
Dr Dorna Esrafilzadeh at RMIT: “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.
“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.”
The team, led by Dr Esrafilzadeh and Dr Rouhollah Ali Jalili, inspected commercially available graphene samples, atom by atom, with a scanning transition electron microscope.
Tests showed high levels of contamination, with the silicon present in natural graphite not being fully removed when processed. Contaminated material performed up to 50 percent worse when tested as electrodes.
The two-dimensional property of graphene sheeting, which is only one atom thick, makes it ideal for electricity storage and new sensor tech that relies on high surface areas.
Graphene conducts heat and electricity 10 times better than copper and was hailed as a transformative material for flexible electronics, computer chips, solar panels, water filters and bio-sensors. Performance has been mixed and industry adoption slow, and the university’s study has identified silicon contamination as the cause.
With RMIT’s Centre for Advanced Materials and Industrial Chemistry, the team also used pure graphene to build a versatile humidity sensor with the highest sensitivity and lowest limit of detection ever reported.