Performance of 'supermaterial' graphene in electronics can be almost doubled by removing silicon contamination from it, according to a new study by scientists from RMIT University in Australia.
Graphene is an allotrope of carbon, which consists of a one-atom thick lattice of carbon atoms. It is known for some uncommon properties. It is electrically conductive, super-capacitive, biodegradable, and a transparent material that can take almost any shape. Graphene is ultra-light but 200 times stronger than steel. It can conduct electricity 10 times better than copper.
Graphene is said to be a transformative material for flexible electronics. It can help create unbreakable phone screens, flexible computers, powerful chips, bio-sensors, new supercomputers and even space elevators.
But, despite its many properties, graphene has failed, until now, to live up to its potential.
Now, a group of scientists, led by Dr. Dorna Esrafilzadeh and Dr. Rouhollah Ali Jalili from RMIT University, state that they have finally found the reason behind the disappointing performance of graphene. In their study, these scientists describe a new approach that can help industry produce higher performing graphene.
Scientists collected commercially available graphene samples and examined them with a powerful scanning transition electron microscope. They found that these samples were contaminated with high levels of silicon. Silicon in graphene comes from the natural graphite, which is used as the raw material to make graphene. When graphite is processed, silicon impurities are left in the samples, which eventually hamper the performance of graphene.
"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 (2D) materials," said Esrafilzadeh.
When researchers used contaminated graphene as electrode in their tests, it was found to perform up to 50 per cent worse.
"This level of inconsistency may have stymied the emergence of major industry applications for graphene-based systems," Esrafilzadeh added.
Researchers further revealed that graphene becomes vulnerable to surface contamination because of its two-dimensional (2-D) structure.
When they used pure graphene (without any silicon contamination) samples to build a supercapacitor, it was found to perform exceptionally well, and demonstrated the biggest capacity to hold electric charge for any graphene sample so far.
A pure graphene sample was also used to create a humidity sensor, and it also exhibited the highest level of sensitivity.
"We hope this research will help to unlock the exciting potential of these materials."
The findings of the study are published in journal Nature Communications.
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