A new method for tweaking the properties of graphene by creating defects in the ultra-thin material has been unveiled by scientists.
The researchers used a technique called electrochemical exfoliation to strip graphene layers from graphite flakes. By varying the voltage they discovered they could change the resulting graphene’s thickness, flake area, and number of defects – all of which alter its electrical and mechanical properties.
The one-atom-thick material has gained a lot of attention in recent years, but research has shown that the material's defective counterpart graphene oxide could be first to carve out a significant market share as polymer fillers and battery electrodes.
More precise control over the amount and nature of defects could bring about new applications of graphene in everything from drug delivery or electronics, according to the researchers from National Cheng Kung University in Taiwan.
“Graphene is basically a metal – so it’s somewhat boring! But when you start adding defects you begin to get interesting effects," says Mario Hofmann, lead author of a paper published in the journal Nanotechnology. “Whilst electrochemistry has been around for a long time, it is a powerful tool for nanotechnology because it’s so finely tuneable.”
The team used electrical and optical measurements to unravel the exfoliation mechanism that removed graphene layers from the graphite and discovered that by using pulsed instead of continuous voltages they were able to control the properties of the resulting graphene.
Hofmann said: “In graphene production we can really take advantage of this control to produce defects.” Carefully controlling the voltage has allowed the team a previously unknown level of control of the amount of these defects.
The team now plans to study the effects of adjusting the pulse durations throughout the exfoliation process to improve the amount of exfoliated graphene and introduce more complex pulse shapes to selectively produce certain types of graphene defect.