A new method to make ‘defective’ graphene could provide the key to the the single-atomic layer material finding its place in the materials world. A team of researchers has now developed a simple electrochemical approach which allows defects to intentionally be created in the graphene, altering its electrical and mechanical properties and making the material even more useful.
Electrochemical synthesis is the technique the researchers used to break graphite flakes into graphene layers. By altering the voltage they were able to change the resulting graphene’s thickness, flake area, and number of defects, all of which alter the properties of graphene.
Mario Hofmann, a researcher at National Cheng Kung University in Taiwan, explains:
“Graphene is basically a metal, so it’s somewhat boring! But when you start adding defects you begin to get interesting effects.”
More exacting control over the amount and nature of defects could bring about new applications of graphene in drug delivery or electronics.
“Whilst electrochemistry has been around for a long time it is a powerful tool for nanotechnology because it’s so finely tuneable.” continues Hofmann. “In graphene production we can really take advantage of this control to produce defects.”
Carefully manipulating the voltage has enabled the team to have a previously unknown level of control of the amount of these defects.
The team created a system of pulsed instead of continuous voltages. This allowed them to unravel the exfoliation mechanism.
In order to monitor the evolution of the graphene in the solvent they found that simply tracking the solution’s transparency could give them quantitative information on the efficiency and onset of exfoliation.
They next plan 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 defects.
Mario Hofmann et al
Controlling the properties of graphene produced by electrochemical exfoliation
Nanotechnology 26 335607 doi:10.1088/0957-4484/26/33/335607
Photo: Mario Hofmann is holding an example set up of the electrochemical synthesis. Credit: (c) Mario Hofmann / IOP Publishing