For the first time, scientists of Tomsk Polytechnic University succeeded to modify graphene through the combination of two methods based on the functionalization with diazonium salts and laser processing. They obtained a high-quality material with properties necessary for flexible electronics. The paper Beyond graphene oxide: laser engineering functionalized graphene for flexible electronics was published in Materials Horizons (Q1, IF 14.356) and selected for the issue cover.
Photo: Artistic illustration of laser removal of diazonium salts (marked in red) from graphene
Graphene is the strongest and lightest conductive carbon compound. It can be used for the production of solar panels, smartphone screens, flexible and thin electronics, and even in water filters, since a graphene film passes water molecules and at the same time delays all other compounds.
The methods applied to synthesize and integrate graphene into complex structures involve oxidation of the material with its subsequent reduction. However, oxidation is a very destructive method that damages the structure of graphene. Furthermore, oxidized graphene is non-conductive and does not have a number of other important properties. The methods are also time demanding and energy consuming.
“We used graphene, functionalized with diazonium salts, which was then processed with high-intensity laser radiation. The resulting material has much better conductivity, resistance to degradation and water corrosion, and excellent flexibility. Nobody has ever used the combination of these two methods to modify graphene,”
Raul Rodriguez, one of the authors of the research paper, professor of the TPU Research School of Chemistry & Applied Biomedical Sciences, says.
Graphite is placed in an electrolytic cell with a solution of diazonium salts. Under electrochemical reactions, flakes of the material began to exfoliate. Resulting stable suspension can be applied to almost any surface.
“The suspension was applied to polymer substrates and then processed with a laser. Another advantage is high accuracy of the processing. We can “draw” a structure on the surface with a laser, for example, electrical circuits,”
Evgenia Sheremet, a member of the research team, professor of Research School of High-Energy Physics, says.
A number of sensors were made based on the obtained materials. They include a human respiration sensor integrable into a mask, and a sensor capturing ethanol in the air. In the future, modified graphene is planned to design various specialized devices and develop new materials.
The project team includes the scientists from the TPU Research School of Chemistry & Applied Biomedical Sciences, the TPU Research School of High-Energy Physics, the TPU School of Earth Sciences & Engineering, and scientists from Germany, Holland, France, and China.
“The idea for this project appeared at the TPU Research School of Chemistry & Applied Biomedical Sciences due to a comfortable environment for planning and implementing interdisciplinary research projects and support of TPU in providing research equipment,” the scientists say.