He graphene It is one of the key materials in the development of technology due to its ability to conduct electricity and its versatility. However, manufacturing it is still very expensive, hence the interest that a technique has aroused. new to manufacture sheets of this material and other similar ones, which makes the process cheaper and allows production to be scaled.
The development has been carried out by researchers from the Institute of Materials Science of Madrid (ICMM-CSIC) have developed a novel technique of mechanical exfoliation to obtain more and better nanosheets of van der Waals materials (those that have a layered structure, such as graphene) much cheaper. The results of the work have just been published in the journal Small Methods.
How graphene sheets are currently manufactured and what the new technique is like
Until now, heThe mechanical exfoliation carried out to obtain sheets of graphene and other similar materials consists of using an adhesive tape on the material to be exfoliated.. When the tape is separated from the material, tiny layers are stuck to it, which are those that have the specific properties sought in each material. However, while this method is inexpensive and provides high-quality flakes, it is not as scalable as others. To solve this, A roller system has been designed with cylinders made of a polymer (polyoxymethylene) that rotate facing each other..
The rollers are covered with adhesive tape and the material to be exfoliated is placed on them.. When both cylinders are rotated, they touch each other as they rotate, replicating on a larger scale the adhesion/detachment process that is done in manual mechanical peeling. “At the end of the process, the adhesive tape is completely covered with graphene, molybdenum disulfide or any other layered material,” he explains. Carmen Munueraresearcher at ICMM-CSIC and one of the authors of the work.
To prevent the rollers from always touching at the same point, it has been decided to manufacture them with diameters that correspond to large prime numbers, which ensures “that many revolutions are required before the cylinders return to their initial relative alignment”, points out Andrés Castellanos-Gómez, also a scientist at ICMM-CSIC and lead author of the study. Thanks to this, it is achieved that the material is distributed evenly on the adhesive tape.
What advantages does the new device have for manufacturing graphene sheets?
Scientists have designed a device that is not only versatile because can be used with different two-dimensional materials, but the result is optimal (the sheets have a high aspect ratio by achieving a good lateral size) and the transfer of the material is simple. “With our method, we have achieved a remarkable balance between cost, scalability and performance“, highlights Munuera, who points out that, since the technique does not have solvents, it does not leave residues between the sheets, “which would have a negative impact on factors such as conductivity.”
The equipment is quite small in size, which allows working with it in small spaces, necessary for working with materials that degrade in environmental conditions.. On the other hand, the researchers have shared the plans of their invention in the paper itself so that any other laboratory can reproduce it and work with it.
“This method offers opportunities for automation, which could boost its commercial use,” adds Munuera. “It is an attractive option for applications in electronics and optoelectronics, and for the manufacture of sensors and cost-effective electronic components for flexible devices,” concludes Castellanos-Gómez.