A team of researchers from the University of Zaragoza at the Institute of Nanoscience and Materials of Aragon (INMA), a joint center of CSIC and UNIZAR, and the Madrid Institute for Advanced Studies in Nanoscience (IMDEA Nanoscience) have developed a methodology with the potential to become an international benchmark for the production of 2D nanomaterials. Specifically, they have managed to generate MoS2 nanosheets, a semiconductor material with a wide application in the fields of nanoelectronics, photonics and electrocatalysis.
The prestigious journal ACS Nano (ACS publications) now publishes this work, led by University of Zaragoza INMA professors Víctor Sebastián and Jesús Santamaría, and IMDEA Nanoscience senior researcher Emilio Pérez. By means of ultra-fast exfoliation with the assisted use of microwaves, they have been able to obtain nanolayers with an average thickness of 4 atomic layers, with a lateral size of several microns and in a time as short as 90 seconds and with a yield approaching 50% (i.e., almost half of the processed material has the desired quality).
A method that overcomes previously unresolved shortcomings
The key to this proposed method, which could revolutionize the production of 2D nanomaterials on an industrial scale, is that for the first time it manages to meet the three requirements that any technology needs for its production, which consist of producing lamellar nanomaterials of very few atomic layers thick, with a lateral size large enough to allow their use in the aforementioned applications, and also with a yield high enough to be taken to industrial scale.
The importance of this field has prompted researchers from all over the world to propose, during the last few years, physical and chemical methods to achieve some of these objectives. This is where this collaboration of researchers from the University of Zaragoza at the Institute of Nanoscience and Materials of Aragon (CSIC-UNIZAR) and IMDEA Nanoscience (Madrid) is framed, and they have developed, as a result of the work of 3 years, a procedure capable of meeting all the above premises, opening the possibility of exploiting the process at industrial level.
“To better understand the process, if we imagine a book where each page is made up of a layer of atoms and where the electronic properties of the book as a whole differ from those of the individual pages, the challenge lies in removing groups of pages from the book (the fewer pages per group, the better) and maintaining the integrity of the page as far as possible,” explain researchers Víctor Sebastián and Jesús Santamaría. “Most of the methods used so far (such as ultrasound, for example) deteriorate the sheets and do not produce a homogeneous exfoliation. In contrast, in this work we have succeeded in infiltrating a low-boiling solvent between the films (“pages”). By subjecting the material to ultra-fast heating in a microwave field (MoS2 is a good microwave absorber), the interlayer solvent suddenly evaporates, generating an inter-lamellar pressure capable of separating the pages of the book. The excellent exfoliation obtained is being used to functionalize the nanomaterial and endow it with new properties.”
A multidisciplinary team
The article “Microwave-Driven Exfoliation of Bulk 2H-MoS2 after Acetonitrile Prewetting Produces Large-Area Ultrathin Flakes with Exceptionally High Yield” has been carried out by a multidisciplinary team of researchers linked to institutions in Aragon and Madrid.
In addition to the direction of the work by Víctor Sebastián and Jesús Santamaría, professors of the Department of Chemical Engineering and Environmental Technologies of the University of Zaragoza, researchers from the Institute of Nanoscience and Materials of Aragon (INMA), a joint center between the CSIC and the University of Zaragoza, the Institute of Health Research Aragon (IIS Aragon) and the Biomedical Research Center Network of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), have participated: Ramiro Quirós Ovies, predoctoral researcher at INMA and IMDEA Nanoscience, whose doctoral thesis is part of this work; María Laborda, graduate in Chemical Engineering at the University of Zaragoza; Natalia Martín Sabanés, Lucía Martín-Pérez, Sara Moreno-Da Silva, Enrique Burzurí and Emilio M. Pérez, from IMDEA Nanoscience.
Microwave-Driven Exfoliation of Bulk 2H-MoS2 after Acetonitrile Prewetting Produces Large-Area Ultrathin Flakes with Exceptionally High Yield
Ramiro Quirós-Ovies, María Laborda, Natalia Martín Sabanés, Lucía Martín-Pérez, Sara Moreno-Da Silva, Enrique Burzurí, Víctor Sebastian*, Emilio M. Pérez*, and Jesús Santamaría
ACS Nano Article ASAP