New Reactor System Could Enable Large-Scale Production of 2D Nanomaterials

For over ten years, two-dimensional (2D) nanomaterials, like graphene, have been hyped as crucial materials for making improved antennas, batteries, microchips, and a host of other devices.

However, one major challenge of utilizing these atom-thin building materials for future technology is how to produce these materials in large quantities without affecting their quality. That is no longer a problem for MXenes, which are one of the new and most promising kinds of 2D nanomaterials.

A research team at the Materials Research Center in Ukraine and Drexel University has developed a new system that can be used for making large amounts of the 2D material without losing its special properties.

The researchers recently reported in the Advanced Engineering Materials journal that a laboratory-scale reactor system now has the ability to transform a ceramic precursor material into a bulk powdery black MXene titanium carbide in amounts as large as 50 g per batch. This reactor system was developed at the Materials Research Center in Kyiv.

One crucial step for achieving manufacturing viability is to prove that large material batches can indeed be refined and generated with consistency.

In the case of MXene materials, which have already demonstrated their potential in prototype devices for health care, communication, energy, storing, and computing, achieving manufacturing standards is the home stretch for mainstream application.

Proving a material has certain properties is one thing, but proving that it can overcome the practical challenges of manufacturing is an entirely different hurdle—this study reports on an important step in this direction. This means that MXene can be considered for widespread use in electronics and energy storage devices.

Yury Gogotsi, PhD, Distinguished University and Bach Professor, College of Engineering, Drexel University

Gogotsi is also the study’s lead author and has pioneered the research and development of MXene materials.

At Drexel University, scientists have been synthesizing small quantities of MXene material—usually 1 g or less—since the material was first synthesized in 2011. This layered nanomaterial, which resembles a powder in its dry form, begins as a piece of ceramic known as a MAX phase.

A mixture of hydrochloric and hydrofluoric acid etches away some parts of the material upon interacting with the MAX phase and produces the nanometer-thin flakes that are a characteristic of MXene materials.

This process in the laboratory would be performed in a 60 mL container in which the ingredients are added and mixed manually. To handle the process more carefully and at a larger scale, the researchers use a screw feeder device and a one-liter reactor chamber to add the MAX phase accurately.

While one inlet introduces the reactants evenly into the reactor, another one eases the gas pressure at the time of the reaction. Uniform and thorough mixing are ensured by a uniquely developed mixing blade. A cooling jacket around the reactor allows the researchers to modify the reaction temperature. The whole process is computerized and managed by a software program developed by a research team at the Materials Research Center.

Reportedly, the team has effectively used the reactor to produce almost 50 g of MXene powder from 50 g of MAX phase precursor material in approximately two days. This also included the time needed for cleaning and drying the product.

Students at the Materials Science and Engineering Department of Drexel University performed a battery of tests that revealed that the MXene synthesized by the reactor retained the morphology as well as the physical and electrochemical properties of the original substance developed in the laboratory.

Such advancement places MXenes in a group that has only a few 2D materials: materials that can be effectively synthesized in industrial-size quantities. However, MXene-making is a subtractive manufacturing procedure in which pieces of raw material are etched, just like planing down lumber, and so it is different from other additive processes used for making a variety of other 2D nanomaterials.

Most 2D materials are made using a bottom-up approach. This is where the atoms are added individually, one by one. These materials can be grown on specific surfaces or by depositing atoms using very expensive equipment. But even with these expensive machines and catalysts used, the production batches are time-consuming, small and still prohibitively expensive for widespread use beyond small electronic devices.

Christopher Shuck, PhD, Post-Doctoral Researcher, A.J. Drexel Nanomaterials Institute

In addition, MXene materials gain from a group of physical properties that ease their path, right from the processed material to the end product, a barrier that has tripped up even sophisticated materials that are extensively used these days.

“It typically takes quite a while to build out the technology and processing to get nanomaterials in an industrially usable form,” added Gogotsi. “It’s not just a matter of producing them in large quantities, it often requires inventing completely new machinery and processes to get them in a form that can be inserted into the manufacturing process—of a microchip or cell phone component, for example.”

But according to Gogotsi, MXenes can be easily integrated into the manufacturing line.

One huge benefit to MXenes is that they be used as a powder right after synthesis or they can be dispersed in water forming stable colloidal solutions. Water is the least expensive and the safest solvent. And with the process that we’ve developed, we can stamp or print tens of thousands of small and thin devices, such as supercapacitors or RFID tags, from material made in one batch.

Yury Gogotsi, PhD, Distinguished University and Bach Professor, College of Engineering, Drexel University

This implies that MXenes can be used in any of the regular variety of additive manufacturing systems—such as spraying, dip coating, printing, and extrusion—after a single processing step.

Murata Manufacturing Co, Ltd., an electronics component company situated in Kyoto, Japan, and several other companies are looking to advance the applications of MXene materials. Murata Manufacturing is currently developing the MXene technology for use in many advanced applications.

“The most exciting part about this process is that there is fundamentally no limiting factor to an industrial scale-up,” Gogotsi added. “There are more and more companies producing MAX phases in large batches, and a number of those are made using abundant precursor materials. And MXenes are among very few 2D materials that can be produced by wet chemical synthesis at large scale using conventional reaction engineering equipment and designs.”

The study was financially supported by the U.S. Office of the Director of National Intelligence, the U.S. Department of Energy, the European Commission, and the National Science Foundation.

Apart from Gogotsi and Shuck, Asia Sarycheva, Mark Anayee, Ariana Levitt, Yuanzhe Zhu, and Simge Uzun from Drexel University; and Vitaliy Balitskiy, Veronika Zahorodna, and Oleksiy Gogotsi from the Materials Research Center took part in the study.

Source: https://drexel.edu/