Study: MXene versatile material successfully mass-produced

The material was conceived in 2011 – “MXene is a two-dimensional nanomaterial with alternating metal and carbon layers, which has high electrical conductivity and can be combined with various metal compounds,” scientists explain in the statement, “ making it a material that can be utilized in various industries such as semiconductors, electronic devices, and sensors.” 

In order to efficiently utilize the material, researchers determined the type and quantity of molecules present on its surface. They uncovered that if the fluorine molecules are found on the surface, it leads to reduced electrical conductivity and less effective electromagnetic wave shielding. 

However, the incredibly thin texture of MXene – 1 nanometer thick makes it a challenging material to deal with despite the advancement of electron microscopes. It still takes several days to analyze the surface molecules. This limitation has hindered large-scale production until now.

The new technique enabled the easy measurement of MXene's molecular distribution, facilitating quality control during production. This breakthrough is anticipated to pave the way for mass production, which was previously unattainable.

The approach involved a two-dimensional material property prediction program. It was built on the concept that electrical conductivity or magnetic properties alter depending on the molecules affixed to the surface. 

MXene's magnetic transport properties

Scientists emphasized that their calculations pivot towards the magnetic transport properties of MXene. They succeeded in analyzing the type and amount of molecules adsorbed on the surface of MXene at atmospheric pressure and room temperature without any additional devices, the statement reported.

Upon looking closely, it was found that the MXene surface comprised the Hall Scattering Factor, which affects magnetic transport and changes dramatically depending on the type of surface molecules.

The change in electric charges relayed different values for the different surface molecules. Scientists observed that it was really high at 2.49 when fluorine was on the surface, It was 0.5 when oxygen was there and it was one when hydroxide was on the surface.

The values helped them understand the type of molecules present on the surface. The statement by the scientists explained that the Hall scattering coefficient has different applications based on the value of one. 

“If the value is lower than one, it can be applied to high-performance transistors, high-frequency generators, high-efficiency sensors, and photodetectors, and if the value is higher than one, it can be applied to thermoelectric materials and magnetic sensors.”

Given that the MXene's size is just a few nanometers or even smaller, it becomes possible to significantly shrink the size of the device it's used in and dramatically reduce the amount of power needed.

Seung-Cheol Lee, director of IKIST, stated: "Unlike previous studies that focused on the production and properties of pure MXene, this study is significant in that it provides a new method for surface molecular analysis to easily classify manufactured MXene.”

"By combining this result with experimental studies, we expect to be able to control the production process of MXene, which will be used to mass produce MXene with uniform quality."

The study was published on September 14 in the journal Nanoscale.

Study abstract:

Hall scattering factors of Sc2CF2, Sc2CO2 and Sc2C(OH)2 are calculated using Rode's iterative approach by solving the Boltzmann transport equation. This is carried out in conjunction with calculations based on density functional theory. The electrical transport in Sc2CF2, Sc2CO2 and Sc2C(OH)2 is modelled by accounting for both elastic (acoustic and piezoelectric) and inelastic (polar optical phonon) scattering. Polar optical phonon (POP) scattering is the most significant mechanism in these MXenes. We observe that there is a window of carrier concentration where the Hall factor acts dramatically; Sc2CF2 obtains an incredibly high value of 2.49 while Sc2CO2 achieves a very small value of approximately 0.5, and Sc2C(OH)2achieves the so called ideal value of 1. We propose in this paper that such Hall factor behaviour has significant promise in the field of surface group identification in MXenes, an issue that has long baffled researchers.