Researchers from the Tulane University School of Science and Engineering have developed a new family of two-dimensional transition metal carbo-chalcogenides (TMCCs)—which can be considered a combination of two well-known families, TM carbides (MXenes) and TM dichalcogenides (TMDCs)—that researchers say has promising applications, including in advanced electronics and high-capacity batteries.
A paper on their work is published in the journal Advanced Materials.
Two-dimensional materials are nanomaterials with thickness in the nanometer size (nanometer is one millionth of a millimeter) and lateral dimensions thousands of times the thickness. Their flatness offers unique set of properties compared to bulk materials.
Naguib said TMDCs are a large family of materials that has been explored extensively and found to be very promising, especially for electrochemical energy storage and conversion. But, he said, one of the challenges in utilizing them is their low electrical conductivity and stability.
On the other hand, he said, transition metal carbides are excellent electrical conductors with much more powerful conductivity. Merging the two families into one is anticipated to have great potential for many applications such as batteries and supercapacitors, catalysis, sensors and electronics.
Instead of stacking the two different materials like Lego building blocks with many problematic interfaces, here we develop a new 2D material that has the combination of both compositions without any interface.
The team used an electrochemical-assisted exfoliation process by inserting lithium ions in-between the layers of bulk transition metals carbo-chalcogenides followed by agitation in water, said Ahmad Majed, the first author of the paper and a doctoral candidate in Materials Physics and Engineering at Tulane working in Naguib’s group.
Unlike other exotic nanomaterials, Majed said, the process of making these 2D TMCC nanomaterials is simple and scalable.
Single sheets are successfully obtained from multilayered Nb2S2C and Ta2S2C using electrochemical lithiation followed by sonication in water. The parent multilayered TMCCs are synthesized using a simple, scalable solid-state synthesis followed by a topochemical reaction. Superconductivity transition is observed at 7.55 K for Nb2S2C.
The delaminated Nb2S2C outperforms both multilayered Nb2S2C and delaminated NbS2 as an electrode material for Li-ion batteries. Ab initio calculations predict the elastic constant of TMCC to be over 50% higher than that of TMDC.
This study was supported by Naguib’s National Science Foundation Career Award that he received less than a year ago.
Majed, A., Kothakonda, M., Wang, F., Tseng, E.N., Prenger, K., Zhang, X., Persson, P.O., Wei, J., Sun, J. and Naguib, M. (2022), “Transition Metal Carbo-Chalcogenide “TMCC” a New Family of Two-dimensional Materials.” Adv. Mater. doi: 10.1002/adma.202200574