Synthesis and Properties

Synthesis in DNI falls into 3 major categories:

1. Synthesis of new MXenes through MAX synthesis. Typically, MXenes are synthesized through a topochemical selective etching process of MAX (Mn+1AXn) phase materials, where M is an early transition metal (Ti, V, Cr, Nb, etc.) A is Al, Ga, Si, S, etc., and X is carbon and/or nitrogen, and n is 1-3.1 By synthesizing MAX phase materials (Ti3AlC2, V2AlC, Nb4AlC3, Mo2Ti2AlC3, etc.) their corresponding MXenes (Ti3C2Tx, V2CTx, Nb4C3Tx, Mo2Ti2C3Tx, etc.) can be synthesized.2-4 Each aspect of MXene chemistry/structure including n (Ti2CTx vs. Ti3C2Tx), M (V2CTx vs. Ti2CTx), and X (Ti3C2Tx vs. Ti3CNTx) affects the resulting properties and applications.5 Within MXenes, there are X general classes synthesized to date: single M MXenes (Ti3C2Tx), ordered-double transition metal MXenes (Mo2Ti2C3Tx),2 solid-solution MXenes (Ti2-xVxCTx), and ordered divacancy MXenes (Mo1.33CTx).6 Thus far, over 30 MXenes have been discovered, with the potential for hundreds more.

2. New synthetic routes to etch MXenes. When MXenes were first discovered, the method of production was the use of high concentration HF.7 This HF would interact with the Al layer in MXenes, selectively removing them, while leaving the Mn+1Xn structure intact. This approach leads to the characteristic accordion-like structure of MXenes. In today’s language, we call this multilayer MXene. Afterwards, high-intensity sonication was carried out, leading to delamination MXene, with sizes in submicron range. After this initial discovery, different concentrations of HF were used, and this led to lower quantities of defects in the initial MXenes, and thus better properties. At this stage, a variety of intercalants (TMAOH, DMSO, etc.) were found to chemically delaminate the MXene flakes, rather than mechanically. A new method was discovered, termed the MILD method, that used a combination of HCl+LiF to produce HF in-situ and simultaneously delaminate the MXene by intercalating lithium ions into the structure.8 Since then, a new approach was developed using a combination of HF+HCl, followed by a separate delamination step with LiCl. These advances led to progressively larger and larger MXenes (now >10 μm). In addition to increasing optimize methods for removal of Al, there have been advances in selectively moving other A elements, such as Si or Ga.9-10

3. Nitridation of MXenes. The electronic properties of nitride-based MXenes were studied computationally, and it was found that they should possess higher stability and electrical conductivity, among other enhanced properties. However, synthesis of the MAX phase precursors is a challenge; there has been successful reports of only a few nitride MAX phases. Considering this, nitride materials are more thermodynamically favorable, thus, with appropriate conditions, it is possible to chemically convert carbide MXenes into nitride MXenes. Previously, we have utilized NH3 gas at high temperatures (600°C) to convert Mo2CTx and V2CTx into their nitridized forms, Mo2NTx and V2NTx, respectively.11 These nitride MXenes had three orders of magnitude higher electrical conductivity than their respective carbide forms. Using a similar approach, we have also converted salt-template grown oxides into 2D nitrides.12-13

Technical illustration
Technical illustration

Five Top Papers:

  1. Anasori, B.; Xie, Y.; Beidaghi, M.; Lu, J.; Hosler, B. C.; Hultman, L.; Kent, P. R. C.; Gogotsi, Y.; Barsoum, M. W., Two-Dimensional, Ordered, Double Transition Metals Carbides (MXenes). ACS Nano 2015, 9 (10) 9507-9516.
  2. Alhabeb, M.; Maleski, K.; Anasori, B.; Lelyukh, P.; Clark, L.; Sin, S.; Gogotsi, Y., Guidelines for Synthesis and Processing of 2D Titanium Carbide (Ti3C2Tx MXene). Chem. Mater. 2017, 29 (18), 7633-7644.
  3. Urbankowski, P.; Anasori, B.; Hantanasirisakul, K.; Yang, L.; Zhang, L.; Haines, B.; May, S.; Billinge, S. J. L.; Gogotsi, Y., 2D Molybdenum and Vanadium Nitrides Synthesized by Ammoniation of 2D Transition Metal Carbides (MXenes). Nanoscale 2017, 9, 17722-17730.
  4. Sokol, M.; Natu, V.; Kota, S.; Barsoum, M. W., On the Chemical Diversity of the MAX Phases. Trends Chem. 2019, 1 (2) 210-223.
  5. Xiao, X.; Wang, H.; Urbankowski, P.; Gogotsi, Y., Topochemical Synthesis of 2D Materials. Chem. Soc. Rev. 2018, 47 (23), 8744-8765.

References

  1. Sokol, M.; Natu, V.; Kota, S.; Barsoum, M. W., On the Chemical Diversity of the MAX Phases. Trends Chem. 2019, 1 (2) 210-223.
  2. Anasori, B.; Xie, Y.; Beidaghi, M.; Lu, J.; Hosler, B. C.; Hultman, L.; Kent, P. R. C.; Gogotsi, Y.; Barsoum, M. W., Two-Dimensional, Ordered, Double Transition Metals Carbides (MXenes). ACS Nano 2015, 9 (10) 9507-9516.
  3. Naguib, M.; Halim, J.; Lu, J.; Cook, K. M.; Hultman, L.; Gogotsi, Y.; Barsoum, M. W., New Two-dimensional Niobium and Vanadium Carbides as Promising Materials for Li-ion Batteries. J. Am. Chem. Soc. 2013, 135 (43), 15966-15969.
  4. Ghidiu, M.; Naguib, M.; Shi, C.; Mashtalir, O.; Pan, L. M.; Zhang, B.; Yang, J.; Gogotsi, Y.; Billing, S. J. L.; Barsoum, M. W., Synthesis and Characterization of Two-Dimensional Nb4C3 (MXene). Chem. Commun. 2012, 50, 9517-9520.
  5. Hantanasirisakul, K.; Alhabeb, M.; Lipatov, A.; Maleski, K.; Anasori, B.; Salles, P.; Ieosakulrat, C.; Pakawatpanurut, P.; Sinitskii, A.; May, S. J., Effects of Synthesis and Processing on Optoelectronic Properties of Titanium Carbonitride MXene. Chem. Mater. 2019, 31 (8), 2941-2951.
  6. Tao, Q.; Dahlqvist, M.; Lu, J.; Kota, S.; Meshkian, R.; Halim, J.; Palisaitis, J.; Hultman, L.; Barsoum, M. W.; Persson, P. O. A.; Rosen, J., Two-dimensional Mo1.33C MXene with Divacancy Ordering Prepared from Parent 3D Laminate with In-plane Chemical Ordering. Nat. Commun. 2017, 8, 14949.
  7. Naguib, M.; Mashtalir, O.; Carle, J.; Presser, V.; Lu, J.; Hultman, L.; Gogotsi, Y.; Barsoum, M. W., Two-dimensional Transition Metal Carbides. ACS Nano 2012, 6 (2), 1322-31.
  8. Alhabeb, M.; Maleski, K.; Anasori, B.; Lelyukh, P.; Clark, L.; Sin, S.; Gogotsi, Y., Guidelines for Synthesis and Processing of 2D Titanium Carbide (Ti3C2Tx MXene). Chem. Mater. 2017, 29 (18), 7633-7644.
  9. Alhabeb, M.; Maleski, K.; Mathis, T. S.; Sarycheva, A.; Hatter, C. B.; Uzun, S.; Levitt, A.; Gogotsi, Y., Selective Etching of Silicon from Ti3SiC2 (MAX) Produces 2D Titanium Carbide (MXene). Angew. Chem. Int. Ed. 2018, 130 (19), 5542-5546.
  10. Meshkian, R.; Näslund, L.-Å.; Halim, J.; Lu, J.; Barsoum, M. W.; Rosen, J., Synthesis of two-dimensional molybdenum carbide, Mo2C, from the gallium based atomic laminate Mo2Ga2C. Scripta Materialia 2015, 108, 147-150.
  11. Urbankowski, P.; Anasori, B.; Hantanasirisakul, K.; Yang, L.; Zhang, L.; Haines, B.; May, S.; Billinge, S. J. L.; Gogotsi, Y., 2D Molybdenum and Vanadium Nitrides Synthesized by Ammoniation of 2D Transition Metal Carbides (MXenes). Nanoscale 2017, 9, 17722-17730.
  12. Xiao, X.; Urbankowski, P.; Hantanasirisakul, K.; Yang, Y.; Sasaki, S.; Yang, L.; Chen, C.; Wang, H.; Miao, L.; Tolbert, S. H., Scalable Synthesis of Ultrathin Mn3N2 Exhibiting Room‐Temperature Antiferromagnetism. Adv. Funct. Mater. 2019, 29 (17), 1809001.
  13. Xiao, X.; Wang, H.; Urbankowski, P.; Gogotsi, Y., Topochemical Synthesis of 2D Materials. Chem. Soc. Rev. 2018, 47 (23), 8744-8765.