Physical forms of MXene materials exhibiting novel electrical and optical characteristics

Patent metadata

Field	Value
Publication number	US-11296243-B2
Application number	US-201916710454-A
Country	US
Kind code	B2
Filing date	Dec 11, 2019
Priority date	Sep 25, 2014
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

The present invention(s) is directed to novel conductive M n+1 X n (T s ) compositions exhibiting high volumetric capacitances, and methods of making the same. The present invention(s) is also directed to novel conductive M n+1 X n (T s ) compositions, methods of preparing transparent conductors using these materials, and products derived from these methods.

First claim

What is claimed:

1. A method comprising,
(a) applying a MXene dispersion onto a substrate surface, said MXene dispersion comprising at least one type of MXene platelets dispersed in a solvent; and
(b) removing at least a portion of solvent so as to provide a coated film of at least one layer of MXene platelets oriented to be essentially coplanar with the substrate surface,
said MXene platelets comprising a M n+1 X n (T s ) composition having at least one layer, each layer having a first and second surface, each layer comprising
a substantially two-dimensional array of crystal cells,
each crystal cell having an empirical formula of M n+1 X n , such that each X is positioned within an octahedral array of M,
wherein M is at least one Group 3, 4, 5, 6, or 7,
wherein each X is C, N, or a combination thereof and
n=1, 2, or 3;
wherein at least one of said surfaces of the layers has surface terminations, T s , independently comprising alkoxide, alkyl, carboxylate, halide, hydroxide, hydride, oxide, sub- oxide, nitride, sub-nitride, sulfide, sulfonate, thiol, or a combination thereof;
said coated film being electrically conductive and exhibiting:
(i) a resistivity in a range of from about 0.01 to about 1000 micro-ohm-meters,
(ii) an ability to transmit at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, or at least about 95% of incident light of at least one wavelength in a range of from about 300 nm to about 2000 nm
(iii) a ratio of DC conductivity, measured in Siemens/meter, to light absorbance, (including visible light absorbance), measured as a decadic absorbance per meter, of at least 0 . 1 Siemens measured at at least one wavelength in the range of 300 to 2500 nm;
(iv) a value of the real dielectric permittivity less than negative one for wavelengths greater than a threshold wavelength, for example, 500 nm; or
(v) a combination of any two or more of (i), (ii), (iii), and (iv),
wherein the M n−1 X n (T s ) composition comprises a plurality of M n+1 X n (T s ) platelets having at least one mean lateral dimension in a range of from about 0.1 micron to about 50 microns.

2. The method of claim 1 wherein the MXene dispersion is applied dropwise onto an optionally rotating substrate surface, during or after which the optionally substrate surface is made to rotate at a rate in a range of from about 300 rpm (rotations per minute) to about 5000 rpm.

3. The method of claim 1 , wherein the MXene dispersion is an aqueous dispersion optionally comprising one or more surfactants.

4. The method of claim 1 , wherein the MXene dispersion comprising an organic solvent.

5. The method of claim 1 , wherein the substrate is rigid.

6. The method of claim 1 , wherein the substrate is flexible.

7. The method of claim 1 , wherein the film has surface electrical resistivity in a range of from about 1 micro-ohm-meters to about 10 micro-ohm-meters, from about 10 micro-ohm-meters to about 100 micro-ohm-meters, from about 100 micro-ohm-meters to about 1000 micro-ohm-meters, from about 1000 micro-ohm-meters to about 10,000 micro-ohm-meters, or any combination of two or more of these ranges.

8. The method of claim 1 , wherein M is at least one Group 4, 5, 6, or 7 metal.

9. The method of claim 1 , wherein M is at least one of Hf, Cr, Mn, Mo, Nb, Sc, Ta, Ti, V, W, or Zr.

10. The method of claim 1 , wherein M is Ti, and n is 1 or 2.

11. The method of claim 1 , wherein M n+1 X n comprises Sc 2 C, S c2 N, Ti 2 C, Ti 2 N, V 2 C, V 2 N, Cr 2 C, Cr 2 N, Zr 2 C, Zr 2 N, Nb 2 C, Nb 2 N, Hf 2 C, Hf 2 N, Ta 2 C, Mo 2 C, Ti 3 C 2 , Ti 3 N 2 , V 3 C 2 , Ta 3 C 2 , Ta 3 N 2 , Mo 3 C 2 , (Cr 2/3 Ti 1/2 ) 3 C 2 , Ti 4 C 3 , Ti 4 N 3 , V 4 C 3 , V 4 N 3 , Ta 4 C 3 , Ta 4 N 3 , Nb 4 C 3 , or a combination thereof.

12. The method of claim 1 , the crystal cells having an empirical formula Ti 3 C 2 or Ti 2 C and wherein at least one of said surfaces of each layer is coated with surface terminations, T s , comprising alkoxide, fluoride, hydroxide, oxide, sub-oxide, sulfonate, or a combination thereof.

13. The method of claim 1 , wherein the M n−1 X n (T s ) or M′ 2 M″ m X m+1 composition is formed by removing at least 90% the A atoms from a MAX-phase composition having an empirical formula of M n+1 AX n or M′ 2 M″ m AX m+1 , respectively;
wherein M is at least one Group 3, 4, 5, 6, or 7 metal,
wherein A is an A-group element;
each X is C, N, or a combination thereof; and
n=1, 2, or 3.

14. The method of claim 13 , wherein removing the A atoms is done in aqueous media.

15. The method of claim 13 , wherein M is at least one of Hf, Cr, Mn, Mo, Nb, Sc, Ta, Ti, V, W, or Zr.

16. The method of claim 13 , wherein A is at least one of Al, As, Ga, Ge, In, P, Pb, S, or Sn.

17. The method of claim 13 , wherein the A atoms are removed by a process comprising a treatment with a fluorine-containing acid.

18. The method of claim 17 , wherein the fluorine-containing acid is aqueous hydrofluoric acid.

19. The method of claim 17 , wherein the fluorine-containing acid comprises:
(a) aqueous ammonium hydrogen fluoride (NH 4 F.HF);
(b) an alkali metal bifluoride salt (i.e., QHF 2 , where Q is Li, Na, or K), or a combination thereof; or
(c) at least one fluoride salt in the presence of at least one mineral acid that is stronger than HF; or
(d) a combination of two or more of (a)-(c).

20. The method of claim 19 , wherein the fluorine-containing acid is derived from lithium fluoride and an aqueous mineral acid that is stronger than HF.

21. A method comprising,
(a) applying a MXene dispersion onto a substrate surface, said MXene dispersion comprising at least one type of MXene platelets dispersed in a solvent and
(b) removing at least a portion of solvent so as to provide a coated film of at least one layer of MXene platelets oriented to be essentially coplanar with the substrate surface,
said MXene platelets comprising a M n+1 X n (T s ) composition having at least one layer, each layer having a first and second surface, each layer comprising
a substantially two-dimensional array of crystal cells
each crystal cell having an empirical formula of M n+1 X n , such that each X is positioned within an octahedral array of M,
wherein M is at least one Group 3, 4, 5, 6, or 7,
wherein each X is C, N, or a combination thereof and p 1 n=1, 2, or 3,
wherein at least one of said surfaces of the layers has surface terminations, T s , independently comprising alkoxide, alkyl, carboxylate, halide, hydroxide, hydride, oxide, sub-oxide, nitride, sub-nitride, sulfide, sulfonate, thiol, or a combination thereof;
said coated film being electrically conductive and exhibiting:
(i) a resistivity in a range of from about 0.01 to about 1000 micro-ohm-meters,
(ii) an ability to transmit at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, or at least about 95% of incident light of at least one wavelength in a range of from about 300 nm to about 2000 nm
(iii) a ratio of DC conductivity, measured in Siemens/meter, to light absorbance, (including visible light absorbance), measured as a decadic absorbance per meter, of at least 0.1 Siemens measured at at least one wavelength in the range of 300 to 2500 nm;
(iv) a value of the real dielectric permittivity less than negative one for wavelengths greate

Assignees

• Univ Drexel

Inventors

• Ghidiu Michael J
• Barsoum Michel W
• Gogotsi Yury
• Fafarman Aaron Thomas
• Dillon Andrew Devries

Classifications

• H10H20/833

  Transparent materials · CPC title

• H10F77/244 Primary

  made of transparent conductive layers, e.g. transparent conductive oxide [TCO] layers · CPC title

• C04B35/5607

  based on refractory metal carbides · CPC title

• C04B35/58007

  based on refractory metal nitrides · CPC title

• C04B2235/3203

  Lithium oxide or oxide-forming salts thereof · CPC title