Compositions comprising free-standing two-dimensional nanocrystals
The present invention is directed to compositions comprising at least one layer or at least two layers, each layer comprising a substantially two-dimensional array of crystal cells, having first and second surfaces, each crystal cell having the empirical formula of M n+1 X n , where M, X, and n are described in the specification, and devices incorporating these compositions.
1. A composition comprising at least one layer having first and second surfaces, each layer comprising:
a substantially two-dimensional array of crystal cells,
each crystal cell having the 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 IIIB, IVB, VB, or VIB metal or Mn;
each X is C, N, or a combination thereof; and
n=1, 2, or 3; and wherein
at least one of said surfaces of each layer has bound thereto surface terminations comprising alkoxide, carboxylate, halide, hydroxide, hydride, oxide, sub-oxide, nitride, sub-nitride, sulfide, thiol, or a combination thereof.
2. The composition of claim 1 , wherein both surfaces of each layer have surface terminations comprising alkoxide, carboxylate, halide, hydroxide, hydride, oxide, sub-oxide, nitride, sub-nitride, sulfide, thiol, or a combination thereof.
3. The composition of claim 1 , wherein M is at least one Group IVB, Group VB, or Group VIB metal or Mn.
4. The composition of claim 1 , wherein at least one of the surfaces of each layer has surface terminations comprising hydroxide, oxide, sub-oxide, or a combination thereof.
5. The composition of claim 1 , wherein M is Ti, and n is 1 or 2.
6. The composition of claim 1 , wherein X is carbon.
7. The composition of claim 1 , wherein M n+1 X n comprises Ti 3 C 2 , TiNbC, Ti 3 CN, or Ti 2 C.
8. The composition of claim 1 , wherein M n+1 X n comprises Ti 2 C or Ti 3 C 2 .
9. A stacked assembly of at least two layers, each layer having first and second surfaces, each layer comprising:
a substantially two-dimensional array of crystal cells,
each crystal cell having the 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 IIIB, IVB, VB, or VIB metal or Mn;
each X is C, N, or a combination thereof; and
n=1, 2, or 3;
wherein the layers are characterized as having an average surface area and an average interlayer distance; and wherein
at least one of said surfaces of each layer has bound thereto surface terminations comprising alkoxide, carboxylate, halide, hydroxide, hydride, oxide, sub-oxide, nitride, sub-nitride, sulfide, thiol, or a combination thereof.
10. The stacked assembly of claim 9 , wherein M n+1 X n comprises Ti 2 C or Ti 3 C 2 .
11. The stacked assembly of claim 9 , wherein M n+1 X n comprises Ti 2 C or Ti 3 C 2 .
12. The stacked assembly of claim 9 , wherein the number of layers is in the range of 2 to about 50.
13. The stacked assembly of claim 9 , wherein the average surface area of the layers is in the range of from about 100 nm 2 to about 10,000 nm 2 or from about 100 μm 2 to about 10,000 μm 2 .
14. The stacked assembly of claim 9 , further comprising atoms, ions, or both atoms and ions of lithium, sodium, potassium, magnesium, or a combination thereof intercalated between at least two of the layers.
15. The stacked assembly of claim 9 , wherein lithium atoms, lithium ions, or both lithium atoms and lithium ions are intercalated between at least some of the layers.
16. The stacked assembly of claim 9 , wherein the stacked assembly comprises a conductive or semiconductive outer surface.
17. The stacked assembly of claim 9 , wherein the stacked assembly comprises a conductive outer surface that exhibits a surface resistivity of less than about 50 micro-ohm-meters.
18. The stacked assembly of claim 9 having a form of a sheet or film form, wherein the sheet or film exhibits at least 50% optical transparency to at least one wavelength of light in a range of from about 250 nm to about 850 nm.
19. The stacked assembly of claim 9 , wherein the optical transparency is in a range of from about 70% to about 95%.
20. An energy-storing device or electrode comprising the stacked assembly of claim 9 .