Compositions comprising free-standing two-dimensional nanocrystals
The present invention is directed to methods of transferring urea from an aqueous solution comprising urea to a MXene composition, the method comprising contacting the aqueous solution comprising urea with the MXene composition for a time sufficient to form an intercalated MXene composition comprising urea.
1. A method of transferring urea from an aqueous solution to a MXene composition, the method comprising contacting an aqueous solution comprising urea with the MXene composition for a time sufficient to form an intercalated MXene composition comprising urea; wherein
the MXene composition comprises 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;
each X is C, N, or a combination thereof; and
n=1, 2, or 3; and wherein
the layers are characterized as having an average surface area; and
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 method of claim 1 , wherein both surfaces of each layer of the MXene composition has surface terminations comprising alkoxide, carboxylate, halide, hydroxide, hydride, oxide, sub-oxide, nitride, sub-nitride, sulfide, thiol, or a combination thereof.
3. The method of claim 1 , wherein M is at least one Group IVB, Group VB, or Group VIB metal.
4. The method of claim 1 , wherein M is Ti, and n is 1 or 2.
5. The method of claim 1 , wherein M n+1 X n comprises Sc 2 C, Sc 2 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, Ti 3 C 2 , Ti 3 N 2 , V 3 C 2 , Ta 3 C 2 , TaN 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 , or a combination thereof.
6. The method of claim 1 , wherein M n+1 X n comprises Ti 2 C, Ti 2 N, Ti 3 C 2 , Ti 3 N 2 , Ti 4 C 3 , Ti 4 N 3 , Ta 3 C 2 , Ta 3 N 2 , Ta 4 C 3 , or Ta 4 N 3 , or a combination thereof.
7. The method of claim 1 , wherein M n+1 X n comprises Ti 3 C 2 , TiNbC, Nb 2 C, Ti 3 CN, Ti 2 C, Ta 4 C 3 , or (V 1/2 Cr 1/2 ) 3 C 2 .
8. The method of claim 1 , wherein M n+1 X n is Ti 3 C 2 , TiNbC, Ti 3 CN, or Ti 2 C.
9. The method of claim 1 , wherein M n+1 X n is Ti 2 C or Ti 3 C 2 .
10. The method of claim 9 , wherein at least one of the surfaces of each layer has surface terminations comprising hydroxide, oxide, sub-oxide, or a combination thereof.
11. The method of claim 1 , wherein M is Ta, and n is 2 or 3.
12. The method of claim 1 , wherein the number of layers is in the range of 2 to about 50.
13. The method of claim 1 , 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 .