Continuous production of exfoliated 2D layered materials by compressive flow
Described herein are methods for continuous production of an exfoliated two-dimensional (2D) material comprising passing a 2D material mixture through a convergent-divergent nozzle, the 2D material mixture comprising a 2D layered material and a compressible fluid. The method of the present disclosure employs physical compression and expansion of a flow of high-pressure gases, leaving the 2D layered material largely defect free to produce an exfoliated 2D layered in a simple, continuous, and environmentally friendly manner.
1. A method for continuous production of an exfoliated two-dimensional (2D) material comprising
a) providing a 2D layered material;
b) providing a compressible fluid;
c) mixing the 2D layered material with the compressible fluid thereby forming a 2D material mixture; and
d) passing the 2D material mixture through a convergent-divergent nozzle to exfoliate the 2D layered material before the compressible fluid intercalates the 2D layered material.
2. The method of claim 1 wherein the 2D layered material comprises graphite, graphene, boron nitride (BN), single-layer BN, molybdenum disulfide (MoS 2 ), single-layer MoS 2 , or any combination thereof.
3. The method of claim 1 wherein the compressible fluid comprises air, nitrogen, carbon dioxide, helium, or any combination thereof.
4. The method of claim 1 wherein a concentration of the 2D layered material in the 2D material mixture is about 0.01 milligrams per milliliter (mg/mL) to about 0.4 mg/mL.
5. The method of claim 1 wherein the convergent-divergent nozzle comprises a de Laval nozzle, a valve, an orifice, a thin tube, or any combination thereof.
6. The method of claim 5 wherein a valve comprises a needle valve, a butterfly valve, a globe valve, a pinch valve, an adjustable flow valve, a one-way flow valve, or any combination thereof.
7. The method of claim 1 , wherein passing the 2D material mixture through the convergent-divergent nozzle comprises applying a pressure to the 2D material mixture of about 200 pounds per square inch (psi) to about 4000 psi.
8. The method of claim 1 wherein the 2D material mixture enters the convergent-divergent nozzle at a velocity less than the speed of sound in the compressible fluid.
9. The method of claim 1 wherein the 2D material mixture exits the convergent-divergent nozzle at a velocity greater than the speed of sound in the compressible fluid.
10. The method of claim 1 , wherein the convergent-divergent nozzle has a throat dimension of about 0.005 millimeters (mm) to about 0.5 mm.
11. The method of claim 1 wherein the convergent-divergent nozzle has an inlet or an outlet dimension of about 3 mm to about 10 mm.
12. The method of claim 1 wherein the convergent-divergent nozzle has a length of about 15 centimeters (cm) to about 60 cm.
13. The method of claim 1 wherein the convergent-divergent nozzle has at least one of a throat-to-inlet dimension ratio and a throat-to-outlet dimension ratio of about 15 to about 60.
14. The method of claim 1 wherein a percent of the 2D layered material that produces the exfoliated 2D material is about 50% to about 100%.
15. The method of claim 1 wherein the exfoliated 2D material comprises a plurality of flakes with an aspect ratio of about 10 to about 300.
16. The method of claim 1 wherein the exfoliated 2D material comprises a plurality of flakes with an average thickness of about 0.35 nanometers (nm) to about 10 nm.
17. The method of claim 1 wherein the exfoliated 2D material comprises a plurality of flakes with an average length of about 50 nm to about 1,600 nm.
18. The method of claim 1 wherein the exfoliated 2D material comprises a plurality of flakes comprising at most about 20 layers.
19. The method of claim 1 wherein the 2D material mixture further comprises a solvent.
20. The method of claim 1 further comprising centrifuging the exfoliated 2D material.
21. The method of claim 20 wherein the centrifuging is performed at a rate of about 700 revolutions per minute (rpm) to about 4,000 rpm.
22. The method of claim 20 wherein the centrifuging is performed for a period of time of about 2 minutes to about 180 minutes.
23. A method for continuous production of exfoliated two-dimensional (2D) material comprising:
a) providing a 2D layered material;
b) providing a continuous flow of compressible fluid;
c) feeding the 2D layered material into the continuous flow of compressible fluid thereby forming a continuous flow of a mixture of the 2D layered material and compressible fluid; and
d) passing the continuous flow of the mixture of the 2D layered material and compressible fluid through a convergent-divergent nozzle to exfoliate the 2D layered material before the compressible fluid intercalates the 2D layered material.