Production of nano-structures

• US 9,034,297 B2
• Filed: 06/07/2010
• Issued: 05/19/2015
• Est. Priority Date: 06/08/2006
• Status: Active Grant

• Current Assignee: Directa Plus S.p.A. (Directa Plus Plc)
• Original Assignee: Directa Plus S.p.A. (Directa Plus Plc)
• Inventors: Mercuri, Robert Angelo
• Primary Examiner(s): MCCRACKEN, DANIEL
• Application Number:
  US12/794,872
• Publication Number:
  US 20110300056A1
• Time in Patent Office: 1,807 Days
• Field of Search: 423/448
• US Class Current: 423/448
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 32/154 Preparation
• CPC Class Codes: C01B 32/16 Preparation
• CPC Class Codes: C01B 32/19 by exfoliation
• CPC Class Codes: C01B 32/225 Expansion; Exfoliation

Abstract

A process for the production of nano-structures is presented, involving providing a graphite flake comprising graphene layers; intercalating the graphite flake to form a graphite intercalation compound exhibiting Stage I, II or III intercalation; and exfoliating the graphite intercalation compound by exposing it to a temperature between about 1600° C. and about 2400° C. such that a plurality of individual graphene layers are separated from the graphite intercalation compound.

Claims

1. A process for production of nano-structures, comprising:

providing a graphite flake comprising graphene layers;

intercalating the graphite flake to form a graphite intercalation compound exhibiting Stage I, II or III intercalation;

exfoliating the graphite intercalation compound by exposing it to a temperature between about 1600°

C. and about 2400°

C., such that a plurality of individual graphene layers are separated from the graphite intercalation compound; and

passing the plurality of individual graphene layers directly into a liquid,

wherein the temperature between 1600°

C. and 2400°

C. is provided by a gas plasma.

2. The process of claim 1, wherein the graphite flake is intercalated with an intercalant comprising formic acid, acetic acid, water, or combinations thereof.

3. The process of claim 1, wherein the graphite intercalation compound is exposed to a supercritical fluid prior to exfoliation.

4. The process of claim 1, wherein the graphite intercalation compound is brought from a temperature at which it is stable to a temperature between 1600°

C. and 2400°

C. within a period of no more than about 1 second.

5. The process of claim 4, wherein the graphite intercalation compound is brought from a temperature at which it is stable to a temperature between 1600°

C. and 2400°

C. within a period of no more than about 0.5 second.

6. The process of claim 1, wherein exfoliation is accomplished by feeding the graphite intercalation compound into a reaction zone which includes a region where the temperature is at least about 2600°

C.

7. The process of claim 6, wherein exfoliation, occurs in a reducing gas environment.

8. The process of claim 7, wherein exfoliation occurs in a hydrogen environment.

9. The process of claim 1, wherein the liquid is suitable for an end use of the individual graphene layers, and wherein the individual graphene layers comprise one or more defect sites, said one or more defect sites being capable of accommodating substances associated with said end use of the individual graphene layers.

10. The process of claim 9, wherein said one or more defect sites adsorb said substances during said end use.

11. A process for production of nano-structures, comprising:

providing microcrystalline graphite having a purity of at least 90% comprising a graphite flake comprising graphene layers, which comprise a plurality of defect sites within the plane of the graphene structure;

intercalating the graphite flake to form a graphite intercalation compound exhibiting Stage I, II or III intercalation;

at least partially removing chemicals used for intercalation from the surface of the graphite intercalation compound in a drying process; and

exfoliating the graphite intercalation compound in a reducing gas environment by exposing it to a temperature between about 1600°

C. and about 2400°

C. such that a plurality of individual graphene layers have one or more active sites onto which reducing gas is adsorbed and are separated from the graphite intercalation compound.

12. The process of claim 11, further comprising passing the plurality of individual graphene layers into a liquid suitable for an end use of the individual graphene layers, wherein the one or more active sites are adapted to accommodate substances associated with said end use of the individual graphene layers.

13. The process of claim 12, wherein said one or more active sites adsorb said substances during said end use.

14. The process of claim 11, wherein the graphite flake is intercalated with an intercalant comprising formic acid, acetic acid, water, or combinations thereof.

15. The process of claim 11, wherein the graphite intercalation compound is exposed to a supercritical fluid prior to exfoliation.

16. The process of claim 11, wherein the temperature is generated by high frequency induction and the graphite intercalation compound is fed into a gas plasma.

17. The process of claim 11, wherein the graphite intercalation compound is brought from a temperature at which it is stable to a temperature between 1600°

C. and 2400°

C. within a period of no more than about 1 second.

18. The process of claim 11, wherein the graphite intercalation compound is brought from a temperature at which it is stable to a temperature between 1600°

C. and 2400°

C. within a period of no more than about 0.5 second.

19. The process of claim 11, wherein exfoliation is accomplished by feeding the graphite intercalation compound into a reaction zone which includes a region where the temperature is at least about 2600°

C.

20. The process of claim 11, wherein exfoliation occurs in a hydrogen environment.

21. The process of claim 11, wherein the drying process comprises centrifugal drying, freeze drying, or filter pressing.

22. The process of claim 11, further comprising drawing a vacuum on the exfoliating graphite and directing the exfoliated graphite by means of the drawn vacuum.

23. The process of claim 11, wherein the temperature between 1600°

C. and 2400°

C. is provided by a gas plasma.

24. A process for production of nano-structures, comprising:

providing a graphite flake comprising graphene layers;

intercalating the graphite flake to form a graphite intercalation compound exhibiting Stage I, II or III intercalation;

feeding the graphite intercalation compound through a reaction zone;

exfoliating the graphite intercalation compound by exposing it to a temperature between about 1600°

C. and about 2400°

C., such that a plurality of individual graphene layers are separated from the graphite intercalation compound;

keeping the graphene layers in an inert or protective environment; and

passing the plurality of individual graphene layers directly into a liquid.

25. The process of claim 24, wherein heat in the reaction zone is provided by a gas plasma.

26. A process for production of nano-structures, comprising:

providing microcrystalline graphite having a purity of at least about 90% comprising a graphite flake comprising graphene layers;

intercalating the graphite flake to form a graphite intercalation compound exhibiting Stage I, II or III intercalation;

exfoliating the graphite intercalation compound in an inert gas or a reducing gas environment by exposing it to a temperature between about 1600°

C. and about 2400°

C., such that a plurality of individual graphite layers are separated from the graphite intercalation compound;

drawing a vacuum on the exfoliating graphite;

directing the exfoliated graphite by means of the drawn vacuum; and

passing the plurality of individual graphene layers directly into a liquid.

27. The process of claim 26, wherein the temperature between 1600°

C. and 2400°

C. is provided by a gas plasma.