Process for producing dispersible and conductive nano graphene platelets from non-oxidized graphitic materials

1. A process for producing a dispersible nano graphene platelet (NGP) material, said process comprising:

(a) preparing a pristine NGP material from a graphitic material, wherein said pristine NGP material is obtained from a process comprising a procedure selected from:

a. intercalating said graphitic material with a non-oxidizing agent, followed by a thermal or chemical exfoliation treatment in a non-oxidizing environment;

b. subjecting said graphitic material to a supercritical fluid environment for inter-graphene layer penetration and exfoliation;

c. dispersing said graphitic material in a powder form to an aqueous solution containing a surfactant or dispersing agent to obtain a suspension and subjecting said suspension to direct ultrasonication; or a combination thereof; and

(b) subjecting said pristine NGP material to an oxidation treatment to obtain said dispersible NGP material, wherein said NGP material has an oxygen content in the range from approximately 5 to 25% by weight without any chemical reduction procedure.

2. The process as set forth in claim 1 wherein said dispersible NGP has an oxygen content in the range of approximately 5% to 20% by weight inclusive.

3. The process as set forth in claim 1 wherein said oxidation treatment comprises subjecting said pristine NGP material to an oxidizing agent selected from ozone, sulfonic vapor (SO 3 ), an oxygen-containing gas, hydrogen peroxide vapor, nitric acid vapor, or a combination thereof.

4. The process as set forth in claim 1 wherein said oxidation treatment comprises subjecting said pristine NGP material to an oxidizing agent in a hydrogen-containing environment.

5. The process as set forth in claim 1 wherein said graphitic material is selected from the group consisting of natural graphite, artificial graphite, graphite oxide, graphite fluoride, graphite fiber, carbon fiber, carbon nano-fiber, carbon nano-tube, mesophase carbon micro-bead (MCMB) or carbonaceous micro-sphere (CMS), soft carbon, hard carbon, and combinations thereof.

6. The process as set forth in claim 1 wherein said pristine NGP material is obtained from a process comprising dispersing said graphitic material in a powder form to an aqueous solution containing a surfactant or dispersing agent to obtain a suspension and subjecting said suspension to direct ultrasonication for a period of time sufficient to produce said pristine NGP material.

7. The process as set forth in claim 6 , further comprising a step of adding an acid, an oxidizer, or a combination thereof to said suspension for an oxidation treatment of said NGP material.

8. The process as set forth in claim 1 , wherein said oxidation treatment comprises exposing said pristine NGP material to a liquid acid or oxidizer solution.

9. The process as set forth in claim 1 , wherein said oxidation treatment comprises exposing said pristine NGP material to a liquid acid and/or oxidizer selected from sulfuric acid, nitric acid, carboxylic acid, acetic acid, formic acid, sodium or potassium nitrate, potassium permanganate (KMnO 4 ), sodium or potassium chlorate, hydrogen peroxide (H 2 O 2 ), or a combination thereof.

10. The process as set forth in claim 1 wherein said dispersible nano graphene platelet material, when formed into a thin film with a thickness no greater than 100 nm, exhibits an electrical conductivity of at least 10 S/cm.

11. The process as set forth in claim 1 wherein said dispersible nano graphene platelet material, when formed into a thin film with a thickness no greater than 100 nm, exhibits an electrical conductivity of at least 100 S/cm.

12. The process as set forth in claim 1 wherein said dispersible nano graphene platelet material, when formed into a thin film with a thickness no greater than 100 nm, exhibits an electrical conductivity of at least 1,000 S/cm.

13. The process as set forth in claim 1 wherein said nano graphene material has a specific surface area of approximately from 300 m 2 /g to 2,600 m 2 /g.

14. The process as set forth in claim 1 wherein said nano graphene platelet material comprises single-layer graphene.

15. The process as set forth in claim 1 , further comprising a step of contacting the nano graphene platelet material obtained in step (b) with a reactant such that a functional group is added to a surface or edge of the nano graphene platelet material.

16. The process as set forth in claim 15 , wherein said functional group is selected from alkyl or aryl silane, alkyl or aralkyl group, hydroxyl group, carboxyl group, amine group, sulfonate group (—SO 3 H), aldehydic group, quinoidal, fluorocarbon, or a combination thereof.