Methods of producing graphene quantum dots from coal and coke

Patent metadata

Field	Value
Publication number	US-9919927-B2
Application number	US-201414888301-A
Country	US
Kind code	B2
Filing date	May 2, 2014
Priority date	May 2, 2013
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

In some embodiments, the present disclosure pertains to methods of making graphene quantum dots from a carbon source (e.g., coal, coke, and combinations thereof) by exposing the carbon source to an oxidant. In some embodiments, the methods of the present disclosure further comprise a step of separating the formed graphene quantum dots from the oxidant. In some embodiments, the methods of the present disclosure further comprise a step of reducing the formed graphene quantum dots. In some embodiments, the methods of the present disclosure further comprise a step of enhancing a quantum yield of the graphene quantum dots. In further embodiments, the methods of the present disclosure also include a step of controlling the diameter of the formed graphene quantum dots by selecting the carbon source. In some embodiments, the formed graphene quantum dots comprise oxygen addends or amorphous carbon addends on their edges.

First claim

What is claimed is:

1. A method of making graphene quantum dots from a carbon source, wherein the method comprises:
exposing the carbon source to an oxidant,
wherein the carbon source is selected from the group consisting of coal, coke and combinations thereof,
wherein the exposing comprises stirring and heating the carbon source in the presence of the oxidant, and
wherein the exposing provides oxidative reaction conditions sufficient to result in formation of the graphene quantum dots from the carbon source.

2. The method of claim 1 , wherein the carbon source comprises coal, wherein the coal is selected from the group consisting of anthracite, bituminous coal, sub-bituminous coal, metamorphically altered bituminous coal, asphaltenes, asphalt, peat, lignite, steam coal, petrified oil, and combinations thereof.

3. The method of claim 1 , wherein the carbon source comprises coke.

4. The method of claim 1 , wherein the carbon source comprises bituminous coal.

5. The method of claim 1 , wherein the carbon source comprises anthracite.

6. The method of claim 1 , wherein the oxidant comprises an acid.

7. The method of claim 6 , wherein the acid is selected from the group consisting of sulfuric acid, nitric acid, phosphoric acid, hypophosphorous acid, fuming sulfuric acid, hydrochloric acid, oleum, chloro sulfonic acid, and combinations thereof.

8. The method of claim 1 , wherein the oxidant is a mixture of sulfuric acid and nitric acid.

9. The method of claim 1 , wherein the oxidant is selected from the group consisting of potassium permanganate, sodium permanganate, hypophosphorous acid, nitric acid, sulfuric acid, hydrogen peroxide, and combinations thereof.

10. The method of claim 1 , wherein the oxidant is a mixture of potassium permanganate, sulfuric acid, and hypophosphorous acid.

11. The method of claim 1 , wherein the exposing comprises sonicating the carbon source in presence of the oxidant.

12. The method of claim 1 , wherein the heating occurs at temperatures of at least about 100° C.

13. The method of claim 1 , wherein the heating occurs at temperatures ranging from about 100° C. to about 150° C.

14. The method of claim 1 , further comprising a step of separating the formed graphene quantum dots from the oxidant.

15. The method of claim 14 , wherein the separating comprises:
neutralizing a solution comprising the formed graphene quantum dots,
filtering the solution, and
dialyzing the solution.

16. The method of claim 1 , further comprising a step of enhancing a quantum yield of the graphene quantum dots.

17. The method of claim 16 , wherein the enhancing occurs by hydro thermal treatment of the graphene quantum dots, treatment of the graphene quantum dots with one or more bases, treatment of the graphene quantum dots with one or more hydroxides, treatment of the graphene quantum dots with one or more dopants, and combinations thereof.

18. The method of claim 16 , wherein the enhancing occurs by hydro thermal treatment of the graphene quantum dots.

19. The method of claim 1 , further comprising a step of reducing the formed graphene quantum dots.

20. The method of claim 19 , wherein the reducing comprises exposure of the formed graphene quantum dots to a reducing agent.

21. The method of claim 19 , wherein the reducing agent is selected from the group consisting of hydrazine, sodium borohydride, heat, light, sulfur, sodium sulfide, sodium hydrogen sulfide, and combinations thereof.

22. The method of claim 1 , wherein the formed graphene quantum dots have diameters ranging from about 1 nm to about 50 nm.

23. The method of claim 1 , wherein the carbon source is bituminous coal, and wherein the formed graphene quantum dots have diameters ranging from about 1 nm to about 5 nm.

24. The method of claim 1 , wherein the carbon source is anthracite, and wherein the formed graphene quantum dots have diameters ranging from about 10 nm to about 50 nm.

25. The method of claim 1 , wherein the carbon source is coke, and wherein the formed graphene quantum dots have diameters ranging from about 2 nm to about 10 nm.

26. The method of claim 1 , further comprising a step of controlling the diameter of the formed graphene quantum dots.

27. The method of claim 26 , wherein the controlling comprises selecting the carbon source.

28. The method of claim 27 , wherein the selected carbon source is bituminous coal, and wherein the formed graphene quantum dots have diameters ranging from about 1 nm to about 5 nm.

29. The method of claim 27 , wherein the selected carbon source is anthracite, and wherein the formed graphene quantum dots have diameters ranging from about 30 nm to about 50 nm.

30. The method of claim 27 , wherein the selected carbon source is coke, and wherein the formed graphene quantum dots have diameters ranging from about 2 nm to about 10 nm.

31. The method of claim 1 , wherein the formed graphene quantum dots have a crystalline hexagonal structure.

32. The method of claim 1 , wherein the formed graphene quantum dots have a single layer.

33. The method of claim 1 , wherein the formed graphene quantum dots have multiple layers.

34. The method of claim 33 , wherein the formed graphene quantum dots have from about two layers to about four layers.

35. The method of claim 1 , wherein the formed graphene quantum dots are functionalized with a plurality of functional groups.

36. The method of claim 35 , wherein the functional groups are selected from the group consisting of amorphous carbon, oxygen groups, carbonyl groups, carboxyl groups, esters, amines, amides, and combinations thereof.

37. The method of claim 35 , wherein the formed graphene quantum dots are edge functionalized with a plurality of functional groups.

38. The method of claim 37 , wherein the formed graphene quantum dots comprise oxygen addends on their edges.

39. The method of claim 37 , wherein the formed graphene quantum dots comprise amorphous carbon addends on their edges.

40. The method of claim 1 , wherein the formed graphene quantum dots are utilized in road stickers, road signs, coatings, clothing, paints, photographic processing materials, and combinations thereof.

Assignees

• Univ Rice William M

Inventors

• Tour James M
• Ye Ruquan
• Xiang Changsheng
• Lin Jian
• Peng Zhiwei
• Ceriotti Gabriel

Classifications

• Y10S977/774

  Exhibiting three-dimensional carrier confinement, e.g. quantum dots · CPC title

• C01B32/194

  After-treatment · CPC title

• C01B2204/32

  Size or surface area · CPC title

• C01B32/192

  starting from graphitic oxides · CPC title

• C01B2204/04

  Specific amount of layers or specific thickness · CPC title