Carbon quantum dots and a method of making the same
The present invention is directed to a method of preparing a carbon quantum dot. The carbon quantum dot can be prepared from a carbon precursor, such as a fullerene, and a complex metal hydride. The present invention also discloses a carbon quantum dot made by reacting a carbon precursor with a complex metal hydride and a polymer containing a carbon quantum dot made by reacting a carbon precursor with a complex metal hydride.
1. A method for preparing carbon quantum dots, the method comprising:
reacting a carbon precursor with a complex metal hydride,
wherein the carbon precursor comprises a fullerene having 20 or more carbon atoms,
wherein the carbon quantum dots have a size of about 1 nm or greater to about 1000 nm or less.
2. The method according to claim 1 , wherein the fullerene has from 20 to 240 carbon atoms.
3. The method according to claim 2 , wherein the fullerene has from 60 to 240 carbon atoms.
4. The method according to claim 1 , wherein the fullerene comprises a C 60 fullerene.
5. The method according to claim 1 , wherein the weight ratio of the carbon precursor to the complex metal hydride is from 1:10 to 10:1.
6. The method according to claim 1 , wherein the complex metal hydride has the following formula
M x M′ y H n
wherein
M is an alkali metal cation or cation complex,
M′ is a metal or metalloid, and
x, y, and n are independently of one another, 1 or greater.
7. The method according to claim 6 , wherein M is an alkali metal cation and M′ is a Group IIIA metal or metalloid.
8. The method according to claim 6 , wherein M is Li or Na and M′ is Al or B.
9. The method according to claim 1 , wherein the complex metal hydride comprises LiAlH 4 , NaAlH 4 , KAlH 4 , NaBH 4 , KBH 4 , NaGaH 4 , LiGaH 4 , Mg(BH 4 ) 2 , Ca(BH 4 ) 2 , LiNH 2 , NH 3 BH 3 , Mg(NH 2 ) 2 .
10. The method according to claim 1 , wherein the complex metal hydride comprises LiBH 4 .
11. The method according to claim 1 , wherein the reaction occurs under nitrogen gas.
12. The method according to claim 1 , wherein the reaction occurs in the presence of an organic solvent.
13. The method according to claim 12 , wherein the organic solvent comprises tetrahydrofuran or benzene.
14. The method according to claim 1 , wherein the reaction occurs at a temperature of from about 25° C. to about 500° C.
15. The method according to claim 1 , further comprising annealing the carbon quantum dots at a temperature of from about 100° C. to about 500° C.
16. The method according to claim 15 , wherein the annealing is done in the presence of H 2 , H 2 O, NH 3 , H 2 S, or SO 2 .
17. The method according to claim 1 , wherein the carbon quantum dots have a hydrogen to carbon ratio of from 1:100 to 3:1.
18. The method according to claim 1 , wherein the carbon quantum dots have at least one heteroatom.
19. The method according to claim 18 , wherein the heteroatom comprises N, O, S, P, Si, Se, As, Ge, Gd, B, Sb, or Te.
20. The method according to claim 1 , wherein the carbon quantum dots are intercalated with a metal or metalloid selected from Group IA, Group IIA, and Group IIIA.
21. The method according to claim 20 , wherein the metal or metalloid comprises, Li, Na, B, Al, Ca, or Mg.
22. A carbon quantum dot made according to the method of claim 1 .
23. A polymer comprising the carbon quantum dot of claim 22 .