Graphene and the production of graphene
Compositions comprising hydrogenated and dehydrogenated graphite comprising a plurality of flakes. At least one flake in ten has a size in excess of ten square micrometers. For example, the flakes can have an average thickness of 10 atomic layers or less.
1. A composition comprising:
dehydrogenated graphite comprising a plurality of flakes having
at least one flake in 10 of the plurality of flakes having a size in excess of 10 square micrometers,
an average thickness of 10 atomic layers or less, and
a defect density characteristic of at least 50% of μ-Raman spectra of the dehydrogenated graphite collected at 532 nm excitation with a resolution better than 1.8 reciprocal centimeters having a D/G area ratio below 0.5, wherein the composition is a composite and at least 30% of sp 3 hybridized carbon sites of the composition are
cross-linked with sp 3 hybridized carbon sites of another flake of the plurality of flakes.
2. The composition of claim 1 , wherein more than 60% of μ-Raman spectra of the dehydrogenated graphite have the coefficient of determination value larger than 0.99.
3. The composition of claim 1 , wherein more than 40% of the μ-Raman spectra of the dehydrogenated graphite have the coefficient of determination value larger than 0.995.
4. The composition of claim 1 , wherein at least one flake in six of the plurality of flakes has a size in excess of 10 square micrometers.
5. The composition of claim 1 , wherein at least one flake in ten of the plurality of flakes has a size in excess of 25 square micrometers.
6. The composition of claim 1 , wherein the average thickness is seven atomic layers or less.
7. The composition of claim 1 , wherein the defect density is characteristic of at least 80% of the collected spectra having a D/G area ratio below 0.5.
8. The composition of claim 1 , wherein the defect density is characteristic of at least 50% of the collected spectra having a D/G area ratio below 0.2.
9. The composition of claim 1 , wherein the composition is a particulate powder of dehydrogenated graphite flakes.
10. The composition of claim 1 , wherein the plurality of the flakes are wrinkled, crumpled, or folded.
11. The composition of claim 1 , wherein the full width half maximum of the G peak in μ-Raman spectra of the dehydrogenated graphite collected at 532 nm excitation with a resolution better than 1.8 reciprocal centimeters is larger than 20 reciprocal centimeters.
12. The composition of claim 1 , wherein more than 1% of the plurality of flakes have a thickness of more than 10 atomic layers.
13. The composition of claim 12 , wherein more than 5% of the plurality of flakes have a thickness of more than 10 atomic layers.
14. The composition of claim 13 , wherein more than 10% of the plurality of flakes have a thickness of more than 10 atomic layers.
15. The composition of claim 1 , wherein the flakes of the plurality of flakes have an average surface area of more than 50 square micrometers.
16. The composition of claim 15 , wherein the plurality of flakes have an average surface area of more than 100 square micrometers.
17. A composition comprising:
a reversibly hydrogenated graphite comprising a plurality of flakes having
at least one flake in 10 of the plurality of flakes having a size in excess of 10 square micrometers,
a coefficient of determination value of 2D single peak fitting of μ-Raman spectra of the graphite after thermal treatment in inert atmosphere at 2 mbar and 800° C., collected at 532 nm excitation with a resolution better than 1.8 reciprocal centimeters, of larger than 0.99 for more than 50% of the spectra, and
a defect density characteristic of μ-Raman spectra of the hydrogenated graphite collected at 532 nm excitation with a resolution better than 1.8 reciprocal centimeters and an excitation power below 2 mW at the focus of an 100λ objective having an average D/G area ratio being between 0.2 and 4, wherein the majority of the defects are reversible hydrogenation of sp 3 -hybridized carbon sites away from the edges of the flakes of the plurality of flakes, wherein more than 60% of μ-Raman spectra of the graphite have the coefficient of determination value larger than 0.99, and wherein at least 60% of the defects are reversible hydrogenation of sp 3 -hybridized carbon sites away from the edges of the flakes of the plurality of flakes, and wherein the composition is a composite and at least 5% of sp 3 hybridized carbon sites of the composition are one or more of
a) functionalized with a non-hydrogen chemical group, or
b) cross-linked with sp 3 hybridized carbon sites of another flake of the plurality of flakes.
18. The composition of claim 17 , wherein more than 40% of the μ-Raman spectra of the graphite have the coefficient of determination value larger than 0.995.
19. The composition of claim 17 , wherein at least one flake in ten of the plurality of flakes has a size in excess of 25 square micrometers.
20. The composition of claim 17 , wherein the average thickness is seven atomic layers or less.
21. The composition of claim 17 , wherein the defect density is characteristic of at least 50% of the μ-Raman spectra collected at 532 nm excitation with a resolution better than 1.8 reciprocal centimeters and an excitation power below 2 mW at the focus of an 100λ objective having a D/G area ratio above 0.5.
22. The composition of claim 17 , wherein the defect density is characteristic of at least 50% of the collected spectra having a D/G area ratio above 0.8.
23. The composition of claim 17 , wherein the defect density is characteristic of the average D/G area ratio being between 0.4 and 2.
24. The composition of claim 17 , wherein the composition includes interstitial hydrogen and/or organic solvents or salts between the flakes of the plurality of flakes.