Graphene and the production of graphene

Abstract

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.

What is claimed is: 
     
         1 . A composition comprising:
 dehydrogenated graphite comprising a plurality of flakes having
 at least one flake in 10 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 de-hydrogenated 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 5% of sp 3  hybridized carbon sites of the composition are one or more of 
   a) functionalized with a non-hydrogen chemical group,   b) cross-linked with sp 3  hybridized carbon sites of another flake.   
     
     
         2 . The composition of  claim 1 , wherein more than 60% of μ-Raman spectra of the de-hydrogenated 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 de-hydrogenated graphite have the coefficient of determination value larger than 0.995. 
     
     
         4 . The composition of  claim 1 , wherein at least one flake in six has a size in excess of 10 square micrometers. 
     
     
         5 . The composition of  claim 1 , wherein at least one flake in ten 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 of the dehydrogenated graphite 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 de-hydrogenated graphite collected at 532 nm excitation with a resolution better than 1.8 reciprocal centimeters is larger than 20 reciprocal centimeters. 
     
     
         12 . A composition comprising:
 a reversibly hydrogenated graphite comprising a plurality of flakes having
 at least one flake in 10 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 100× 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, 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,   b) cross-linked with sp 3  hybridized carbon sites of another flake.   
     
     
         13 . The composition of  claim 12 , wherein more than 60% of μ-Raman spectra of the graphite have the coefficient of determination value larger than 0.99. 
     
     
         14 . The composition of  claim 13 , wherein more than 40% of the μ-Raman spectra of the graphite have the coefficient of determination value larger than 0.995. 
     
     
         15 . The composition of  claim 13 , wherein at least one flake in ten has a size in excess of 25 square micrometers. 
     
     
         16 . The composition of  claim 13 , wherein the average thickness is seven atomic layers or less. 
     
     
         17 . The composition of  claim 13 , 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 100× objective having a D/G area ratio above 0.5. 
     
     
         18 . The composition of  claim 13 , wherein the defect density is characteristic of at least 50% of the collected spectra having a D/G area ratio above 0.8. 
     
     
         19 . The composition of  claim 13 , wherein the defect density is characteristic of the average D/G area ratio being between 0.4 and 2. 
     
     
         20 . The composition of  claim 13 , wherein at least 60% of the defects are reversible hydrogenation of sp a -hybridized carbon sites away from the edges of the flakes. 
     
     
         21 . An apparatus for the expansion of the graphite to graphene with at least one container provided for receiving an electrolyte, at least one anode and at least one cathode, characterized in that the cathode contains diamond or consists thereof. 
     
     
         22 . The apparatus of  claim 21 , further comprising a separator which separates the anode from the cathode. 
     
     
         23 . The apparatus according to  claim 22 , characterized in that the separator is in contact with the surface of the anode or that the separator is diamond and/or polytetrafluoroethylene and/or Al 2 O 3  and/or ceramic and/or quartz and/or glass contains or consists thereof. 
     
     
         24 . The apparatus according to  claim 22 , further comprising a drive means with which the separator, and optionally the anode, are rotatable. 
     
     
         25 . The apparatus according to  claim 22 , characterized in that the separator, and optionally the anode are displaceably mounted, so that the distance between the cathode and the separator is changeable in operation of the apparatus. 
     
     
         26 . The apparatus according to  claim 21 , further comprising an electric voltage supply set up to apply a DC voltage of from about 5 V to about 60 V between the anode and cathode, or from about 15 V to about 30 V, wherein the voltage is optionally pulsed. 
     
     
         27 . The apparatus according to  claim 21 , further comprising a feed apparatus by which electrolyte and graphite particles can be fed as a dispersion into the at least one container and/or further comprising a discharge apparatus by which electrolyte and graphene flakes are dischargable from the at least one container as a dispersion.