Producing graphene from coke using electrochemical exfoliation
A method of electrochemical exfoliation, may include: electrochemically exfoliating a parent material comprising coke, wherein the electrochemically exfoliating comprises introducing the parent material into a porous chamber, applying pressure to the porous chamber to thereby compress the parent material in the porous chamber, and applying a potential bias to the parent material while at least a portion of the parent material is in contact with an electrolyte solution to produce a mixture of exfoliated material and unexfoliated parent material, wherein the exfoliated material comprises exfoliated graphene; and separating at least a portion of the exfoliated material from the unexfoliated parent material.
1. A method of electrochemical exfoliation, comprising:
electrochemically exfoliating a parent material comprising coke, wherein the electrochemically exfoliating comprises introducing the parent material into a porous chamber, applying pressure along a length of the porous chamber to thereby compress the parent material in the porous chamber, wherein the pressure is applied by a weight from gravity to a first counter electrode and the porous chamber, wherein the first counter electrode is disposed between the weight and a lateral area of the porous chamber, and applying a potential bias to the parent material while at least a portion of the parent material is in contact with an electrolyte solution to produce a mixture of exfoliated material and unexfoliated parent material, wherein the exfoliated material comprises exfoliated graphene wherein the potential bias is applied to a pair of counter electrodes comprising the first counter electrode and a second counter electrode, wherein the second counter electrode is disposed underneath the porous chamber, wherein a working electrode is disposed in the porous chamber to contact the parent material; and
separating at least a portion of the exfoliated material from the unexfoliated parent material.
2. The method of claim 1 , wherein the coke comprises needle coke.
3. The method of claim 1 , wherein the potential bias is about 12 volts or greater.
4. The method of claim 1 , wherein the electrolyte solution comprises ammonium sulfate.
5. The method of claim 1 , wherein the separating at least a portion of the exfoliated material from the unexfoliated parent material comprises:
centrifuging the exfoliated material at conditions sufficient to separate a first sediment and a first supernatant comprising the exfoliated graphene; and
centrifuging the first supernatant at conditions sufficient to separate a second supernatant and a second sediment comprising the exfoliated graphene.
6. The method of claim 5 , wherein the exfoliated material is centrifuged at about 1000 RPM to about 3000 RPM for a period of about 5 minutes to about 15 minutes.
7. The method of claim 5 , wherein the first supernatant is centrifuged at RPM ranging from about 3000 RPM to about 6000 RPM for a period of about 15 minutes to about 25 minutes.
8. The method of claim 1 , wherein the separating at least a portion of the exfoliated material from the unexfoliated parent material comprises continuous flow centrifuging.
9. The method of claim 1 , further comprising annealing at least a portion of the exfoliated graphene at a temperature of about 200° C. to about 3000° C.
10. The method of claim 9 , wherein the step of annealing is performed for a period of about 30 minutes to about 24 hours.
11. The method of claim 9 , wherein the exfoliated graphene after annealing has a conductivity of about 50 S/m to about 10,000 S/m.
12. The method of claim 1 , further comprising contacting the parent material with a solvent and an acid prior to the step of electrochemically exfoliating.
13. The method of claim 12 , wherein the acid is nitric acid.
14. The method of claim 1 , wherein a molar ratio of carbon to oxygen of the exfoliated material is between about 1000:1 and about 3:1.