Production of Graphene

Abstract

An apparatus for large-scale production of graphene and graphene oxide is provided. The apparatus includes a first electrode, a second electrode, an electrobath, a power supply, and a module for filtering and separating the graphene products. Large amounts of graphene and graphene oxide can be produced rapidly using electrochemical exfoliation. High-quality graphene and graphene oxide can be produced under the room temperature in a simple and cost-effective way.

What is claimed is: 
     
         1 . An apparatus for producing at least one of graphene or graphene oxide, the apparatus comprising:
 a first electrode that includes graphite;   a second electrode;   a container that contains an electrolyte, in which the first and second electrodes are immersed in the electrolyte;   a power supply to supply bias voltages across the first and second electrodes to cause intercalation of graphite and exfoliation of graphene; and   a filtration module to separate the graphene from un-exfoliated graphite particles and collect the graphene.   
     
     
         2 . The apparatus of  claim 1  in which the first electrode comprises an electrode holder that holds graphite. 
     
     
         3 . The apparatus of  claim 2  in which the second electrode comprises an electrode holder that holds graphite. 
     
     
         4 . The apparatus of  claim 2  in which the electrode holder comprises a separation sieve having a pore size selected to allow the electrolyte to pass but prevent un-exfoliated graphite from passing. 
     
     
         5 . The apparatus of  claim 4  in which the separation sieve has a pore size selected to prevent a portion of the graphene from passing. 
     
     
         6 . The apparatus of  claim 1  in which the second electrode is made of metal. 
     
     
         7 . The apparatus of  claim 6  in which the metal comprises a precious metal that is resistant to acid. 
     
     
         8 . The apparatus of  claim 1  in which the second electrode is made of a mixture of graphite and a metal. 
     
     
         9 . The apparatus of  claim 1  in which the first electrode comprises at least one of natural graphite, highly-oriented pyrolytic graphite, pitch-based graphite, carbon fiber, coal, a material comprising graphite layers, or a material comprising graphite flakes. 
     
     
         10 . The apparatus of  claim 1  in which the first electrode comprises two sub-electrodes connected in parallel. 
     
     
         11 . The apparatus of  claim 10  in which the second electrode comprises two sub-electrodes connected in parallel. 
     
     
         12 . The apparatus of  claim 1  in which the electrolyte comprises at least one of hydrogen bromide, hydrochloric acid, or sulfuric acid. 
     
     
         13 . The apparatus of  claim 1 , comprising an air pump to pump the electrolyte through the filtration module. 
     
     
         14 . The apparatus of  claim 1  in which the filtration module comprises a microporous sieve and a filtration membrane. 
     
     
         15 . The apparatus of  claim 14  in which the microporous sieve has a size in a range from 18 mesh to 1250 mesh. 
     
     
         16 . The apparatus of  claim 14  in which the filtration membrane has a pore diameter in a range from 200 nm to 1,200 nm. 
     
     
         17 . The apparatus of  claim 1 , comprising a controller to control the power supply to provide a first bias voltage to cause intercalation and a second bias voltage to cause exfoliation. 
     
     
         18 . The apparatus of  claim 1 , comprising a controller to control the power supply to provide a first bias voltage during an intercalation step, and alternately provide a second bias voltage and a third bias voltage during an exfoliation step. 
     
     
         19 . The apparatus of  claim 18  in which the second bias voltage and the third bias voltage have opposite polarities. 
     
     
         20 . A method for producing graphene, comprising:
 immersing a first electrode and a second electrode in an electrolyte, the first electrode comprising graphite;   applying a first voltage across the first and second electrodes to cause intercalation of the graphite to form a graphite intercalation compound;   applying a second voltage across the first and second electrodes to exfoliate the graphite intercalation compound to produce at least one of graphene or graphene oxide;   filtering the electrolyte using a first filter that blocks un-exfoliated graphite particles and allows the at least one of graphene or graphene oxide to pass through; and   filtering the electrolyte using a second filter to collect the at least one of graphene or graphene oxide.   
     
     
         21 . The method of  claim 20  in which the first filter comprises a microporous sieve. 
     
     
         22 . The method of  claim 20  in which the second filter comprises a filtration membrane. 
     
     
         23 . The method of  claim 20  in which the second electrode comprises a holder that holds graphite or a mixture of graphite and metal. 
     
     
         24 . The method of  claim 20  in which the first electrode comprises at least one of natural graphite, highly-oriented pyrolytic graphite, pitch-based graphite, carbon fibers, coal, a material comprising graphite layers, or a material comprising graphite flakes. 
     
     
         25 . The method of  claim 20  in which the first electrode comprises two sub-electrodes connected in parallel. 
     
     
         26 . The method of  claim 25  in which the second electrode comprises two sub-electrodes connected in parallel. 
     
     
         27 . The method of  claim 20  in which the metal comprises a precious metal that is resistant to acid. 
     
     
         28 . The method of  claim 20  in which the electrolyte comprises at least one of hydrogen bromide, hydrochloric acid, or sulfuric acid. 
     
     
         29 . The method of  claim 20 , comprising an air pump to pump the electrolyte and cause the electrolyte to pass the first and second filters. 
     
     
         30 . The method of  claim 20  in which the first voltage is in a range from 0.5 V to 10 V. 
     
     
         31 . The method of  claim 20  in which the second voltage is in a range from 5 V to 220 V. 
     
     
         32 . The method of  claim 20  in which the voltage comprises a DC voltage. 
     
     
         33 . The method of  claim 20  in which the voltage comprises an AC voltage. 
     
     
         34 . The method of  claim 20  in which the first filter comprises a microporous sieve having a size in a range from 18 mesh to 1,250 mesh. 
     
     
         35 . The method of  claim 20  in which the second filter comprises a filtration membrane having a pore diameter in a range from 200 nm to 1,200 nm. 
     
     
         36 . The method of  claim 20 , comprising providing a third voltage during an exfoliation step, the third voltage having a polarity that is opposite to that of the second voltage. 
     
     
         37 . The method of  claim 36 , comprising during the exfoliation step, alternately providing the second voltage and the third voltage across the first and second electrodes.