Electrochemical process for production of graphene

Abstract

A process of producing graphene and/or graphite nanoplatelet structures by the electrochemical reduction of carbon oxide in an electrochemical cell is provided, wherein the cell includes (a) a negative electrode including a transition metal, transition metal-containing alloy, transition metal-containing oxide, transition metal containing ceramic, or a combination thereof; (b) a positive electrode; and (c) an electrolyte; wherein the process includes the step of passing a current between the electrodes in the presence of the carbon oxide.

1 . A process for producing graphene and/or graphite nanoplatelet structures having a thickness of less than 100 nm, the process comprising electrochemical reduction of carbon oxide in an electrochemical cell, wherein the cell includes:
 (a) a negative electrode including a transition metal, transition metal-containing alloy, transition metal-containing oxide, transition metal containing ceramic or combination thereof;   (b) a positive electrode; and   (c) an electrolyte;   wherein the process further includes the step of passing a current between the electrodes in the presence of the carbon oxide.   
     
     
         2 . A process according to  claim 1  wherein the process is for producing graphene, preferably wherein the graphene consists of from one to five graphene layers. 
     
     
         3 . The process of  claim 1  wherein the carbon oxide is carbon dioxide. 
     
     
         4 . The process of  claim 1  wherein the negative electrode includes copper, nickel-molybdenum alloy, molybdenum-titanium alloy or a combination thereof. 
     
     
         5 . A process according to  claim 4  wherein the negative electrode includes copper. 
     
     
         6 . The process of  claim 1  wherein the electrolyte is an ion-containing liquid, preferably selected from an ionic liquid, eutectic solvent, ionic solution or combination thereof, preferably wherein the ion-containing liquid is an ionic liquid or eutectic solvent. 
     
     
         7 . A process according to  claim 6  wherein the ion-containing liquid is an ionic liquid and wherein the ionic liquid includes a cation selected from the group consisting of 1-alkyl-3-methylimidazolium, 1-alkylpyridinium, N-methyl-N-alkylpyrrolidinium and ammonium and phosphonium ions; and an anion selected from the group consisting of a halide, tetrafluoroborate, hexafluorophosphate, bistriflimide, triflate, tosylate formate, alkylsulfate, alkylphosphate and glycolate. 
     
     
         8 . A process according to  claim 7  wherein the ionic liquid is selected from the group consisting of 1-butyl-3-methylimidazolium tetrafluoroborate (i.e. [bmim][BF 4 ]), 1-butyl-3-methylimidazolium hexafluorophosphate (i.e. [bmim][PF 6 ]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (i.e. [bmim][NTf 2 ]). 
     
     
         9 . A process according to  claim 6  wherein the ion-containing liquid is an eutectic solvent and wherein the eutectic solvent is selected from the group consisting of a mixture of ZnCl 2  and choline chloride, a mixture of CoCl 2 *6H 2 O and choline chloride, a mixture of choline chloride and urea, a mixture of ZnCl 2  and urea, a mixture of choline chloride and malonic acid, a mixture of choline chloride and phenol, and a mixture of choline chloride and glycerol. 
     
     
         10 . A process according to  claim 9  wherein the eutectic solvent is a mixture of choline chloride and urea. 
     
     
         11 . A process according to  claim 6  wherein the ion-containing liquid is an ionic solution and wherein the ionic solution includes an ammonium salt, an alkali metal bicarbonate, an alkali metal carbonate, an alkali metal halide or a combination thereof. 
     
     
         12 . A process according to  claim 11  wherein the ionic solution includes an ammonium salt, LiHCO 3 , NaHCO 3 , Na 2 CO 3 , K 2 CO 3 , a sodium halide, a potassium halide or a combination thereof. 
     
     
         13 . The process of  claim 1  wherein the temperature within the electrochemical cell is at least 10° C. and wherein the temperature within the electrochemical cell does not exceed 120° C. 
     
     
         14 . The process of  claim 1  further comprising the step of isolating the graphene and/or graphite nanoplatelet structures. 
     
     
         15 . The process of  claim 1  wherein the process further includes the step of exfoliating the graphene and/or graphite nanoplatelet structures.