Electrochemical cells and methods for electrochemical conversion of carbon dioxide

Abstract

Some embodiments of the invention include electrochemical cells for converting carbon dioxide. In certain embodiments, the electrochemical cell comprises a cathode diffusion electrode, a catholyte solution, a cation exchange membrane, an anode gas diffusion electrode, and an anolyte solution. Other embodiments of the invention include methods for converting carbon dioxide comprising applying a voltage across the cathode gas diffusion electrode and the anode gas diffusion electrode of an embodiment of the electrochemical cell. In some embodiments, the conversion of carbon dioxide produces one or more —O—(O)CH from one or more —OH on certain compounds (e.g., formula (I)) in the catholyte solution. Additional embodiments of the invention are also disclosed herein.

1 . An electrochemical cell comprising
 a cathode gas diffusion electrode comprising a cathode catalyst and a cathode substrate,   optionally, a cathode mesh spacer,   a catholyte solution which is in contact with the cathode gas diffusion electrode,   a cation exchange membrane which is in contact with the catholyte solution,   an anode gas diffusion electrode which is in contact with the cation exchange membrane, and   an anolyte solution which is contact with the anode gas diffusion electrode; wherein   (i) the catholyte solution comprises
 (a) a compound of formula (I) 
   
       
         
           
           
               
               
           
         
         where R is C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 2 -C 12  alkynyl, C 2 -C 12  alkoxy, aryl, cycloalkyl, heteroaryl, or heterocyclyl, which C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 2 -C 12  alkynyl, C 2 -C 12  alkoxy, aryl, cycloalkyl, heteroaryl, or heterocyclyl is optionally substituted with one or more of halogen, hydroxy (—OH), methanoyl (—COH), carboxy (—CO 2 H), nitro (—NO 2 ),—NH 2 ,—N(CH 3 ) 2 , cyano (—CN), ethynyl (—CCH), propynyl, sulfo (—SO 3 H), morpholinyl,—CO-morpholin-4-yl,—C(O) NH 2 ,—C(O) N (CH 3 ) 2 , C 1 -C 3  alkyl, C 1 -C 3  perfluoronated alkyl,—CF 3 ,—OCF 3 , C 1 -C 3  alkoxy, or C 1 -C 8  alkyl substituted with 1, 2, or 3—OH,
 (b) less than 12 vol % of water, 
 (c) less than 20 mM of a strong acid, and 
 (d) a nonaqueous solvent which is different from the compound of formula I, and 
 
         (ii) the anolyte solution is an aqueous solution with a pH from 0.1 to 3.5. 
       
     
     
         2 . The electrochemical cell of  claim 1 , wherein the cathode gas diffusion electrode comprises Pb, SnO, Bi metal, Zn, Pd, or Bi 2 O 3 , or an alloy thereof, or carbon paper, carbon fibers, glassy carbon, carbon nanofibers, carbon nanotubes, graphene, metallic foam, or a combination thereof. 
     
     
         3 . The electrochemical cell of  claim 1 , wherein the cathode catalyst comprises Pb, SnO, Bi metal, Zn, Pd, or Bi 2 O 3 , or an alloy thereof, or a combination thereof. 
     
     
         4 . The electrochemical cell of  claim 1 , wherein the cathode substrate comprises carbon paper, carbon fibers, glassy carbon, carbon nanofibers, carbon nanotubes, graphene, metallic foam, or a combination thereof. 
     
     
         5 . The electrochemical cell of  claim 1 , wherein the electrochemical cell comprises the cathode mesh spacer, the cathode mesh spacer is in contact with the cathode gas diffusion electrode, the cathode mesh spacer is in contact with the catholyte, and the cathode gas diffusion electrode is in contact with the catholyte. 
     
     
         6 . The electrochemical cell of  claim 1 , wherein R is C 1 -C 12  alkyl, C 2 -C 12  alkoxy, cycloalkyl, or heterocyclyl, which C 1 -C 12  alkyl, C 2 -C 12  alkoxy, cycloalkyl, or heterocyclyl is optionally substituted with one or more of halogen, hydroxy (—OH), methanoyl (—COH), carboxy (—CO 2 H), nitro (—NO 2 ),—NH 2 ,—N(CH 3 ) 2 , cyano (—CN), ethynyl (—CCH), propynyl, sulfo (—SO 3 H), morpholinyl,—CO-morpholin-4-yl,—C(O) NH 2 , —C(O) N (CH 3 ) 2 , C 1 -C 3  alkyl, C 1 -C 3  perfluoronated alkyl,—CF 3 ,—OCF 3 , C 1 -C 3  alkoxy, or C 1 -C 8  alkyl substituted with 1, 2, or 3—OH. 
     
     
         7 . The electrochemical cell of  claim 1 , wherein R is C 1 -C 12  alkyl, C 2 -C 12  alkoxy, cycloalkyl, or heterocyclyl, which C 1 -C 12  alkyl, C 2 -C 12  alkoxy, cycloalkyl, or heterocyclyl is optionally substituted with one or more of halogen, hydroxy (—OH), nitro (—NO 2 ),—NH 2 ,—N(CH 3 ) 2 , cyano (—CN), ethynyl (—CCH), propynyl, sulfo (—SO 3 H), morpholinyl, C 1 -C 3  alkyl, C 1 -C 3  perfluoronated alkyl,—CF 3 ,—OCF 3 , C 1 -C 3  alkoxy, or C 1 -C 8  alkyl substituted with 1, 2, or 3—OH. 
     
     
         8 . The electrochemical cell of  claim 1 , wherein R is C 1 -C 12  alkyl, which C 1 -C 12  alkyl is optionally substituted with one or more of halogen, hydroxy (—OH), nitro (—NO 2 ),—NH 2 ,—N (CH 3 ) 2 , cyano (—CN), ethynyl (—CCH), propynyl, sulfo (—SO 3 H), morpholinyl, C 1 -C 3  alkyl, C 1 -C 3  perfluoronated alkyl,—CF 3 ,—OCF 3 , C 1 -C 3  alkoxy, or C 1 -C 8  alkyl substituted with 1, 2, or 3—OH. 
     
     
         9 . The electrochemical cell of  claim 1 , wherein R is C 1 -C 6  alkyl, which C 1 -C 6  alkyl is optionally substituted with one or more of halogen, hydroxy (—OH),—NH 2 ,—N(CH 3 ) 2 , ethynyl (—CCH), propynyl, C 1 -C 3  alkyl, C 1 -C 3  perfluoronated alkyl,—CF 3 ,—OCF 3 , C 1 -C 3  alkoxy, or C 1 -C 8  alkyl substituted with 1, 2, or 3—OH. 
     
     
         10 . The electrochemical cell of  claim 1 , wherein formula (I) is methanol, ethanol, propenol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, or decanol. 
     
     
         11 . The electrochemical cell of  claim 1 , wherein the catholyte solution comprises from 5 to 30 vol % of the compound of formula (I). 
     
     
         12 . The electrochemical cell of  claim 1 , wherein the catholyte solution comprises less than 5 vol % of water. 
     
     
         13 . The electrochemical cell of  claim 1 , wherein the strong acid in the catholyte solution comprises hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, chloric acid, perchloric acid, or a combination thereof. 
     
     
         14 . The electrochemical cell of  claim 1 , wherein the concentration of the strong acid in the catholyte solution is from 2 to 18 mM. 
     
     
         15 . The electrochemical cell of  claim 1 , wherein the nonaqueous solvent in the catholyte solution comprises an aprotic solvent or propylene carbonate. 
     
     
         16 . The electrochemical cell of  claim 1 , wherein the catholyte solution comprises from 70 to 95 vol % of the nonaqueous solvent. 
     
     
         17 . The electrochemical cell of  claim 1 , wherein the surface tension of the catholyte solution is from 30 to 45 (mN/m). 
     
     
         18 . The electrochemical cell of  claim 1 , wherein the anode gas diffusion electrode comprises IrO 2 , RuO 2 , carbon paper, titanium, titanium mesh, or a combination thereof. 
     
     
         19 . The electrochemical cell of  claim 1 , wherein the anolyte solution has a pH from 0.5 to 3.0. 
     
     
         20 . The electrochemical cell of  claim 1 , wherein the anolyte solution comprises a strong acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, chloric acid, perchloric acid, or a combination thereof. 
     
     
         21 . The electrochemical cell of  claim 1 , wherein the catholyte further comprises a strong acid cation exchange medium. 
     
     
         22 . The electrochemical cell of  claim 1 , wherein the electrochemical cell further comprises an anion exchange membrane which is in contact with the cathode gas diffusion electrode and/or the optional cathode mesh spacer, and which is also in contact with the catholyte. 
     
     
         23 . The electrochemical cell of  claim 1 , wherein the electrochemical cell further comprises a catholyte inlet port, a catholyte outlet port, or both. 
     
     
         24 . The electrochemical cell of  claim 1 , wherein the electrochemical cell further comprises an anolyte inlet port, an anolyte outlet port, or both. 
     
     
         25 . The electrochemical cell of  claim 1 , wherein the electrochemical cell further comprises a gas inlet port and a gas outlet port, to permit a flow of a gas to be in contact with the cathode gas diffusion electrode. 
     
     
         26 . The electrochemical cell of  claim 1 , wherein a gas comprising CO 2  is in contact with the cathode gas diffusion electrode and the gas comprising CO 2  comprises other gases, inert gases, nitrogen, oxygen, argon, methane, water vapor, neon, carbon monoxide, flue gases, gases from the output of power plants, gases from the output of industrial plants, or a combination thereof. 
     
     
         27 . A method for converting CO 2 , the method comprising applying a voltage potential across the cathode gas diffusion electrode and the anode gas diffusion electrode of the electrochemical cell of  claim 1 , wherein the voltage is sufficient to convert CO 2  in a gas comprising CO 2  that is in contact with the cathode gas diffusion electrode to produce one or more 
       
         
           
           
               
               
           
         
       
       from one or more hydroxyls (—OH) of a compound of formula (I) in the catholyte solution. 
     
     
         28 . The method of  claim 27 , wherein the faradaic efficiency to convert CO 2  to produce one or more 
       
         
           
           
               
               
           
         
       
       from one or more hydroxyls (—OH) of a compound of formula (I) in the catholyte solution, is more than 30%. 
     
     
         29 . The method of  claim 27 , wherein the current density of the electrochemical cell is from 0.1 to 500 mA cm −2  or from 1 to 40 mA cm −2 .