A modified catalyst for operating electrochemical carbon dioxide reduction in a non-alkali acidic medium and related techniques

Abstract

The disclosure relates to a carbon dioxide reduction catalyst for sustaining electroreduction of carbon dioxide into carbon products in a non-alkali acidic medium, the CO 2 R catalyst comprising: a catalytic layer being electrically conductive and comprising a metal catalyst favouring CO 2 R reactions, and an ionic layer being ionically conductive and deposited onto the catalytic layer, the ionic layer comprising an ionomer, with the ionomer comprising a cationic functional group being covalently bonded to a polymeric backbone of the ionomer and adsorbed on the surface of the catalytic layer.

1 . A carbon dioxide reduction (CO 2 R) catalyst for sustaining electroreduction of carbon dioxide (CO 2 ) into carbon products in a non-alkali acidic medium, the CO 2 R catalyst comprising:
 a catalytic layer being electrically conductive and comprising a metal catalyst favouring CO 2 R reactions, and   an ionic layer being ionically conductive and deposited onto the catalytic layer, the ionic layer comprising an ionomer, with the ionomer comprising a cationic functional group being covalently bonded to a polymeric backbone of the ionomer and adsorbed on the surface of the catalytic layer.   
     
     
         2 . (canceled) 
     
     
         3 . The CO 2 R catalyst of  claim 1 , wherein the metal catalyst is copper, nickel, cobalt, tin, bismuth, lead, indium, ruthenium, palladium, zinc, silver, gold, any alloys thereof or any combinations thereof. 
     
     
         4 . The CO 2 R catalyst of  claim 1 , wherein the cationic functional group is or comprises an imidazolium moiety. 
     
     
         5 . The CO 2 R catalyst of  claim 1 , wherein the cationic functional group is or comprises a benzimidazolium moiety. 
     
     
         6 . The CO 2 R catalyst of  claim 1 , wherein the cationic functional group is or comprises trimethylammonium, triethylammonium, tributylammonium, tripropylammonium, imidazole, 2-methyl-imidazole, 1,3-dimethyl-imidazole, 1-ethyl-imidazole, 1,3-diethyl-imidazole, 9-carbazole, N-ethyl-carbazole, pyridine, or any mixtures thereof. 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . The CO 2 R catalyst of  claim 1 , wherein the ionomer is an alkaline ionomer. 
     
     
         10 . (canceled) 
     
     
         11 . The CO 2 R catalyst of  claim 1 , wherein the ionic layer having an ion exchange capacity between 0.5 and 2.6 meq·g −1  in accordance with a loading of the cationic functional group, the ion exchange capacity being determined by the number of moles of exchanged ions to the dry weight of ionomer. 
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . (canceled) 
     
     
         15 . A modified cathode for operating electroreduction of carbon dioxide (CO 2 ) into carbon products in a non-alkali acidic medium, the modified cathode comprising:
 a gas diffusion layer, and   the CO 2 R catalyst as defined in  claim 1 , the catalytic layer of the CO 2 R catalyst being deposited onto the gas diffusion layer.   
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . (canceled) 
     
     
         19 . (canceled) 
     
     
         20 . A system for operating electroreduction of carbon dioxide (CO 2 ) into carbon products in a non-alkali acidic electrolyte, the system comprising:
 a cathodic compartment comprising:
 a reactant inlet configured to be supplied with a stream of gaseous CO 2 , 
 a modified cathode as defined in claim  15  converting CO 2  into carbon products according to CO 2 R reactions, 
 a product outlet to release a gas-liquid mixture comprising the carbon products; 
   an anodic compartment comprising:
 an anodic inlet configured to be supplied with a non-alkali acidic anolyte; 
 an anode converting H 2 O into O 2 , 
 an anodic outlet configured to release a mixture of O 2  and used non-alkali acidic electrolyte; and 
   a proton exchange membrane separating the cathodic compartment and the anodic compartment.   
     
     
         21 . The system of  claim 20 , wherein the system is a flow cell and the cathodic compartment further comprises
 a catholyte inlet configured to receive the non-alkali acidic electrolyte as a catholyte, and   a catholyte outlet to release used catholyte.   
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . (canceled) 
     
     
         25 . The system of  claim 20 , wherein the proton exchange membrane is or comprises perfluoro(2-(2-sulfonylethoxy)propyl vinyl ether)-tetrafluoroethylene copolymer, or tetrafluoroethylene-perfluoro(3-oxa-4-pentenesulfonic acid) copolymer. 
     
     
         26 . A process for electrochemically reducing CO 2  into carbon products, wherein the process comprises the following steps:
 (a) providing a system as defined in  claim 20 ,   (b) supplying the gas stream of CO 2  to the system,   (c) supplying the non-alkali acidic electrolyte to the system, and   (d) recovering the gas-liquid mixture comprising the carbon products.   
     
     
         27 . (canceled) 
     
     
         28 . The process of  claim 26 , comprising applying a full-cell potential sufficient to achieve a current density between 10 and 500 mA·cm −2 , as applied by electrochemical potentiostat stations. 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . The process of  claim 26 , wherein step (d) is performed with a C 2 + Faradaic Efficiency (FE) of at least 80% and a H 2  FE to at most 10%. 
     
     
         32 . A method for manufacturing a modified cathode configured for operating electroreduction of carbon dioxide (CO 2 ) into carbon products in a non-alkali acidic medium, wherein the method comprises the following steps:
 (a) providing a gas diffusion layer,   (b) depositing a metal catalyst favouring CO 2 R reactions onto the gas diffusion layer provided at step (a) to form an electrically conducting catalytic layer, and   (c) depositing an ionomer onto the electrically conducting catalytic layer formed at step (b) to form an ionically conducting layer, the ionomer comprising a cationic functional group bonded to a polymer backbone of the ionomer.   
     
     
         33 . (canceled) 
     
     
         34 . (canceled) 
     
     
         35 . (canceled) 
     
     
         36 . The method of  claim 32 , wherein step (c) comprises spraying a solution comprising the ionomer. 
     
     
         37 . (canceled) 
     
     
         38 . (canceled) 
     
     
         39 . The method of  claim 32 , wherein the method further comprises the step of preparing the solution comprising the cationic functional group. 
     
     
         40 . The method of  claim 39 , wherein the step of preparing the solution comprising the ionomer comprises dissolving an ionomer powder in a solvent. 
     
     
         41 . (canceled) 
     
     
         42 . The method of  claim 32 , the method further comprises the step of depositing a physical barrier layer onto the ionically conductive layer formed at step (c). 
     
     
         43 . The method of  claim 42 , wherein the step of depositing the physical barrier layer comprises spray coating a carbon-containing ink onto the ionically conductive layer formed at step (c). 
     
     
         44 . (canceled) 
     
     
         45 . (canceled)