Metal enhanced transition metal oxide electrocatalysts for reduction of co2

Abstract

Disclosed is a technique for reducing CO 2 to oxalate utilizing a copper-free, nickel-enhanced electrocatalyst (such as a nickel-enhanced (Cr 2 O 3 ) 3 (Ga 2 O 3 ) electrocatalyst) that can be used for producing, e.g., 1-butanol, in exceedingly high yields. Disclosed herein are various synthetic methodologies for introducing nickel into the electrocatalysts, and described is the characterization, and optimization of the Ni enhanced electrocatalysts for the reduction of CO 2 to 1-butanol with a maximum faradaic efficiency ξ max of 64%, at an overpotential of 900 mV (−1.48 V vs Ag/AgCl), and having an onset overpotential of 320 mV. The product selectivity is potential dependent with other C 2+ products such as 3-hydroxybutanal, (ξ max 63%) at an overpotential of 890 mV (−1.4 V vs Ag/AgCl); acetic acid with ξ max 18% at an overpotential of 390 mV (−1.0 V vs Ag/AgCl); and acetone with ξ max 10% at an overpotential of 620 mV (−1.2 V).

What is claimed is: 
     
         1 . A system for reducing carbon dioxide to produce a desired reaction product, comprising:
 a container;   an aqueous solution within the container, the aqueous solution comprising an inorganic salt, and carbon dioxide;   a plurality of electrodes at least partially within the aqueous solution and separated from each other, including a first electrode comprising a metal enhanced transition metal oxide, wherein the metal enhanced transition metal oxide is free of copper; and   circuitry configured to provide a voltage to the plurality of electrodes.   
     
     
         2 . The system according to  claim 1 , wherein at least two of the plurality of electrodes are separated by a salt bridge. 
     
     
         3 . The system according to  claim 1 , wherein the metal enhanced transition metal oxide comprises nickel. 
     
     
         4 . The system according to  claim 3 , wherein the metal enhanced transition metal oxide comprises nickel enhanced (M1 2 O 3 ) x (M2 2 O 3 ) 4-x , where M1 and M2 are different metal oxides, and 0<x<4. 
     
     
         5 . The system according to  claim 4 , wherein M1 is Cr and M2 is Ga. 
     
     
         6 . The system according to  claim 1 , wherein aqueous solution further comprises a pH adjusting agent for adjusting the pH of the aqueous solution to fall within a target pH range. 
     
     
         7 . The system according to  claim 6 , wherein the target pH range is 0-7. 
     
     
         8 . The system according to  claim 7 , wherein the target pH range is 3.8-5.5. 
     
     
         9 . The system according to  claim 1 , wherein the voltage applied is 0V-10V. 
     
     
         10 . A method for reducing carbon dioxide to produce a desired compound, comprising:
 passing a predetermined electrical voltage across a plurality of electrodes at least partially within an aqueous solution, the plurality of electrodes including a first electrode comprising a metal enhanced transition metal oxide, wherein the metal enhanced transition metal oxide is free of copper, the aqueous solution comprising carbon dioxide; and   collecting at least some of the reaction product after a predetermined period of time, the reaction product comprising the desired compound.   
     
     
         11 . The method according to  claim 10 , wherein the metal enhanced transition metal oxide comprises nickel. 
     
     
         12 . The method according to  claim 11 , wherein the metal enhanced transition metal oxide comprises nickel enhanced (M1 2 O 3 ) x (M2 2 O 3 ) 4-x , where M1 and M2 are different metal oxides, and 0<x<4. 
     
     
         13 . The method according to  claim 12 , wherein M1 is Cr and M2 is Ga. 
     
     
         14 . The method according to  claim 10 , wherein aqueous solution further comprises a pH adjusting agent for adjusting the pH of the aqueous solution to fall within a target pH range. 
     
     
         15 . The method according to  claim 14 , wherein the target pH range is 0-7. 
     
     
         16 . The method according to  claim 15 , wherein the target pH range is 3.8-5.5. 
     
     
         17 . The method according to  claim 10 , wherein the voltage applied is 0V-10V. 
     
     
         18 . The method according to  claim 10 , wherein the voltage is configured to vary over time. 
     
     
         19 . The method according to  claim 10 , wherein the voltage is configured to remain substantially constant over time.