Electrocatalyst for electrochemical conversion of carbon dioxide

Abstract

An electrocatalyst for the electrochemical conversion of carbon dioxide to hydrocarbons is provided. The electrocatalyst for the electrochemical conversion of carbon dioxide includes copper material supported on carbon nanotubes. The copper material may be pure copper, copper and ruthenium, copper and iron, or copper and palladium supported on the carbon nanotubes. The electrocatalyst is prepared by dissolving copper nitrate trihydrate in deionized water to form a salt solution. Carbon nanotubes are then added to the salt solution to form a suspension, which is then heated. A urea solution is added to the suspension to form the electrocatalyst in solution. The electrocatalyst is then removed from the solution. In addition to dissolving the copper nitrate trihydrate in the deionized water, either iron nitrate monohydrate, ruthenium chloride or palladium chloride may also be dissolved in the deionized water to form the salt solution.

We claim: 
     
         1 . An electrocatalyst for electrochemical conversion of carbon dioxide, comprising a copper catalyst material supported on carbon nanotubes. 
     
     
         2 . The electrocatalyst as recited in  claim 1 , wherein the copper catalyst material comprises pure copper, the pure copper forming 20 wt % of the electrocatalyst, the balance being the carbon nanotubes. 
     
     
         3 . The electrocatalyst as recited in  claim 1 , wherein the copper catalyst material comprises copper and ruthenium, the copper forming 20 wt % of the electrocatalyst, the ruthenium forming 20 wt % of the electrocatalyst, the balance being the carbon nanotubes. 
     
     
         4 . The electrocatalyst as recited in  claim 1 , wherein the copper catalyst material comprises copper and iron, the copper forming 20 wt % of the electrocatalyst, the iron forming 20 wt % of the electrocatalyst, the balance being the carbon nanotubes. 
     
     
         5 . The electrocatalyst as recited in  claim 1 , wherein the copper catalyst material comprises copper and palladium, the copper forming 20 wt % of the electrocatalyst, the palladium forming 20 wt % of the electrocatalyst, the balance being the carbon nanotubes. 
     
     
         6 . The electrocatalyst according to  claim 1 , wherein the electrocatalyst is a dry powder having particles in a size range of 3 nm to 60 nm. 
     
     
         7 . An electrode for electrochemical conversion of carbon dioxide, comprising a solid polymer electrolyte membrane having an electrocatalyst disposed on one side thereof, the electrocatalyst being nanoparticles of a catalyst having at least one metal supported on carbon nanotubes, the at least one metal being selected from the group consisting of pure copper, a mixture of copper and ruthenium, a mixture of copper and iron, and a mixture of copper and palladium. 
     
     
         8 . A method of making an electrocatalyst for electrochemical conversion of carbon dioxide, comprising the steps of:
 dissolving copper nitrate trihydrate in deionized water to form a salt solution;   adding carbon nanotubes to the salt solution to form a suspension;   heating the suspension;   adding a urea solution to the suspension to form an electrocatalyst in solution, the electrocatalyst comprising copper material supported on the carbon nanotubes; and   removing the electrocatalyst from the solution.   
     
     
         9 . The method of making an electrocatalyst as recited in  claim 8 , further comprising the step of sonicating the suspension for about one hour. 
     
     
         10 . The method of making an electrocatalyst as recited in  claim 10 , wherein the step of heating the suspension comprises heating the suspension to a temperature of about 90° C. with stirring. 
     
     
         11 . The method of making an electrocatalyst as recited in  claim 8 , further comprising the step of maintaining the mixture of the urea solution and the suspension at a temperature of about 90° C. for about eight hours. 
     
     
         12 . The method of making an electrocatalyst as recited in  claim 8 , wherein the step of removing the electrocatalyst from the solution comprises the steps of:
 cooling the solution to room temperature; and   centrifuging the solution to separate the electrocatalyst out of the solution.   
     
     
         13 . The method of making an electrocatalyst as recited in  claim 12 , wherein the step of removing the electrocatalyst from the solution further comprises the steps of washing and drying the electrocatalyst at a temperature of about 110° C. 
     
     
         14 . The method of making an electrocatalyst as recited in  claim 13 , wherein the step of removing the electrocatalyst from the solution further comprises the steps of calcining the washed and dried electrocatalyst at a temperature of about 450° C. for about four hours in an argon gas flow. 
     
     
         15 . The method of making an electrocatalyst as recited in  claim 14 , further comprising the step of reducing the calcined electrocatalyst at a rate of about 100 mL/min at a temperature of about 450° C. for about four hours in a gas flow of about 10% hydrogen in argon. 
     
     
         16 . The method of making an electrocatalyst for electrochemical conversion of carbon dioxide as recited in  claim 8 , further comprising the step of dissolving iron nitrate monohydrate in the deionized water to form the salt solution. 
     
     
         17 . The method of making an electrocatalyst for electrochemical conversion of carbon dioxide as recited in  claim 8 , further comprising the step of dissolving ruthenium chloride in the deionized water to form the salt solution. 
     
     
         18 . The method of making an electrocatalyst for electrochemical conversion of carbon dioxide as recited in  claim 8 , further comprising the step of dissolving palladium chloride in the deionized water to form the salt solution.