Cobalt-copper nanoenabled electrodes

Abstract

A nanocomposite electrode includes a porous copper substrate, Co3O4 and/or Cu/Co(OH)x nanoparticles electrolytically deposited on the porous copper substrate. Fabricating the nanocomposite electrode includes contacting the porous copper substrate with a solution comprising cobalt, and electrodepositing the cobalt on the porous copper substrate to yield the nanocomposite electrode. Reducing nitrate to ammonia includes contacting the nanocomposite electrode with an aqueous solution comprising nitrate, and electrocatalytically reducing the nitrate to yield ammonia.

What is claimed is: 
     
         1 . A nanocomposite electrode comprising:
 a porous copper substrate; and   Co 3 O 4  and/or Cu/Co(OH) x  nanoparticles electrolytically deposited on the porous copper substrate.   
     
     
         2 . The electrode of  claim 1 , wherein an average size of the Co 3 O 4  and/or Cu/Co(OH) x  nanoparticles is in a range of 50 nm to 500 nm. 
     
     
         3 . The electrode of  claim 1 , wherein the porous copper substrate is a copper foam. 
     
     
         4 . The electrode of  claim 3 , wherein a porosity of the copper foam is in a range of 5 to 200 pores per inch. 
     
     
         5 . The electrode of  claim 1 , wherein the Co 3 O 4  and/or Cu/Co(OH) x  nanoparticles extend from pore surfaces of the porous copper substrate. 
     
     
         6 . The electrode of  claim 1 , wherein the Co 3 O 4  and/or Cu/Co(OH) x  nanoparticles are bound to the porous copper substrate. 
     
     
         7 . The electrode of  claim 1 , wherein a volume of the nanocomposite electrode is at least 0.1 cm 3 . 
     
     
         8 . A method of making a nanocomposite electrode, the method comprising:
 contacting a porous copper substrate with a solution comprising cobalt; and   electrodepositing the cobalt on the porous copper substrate to yield the nanocomposite electrode.   
     
     
         9 . The method of  claim 8 , wherein the porous copper substrate is a copper foam. 
     
     
         10 . The method of  claim 8 , wherein the solution comprises a cobalt salt in a range of 0.1 mol L −1  to 5 mol L −1 . 
     
     
         11 . The method of  claim 10 , wherein the solution comprises boric acid in a range of 0.1 mol L −1  to 5 mol L −1 . 
     
     
         12 . The method of  claim 11 , wherein the solution comprises sodium sulfate in a range of 0.01 mol L −1  to 1.0 mol L −1 . 
     
     
         13 . The method of  claim 8 , wherein electrodepositing the cobalt on the porous copper substrate comprises forming Co 3 O 4  and/or Cu/Co(OH) x  nanoparticles on surfaces of the porous copper substrate. 
     
     
         14 . The method of  claim 8 , wherein an average size of the Co 3 O 4  and/or Cu/Co(OH) x  nanoparticles is in a range of 50 nm to 500 nm. 
     
     
         15 . A method of reducing nitrate to ammonia, the method comprising:
 contacting the nanocomposite electrode of  claim 1  with an aqueous solution comprising nitrate; and   electrocatalytically reducing the nitrate to yield ammonia.   
     
     
         16 . The method of  claim 15 , further comprising electrocatalytically reducing the nitrate to yield nitrite, and electrocatalytically reducing the nitrite to yield ammonia. 
     
     
         17 . The method of  claim 16 , wherein electrocatalytically reducing the nitrate to yield nitrite is facilitated by copper in the porous copper substrate. 
     
     
         18 . The method of  claim 17 , wherein electrocatalytically reducing the nitrite to yield ammonia is facilitated by cobalt in the cobalt nanoparticles.