Water Electrolyzers Employing Anion Exchange Membranes

Abstract

Water electrolyzers comprises an anode comprising a quantity of anode catalyst, a cathode comprising a quantity of cathode catalyst with an inlet for introducing a cathode reactant thereto, an anion-conducting polymer electrolyte membrane interposed between said anode and said cathode, and a source of electrical energy that applies a voltage between the anode and cathode. At least one of said anode catalyst or said cathode catalyst comprises a metal or metal alloy having a surface area of at least 12 m 2 /gm. Water electrolyzers preferably employ base metal catalysts and an anion-conducting polymeric membrane with a resistance below 0.3 ohm-cm 2 and a base metal catalyst with a surface area of at least 12 m 2 /mg.

What is claimed is: 
     
         1 . A water electrolyzer comprising:
 (a) an anode comprising a quantity of anode catalyst;   (b) a cathode comprising a quantity of cathode catalyst, said cathode having an inlet for introducing a cathode reactant thereto;   (c) an anion-conducting polymer electrolyte membrane interposed between said anode and said cathode; and   (d) a source of electrical energy that applies a voltage between the anode and cathode,   
       wherein at least one of said anode catalyst or said cathode catalyst comprises a metal or metal alloy having a surface area of at least 12 m 2 /gm. 
     
     
         2 . The water electrolyzer of  claim 1 , wherein said cathode catalyst comprises a base metal. 
     
     
         3 . The water electrolyzer of  claim 2 , wherein said cathode catalyst comprises a metal or metal alloy with a surface area of at least 20 m 2 /gm. 
     
     
         4 . The water electrolyzer of  claim 3 , wherein said cathode catalyst comprises a metal or metal alloy with a surface area of at least 30 m 2 /gm. 
     
     
         5 . The water electrolyzer of  claim 4 , wherein said cathode catalyst comprises a metal or metal alloy with a surface area of at least 50 m 2 /gm. 
     
     
         6 . The water electrolyzer of  claim 2 , wherein said cathode catalyst comprises nickel or a nickel alloy. 
     
     
         7 . The water electrolyzer of  claim 2 , wherein said cathode catalyst comprises a porous metal. 
     
     
         8 . The water electrolyzer of  claim 7 , wherein said cathode catalyst comprises a spongy metal. 
     
     
         9 . The water electrolyzer of  claim 8 , wherein said cathode catalyst comprises at least one of nickel sponge or Raney nickel. 
     
     
         10 . The water electrolyzer of  claim 2 , wherein said anion-conducting polymer electrolyte membrane has a resistance below 1 ohm-cm 2  in 1 M KOH at 60° C. 
     
     
         11 . The water electrolyzer of  claim 10 , wherein said anion-conducting polymer electrolyte membrane has a resistance below 0.3 ohm-cm 2  in 1 M KOH at 60° C. 
     
     
         13 . The water electrolyzer of  claim 10 , wherein said anion-conducting polymer electrolyte membrane has a resistance below 0.1 ohm-cm 2  in 1 M KOH at 60° C. 
     
     
         14 . The water electrolyzer of  claim 3 , wherein said cathode catalyst comprises a catalyst layer on at least one of:
 (a) said an anion-conducting polymer electrolyte membrane;   (b) a gas diffusion layer;   (c) a metal fiber paper; and   (d) a metal grid or screen.   
     
     
         15 . The water electrolyzer of  claim 14 , wherein said catalyst layer is no more than 80 nm thick. 
     
     
         16 . The water electrolyzer of  claim 15 , wherein said catalyst layer is no more than 60 nm thick. 
     
     
         17 . The water electrolyzer of  claim 15 , wherein said catalyst layer has a thickness of 15-20 nm. 
     
     
         18 . The water electrolyzer of  claim 1 , wherein said cathode reactant comprises water.