Water electrolysis system

Abstract

In a water electrolysis system having an anode catalyst layer containing anode catalyst and a cathode catalyst layer containing cathode catalyst tightly attached, respectively, to each surface of a solid polymer electrolyte membrane comprising a cation exchange membrane, wherein at least one catalyst layer of said anode catalyst layer and cathode catalyst layer comprises a porous structure of anode catalyst or cathode catalyst dispersed in fluorine resin containing resin, featuring the surface of the anode catalyst layer or the cathode catalyst layer being hydrophobized and the water contact angle with the surface of the anode catalyst layer or the cathode catalyst layer of said porous structure being 90 degrees or more, whereby the transfer of gas to the counter electrode can be significantly suppressed, gas purity and current efficiency be improved, and safety operation of the electrolysis system be secured, without a major change in configuration of the water electrolysis system.

1 . A water electrolysis system having an anode catalyst layer containing anode catalyst and a cathode catalyst layer containing cathode catalyst tightly attached, respectively, to each surface of a solid polymer electrolyte membrane comprising a cation exchange membrane, wherein at least one catalyst layer of said anode catalyst layer and cathode catalyst layer comprises a porous structure of anode catalyst or cathode catalyst dispersed in fluorine resin containing resin, featuring the surface of the anode catalyst layer or the cathode catalyst layer being hydrophobized and the water contact angle with the surface of the anode catalyst layer or the cathode catalyst layer of said porous structure being 90 degrees or more. 
   
   
       2 . A water electrolysis system according to  claim 1 , in which the fluorine resin containing resin used for said porous structure is polytetrafluoroethylene. 
   
   
       3 . A water electrolysis system according to  claim 1 , in which the catalyst layer comprising said porous structure is a cathode catalyst layer containing cathode catalyst. 
   
   
       4 . A water electrolysis system according to  claim 2 , in which said cathode catalyst layer comprises a porous structure of platinum or platinum-loaded carbon grain dispersed in fluorine resin containing resin. 
   
   
       5 . A water electrolysis system according to  claim 1 , in which the porous structure comprises a porous metal plate or a sintered sheet of metallic fiber having on its surface anode catalyst containing lead dioxide or iridium in said anode catalyst layer. 
   
   
       6 . A water electrolysis system according to  claim 3 , in which the catalyst layer comprising said porous structure has a layer coated with fluorine resin layer on the surface of said cathode catalyst layer.