Process and Device for Water Electrolysis Comprising a Special Oxide Electrode Material

Abstract

The invention relates to a method for water electrolysis consisting in using an electrode containing at least one type of oxide material of general formula A 2−x−y A′ x A″ y M 1−z M′ z O 4+δ , wherein A is a lanthanide and/or alkaline and/or alkaline earth metal cation, A′ is at least one lanthanide and/or alkaline and/or alkaline earth metal cation, A″ is a cation gap, M is a transition metal element, M′ is at least one type of transition metal element, wherein said metal is such that 0<y<0.30, preferably 0<y≦0.20; −0 1≦δ<0 25, preferably 0≦δ<0.25, most preferably 0≦δ<0 10; 0≦x≦1 and 0≦z≦1 An associated device is also disclosed

1 . A process for electrolysis of water comprising the use of an electrode comprising at least one oxide material of the following general formula:  
       A 2−x−y A′ x A″ y M 1−z M′ z O 4+δ , where:  A is a metal cation belonging to the group formed by lanthanides and/or alkali metals and/or alkaline-earth metals;    A′ is at least one metal cation belonging to the group formed by lanthanides and/or alkali metals and/or alkaline-earth metals;    A″ is a cationic vacancy, that is to say a cation A and/or cation A′ vacancy;    M is a metal belonging to the group formed by metals of transition elements;    M′ is at least one metal belonging to the group formed by metals of transition elements;    said material being such that    0≦y≦0.30, preferably 0≦y≦0.20;    −0.1≦δ<0 25, preferably 0≦δ<0 25, more preferably 0≦δ<0.10;    0≦x≦1; and    0≦z≦1.    
   
   
       2 . The process as claimed in the preceding  claim 1 , wherein: 
 A and A′ are chosen independently from the group formed by lanthanum La, praseodymium Pt, strontium Sy, calcium Ca and neodymium Nd, preferably neodymium Nd, strontium Sr and calcium Ca, even more preferably neodymium Nd, and wherein:    M and Mt are chosen independently from the group formed by chromium Cr, manganese Mn, iron Fe, cobalt Co, nickel Ni and copper Cu, preferably nickel Ni and copper Cu, even more prefer ably nickel Ni.    
   
   
       3 . The process as claimed in  claim 1 , wherein: 
 A is chosen from the group formed by lanthanum La, praseodymium Pr, and neodymium Nd, preferably neodymium Nd; and    A is chosen from the group formed by strontium Sr and calcium Ca, preferably calcium Ca;    and wherein:    M is chosen from the group formed by chromium Cr, manganese Mn, iron Fe, cobalt Co, nickel Ni and copper Cu, preferably nickel Ni; and    M′ is chosen from the group formed by manganese Mn, iron Fe, copper Cu or cobalt Co, preferably copper Cu or manganese Mn.    
   
   
       4 . The process as claimed in  claim 1 , wherein said material has a crystallographic structure of the K 2 NiF 4  type.  
   
   
       5 . The process as claimed in  claim 1 , wherein said material possesses an oxygen surface exchange coefficient k greater than 1×10 −8  cm/s at 500° C. and greater than 2×10 −6  cm/s at 900° C. for oxygen.  
   
   
       6 . The process as claimed in  claim 1 , wherein said material possesses an electronic conductivity σ e  at least equal to 70 S/cm, preferably at least equal to 80 S/cm, even more preferably greater than 90 S/cm at 700° C.  
   
   
       7 . The process as claimed in  claim 1 , wherein said material possesses an oxygen diffusion coefficient greater than 1×10 −9  cm 2 /s at 500° C. and greater than 1×10 −7  cm 2 /s at 900° C.  
   
   
       8 . The process as claimed in  claim 1 , wherein said material possesses an oxygen surface exchange coefficient k greater than 1×10 −8  cm/s at 500° C. and greater than 2×10 −6  cm/s at 900° C. for oxygen, an electronic conductivity σ e  at least equal to 70 S/cm, preferably at least equal to 80 S/cm, even more preferably greater than 90 S/cm at 700° C. and an oxygen diffusion coefficient greater than 1×10 −9  cm 2 /s at 500° C. and greater than 1×10 −7  cm 2 /s at 900° C.  
   
   
       9 . The process as claimed in  claim 1 , wherein said material is such that 6 is not equal to 0, preferably 0<δ<0.25, even more preferably 0<δ<0.10.  
   
   
       10 . The process as claimed in  claim 1 , wherein said process is implemented at a temperature greater than or equal to 600° C.  
   
   
       11 . A water electrolyzer type device comprising at least one electrochemical cell comprising a solid electrolyte, a cathode and an anode, which comprises at least one oxide material of the following general formula:  
       A 2−x−y A′ x A″ y M 1−z M′ z O 4+δ , where:  A is a metal cation belonging to the group formed by lanthanides and/or alkali metals and/or alkaline-earth metals;    A′ is at least one metal cation belonging to the group formed by lanthanides and/or alkali metals and/or alkaline-earth metals;    A″ is a cationic vacancy, that is to say a cation A and/or cation A′ vacancy;    M is a metal belonging to the group formed by metals of transition elements;    M′ is at least one metal belonging to the group formed by metals of transition elements;    said material being such that    0<y<0.30, preferably 0<y≦0.20;    −0.1≦δ<0.25, preferably 0≦δ<0.25, more preferably 0≦δ<0.10;    0≦x≦1; and    0≦z≦1.