Electrocatalyst for polymer electrolyte membrane (pem) water electrolysis, method of preparing same, pem water electrolysis electrode including same, and pem water electrolysis cell including same

Abstract

Proposed are an electrocatalyst for polymer electrolyte membrane (PEM) water electrolysis, the electrocatalyst including an iridium-based catalyst, wherein the iridium-based catalyst is a core-shell particle, the core contains iridium metal, and the shell contains an iridium tin composite oxide, a method of preparing the same, a PEM water electrolysis electrode including the electrocatalyst, and a PEM water electrolysis cell including the same. The electrocatalyst for PEM water electrolysis exhibits improved dispersibility and durability. In addition, the electrode, including such an electrocatalyst, exhibits improved oxygen evolution reaction (OER) activity.

What is claimed is: 
     
         1 . An electrocatalyst for polymer electrolyte membrane (PEM) water electrolysis, the electrocatalyst comprising an iridium-based catalyst,
 wherein the iridium-based catalyst is a core-shell particle,   the core contains iridium metal, and   the shell contains an iridium tin composite oxide.   
     
     
         2 . The electrocatalyst of  claim 1 , wherein the iridium metal is contained in the core in an amount in a range of 60 to 76 parts by weight based on 100 parts by weight of the entire electrocatalyst, and
 the iridium tin composite oxide is contained in the shell in an amount in a range of 24 to 40 parts by weight based on 100 parts by weight of the entire electrocatalyst.   
     
     
         3 . The electrocatalyst of  claim 1 , wherein the iridium tin composite oxide of the shell is a composite containing an iridium oxide and a tin oxide, and
 the tin oxide is contained in the composite in an amount in a range of 33 to 50 parts by weight based on 100 parts by weight of the iridium oxide.   
     
     
         4 . The electrocatalyst of  claim 1 , wherein tin is contained in the iridium tin composite oxide of the shell in an amount in a range of 33 to 50 moles based on 100 moles of iridium. 
     
     
         5 . The electrocatalyst of  claim 1 , further comprising a carrier,
 wherein the iridium-based catalyst is supported on the carrier.   
     
     
         6 . The electrocatalyst of  claim 5 , the iridium-based catalyst is contained in an amount in a range of 10 to 90 parts by weight based on 100 parts by weight of the carrier. 
     
     
         7 . The electrocatalyst of  claim 5 , the carrier further comprises a ceramic support. 
     
     
         8 . The electrocatalyst of  claim 7 , wherein the ceramic support is an antimony-doped tin oxide (Sb-doped tin oxide, ATO), alumina (Al 2 O 3 ), titania (TiO 2 ), zirconia (ZnO 2 ), or a combination thereof. 
     
     
         9 . The electrocatalyst of  claim 1 , wherein in X-ray diffraction (XRD) spectrum for the electrocatalyst, a multiplet peak appears at a diffraction angle 2θ in a range of 26.6° to 28°, and
 a singlet peak appears at a diffraction angle 2θ in a range of 40.5° to 40.9°. 
 
     
     
         10 . The electrocatalyst of  claim 1 , wherein the electrocatalyst comprises a compound represented by Chemical Formula 1 below, 
       
         
           
           
               
               
           
         
         where in Chemical Formula 1, 0.67≤x≤0.75. 
       
     
     
         11 . The electrocatalyst of  claim 10 , wherein the electrocatalyst is Ir 0.67 Sn 0.33 O 2 , Ir 0.75 S 0.25 O 2 , or a combination thereof. 
     
     
         12 . The electrocatalyst of  claim 1 , wherein the electrocatalyst has a median particle diameter in a range of 1 nm to 20 nm. 
     
     
         13 . A method of preparing the electrocatalyst of  claim 1 , the method comprising:
 dispersing a carrier in a polyol to prepare a carrier dispersion;   mixing an iridium precursor and a tin precursor with a polyol to obtain a precursor mixture;   mixing the carrier dispersion and the precursor mixture to prepare a first mixture;   performing a first heat treatment on the first mixture to prepare a catalyst precursor comprising iridium metal and tin oxide particles; and   performing a second heat treatment in an oxidizing gas atmosphere after washing and drying the catalyst precursor,   wherein the iridium precursor and the tin precursor are mixed at a molar ratio in a range of 1:0.33 to 0.50.   
     
     
         14 . The method of  claim 13 , wherein the first heat treatment is performed at a temperature in a range of 200° C. to 550° C. 
     
     
         15 . The method of  claim 13 , wherein the second heat treatment is performed at a higher temperature than the first heat treatment,
 the second heat treatment is performed at a temperature in a range of 350° C. to 600° C., and   the oxidizing gas atmosphere comprises an air atmosphere or an oxygen gas atmosphere.   
     
     
         16 . The method of  claim 13 , wherein the iridium and tin precursors are contained in a total amount in a range of 10 to 90 parts by weight based on 100 parts by weight of the carrier. 
     
     
         17 . A PEM water electrolysis electrode comprising the electrocatalyst of  claim 1 . 
     
     
         18 . A PEM water electrolysis cell comprising:
 a PEM; and   a PEM water electrolysis electrode being positioned on one surface of the PEM, the PEM water electrolysis electrode comprising the electrocatalyst of  claim 1 .   
     
     
         19 . The PEM water electrolysis cell of  claim 18 , wherein the electrode is an anode.