Co3O4@IrOx catalyst, its preparation method and application

Abstract

This invention discloses a Co 3 O 4 @IrO x catalyst, its preparation method, and its applications, belonging to the technical field of catalyst materials for hydrogen production through water electrolysis. The  preparation  method  of the Co 3 O 4 @IrO x catalyst is as follows: using ZIF-67 as the core, adding a quaternary ammonium salt surfactant and an imidazole organic ligand, and reacting it with a zinc source to obtain a ZIF-67@ZIF-8 core-shell material; coating it on carbon paper to obtain a ZIF-67@ZIF-8 electrode sheet; pyrolyzing it to obtain a Co 3 O 4 @defective ZIF-8 electrode sheet; using a standard three-electrode system, with the Co 3 O 4 @defective ZIF-8 electrode sheet as the working electrode, performing pulsed potential etching in potassium hydroxide solution to obtain a Co 3 O 4 @vacancy-type ZIF-8 electrode sheet; and electrochemically depositing it in an iridium-containing potassium hydroxide solution to obtain the Co 3 O 4 @IrO x catalyst. The Co 3 O 4 @IrO x catalyst exhibits excellent hydrogen production capacity through water electrolysis.

What is claimed is: 
     
         1 . A method for preparing a Co 3 O 4 @IrO x  catalyst, comprising the following steps:  
       using ZIF-67 as the core, adding a quaternary ammonium salt surfactant and an imidazole organic ligand to coordinate with a zinc source to prepare a ZIF-67@ZIF-8 core-shell material; 
       coating the ZIF-67@ZIF-8 core-shell material onto carbon paper to prepare a ZIF-67@ZIF-8 electrode sheet;  
       pyrolyzing the ZIF-67@ZIF-8 electrode sheet at 300 ℃~400 ℃ in an air atmosphere; wherein, during the pyrolysis process, ZIF-67 collapses into Co 3 O 4 , yielding a Co 3 O 4 @defect-type ZIF-8 electrode sheet;  
       using a standard three-electrode system, with a carbon rod as a counter electrode, an Hg/HgO electrode as a reference electrode, and a Co 3 O 4 @defective ZIF-8 electrode sheet as a working electrode, subjecting the Co 3 O 4 @defective ZIF-8 electrode sheet to pulsed potential etching in potassium hydroxide solution, wherein, during the pulsed potential etching process, zinc ions on the surface of the Co 3 O 4 @defective ZIF-8 are etched away, resulting in a Co 3 O 4 @vacancy-type ZIF-8 electrode sheet; 
       using a standard three-electrode system, with a carbon rod as a counter electrode, an Hg/HgO electrode is used as a reference electrode, and the Co 3 O 4 @defective ZIF-8 electrode sheet as the working electrode, depositing Iridium onto the zinc ion vacancies of the Co 3 O 4 @vacancy-type ZIF-8 electrode sheet via electrochemical deposition in an iridium-containing potassium hydroxide solution, yielding the Co 3 O 4 @IrO x  catalyst.  
     
     
         2 . The method for preparing a Co 3 O 4 @IrO x  catalyst according to  claim 1 , characterized in that, during the pulsed potential etching process, short pulses at the cathode potential and anode potential are repeated, with the cathode potential at -2V for 1-2 seconds and the anode potential at 2V for 1-2 seconds, repeated 150 times as one activation cycle;  
       wherein the activation cycle is carried out 3-4 times.  
     
     
         3 . The method for preparing a Co 3 O 4 @IrO x  catalyst according to  claim 1 , characterized in that, during the electrochemical deposition process, short pulses at the cathode potential and anode potential are repeated, with the cathode potential at -6V for 1-2 seconds and the anode potential at 6V for 1-2 seconds, repeated 500 times as one activation cycle;  
       wherein the activation cycle is carried out 5-10. times.  
     
     
         4 . The method for preparing a Co 3 O 4 @IrO x  catalyst according to  claim 1 , characterized in that, in the iridium-containing potassium hydroxide solution, the concentration of iridium is 100 μmol/L.  
     
     
         5 . The method for preparing a Co 3 O 4 @IrO x  catalyst according to  claim 1 , characterized in that the pyrolysis time is 0.5 h.  
     
     
         6 . The method for preparing a Co 3 O 4 @IrO x  catalyst according to  claim 1 , characterized in that the mass ratio of the quaternary ammonium salt surfactant to the imidazole organic ligand is 15:1135~1136;  
       wherein the mass ratio of the quaternary ammonium salt surfactant to the zinc source is 15:72~73.  
     
     
         7 . The method for preparing a Co 3 O 4 @IrO x  catalyst according to  claim 1 , characterized in that the ratio of ZIF-67 to the quaternary ammonium salt surfactant is 6.9~7.4:15.  
     
     
         8 . The method for preparing a Co 3 O 4 @IrO x  catalyst according to  claim 1 , characterized in that the quaternary ammonium salt surfactant is hexadecyltrimethylammonium bromide and the imidazole organic ligand is 2-methylimidazole.  
     
     
         9 . A Co 3 O 4 @IrO x  catalyst prepared by the method according to  claim 1 . 
     
     
         10 . An application of the Co 3 O 4 @IrO x  catalyst according to  claim 9  in the electrocatalysis of oxygen evolution.