Manganese-iridium composite oxide for water splitting catalyst, manganese-iridium composite oxide electrode material, and their production methods

Patent metadata

Field	Value
Publication number	US-12247302-B2
Application number	US-202117912686-A
Country	US
Kind code	B2
Filing date	Mar 19, 2021
Priority date	Mar 25, 2020
Publication date	Mar 11, 2025
Grant date	Mar 11, 2025

Abstract

To provide a manganese-iridium composite oxide, a manganese-iridium composite oxide and a manganese-iridium composite oxide electrode material, having high catalytic activity produced at low cost, to be used as an anode catalyst for oxygen evolution in water electrolysis, and their production methods.
A manganese-iridium composite oxide, which has an iridium metal content ratio (iridium/(manganese+iridium)) of 0.1 atomic % or more and 30 atomic % or less, and has interplanar spacings of at least 0.243±0.002 nm, 0.214±0.002 nm, 0.165±0.002 nm, 0.140±0.002 nm, and a manganese-iridium composite oxide electrode material comprising an electrically conductive substrate constituted by fibers at least part of which are covered with the above manganese-iridium composite oxide.

First claim

The invention claimed is:

1. A manganese-iridium composite oxide, which has an iridium metal content ratio (iridium/(manganese+iridium)) of 0.1 atomic % or more and 30 atomic % or less, and has interplanar spacings of at least 0.243±0.002 nm, 0.214±0.002 nm, 0.165±0.002 nm and 0.140±0.002 nm.

2. A manganese-iridium composite oxide electrode material comprising an electrically conductive substrate constituted by fibers at least part of which are covered with the manganese-iridium composite oxide as defined in claim 1 .

3. The manganese-iridium composite oxide electrode material according to claim 2 , wherein the amount of the covering manganese-iridium composite oxide is 0.1 mg/cm 2 or more and 25 mg/cm 2 or less per geometric area of the electrically conductive substrate.

4. The manganese-iridium composite oxide electrode material according to claim 2 , wherein the electrically conductive substrate is constituted by carbon, titanium, or platinum-covered titanium.

5. A laminate comprising the manganese-iridium composite oxide electrode material as defined in claim 2 , and a polymer electrolyte membrane.

6. An oxygen evolution electrode active material in water electrolysis, containing the manganese-iridium composite oxide as defined in claim 1 .

7. A water electrolysis apparatus, comprising the manganese-iridium composite oxide electrode material as defined in claim 2 .

8. A method for producing hydrogen, which comprises conducting water electrolysis using the manganese-iridium composite oxide electrode material as defined in claim 2 .

9. An oxygen evolution electrode comprising:
an oxygen evolution electrode active material, the oxygen evolution electrode active material comprising a manganese-iridium composite oxide; wherein
the manganese-iridium composite oxide has
an iridium metal content ratio (iridium/(manganese+iridium)) of 0.1 atomic % or more and 30 atomic % or less, and
interplanar spacings of at least 0.243±0.002 nm, 0.214±0.002 nm, 0.165±0.002 nm and 0.140±0.002 nm.

10. A laminate comprising the oxygen evolution electrode as defined in claim 9 , and a polymer electrolyte membrane.

11. A method for producing an manganese-iridium composite oxide electrode material comprising an electrically conductive substrate constituted by fibers at least part of which are covered with the manganese-iridium composite oxide as defined in claim 1 , which comprises electrodepositing the manganese-iridium composite oxide on the fibers constituting the electrically conductive substrate by electrolysis of a mixed solution containing sulfuric acid/manganese sulfate/iridium salt.

12. The method for producing the manganese-iridium composite oxide electrode material according to claim 11 , wherein a heat treatment is conducted.

13. The method for producing the manganese-iridium composite oxide electrode material according to claim 12 , wherein the heat treatment is conducted at from 180° C. to 500° C. for from 30 minutes to 8 hours.

14. The production method according to claim 11 , wherein the manganese-iridium composite oxide is electrodeposited in a deposition amount of from 0.1 mg/cm 2 or more and 25 mg/cm 2 or less per geometric area.

15. A method for producing an manganese-iridium composite oxide electrode material comprising an electrically conductive substrate constituted by fibers at least part of which are covered with the manganese-iridium composite oxide as defined in claim 1 , which comprises covering the fibers constituting the electrically conductive substrate with the manganese-iridium composite oxide by electrolysis with a sulfuric acid/manganese sulfate mixed solution and then by electrolysis with a mixed solution containing sulfuric acid/iridium salt.

Assignees

• Riken
• Tosoh Corp

Inventors

• Nakamura Ryuhei
• BONNET Nadege
• Kong Shuang
• Suetsugu Kazumasa

Classifications

• C25D9/08

  by cathodic processes · CPC title

• C25B1/04 Primary

  by electrolysis of water · CPC title

• C01P2006/40

  Electric properties · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• C01P2002/77

  by unit-cell parameters, atom positions or structure diagrams · CPC title