Water splitting catalyst, and method for producing oxygen and hydrogen using the same

Patent metadata

Field	Value
Publication number	US-10077500-B2
Application number	US-201514670541-A
Country	US
Kind code	B2
Filing date	Mar 27, 2015
Priority date	Mar 27, 2014
Publication date	Sep 18, 2018
Grant date	Sep 18, 2018

Abstract

Provided is a catalyst that exhibits a high catalyst activity in a water oxidation reaction within a neutral range. A water splitting catalyst comprises at least one 3d-block transition metal element selected from manganese, iron, cobalt, nickel, and copper or a compound containing the element, and a base and/or a carbonate having a pKa of 8 or less.

First claim

What is claimed is:

1. A device for water splitting comprising:
an electrode;
a catalytic layer, disposed on the electrode, comprising at least one selected from the group consisting of oxides and hydroxides of 3d-block transition metal element selected from manganese, iron, nickel, and copper;

an electrolytic cell in which the electrode and
a base and/or a carbonate having a pKa of 8 or less are disposed, provided that the base and/or a carbonate is disposed out of the catalytic layer;
wherein the device has a higher current density at a certain potential for splitting water having a pH ranging from 6 to 8, compared with a current density at the certain potential for splitting water having the pH without the base and/or the carbonate;

the concentration of the base added into water in the electrolytic cell is 0.025 M to 2 M; and
the concentration of the carbonate added into water in the electrolytic cell is 0.01 M to 1 M.

2. The device according to claim 1 , wherein the catalytic layer comprises at least manganese dioxide.

3. The device according to claim 1 , wherein the catalytic layer comprises at least β-manganese dioxide.

4. The device according to claim 1 , wherein the base is a nitrogen-containing heterocyclic compound.

5. The device according to claim 1 , wherein the base is collidine.

6. A method for producing oxygen and hydrogen, comprising preparing an electrode having a catalytic layer thereon which comprises at least one selected from the group consisting of oxides and hydroxides of 3d-block transition metal element selected from manganese, iron, nickel, and copper; and
allowing water having a pKa of 8 or less to contact with the catalytic layer along with a base and/or a carbonate, thereby to split the water;
wherein the catalytic activity of the catalytic layer during splitting water having a pH of 6 to 8 is enhanced compared with the catalytic activity of the catalytic layer during splitting water having a pH of 6 to 8 without the base and/or the carbonate;
the concentration of the base added into the water in 0.025 M to 2 M; and
the concentration of the carbonate added into the water is 0.01 M to 1 M.

7. The method according to claim 6 , wherein the catalytic layer comprises at least manganese dioxide.

8. The method according to claim 6 , wherein the catalytic layer comprises at least β-manganese dioxide.

9. The method according to claim 6 , wherein the base is a nitrogen-containing heterocyclic compound.

10. The method according to claim 6 , wherein the base is collidine.

Assignees

• Riken

Inventors

• Nakamura Ryuhei
• Hashimoto Kazuhito
• Yamaguchi Akira
• Kakizaki Hirotaka
• Hayashi Toru

Classifications

• C25B1/04 Primary

  by electrolysis of water · CPC title

• C25B9/06

  Chemistry & Metallurgy · mapped topic

• C25B11/0452

  Chemistry & Metallurgy · mapped topic

• Y02E60/366

  Cross-Sectional Technologies · mapped topic

• C25B11/16

  Chemistry & Metallurgy · mapped topic