Photocatalyst production method, and hydrogen and oxygen production method using said photocatalyst

Patent metadata

Field	Value
Publication number	US-2024328012-A1
Application number	US-202418743226-A
Country	US
Kind code	A1
Filing date	Jun 14, 2024
Priority date	Dec 16, 2021
Publication date	Oct 3, 2024
Grant date	—

Abstract

Provided is a photocatalyst with significantly enhanced water splitting performance in YTOS or in a composition in which the yttrium element of YTOS has been replaced with another element. Also provided is a method for producing a photocatalyst that has a composition represented by the following general formula (I), the method including mixing, with a raw material of the photocatalyst, a flux component at a mass ratio of 0.01 times to 50 times, the flux component being composed of one or more chlorides and/or iodides of at least one selected from Li, Na, K, Rb, Mg, Ca, Sr, and Ba, and calcining a resultant product at 450° C. to 1050° C.:
M a Ti b O c S d   (I)

(where M is a combination of one or more selected from Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Y, a is a number of 1.7 to 2.3, b is a number of 2, c is a number of 4.7 to 5.3, and d is a number of 1.7 to 2.3).

First claim

1 . A method for producing a photocatalyst having a composition represented by the following general formula (I), comprising
mixing, with a raw material of the photocatalyst, a flux component at a mass ratio of 0.01 times to 50 times, the flux component being composed of one or more chlorides and/or iodides of at least one selected from Li, Na, K, Rb, Mg, Ca, Sr, and Ba, and calcining a resultant product at 450° C. to 1050° C.:
M a Ti b O c S d   (I)

(where M is a combination of one or more selected from Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Y, a is a number of 1.7 to 2.3, b is a number of 2, c is a number of 4.7 to 5.3, and d is a number of 1.7 to 2.3).

2 . The method according to claim 1 , wherein the acid washing is performed after the calcining.

3 . The method according to claim 1 , wherein the photocatalyst is for use in complete splitting of water.

4 . A method for producing hydrogen and oxygen, comprising using a fixed article obtained by fixing a photocatalyst which has been produced by the method according to claim 1 or using a molded article obtained by molding the photocatalyst, so as to generate the hydrogen and the oxygen.

5 . A method for preparing an electrode, comprising using a photocatalyst which has been produced by the method according to claim 1 .

6 . A method for producing hydrogen and oxygen, comprising using an electrode which has been prepared by the method according to claim 5 , so as to generate hydrogen and/or oxygen.

7 . A photocatalyst having a composition represented by the following general formula (I), wherein the photocatalyst generates hydrogen in an amount of 100 μmol or more per hour by irradiating the photocatalyst with light using a 300 W xenon lamp (λ>420 nm) in an aqueous methanol solution having a 10 volume % concentration or a 20 mmol/L Na 2 S—Na 2 SO 3 aqueous buffer solution:
M a Ti b O c S d   (I)

(where M is a combination of one or more selected from Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Y, a is a number of 1.7 to 2.3, b is a number of 2, c is a number of 4.7 to 5.3, and d is a number of 1.7 to 2.3).

8 . The photocatalyst according to claim 7 , wherein the photocatalyst is for use in complete splitting of water.

9 . A device which produces hydrogen and oxygen, wherein the device uses a fixed article obtained by fixing the photocatalyst according to claim 7 or a molded article obtained by molding the photocatalyst, so as to generate the hydrogen and the oxygen.

10 . An electrode prepared by using the photocatalyst according to claim 7 .

11 . A device which produces hydrogen and oxygen, wherein the device uses the electrode according to claim 10 so as to generate hydrogen and/or oxygen.

12 . A photocatalyst having a composition represented by the following general formula (I), wherein a surface elemental composition ratio of S to Ti (S/Ti) as obtained by XPS measurement is in a range of 0.50 to 1.08:
M a Ti b O c S d   (I)
(where M is a combination of one or more selected from Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Y, a is a number of 1.7 to 2.3, b is a number of 2, c is a number of 4.7 to 5.3, and d is a number of 1.7 to 2.3).

13 . The photocatalyst according to claim 12 , wherein the surface elemental composition ratio of S to Ti (S/Ti) as obtained by the XPS measurement is 0.50 to 0.95.

14 . The photocatalyst according to claim 12 , wherein the surface elemental composition ratio of S to Ti (S/Ti) as obtained by the XPS measurement is 0.80 to 0.95.

15 . The photocatalyst according to claim 12 , wherein the photocatalyst is for use in complete splitting of water.

16 . A device which produces hydrogen and oxygen, wherein the device uses a fixed article obtained by fixing the photocatalyst according to claim 12 or a molded article obtained by molding the photocatalyst, so as to generate the hydrogen and the oxygen.

17 . An electrode prepared by using the photocatalyst according to claim 12 .

18 . A device which produces hydrogen and oxygen, wherein the device uses the electrode according to claim 17 so as to generate hydrogen and/or oxygen.

Assignees

• Mitsubishi Chem Corp
• Univ Shinshu
• Japan Tech Research Association Of Artificial Photosynthetic Chemical Process

Inventors

• Yoshida Hiroaki
• Tsutsuminai Susumu
• Kariya Nobuko
• Domen Kazunari
• Hisatomi Takashi
• Lin Lihua
• Tao Xiaoping
• Liang Xizhuang

Classifications

• B01J2235/30

  Scanning electron microscopy; Transmission electron microscopy · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J2235/00

  Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties · CPC title

• B01J19/127

  Sunlight; Visible light · CPC title

• C25B11/087 Primary

  Photocatalytic compound · CPC title