Visible-light photocatalyst particles and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-9808791-B2
Application number	US-201314404561-A
Country	US
Kind code	B2
Filing date	May 29, 2013
Priority date	May 29, 2012
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

Disclosed is a visible light responsive photocatalyst that simultaneously realizes high crystallinity and refinement of primary particles. Also disclosed is a photocatalyst composed of secondary particles that have a high porosity and are aggregates of fine primary particles. Rhodium-doped strontium titanate that is a visible light responsive photocatalyst of the present invention has a primary particle diameter of not more than 70 nm and has a absorbance at a wavelength of 570 nm of not less than 0.6 and a absorbance at a wavelength of 1800 nm of not more than 0.7, each absorbance determining by measuring a diffuse reflection spectrum, the rhodium-doped strontium titanate having a high water-splitting activity as a photocatalyst.

First claim

The invention claimed is:

1. Rhodium-doped strontium titanate particles having a primary particle diameter of not more than 70 nm and having
an absorbance at a wavelength of 570 nm of not less than 0.6 and
an absorbance at a wavelength of 1800 nm of not more than 0.7,
each absorbance being determined by measuring a diffuse reflection spectrum, and
a molar ratio represented by M (rhodium)/M (titanium+rhodium) of 0.001 to 0.03.

2. The rhodium-doped strontium titanate particles according to claim 1 , wherein the primary particle diameter is not more than 50 nm.

3. The rhodium-doped strontium titanate particles according to claim 2 , wherein the primary particle diameter is not less than 30 nm.

4. The rhodium-doped strontium titanate particles according to claim 1 , wherein the absorbance at a wavelength of 570 nm is greater than or equal to 0.6 to less than 0.8.

5. The rhodium-doped strontium titanate particles according to claim 1 , wherein the absorbance at a wavelength of 1800 nm is greater than or equal to 0.5 to less than or equal to 0.7.

6. The rhodium-doped strontium titanate particles according to claim 1 , the rhodium-doped strontium titanate particles having an R sp value of not less than 0.86.

7. Photocatalysts for splitting water comprising the rhodium-doped strontium titanate particles according to claim 1 .

8. A process for producing the rhodium-doped strontium titanate particles having a primary particle diameter of not more than 70 nm and having an absorbance at a wavelength of 570 nm of not less than 0.6 and an absorbance at a wavelength of 1800 nm of not more than 0.7, each absorbance being determined by measuring a diffuse reflection spectrum, comprising:
providing a solution of a titanium compound, a rhodium compound, a strontium compound, and a hydrophobic complexing agent dissolved in water; and drying the solution to obtain a residue and firing the residue.

9. The process for producing the rhodium-doped strontium titanate particles according to claim 8 , wherein the solution further comprises water dispersible organic polymer particles.

10. The process for producing the rhodium-doped strontium titanate particles according to claim 8 , wherein the firing is carried out at a temperature of higher than 800° C. to lower than 1100° C.

11. A method for splitting water, comprising irradiating the rhodium-doped strontium titanate particles according to claim 1 with visible light, the rhodium-doped strontium titanate particles being in contact with water.

Assignees

• Toto Ltd

Inventors

• Tokudome Hiromasa
• Okunaka Sayuri

Classifications

• Y02E60/36

  Hydrogen production from non-carbon containing sources, e.g. by water electrolysis · CPC title

• B01J35/45

  Nanoparticles · CPC title

• B01J37/0211

  using a colloidal suspension · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• C01P2004/04

  obtained by TEM, STEM, STM or AFM · CPC title