Photocatalyst dispersion element, method for producing photocatalyst dispersion element, photocatalyst body, and method for producing photocatalyst body

1. A photocatalyst dispersion element comprising:

a photocatalytic material;

a solvent; and

an ion additive,

the ion additive generating a cation having a smaller ion radius than a tetramethylammonium ion in the solvent,

wherein hydrogen ion exponent is set to pH 7.5 or less by containing the ion additive,

wherein a content of the ion additive is 1.5×10 −3 mol or less.

2. The element according to claim 1 , wherein the ion additive generates at least one selected from the group consisting of an alkali metal ion, an alkaline earth metal ion, and an ammonium ion.

3. The element according to claim 1 , wherein the ion additive includes at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, and ammonium hydroxide.

4. The element according to claim 1 , wherein a content of the photocatalytic material is 20 wt % or less.

5. The element according to claim 1 , wherein the photocatalytic material is tungsten oxide.

6. The element according to claim 1 , further comprising:

a coupling agent configured to couple particles of the photocatalytic material when the solvent is dried.

7. The element according to claim 6 , wherein a content of the coupling agent is one tenth or more of a content of the photocatalytic material.

8. The element according to claim 6 , wherein a particle diameter of the coupling agent is comparable to or smaller than a particle diameter of the photocatalytic material.

9. The element according to claim 1 , wherein the solvent is evaporated at room temperature.

10. A method for producing a photocatalyst dispersion element, comprising:

adjusting hydrogen ion exponent of a solvent so as to fall in a range of suppressing decrease of catalytic activity of a photocatalyst to be formed; and

mixing a photocatalytic material in the solvent,

wherein the hydrogen ion exponent of the solvent is adjusted so as to fall in a range of pH 7.5 or less,

wherein the hydrogen ion exponent of the solvent is adjusted by using an ion additive generating a cation having a smaller ion radius than a tetramethylammonium ion in the solvent, and a content of the ion additive is set to 1.5×10 −3 mol or less.

11. The method according to claim 10 , wherein the photocatalytic material is tungsten oxide.

12. A photocatalyst body comprising:

a substrate; and

a photocatalyst formed by adhering a photocatalyst dispersion element to a surface of the substrate and drying the photocatalyst dispersion element,

the photocatalyst dispersion element including:

a photocatalytic material;

a solvent; and

an ion additive,

the ion additive generating a cation having a smaller ion radius than a tetramethylammonium ion in the solvent,

wherein hydrogen ion exponent is set to pH 7.5 or less by containing the ion additive,

wherein a content of the ion additive is 1.5×10 −3 mol or less.

13. The body according to claim 12 , wherein the photocatalyst contains a metal oxide and includes a coupling between a metallic element and a hydroxy group.

14. The body according to claim 12 , wherein the photocatalyst has an absorption peak in a range of 3500-3800 cm−1 in Fourier transform infrared spectroscopic measurement.

15. The body according to claim 12 , wherein the photocatalyst contains tungsten oxide.

16. A method for producing a photocatalyst body, comprising:

adhering a photocatalyst dispersion element to a surface of a substrate,

the photocatalyst dispersion element including:

a photocatalytic material;

a solvent; and

an ion additive,

the ion additive generating a cation having a smaller ion radius than a tetramethylammonium ion in the solvent,

wherein hydrogen ion exponent is set to pH 7.5 or less by containing the ion additive,

wherein a content of the ion additive is 1.5×10 −3 mol or less.