JP7429442B2 - Hydrogen detection element, hydrogen sensor, light control member, and light control window - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydrogen sensing element, a hydrogen sensor, a light control member, and a light control window to which a material exhibiting gaschromic reaction is applied.

Materials that exhibit chromic reactions, a phenomenon in which optical properties change reversibly in response to external stimuli, are widely known. Chromic reactions are mainly divided into electrochromic reactions and gaschromic reactions. Electrochromic reactions involve redox reactions due to the application of voltage. In gas chromic reactions, reduction and oxidation occur by gas molecules in the atmosphere.

Hydrogen sensors are one of the uses of materials that exhibit chromic reactions (hereinafter referred to as "chromic materials").

In factories manufacturing glass, steel, chemicals, fuel cells, semiconductors, etc., hydrogen gas may be used or generated during the manufacturing process of semiconductors, etc.
The explosive range of hydrogen gas is wide, ranging from 4% by volume to 75% by volume. Additionally, hydrogen gas is tasteless, odorless, and light, making it difficult to handle. Furthermore, fuel cells and fuel cell vehicles that use hydrogen gas as fuel also have the risk of explosion due to hydrogen gas. Therefore, it is necessary to handle hydrogen gas with care and to monitor and detect hydrogen gas leaks.
Known methods for detecting hydrogen gas include a catalytic combustion method, a gas heat conduction method, and a semiconductor method. Existing methods such as catalytic combustion are employed in commercially available hydrogen gas sensors. However, existing methods require heating and combustion to increase detection sensitivity, which poses a safety problem. Furthermore, existing methods consume a large amount of energy during standby. Furthermore, existing methods do not have sufficient reliability because the hydrogen detection element deteriorates quickly and its characteristics tend to become unstable.
By using a chromic reaction, hydrogen gas can be detected at room temperature (see Patent Documents 1 to 4).

Patent Document 1 states, ``A solid electrolyte that is flat and has proton conductivity, a catalyst electrode provided on one main surface of the solid electrolyte to dissociate hydrogen gas molecules into protons and electrons, and a catalyst electrode that A reference electrode provided on the other main surface of the solid electrolyte to recombine the generated protons and electrons on the other main surface of the solid electrolyte, and electron conductivity for sending electrons generated at the catalyst electrode to the reference electrode. 1. A hydrogen sensor that detects hydrogen gas by measuring a potential difference between a catalyst electrode and a reference electrode.

Patent Document 2 discloses a selective thin film gas sensor consisting of a tungsten oxide thin film formed on a substrate such as silicon oxide or ceramics, in which the tungsten oxide thin film is formed in an atmosphere with a low oxygen concentration (1 to 10%). It is described that it is deposited by a reactive radio frequency sputtering method using a metallic tungsten target and has a composition of WO _3-δ (δ<0.2) (claims 1 and 6).

Patent Document 3 discloses a hydrogen gas detection member that includes a cerium oxide-containing layer, a tungsten oxide-containing layer, and a catalytic metal element-containing layer, and whose light absorption characteristics change according to changes in hydrogen gas concentration ( Claim 1) states that the cerium oxide-containing layer, the tungsten oxide-containing layer, and the catalytic metal element-containing layer are formed by depositing on a substrate by sputtering (paragraphs [0118] to [0118]). 0121])

Patent Document 4 describes that a hydrogen storage body including a hydrogen storage layer and a catalyst layer that exhibits a chromic reaction is used for a hydrogen sensing element and a hydrogen sensor (claims 1, 7, and 8). Further, it is described that a protective layer is provided on the side of the catalyst layer opposite to the hydrogen storage layer (claim 5).

Further, the chromic material can be used as a light control member such as a light control window by controlling the atmospheric gas.
Generally, in buildings, windows are the places where a large proportion of light and heat enter and exit. For example, during heating in the winter, the proportion of light and heat flowing out from windows is about 50% of the total heat flowing out of the building, and during cooling in the summer, the proportion of light and heat flowing through the windows is approximately 50%. This accounts for about 70% of the total heat generated. Therefore, by appropriately controlling the inflow and outflow of light and heat through windows, enormous energy savings can be achieved.

Electrochromic dimming windows in which a tungsten oxide (WO ₃ ) thin film is formed on a glass substrate have almost reached the stage of practical use, and commercial products are also available. In addition, gaschromic light control windows do not require counter electrodes or voltage application means, and can be dimmed simply by switching the gas in the atmosphere in contact with the light control member, so compared to electrochromic light control glass, It has a simple structure and can be manufactured at low cost. Therefore, many studies have been made on the material of the light control member and the structure of the light control window (see Non-Patent Document 1 and Patent Documents 4 to 6).

Non-Patent Document 1 describes a gaschromic light control element in which a layer of a mixture in which nanopalladium particles are attached to the surface of nickel oxyhydroxide particles is formed on a transparent substrate (Abstract).

Patent Document 4 also describes that a hydrogen storage body including a hydrogen storage layer and a catalyst layer that exhibits a chromic reaction is used in a gas chromic light control element (claim 6).

Patent Document 5 discloses a light control device having a tungsten oxide layer having chromic characteristics formed on a substrate and a catalyst layer, the catalyst layer including a silicon dioxide thin film and palladium particles dispersed in the silicon dioxide thin film. An element is disclosed (Claim 1, paragraph [0001]).

Patent Document 6 describes a light control element equipped with a light control layer containing a Prussian blue metal complex having gaschromic properties and catalyst nanoparticles that promote a redox reaction of the metal complex. Item 1).

Japanese Patent Application Publication No. 2007-278876 Special Publication No. 63-51501 International Publication No. 2016/143385 International Publication No. 2018/055946 Japanese Patent Application Publication No. 2015-161860 Patent No. 6703686

Chih-Wei Hu; Yasusei Yamada; Kazuki Yoshimura, “Fabrication of nickel oxyhydroxide/palladium (NiOOH/Pd)nanocomposite for gasochromic application”, SolarEnergy Materials and Solar Cells, 2016, Issue 23, p.5390-5397

However, in Patent Document 1, in order to detect hydrogen gas using electrochromic characteristics, an electrometer or the like is required, and the structure of the hydrogen sensor becomes complicated.

Further, in the hydrogen gas sensor manufacturing methods described in Patent Documents 2 and 3, depending on the sputtering conditions, it is possible to obtain an amorphous phase WO ₃ film exhibiting chromic characteristics or a CeO ₂ composite WO ₃ film. However, the films using metal oxides described in Patent Documents 2 and 3 are known to have weak weather resistance. In addition, in order to exhibit good characteristics as a hydrogen gas sensor, it is necessary to use a large amount of a noble metal catalyst such as platinum on the surface of the hydrogen detection element (WO ₃ film).
The light control elements described in Non-Patent Document 1 and Patent Document 5 also have problems with weather resistance, as in Patent Documents 2 and 3, because the metal oxide is used as the hydrogen detection layer.

Patent Documents 4 and 6 describe a Prussian blue type complex as a gaschromic material having hydrogen detection ability. However, when this material is used in an environment where moisture is present, it easily dissolves in water, so there is a problem that it does not have sufficient weather resistance. Patent Document 4 describes that a protective layer having hydrogen permeability and water impermeability is provided on the opposite side of the catalyst layer from the hydrogen storage layer (Claim 5, paragraphs [0047] and [0048 ]). However, since hydrogen gas has high permeability through the aqueous phase, it is difficult to achieve both water impermeability and hydrogen permeability, and there is a risk that hydrogen detection may not be performed accurately.
Patent Document 6 describes that organic solvent dispersibility may be improved by adsorbing a compound having both an amino group and an alkyl group on the surface of the Prussian blue metal complex particles constituting the light control layer. (paragraph [0058]). However, such surface treatment inhibits the permeation of hydrogen gas into the light control layer, so there is a risk that quick and sufficient light control may not be achieved.

An object of the present invention is to provide a hydrogen sensing element that is weather resistant and capable of quickly and accurately detecting hydrogen even in an environment containing a lot of water and steam.
Another object of the present invention is to provide a hydrogen sensor that can quickly and accurately detect hydrogen using the above-mentioned hydrogen sensing element.
Furthermore, an object of the present invention is to provide a highly sensitive light control member using the above-mentioned hydrogen detection element, and a light control window equipped with the light control member.

The present invention adopts the following means in order to solve the above problems.
[1] A hydrogen sensing element comprising a hydrogen sensing layer having gaschromic properties including a metal cyano complex and catalyst nanoparticles,
The metal cyano complex and the catalyst nanoparticles are hydrophobized, and
The hydrogen sensing layer is a hydrogen sensing element in which the contact angle with water droplets on the surface in contact with gas is 15.0° or more and 75.0° or less.

[2] The hydrogen sensing element according to [1], wherein the metal cyano complex and the catalyst nanoparticle are modified with a compound having an amino group and an alkyl group.

[3] The metal cyano complex has a reduction potential of -0.38 [VvsAg/AgNO ₃ ] or more and an oxidation potential of +0.46 [VvsAg/AgNO ₃ ] or less, [1] or [2] hydrogen detection element.

[4] The metal cyano complex has a reduction potential of -0.38 [VvsAg/AgNO ₃ ] or more, and an oxidation potential of +0.46 [VvsAg/AgNO ₃ ] or more and +2.14 [VvsAg/AgNO ₃ ] or less. The hydrogen sensing element according to [1] or [2] above.

[5] The hydrogen sensing element according to any one of [1] to [4], wherein the catalyst nanoparticles include one or more selected from the group consisting of palladium, palladium alloy, platinum, and platinum alloy.

[6] The hydrogen sensing element according to any one of [1] to [5] above, wherein the catalyst nanoparticles have an average particle size of 1 nm or more and 100 nm or less.

[7] The hydrogen sensing element according to any one of [1] to [6], wherein the hydrogen sensing layer has a thickness of 10 nm or more and 2 μm or less.
[8] The hydrogen sensing element according to any one of [1] to [7], wherein the hydrogen sensing layer is formed by dispersing the catalyst nanoparticles in the metal cyano complex.

[9] The hydrogen detection layer according to any one of [1] to [7], wherein the hydrogen detection layer is formed by laminating a layer containing the catalyst nanoparticles on the layer containing the metal cyano complex. element.

[10] A hydrogen sensor using the hydrogen sensing element according to any one of [1] to [9] above, wherein the hydrogen sensing layer is formed on a base material.

[11] The hydrogen sensor according to [10] above, wherein the base material is a glass base material, a metal base material, a ceramic base material, or a plastic base material.

[12] A light control member using the hydrogen sensing element according to any one of [1] to [9] above, wherein the hydrogen sensing layer is formed on a transparent base material.

[13] The light control member of [12] above;
another transparent base material disposed opposite to the hydrogen sensing layer side of the light control member;
By supplying and exhausting the atmosphere in the gap between the light control member and the other transparent base material by switching between hydrogen or a gas containing hydrogen and oxygen, ozone, or an oxidizing gas containing one or more of oxygen and ozone. atmosphere control means for controlling;
with dimming windows.

According to one aspect of the present invention, it is possible to provide a hydrogen sensing element that has weather resistance and can quickly and accurately detect hydrogen even in an environment containing a lot of water and steam.
Further, according to another aspect of the present invention, it is possible to provide a hydrogen sensor that can quickly and accurately detect hydrogen using the above-described hydrogen sensing element.
Furthermore, according to other aspects of the present invention, it is possible to provide a highly sensitive light control member using the above hydrogen sensing element and a light control window equipped with the light control member.

A diagram showing an example of the hydrogen sensing layer according to the present embodiment (catalyst nanoparticles are dispersed in a metal cyano complex) A diagram showing another example of the hydrogen sensing layer according to the present embodiment (a catalyst nanoparticle layer is stacked on a metal cyano complex layer) A diagram showing an example of a hydrogen sensing element according to the present embodiment A diagram showing an example of a light control window according to the present embodiment FT-IR spectrum of hydrogen sensing element according to Example 1 Schematic diagram showing an optical device for measuring light transmittance of a hydrogen sensing element according to Example 1 Light transmission spectrum of hydrogen sensing element according to Example 1 A diagram showing the relationship between a change in the atmosphere (hydrogen or ozone) of the gas-filled space of the hydrogen sensing element according to Example 1 and a change in light transmittance. A diagram showing the relationship between a change in the atmosphere (hydrogen or air) of the gas-filled space of the hydrogen sensing element according to Example 1 and a change in light transmittance. Cyclic voltammogram of the hydrogen sensing element according to Example 1 Contact angle of hydrogen sensing elements according to Examples 1 to 8 and Comparative Examples 1 and 2 A diagram showing the relationship between changes in the atmosphere of the gas-filled space and changes in light transmittance of the hydrogen sensing elements according to Examples 1 to 8. A diagram showing the relationship between the change in the atmosphere of the gas-filled space and the change in light transmittance of the hydrogen sensing elements according to Comparative Examples 1 and 2. A diagram showing the relationship between the change in the atmosphere of the gas-filled space and the change in light transmittance of the hydrogen sensing elements according to Example 9 and Comparative Example 3. Light transmission spectrum of hydrogen sensing element according to Example 9 FT-IR spectra of hydrogen sensing elements according to Examples 1, 3, 6 to 8 FT-IR spectra of gas-filled spaces of hydrogen sensing elements according to Example 9 and Comparative Examples 1 to 3

Next, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be explained, but various modifications and substitutions may be made to the following embodiment without departing from the scope of the present invention. I can do it. Furthermore, in this specification, when a numerical range is expressed using "~", the numbers at both ends of "~" are included, unless otherwise specified.

[Hydrogen detection element]
The hydrogen sensing element according to the present embodiment includes a hydrophobized metal cyano complex (hereinafter also referred to as a "hydrophobized metal cyano type complex") and a hydrophobized catalyst nanoparticle (hereinafter also referred to as a "hydrophobized catalyst nanoparticle"). ) has a hydrogen sensing layer with gas chromic properties.
In addition, in this specification, "hydrophobicization" refers to making the "metal cyano complex" and the "catalyst nanoparticles" dispersible in organic solvents instead of dispersible in water.

For example, as shown in FIG. 1, the hydrogen sensing layer 10 according to the present embodiment can have a structure in which a hydrophobized metal cyano complex 10a and a hydrophobization catalyst nanoparticle 10b are mixed. The hydrogen sensing layer 10 reversibly changes its light transmittance through an oxidation-reduction reaction with the atmospheric gas, that is, it reversibly changes between a colorless (transparent) state and a colored state. Since the hydrogen detection layer is made of a hydrophobic material, it can exhibit high hydrogen detection performance even in areas with a lot of moisture without being subject to oxidation or decomposition. The catalyst nanoparticles 10b function as a catalyst for the redox reaction of the metal cyano complex 10a. In this case, as shown in FIG. 1, a portion of the catalyst nanoparticles 10b may be exposed on the surface of the hydrogen sensing layer.

FIG. 2 shows another example of the hydrogen sensing layer 10 according to this embodiment. It is also possible to have a laminate structure in which a catalyst nanoparticle layer 20b containing catalyst nanoparticles is attached to the surface of the metal cyano complex layer 20a.

FIG. 3 shows an example of a hydrogen sensing element 130 according to this embodiment, in which the hydrogen sensing layer 10 shown in FIG. 1 is laminated on a base material 120. In this case, the thickness of the hydrogen sensing layer 10 is preferably 10 nm or more and 2 μm or less, more preferably 50 nm or more and 1 μm or less. When the thickness of the hydrogen sensing layer 10 is 10 nm or more and 2 μm or less, the change in color of the hydrogen sensing layer 10 becomes easier to visually recognize.

A hydrogen sensing element may be formed using a hydrogen sensing layer 20 in which a metal cyano complex layer 20a and a catalyst nanoparticle layer 20b shown in FIG. 2 are laminated. In this case, the thickness of the metal cyano complex layer 20a is preferably 10 nm or more and 1.9 μm or less, more preferably 50 nm or more and 1 μm or less. The thickness of the catalyst nanoparticle layer 20b is preferably 2 nm or more and 100 nm or less, more preferably 2 nm or more and 50 nm or less.

[Method for manufacturing hydrogen sensing element]
The hydrogen sensing element according to this embodiment can be produced by preparing a dispersion containing the metal cyano complex 10a and the catalyst nanoparticles 10b, and forming the hydrogen sensing layer 10 on the base material 120 by a wet coating method. can. The solvent used for preparing the dispersion is not particularly limited as long as it is an organic solvent, and examples thereof include hexane, benzene, diethyl ether, ethanol, butanol, chloroform, ethyl acetate, toluene, and non-polar organic solvents. Among them, toluene is preferred.

Wet coating methods include, but are not particularly limited to, spin coating methods, spray coating methods, dip coating methods, drop coating methods, roll-to-roll methods, and the like. By employing the wet coating method, the hydrogen sensing layer 10 with a large surface area can be formed at high speed. Further, since an expensive vacuum device or the like is not used, the hydrogen sensing element 130 can be manufactured at a much lower cost than when conventional inorganic materials or metals are used.

The hydrogen sensing element may be produced by separately preparing a dispersion containing a metal cyano complex and a dispersion containing catalyst nanoparticles, and sequentially wet-coating them onto a substrate. The solvent used for preparing the dispersion is not particularly limited, and the same solvents as mentioned above can be mentioned, and among them, toluene is preferable.

[Base material]
The material constituting the base material 120 is not particularly limited. Examples include glass substrates, metal substrates, ceramic substrates, plastic substrates, and the like. Examples of glass substrates include quartz, sapphire, and oxides such as lithium niobate. A transparent substrate such as a plastic substrate may be used instead of the glass substrate.

The metal base material is not particularly limited, and examples thereof include metals such as aluminum, tantalum, nickel, copper, titanium, niobium, and iron, and alloys such as stainless steel and duralumin. The ceramic base material is not particularly limited, and may be, for example, a dielectric ceramic material, a ferrite material, a semiconductor ceramic material, or a piezoelectric ceramic material. For example, BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , CaZrO ₃ , SrFeO ₃ , Ni-Zn ferrite, Mn-Zn ferrite, Ni-Zn-Cu ferrite, Mn-Zn-Cu ferrite, Mn-Zn-Ni Examples include ferrite-based ceramics, spinel-based ceramics, lead zirconate titanate-based ceramics, and the like. Depending on the characteristics of the desired product, the ceramic base material is made of the above-mentioned ceramic material as a main component, and may contain sub-components such as Mn compounds, Mg compounds, Si compounds, Fe compounds, Cr compounds, Co compounds, Ni compounds, and rare earth compounds. It may further contain components. Materials constituting the plastic base material include, but are not particularly limited to, polyethylene terephthalate (PET), acrylic resin, and the like. Cellophane tape or the like may be used as the plastic base material. The shape of the base material is not particularly limited, but examples include a plate shape, a sheet shape, and the like.

[Gaschromic properties]
The gas chromic properties according to this embodiment may be colorless (transparent) when in an oxidized state, and colored when in a reduced state. Further, it may be colorless when in a reduced state and colored when in an oxidized state. In this embodiment, the metal cyano complex has a light transmittance that changes in the wavelength range of 400 to 870 nm, and can change between a colorless (transparent) state and a colored state, so for example, the metal cyano complex transmits light with a wavelength of 700 nm. By measuring the ratio, a colorless (transparent) state and a colored state can be evaluated.

The atmospheric gas that causes the metal cyano complex to change color can be a gas containing hydrogen, oxygen, ozone, or the like. As the atmospheric gas, a combination of at least two gases, ie, a gas that promotes the reduction of the metal cyano complex and a gas that promotes the oxidation of the metal cyano complex, can be used. For example, a gas containing hydrogen as the reducing gas and a gas containing oxygen as the oxidizing gas can be used in combination. Furthermore, a combination of a gas containing hydrogen as the reducing gas and a gas containing ozone as the oxidizing gas can be used. As the oxidizing gas, a gas containing oxygen and ozone can be used, and air can also be used.

Specifically, when Prussian blue is used as the metal cyano complex of the hydrogen sensing layer 10, when the oxidizing gas is switched to a hydrogen-containing gas, the color changes from blue to colorless. In addition, it has the same composition as Prussian blue as a metal cyano complex, and when a complex containing nickel and iron is used, it changes from yellow to colorless, and when a complex containing copper and iron is used, it changes from brown to colorless. Changes to

In the present embodiment, it is preferable that the reduction potential of the metal cyano complex 10a is −0.38 [VvsAg/AgNO ₃ ] or higher, and the oxidation potential of the metal cyano complex 10a is +2.14 [VvsAg/AgNO ₃ ] or lower. Thereby, it is possible to have gas chromic characteristics with respect to a specific atmospheric gas, which will be described later. Furthermore, when the oxidation potential is below +0.46 [VvsAg/AgNO ₃ ], a gas with lower oxidizing power can be used as the oxidizing gas of the atmospheric gas, as described later. Note that the potential [VvsAg/AgNO ₃ ] is a standard potential measured with reference to a silver-silver nitrate electrode for organic solvents.
The electrochemical properties of a metal cyano complex can be determined by measuring the reduction peak potential and oxidation peak potential of a given metal cyano complex by cyclic voltammetry (CV).

When the hydrogen sensing layer 10 equipped with a metal cyano complex having a reduction potential of -0.38 [VvsAg/AgNO ₃ ] or more is exposed to an atmosphere containing hydrogen, catalyst nanoparticles present in the hydrogen sensing layer 10 are removed. 10b (FIG. 1) or the catalyst nanoparticle layer 20b (FIG. 2) laminated on the metal cyano complex layer 20a, the metal cyano complex 10a or the metal cyano complex layer 20a is reduced, and the wavelength changes. The light transmittance changes in the range of 400 to 870 nm, and the color of the metal cyano complex 10a or the metal cyano complex layer 20a changes.

At this time, the following reaction occurs due to the hydrogen-containing atmosphere and the hydrogen sensing layer 10. That is, the metal cyano complex 10a or the metal cyano complex layer 20a reacts with hydrogen as shown in the following formula (1) by the catalytic action of the catalyst nanoparticles 10b or the catalyst nanoparticle layer 20b attached therein or on the surface. do.

H ₂ → 2H ⁺ +2e ^- (E=-0.38 [VvsAg/AgNO ₃ ])...(1)
Here, E is the redox potential. It can be said that the atmosphere containing hydrogen has a reducing ability of -0.38 [VvsAg/AgNO ₃ ]. Therefore, if the reduction potential of the metal cyano complex is -0.38 [VvsAg/AgNO ₃ ] or higher, it can react well with hydrogen. Therefore, by using a gas containing hydrogen as the reducing gas, it is possible to cause the hydrogen sensing element 10 to change color.

On the other hand, when the hydrogen sensing layer 10 is exposed to an atmosphere containing oxygen such as air, the following reaction (2) occurs between oxygen and the hydrogen sensing element layer 10.
O ₂ +2H ₂ O+4e ⁻ →4OH ⁻ (E=+0.46 [VvsAg/AgNO ₃ ])…(2)
That is, it can be said that oxygen has an oxidizing ability of +0.46 [VvsAg/AgCl]. Therefore, if the oxidation potential of the metal cyano complex is +0.46 [VvsAg/AgCl] or less, it can react favorably with oxygen. Therefore, by using a gas containing oxygen as the oxidizing gas, it is possible to cause the hydrogen sensing layer 10 to change color.

Further, when the hydrogen sensing layer 10 is exposed to an atmosphere containing ozone, a reaction expressed by the following formula (3) occurs between ozone and the hydrogen sensing layer 10.
O ₃ +2H ⁺ +2e ^- =O ₂ +H ₂ O (E=+2.14[VvsAg/AgNO ₃ ])...(3)
That is, it can be said that ozone has a stronger oxidizing ability than oxygen, which is +2.14 [VvsAg/AgNO ₃ ]. Therefore, even if the oxidation potential of the metal cyano complex is +0.46 [VvsAg/AgNO ₃ ] or more, as long as it is +2.14 [VvsAg/AgNO3] or less, it can react favorably with ozone. Therefore, by using a gas containing ozone as the oxidizing gas, it is possible to cause the hydrogen sensing layer 10 to change color.

[Metal cyano complex]
The metal cyano complex according to the present embodiment is a crystal in which a cyano group (CN) bridges a metal atom ^MA and a metal atom ^MB . As used herein, metal cyano complexes include Prussian blue and analogues having a similar structure to Prussian blue.

The basic compositional formula of the metal cyano complex used is:
A _x M ^A [ ^MB (CN) ₆ ] _y・zH ₂ O…(4)
It is acceptable as long as it is expressed as . In formula (4), A is a cation, and M ^A and M ^B are each metal atoms. In the above formula, a part of the cyano group (CN) may be substituted with a hydroxyl group, an amino group, a nitro group, a nitroso group, water, or the like.

In formula (4), the metal atom M ^A is vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lanthanum, europium, gadolinium, lutetium, barium, strontium, and calcium. The metal atom ^MA is preferably iron, cobalt, nickel, vanadium, copper, manganese, or zinc, and more preferably iron, copper, or nickel. When using a combination of two metals for the metal atom ^MA , a combination of iron and nickel, a combination of iron and copper, or a combination of nickel and copper is preferable, and a combination of iron and nickel is more preferable. preferable.

In formula (4), the metal atom ^M is one or more metal atoms selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper. . Among them, iron, chromium, or cobalt is preferable as the metal atom ^MB , and iron is particularly preferable. Regarding the metal atom M ^B , a combination of iron and chromium, a combination of iron and cobalt, or a combination of chromium and cobalt is preferred, and a combination of iron and chromium is more preferred.

In formula (4), the cation A does not necessarily need to be contained, and when it is contained, examples include, but are not limited to, potassium, sodium, cesium, rubidium, hydrogen, and ammonia. Further, it may contain other materials such as anions. Moreover, it is not necessary to necessarily contain water (H ₂ O). Further, as long as half or more of the complex maintains the structure represented by this compositional formula, it may be mixed with another complex or the like. For example, metal ions, organic molecules, other metal complexes, etc. may be adsorbed to improve optical response, catalytic activity, dispersibility, adsorption to substrates, etc. Even in such cases, color It suffices if the main structure of the changing portion has the above compositional formula.

In formula (4), x is a number from 0 to 3, preferably a number from 0 to 1. y is a number from 0.3 to 1.5, preferably from 0.5 to 1. z is a number from 0 to 30, preferably from 5 to 15.

As mentioned above, a metal cyano complex is a crystal formed by a cyano group (CN) bridged between a metal atom M ^A and a metal atom M ^B , but around this crystal there are cations of the metal atom M ^C And/or a metal cyano complex anion having a metal atom ^MD as a central metal bound thereto may be arranged. The metal atom M ^C is from the group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lanthanum, europium, gadolinium, lutetium, barium, strontium, and calcium. It may be one or more selected metal atoms. Further, the metal atom ^MD may be one or more metal atoms selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper.

[Hydrophobization of metal cyano complex]
This embodiment is characterized in that the metal cyano complex is made hydrophobic, that is, its dispersibility in organic solvents is improved. As a means for this, it is preferable to adsorb modification molecules for improving hydrophobicity onto the surface of the metal cyano complex particles. From this point of view, it is preferable to coexist a compound having an amino group in the metal cyano complex. The compound having an amino group may be in an ionic state.

When dispersing the metal cyano complex using an alcohol such as toluene, benzene or butanol, in order to improve the organic solvent dispersibility, an amino group and an alkyl group (preferably 3 to 100 carbon atoms, more preferably 3 to 100 carbon atoms) are used to disperse the metal cyano complex. 30, more preferably 3 to 18 carbon atoms), and it is even more preferable to combine the above amine compound with a ferrocyanide ion or a ferricyanide ion. Specifically, the amine compound is preferably oleylamine, stearylamine, propylamine, hexylamine, etc., with oleylamine, hexylamine, and propylamine being particularly preferable. When combined with ferrocyanide ion or ferricyanide ion, oleylamine and propylamine are particularly preferred. The concentration of the amine compound is preferably from 0.5 equivalent (mol) to 3 equivalent relative to the metal cyano complex.

The concentration of the hydrophobized metal cyano complex particles in the dispersion is not particularly limited, but in consideration of good coating and film-forming properties, it is necessary to adjust the concentration to an appropriate concentration by a coating method. For example, when coating is performed by a spin coating method, the content is preferably 1% by mass or more and 50% by mass or less, and when a spray method is used, the content is preferably 0.1% by mass or more and 15% by mass or less.

The particle size of the hydrophobized metal cyano complex is preferably an average particle size of 500 nm or less, more preferably an average particle size of 200 nm or less, in order to be uniformly dispersed in the solvent. Although there is no particular lower limit to the average particle size, it is practical for the average particle size to be 3 nm or more due to the manufacturing method. Note that the average particle size in this specification is the average particle size of a particle size distribution determined by a dynamic light scattering method (photon correlation method).

[Catalyst nanoparticles]
The material constituting the catalyst nanoparticles is not particularly limited as long as it functions as a catalyst for the redox reaction of the metal cyano complex used, but palladium, palladium alloys, platinum, platinum alloys, etc. may be used, and two or more types may be used in combination. You can.

By making the catalyst nanoparticles nanosized, the surface area per unit volume increases, so that the catalytic ability can be improved compared to, for example, micron-order particles. The average particle size of the catalyst nanoparticles is preferably 1 nm or more and 100 nm or less, more preferably 1 nm or more and 30 nm or less.

[Hydrophobization of catalyst nanoparticles]
It is preferable that the hydrophobization catalyst nanoparticles according to this embodiment have a protective layer formed on the surface of the particles using a compound having an amino group or a thiol group. The protective layer is provided in order to improve dispersibility in organic solvents, avoid the influence of water, and suppress increase in the particle size of catalyst particles.

The compound having an amino group or a thiol group is not particularly limited, but for example, the following general formula (5)
R ¹ -NH ₂ (5)
[In the formula, R ¹ is a monovalent group having 2 to 20 carbon atoms and represents a saturated hydrocarbon group or an unsaturated hydrocarbon group. ]
Examples of the amine group include dodecylamine represented by the following formula (6).

The hydrophobization catalyst nanoparticles are prepared, for example, in a reaction tank at room temperature by a toluene organic solution of a metal compound containing platinum as a main component, a toluene solution of dodecylamine constituting the protective layer, and a sodium borohydride reducing agent (NaBH). ₄ ), hydrophobized catalyst nanoparticles containing platinum can be synthesized.
The concentration of the amine compound forming the protective layer is preferably 10 to 30 times the molar amount of the catalyst nanoparticles.

[Water wettability increasing treatment]
In this embodiment, a process is performed to increase the water wettability of the surface of the hydrogen sensing layer that comes into contact with gas so that hydrogen gas can quickly permeate into the hydrogen sensing layer. Preferably, a UV ozone cleaner device is used for this treatment. Ultraviolet rays with a wavelength of 184.9 nm emitted from the UV ozone cleaner device decomposes carbon-carbon bonds in organic matter and decomposes oxygen molecules to generate oxygen atoms, which are oxygen molecules in the air O ₂ Combines with O3 to produce ozone _O3 . The simultaneously irradiated ultraviolet light with a wavelength of 253.7 nm decomposes ozone to generate active oxygen O ^{2 -} , and the active oxygen combines with decomposed carbon of organic matter to become a volatile gas, which can remove hydrophobic groups. Therefore, by controlling the UV irradiation by the UV ozone cleaner device, it is possible to control the decrease in hydrophobic groups (increase in water wettability) on the surface of the hydrogen sensing layer. Further, the water wettability of the surface of the hydrogen sensing layer can be evaluated by measuring the contact angle θ between the surface and water droplets.
By increasing the water wettability of the surface of the hydrogen sensing layer, hydrogen gas penetration occurs quickly and the gas chromic effect is improved.

Note that the water wettability increasing treatment can also be performed by heat treatment, vacuum plasma treatment, atmospheric pressure plasma treatment, etc. For example, the temperature in the case of heat treatment is preferably 50°C or more and 150°C or less, more preferably 70°C or more and 145°C or less, and more preferably 90°C or more and 135°C or less.

In this embodiment, the contact angle θ is measured by a droplet method using model ECA-1 manufactured by Kyowa Interface Science Co., Ltd. Specifically, when water droplets are brought into contact with the surface of the hydrogen sensing layer 10 that has been dried in advance in a drying oven (temperature: 95 degrees Celsius, 30 minutes). is analyzed to calculate the angle between the water droplet and the surface of the hydrogen sensing layer 10. The contact angle θ described in this specification is measured at three locations on the same surface and represents the average value of the three values. The contact angle θ is preferably 15.0° or more and 75.0° or less, more preferably 20.0° or more and 60.0° or less, and 25.0° or more and 45.0° or less. It is more preferable.

[Hydrogen sensor]
The hydrogen sensing element 130 according to this embodiment can employ the configuration of the hydrogen sensing element 130 shown in FIG. 3 as is, and can be used as a hydrogen sensor. Unlike electronic hydrogen detection sensors, this hydrogen sensor does not require external electrical equipment or electrical current. Therefore, compared to electronic hydrogen detection sensors, there is a greater degree of structural freedom. Note that this embodiment is not limited to the configuration shown in FIG. 3 as long as the gas that induces redox reaches the catalyst appropriately and the catalyst and the metal cyano complex are placed close to each other to some extent. For example, there may be a structure in which a metal cyano complex is supported on a nonwoven fabric, and catalyst nanoparticles are further supported therein. Further, in the example of FIG. 3, the shape of the base material 120 is a flat plate, but the base material may have another shape, for example, a spherical shape.

[Dimmer component]
The hydrogen sensing element 130 according to this embodiment can be used as a light control member when the hydrogen sensing layer 10 is formed on the base material 120 such as transparent glass.
The light control member can be used as a light control window 70 illustrated in FIG. 4. The light control window 70 is arranged to face the hydrogen sensing element (hereinafter also referred to as "light control member") 130 and the hydrogen detection layer (hereinafter also referred to as "light control layer") 10 side. A gas filling chamber S is provided, which is formed by another transparent base material 60 and a seal member 40 that seals an opening between the transparent base materials.

The gas filling chamber S is filled with argon gas in advance, and the atmosphere controller 50 can switch between hydrogen, oxygen, or air to supply and exhaust the gas. For example, the atmosphere controller 50 can electrolyze water to supply hydrogen or oxygen to the gas-filled chamber S, and can exhaust hydrogen or oxygen from the gas-filled chamber S using a vacuum pump.

When hydrogen or a gas containing hydrogen is supplied to the gas filling chamber S, the light control layer 10 is reduced and its color changes. Further, when oxygen or a gas containing oxygen such as air is supplied to the gas filling chamber S, the light control layer 10 is oxidized and returns to its original state.

Therefore, by controlling the atmosphere of the gas filling chamber S using the atmosphere controller 50, the light control layer 10 can reversibly control the light transmittance between the reduced state and the oxidized state. Further, by interrupting the air supply and exhaust by the atmosphere controller 50, the reduced state or the oxidized state can be maintained. Thereby, a light control window 70 capable of controlling light using a gaschromic method is obtained.

Currently, it is becoming mainstream to use double-glazed glass in newly built houses, so by equipping the inside of the double-glazed glass with a light control layer using a metal cyano complex, the interior space can be filled with gas for switching. It can be used as room S.

EXAMPLES The present invention will be described in more detail below based on Examples, but the present invention is not to be construed as being limited thereto.

<Preparation 1: Synthesis of hydrophobized metal cyano complex particles>
To an aqueous solution in which 14.5 g of sodium ferrocyanide decahydrate was dissolved in 60 mL of water, 30 mL of an aqueous solution in which 16.2 g of iron nitrate nonahydrate was dissolved in water was mixed and stirred for 5 minutes. The blue precipitate that separated out was centrifuged, washed three times with water, then once with methanol, and dried under reduced pressure. The yield was 11.0 g, and the yield was 97.4% as Fe ₄ [Fe(CN) ₆ ] _{3.15H 2} O.
5.0 g of the obtained metal cyano complex aggregate was suspended in 10 mL of water and 75 mL of toluene. When 4.0 mL of oleylamine was added to this suspension and stirred for one week, the suspension changed to a deep blue transparent solution or dispersion. Thereafter, 10.0 g of sodium sulfate was added, stirred for three days to remove water, centrifuged to separate the upper layer liquid and lower layer precipitate, and from the upper layer a toluene dispersion of hydrophobized metal cyano complex particles (A1 ) was obtained.

<Preparation 2: Synthesis of hydrophobized catalyst nanoparticles>
After mixing 104 mg of platinum (IV) chloride (H ₂ PtCl ₆ ), 10 mL of water, 330 mg of tetra(decyl)ammonium bromide (C ₄ 0H ₈₄ BrN), and 30 mL of toluene with stirring, the mixture was reacted at room temperature for 2 hours. , the platinum component was transferred from the aqueous phase to the organic phase. Furthermore, when 690 mg of dodecylamine (C ₁₂ H ₂₇ N) was added and stirred, the solution became white. 125 mg of sodium borohydride (NaBH ₄ ) was added as a reducing agent and stirred to obtain a toluene dispersion of nanoplatinum particles. At this time, the solution before the reaction had a pale yellow color, but once the hydrophobized nanoplatinum particles were generated, the solution changed to a dark brown color. The reduction reaction formula is as follows.
2Pt ⁴⁺ + BH ₄ ^- + 4H ₂ O → 2Pt + B(OH) ₄ ^- +8H ⁺ (2)

The resulting dispersion was mixed with 400 mL of water using a separating funnel, and the toluene in the upper layer was collected. Upper layer toluene and 400 mL of ethanol were mixed and stored in a -18°C freezer for 24 hours, thereby obtaining a precipitate of hydrophobized nanoplatinum particles. The hydrophobized nanoplatinum particles were dispersed in toluene to obtain a 0.5 wt % dispersion (B1). The average particle size of the nanoplatinum particles was measured by a dynamic light scattering method using a particle size distribution analyzer (Photol ELSZ-1000, manufactured by Otsuka Electronics Co., Ltd.) and found to be 2.6 nm.

<Preparation 3: Preparation of mixed solution of hydrophobized metal cyano complex particles and hydrophobized catalyst nanoparticles>
6.0 mL of the hydrophobized metal cyano complex particle dispersion (A1) prepared in Preparation Example 1 and 3.0 mL of the hydrophobized catalyst nanoplatinum particle dispersion (B1) of Preparation Example 2 were stirred for 2 hours to form a mixed solution. (C1) was obtained.

(Example 1)
<Preparation procedure 1: Spin coating film formation of a mixed solution of hydrophobized metal cyano complex and hydrophobized catalyst nanoplatinum particles>
A glass substrate 120 with a length of 3.0 cm, a width of 3.0 cm, and a thickness of 1.1 mm was placed in a spin coater, and 0.15 mL of the mixed solution (C1) obtained in Preparation 3 was added dropwise, and the mixture was rotated at 500 rpm for 10 minutes. Spin coating was performed for 10 seconds, followed by rotation at 750 rpm for 10 seconds. This was left standing in the atmosphere at about 25° C. for 30 minutes to form a hydrogen sensing layer 10 containing hydrophobized metal cyano complex particles 10a and hydrophobized catalyst nanoplatinum particles 10b on the base material 120. Note that the thickness of the hydrogen sensing layer 10 formed on the substrate was about 300 nm.

<Production procedure 2: Treatment to increase water wettability>
The substrate on which the hydrogen sensing layer 10 was formed was placed in a UV ozone cleaner (UV253V16 manufactured by Filgen) so that the hydrogen sensing layer faced 5 cm from an ultraviolet lamp, and after introducing oxygen for 3 minutes, UV irradiation with two wavelengths of .9 nm and 253.7 nm was performed simultaneously for 60 minutes to produce the hydrogen sensing element 130 according to Example 1.

<FT-IR spectrum of hydrogen sensing element>
The hydrogen sensing layer 10 of the hydrogen sensing element 130 according to Example 1 became a uniform blue film in the air. The FT-IR spectrum of the hydrogen sensing layer 10 was measured using Frontier (trademark) manufactured by PerkinElmer Japan as an FT-IR Fourier transform near-infrared/mid-infrared/far-infrared spectrometer.
As shown in FIG. 5, the FT-IR spectrum of the hydrogen sensing layer 10 in the hydrogen sensing element 130 according to Example 1 includes an absorption peak (2088 cm ^-1 ) due to the cyano group of the metal cyano complex and an alkyl group of oleylamine. Absorption peaks (2855 and 2925 cm ⁻¹ ) attributed to were observed.

<Contact angle θ of hydrogen sensing layer with water droplets>
The contact angle θ of the hydrogen sensing layer 10 of the hydrogen sensing element 130 according to Example 1 with a water droplet was measured using a contact angle measuring device under the above-mentioned conditions, and was found to be 51.7°.

<Measurement of optical properties of hydrogen sensing element>
The optical characteristics of the hydrogen sensing element 130 according to Example 1 were measured using a silica glass substrate as the base material 120 and an optical apparatus shown in FIG.
The optical device has a configuration similar to the light control window 70 shown in FIG.
Hydrogen was supplied to the atmosphere controller 50 using a model OPGU-7200 manufactured by HORIBA at a flow rate of 100% hydrogen: 60 SCCM.
Air or ozone was supplied using SoecV350 manufactured by Marco Corporation, and air was supplied at an air flow rate of 5 L/min, and ozone was supplied at an ozone output of 200 mg/h and an air flow of 5 L/min. .
As the spectrometer 90, USB4000 (manufactured by Ocean Optics) was used.

FIG. 7 shows a light transmission spectrum of the hydrogen sensing element according to Example 1. In FIG. 7, the light transmission spectra in the oxidized state and the reduced state are shown in Table 1. Air and an atmosphere containing 100% hydrogen (hereinafter referred to as hydrogen atmosphere) are placed in a gas-filled chamber S at room temperature under the above conditions. Measurements were taken at room temperature after supplying air for 5 minutes.

From FIG. 7, the hydrogen sensing element according to Example 1 shows a large change in transmittance of light with a wavelength of 700 nm in the oxidized state and the reduced state (transmittance change of 55.2%), and is a high-performance gas chromic device. It can be seen that it has the following characteristics.

Next, after supplying a hydrogen atmosphere to the gas filling chamber S under the above conditions for 120 seconds, the supply of hydrogen atmosphere is stopped for 30 seconds, and ozone is supplied under the above conditions, making this one cycle. The air supply control of the hydrogen atmosphere was repeated five times, and the transmittance of light with a wavelength of 700 nm was measured every second during that time.

FIG. 8 shows the relationship between the change in the atmosphere of the gas filling chamber S and the change in the light transmittance at 700 nm. From FIG. 8, it can be seen that in the first hydrogen atmosphere supply control, the transmittance of light with a wavelength of 700 nm changes from 30.0% to 97.4% due to the hydrogen supply. In addition, in the second to fourth hydrogen atmosphere air supply controls, by stopping the hydrogen supply and letting ozone flow in, the transmittance of light with a wavelength of 700 nm changed from 97.3% to 26.2%. I know that. From FIG. 8, it can be seen that the hydrogen detection element according to Example 1 can repeatedly change color by switching the supply of hydrogen and ozone, so that the hydrogen detection ability is reversibly restored by ozone treatment.

Next, after a hydrogen atmosphere was supplied to the gas filling chamber S under the above conditions for 120 seconds, the supply of hydrogen atmosphere was stopped, and air was supplied under the above conditions. From FIG. 9, the transmittance of the hydrogen sensing element according to Example 1 at a wavelength of 700 nm changed from 84.2% to 45.0% by introducing air, and then became transparent when hydrogen was introduced again. I understand. Therefore, it can be seen that even when ozone is not used, it can be repeatedly used as a hydrogen sensor or a light control member.

<Electrochemical properties of hydrogen sensing element>
In order to measure the electrochemical properties of the hydrogen sensing element according to Example 1, 150 μL of the mixed solution (C1) of the hydrophobized metal cyano complex particles and the hydrophobized catalyst nanoplatinum particles obtained in Preparation Example 3 was placed in a 3 cm x 3 cm area. This was spin-coated onto a glass substrate with a conductive ITO film, and UV irradiation was performed for 60 minutes to obtain a working electrode on which a hydrogen sensing layer was laminated.

For this working electrode, 0.1 M potassium bis(trifluoromethanesulfonyl)imide (K ⁺ TFSI ⁻ ) was used as the electrolyte in a tripolar cell with an Ag/AgNO ₃ electrode as a reference electrode and a platinum wire as a counter electrode. , cyclic voltammetry (CV) was performed in acetonitrile solution.

FIG. 10 shows a cyclic voltammogram of the hydrogen sensing element according to Example 1 described above (sweep rate: 10 mV/s). In FIG. 10, the waveform is a surface adsorption wave, suggesting that the hydrogen sensing layer does not dissolve in the acetonitrile solution and exists stably. It is also seen that the oxidation peak potential exists at least around +0.05V [VvsAg/AgNO ₃ ] and -0.16V [VvsAg/AgNO ₃ ]. On the other hand, the reduction peak potential exists at least at -0.05 [VvsAg/AgNO ₃ ] and -0.36 [VvsAg/AgNO ₃ ]. Therefore, the metal cyano complex used in the hydrogen sensing element according to Example 1 has at least two redox pairs, has a reduction potential of -0.38 [VvsAg/AgNO ₃ ] or higher, and has an oxidation potential of +0.38 [VvsAg/AgNO 3 ] or higher. 46 [VvsAg/AgNO ₃ ] or less.

(Example 2 to Example 8, Comparative Examples 1 and 2)
Nine spin-coated films on the substrates obtained by production procedure 1 were prepared, and each was subjected to UV irradiation treatment for the following time to detect hydrogen detection according to Examples 2 to 8 and Comparative Examples 1 and 2. A hydrogen sensing element with layers was fabricated. Example 2: 20 minutes, Example 3: 30 minutes, Example 4: 45 minutes, Example 5: 75 minutes, Example 6: 90 minutes, Example 7: 100 minutes, Example 8: 120 minutes, Comparison Example 1: 0 minutes, comparative example 120 minutes.

FIG. 11 shows the contact angle θ with water droplets on the surface of the hydrogen sensing layer in Example 1 (UV irradiation treatment for 60 minutes), Examples 2 to 8, and Comparative Examples 1 and 2. From FIG. 11, it can be seen that the contact angles θ of Example 1 and Examples 2 to 8 are all 15.0° or more and 75.0° or less. On the other hand, the contact angles θ of Comparative Examples 1 and 2 are 84.9° and 5.2°, respectively.

For Examples 2 to 8, Comparative Example 1, and Comparative Example 2, the light transmission characteristics were measured in the same manner using the same optical device as in Example 1.

FIG. 12 shows the relationship between the transmittance of light at a wavelength of 700 nm of the hydrogen sensing elements according to Example 1 and Examples 2 to 8 and changes in the atmosphere of the gas-filled chamber S. FIG. 13 shows the above relationship between the hydrogen sensing elements according to Comparative Examples 1 and 2. The light transmittance was first measured in air, and after about 25 seconds, a hydrogen atmosphere was supplied to the gas filling chamber S for 275 seconds (Examples 1 to 8) or 325 seconds (Comparative Examples 1 to 2). Light transmittance was measured every 0.1 seconds during this period. In the hydrogen sensing elements according to Example 1 and Examples 2 to 8, the transmittance of light with a wavelength of 700 nm changes significantly in a short period of time. Although a change in transmittance was observed, in Comparative Examples 1 and 2, almost no change in transmittance was observed.

Table 1 shows the gaschromic characteristics of the hydrogen sensing elements according to Examples 1 to 8 and Comparative Examples 1 and 2. The transmittance in the oxidation state (air state) and the reduction state (after hydrogen introduction) are the values when the gas filling chamber S is in the air state, and the values 275 seconds after switching to the supply air in the hydrogen atmosphere (Example 1). -8) or after 325 seconds (Comparative Examples 1 and 2) measured at room temperature.

From Table 1, the hydrogen sensing elements according to Examples 1 to 8 have appropriate surface water wettability with a contact angle θ with water droplets on the surface of the hydrogen sensing layer between 70.4° and 27.5°, It can be seen that the change in transmittance of light with a wavelength of 700 nm in the oxidized state and the reduced state exceeds 46%, indicating that it has excellent gas chromic properties that allow visual confirmation of color change.
On the other hand, in the hydrogen sensing element according to Comparative Example 1, which was not exposed to UV irradiation and had a large contact angle θ of 84.9°, the change in transmittance of light at 700 nm was as small as 9.7%. In the hydrogen sensing element according to Comparative Example 2, in which UV irradiation was performed for 200 minutes and the contact angle θ was as small as 5.2°, the change in transmittance of light at 700 nm was 2.0%. Therefore, in both Comparative Examples 1 and 2, it was difficult to visually observe the color change in the oxidized state and the reduced state.

(Example 9, Comparative Example 3)
The spin-coated film formed on the substrate according to Production Procedure 1 was heat-treated in a drying oven (DX402 manufactured by YAMATO) at 130° C. for 24 hours to produce a hydrogen sensing element according to Example 9. The contact angle of the hydrogen sensing layer with the water droplets was 58.9°.
Further, a hydrogen sensing element according to Comparative Example 3 was produced in the same manner as in Example 9 except that the heat treatment time was changed to 30 minutes. The contact angle of the hydrogen sensing layer with the water droplets was 78.4°.

FIG. 14 shows that the transmittance of light at a wavelength of 700 nm in the air of the hydrogen sensing elements according to Example 9 and Comparative Example 3 was measured using the optical apparatus shown in FIG. This is a graph obtained by supplying a hydrogen atmosphere to the gas filling chamber S for 600 seconds after 60 seconds and measuring the change in light transmittance over time. The hydrogen sensing element according to Example 9 has a transmittance of 24.4% for light with a wavelength of 700 nm in air, and a transmittance of 62.5% after introducing hydrogen gas for 600 seconds, and the change in transmittance is as follows. It was 38.1%. On the other hand, the hydrogen sensing element according to Comparative Example 3 has a transmittance of 28.3% at 700 nm in air and a transmittance of 50.3% after introducing hydrogen gas for 600 seconds. Therefore, the transmittance changed by only 22.0%.

Moreover, FIG. 15 shows the light transmission spectrum of the hydrogen sensing element according to Example 9 in an air condition and after introducing hydrogen gas for 1500 seconds (25 minutes). Since the change in transmittance at a wavelength of 650 nm after hydrogen introduction was as large as 41.9%, it can be seen that the hydrogen sensing element according to Example 9 is suitable for applications where it is desirable for the transmittance to change slowly.

<FT-IR spectrum>
FIG. 16 shows the FT-IR spectra of Examples 1, 3, and 6 to 8. In FT-IR spectrum measurement, an absorption peak range due to cyano groups (2150-2000 cm ^-1 ) and an absorption peak range due to alkyl functional groups (3000-2800 cm ^-1 ) were observed, indicating that the metal cyano complex The presence of a cyano group and a hydrophobic alkyl functional group of the amino compound can be seen.
The hydrophobic alkyl functional groups present on the surface of the hydrogen sensing layer impede contact between hydrogen gas and the hydrogen sensing layer, preventing hydrogen gas from penetrating and reacting quickly with the hydrogen sensing layer.
In Example 3, the UV irradiation time was 30 minutes, which was shorter than in Example 1, and the peaks of cyano groups and alkyl functional groups were high. As shown in FIG. 12, the transmittance due to hydrogen penetration changes over about 300 seconds (5 minutes), so the color change occurs more slowly than in Example 1, but since the metal cyano complex structure is less destroyed, the transmittance changes. The changes are big.
In Examples 6 to 8, where the UV irradiation time was 90 to 120 minutes, which was longer than Example 1, the peak of the alkyl functional group that impeded the penetration of hydrogen gas almost disappeared, and as shown in Figure 12, the transmittance change was 25 minutes. Completed within seconds. Therefore, it is suitable for applications where it is desirable for the transmittance to change more quickly.

FIG. 17 shows FT-IR spectra of the hydrogen sensing elements according to Comparative Examples 1 to 3 and Example 9. In the hydrogen sensing element according to Comparative Example 1, which was not exposed to UV irradiation, the peak due to the alkyl functional group was high, so the hydrophobicity of the surface was maintained, making it difficult for hydrogen gas to come into contact with the hydrogen sensing layer, as shown in FIG. 13. As such, the gaschromic effect is difficult to demonstrate. In addition, in the hydrogen sensing element according to Comparative Example 2 in which the UV irradiation treatment time was excessive, the peak of the alkyl functional group disappeared, but the height of the peak due to the cyano group was also greatly reduced, so it had gaschromic characteristics. It is thought that the metal cyano complex structure was destroyed and the gas chromic properties disappeared.
Although the hydrogen sensing element according to Comparative Example 3 whose heat treatment time was 30 minutes had a reduced number of alkyl functional groups compared to Comparative Example 1, it was not sufficient to have sufficient surface water wettability, so as shown in FIG. It is thought that the gas chromic reaction rate was slow and the performance was low.
On the other hand, in the hydrogen sensing element according to Example 9 in which the heat treatment time was 24 hours, the alkyl functional groups on the surface of the hydrogen sensing layer were further reduced than in Comparative Example 3, and a certain amount of cyano groups remained. 3. Hydrogen gas permeates more easily. Therefore, a sufficient chromic reaction can be carried out, which is slower than in Examples 1 to 8 but faster than in Comparative Example 3.

As described above in detail, the hydrogen sensing element according to the present invention includes a hydrogen sensing layer containing a hydrophobized metal cyano complex and a hydrophobized catalyst nanoparticle, and the hydrogen sensing element has a water wettability on the surface of the hydrogen sensing layer. Because of its increased hydrogen content, it has weather resistance even in environments with a lot of water and steam, and can quickly and accurately detect hydrogen using its gas chromic properties.
Further, the hydrogen sensing element according to the present invention can be manufactured at low cost because only a small amount of expensive catalyst nanoparticles is needed. Furthermore, the hydrogen sensing element according to the present invention can be manufactured by a simple process and has a simple structure.
Therefore, the present invention can be used in hydrogen sensing elements, hydrogen sensors, light control members, light control windows, etc. that have excellent gaschromic properties and are inexpensive.

10a Metal cyano complex 10b Catalyst nanoparticles 10 Hydrogen sensing layer (light control layer)
20a Metal cyano complex layer 20b Catalyst nanoparticle layer 120 Base material 130 Hydrogen sensing element (light control member)
40 Seal member 50 Atmosphere controller 60 Transparent base material 70 Light control window 80 Light source 90 Spectrophotometer S Gas filling chamber

Claims (13)

A hydrogen sensing element comprising a hydrogen sensing layer having gaschromic properties including a metal cyano complex and catalyst nanoparticles,
The metal cyano complex and the catalyst nanoparticles are hydrophobized, and
The hydrogen sensing layer is a hydrogen sensing element in which the contact angle with water droplets on the surface in contact with gas is 15.0° or more and 75.0° or less. The hydrogen sensing element according to claim 1, wherein the metal cyano complex and the catalyst nanoparticle are modified with a compound having an amino group and an alkyl group. The hydrogen sensing element according to claim 1 or 2, wherein the metal cyano complex has a reduction potential of -0.38 [VvsAg/AgNO ₃ ] or more and an oxidation potential of +0.46 [VvsAg/AgNO ₃ ] or less. . The metal cyano complex has a reduction potential of -0.38 [VvsAg/AgNO ₃ ] or more, and an oxidation potential of +0.46 [VvsAg/AgNO ₃ ] or more and +2.14 [VvsAg/AgNO ₃ ] or less. The hydrogen sensing element according to claim 1 or 2. The hydrogen sensing element according to any one of claims 1 to 4, wherein the catalyst nanoparticles include one or more selected from the group consisting of palladium, palladium alloy, platinum, and platinum alloy. The hydrogen sensing element according to any one of claims 1 to 5, wherein the catalyst nanoparticles have an average particle size of 1 nm or more and 100 nm or less. The hydrogen sensing element according to any one of claims 1 to 6, wherein the hydrogen sensing layer has a film thickness of 10 nm or more and 2 μm or less. The hydrogen sensing element according to any one of claims 1 to 7, wherein the hydrogen sensing layer is formed by dispersing the catalyst nanoparticles in the metal cyano complex. 8. The hydrogen sensing element according to claim 1, wherein the hydrogen sensing layer is formed by laminating a layer containing the catalyst nanoparticles on the layer containing the metal cyano complex. A hydrogen sensor using the hydrogen sensing element according to any one of claims 1 to 9, wherein the hydrogen sensing layer is formed on a base material. The hydrogen sensor according to claim 10, wherein the substrate is a glass substrate, a metal substrate, a ceramic substrate, or a plastic substrate. A light control member using the hydrogen sensing element according to any one of claims 1 to 9, wherein the hydrogen sensing layer is formed on a transparent base material. A light control member according to claim 12;
another transparent base material disposed opposite to the hydrogen sensing layer side of the light control member;
By supplying and exhausting the atmosphere in the gap between the light control member and the other transparent base material by switching between hydrogen or a gas containing hydrogen and oxygen, ozone, or an oxidizing gas containing one or more of oxygen and ozone. atmosphere control means for controlling;
with dimming windows.