JP6331439B2 - Electrode, hydrogen generator, and method for generating hydrogen - Google Patents

Description

  The present invention relates to an electrode, a hydrogen generator, and a method for generating hydrogen.

  Conventionally, it has been proposed to use apatite containing titanium ions such as titanium apatite as a photocatalyst.

Titanium apatite (TiCa ₉ (PO ₄ ) ₆ (OH) ₂ ) has a high adsorption power. Therefore, unlike titania (TiO ₂ ), which is another photocatalyst, titanium apatite adsorbs organic substances in the atmosphere or water without using an adsorption auxiliary material that assists adsorption, and the adsorbed organic substances are absorbed by ultraviolet light. Photolysis can be achieved by irradiation. The organic matter decomposed by the titanium apatite eventually becomes water and carbon dioxide. At this time, heat equivalent to the difference between the free energy of the organic substance and the decomposed product is generated in addition to the energy that the irradiated light brings into the reaction system.

  The above-described photocatalyst such as titania can decompose water into oxygen and hydrogen by irradiating with ultraviolet light by using a hydrogen generating catalyst such as platinum supported on a photocatalyst powder.

  As a method for decomposing water using a photocatalyst, there is a method called a photoelectrochemical cell method in addition to the method using the above powder. In this method, using a first electrode having a thin-film photocatalyst and a second electrode formed of a metal having a hydrogen-producing catalytic function such as platinum, the photocatalyst is irradiated with light to generate oxygen from the first electrode. Then, hydrogen is generated from the second electrode. In some cases, a slight bias voltage is applied to the electrode. In this method, charge separation of electron-hole pairs generated by light irradiation is performed by band bending generated in the surface region of the thin-film photocatalyst, and the electrons move to the second electrode to reduce water and reduce hydrogen. The holes generated and left in the first electrode oxidize water to generate oxygen.

  As can be seen from the operation principle of the photoelectrochemical cell method described above, the energy level at the lower end of the conduction band of the photocatalyst is lower than the reduction potential of water in order to reduce the water by the photocatalyst to generate hydrogen. First of all, it is required. Although the energy level at the lower end of the conduction band of titanium apatite has been unknown so far, the present inventors have recently confirmed that the energy level at the lower end of the conduction band of titanium apatite is sufficiently lower than the reduction potential of water. It has been revealed that.

JP 2000-136112 A JP 2000-327315 A

Toshihisa Anazawa et al., Proceedings of the 73rd Japan Society of Applied Physics, 13p-C13-20, (2012)

  Thus, it has been studied to produce hydrogen by reducing water by a photoelectrochemical cell method using thin-film titanium apatite as a photocatalyst having a high adsorbing power.

  However, the electrode having a thin film of titanium apatite has problems such as high electrical resistance and low mechanical strength.

  Therefore, an object of the present specification is to propose an electrode that solves the above-described problem.

  Another object of the present specification is to propose a hydrogen generator that solves the above-described problems.

  Furthermore, this specification makes it a subject to propose the method of producing | generating hydrogen which solves the problem mentioned above.

  According to one embodiment of the electrode disclosed in the present specification, a photocatalyst formed by a catalyst underlayer formed of an ion-bonding conductor and apatite containing titanium ions as metal ions and laminated on the catalyst underlayer. And a layer. However, here, the ion-bonding conductor means a conductor having a bias of electric charge and formed of a metal element and other elements, or a non-metal element and other elements.

  Further, according to one embodiment of the hydrogen generator disclosed in this specification, the catalyst underlayer formed of an ion-bonding conductor and an apatite containing titanium ions as metal ions are formed on the catalyst underlayer. A first electrode having a stacked photocatalyst layer; and a second electrode electrically connected to the first electrode and having a hydrogen generation catalyst function.

  Furthermore, according to one embodiment of the method for generating hydrogen disclosed in the present specification, the catalyst underlayer is formed of a catalyst underlayer formed of an ion-bonded conductor and apatite containing titanium ions as metal ions. Using a first electrode having a photocatalyst layer stacked thereon, an organic substance in an aqueous solution is oxidized and electrically connected to the first electrode, and a second electrode having a hydrogen generation catalyst function is used. Reduce water to produce hydrogen.

  According to one embodiment of the electrode disclosed in this specification, hydrogen can be generated.

  As described above, according to one embodiment of the hydrogen generator disclosed in this specification, hydrogen can be generated.

  Furthermore, according to one embodiment of the method for generating hydrogen disclosed in the present specification, hydrogen can be generated.

  The objects and advantages of the invention will be realized and obtained by means of the elements and combinations particularly pointed out in the appended claims.

  Both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed.

1 is a diagram illustrating a first embodiment of a hydrogen generator disclosed in this specification. FIG. It is a figure explaining reaction of an electrode. It is a figure which shows the relationship between the production | generation of hydrogen and the thickness of a photocatalyst layer. It is a figure which shows the mass spectrometry result of product gas. It is a figure which shows 2nd Embodiment of the hydrogen generator disclosed in this specification. It is a figure explaining reaction of an electrode.

  The inventors of the present application studied generating hydrogen by using an electrode having an apatite containing titanium ions as metal ions as a layered photocatalyst. Specifically, the electrode having the photocatalyst is irradiated with light to oxidize organic substances in the aqueous solution and reduce water to generate hydrogen.

  The reason why it is difficult to use apatite containing titanium ions as metal ions (hereinafter also simply referred to as Ti apatite) as a layer and stacked on a substrate for use as an electrode will be described below. Here, it is preferable that Ti apatite has an apatite type crystal structure, the metal ion contained in this apatite type crystal structure is an alkaline earth metal, and contains titanium ions as metal ions.

  First, in Ti apatite, the substitution sites of titanium ions have a non-uniform distribution in the crystal, and there are also vacancy sites. Due to these effects, distortion occurs in the crystal lattice. Have many carrier trap sites. Therefore, Ti apatite has low conductivity even if it has a crystal structure. Therefore, the electron-hole pair generated by the light irradiation is recombined before moving to the electrode, and thus it is difficult to take out from the electrode.

  Further, Ti apatite formed in a layer form has low mechanical strength because it has low adhesion to a substrate formed of a metal such as Pt. In addition, there is a problem that the energy barrier that hinders the carrier from moving between the photocatalytic layer of Ti apatite and the substrate is high, and the interface resistance is high.

  Accordingly, the inventors of the present application have come up with the idea of using an electrode formed by laminating a Ti apatite photocatalyst layer on a catalyst underlayer formed of an ion-bonding conductor.

  The crystal of Ti apatite has a polyhedral structure, and has a positively charged surface and a negatively charged surface even though it is not charged as a whole. When a photocatalyst layer formed of such Ti apatite crystal particles is laminated on a catalyst underlayer formed of an ion-bonding conductor, the photocatalyst layer and the catalyst underlayer are separated by an ion-bonded electrostatic force. It is thought to combine. Specifically, the positively charged surface of the Ti apatite crystal particles is bonded to the negative ions of the catalyst underlayer by electrostatic attraction, and the negatively charged surface of the Ti apatite crystal is the catalyst underlayer. It couple | bonds by electrostatic attraction between these positive ions.

  Using the first electrode formed by laminating the photocatalyst layer formed of Ti apatite on the catalyst underlayer and the second electrode having a hydrogen generation catalyst function, hydrogen is generated by irradiating light. A hydrogen generator can be formed.

  Hereinafter, based on the above-described idea, a preferred first embodiment of the hydrogen generator disclosed in this specification will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the invention described in the claims and equivalents thereof.

  FIG. 1 is a diagram illustrating a first embodiment of a hydrogen generator disclosed in this specification.

  The hydrogen generator 10 of this embodiment includes a substrate 13, a catalyst base layer 11a stacked on the substrate 13, a first electrode 11 having a photocatalyst layer 11b stacked on the catalyst base layer 11a, and a first electrode. 11 and a second electrode 12 electrically connected.

  The catalyst base layer 11a is formed of an ion-bonding conductor. The photocatalyst layer 11b is formed of apatite containing titanium ions as metal ions. The second electrode 12 has a hydrogen generation catalyst function.

  The substrate 13 has a horizontally long shape, and the catalyst base layer 11a is formed on both sides of the substrate 13 over the entire length direction. The photocatalyst layer 11b is formed so as to be laminated on the catalyst base layer 11a from one end portion of the substrate 13 to a middle portion toward the other end portion in the longitudinal direction of the substrate 13. The photocatalyst layer 11b is not laminated at the other end portion side in the longitudinal direction of the substrate 13, and the catalyst base layer 11a is exposed.

  The wire-like second electrode 12 is wound on the catalyst base layer 11a on the other end side in the longitudinal direction of the substrate 13, and is electrically connected to the catalyst base layer 11a. The second electrode 12 may be electrically connected to the photocatalytic layer 11b.

  The second electrode 12 is at least electrically connected to the catalyst base layer 11a of the first electrode 11, and promotes the movement of electrons generated in the photocatalyst layer 11b to the second electrode 12 by light irradiation. From the viewpoint of

  The catalyst base layer 11a may have ionic bonding properties and may have covalent bonding properties or metal bonding properties.

  As a material for forming the catalyst underlayer 11a, for example, an oxide semiconductor, transition metal carbide or nitride, or the like can be used. In this specification, the ion-bonding conductor includes a conductor having a conductivity similar to that of a semiconductor.

  Specifically, fluorine-added tin oxide (FTO), tin-added indium oxide (ITO), or zinc oxide (ZnO) can be used as a material for forming the catalyst base layer 11a. Further, as a material for forming the catalyst underlayer 11a, a carbide or nitride of a Group 4, Group 5, or Group 6 transition metal such as TiC can be used.

  The catalyst underlayer 11a may be formed by forming a film on the substrate 13 and baking using a sputtering method or a sol-gel method. Further, the catalyst base layer 11a may be formed by applying a paste-like material on the substrate 13 and baking it.

  The catalyst underlayer 11a preferably has a thickness of at least about 1 μm in order to suppress an increase in electrical resistance and ensure mechanical strength.

  The upper limit of the thickness of the catalyst base layer 11a is not particularly limited, but when the catalyst base layer 11a is formed using a light transmitting material and light is irradiated to the photocatalyst layer 11b through the catalyst base layer 11a. From the viewpoint of light transmittance, the upper limit of the thickness of the catalyst base layer 11a can be determined.

  The photocatalyst layer 11b is formed in a layer shape using apatite (Ti apatite) containing titanium ions as metal ions. In Ti apatite, for example, a part of calcium in the apatite crystal structure is replaced with titanium of titanium oxide having a photocatalytic action, and the replacement of calcium with titanium is performed by ion exchange based on a coprecipitation method. Can be obtained. Here, it is preferable that Ti apatite does not include the crystal structure of titanium oxide, and that titanium of titanium oxide and calcium of apatite are incorporated at an atomic level. In Ti apatite, it is preferable that all or part of calcium ions in the apatite crystal structure is substituted with titanium ions. Here, apatite means that apatite other than calcium apatite is included. Ti apatite can be formed using, for example, the method disclosed in Patent Document 1.

As a material for forming Ti apatite, titanium calcium phosphate hydroxyapatite (TiCa ₉ (PO ₄ ) ₆ (OH) ₂ or titanium strontium phosphate hydroxyapatite (TiSr ₉ (PO ₄ ) ₆ (OH) ₂ can be used. These Ti apatites have a catalytic action when irradiated with ultraviolet light.

Further, titanium calcium vanadate hydroxyapatite (TiCa ₉ (VO ₄ ) ₆ (OH) ₂ can be used as a material for forming Ti apatite. Titanium calcium vanadate hydroxyapatite (TiCa ₉ (VO ₄ ) ₆ (OH) ₂ has a catalytic action when irradiated with light having a wavelength in the visible light region as well as ultraviolet light, and therefore, when a light source having a broad spectrum such as sunlight is used, titanium is used. By using calcium vanadate hydroxyapatite (TiCa ₉ (VO ₄ ) ₆ (OH) ₂ , light energy can be used efficiently.

Furthermore, as a material for forming Ti apatite, silver titanium calcium hydroxyapatite (TiAg _x Ca _y (PO ₄ ) ₆ (OH) ₂ (where x + y˜ 9) The silver titanium calcium hydroxyapatite has a catalytic action when irradiated with light having a wavelength in the visible light region wider than that of the titanium calcium vanadate hydroxyapatite described above. Can be used efficiently.

  The Ti apatite described above has a hydroxyl group, but the Ti apatite may not have a hydroxyl group. For example, the hydroxyl group may be substituted with fluorine.

  The second electrode 12 has a hydrogen generation catalyst function in which electrons move from the first electrode 11 to reduce water and generate hydrogen. By applying an overvoltage to the second electrode 12, an energy barrier that hinders electrons from moving to water can be reduced, and the hydrogen generation rate can be improved. Forming the second electrode 12 using a material having a low overvoltage is preferable for improving the hydrogen generation rate.

  As a material for forming the second electrode 12, for example, platinum group metals such as Pt, Ir, Ru, Pd, and Rh, Au, and the like, and alloys or compounds thereof can be used. Further, as a material for forming the second electrode 12, an alloy or compound of Fe, Ni, Se constituting the active center of hydrogenase that is a hydrogen-producing enzyme, a combination thereof, or the like can be used.

  FIG. 2 is a diagram for explaining the reaction of the electrodes.

The first electrode 11 and the second electrode 12 shown in FIG. 1 are immersed in a methanol (CH ₃ OH) aqueous solution, and the first electrode 11 and the second electrode 12 are irradiated with light having a wavelength that develops a photocatalytic function to the photocatalyst layer 11b. A reaction example on the surfaces of the first electrode 11 and the second electrode 12 will be described below.

In the first electrode 11, there is CH ₃ OH (a) adsorbed on the surface of the photocatalyst layer 11b. In the photocatalyst layer 11b was irradiated with photoelectrons e- · holes h + pairs are generated, holes h + are bound to _CH 3 OH _(a), and CH 3 OH (a) is oxidized, _CH 3 O ( a) and H + (a) are generated on the surface of the photocatalytic layer 11b.

When oxygen (O ₂ ) is dissolved in an aqueous methanol solution, a part of CH ₃ O (a) finally becomes water and carbon dioxide gas through several photochemical or thermal processes.

In the first electrode 11, among the generated electron e ⁻ .hole h ⁺ pairs, the hole h ⁺ is consumed to oxidize methanol, so that recombination of the electron e ⁻ with the hole h ⁺ is suppressed. . Then, the electrons e ⁻ move from the first electrode 11 to the second electrode 12.

On the other hand, on the surface of the second electrode 12, there is H ⁺ (a) on which H ⁺ generated on the surface of the first electrode 11a is adsorbed. This H ⁺ (a) is in equilibrium with H ₃ O ⁺ combined with H ₂ O.

Electrons e ⁻ generated in the photocatalytic layer 11b move to the second electrode 12 and combine with H ⁺ (a) to generate H (a). H (a) combines with other H (a) to generate H ₂ . In this way, the second electrode 12 generates hydrogen by reducing water.

  As described above, from the viewpoint of efficiently producing hydrogen by oxidizing organic substances such as methanol and reducing water, the photocatalyst layer 11b has a small thickness. It is preferable to move to.

  Since Ti apatite is a material with poor carrier mobility, as described above, even if the Ti apatite is laminated on the catalyst underlayer 11a, the thin photocatalyst layer 11b prevents carrier recombination. Preferred above.

  As will be described in detail below, the present inventors have investigated the relationship between the generation of hydrogen and the thickness of the photocatalyst layer 11b, and as a result, have found that the thickness of the photocatalyst layer 11b is preferably 2 μm or less. Although there is no restriction | limiting in particular about the lower limit of the thickness of the photocatalyst layer 11b, Actually, it will be about 50-100 nm which is the diameter of the primary particle of Ti apatite.

  FIG. 3 is a diagram showing the relationship between hydrogen generation and the thickness of the photocatalyst layer.

  The hydrogen generator shown in FIG. 1 was formed, and the relationship between hydrogen generation and the thickness of the photocatalyst layer was examined.

  The hydrogen generator 10 having the photocatalyst layer 11b having a thickness of 1 μm to 10 μm was formed as follows.

A glass substrate was used as the substrate 13. Fluorine-added tin oxide (FTO) was used as a material for forming the catalyst underlayer 11a. Titanium calcium phosphate hydroxyapatite (TiCa ₉ (PO ₄ ) ₆ (OH) ₂ was used as a material for forming the photocatalyst layer 11b.

  First, a catalyst underlayer 11a having a thickness of 1 μm was formed on the substrate 13.

Next, titanium calcium phosphate hydroxyapatite (TiCa ₉ (PO ₄ ) ₆ (OH) ₂ pulverized with a ball mill was dispersed in ethanol to prepare a suspension.

  Next, the catalyst base layer 11a is partially immersed in the suspension, and titanium calcium phosphate hydroxyapatite is deposited on the catalyst base layer 11a by using an electrophoresis method. Layer 11b was formed. The thickness of the photocatalyst layer 11b was 1 μm.

  Next, a wire is wound on the portion of the catalyst base layer 11a that has not been immersed in the suspension so that the platinum wire and the catalyst base layer 11a are electrically connected to form the second electrode 12. Thus, a hydrogen generator 10 was obtained.

  In the hydrogen generator 10 having the photocatalyst layer 11b having a thickness of 50 μm and 70 μm, the photocatalyst layer 11b was formed using a squeegee method. Specifically, first, a catalyst base layer 11 a having a thickness of 1 μm was formed on the substrate 13. Next, a suspension was prepared by adding fine powder of titanium calcium phosphate hydroxyapatite to deionized water, and a predetermined amount of polyvinyl alcohol (PVA) as a binder was added to the suspension to form a paste. Next, the paste was dropped onto the catalyst base layer 11a, and the paste thin film was formed on the catalyst base layer 11a by spreading it while scraping the paste with a squeegee using an adhesive tape as a spacer. Next, after drying a paste thin film, it baked at 450 degreeC and the photocatalyst layer 11b was formed. Next, as described above, the second electrode 12 was formed to obtain the hydrogen generator 10.

  The hydrogen generator 10 was immersed in an aqueous solution containing an organic substance, and the generated hydrogen was measured as follows.

  First, in a borosilicate glass vacuum-compatible container, a 1 mol / L potassium nitrate aqueous solution added with 20% by volume of methanol was placed as an electrolyte, and the hydrogen generator 10 was immersed in the container.

  Next, after evacuating the inside of the container, freeze deaeration and evacuation were repeated to remove dissolved gas from the electrolyte.

Next, the photocatalyst layer 11b of the hydrogen generator 10 was irradiated with ultraviolet light for 10 hours using a xenon lamp. The irradiation power density was about 50 mW / cm ² in the total wavelength region including ultraviolet light to visible light. Borosilicate glass blocks visible light and long wavelength ultraviolet light by blocking short wavelength ultraviolet light that directly decomposes methanol.

  Freeze and deaerate the electrolyte in the container and collect the dissolved gas in the vacuum part of the container, freeze the electrolyte again, and sufficiently reduce the vapor pressure of water and methanol, so that only the generated gas is made into a vacuum system. Introduced. The gas introduced into the vacuum system was analyzed using a quadrupole mass spectrometer.

  As shown in FIG. 3, generation of hydrogen was confirmed when the thickness of the photocatalyst layer 11b was 1 μm and 2 μm.

  On the other hand, when the thickness of the photocatalyst layer 11b was 10 μm or more, the production of hydrogen was not measured. ND means Not Detected.

  The measurement result of the generated gas measured when the thickness of the photocatalyst layer 11b described above is 1 μm will be described below.

  FIG. 4 is a diagram showing a mass analysis result of the product gas.

  FIG. 4A shows the measurement results before introducing the product gas into the quadrupole mass spectrometer, and FIG. 4B shows the measurement results of the product gas.

  As shown in FIG. 4B, the product gas shows the presence of hydrogen atoms at the position of mass number / charge = 1, and the presence of hydrogen molecules at the position of mass number / charge = 2. It is shown. Although the partial pressures of these hydrogen atoms and hydrogen molecules are also shown in FIG. 4A, the partial pressure value is larger in FIG. 4B, so that hydrogen is generated. In addition, although the substance resulting from water and its decomposition product is shown in the position of mass number / charge = 16-18, the measurement partial pressure of FIG. 4 (B) and the measurement part of FIG. 4 (A) are shown. Pressure is of similar magnitude.

  According to the hydrogen generator 10 of the present embodiment described above, hydrogen can be generated. The hydrogen generator 10 has a high hydrogen generation capability because the photocatalyst layer 11b is formed of Ti apatite having a high adsorptive power.

  Moreover, since the photocatalyst layer 11b can be formed without using an adsorption auxiliary material, the first electrode 11 can be easily formed.

  Next, a second embodiment of the hydrogen generator described above will be described below with reference to FIGS. For points that are not particularly described in the other embodiments, the description in detail regarding the first embodiment is applied as appropriate. Moreover, the same code | symbol is attached | subjected to the same component.

  FIG. 5 is a diagram illustrating a second embodiment of the hydrogen generator disclosed in this specification. FIG. 6 is a diagram for explaining the reaction of the electrodes.

  The hydrogen generator 10 of this embodiment irradiates light to the electrode which has a catalyst, oxidizes the organic substance in factory wastewater, and produces | generates hydrogen.

  As shown in FIG. 5, the hydrogen generator 10 includes a first tank 14 that stores an aqueous solution containing an organic substance, and a second tank 15 that stores an aqueous solution. The first electrode 11 is disposed in the first tank 14, and the second electrode 12 is disposed in the second tank 15. The second tank 15 initially contains water.

  The 1st tank 14 and the 2nd tank 15 are connected so that the ion in aqueous solution can move using the connecting pipe 16. FIG.

  The first electrode 11 and the second electrode 12 are electrically connected by a wiring 17.

  The first tank 14 includes an inflow portion 18 into which factory wastewater flows and an outflow portion 19 through which the factory wastewater flows out to a river or the like.

  Moreover, the 1st tank 14 is provided with the window part 21 which permeate | transmits sunlight inside.

  The first electrode 11 in which the catalyst base layer 11a and the photocatalyst layer 11b are laminated on the substrate 13 is disposed in the first tank 14 with the photocatalyst layer 11b facing the window portion 21 side. This first tank 14 may be called a septic tank.

  In the second tank 15, liquid such as water or factory waste water is accommodated, and the second electrode 12 is immersed in the liquid.

  Above the second tank 15, a hydrogen outflow portion 20 connected to a hydrogen tank (not shown) is provided. Since the second tank 15 is separate from the first tank 14, it is easy to collect the hydrogen generated by the second electrode 12. This second tank 15 may be called a hydrogen generation tank.

  Next, a reaction example on the surfaces of the first electrode 11 and the second electrode 12 when sunlight is irradiated to the photocatalyst layer 11b disposed in the first tank 14 with reference to FIG. This will be described below.

  Examples of organic substances contained in factory wastewater include methane, acetone, methanol, ethanol, benzene, and the like.

In the first electrode 11a, there is an organic substance adsorbed on the surface of the photocatalyst layer 11b. In the photocatalyst layer 11b that has been irradiated with light, an electron e ⁻ .hole h ⁺ pair is generated, the hole h ⁺ is bonded to the organic substance, the organic substance is oxidized, and an oxidant of the organic substance ⁺ is formed on the surface of the photocatalytic layer 11b. Generate.

On the surface of the photocatalytic layer 11b, H ₂ O reacts with holes h ⁺ to generate active oxygen. Organic substances may be oxidized by reacting with this active oxygen. A part of the organic oxidant ⁺ further proceeds to generate CO ₂ or H ₂ O.

In the first electrode 11, among the generated electron e ⁻ .hole h ⁺ pairs, the hole h ⁺ is consumed to oxidize the organic matter, so that recombination of the electrons e ⁻ with the hole h ⁺ is suppressed. . Then, the electrons e ⁻ move to the second electrode 12 through the wiring 17.

On the other hand, on the surface of the second electrode 12, there is H ⁺ (a) on which H ⁺ generated on the surface of the first electrode 11a is adsorbed. This H ⁺ (a) combines with H ₂ O and is in equilibrium with H ₃ O ⁺ .

In the second electrode 12, the electrons e ⁻ generated in the photocatalyst layer 11b move to H ⁺ (a), and H ₂ is generated. In this way, the second electrode 12 generates hydrogen by reducing water.

In the second electrode 12, OH ⁻ is generated when water is reduced to generate hydrogen. The concentration of OH ⁻ increases with hydrogen production. As the OH ⁻ concentration in the second tank 15 increases, the hydrogen generation rate decreases, and therefore, from the second tank 15 having a high OH ⁻ concentration to the first tank 14 having a low concentration using a concentration gradient as a driving force. , OH ⁻ can be moved through the connecting pipe 16 to suppress an increase in OH ⁻ concentration in the second tank 15. The first tank 14 and the second tank 15 do not have to be connected using the connection pipe 16, but the liquid in the first tank 14 and the liquid in the second tank 15 are somehow used. Must be electrically connected to each other. As a method for that purpose, for example, a method of connecting both tanks with a salt bridge is conceivable.

An aqueous solution may be driven between the first tank 14 and the second tank 15 using a pump or the like to adjust the concentration of OH ⁻ .

  According to the hydrogen generator 10 of the present embodiment described above, hydrogen can be efficiently generated and collected. Moreover, according to the hydrogen generator 10, the same effect as the first embodiment described above can be obtained.

  In the present invention, the electrode, the hydrogen generator, and the method for generating hydrogen according to the above-described embodiments can be appropriately changed without departing from the gist of the present invention. In addition, the configuration requirements of one embodiment can be applied to other embodiments as appropriate.

  All examples and conditional words mentioned herein are intended for educational purposes to help the reader deepen and understand the inventions and concepts contributed by the inventor. All examples and conditional words mentioned herein are to be construed without limitation to such specifically stated examples and conditions. Also, such exemplary mechanisms in the specification are not related to showing the superiority and inferiority of the present invention. While embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions or modifications can be made without departing from the spirit and scope of the invention.

DESCRIPTION OF SYMBOLS 10 Hydrogen generator 11 1st electrode 11a Catalyst base layer 11b Photocatalyst layer 12 2nd electrode 13 Board | substrate 14 1st tank 15 2nd tank 16 Connection pipe 17 Wiring 18 Inflow part 19 Outflow part 20 Hydrogen outflow part 21 Window part

Claims (7)

A catalyst underlayer formed of an ion-bonding conductor;
A photocatalytic layer formed of apatite containing titanium ions as metal ions and laminated on the catalyst underlayer;
A first electrode having:
A second electrode electrically connected to the first electrode and having a hydrogen generation catalyst function;
Bei to give a,
The ion-bonding conductor includes fluorine-added tin oxide, tin-added indium oxide, zinc oxide, or a carbide or nitride of a group 4, group 5, or group 6 transition metal,
The thickness of the said photocatalyst layer is a hydrogen generator which exists in the range of 50 nm-2 micrometers . The hydrogen generation apparatus according to claim 1 , wherein the catalyst underlayer includes an oxide semiconductor or a carbide or nitride of a transition metal. 3. The hydrogen generation apparatus according to claim 1, wherein the apatite has a metal ion in an apatite crystal structure being an alkaline earth metal ion, and all or a part thereof is substituted with a titanium ion. The said apatite is a hydrogen generator as described in any one of Claims 1-3 containing a phosphate or a vanadate. A first tank;
A second tank;
With
The first electrode is disposed in the first tank,
The second electrode is disposed in the second tank;
The hydrogen generator according to any one of claims 1 to 4 , wherein the first tank and the second tank are connected. A catalyst underlayer formed of an ion-bonding conductor;
A photocatalytic layer formed of apatite containing titanium ions as metal ions and laminated on the catalyst underlayer;
I have a,
The ion-bonding conductor includes fluorine-added tin oxide, tin-added indium oxide, zinc oxide, or a carbide or nitride of a group 4, group 5, or group 6 transition metal,
The thickness of the photocatalyst layer is an electrode in the range of 50 nm to 2 μm . An organic substance in an aqueous solution using a first electrode having a catalyst underlayer formed of an ion-bonding conductor and an apatite containing titanium ions as metal ions and having a photocatalyst layer laminated on the catalyst underlayer Oxidizing and
Using a second electrode electrically connected to the first electrode and having a hydrogen generation catalyst function to reduce water to produce hydrogen ;
Have
The ion-bonding conductor includes fluorine-added tin oxide, tin-added indium oxide, zinc oxide, or a carbide or nitride of a group 4, group 5, or group 6 transition metal,
The photocatalyst layer has a thickness in the range of 50 nm to 2 μm .

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