JP2011162428A - Apparatus and method for producing hydrogen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for producing hydrogen, which has high utilization efficiency of light, and produces hydrogen with high efficiency, and in which the hydrogen generation rate does not decrease. <P>SOLUTION: The apparatus for producing hydrogen includes: a photoelectric conversion section having a light receiving surface and a rear surface; and a first gas generation section and a second gas generation section, which are provided on the rear surface in parallel. In the first gas generation section and the second gas generation section, one of the sections is a hydrogen generation section for generating H<SB>2</SB>from an electrolytic solution, and the other is an oxygen generation section for generating O<SB>2</SB>from the electrolytic solution. At least one of the first gas generation section and the second gas generation section is constituted of a plurality of sections. The first gas generation section is electrically connected with the rear surface, and the second gas generation section is electrically connected to the light receiving surface through a first electroconductive part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hydrogen production apparatus and a hydrogen production method.

  In recent years, the use of renewable energy has been desired from the viewpoint of depletion of fossil fuel resources and the suppression of global warming gas emissions. There are a wide variety of renewable energy sources such as sunlight, hydropower, wind power, geothermal power, tidal power, and biomass. Among them, sunlight has a large amount of available energy, and there are geographical constraints on other renewable energy. Because of the relatively small amount, early development and popularization of technology that can efficiently use energy from sunlight is desired.

  Possible forms of energy generated from sunlight include electrical energy produced using solar cells and solar thermal turbines, thermal energy by collecting solar energy in a heat medium, and other types of sunlight. Examples include storable fuel energy such as liquid fuel and hydrogen by substance reduction. Many solar cell technologies and solar heat utilization technologies have already been put into practical use, but the energy utilization efficiency is still low, and the cost of producing electricity and heat is still high. Technology development is underway. Furthermore, while these forms of electricity and heat can be used to supplement short-term energy fluctuations, it is extremely difficult to supplement long-term fluctuations such as seasonal fluctuations, It is a problem that there is a possibility that the operating rate of the power generation equipment may be reduced due to the increase in power generation. On the other hand, storing energy as a substance, such as liquid fuel and hydrogen, is extremely effective as a technology that efficiently supplements long-term fluctuations and increases the operating rate of power generation facilities. It is an indispensable technology to raise and reduce carbon dioxide emissions thoroughly.

  The types of fuel that can be stored are roughly divided into liquid fuels such as hydrocarbons, gaseous fuels such as biogas and hydrogen, solid pellets such as biomass-derived wood pellets and metals reduced by sunlight. it can. In terms of ease of infrastructure development and energy density, liquid fuel, gaseous fuel including hydrogen in terms of total utilization efficiency improvement with fuel cells, etc., solid fuel in terms of storability and energy density, Although each form has advantages and disadvantages, a hydrogen production technique by decomposing water with sunlight has attracted particular attention from the viewpoint that water that can be easily obtained as a raw material can be used.

  As a method of producing hydrogen using solar energy using water as a raw material, platinum is supported on a photocatalyst such as titanium oxide, and this substance is put in water to perform light separation in a semiconductor, and an electrolytic solution. The water is decomposed directly at high temperature using the photolysis method by reducing protons and oxidizing water, or by using thermal energy such as a high-temperature gas furnace, or indirectly by coupling with redox of metals, etc. Pyrolysis method that uses the metabolism of microorganisms that use light such as algae, water electrolysis method that combines electricity generated by solar cells and water electrolysis hydrogen production equipment, photoelectric conversion used in solar cells Examples of the method include a photovoltaic method in which electrons and holes obtained by photoelectric conversion are used in a reaction by a hydrogen generation catalyst and an oxygen generation catalyst by supporting a hydrogen generation catalyst and an oxygen generation catalyst on the material. Among these, the one that has the possibility of producing a small hydrogen production device by integrating the photoelectric conversion unit and the hydrogen generation unit is considered to be a photolysis method, a biological method, a photovoltaic method, From the viewpoint of the conversion efficiency of solar energy, the photovoltaic method is considered to be one of the technologies closest to practical use.

Until now, the example of the hydrogen production apparatus which integrated photoelectric conversion and hydrogen generation by the photolysis method or the photovoltaic method has been disclosed. In the photolysis method, for example, according to Patent Document 1, a titanium oxide photocatalyst electrode on which a ruthenium complex is adsorbed and a platinum electrode, an apparatus using oxidation reduction of iodine or iron is disclosed. According to Patent Documents 2 and 3, an integrated structure is adopted by connecting two layers of photocatalysts in tandem, connecting a platinum counter electrode, and sandwiching an ion exchange membrane therebetween. On the other hand, in the photovoltaic method, a concept of a hydrogen production apparatus in which a photoelectric conversion unit, a hydrogen generation unit, and an oxygen generation unit are integrated has been announced (Non-Patent Document 1). According to this, charge separation is performed by using a photoelectric conversion unit, and hydrogen generation and oxygen generation are performed using corresponding catalysts. The photoelectric conversion part is made of a material used for solar cells. For example, in Non-Patent Document 2, after charge separation is performed with three silicon pin layers, hydrogen generation is performed by a platinum catalyst, and oxygen generation is performed by ruthenium oxide. Further, in Non-Patent Document 3, a multi-junction photoelectric conversion material that absorbs light of different wavelengths is used by using Pt as a hydrogen generation catalyst and RuO ₂ as an oxygen generation catalyst to achieve high efficiency. In Patent Document 4 and Non-Patent Document 3, a hydrogen generation catalyst (NiFeO) and three layers of silicon pin are stacked in parallel on a substrate, and an oxygen generation catalyst (Co-Mo) is further formed on the silicon layer. ) To produce an integrated hydrogen production apparatus.

JP 2006-89336 A Special table 2003-504799 gazette Special table 2004-504934 gazette JP 2003-288955 A

Proceedings of the National Academy of Sciences of the United States of America, 2006, 43, 15729-15735 Applied Physics Letters, 1989, 55, 386-387. Journal of Physical Chemistry, 2009, 113, 14575-14581 International Journal of Hydrogen Energy, 2003, 28, 1167-1169.

As described above, several studies on the structure of a hydrogen production system that integrates photoelectric conversion and hydrogen generation have already been disclosed, but in order to produce hydrogen with higher efficiency, the light utilization rate is maximized. It is necessary to increase. For example, when gas is generated on the light-receiving surface in the apparatus, incident light is scattered by the generated gas, so that incident light cannot be used sufficiently, leading to a reduction in light utilization efficiency. Furthermore, when a catalyst is carried on the light receiving surface of the photoelectric conversion unit, incident light is reflected or absorbed by the catalyst, and this also causes a problem that the light utilization rate is lowered. In addition, a method of electrically connecting the light receiving surface of the photoelectric conversion unit and the oxygen catalyst with an electrode film so as to prevent light scattering has been studied, but the area of the photoelectric conversion unit is structurally different from other members. Since it is limited by the area (such as an oxygen generation catalyst), it is difficult to avoid a decrease in the light utilization rate. In particular, with the increase in size of the device, the problem is that the hydrogen generation rate decreases due to the proton concentration imbalance between the electrolyte near the hydrogen generation catalyst and the electrolyte near the oxygen generation catalyst. It has become.
The present invention has been made in view of such circumstances, and provides a hydrogen production apparatus that has high light utilization efficiency, can produce hydrogen with high efficiency, and does not reduce the hydrogen generation rate.

The present invention includes a photoelectric conversion unit having a light receiving surface and a back surface, and a first gas generation unit and a second gas generation unit provided in parallel on the back surface, the first gas generation unit and the first gas generation unit Of the two gas generation units, one is a hydrogen generation unit that generates H ₂ from the electrolytic solution, and the other is an oxygen generation unit that generates O ₂ from the electrolytic solution, and the first gas generation unit and the second gas generation unit At least one of the gas generating units is plural, the first gas generating unit is electrically connected to the back surface, and the second gas generating unit is electrically connected to the light receiving surface via the first conductive unit. Provided is a hydrogen production apparatus characterized by being connected.

According to the present invention, an electromotive force can be generated in the photoelectric conversion unit by causing light to enter the light receiving surface of the photoelectric conversion unit, and a potential difference can be generated between the light receiving surface and the back surface. Accordingly, the first gas generation unit electrically connected to the back surface of the photoelectric conversion unit, the second gas generation unit electrically connected to the light receiving surface of the photoelectric conversion unit via the first conductive unit, and A potential difference can be generated between the two. By bringing the electrolytic solution into contact with the first gas generating unit and the second gas generating unit in which this potential difference has occurred, either the first gas generating unit or the second gas generating unit is used as the electrolytic solution. Can generate H ₂ , while O ₂ can be generated from the electrolyte. By recovering the generated H ₂ , hydrogen can be produced.

According to the present invention, since the hydrogen generation unit and the oxygen generation unit are provided on the back surface of the photoelectric conversion unit, light can be incident on the light receiving surface without passing through the electrolytic solution. Can be prevented. As a result, the amount of incident light to the photoelectric conversion unit can be increased, and the light use efficiency can be increased.
In addition, according to the present invention, since the hydrogen generation unit and the oxygen generation unit are provided on the back surface of the photoelectric conversion unit, the light incident on the light receiving surface is generated by the hydrogen generation unit and the oxygen generation unit, and the hydrogen and It is not absorbed or scattered by oxygen. As a result, the amount of incident light to the photoelectric conversion unit can be increased, and the light use efficiency can be increased.

According to the present invention, since the hydrogen generation unit and the oxygen generation unit are provided on the back surface of the photoelectric conversion unit, the light receiving surface of the photoelectric conversion unit can be provided on most of the surface on which the hydrogen production apparatus receives light. Thereby, the light utilization efficiency can be further increased.
Further, according to the present invention, since the photoelectric conversion unit, the hydrogen generation unit, and the oxygen generation unit are provided in the same device, the hydrogen production cost is higher than the combination of the conventional solar cell and water electrolysis device. Can be reduced.
Further, according to the present invention, since the second gas generation unit and the light receiving surface of the photoelectric conversion unit are electrically connected via the first conductive unit, the photoelectric conversion unit has a structure made of a uniform material over the entire surface. can do. For this reason, the light-receiving surface of a photoelectric conversion part can be enlarged, and the manufacturing cost of a hydrogen production apparatus can be reduced.
Further, according to the present invention, at least one of the first gas generation unit and the second gas generation unit is plural and provided in parallel. As a result, the portion where the first gas generating unit and the second gas generating unit are adjacent to each other is increased, and the gap between the electrolyte near the first gas generating unit and the electrolyte near the second gas generating unit is increased. Proton ion conduction distance can be shortened. Further, the number of proton conduction paths of the electrolyte solution or ion exchanger through which protons conduct ions can be increased, and the ratio of proton conduction regions can be increased. As a result, the concentration of the conductive proton can be reduced.
This facilitates movement of protons in the electrolyte solution in the vicinity of the first gas generation part and the electrolyte solution in the vicinity of the second gas generation part, and the proton concentration imbalance can be reduced. As a result, a decrease in hydrogen generation rate can be prevented. Furthermore, even if the hydrogen production apparatus is enlarged and the amount of hydrogen produced increases, it is possible to prevent a decrease in the hydrogen generation rate due to an imbalance in proton concentration. In addition, proton movement between the electrolyte solution near the first gas generation unit and the electrolyte solution near the second gas generation unit may be rate-limiting in the hydrogen generation reaction, and therefore protons can be easily transferred. Thus, the speed of the hydrogen generation reaction can be maximized.

It is a schematic plan view which shows the structure of the hydrogen production apparatus of one Embodiment of this invention. It is a schematic sectional drawing of the dotted line AA of FIG. It is a schematic back view which shows the structure of the hydrogen production apparatus of one Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the hydrogen production apparatus of one Embodiment of this invention. It is a schematic plan view which shows the structure of the hydrogen production apparatus of one Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the hydrogen production apparatus of one Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the hydrogen production apparatus of one Embodiment of this invention. It is a schematic plan view which shows the structure of the hydrogen production apparatus of one Embodiment of this invention.

The hydrogen production apparatus of the present invention includes a photoelectric conversion unit having a light receiving surface and a back surface, a first gas generation unit and a second gas generation unit provided in parallel on the back surface, and a first gas One of the generation unit and the second gas generation unit is a hydrogen generation unit that generates H ₂ from the electrolytic solution, and the other is an oxygen generation unit that generates O ₂ from the electrolytic solution, and the first gas generation unit And at least one of the second gas generation units is plural, the first gas generation unit is electrically connected to the back surface, and the second gas generation unit is connected to the light receiving surface via the first conductive unit. It is characterized by being electrically connected to.

A hydrogen production apparatus is an apparatus that can produce hydrogen from an electrolyte containing water.
The photoelectric conversion part is a part that receives light and generates an electromotive force.
The light receiving surface is a surface of the photoelectric conversion unit on which light is incident.
The back surface is the back surface of the light receiving surface.

In the hydrogen production apparatus of the present invention, it is preferable that the first gas generation unit and the second gas generation unit are provided so as to be alternately arranged.
According to such a configuration, it is possible to further shorten the distance of proton conduction between the electrolyte near the first gas generator and the electrolyte near the second gas generator.
In the hydrogen production apparatus of the present invention, it is preferable that a partition wall is further provided between the first gas generation unit and the second gas generation unit.
According to such a configuration, hydrogen and oxygen generated in the first gas generation unit and the second gas generation unit can be separated, and hydrogen can be recovered more efficiently.
In the hydrogen production apparatus of the present invention, the partition wall is preferably provided so as to partition the first gas generation unit and the second gas generation unit.
According to such a configuration, hydrogen can be recovered more efficiently.

In the hydrogen production apparatus of the present invention, the first gas generation unit and the second gas generation unit are preferably substantially rectangular, and are provided so that the long sides are adjacent to each other with the partition wall in between. Is preferred.
According to such a configuration, it is possible to further shorten the distance of proton conduction between the electrolyte near the first gas generator and the electrolyte near the second gas generator. Moreover, the area | region which forms a 1st gas generation part and a 2nd gas generation part can be enlarged, and hydrogen generation amount can be increased more. In addition, the generated hydrogen or oxygen can be easily recovered by providing a substantially rectangular shape and sandwiching the partition wall.
In the hydrogen production apparatus of the present invention, the first gas discharge port provided outside one short side of the first gas generation unit and the first gas discharge port provided outside one short side of the second gas generation unit. It is preferable to further include two gas discharge ports, and the first gas discharge port and the second gas discharge port are preferably provided side by side.
According to such a configuration, the generated hydrogen or oxygen can be easily recovered.

In the hydrogen production apparatus of the present invention, there are a plurality of first gas discharge ports and a plurality of second gas discharge ports, and the plurality of first gas discharge ports are electrically connected to one first gas discharge path, and a plurality of first gas discharge ports are provided. The outlet is preferably connected to one second gas discharge path.
According to such a configuration, the generated hydrogen or oxygen can be recovered more easily, and the convenience can be enhanced.
In the hydrogen production apparatus of the present invention, the partition preferably includes an ion exchanger.
According to such a configuration, the proton concentration imbalance between the electrolyte introduced into the space above the first gas generator and the electrolyte introduced into the space above the second gas generator. Can be eliminated, and hydrogen and oxygen can be generated stably.

In the hydrogen production apparatus of the present invention, it is preferable that the second gas generation unit is provided on the back surface through an insulating unit.
According to such a configuration, it is possible to prevent leakage current from flowing between the second gas generation unit and the back surface of the photoelectric conversion unit.
In the hydrogen production apparatus of the present invention, it is preferable to further include a second electrode provided between the back surface and the first gas generation unit.
According to such a configuration, the current flowing between the back surface of the photoelectric conversion unit and the first gas generation unit can be increased by the electromotive force of the photoelectric conversion unit, and hydrogen or oxygen can be generated more efficiently. Can do.

In the hydrogen production apparatus of the present invention, it is preferable that the second electrode and the insulating portion have corrosion resistance and liquid shielding properties against the electrolytic solution.
According to such a configuration, contact between the photoelectric conversion unit and the electrolytic solution can be prevented, and corrosion of the photoelectric conversion unit due to the electrolytic solution can be prevented.
In the hydrogen production apparatus of the present invention, the first conductive part includes a first electrode that contacts the light receiving surface, and a second conductive part that contacts the first electrode and the second gas generation part, respectively. preferable.
According to such a configuration, the light receiving surface of the photoelectric conversion unit and the second gas generation unit can be electrically connected, and hydrogen or oxygen can be generated more efficiently.

In the hydrogen production apparatus of the present invention, it is preferable that the second conductive portion is provided in a contact hole that penetrates the photoelectric conversion portion.
According to such a configuration, the first electrode and the second gas generation unit can be electrically connected, and the reduction in the area of the light receiving surface of the photoelectric conversion unit due to the provision of the second conductive unit is reduced. can do.
In the hydrogen production apparatus of the present invention, the second conductive portion has a cross section parallel to the light receiving surface, and the cross section is an elongated shape parallel to the column direction of the first gas generating portion and the second gas generating portion. It is preferable to have.
According to such a configuration, it is possible to further reduce the potential drop caused by the movement of electric charge between the light receiving surface of the photoelectric conversion unit and the second gas generation unit.

In the hydrogen production apparatus of the present invention, the photoelectric conversion unit is preferably provided on a light-transmitting substrate.
According to such a structure, the photoelectric conversion part which needs to be formed on a board | substrate can be applied to the hydrogen production apparatus of this invention. In addition, the hydrogen production apparatus of the present invention can be easily handled.

In the hydrogen production apparatus of the present invention, the photoelectric conversion unit preferably has a photoelectric conversion layer composed of a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer.
According to such a configuration, the photoelectric conversion unit can have a pin structure, and photoelectric conversion can be performed efficiently. Moreover, the electromotive force generated in the photoelectric conversion unit can be increased, and the electrolytic solution can be electrolyzed more efficiently.

In the hydrogen production apparatus of the present invention, it is preferable that each of the hydrogen generation unit and the oxygen generation unit includes a catalyst for a reaction for generating H ₂ from the electrolytic solution and a catalyst for a reaction for generating O ₂ from the electrolytic solution.
According to such a configuration, the reaction rate of the reaction in which H ₂ is generated from the electrolytic solution in the hydrogen generation unit can be increased, and the reaction rate of the reaction in which O ₂ is generated from the electrolytic solution in the oxygen generation unit is increased. be able to. Thus, H ₂ can be more efficiently produced by the electromotive force generated in the photoelectric conversion unit, and the light utilization efficiency can be improved.
In the hydrogen production apparatus of the present invention, it is preferable that at least one of the hydrogen generation part and the oxygen generation part is a porous conductor carrying a catalyst.
According to such a configuration, the surface area of at least one of the first gas generation unit and the second gas generation unit can be increased, and oxygen or hydrogen can be generated more efficiently. In addition, by using a porous conductor, a change in potential due to a current flowing between the photoelectric conversion unit and the catalyst can be suppressed, and hydrogen or oxygen can be generated more efficiently.

In the hydrogen production apparatus of the present invention, the photoelectric conversion unit is provided on a light-transmitting substrate, and a top plate facing the substrate is provided on the first gas generation unit and the second gas generation unit. Further, it is preferable that a space is provided between the first gas generation unit and the second gas generation unit and the top plate.
According to such a configuration, the electrolytic solution can be introduced between the first gas generation unit and the second gas generation unit and the top plate, and the first gas generation unit and the second gas generation H ₂ and O ₂ can be more efficiently generated from the electrolytic solution in the part.

In the hydrogen production apparatus of the present invention, a partition is further provided between the first gas generation unit and the second gas generation unit, and the partition includes a space between the first gas generation unit and the top plate, and It is preferable to be provided so as to partition the space between the second gas generation unit and the top plate.
According to such a configuration, hydrogen and oxygen generated in the first gas generation unit and the second gas generation unit can be separated, and hydrogen can be recovered more efficiently.

In the present invention, the hydrogen production apparatus of the present invention is installed such that the light receiving surface is inclined with respect to a horizontal plane, an electrolyte is introduced into the hydrogen production apparatus from a lower part of the hydrogen production apparatus, and sunlight is received. There is also provided a hydrogen production method in which hydrogen and oxygen are respectively generated from the hydrogen generation unit and the oxygen generation unit by being incident on a surface, and hydrogen and oxygen are discharged from an upper part of the hydrogen production apparatus.
According to the hydrogen production method of the present invention, hydrogen can be produced at low cost using sunlight.

  The present invention will be described below with reference to embodiments shown in the drawings. The configurations shown in the drawings and the following description are merely examples, and the scope of the present invention is not limited to those shown in the drawings and the following description.

Configuration of Hydrogen Production Device FIG. 1 shows a configuration of a hydrogen production device according to an embodiment of the present invention, and is a schematic plan view seen from the light receiving surface side of a photoelectric conversion unit. 2 is a schematic cross-sectional view taken along a dotted line AA in FIG. FIG. 3 shows a configuration of the hydrogen production apparatus according to the embodiment of the present invention, and is a schematic back view seen from the back side of the photoelectric conversion unit.

The hydrogen production apparatus 23 of this embodiment includes a photoelectric conversion unit 2 having a light receiving surface and a back surface, and a first gas generation unit 8 and a second gas generation unit 7 provided in parallel on the back surface. One of the first gas generation unit 8 and the second gas generation unit 7 is a hydrogen generation unit that generates H ₂ from the electrolytic solution, and the other is an oxygen generation unit that generates O ₂ from the electrolytic solution. At least one of the first gas generation unit 8 and the second gas generation unit 7 is plural, the first gas generation unit 8 is electrically connected to the back surface, and the second gas generation unit 7 is It is electrically connected to the light receiving surface via the first conductive portion 9.

In addition, the first conductive unit 9 included in the hydrogen production apparatus 23 of the present embodiment may include the first electrode 4 and the second conductive unit 10. Further, the hydrogen production apparatus 23 of the present embodiment includes the substrate 1, the second electrode 5, the insulating portion 11, the partition wall 13, the top plate 14, the electrolyte flow path 15, the sealing material 16, the water supply port 18, and the first gas discharge port. 20, a second gas discharge port 19, a first gas discharge path 25, and a second gas discharge path 26 may be provided.
Hereinafter, the hydrogen production apparatus of this embodiment will be described.

1. Substrate The substrate 1 may be provided in the hydrogen production apparatus 23 of the present embodiment. Moreover, the photoelectric conversion part 2 may be provided on the translucent board | substrate 1 so that a light-receiving surface may become the board | substrate 1 side. In addition, when the photoelectric conversion part 2 consists of semiconductor substrates etc. and has fixed intensity | strength, the board | substrate 1 can be abbreviate | omitted. Moreover, when the photoelectric conversion part 2 can be formed on a flexible material such as a resin film, the substrate 1 can be omitted.

Moreover, the board | substrate 1 is a member used as the foundation for comprising this hydrogen production apparatus. Moreover, in order to receive sunlight with the light-receiving surface of the photoelectric conversion unit 2, it is preferable to be transparent and have a high light transmittance. However, as long as the light can be efficiently incident on the photoelectric conversion unit 2. There is no limit to the light transmittance.
As a substrate material having a high light transmittance, for example, a transparent rigid material such as soda glass, quartz glass, Pyrex (registered trademark), or a synthetic quartz plate, or a transparent resin plate or film material is preferably used. In view of chemical and physical stability, it is preferable to use a glass substrate.
On the surface of the substrate 1 on the photoelectric conversion unit 2 side, a fine uneven structure can be formed so that incident light is effectively diffusely reflected on the surface of the photoelectric conversion unit 2. This fine concavo-convex structure can be formed by a known method such as reactive ion etching (RIE) treatment or blast treatment.

2. First Conductive Unit The first conductive unit 9 electrically connects the second gas generating unit 7 and the light receiving surface of the photoelectric conversion unit 2. Further, the first conductive portion 9 may be composed of one member, or may be composed of the first electrode 4 and the second conductive portion 10. By providing the first conductive portion 9, the potential of the light receiving surface of the photoelectric conversion portion 2 and the potential of the second gas generation portion 7 can be made substantially the same, and hydrogen or oxygen can be generated in the second gas generation portion 7. Can be generated.
Examples of the case where the first conductive portion 9 is made of one member include metal wiring that electrically connects the light receiving surface of the photoelectric conversion portion 2 and the second gas generation portion 7. For example, it is a metal wiring made of Ag. Further, the metal wiring may have a shape like a finger electrode so as not to reduce light incident on the photoelectric conversion unit 2. The first conductive unit 9 may be provided on the photoelectric conversion unit 2 side of the substrate 1 or may be provided on the light receiving surface of the photoelectric conversion unit 2.

3. 1st electrode The 1st electrode 4 can be provided on the board | substrate 1, and can be provided so that the light-receiving surface of the photoelectric conversion part 2 may be contacted. Moreover, the 1st electrode 4 may have translucency. Moreover, the 1st electrode 4 may be directly provided in the light-receiving surface of the photoelectric conversion part 2, when the board | substrate 1 can be abbreviate | omitted. By providing the first electrode 4, the current flowing between the light receiving surface of the photoelectric conversion unit 2 and the second gas generation unit 7 can be increased.
The first electrode 4 may be made of a transparent conductive film such as ITO or SnO _2, or may be made of a metal finger electrode such as Ag or Au.

A case where the first electrode 4 is a transparent conductive film will be described below.
The transparent conductive film is used to facilitate contact between the light receiving surface of the photoelectric conversion unit 2 and the second gas generation unit 7.
What is generally used as a transparent electrode can be used. Specifically, In—Zn—O (IZO), In—Sn—O (ITO), ZnO—Al, Zn—Sn—O, SnO _{2 and the} like can be given. The transparent conductive film preferably has a sunlight transmittance of 85% or more, particularly 90% or more, and particularly 92% or more. This is because the photoelectric conversion unit 2 can absorb light efficiently.
As a method for producing the transparent conductive film, a known method can be used, and examples thereof include sputtering, vacuum deposition, sol-gel method, cluster beam deposition method, and PLD (Pulse Laser Deposition) method.

4). Photoelectric Conversion Unit The photoelectric conversion unit 2 has a light receiving surface and a back surface, and a first gas generation unit 8 and a second gas generation unit 7 are provided in parallel on the back surface of the photoelectric conversion unit 2. The light receiving surface is a surface that receives light for photoelectric conversion, and the back surface is the back surface of the light receiving surface. The photoelectric conversion unit 2 can be provided on the substrate 1 on which the first electrode 4 is provided with the light receiving surface facing down.
Although the shape of the photoelectric conversion part 2 is not specifically limited, For example, it is substantially square. When the photoelectric conversion unit 2 is substantially square, the first gas generation unit 8 having a certain width and the second gas generation unit 7 having a certain width are arranged in parallel with one side of the photoelectric conversion unit. be able to. In this case, the width of the photoelectric conversion unit 2 in the direction in which the first gas generation unit 8 and the second gas generation unit 7 are arranged is, for example, 50 cm or more and 200 cm or less. As a result, the size of the hydrogen production apparatus can be increased, and the amount of hydrogen generation can be increased. Moreover, the width | variety of the photoelectric conversion part 2 of the direction perpendicular | vertical to the direction where the 1st gas generation part 8 and the 2nd gas generation part 7 were located is 50 cm or more and 200 cm or less, for example.

  The photoelectric conversion unit 2 is not particularly limited as long as it can perform charge separation by incident light and generates an electromotive force between the light receiving surface and the back surface. For example, the photoelectric conversion unit using a silicon-based semiconductor, A photoelectric conversion unit using a compound semiconductor, a photoelectric conversion unit using a dye sensitizer, a photoelectric conversion unit using an organic thin film, and the like.

  The photoelectric conversion unit 2 needs to use a material that generates electromotive force necessary to generate hydrogen and oxygen in the hydrogen generation unit and the oxygen generation unit, respectively, by receiving light. The potential difference between the hydrogen generation unit and the oxygen generation unit needs to be larger than the theoretical voltage (1.23 V) for water splitting. For that purpose, it is necessary to generate a sufficiently large potential difference in the photoelectric conversion unit 2. Therefore, it is preferable that the photoelectric conversion unit 2 connects two or more junctions in series such as a pn junction to generate electromotive force.

  Examples of the material that performs photoelectric conversion include silicon-based semiconductors, compound semiconductors, and materials based on organic materials, and any photoelectric conversion material can be used. In order to increase the electromotive force, these photoelectric conversion materials can be stacked. In the case of stacking, it is possible to form a multi-junction structure with the same material, but stacking multiple photoelectric conversion layers with different optical band gaps and complementing the low sensitivity wavelength region of each photoelectric conversion layer mutually By doing so, incident light can be efficiently absorbed over a wide wavelength region. The plurality of photoelectric conversion layers preferably have different band gaps. According to such a configuration, the electromotive force generated in the photoelectric conversion unit can be further increased, and the electrolytic solution can be electrolyzed more efficiently.

Moreover, it is possible to interpose a conductor such as a transparent conductive film between the layers in order to improve the serial connection characteristics between the photoelectric conversion layers and to match the photocurrent generated in the photoelectric conversion unit 2. Thereby, it becomes possible to suppress deterioration of the photoelectric conversion unit 2.
An example of the photoelectric conversion unit 2 will be specifically described below. The photoelectric conversion unit 2 may be a combination of these.

4-1. Photoelectric conversion part using a silicon-based semiconductor Examples of the photoelectric conversion part 2 using a silicon-based semiconductor include a single crystal type, a polycrystalline type, an amorphous type, a spherical silicon type, and combinations thereof. Any of them can have a pn junction in which a p-type semiconductor and an n-type semiconductor are joined. Further, a pin junction in which an i-type semiconductor is provided between a p-type semiconductor and an n-type semiconductor may be provided. Further, it may have a plurality of pn junctions, a plurality of pin junctions, or a pn junction and a pin junction.
The silicon-based semiconductor is a semiconductor containing silicon, such as silicon, silicon carbide, or silicon germanium. In addition, silicon or the like in which n-type impurities or p-type impurities are added is included, and crystalline, amorphous, or microcrystalline silicon is also included.
The photoelectric conversion unit 2 using a silicon-based semiconductor may be a thin film or a thick photoelectric conversion layer formed on the substrate 1, and a pn junction or a pin junction is formed on a wafer such as a silicon wafer. A thin film photoelectric conversion layer may be formed on a wafer on which a pn junction or a pin junction is formed.

An example of forming the photoelectric conversion unit 2 using a silicon-based semiconductor is shown below.
A first conductivity type semiconductor layer is formed on the first electrode 4 stacked on the substrate 1 by a method such as a plasma CVD method. As the first conductive type semiconductor layer, a p + type or n + type amorphous Si thin film doped with a conductivity type determining impurity atom concentration of about 1 × 10 ^{18 to} 5 × 10 ²¹ / cm ³ , a polycrystalline or A microcrystalline Si thin film is used. The material of the first conductivity type semiconductor layer is not limited to Si, and it is also possible to use a compound such as SiC, SiGe, or Si _x O _1-x .

On the first conductivity type semiconductor layer thus formed, a polycrystalline or microcrystalline crystalline Si thin film is formed as a crystalline Si photoactive layer by a method such as plasma CVD. The conductivity type is the first conductivity type having a lower doping concentration than the first conductivity type semiconductor, or the i conductivity type. The material for the crystalline Si-based photoactive layer is not limited to Si, and it is also possible to use a compound such as SiC, SiGe, or Si _x O _1-x .

Next, in order to form a semiconductor junction on the crystalline Si-based photoactive layer, a second conductivity type semiconductor layer having a conductivity type opposite to the first conductivity type semiconductor layer is formed by a method such as plasma CVD. As the second conductivity type semiconductor layer, an n + type or p + type amorphous Si thin film doped with about 1 × 10 ^{18 to} 5 × 10 ²¹ / cm ^{3 of} conductivity type determining impurity atoms, or a polycrystalline or microscopic A crystalline Si thin film is used. The material of the second conductivity type semiconductor layer is not limited to Si, and it is also possible to use a compound such as SiC, SiGe, or Si _x O _1-x . In order to further improve the bonding characteristics, it is possible to insert a substantially i-type non-single-crystal Si-based thin film between the crystalline Si-based photoactive layer and the second conductive type semiconductor layer. In this manner, one photoelectric conversion layer closest to the light receiving surface can be stacked.

  Subsequently, a second photoelectric conversion layer is formed. The second photoelectric conversion layer is composed of a first conductivity type semiconductor layer, a crystalline Si-based photoactive layer, and a second conductivity type semiconductor layer, each layer corresponding to the first photoelectric conversion layer. The first conductive type semiconductor layer, the crystalline Si-based photoactive layer, and the second conductive type semiconductor layer are formed. When a potential sufficient for water splitting cannot be obtained with a two-layer tandem, it is preferable to take a three-layer structure or more. However, the volume crystallization fraction of the crystalline Si photoactive layer of the second photoelectric conversion layer is preferably higher than that of the first crystalline Si photoactive layer. Similarly, when three or more layers are laminated, it is preferable to increase the volume crystallization fraction as compared with the lower layer. This increases the absorption in the long wavelength region, shifts the spectral sensitivity to the long wavelength side, and can improve the sensitivity in a wide wavelength region even when the photoactive layer is configured using the same Si material. It is because it becomes. That is, by using a tandem structure with Si having different crystallization rates, the spectral sensitivity is widened, and light can be used with high efficiency. At this time, if the low crystallization rate material is not on the light receiving surface side, high efficiency cannot be achieved. Further, when the crystallization rate is lowered to 40% or less, the amorphous component increases and deterioration occurs.

4-2. Photoelectric conversion part using compound semiconductor The photoelectric conversion part using a compound semiconductor is, for example, GaP, GaAs, InP, InAs, or IId-VI group elements composed of III-V group elements, CdTe / CdS, Examples thereof include those in which a pn junction is formed using CIGS (Copper Indium Gallium DiSelenide) composed of a group I-III-VI.

An example of a method for manufacturing a photoelectric conversion unit using a compound semiconductor is shown below. In this manufacturing method, all film forming processes and the like are continuously performed using a metal organic chemical vapor deposition (MOCVD) apparatus. Done. As a group III element material, for example, an organic metal such as trimethylgallium, trimethylaluminum, or trimethylindium is supplied to the growth apparatus using hydrogen as a carrier gas. For example, a gas such as arsine (AsH ₃ ), phosphine (PH ₃ ), and stibine (SbH ₃ ) is used as the material of the group V element. As a dopant of p-type impurities or n-type impurities, for example, diethyl zinc for p-type conversion, monosilane (SiH ₄ ), disilane (Si ₂ H ₆ ), hydrogen selenide (H ₂ Se) for n-type conversion. Etc. are used. These source gases can be thermally decomposed by supplying them onto a substrate heated to, for example, 700 ° C., and a desired compound semiconductor material film can be epitaxially grown. The composition of these growth layers can be controlled by the gas composition to be introduced, and the film thickness can be controlled by the gas introduction time. When multi-junction laminating these photoelectric conversion parts, it is possible to form a growth layer with excellent crystallinity by adjusting the lattice constant between layers as much as possible, and to improve the photoelectric conversion efficiency. Become.

  In addition to the portion where the pn junction is formed, for example, a known window layer on the light receiving surface side or a known electric field layer on the non-light receiving surface side may be provided to improve carrier collection efficiency. Further, a buffer layer for preventing diffusion of impurities may be provided.

4-3. Photoelectric conversion part using a dye sensitizer The photoelectric conversion part using a dye sensitizer is mainly composed of, for example, a porous semiconductor, a dye sensitizer, an electrolyte, a solvent, and the like.
As a material constituting the porous semiconductor, for example, one or more kinds of known semiconductors such as titanium oxide, tungsten oxide, zinc oxide, barium titanate, strontium titanate, cadmium sulfide can be selected. As a method for forming a porous semiconductor on a substrate, a paste containing semiconductor particles is applied by a screen printing method, an ink jet method and the like, dried or baked, a method of forming a film by a CVD method using a raw material gas, etc. , PVD method, vapor deposition method, sputtering method, sol-gel method, method using electrochemical oxidation-reduction reaction, and the like.

  As the dye sensitizer adsorbed on the porous semiconductor, various dyes having absorption in the visible light region and the infrared light region can be used. Here, in order to firmly adsorb the dye to the porous semiconductor, the carboxylic acid group, carboxylic anhydride group, alkoxy group, sulfonic acid group, hydroxyl group, hydroxylalkyl group, ester group, mercapto group, phosphonyl in the dye molecule It is preferable that a group or the like exists. These functional groups provide an electrical bond that facilitates electron transfer between the excited state dye and the conduction band of the porous semiconductor.

  Examples of dyes containing these functional groups include ruthenium bipyridine dyes, quinone dyes, quinone imine dyes, azo dyes, quinacridone dyes, squarylium dyes, cyanine dyes, merocyanine dyes, and triphenylmethane dyes. Xanthene dyes, porphyrin dyes, phthalocyanine dyes, berylene dyes, indigo dyes, naphthalocyanine dyes, and the like.

  Examples of the method for adsorbing the dye to the porous semiconductor include a method in which the porous semiconductor is immersed in a solution in which the dye is dissolved (dye adsorption solution). The solvent used in the dye adsorption solution is not particularly limited as long as it dissolves the dye, and specifically, alcohols such as ethanol and methanol, ketones such as acetone, ethers such as diethyl ether and tetrahydrofuran. Nitrogen compounds such as acetonitrile, aliphatic hydrocarbons such as hexane, aromatic hydrocarbons such as benzene, esters such as ethyl acetate, water, and the like.

The electrolyte is composed of a redox pair and a solid medium such as a liquid or polymer gel holding the redox pair.
In general, iron- and cobalt-based metals and halogen substances such as chlorine, bromine, and iodine are preferably used as the redox pair, and metal iodides such as lithium iodide, sodium iodide, and potassium iodide and iodine are used. The combination of is preferably used. Furthermore, imidazole salts such as dimethylpropylimidazole iodide can also be mixed.

  As the solvent, carbonate compounds such as propylene carbonate, nitrile compounds such as acetonitrile, alcohols such as ethanol and methanol, water, aprotic polar substances, and the like are used. Of these, carbonate compounds and nitrile compounds are preferred. Used.

4-4. Photoelectric conversion part using organic thin film A photoelectric conversion part using an organic thin film comprises an electron hole transport layer composed of an organic semiconductor material having electron donating properties and electron accepting properties, or an electron transport layer having electron accepting properties. It may be a laminate of a hole transport layer having an electron donating property.
The electron-donating organic semiconductor material is not particularly limited as long as it has a function as an electron donor, but it is preferable that a film can be formed by a coating method, and among them, an electron-donating conductive polymer is preferably used. The

  Here, the conductive polymer means a π-conjugated polymer, which is composed of a π-conjugated system in which double bonds or triple bonds containing carbon-carbon or hetero atoms are alternately linked to single bonds, and exhibits semiconducting properties. Point.

  Examples of the electron-donating conductive polymer material include polyphenylene, polyphenylene vinylene, polythiophene, polycarbazole, polyvinyl carbazole, polysilane, polyacetylene, polypyrrole, polyaniline, polyfluorene, polyvinyl pyrene, polyvinyl anthracene, and derivatives, Examples thereof include a polymer, a phthalocyanine-containing polymer, a carbazole-containing polymer, and an organometallic polymer. Among these, thiophene-fluorene copolymer, polyalkylthiophene, phenyleneethynylene-phenylene vinylene copolymer, fluorene-phenylene vinylene copolymer, thiophene-phenylene vinylene copolymer, and the like are preferably used.

The electron-accepting organic semiconductor material is not particularly limited as long as it has a function as an electron acceptor. However, it is preferable that a film can be formed by a coating method, and among them, an electron-donating conductive polymer is preferably used. The
Examples of the electron-accepting conductive polymer include polyphenylene vinylene, polyfluorene, and derivatives and copolymers thereof, or carbon nanotubes, fullerene and derivatives thereof, CN group or CF ₃ group-containing polymers, and -CF thereof. Examples thereof include _3- substituted polymers.

In addition, an electron-accepting organic semiconductor material doped with an electron-donating compound, an electron-donating organic semiconductor material doped with an electron-accepting compound, or the like can be used. Examples of the electron-accepting conductive polymer material doped with the electron-donating compound include the above-described electron-accepting conductive polymer material. As the electron-donating compound to be doped, for example, a Lewis base such as an alkali metal such as Li, K, Ca, or Cs or an alkaline earth metal can be used. The Lewis base acts as an electron donor. Examples of the electron-donating conductive polymer material doped with the electron-accepting compound include the above-described electron-donating conductive polymer material. As the electron-accepting compound to be doped, for example, a Lewis acid such as FeCl ₃ , AlCl ₃ , AlBr ₃ , AsF ₆ or a halogen compound can be used. In addition, Lewis acid acts as an electron acceptor.

  In the photoelectric conversion unit 2 shown above, it is assumed that sunlight is received and photoelectric conversion is primarily performed. However, it is emitted from a fluorescent lamp, an incandescent lamp, an LED, or a specific heat source depending on the application. It is also possible to perform photoelectric conversion by irradiating artificial light such as light.

5. Second Electrode The second electrode 5 can be provided between the photoelectric conversion unit 2 and the first gas generation unit 8. By providing the second electrode 5, the potential of the back surface of the photoelectric conversion unit 2 and the potential of the first gas generation unit 8 can be made substantially the same. Moreover, the ohmic cross between the back surface of the photoelectric conversion unit 2 and the first gas generation unit 8 can be reduced. Moreover, the electric current which flows between the back surface of the photoelectric conversion part 2 and the 1st gas generation part 8 can be enlarged. Thereby, hydrogen or oxygen can be more efficiently generated by the electromotive force generated in the photoelectric conversion unit 2. In addition, when it is possible to contact the back surface of the photoelectric conversion unit 2 and the first gas generation unit 8 with a small electric resistance, the second electrode 5 can be omitted. Moreover, it is preferable that the 2nd electrode 5 has the corrosion resistance with respect to electrolyte solution, and the liquid shielding property with respect to electrolyte solution. Thereby, corrosion of the photoelectric conversion part 2 by electrolyte solution can be prevented.
Although it will not specifically limit if the 2nd electrode 5 has electroconductivity, For example, it is a metal thin film, for example, is thin films, such as Al, Ag, Au. These can be formed by, for example, sputtering. Further, for example, a transparent conductive film such as In—Zn—O (IZO), In—Sn—O (ITO), ZnO—Al, Zn—Sn—O, and SnO ₂ is used.

6). Insulating part The insulating part 11 can be provided between the back surface of the photoelectric conversion part 2 and the second gas generating part 7. The insulating part 11 can also be provided between the first gas generating part 8 and the second gas generating part 7. Furthermore, the insulating part 11 is between the first conductive part 9 and the photoelectric conversion part 2, between the second conductive part 10 and the photoelectric conversion part 2, and between the second conductive part 10 and the second electrode 5. It can be provided in between.
By providing the insulating unit 11, an electromotive force generated in the photoelectric conversion unit 2 causes a current to flow between the light receiving surface of the photoelectric conversion unit 2 and the second gas generation unit 7. A current can flow between the gas generating unit 8 and the first gas generating unit 8. Further, the leakage current can be further reduced. Thus, the potential of the light receiving surface of the photoelectric conversion unit 2 and the potential of the second gas generation unit 7 can be made substantially the same, and the potential of the back surface of the photoelectric conversion unit 2 and the first gas generation unit 8 can be made. Can be made substantially the same, and hydrogen and oxygen can be generated more efficiently.
Moreover, it is preferable that the insulation part 11 has the corrosion resistance with respect to electrolyte solution, and the liquid shielding property with respect to electrolyte solution. Thereby, corrosion of the photoelectric conversion part 2 by electrolyte solution can be prevented.

The insulating part 11 can be used regardless of an organic material or an inorganic material. For example, polyamide, polyimide, polyarylene, aromatic vinyl compound, fluorine polymer, acrylic polymer, vinylamide polymer, etc. Examples of organic polymers and inorganic materials include metal oxides such as Al ₂ O ₃ , SiO ₂ such as porous silica films, fluorine-added silicon oxide films (FSG), SiOC, HSQ (Hydrogen Silsesquioxane) films, SiN _x , It is possible to use a method of forming a film by dissolving silanol (Si (OH) ₄ ) in a solvent such as alcohol and applying and heating.

  As a method for forming the insulating portion 11, a film containing a paste containing an insulating material is applied by a screen printing method, an ink jet method, a spin coating method, etc., dried or baked, or a CVD method using a source gas is used. And a method using a PVD method, a vapor deposition method, a sputtering method, a sol-gel method, and the like.

7). Second Conductive Part The second conductive part 10 can be provided so as to be in contact with the first electrode 4 and the second gas generating part 7, respectively. By providing the second conductive portion 10, the first electrode 4 that is in contact with the light receiving surface of the photoelectric conversion portion 2 and the second gas generating portion 7 can be easily electrically connected.
Since the second conductive unit 10 contacts the first electrode 4 in contact with the light receiving surface of the photoelectric conversion unit 2 and the second gas generation unit 7 provided on the back surface of the photoelectric conversion unit 2, the photoelectric conversion unit 2 If the cross-sectional area of the second conductive portion parallel to the light receiving surface is too large, the area of the light receiving surface of the photoelectric conversion portion 2 is reduced. Further, if the cross-sectional area of the second conductive part 10 parallel to the light receiving surface of the photoelectric conversion unit 2 is made too small, there is a difference between the potential of the light receiving surface of the photoelectric conversion unit 2 and the potential of the second gas generating unit 7. May occur, and a potential difference for decomposing the electrolytic solution may not be obtained, which may lead to a decrease in the generation efficiency of hydrogen or oxygen. Therefore, the cross-sectional area of the second conductive part parallel to the light receiving surface of the photoelectric conversion part 2 needs to be within a certain range. For example, the cross-sectional area of the second conductive part parallel to the light-receiving surface of the photoelectric conversion unit 2 (the total of the cross-sectional areas when there are a plurality of second conductive parts) is 100% of the area of the light-receiving surface of the photoelectric conversion unit 2 In this case, it can be 0.1% or more and 10% or less, preferably 0.5% or more and 8% or less, and more preferably 1% or more and 6% or less.

Further, the second conductive portion 10 may be provided in a contact hole that penetrates the photoelectric conversion portion 2. Thereby, the reduction in the area of the light receiving surface of the photoelectric conversion unit 2 due to the provision of the second conductive unit 10 can be further reduced. In addition, this makes it possible to shorten the current path between the light receiving surface of the photoelectric conversion unit 2 and the second gas generation unit 7 and to generate hydrogen or oxygen more efficiently. In addition, this makes it possible to easily adjust the cross-sectional area of the second conductive portion 10 parallel to the light receiving surface of the photoelectric conversion portion 2.
In addition, the contact hole provided with the second conductive portion 10 may be one or plural, and may have a circular cross section. The cross-sectional area of the contact hole parallel to the light-receiving surface of the photoelectric conversion unit 2 (the sum of the cross-sectional areas when there are a plurality of contact holes) is 0 when the area of the light-receiving surface of the photoelectric conversion unit 2 is 100%. .1% or more and 10% or less, preferably 0.5% or more and 8% or less, more preferably 1% or more and 6% or less. According to such a configuration, the reduction in the area of the light receiving surface of the photoelectric conversion unit due to the provision of the second conductive unit can be reduced.
Further, the second conductive portion 10 is formed from a portion provided in a contact hole penetrating the photoelectric conversion portion 2 and a portion provided between the second gas generating portion 7 and the insulating portion 11 as shown in FIG. It may be. As a result, the electrical connection between the second gas generation unit 7 and the second conductive unit 10 is sufficient, and the light receiving surface of the photoelectric conversion unit 2 and the potential of the second gas generation unit 7 are substantially the same. can do. In addition, a catalyst having low conductivity can be used for the second gas generation unit 7.
Further, the second conductive unit 10 may be provided in a region where the photoelectric conversion unit 2 is not formed.

  The material of the second conductive portion 10 is not particularly limited as long as it has conductivity. A paste containing conductive particles, for example, a carbon paste, an Ag paste or the like applied by screen printing, an inkjet method, etc., dried or baked, a method of forming a film by a CVD method using a raw material gas, a PVD method, Examples thereof include a vapor deposition method, a sputtering method, a sol-gel method, and a method using an electrochemical redox reaction.

  FIG. 5 shows a hydrogen production apparatus according to an embodiment of the present invention as viewed from the light receiving surface side. The cross section of the second conductive unit 10 parallel to the light receiving surface of the photoelectric conversion unit 2 may be circular as shown in FIG. 1 or may be elongated as shown in FIG. Further, the number of the second conductive parts 10 may be plural for each of the second gas generating parts 7 as shown in FIG. 1, and for each of the second gas generating parts 7 and 1 as shown in FIG. One may be sufficient. In addition, the second conductive portion 10 provided in the contact hole for electrically connecting the light receiving surface of the photoelectric conversion portion 2 and the second gas generating portion 7 has a long shape substantially parallel to the partition wall 13. May be formed. The second conductive portion 10 provided in the contact hole has a cross section parallel to the light receiving surface of the photoelectric conversion portion 2, and the cross section is a row of the first gas generation portion and the second gas generation portion. You may have a shape parallel to a direction.

8). First Gas Generation Unit The first gas generation unit 8 is provided on the back surface of the photoelectric conversion unit 2. Thus, the first gas generation unit 8 does not block the light incident on the photoelectric conversion unit 2. The first gas generation unit 8 is one of a hydrogen generation unit and an oxygen generation unit, and is electrically connected to the back surface of the photoelectric conversion unit 2. Thereby, the potential of the back surface of the photoelectric conversion unit 2 and the potential of the first gas generation unit 8 can be made substantially the same, and hydrogen or oxygen can be generated by the electromotive force generated in the photoelectric conversion unit 2. . Moreover, the 1st gas generation | occurrence | production part 8 is plural, and it may be provided so that it may be arranged in parallel with the 2nd gas generation | occurrence | production part 7 alternately. As a result, the boundary between the first gas generation unit 8 and the second gas generation unit 7 can be increased, and the electrolyte solution in the vicinity of the first gas generation unit 8 and the vicinity of the second gas generation unit 7 The distance of the electrolyte solution can be shortened. In addition, it is possible to facilitate the movement of protons in order to eliminate the proton concentration imbalance between the electrolyte near the first gas generator 8 and the electrolyte near the second gas generator 7. This can prevent a decrease in the hydrogen generation rate due to an imbalance of proton concentration.

Further, the first gas generation unit 8 can be provided so as not to contact the second gas generation unit 7. Thereby, it is possible to prevent leakage current from flowing between the first gas generation unit 8 and the second gas generation unit 7. Further, the first gas generation unit 8 may be exposed to the electrolyte flow path 15. As a result, H ₂ or O ₂ can be generated from the electrolytic solution on the surface of the first gas generating unit 8.

9. Second Gas Generating Unit The second gas generating unit 7 is provided on the back surface of the photoelectric conversion unit 2. Thus, the second gas generation unit 7 does not block the light incident on the photoelectric conversion unit 2. The second gas generation unit 7 is one of a hydrogen generation unit and an oxygen generation unit, and is electrically connected to the light receiving surface of the photoelectric conversion unit 2 via the first conductive unit 9. Thereby, the potential of the light receiving surface of the photoelectric conversion unit 2 and the potential of the second gas generation unit 7 can be made substantially the same, and hydrogen or oxygen can be generated by the electromotive force generated in the photoelectric conversion unit 2. it can. Moreover, the 2nd gas generation part 7 is plural, and it may be provided so that it may be arranged in parallel with the 1st gas generation part 8 alternately. As a result, the proton conduction path between the first gas generation unit 8 and the second gas generation unit 7 can be increased, and the decrease in the hydrogen generation rate due to the proton concentration imbalance can be prevented. it can. Further, the second gas generation unit 7 may be provided on the back surface of the photoelectric conversion unit 2 via the insulating unit 11. Further, the second gas generation unit 7 can be provided so as not to contact the first gas generation unit 8. This can prevent a leakage current from flowing. Further, the second gas generation unit 7 may be exposed to the electrolyte flow path 15. As a result, H ₂ or O ₂ can be generated from the electrolytic solution on the surface of the second gas generating unit 7.

  Further, the first gas generation unit 8 and the second gas generation unit 7 may be substantially rectangular or strip-shaped. The substantially rectangular or strip-shaped first gas generating section 8 and the substantially rectangular or strip-shaped second gas generating section 7 may be alternately arranged in parallel. Further, a partition wall 13 may be provided between the first gas generation unit 8 and the second gas generation unit 7. Furthermore, the first gas generation unit 8 and the second gas generation unit 7 may be provided such that the long sides are adjacent to each other with the partition wall 13 interposed therebetween.

Moreover, although the width | variety of the direction where the 1st gas generation part 8 and the 2nd gas generation part 7 were arranged in parallel is not specifically limited, For example, it may be the same and may differ like FIG. . The first gas generation unit 8 may have a width of, for example, 5 cm or more and 20 cm or less. The 2nd gas generation part 7 may have a width | variety of 5 cm or more and 20 cm or less, for example. According to such a configuration, even when the hydrogen production apparatus is enlarged, the distance that protons ion-conduct between the electrolyte near the first gas generator and the electrolyte near the second gas generator is reduced. Can be shortened. As a result, the proton concentration imbalance can be reduced, and a decrease in the hydrogen generation rate can be prevented.
Further, the width of the first gas generation unit 8 may be 50 or more and 200 or less, or 50 or more and 80 or less and 120 or more and 200 or less, where the width of the second gas generation unit 8 is 100. Also good. According to such a structure, the width | variety of the direction used as a hydrogen generation part can be made wider than the width | variety used as an oxygen generation part among a 1st gas generation part and a 2nd gas generation part, A decrease in the hydrogen generation rate due to the difference in the amount of oxygen generated can be prevented.

  Moreover, the width | variety of the direction used as a hydrogen generation part among the 1st gas generation part 8 and the 2nd gas generation part 7 may be wider than the width | variety used as an oxygen generation part. Further, the width of the hydrogen generation part may be 1.2 to 2.5 times the width of the oxygen generation part. In addition, the width of the first gas generation unit 8 and the second gas generation unit 7 that becomes the hydrogen generation unit can be substantially double the width of the direction that becomes the oxygen generation unit. Further, the width of the electrolyte channel 15 above the hydrogen generator and the width of the electrolyte channel 15 above the oxygen generator may be substantially 2: 1 in accordance with this width. Since the ratio of hydrogen and oxygen generation amount from water is 2: 1, if the activity of the hydrogen generation catalyst contained in the hydrogen generation part and the oxygen generation catalyst contained in the oxygen generation part are equivalent and the catalyst loading is equivalent, According to this configuration, the influence on the hydrogen generation rate and the oxygen generation rate due to accumulation of bubbles and gas can be made substantially the same, and hydrogen can be generated more efficiently.

Moreover, it is preferable that at least one of the first gas generation unit 8 and the second gas generation unit 7 has a catalyst surface area larger than the area of the light receiving surface. According to such a configuration, hydrogen or oxygen can be generated more efficiently by the electromotive force generated in the photoelectric conversion unit.
Moreover, it is preferable that at least one of the first gas generation unit and the second gas generation unit is a porous conductor carrying a catalyst. According to such a configuration, the surface area of at least one of the first gas generation unit and the second gas generation unit can be increased, and oxygen or hydrogen can be generated more efficiently. In addition, by using a porous conductor, a change in potential due to a current flowing between the photoelectric conversion unit and the catalyst can be suppressed, and hydrogen or oxygen can be generated more efficiently.

10. Hydrogen generating part The hydrogen generating part is a part that generates H ₂ from the electrolytic solution, and is one of the first gas generating part 8 and the second gas generating part 7. In addition, since hydrogen generate | occur | produces from the electrolyte solution near a hydrogen generation part, it is thought that the proton concentration of this electrolyte solution decreases. This decrease in proton concentration is eliminated by the generation of proton conduction with the electrolyte near the oxygen generating portion.

Further, the hydrogen generation unit may include a catalyst for a reaction in which H ₂ is generated from the electrolytic solution. Thereby, the reaction rate of the reaction in which H ₂ is generated from the electrolytic solution can be increased. The hydrogen generation part may consist only of a catalyst for the reaction in which H ₂ is generated from the electrolytic solution, or this catalyst may be supported on a support. Further, the hydrogen generation unit may have a catalyst surface area larger than the area of the light receiving surface of the photoelectric conversion unit 2. Thereby, the reaction in which H ₂ is generated from the electrolytic solution can be set to a faster reaction rate. The hydrogen generation part may be a porous conductor carrying a catalyst. This can increase the catalyst surface area. In addition, a change in potential due to a current flowing between the light receiving surface or the back surface of the photoelectric conversion unit 2 and the catalyst included in the hydrogen generation unit can be suppressed. Moreover, when this hydrogen generating part is the first gas generating part 8, even if the second electrode is omitted, a change in potential due to current flowing between the back surface of the photoelectric conversion part 2 and the catalyst is suppressed. Can do. Furthermore, the hydrogen generation unit may include at least one of Pt, Ir, Ru, Pd, Rh, Au, Fe, Ni, and Se as a hydrogen generation catalyst. According to such a configuration, hydrogen can be generated at a higher reaction rate by the electromotive force generated in the photoelectric conversion unit.

The catalyst for the reaction of generating H ₂ from the electrolyte (hydrogen generation catalyst) is a catalyst that promotes the conversion of two protons and two electrons into one molecule of hydrogen, is chemically stable, and generates hydrogen overvoltage. Can be used. For example, platinum group metals such as Pt, Ir, Ru, Pd, Rh, and Au, which have catalytic activity for hydrogen, and alloys or compounds thereof, Fe, Ni, and Se that constitute the active center of hydrogenase that is a hydrogen-producing enzyme. An alloy or a compound, a combination thereof, or the like can be preferably used. Among them, a nanostructure containing Pt and Pt has a small hydrogen generation overvoltage and can be suitably used. Materials such as CdS, CdSe, ZnS, and ZrO ₂ whose hydrogen generation reaction is confirmed by light irradiation can also be used.

  Although it is possible to directly support the hydrogen generating catalyst on the back surface of the photoelectric conversion unit 2, the catalyst can be supported on a conductor in order to increase the reaction area and improve the gas generation rate. Examples of the conductor carrying the catalyst include metal materials, carbonaceous materials, and conductive inorganic materials.

  As the metal material, a material having electronic conductivity and resistance to corrosion in an acidic atmosphere is preferable. Specifically, noble metals such as Au, Pt, Pd, metals such as Ti, Ta, W, Nb, Ni, Al, Cr, Ag, Cu, Zn, Su, Si, and nitrides and carbides of these metals, Examples of the alloy include stainless steel, Cu—Cr, Ni—Cr, and Ti—Pt. It is more preferable that the metal material contains at least one element selected from the group consisting of Pt, Ti, Au, Ag, Cu, Ni, and W from the viewpoint that there are few other chemical side reactions. These metal materials have a relatively small electric resistance, and can suppress a decrease in voltage even when a current is extracted in the surface direction. Further, when using a metal material having poor corrosion resistance in an acidic atmosphere such as Cu, Ag, Zn, etc., noble metals and metals having corrosion resistance such as Au, Pt, Pd, carbon, graphite, glassy carbon, A metal surface having poor corrosion resistance may be coated with a conductive polymer, a conductive nitride, a conductive carbide, a conductive oxide, or the like.

  As the carbonaceous material, a chemically stable and conductive material is preferable. Examples thereof include carbon powders and carbon fibers such as acetylene black, vulcan, ketjen black, furnace black, VGCF, carbon nanotube, carbon nanohorn, and fullerene.

Examples of the inorganic material having conductivity include In—Zn—O (IZO), In—Sn—O (ITO), ZnO—Al, Zn—Sn—O, SnO ₂ , and antimony oxide-doped tin oxide. .

  In addition, examples of the conductive polymer include polyacetylene, polythiophene, polyaniline, polypyrrole, polyparaphenylene, polyparaphenylene vinylene, and the like, and examples of the conductive nitride include carbon nitride, silicon nitride, gallium nitride, indium nitride, and nitride. Germanium, titanium nitride, zirconium nitride, thallium nitride, etc. are listed, and conductive carbides include tantalum carbide, silicon carbide, zirconium carbide, titanium carbide, molybdenum carbide, niobium carbide, iron carbide, nickel carbide, hafnium carbide, tungsten carbide. , Vanadium carbide, chromium carbide, and the like. Examples of the conductive oxide include tin oxide, indium tin oxide (ITO), and antimony oxide-doped tin oxide.

  The structure of the conductor supporting the hydrogen generation catalyst includes a plate shape, a foil shape, a rod shape, a mesh shape, a lath plate shape, a porous plate shape, a porous rod shape, a woven fabric shape, a nonwoven fabric shape, a fiber shape, and a felt shape. It can be used suitably. Further, a grooved conductor in which the surface of the felt-like electrode is pressure-bonded in a groove shape is preferable because the electric resistance and the flow resistance of the electrode liquid can be reduced.

11. Oxygen generating part The oxygen generating part is a part for generating O ₂ from the electrolytic solution, and is either one of the first gas generating part 8 and the second gas generating part 7. In addition, since oxygen generate | occur | produces from the electrolyte solution near an oxygen generation part, it is thought that the proton concentration of this electrolyte solution increases. This increase in proton concentration is eliminated by the generation of proton conduction with the electrolyte near the hydrogen generation part.

Further, the oxygen generation unit may include a catalyst for a reaction in which O ₂ is generated from the electrolytic solution. Thereby, the reaction rate of the reaction in which O ₂ is generated from the electrolytic solution can be increased. Further, the oxygen generation part may consist only of a catalyst for the reaction that generates O ₂ from the electrolytic solution, or the catalyst may be supported on a carrier. Further, the oxygen generation unit may have a catalyst surface area larger than the area of the light receiving surface of the photoelectric conversion unit 2. Thereby, the reaction in which O ₂ is generated from the electrolytic solution can be set to a faster reaction rate. The oxygen generation part may be a porous conductor carrying a catalyst. This can increase the catalyst surface area. In addition, a change in potential due to a current flowing between the light receiving surface or the back surface of the photoelectric conversion unit 2 and the catalyst included in the oxygen generation unit can be suppressed. Moreover, when this hydrogen generating part is the first gas generating part 8, even if the second electrode is omitted, the change in potential due to current flowing between the back surface of the photoelectric conversion part 2 and the catalyst is reduced. Can do. Furthermore, the oxygen generation unit may include at least one of Mn, Ca, Zn, Co, and Ir as an oxygen generation catalyst. According to such a configuration, oxygen can be generated at a higher reaction rate by the electromotive force generated in the photoelectric conversion unit.

The catalyst for the reaction of generating O ₂ from the electrolyte (oxygen generating catalyst) is a catalyst that promotes the conversion of two water molecules into one molecule of oxygen, four protons, and four electrons, and is chemically stable. In addition, a material having a small oxygen generation overvoltage can be used. For example, oxides or compounds containing Mn, Ca, Zn, Co, which are active centers of Photosystem II, which is an enzyme that catalyzes the reaction of generating oxygen from water using light, and platinum such as Pt, RuO ₂ , IrO ₂ It is possible to use compounds containing group metals, oxides or compounds containing transition metals such as Ti, Zr, Nb, Ta, W, Ce, Fe, Ni, and combinations of the above materials. Among these, iridium oxide, manganese oxide, cobalt oxide, and cobalt phosphate can be suitably used because they have low overvoltage and high oxygen generation efficiency.

  Although the oxygen generating catalyst can be directly supported on the light receiving surface or the back surface of the photoelectric conversion unit 2, the catalyst can be supported on a conductor in order to increase the reaction area and improve the gas generation rate. Examples of the conductor carrying the catalyst include metal materials, carbonaceous materials, and conductive inorganic materials. These explanations apply as long as there is no contradiction in the explanation of the hydrogen generation catalyst described in “10. Hydrogen generation section”.

  When the catalytic activity of the hydrogen generating catalyst and the oxygen generating catalyst alone is small, a promoter can be used. Examples thereof include oxides or compounds of Ni, Cr, Rh, Mo, Co, and Se.

  The method for supporting the hydrogen generating catalyst and the oxygen generating catalyst can be applied directly to a conductor or semiconductor, PVD methods such as vacuum deposition, sputtering, and ion plating, dry coating methods such as CVD, The method can be appropriately changed depending on the material such as an analysis method. A conductive material can be appropriately supported between the photoelectric conversion unit and the catalyst. Also, when the catalytic activity for hydrogen generation and oxygen generation is not sufficient, the reaction surface area is increased by supporting it on porous materials such as metals and carbon, fibrous materials, nanoparticles, etc., and the hydrogen and oxygen generation rates are improved. It is possible to make it.

12 The top plate 14 can be provided on the first gas generation unit 8 and the second gas generation unit 7 so as to face the substrate 1. Moreover, the top plate 14 can be provided such that a space is provided between the first gas generation unit 8 and the second gas generation unit 7 and the top plate 14.

  In addition, the top plate 14 is a material that forms a flow path of an electrolytic solution and the like to confine the generated hydrogen and oxygen, and a highly confidential substance is required. It is not particularly limited whether it is transparent or opaque, but is preferably a transparent material from the viewpoint that hydrogen and oxygen are visible. The transparent top plate is not particularly limited, and examples thereof include a transparent rigid material such as quartz glass, Pyrex (registered trademark), and a synthetic quartz plate, a transparent resin plate, and a transparent resin film. Among them, it is preferable to use a glass material because it is a gas that is not chemically permeable and is chemically and physically stable.

13. Partition Wall The partition wall 13 can also be received so as to partition the first gas generation unit 8 and the second gas generation unit 7. Further, the partition wall 13 can be provided so as to partition the space between the first gas generation unit 8 and the top plate 14 and the space between the second gas generation unit 7 and the top plate 14. Thereby, it is possible to prevent the hydrogen and oxygen generated in the first gas generation unit 8 and the second gas generation unit 7 from being mixed, and to separate and recover the hydrogen and oxygen.
The partition wall 13 may include an ion exchanger. As a result, protons that are unbalanced by the electrolytic solution in the space between the first gas generating unit 8 and the top plate 14 and the electrolytic solution in the space between the second gas generating unit 7 and the top plate 14 are obtained. The concentration can be kept constant. That is, the proton concentration can be eliminated through the movement of ions through the partition walls 9.

  For example, the partition wall 13 may be provided so as to contact the top plate 14 as shown in FIG. 2, or may be provided so that a space remains between the top plate 14 and the partition wall 13 as shown in FIG. By providing as shown in FIG. 7, proton imbalance can be more easily eliminated. Further, the partition wall 13 may be provided with holes. This can more easily eliminate proton imbalance. Even if a space is provided between the top plate 14 and the partition wall 13, the hydrogen production apparatus is installed with the light receiving surface of the photoelectric conversion unit 2 facing upward, so that mixing of hydrogen and oxygen can be prevented. Moreover, mixing of hydrogen and oxygen can be prevented by providing a hole near the top plate 14 of the partition wall 13.

In FIG. 2, the electrolyte channel 15 between the first gas generator 8 and the top plate 14 and the electrolyte channel 15 between the second gas generator 7 and the top plate 14 are completely separated by the partition wall 13. However, if there is no obstacle to the ion movement between the electrolyte flow paths, the partition wall 13 can be installed to form a gas flow path as shown in FIG. In this case, as shown in FIG. 7, the partition wall 13 can be installed by a lower cost means such as a printing method so that the generated hydrogen and oxygen are not mixed. At this time, a portion where the substrate 1 and the top plate 14 are joined becomes the sealing material 16. In order to increase the stability of the structure, it is also possible to provide a part of the partition wall 9 in contact with the top plate 14.
The partition wall 9 may have a belt-like cross section parallel to the back surface of the photoelectric conversion unit 2, and the cross section may have a width of 1 cm or more and 5 cm or less. Moreover, you may have a width | variety of 1 cm or more and 3 cm or less. According to such a configuration, the generated hydrogen and oxygen can be recovered more efficiently, and the interval between the first gas generation unit and the second gas generation unit can be further shortened. The proton concentration imbalance can be further reduced.

The ratio of the hydrogen generation amount and the oxygen generation amount from the electrolytic solution is a 2: 1 molar ratio, and the gas generation amount differs between the first gas generation unit 8 and the second gas generation unit 7. For this reason, it is preferable that the partition wall 13 is made of a material that allows water to pass through in order to keep the water content in the apparatus constant. For the partition wall 13, for example, an inorganic film such as porous glass, porous zirconia, or porous alumina or an ion exchanger can be used.
As the ion exchanger, any ion exchanger known in the art can be used, and a proton conductive membrane, a cation exchange membrane, an anion exchange membrane, or the like can be used.

  The material of the proton conductive film is not particularly limited as long as it is a material having proton conductivity and electrical insulation, and a polymer film, an inorganic film, or a composite film can be used.

  Examples of the polymer membrane include Nafion (registered trademark) manufactured by DuPont, Aciplex (registered trademark) manufactured by Asahi Kasei Co., and Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., which are perfluorosulfonic acid electrolyte membranes. Examples thereof include membranes and hydrocarbon electrolyte membranes such as polystyrene sulfonic acid and sulfonated polyether ether ketone.

  Examples of the inorganic film include films made of phosphate glass, cesium hydrogen sulfate, polytungstophosphoric acid, ammonium polyphosphate, and the like. Examples of the composite membrane include a membrane made of a sulfonated polyimide polymer, a composite of an inorganic material such as tungstic acid and an organic material such as polyimide, and specifically, Gore Select membrane (registered trademark) or pores manufactured by Gore. Examples thereof include a filling electrolyte membrane. Furthermore, when used in a high temperature environment (for example, 100 ° C. or higher), sulfonated polyimide, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), sulfonated polybenzimidazole, phosphonated polybenzimidazole, sulfuric acid. Examples include cesium hydrogen and ammonium polyphosphate.

  The cation exchange membrane may be any solid polymer electrolyte that can move cations. Specifically, fluorine ion exchange membranes such as perfluorocarbon sulfonic acid membranes and perfluorocarbon carboxylic acid membranes, polybenzimidazole membranes impregnated with phosphoric acid, polystyrene sulfonic acid membranes, sulfonated styrene / vinylbenzene copolymers Examples include membranes.

When the anion transport number of the supporting electrolyte solution is high, it is preferable to use an anion exchange membrane. As the anion exchange membrane, a solid polymer electrolyte capable of transferring anions can be used. Specifically, a polyorthophenylenediamine film, a fluorine-based ion exchange film having an ammonium salt derivative group, a vinylbenzene polymer film having an ammonium salt derivative group, a film obtained by aminating a chloromethylstyrene / vinylbenzene copolymer, etc. Can be mentioned.
When hydrogen generation and oxygen generation are selectively performed by a hydrogen generation catalyst and an oxygen generation catalyst, respectively, and ion movement accompanying this occurs, it is not always necessary to arrange a member such as a special membrane for ion exchange. . For the purpose of only physically isolating the gas, it is possible to use an ultraviolet curable resin or a thermosetting resin described in a sealing material described later.

14 Sealing material The sealing material 16 is a material for bonding the substrate 1 and the top plate 14 and sealing the electrolyte flowing in the hydrogen production apparatus 23 and the hydrogen and oxygen generated in the hydrogen production apparatus 23. As the sealing material 16, for example, an ultraviolet curable adhesive, a thermosetting adhesive, or the like is preferably used, but the type thereof is not limited. The UV curable adhesive is a resin that undergoes polymerization upon irradiation with light having a wavelength of 200 to 400 nm and undergoes a curing reaction within a few seconds after light irradiation, and is divided into a radical polymerization type and a cationic polymerization type. Examples of the polymerization type resin include acrylates, unsaturated polyesters, and examples of the cationic polymerization type include epoxy, oxetane, and vinyl ether. Examples of the thermosetting polymer adhesive include organic resins such as phenol resin, epoxy resin, melamine resin, urea resin, and thermosetting polyimide. The thermosetting polymer adhesive is heated and polymerized in a state where pressure is applied at the time of thermocompression bonding, and then cooled to room temperature while being pressurized. I don't need it. In addition to the organic resin, a hybrid material having high adhesion to the glass substrate can be used. By using a hybrid material, mechanical properties such as elastic modulus and hardness are improved, and heat resistance and chemical resistance are dramatically improved. The hybrid material is composed of inorganic colloidal particles and an organic binder resin. For example, what is comprised from inorganic colloidal particles, such as a silica, and organic binder resin, such as an epoxy resin, a polyurethane acrylate resin, and a polyester acrylate resin, is mentioned.

  Here, the sealing material 16 is described, but the sealing material 16 is not limited as long as it has a function of bonding the substrate 1 and the top plate 14. Physically using a member such as a screw from the outside using a resin or metal gasket. In addition, it is possible to appropriately use a method of increasing the confidentiality by applying pressure.

15. Electrolyte Channel The electrolyte channel 15 can be a space between the first gas generator 8 and the top plate 14 and a space between the second gas generator 7 and the top plate 14. Further, the electrolyte channel 15 can be partitioned by the partition wall 13.
For example, a pump, a fan, heat, etc. that circulates the electrolyte in the electrolyte channel so that the generated hydrogen and oxygen bubbles are efficiently separated from the first gas generator 8 or the second gas generator 7. It is also possible to provide a simple device such as a convection generator.

16. The water supply port, the first gas discharge port, the second gas discharge port, the first gas discharge channel and the second gas discharge channel The water supply port 18 is formed by making an opening in a part of the sealing material 16 included in the hydrogen production device 23. Can be provided. The water supply port 18 is arranged for replenishing water decomposed into hydrogen and oxygen, and the arrangement location and shape thereof are particularly limited as long as water as a raw material is efficiently supplied to the hydrogen production apparatus. Although it is not a thing, it is preferable to install in the lower part of a hydrogen production apparatus from a viewpoint of fluidity | liquidity and the ease of supply.

  The first gas discharge port 20 and the second gas discharge port 19 make an opening in the sealing material 16 in the upper part of the hydrogen production device 23 when the hydrogen production device 23 is installed with the water supply port 18 facing downward. Can be provided. Further, the first gas discharge port 20 may be provided outside one short side of the first gas generation unit, and the second gas discharge port 19 is formed on one short side of the second gas generation unit. It may be provided outside. Moreover, the 1st gas exhaust port 20 and the 2nd gas exhaust port 19 can be provided in the 1st gas generation part 20 side and the 2nd gas generation part 19 side on both sides of the partition 13.

  Moreover, the 1st gas exhaust port 20 and the 2nd gas exhaust port 19 are plurality, and may be provided so that it may rank alternately. Further, as shown in FIG. 8, the plurality of first gas discharge ports 20 may be connected to one first gas discharge passage 25, and the plurality of second gas discharge ports 19 are connected to one second gas discharge passage. 26 may be conducted. As a result, the generated hydrogen can be more easily recovered and the convenience can be improved.

  Thus, by providing the water supply port 18, the first gas discharge port 20, the second gas discharge port 19, the first gas discharge channel 25, and the second gas discharge channel 26, the hydrogen production device 23 receives light from the photoelectric conversion unit 2. It can be installed so that the surface is inclined with respect to the horizontal plane with the water supply port 18 on the lower side and the first gas discharge port 20 and the second gas discharge port 19 on the upper side. By installing in this way, the electrolytic solution can be introduced into the hydrogen production device 23 from the water supply port 18 and the electrolytic solution flow path 15 can be filled with the electrolytic solution. In this state, by making light incident on the hydrogen production apparatus 23, hydrogen and oxygen can be continuously generated in the hydrogen generation unit and the oxygen generation unit, respectively. The generated hydrogen and oxygen can be separated by the partition wall 13, and the hydrogen and oxygen can rise to the upper part of the hydrogen production device 23 and can be recovered from the first gas discharge path 25 and the second gas discharge path 26. .

17. Electrolytic Solution The electrolytic solution is an aqueous solution containing an electrolyte, such as an electrolytic solution containing 0.1 M H ₂ SO ₄ , a 0.1 M potassium phosphate buffer solution, or the like.

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the examples.

1. Example 1
The following hydrogen production apparatus as shown in FIGS.
In the produced hydrogen production apparatus, the SnO ₂ thin film as the first electrode 4 is provided on the glass substrate as the substrate 1. A three-junction photoelectric conversion unit 2 composed of an a-Si layer is stacked on the first electrode 4, and a second electrode 5 of a transparent electrode layer composed of indium tin oxide (ITO) is further formed on the surface. Is provided. A hydrogen generation part (first gas generation part 8) carrying the hydrogen generation catalyst 4 is provided on the second electrode 5 while being isolated from the second electrode 5 by an insulating part 11 made of a polyimide film. In this form, an oxygen generating part (second gas generating part 7) carrying an oxygen generating catalyst is provided from the first electrode 4 through the second conductive part 10 made of Ag paste. A plurality of hydrogen generation units and oxygen generation units are arranged in parallel, and are sandwiched between the substrate 1 and the glass top plate 14 so as to have a structure in which the electrolyte flows on the layer where the hydrogen generation unit and the oxygen generation unit are provided. As described above, a structure in which an electrolytic solution flow path 15 that is a space for flowing an electrolytic solution is provided and a partition wall 13 made of a glass filter is provided between the hydrogen generating portion and the oxygen generating portion so that hydrogen and oxygen are not mixed is configured. Details of the manufacturing process will be described below.

As the substrate 1 and the first electrode 4, a glass substrate with U-type tin dioxide (SnO ₂ ) manufactured by Asahi Glass Co., Ltd. was used.
Next, an a-Si film was formed by plasma CVD. First, an a-SiO p layer having a thickness of 20 nm was formed at a substrate temperature of 150 ° C. using SiH ₄ and CO ₂ as main gases, B ₂ H ₆ as a doping gas, and hydrogen as a diluent gas. Thereafter, an a-Si i-layer having a film thickness of 200 nm using SiH ₄ as the main gas and H ₂ as the dilution gas, again with a film thickness of 10 nm using SiH ₄ and CO ₂ as the main gas, PH ₃ as the doping gas, and hydrogen as the dilution gas. N layers of a-SiO were sequentially formed to form a photoelectric conversion layer having a pin junction. Thereafter, two more photoelectric conversion layers having pin junctions were formed by the same method, and the photoelectric conversion unit 2 including three photoelectric conversion layers was formed. Subsequently, ITO having a film thickness of 200 nm was formed by a sputtering method. The formed photoelectric conversion part 2 and the second electrode 5 are a photolithography process, (1) a resist is applied on a silicon thin film, (2) light exposure is performed using a photomask, and a latent image of a mask pattern is formed on the resist. And (3) development to pattern the resist, the thin film was etched, and (4) resist stripping was performed to form a contact hole.

Next, in order to form the insulating part 11 for insulating the second conductive part 10 from the photoelectric conversion part 2 and the second electrode 5, a material is applied and baked by spin coating to produce a polyimide film. did. Subsequently, Ag paste was applied onto the substrate by screen printing, an iridium oxide sheet was placed thereon, and the second conductive portion 10 and the oxygen generation portion were formed in the contact hole by heat treatment. Further, Pt was formed on the second electrode 5 by sputtering to produce a hydrogen generating part.
A porous glass partition wall 9 is disposed between the hydrogen generation catalyst and the oxygen generation catalyst, and the substrate and the top plate, and the substrate / top plate and the partition wall are connected by using an acid-resistant epoxy resin sealing material 13. A hydrogen production apparatus according to the present invention was produced.

2. Example 2
A hydrogen production apparatus as shown in FIG. 5 was produced under the following conditions.
In the same manner as in Example 1, on the substrate 1, the photoelectric conversion unit 2, the second electrode 5, the insulating unit 11, the second conductive unit 10, the oxygen generation unit (second gas generation unit 7), and hydrogen generation Parts (first gas generation part 8) were formed. Here, the difference from the first embodiment is that the contact hole provided with the second conductive portion 10 is provided along the long axis direction of the second gas generating portion 7. Thus, by reducing the number of contact holes, it is possible to reduce contact failure, and also when the width of the second gas generator 7 is made narrower, the cross-sectional area of the contact holes is The contact formation by this structure can be made narrower than the width of the second gas generating part 7 connected to the two conductive parts 10, and hydrogen and oxygen can be produced efficiently.

3. Example 3
A hydrogen production apparatus as shown in FIG. 7 was produced under the following conditions.
In the same manner as in Example 1, on the substrate 1, the photoelectric conversion unit 2, the second electrode 5, the insulating unit 11, the second conductive unit 10, the oxygen generation unit (second gas generation unit 7), and hydrogen generation Parts (first gas generation part 8) were formed.
Subsequently, as shown in FIG. 7, the partition wall 13 is thermosetting so that the gas is efficiently collected at a location between the first gas generation unit 8 and the second gas generation unit 7. After the polyimide was produced by the screen printing method, the periphery of the device was sealed with a sealing material for the substrate side material and the top plate material. In this way, a hydrogen production apparatus was produced.

4). Example 4
A hydrogen production apparatus as shown in FIG. 6 was produced under the following conditions.
In the same manner as in Example 1, on the substrate 1, the photoelectric conversion unit 2, the second electrode 5, the insulating unit 11, the second conductive unit 10, the oxygen generation unit (second gas generation unit 7), and hydrogen generation Parts (first gas generation part 8) were formed. Here, the difference from the first embodiment is that the widths of the first gas generation unit 8 and the second gas generation unit 7 are different. When one molecule of water is electrolyzed, hydrogen is generated at a ratio of 1 molecule and oxygen is generated at a ratio of 0.5 molecule. Therefore, it is possible to change the width of the catalyst layer according to the catalyst activity and the amount of supported catalyst to achieve a balance. It was.

5. Example 5
In the hydrogen production apparatus produced in Example 1, the oxygen generation unit was produced as follows.
PH 7 and 0.1M potassium phosphate buffer and 0.5mM cobalt nitrate on the cathode side of a glass electrochemical cell with a glass filter as a partition, and pH 7 and 0.1M potassium phosphate buffer on the anode side. I put it in. Porous carbon is immersed in the cathode electrolyte, Pt mesh is immersed in the anode electrolyte, the electrodes are electrically connected, and then a phosphoric acid is electrochemically applied by applying a potential of 1.29 V (vs NHE). Cobalt was supported on porous carbon. By forming the oxygen generation catalyst thus prepared in the second gas generation unit 7 of the hydrogen production apparatus of Example 1, it is possible to manufacture an apparatus having a larger surface area and an improved oxygen generation rate. became.

6). Example 6
The hydrogen production apparatus produced in Example 1 was installed obliquely so that sunlight was incident in a direction perpendicular to the light receiving surface. An electrolyte containing 0.1 M H ₂ SO ₄ was injected from the water supply port 18 to the vicinity of the first gas outlet 20 and the second gas outlet 19 and irradiated with sunlight. It is confirmed by gas chromatography that hydrogen and oxygen are generated from the gas generator 8 and the second gas generator 7, respectively, and that hydrogen is discharged from the first gas outlet 20 and oxygen is discharged from the first gas outlet 20. did.

7). Example 7
A hydrogen production apparatus in which the oxygen generation catalyst produced in Example 5 was formed in the second gas generation unit 7 was installed obliquely so that sunlight was incident in a direction perpendicular to the light receiving surface. When the electrolyte surface containing the pH 7, 0.1M potassium phosphate buffer solution was injected from the water supply port 18 to the vicinity of the first gas discharge port 20 and the second gas discharge port 19 and irradiated with sunlight, The gas chromatography indicates that hydrogen and oxygen are generated from the first gas generation unit 8 and the second gas generation unit 7 respectively, and that hydrogen is discharged from the first gas discharge port 20 and oxygen is discharged from the first gas discharge port 20. Confirmed. As a result, it was confirmed that hydrogen could be produced using a neutral electrolyte.

  The hydrogen production apparatus of the present invention is utilized as an energy creation apparatus that decomposes water by using solar energy to produce hydrogen and oxygen. Hydrogen can be produced on-site at home, hydrogen stations, and large-scale hydrogen production plants.

1: Substrate 2: Photoelectric conversion unit 4: First electrode 5: Second electrode 7: Second gas generation unit 8: First gas generation unit 9: First conductive unit 10: Second conductive unit 11: Insulating part 13: Partition 14: Top plate 15: Electrolyte flow path 16: Sealing material 18: Water supply port 19: Second gas discharge port 20: First gas discharge port 23: Hydrogen production device 25: First gas discharge channel 26 : Second gas discharge passage

Claims (21)

A photoelectric conversion unit having a light receiving surface and a back surface, and a first gas generation unit and a second gas generation unit provided in parallel on the back surface,
Of the first gas generation unit and the second gas generation unit, one is a hydrogen generation unit that generates H ₂ from the electrolytic solution, and the other is an oxygen generation unit that generates O ₂ from the electrolytic solution,
At least one of the first gas generator and the second gas generator is plural,
The first gas generation unit is electrically connected to the back surface, and the second gas generation unit is electrically connected to the light receiving surface via a first conductive unit.   The apparatus according to claim 1, wherein the first gas generation unit and the second gas generation unit are provided so as to be alternately arranged.   The apparatus according to claim 1, further comprising a partition wall between the first gas generation unit and the second gas generation unit.   The said partition is an apparatus of Claim 3 provided so that the 1st gas generation part and the 2nd gas generation part may be partitioned off.   5. The apparatus according to claim 3, wherein the first gas generation unit and the second gas generation unit are substantially rectangular and are provided so that long sides are adjacent to each other with the partition wall interposed therebetween. A first gas discharge port provided on the outer side of one short side of the first gas generating unit;
A second gas discharge port provided on the outer side of one short side of the second gas generation unit,
The apparatus according to claim 5, wherein the first gas outlet and the second gas outlet are provided side by side. The first gas outlet and the second gas outlet are plural,
The plurality of first gas discharge ports are connected to one first gas discharge path,
The apparatus according to claim 6, wherein the plurality of second gas discharge ports are connected to one second gas discharge path.   The apparatus according to claim 3, wherein the partition wall includes an ion exchanger.   The device according to claim 1, wherein the second gas generation unit is provided on the back surface via an insulating unit.   The apparatus according to claim 9, further comprising a second electrode provided between the back surface and the first gas generation unit.   The device according to claim 10, wherein the second electrode and the insulating portion have corrosion resistance and liquid shielding properties against the electrolytic solution.   The first conductive portion includes a first electrode in contact with the light receiving surface, and a second conductive portion in contact with the first electrode and the second gas generation unit, respectively. The device described in 1.   The device according to claim 12, wherein the second conductive portion is provided in a contact hole that penetrates the photoelectric conversion portion. The second conductive portion has a cross section parallel to the light receiving surface,
The apparatus according to claim 13, wherein the cross section has an elongated shape parallel to a row direction of the first gas generation unit and the second gas generation unit.   The said photoelectric conversion part is an apparatus as described in any one of Claims 1-14 provided on the board | substrate which has translucency.   The device according to claim 1, wherein the photoelectric conversion unit includes a photoelectric conversion layer including a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer. The hydrogen generation part and the oxygen generation part respectively include a catalyst for a reaction in which H ₂ is generated from the electrolytic solution and a catalyst for a reaction in which O ₂ is generated from the electrolytic solution. apparatus.   The apparatus according to claim 17, wherein at least one of the hydrogen generator and the oxygen generator is a porous conductor carrying a catalyst. The photoelectric conversion unit is provided on a substrate having translucency,
A top plate facing the substrate is further provided on the first gas generation unit and the second gas generation unit, and a space is provided between the first gas generation unit and the second gas generation unit and the top plate. 19. Apparatus according to any one of the preceding claims, provided. A partition is further provided between the first gas generation unit and the second gas generation unit,
The said partition is an apparatus of Claim 19 provided so that the space between a 1st gas generation part and the said top plate and the space between a 2nd gas generation part and a top plate may be partitioned off. The hydrogen production apparatus according to any one of claims 1 to 20, wherein the light receiving surface is inclined with respect to a horizontal plane,
An electrolyte is introduced into the hydrogen production apparatus from a lower part of the hydrogen production apparatus, and sunlight and light are incident on the light receiving surface to generate hydrogen and oxygen from the hydrogen generation part and the oxygen generation part, respectively. A method for producing hydrogen in which hydrogen and oxygen are discharged from the upper part of the apparatus.

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