WO2005063393A1

WO2005063393A1 - Method for electrolyzing water using organic photocatalyst

Info

Publication number: WO2005063393A1
Application number: PCT/JP2004/018886
Authority: WO
Inventors: Keiji Nagai; Toshiyuki Abe
Original assignee: Kansai Technology Licensing Organization Co., Ltd.; Tmt Machinery, Inc.
Priority date: 2003-12-26
Filing date: 2004-12-17
Publication date: 2005-07-14
Also published as: JP3995051B2; TW200534330A; JPWO2005063393A1

Abstract

Disclosed is a method for efficiently producing hydrogen and oxygen by electrolyzing water with light irradiation using an organic photocatalyst which is capable of effectively utilizing all the light in the visible range. The present invention relates to an organic photocatalyst containing a p-type organic semiconductor and an n-type organic semiconductor, an electrode material for electrolysis of water which is composed of such an organic photocatalyst, an electrode covered with such an electrode material, a method for electrolyzing water using such an electrode, an apparatus for electrolyzing water and the like.

Description

Specification

Water electrolysis method using organic photocatalyst

Technical field

The present invention relates to a method for efficiently electrolyzing water into hydrogen and oxygen under light irradiation using an organic photocatalyst activated by light, particularly visible light, as an electrode material.

Background art

[0002] The use of light to decompose water molecules into hydrogen and oxygen has attracted much attention as a potential solar energy conversion / storage system, in particular, decomposing water under visible light irradiation. The development of photocatalysts that can be used has been a big topic in recent years.

[0003] Further, performing hydrogen generation without generating carbon dioxide is a necessary technology for building a hydrogen-cycle energy society that replaces the carbon cycle.

[0004] A conventional alkaline water electrolyzer has been put to practical use under conditions requiring a high applied voltage of 1.7 to 2.0 V at a high temperature of about 60 to 80 ° C or higher (see Non-Patent Document 1). . In other words, electrolysis of water requires the addition of excess thermal energy and an additional overvoltage of approximately 0.5-0.8 V with respect to the theoretical voltage of 1.23 V.

[0005] However, there is much room for improvement in terms of effective use of energy and electrolysis of water under mild conditions. In addition, in ordinary water electrolysis, the driving power, electricity, is generated while emitting a large amount of carbon dioxide, which poses problems from the viewpoints of energy efficiency, environmental destruction, global warming, etc. ing.

[0006] In order to solve these problems, attempts have been made to actively use natural energy (for example, light energy). For example, Non-Patent Document 2 reports a water decomposition reaction by an inorganic semiconductor photocatalyst using light energy.

[0007] However, the photocatalyst is only a few types of titanium oxide, composites thereof, tungsten oxide, and the like that can utilize ultraviolet light or near-ultraviolet visible light (Non-Patent Document 3 and the like), and covers the entire visible light region. There is no known photocatalyst capable of utilizing light over a wide range.

[0008] In addition, most of the photocatalysts used so far for the decomposition reaction of water are inorganic photocatalysts, and organic photocatalysts, in particular, can generate both hydrogen and oxygen, and have an electrical component of water. There has been no report of an organic photocatalyst that can be used in water that is indispensable for the solution (Non-Patent Document 4).

[0009] Further, a photooxidation catalyst of water in which a water oxidation catalyst such as a metal complex is combined with a sensitizer has been studied, but the catalytic activity under light irradiation is remarkably low, and the light energy efficiency is low. It was far from useful (see Patent Document 1).

[0010] Further, Non-Patent Document 5 describes a single-layer electrode using an organic semiconductor such as anthracene. However, a sufficient photocurrent has not been obtained, and the performance of this organic material cannot be improved. It is stated that it is impossible to build a good photovoltaic cell and use it to extract chemical energy.

Patent Document 1: JP-A-9-234374

Non-Patent Document 1: Electrochemistry and Industrial Physical Chemistry April, p278-282, 2003

Non-Patent Document 2: Nature, 414, pp. 625-627 (2001)

Non-Patent Document 3: Chem. Commun., 150 (1992)

Non-Patent Document 4: J. Chem. Soc. Faraday Trans., 93, 221 (1997)

Non-Patent Document 5: Review of Chemistry No.45 Functional Organic Thin Film Published November 25, 1984

Disclosure of the invention

Problems to be solved by the invention

[0011] In view of the above-described problems of the conventional technology, the present invention provides an electrode material using an organic photocatalyst capable of utilizing light in the ultraviolet and visible regions, and electrolyzes water under light irradiation to form hydrogen and hydrogen. It is a main object to provide a method for efficiently producing oxygen.

Means for solving the problem

[0012] The present inventors have conducted intensive studies to achieve the above object, and as a result, irradiated an organic photocatalyst comprising a specific p-type organic semiconductor and a specific n-type organic semiconductor with ultraviolet light or visible light. Then, they found that a photocatalytic oxidation-reduction reaction occurs through unidirectional photo-induced electron transfer. Further, when electrolysis of water was performed using an electrode using the organic photocatalyst as an electrode material under irradiation of ultraviolet light or visible light, it was found that electrolysis was possible under milder conditions. The present inventors have further developed the present invention based on these findings.

Specifically, the present invention provides the following organic photocatalyst, electrode material for electrolysis of water, and the electrode material And an electrolysis method for water using the electrode, a water electrolysis apparatus, and the like.

Item 1. An electrode material for water electrolysis comprising an organic photocatalyst containing a p-type organic semiconductor and an n-type organic semiconductor.

Item 2. The electrode material for electrolysis of water according to Item 1, wherein the p-type organic semiconductor is a macrocyclic ligand compound or a metal complex thereof.

Item 3. The electrode material for electrolysis of water according to Item 1 or 2, wherein the p-type organic semiconductor is at least one member selected from the group consisting of a phthalocyanine derivative, a naphthalocyanine derivative, and a porphyrin derivative.

Item 4. The electrode material for electrolysis of water according to Item 1, 2 or 3, wherein the n-type organic semiconductor is a polycyclic aromatic compound.

Item 5. The item in which the n-type organic semiconductor is at least one selected from the group consisting of fullerenes, carbon nanotubes, a conductive polymer doped with an electron donor, a perylene derivative, and a naphthalene derivative. 14. The electrode material for electrolysis of water according to any one of items 1-4.

Item 6. An electrode in which the surface of an electrode substrate is coated with the electrode material for water electrolysis according to any one of Items 115.

[0020] Item 7. The electrode according to item 6, wherein the surface of the electrode substrate is coated with a first layer made of an n-type organic semiconductor and a second layer made of a p-type organic semiconductor. An anode electrode that supports a transition metal catalyst on the second layer, if necessary.

[0021] Item 8. The electrode according to item 6, wherein the surface of the electrode substrate is coated with a first layer made of a p-type organic semiconductor and a second layer made of an n-type organic semiconductor. A force sword electrode that supports a transition metal catalyst on the second layer, if necessary.

Item 9. The electrode according to item 6, wherein the electrode substrate is a conductive transparent glass substrate, a metal substrate, or a carbon-based substrate.

Item 10. An electrolysis apparatus for water comprising: an anode electrode according to item 7, an electrode serving as a force source electrode according to item 8, a constant potential power supply, an aqueous electrolyte solution, and a light source.

Item 11. The item according to Item 10, wherein the anode electrode and the force source electrode are connected to a constant potential power supply, and the anode electrode and the force source electrode are immersed in an aqueous electrolyte solution. Water electrolysis equipment.

[0025] Item 12. The water electrolysis apparatus according to Item 11, wherein a voltage is applied to the anode electrode and the force source electrode with a constant potential power supply while irradiating the electrodes with light. Disassembly method.

Item 13. The water electrolysis method according to item 12, wherein the applied voltage is about 0.3 to 1.2 V.

Item 14. An electrode comprising the anode electrode and the force source electrode according to Item 7, or an electrode comprising the force electrode and the anode electrode according to Item 8, a constant potential power source, an aqueous electrolyte solution, and a light source. Water electrolysis equipment.

Item 15. The water electrolysis apparatus according to item 14, wherein the anode electrode and the force source electrode are connected to a constant potential power supply, and the anode electrode and the force source electrode are immersed in an aqueous electrolyte solution.

[0029] Item 16. The water electrolysis apparatus according to Item 15, wherein a voltage is applied to the anode electrode and the force source electrode with a constant potential power supply while irradiating the electrodes with light. Disassembly method.

Item 17. The water electrolysis method according to Item 16, wherein the applied voltage is about 1.0 to 1.4 V.

Item 18. The method for electrolyzing water according to Item 12 or 16, wherein the irradiation light is natural light.

Item 19. The water electrolysis method according to Item 12 or 16, wherein oxygen is generated from the anode electrode and hydrogen is generated from the force source electrode.

Item 20. An organic photocatalyst containing a p-type organic semiconductor and an n-type organic semiconductor.

Item 21. The organic photocatalyst according to item 20, wherein the p-type organic semiconductor is a macrocyclic ligand compound or a metal complex thereof.

Item 22. The organic photocatalyst according to item 20, wherein the p-type organic semiconductor is at least one member selected from the group consisting of a phthalocyanine derivative, a naphthalocyanine derivative, and a porphyrin derivative.

Item 23. The organic photocatalyst according to item 20, wherein the n-type organic semiconductor is a polycyclic aromatic compound.

Item 24. Item 20 wherein the n-type organic semiconductor is at least one selected from the group consisting of fullerenes, carbon nanotubes, a conductive polymer doped with an electron donor, a perylene derivative, and a naphthalene derivative. The organic photocatalyst according to the above. Hereinafter, the present invention will be described in detail.

I. ^ m

The organic photocatalyst of the present invention contains a p-type organic semiconductor and an n-type organic semiconductor, and is preferably used as an electrode material for water electrolysis described later because it is stable in a medium containing water. Can be

_[0038] Ό ¾ί body

P-type organic semiconductors include macrocyclic ligand compounds or metal complexes thereof. The macrocyclic ligand compound means a cyclic compound that can be a ligand of a metal containing an atom having an unpaired electron on the ring, and the metal complex is a metal complex with the macrocyclic ligand. It means a metal complex consisting of metal atoms. Examples of the atom having an unpaired electron include a nitrogen atom and an oxygen atom, and a nitrogen atom is preferable. Examples of the metal atom include metal elements belonging to groups 11 to 15 of the periodic table, preferably metal elements belonging to groups 4 to 14. The metal complex is usually a metal complex composed of the metal atom and the macrocyclic ligand compound in a molar ratio of 1: 1 to form a four-coordinate planar complex.

[0039] Specific examples of the macrocyclic ligand compound or its metal complex include a phthalocyanine derivative, a naphthalocyanine derivative, and a porphyrin derivative.

[0040] The phthalocyanine derivative means a compound having a basic skeleton of phthalocyanine.

Specifically, for example, the following formula (1A) or (1B):

[0041] [Formula 1]

(In the formula, M ¹ represents a metal atom selected from the group consisting of Groups 414 of the Periodic Table or an atomic group containing the metal atom, and a dotted line represents a coordination bond.) A phthalocyanine derivative represented by

[0043] Preferably one of the periodic table 4 one 14 metal atom represented by M ^1, Group 4 (especially, Ή), Group 5 (in particular, V), Group 6 (in particular, Mo), 7 group ( In particular, Mn), Group 8 (Fe, Ru, Os), Group 9 (Co, Rh, Ir), Group 10 (Ni, Pd, Pt), Group 11 (particularly Cu), Group 12 (particularly Zn) , Group 13 (particularly Al) and Group 14 (particularly Pb). Further, the atomic group containing the metal atom means a group in which another ligand (eg, oxygen or cyano group) is coordinated with the metal (for example, Ti-〇).

[0044] Among the above, in the phthalocyanine represented by the formula (1A) or in the formula (1B), M ¹ is Co, Pt,

Phthalocyanine derivatives which are Os, Mn, Ir, Fe, Rh, Cu, Zn, Ni, Pd or Ru are preferred, and cobalt phthalocyanine is particularly preferred in terms of the amount of oxygen generated in the electrolysis of water. All of these compounds are commercially available or can be easily produced by those skilled in the art.

[0045] The naphthalocyanine derivative means a compound having a basic skeleton of naphthalocyanine. Specifically, for example, the following formula (2A) or (2B):

[0046]

(In the formula, M ² represents a metal atom selected from the group consisting of Groups 414 of the Periodic Table or an atomic group containing the metal atom, and a dotted line represents a coordination bond.)

And a naphthalocyanine derivative represented by

[0048] Preferably one of the periodic table 4 one 14 metal atom shown by M ^2, Group 4 (especially, Ή), Group 5 (in particular, V), Group 6 (in particular, Mo), 7 group ( In particular, Mn), Group 8 (Fe, Ru, Os), Group 9 (Co, Rh, Ir), Group 10 (Ni, Pd, Pt), Group 11 (particularly Cu), Group 12 (particularly Zn) , Group 13 (especially Al), group 14 (especially Pb ). Further, the atomic group containing the metal atom means one in which another ligand (for example, oxygen or cyano group) is coordinated to the metal (for example, Ti-O).

[0049] Among the above, in the naphthalocyanine represented by the formula (2A) or in the formula (2B), M ² is Co, Pt,

Naphthalocyanine derivatives which are 〇s, Mn, Ir, Fe, Rh, Cu, Zn, Ni, Pd or Ru are preferred, and cobalt naphthalocyanine is particularly preferred in terms of the amount of oxygen generated in the electrolysis of water. These compounds are all commercially available or can be easily prepared by those skilled in the art.

[0050] The porphyrin derivative means a compound having a basic skeleton of porphyrin. Specifically, for example, the following formula (3A) or (3B):

[0051] [Formula 3]

(Wherein, R ³ represents a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group, and M ³ contains a metal atom selected from the group consisting of Groups 4 to 14 of the periodic table or a metal atom thereof (Indicates atomic groups, dotted lines indicate coordination bonds.)

And a porphyrin derivative represented by

[0053] Here, the alkyl group represented by R ³ above is a C straight-chain or branched-chain alkyl.

1 20

And is preferably an alkyl group of c. Specifically, Mechinore, Ethil

1 10

, N-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, n-pentyl, n-hexyl, n-heptyl, n-octyl and the like.

Examples of the aryl group represented by R ³ include a monocyclic or bicyclic aryl group, and specific examples include phenyl and naphthyl.

[0055] Further, as the Heteroariru group represented by the above R ^3, pyridyl, Birajiniru etc. ani I can get lost.

[0056] Preferably one of the periodic table 4 one 14 metal atom represented by M ^3, Group 4 (especially, Ή), Group 5 (in particular, V), Group 6 (in particular, Mo), 7 group ( In particular, Mn), Group 8 (Fe, Ru, Os), Group 9 (Co, Rh, Ir), Group 10 (Ni, Pd, Pt), Group 11 (particularly Cu), Group 12 (particularly Zn) , Group 13 (particularly Al) and Group 14 (particularly Pb). Further, the atomic group containing the metal atom means a group in which another ligand (eg, oxygen or cyano group) is coordinated with the metal (for example, Ti-〇).

[0057] Among the above, a porphyrin of the formula (3A), or M ³ in the formula (3B) Co, Pt, Os , Mn, Ir, Fe, Rh, Cu, Zn, Ni, Pd or Ru, Porphyrin derivatives in which R ³ is phenyl or a hydrogen atom are preferred, and cobalt porphyrin is particularly preferred in view of the amount of oxygen generated in the electrolysis of water. These compounds are all commercially available or can be easily produced by those skilled in the art.

[0058] n-type organic semiconductor

The n-type organic semiconductor includes a polycyclic aromatic compound (which may be partially saturated). A polycyclic aromatic compound is a compound having a structure in which at least two or more aromatic rings are fused, or a structure in which multiple aromatic rings are bonded via an unsaturated bond (double bond, triple bond, etc.). And the like. The aromatic ring includes, in addition to the benzene ring and the like, a heteroaromatic ring such as a pyrrole ring, an imidazole ring, a pyridine ring and a quinoxaline ring. ,).

[0059] The polycyclic aromatic compound may have various substituents as long as the compound does not adversely affect the present invention. Examples of the substituent include an electron withdrawing group, and specific examples include a carbonyl group, a sulfone group, and a sulfoxide group.

[0060] Specific examples of the polycyclic aromatic compound include fullerenes such as C60, C70, C76, C82, and C84; carbon nanotubes; and electron donors (phenylenediamine, tetraaminoethylene, tris (2, Conductive polymers (polyimide, polyphenylenevinylene, polyparaphenylene, polypyrrole, etc.) doped with 2-biviridine) ruthenium; perylene derivatives; naphthalene derivatives. Among them, perylene derivatives, naphthalene derivatives, fullerenes (C60 and the like) and the like are preferably employed, and perylene derivatives and fullerenes (C60 and the like) are particularly preferable.

[0061] The perylene derivative means a compound having a basic skeleton of perylene. In particular For example, the following formula (4A)-(4C):

[0062] [Formula 4]

(4C)

(Wherein, R ¹ represents an alkyl group or an aryl group)

And a perylene derivative represented by

[0064] The naphthalene derivative means a compound having a basic skeleton of naphthalene. Specifically, for example, the following formula (5A):

[0065]

(5Α)

(Wherein, R ² represents an alkyl group or an aryl group)

The naphthalene derivative represented by these is mentioned.

Here, the alkyl group represented by R ¹ or R ² above is a C straight-chain or branched-chain And an alkyl group of C 2 is preferable. Specifically, methyl

1-10

, Ethyl, n-propyl, isopropyl, sec-butyl, isobutyl, n-pentyl, n-hexyl, n-heptyl, n-octyl and the like.

[0068] Further, as the Ariru group represented by R ¹ or R ^2, include Ariru group mono- or bicyclic, in particular phenyl, naphthyl and the like.

[0069] In the organic photocatalyst of the present invention, there is no particular limitation on the form of bonding between the p-type organic semiconductor and the n-type organic semiconductor, but it is preferable to bond them so that the contact area between them increases. For example, a film-shaped p-type organic semiconductor and an n-type organic semiconductor may be joined, or one of the organic semiconductor films may be coated with the other organic semiconductor component to have a layer (film) structure.

II.Electric angle of water ¾

In the water electrolysis method of the present invention, water is efficiently converted into hydrogen and oxygen by applying a voltage while irradiating light to an electrode coated with an organic photocatalyst comprising a p-type organic semiconductor and an n-type organic semiconductor. It is characterized by electrolysis. A schematic diagram is shown in FIG.

[0070] fi

The electrode used in the electrolysis of water of the present invention has an electrode substrate surface coated with an organic photocatalyst.

[0071] Examples of the electrode substrate include a conductive transparent glass substrate, a metal substrate, and a carbon-based substrate. Specifically, for example, a conductive transparent glass base material coated with indium tin oxide (ITO) or the like; a metal base material such as platinum; a carbon base material such as graphite, diamond, glassy carbon or the like can be used. The resistance value of the electrode substrate is, for example, 5-100 Ω m ² , preferably 820 Ω m ² . In addition, it is preferable that the shape of the electrode substrate be a variety of shapes. A force that can be used.

[0072] The organic photocatalyst covering the electrode substrate is composed of a specific p-type organic semiconductor and a specific n-type organic semiconductor.

[0073] As the p-type organic semiconductor used for the electrode of the present invention, a p-type organic semiconductor having a high activity as an oxygen generation catalyst capable of efficiently generating oxygen in the electrolysis of water during light irradiation is used. It is. Examples of the p-type organic semiconductor include the above-described macrocyclic ligand compounds and metal complexes thereof, and preferably include phthalocyanine derivatives, naphthalocyanine derivatives, and porphyrin derivatives. More preferably, compounds represented by the formulas (1A), (IB) ヽ (2A), (2B), (3A), and (3B) are preferable. Particularly, a metal complex of phthalocyanine (cobalt phthalocyanine) in which M ¹ is represented by Co in the formula (1B) is preferable. The above-mentioned p-type organic semiconductor is available as a commercial product or can be easily manufactured by those skilled in the art.

[0074] The n-type organic semiconductor used for the electrode of the present invention can generate hydrogen efficiently in the electrolysis of water during light irradiation, and has a favorable relationship with the p-type organic semiconductor. Those having a pn junction relationship are used. Examples of the n-type organic semiconductor include the above-mentioned polycyclic aromatic compounds (which may be partially saturated), and preferably include perylene derivatives, naphthalene derivatives, and fullerenes. More preferably, compounds represented by formulas (4A), (4B), (4C), and (5A) are preferable. In particular, from the viewpoint of efficient carrier generation, perylene derivatives (3,4,9,10-perylenetetracarboxyl-bisbenzimidazole) or fullerenes (C60 and the like) represented by the formula (4A) are preferably used. . The above-mentioned n-type organic semiconductor is available as a commercial product or can be easily manufactured by those skilled in the art.

[0075] The electrode of the present invention is formed by coating an electrode substrate with an organic photocatalyst obtained by combining the n-type organic semiconductor and the p-type organic semiconductor. The specific configuration of the electrode is as follows.

The anode (anode) has a first layer (film) made of an n-type organic semiconductor on the surface of an electrode substrate, and has a second layer (film) made of a p-type organic semiconductor thereon. ing. The first layer is a continuous film having a thickness of usually about 200 to 800 nm (preferably about 250 to 650 nm) covering the electrode, and the second layer is usually about 20 to 500 nm (preferably 30 to 350 nm) covering the electrode. )). Regarding the thickness of the organic semiconductor layer, if the layer is too thick, the absorption efficiency of visible light decreases due to its own filter effect. Therefore, the first layer is more preferably about 250 to 650 nm, and the second layer is more preferably about 30 350 nm.

[0077] In addition to the first layer (film) made of an n-type organic semiconductor and the second layer (film) made of a P-type organic semiconductor on the surface of the above-mentioned electrode substrate, a second layer Transition metal on A catalyst (eg, a Ni, Pd, Pt, Ir catalyst or the like, preferably a Pt or Ir catalyst) may be supported. The transition metal catalyst supported on the second layer does not need to completely cover the second layer and may be dispersed and supported. For example, the transition metal catalyst is supported on the second layer in the form of fine particles having an average particle size of about 5 to 800 nm (preferably about 10 100 nm).

[0078] The anode electrode employing such a configuration becomes an efficient oxygen generating electrode. At the anode, electrons excited by light (especially visible light) flow through the n-type organic semiconductor toward the electrode substrate, and holes generated by photoexcitation flow through the p-type organic semiconductor toward the electrolyte. . At the interface between the P-type organic semiconductor and the electrolyte, water (or hydroxide ions) is oxidized by holes to generate oxygen (see, for example, Figure 1).

Until now, in the electrolysis of water by irradiation of light (visible light) using a photocatalyst, the amount of generated oxygen was extremely low. However, according to the electrolysis method using the electrode of the present invention, oxygen is efficiently used. Can be generated. This point can be easily understood, for example, from the description of the examples.

Further, even when compared with the photooxidation catalyst of water described in Patent Document 1 (Japanese Patent Application Laid-Open No. 9-234374) described in the background art, the amount of oxygen generated per unit catalyst amount (oxygen generation efficiency) Has increased significantly.

On the other hand, the force source electrode (cathode) has a first layer (film) made of a p-type organic semiconductor on the surface of an electrode substrate, and a second layer (film) made of an n-type organic semiconductor thereon. have. The first layer is a continuous film having a thickness of usually about 20 to 500 nm (preferably about 30 to 350 nm) covering the electrode, and the second layer is generally about 200 to 800 nm (about 200 to 800 nm) covering the first layer. It preferably consists of a continuous film having a thickness of about 250 to 650. Regarding the thickness of the organic semiconductor layer, if the layer is too thick, the absorption efficiency of visible light decreases due to its own filter effect. Therefore, the first layer is more preferably about 30 to 350 nm, and the second layer is more preferably about 250 650 nm.

[0082] Further, in addition to the first layer (film) made of a p-type organic semiconductor and the second layer (film) made of an n-type organic semiconductor, a force source electrode A transition metal catalyst (eg, a Ni, Pd, Pt, Ir catalyst or the like, preferably a Pt or Ir catalyst) supported on the layer may be used. The transition metal catalyst supported on the second layer does not need to completely cover the second layer and may be dispersed and supported. For example, a transition metal catalyst has an average particle size of 5800 nm. Particles (preferably about 10-100 nm) are supported on the second layer.

[0083] The cathode electrode employing such a configuration becomes an efficient hydrogen generating electrode. In a force source electrode, electrons excited by light (especially visible light) flow in the n-type organic semiconductor toward the electrolyte, and holes generated by photoexcitation flow in the p-type organic semiconductor toward the electrode substrate. . At the interface between the n-type organic semiconductor and the electrolyte, water (or protons) receives electrons and is reduced to generate hydrogen (see, for example, Figure 1).

[0084] As a method of coating each electrode substrate with an n-type organic semiconductor and a p-type organic semiconductor, known methods can be adopted, for example, vacuum deposition, sputtering, electrochemical coating (electrodeposition). ) And coating from a solution. Above all, with respect to the perylene derivative Z phthalocyanine derivative system, a vacuum deposition method is preferable because a uniform coating film can be obtained. It is preferable that the thickness of each organic semiconductor covering each electrode is appropriately set in the above-described range.

[0085] Specifically, the anode electrode forms an n-type organic semiconductor layer (first layer) by vacuum-depositing an n-type organic semiconductor on a conductive transparent glass substrate, and forms a p-type organic semiconductor thereon. The P-type organic semiconductor layer (second layer) may be formed by vacuum evaporation. On the other hand, the force source electrode is formed by vacuum-depositing a P-type organic semiconductor on a conductive transparent glass substrate to form a P-type organic semiconductor layer (first layer), and then vacuum-depositing an n-type organic semiconductor thereon. The organic semiconductor layer (second layer) may be formed.

[0086] Further, when a transition metal catalyst is supported on the second layer of each electrode, a known method such as an electroanalysis method (electrochemical reduction) can be employed. For example, with respect to platinum loading, a method of adding platinum salts such as KPtCl, KPtCl, and HPPtCl to an aqueous solution containing sulfuric acid, phosphoric acid, or the like, and loading platinum under a force source condition may be mentioned. As the applied force sword condition, it is preferable that the applied voltage is about 0-0.2 V (vs. Ag / AgCl). The concentration of the acid is usually about ImMlOmM, and the concentration of the platinum salt is preferably about O.lmM ImM.

[0087] An electrode coated with force, and thus with the organic photocatalyst of the present invention, is produced. By using the electrode of the present invention, water (especially light in the entire visible wavelength range) can be used to electrolyze water at a cell voltage lower than the theoretical voltage, and hydrogen and oxygen can be efficiently used. Can be generated It becomes possible. Moreover, the electrode using the organic photocatalyst of the present invention has a feature that the electrode itself is stable without being decomposed by oxidation or the like even under the condition of electrolysis of water.

[0088] In the electrolysis of water of the present invention, a force source electrode and / or an anode electrode containing the above-mentioned organic photocatalyst are used.

For example, (a) a force source electrode having a first layer made of a p-type organic semiconductor and a second layer made of an n-type organic semiconductor on the surface of an electrode substrate, and an n-type organic semiconductor A combination of an anode electrode having a first layer comprising a P-type organic semiconductor and a second layer comprising a P-type organic semiconductor; (b) a first layer comprising a P-type organic semiconductor and a second layer comprising an n-type organic semiconductor on the surface of the electrode substrate A combination of a force source electrode having a transition metal catalyst and an anode electrode having a first layer made of an n-type organic semiconductor and a second layer made of a p-type organic semiconductor on the surface of the electrode substrate, (c) an electrode substrate Force electrode having a first layer made of a p-type organic semiconductor and a second layer made of an n-type organic semiconductor on the surface of the electrode, and a first layer made of an n-type organic semiconductor and a p-type organic semiconductor on the surface of the electrode substrate A combination of a second layer and an anode electrode having a transition metal catalyst, (d) an electrode base A first layer made of a p-type organic semiconductor on the surface of the material, a second layer made of an n-type organic semiconductor, and a force electrode having a transition metal catalyst; a first layer made of an n-type organic semiconductor on the surface of the electrode substrate; and a combination of a second layer made of a p-type organic semiconductor and an anode electrode having a transition metal catalyst.

Further, in the electrolysis of water of the present invention, a combination of the above-mentioned force electrode or anode electrode containing an organic photocatalyst and an anode or force electrode consisting of a known electrode (such as a platinum electrode) is used. It may be. That is, one of the electrodes may be an electrode containing the organic photocatalyst of the present invention, and the other may be a known electrode.

[0091] In this case, since only one of the electrodes composed of the organic photocatalyst uses light, the efficiency of use of solar energy is reduced. The electric decomposition of water is sufficiently possible with a cell voltage smaller than the theoretical voltage. Yes, hydrogen and oxygen can be generated efficiently.

[0092] Thunder solution 7k liquid

As the aqueous electrolyte solution used in the electrolysis of the present invention, an acidic aqueous solution or an alkaline aqueous solution is suitably used.

[0093] The acidic aqueous solution is preferably an aqueous solution containing an acid such as phosphoric acid or sulfuric acid. Especially preferred Alternatively, it is a phosphoric acid aqueous solution. The concentration of the acid in the aqueous solution may usually be about 1 mM to 1 M. For example, when an electrode coated with the above-mentioned fullerenes / phthalocyanine derivative is used, the pH of the acid aqueous solution is preferably about 113.

[0094] Examples of the alkaline aqueous solution include an aqueous solution of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, which contains an electrolyte such as a phosphate, a sulfate, a nitrate, a carbonate, or an acetate. preferable. Particularly preferred is an aqueous solution of an alkali metal hydroxide. The concentration of the alkali metal hydroxide in the aqueous solution may usually be about 1 mM 1 M. For example, when an electrode coated with the above perylene derivative Z phthalocyanine derivative is used, the pH of an aqueous alkali metal hydroxide solution is preferably about 10-11.

[0095] ()

The light used in the present invention can use light having a wide range of wavelengths (wavelength of about 220 to 800 nm). The light source is selected from, for example, natural light (sunlight), fluorescent lamp, halogen lamp, high-pressure mercury lamp, low-pressure mercury lamp, black light, excimer laser, deuterium lamp, xenon lamp, Hg-Zn-Pb lamp, etc. Different types of light sources or two types of light sources having different wavelength ranges can be used. In particular, the present invention is extremely practical in that natural light can be used for electrolysis over almost the entire wavelength range (wavelength 300-800ηm) due to the nature of the organic photocatalyst comprising an n-type organic semiconductor and a p-type organic semiconductor. .

[0096] In the electrolysis of water of the present invention, the light source may be usually irradiated with light from the light source to an anode electrode containing an organic photocatalyst and / or a force sword electrode containing an organic photocatalyst. When a known electrode (such as a platinum electrode) is used for any one of the electrodes, the electrode containing the organic photocatalyst may be irradiated.

[0097] Lightning source and applied voltage

In the electrolysis of water of the present invention, an anode electrode containing an organic photocatalyst and a force sword electrode containing an organic photocatalyst were used, and when light was applied to both electrodes, the applied voltage of the power source was 0.3 to 1.2 V A low voltage (preferably about 0.8 1. IV) is sufficient. This is because the present invention employs an electrode using an organic photocatalyst as described above, so that a light-induced voltage is generated by light irradiation, and a power supply having a lower voltage than the theoretical voltage can be used. is there. In other words, by effectively using light energy, the power consumption for electrolysis can be increased. The ability to reduce S can.

When an electrode containing an organic photocatalyst is used for one electrode, a known electrode (eg, a platinum electrode) is used for the other electrode, and the electrode containing the organic photocatalyst is irradiated with light, the applied voltage of the power supply is At a low voltage of about 1.0 1.4V (preferably about 1.1 to 1.3V). Also in this case, by using light energy at the electrode including the organic photocatalyst, the applied voltage can be reduced and the power consumption used for the electrolysis can be significantly reduced.

[0099] By employing the method for decomposing water of the present invention, it is possible to effectively utilize solar energy and to generate oxygen and hydrogen safely and efficiently. Further, the electrolysis of water of the present invention can be carried out at normal temperature (for example, about 0.degree. C.), which is advantageous in that heating and pressurization are not required. The generated hydrogen can be used effectively for fuel cell fuels and existing hydrogen utilization technologies (eg, petroleum refining, petrochemical manufacturing, metallurgy, etc.).

in- 7k electrolysis equipment

The water electrolysis apparatus of the present invention includes the above-described anode electrode, force electrode, power supply (constant potential power supply), electrolyte aqueous solution, and light source (for example, see FIG. 1). The anode electrode and the force source electrode are connected to a power supply for applying a voltage, and each electrode is partially or entirely immersed in an aqueous electrolyte solution. As a specific electrolyzer, an electrolyzer having a single-chamber bipolar cell is exemplified.

[0100] As the anode electrode and the force sword electrode, those described above are used. As the aqueous electrolyte solution, those described above are used. For example, in the case of an electrode coated with a fullerene / phthalocyanine derivative, the pH is preferably about 113, and in the case of an electrode coated with a perylene derivative / phthalocyanine derivative, the pH is preferably about 10-11.

[0101] Note that, depending on the properties of the electrode containing the organic photocatalyst, the pH of the electrolyte solution in which the anode electrode and the force electrode are immersed may be different. In that case, a reaction cell with a salt bridge separating the electrolyte solution of the anode electrode and the force electrode is used. For example, the embodiment of Example 6 is exemplified. Specifically, in the electrolyte solution, the reaction tank on the anode electrode (anode) side is alkali water adjusted to pH-11 with sodium hydroxide or potassium hydroxide, and the reaction on the power source electrode (cathode) side. Acidified tank adjusted to pH-2 with phosphoric acid or sulfuric acid There is a bipolar cell that uses water and connects both tanks with a salt bridge.

[0102] The light source described above is used, but it is preferable to use natural light from the viewpoint of effective use of natural energy.

The invention's effect

[0103] According to the water electrolysis method of the present invention, an organic photocatalyst capable of utilizing light in the ultraviolet and visible regions is used as an electrode material, and water is efficiently converted into hydrogen and oxygen under mild conditions under light irradiation. The angle of separation can be S.

[0104] That is, the present invention provides a method for electrolysis of clean water (including hydrogen ions and hydroxide ions) that can effectively utilize natural energy (solar energy) and reduce carbon dioxide emissions. .

[0105] Conventional alkaline water electrolyzers have been put to practical use under conditions of high temperature (about 60-80 ° C or higher) and application of a voltage of 1.7-2.0 V (theoretical voltage is 1.23 V). Furthermore, the use of an electrode equipped with the organic photocatalyst of the present invention eliminates the need for the input of thermal energy required for the stoichiometric production of hydrogen and oxygen. Water can be electrolyzed even at a cell voltage lower than the voltage, which can greatly reduce the consumption of electric energy.

Brief Description of Drawings

FIG. 1 is a schematic view of a method for electrolyzing water using an organic photocatalyst of the present invention.

FIG. 2 is a schematic diagram of a photoelectrochemical measurement device according to Examples 1 and 2 and Comparative Example 1.

FIG. 3 is a schematic diagram of a photoelectrochemical measurement device according to Examples 3 and 4 and Comparative Examples 2 and 3.

FIG. 4 is a schematic diagram of a photoelectrochemical measurement device according to Example 5.

FIG. 5 is a schematic diagram of a photoelectrochemical measurement device according to Example 6.

FIG. 6 is a schematic diagram of a photoelectrochemical measurement device according to Example 7.

BEST MODE FOR CARRYING OUT THE INVENTION

[0107] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 (Oxygen-causing vortex at irradiation of halogen lamp) Electrode substrate / PV / CoPc is used as photoanode (working electrode), platinum wire as counter electrode, silver / silver chloride electrode as reference electrode, and alkaline water adjusted to pH-11 with sodium hydroxide or potassium hydroxide. Thus, a three-electrode cell as shown in FIG. 2 was constructed. When electrolysis was carried out under the halogen lamp irradiation at an applied potential of +0.3 V, oxygen was generated at about 3-4 μ1 / h. The specific operation procedure is shown below.

[0109] (1) As organic photocatalyst materials, n-type semiconductor 3,4,9,10-perylenetetracarboxynor-bisbenzimidazole (hereinafter referred to as "PV") and p-type semiconductor cobalt lid Mouth cyanine (hereinafter referred to as “CoPc”) was used. In the present invention, sublimated products were used.

(2) The production of the organic photocatalytic device was performed by a vacuum evaporation method. First, a conductive transparent glass substrate (hereinafter referred to as “ITO-coated glass substrate”) coated with indium monotin oxide (ITO) (manufactured by Nippon Sheet Glass Co., Ltd., resistance 13 Ωcm- ² ; transmittance of glass 85%; The PV was laminated with a thickness of 250 to 650 nm on the indium tin oxide laminate thickness of 110 nm, and then the CoPc was laminated with a thickness of 30 to 350 nm on the PV.

(3) The organic photocatalyst device prepared in the above (2) was cut into lcm × 1.5 cm. Lcm of which

A portion corresponding to X 0.5 cm was wiped off with acetone, and a conductive wire was attached using a silver-containing epoxy adhesive (T-700, manufactured by Toyo Ink Manufacturing Co., Ltd.). In order to prevent contact between the silver part and water, the electrode was insulated with an epoxy adhesive to form an organic photocatalyst-coated electrode.

[0112] (4) The photocatalytic reaction cell was produced by the following method. Using the organic photocatalyst-coated electrode prepared in (3) above as the working electrode, a platinum wire as the counter electrode, and a silver / silver chloride electrode (the internal solution is a saturated aqueous solution of potassium chloride) as a reference electrode, constructing a one-chamber type three-electrode cell. did. As the electrolyte solution, alkaline water adjusted to pH 11 with sodium hydroxide or potassium hydroxide was used.

(5) The organic photocatalytic reaction was carried out using a measuring device as shown in FIG. Function generator

(Hokuto Denko, HB-104), Coulomb meter (Hokuto Denko, HF-201) and XY recorder (Graphtec, WX-4000) equipped with a potentiometer / galvanostat (Hokuto Denko, HA-301), and a halogen lamp (150 W) was used as a light source.

[0114] (6) At normal temperature and normal pressure, a photoanode current accompanying oxidation of hydroxide ions was obtained in a potential region more noble than about +0.2 V (vs. Ag / AgCl). Actually, constant potential electrolysis is performed at +0.3 V, The product was analyzed by gas chromatography (GC-8A, manufactured by Shimadzu Corporation), and it was confirmed that about 3-4 μ1 / h- ¹ of oxygen was generated.

[0115] 2 OH— → 1/20 + H 0 + 2e

twenty two

Example 2 (light, cattle in fr s temple.

Electrode substrate / PV / CoPc using photoanode (working electrode), platinum wire as counter electrode, silver / silver chloride electrode as reference electrode, and alkaline water adjusted to pH 11 with sodium hydroxide or potassium hydroxide Thus, a three-electrode cell as shown in FIG. 2 was constructed. When electrolysis was performed under an applied potential of +0.4 V under natural light irradiation, about 1.5 uL / h of oxygen and about 3.5 μ1 / h of hydrogen were generated. The specific operation procedure is shown below.

(1) As an organic photocatalyst material, PV as an n-type semiconductor and CoPc as a p-type semiconductor were used. In the present invention, those purified by sublimation were used.

(2) The production of the organic photocatalytic device was performed by a vacuum deposition method. First, ITO coated glass substrate

(Nippon Sheet Glass Co., Ltd., resistance 13 Ωcm- ² ; transmittance of glass 85%; laminated thickness of indium tin oxide 110 nm), PV is 250-300 nm thick, then CoPc on PV Was laminated at a thickness of 135-145 nm.

[0119] (4) The photocatalytic reaction cell was produced by the following method. Using the organic photocatalyst-coated electrode prepared in (3) above as the working electrode, a platinum wire as the counter electrode, and a silver / silver chloride electrode (the internal solution is a saturated aqueous solution of potassium chloride) as a reference electrode, constructing a one-chamber type three-electrode cell. did. As the electrolyte solution, alkaline water adjusted to pH-11 with sodium hydroxide or potassium hydroxide was used.

(Hokuto Denko, HB-104), Coulomb meter (Hokuto Denko, HF-201) and XY recorder (Graphtec, WX-4000) equipped with a potentiometer / galvanostat (Hokuto Denko, HA-301) was used. Natural light was used as the light source.

[0121] (6) Light using natural light for a total of 3 hours from 11 am to 2 pm on a clear summer day An experiment on electrochemical water decomposition was performed. The minimum light quantity at this time is 58 mW

The maximum light intensity was 64 mW cm- ² , and the average light intensity was about 62 mW cm- ² .

[0122] (7) Photochemical water decomposition under natural light irradiation was performed under a condition in which a bias potential of +0.4 V was applied at a water temperature of about 36 ° C under normal pressure. As a result of analyzing the reaction product by gas chromatography (GC-8A, manufactured by Shimadzu Corporation), as an oxidation product (at the organic photocatalyst electrode (photoanode)), oxygen was approximately 1.5 μ1 h— (platinum counter electrode (force sword)). It was confirmed that hydrogen was generated as a reduction product in (about 3.5 μl h).

[0123] Comparative Example 1 (Oxygen-causing vortex range in darkness (reference data))

In connection with Examples 1 and 2, an electrode supporting a working oxygen generating catalyst was prepared, and electrocatalytic oxygen in alkaline water adjusted to pH-11 with sodium hydroxide or potassium hydroxide was used. Occurred. As the oxygen generating catalyst, Ir〇, whose high catalytic activity is known, was used. The specific operation procedure is shown below.

(1) About 2.5 mg of IrO (manufactured by Aldrich) was coated on a glass substrate (1 X lcm ² ) (manufactured by Nippon Sheet Glass Co., Ltd., resistance: 13 Ωcm— ² ; transmittance of glass: 85%; indium Coating was carried out on a stack thickness of soxide (110 nm). To suppress the peeling of the coated IrO, 15 μl of an alcohol solution of 0.05 wt.% Naphion (registered trademark of DuPont) was applied and air-dried at room temperature. Using.

(2) An oxygen generation experiment was performed without using a light source using the reaction cell and the measurement device shown in FIG. 2, and a voltage of about +1.0 V (vs. Ag / AgCl) was obtained on the IrO electrode. An anodic current based on oxygen evolution was obtained in a wide potential range. Actually, a constant potential electrolysis was performed at +1.2 V, and the product was analyzed with a gas chromatograph (Shimadzu Corporation, GC-8A) as in Example 1 (6).

Oxygen generation of 5-6 μ 1 / h- ¹ was confirmed.

[0126] From Examples 1 and 2 and Comparative Example 1, in Examples 1 and 2 employing an anode electrode containing an organic photocatalyst, a photoanode current was generated by irradiation with natural light or visible light, and the level was lower than that in Comparative Example 1. It was confirmed that oxygen was generated at a (low) applied potential.

Example 3 (Hydrogen-causing vortex at irradiation with halogen lamp)

(1) PV as an n-type semiconductor and phthalocyanine as a p-type semiconductor (hereinafter referred to as “H Pc”) were used as organic photocatalyst materials. In the present invention, each sublimation purified Was used.

(Nippon Sheet Glass Co., Ltd., resistance: 10 Ωcm- ² )

2

One 650 nm thick, laminated on HPc. Further, platinum black fine particles were supported.

2

[0130] (4) The photocatalytic reaction cell was produced by the following method. Using the organic photocatalyst-coated electrode prepared in (3) above as the working electrode, a platinum wire as the counter electrode, and a silver / silver chloride electrode (the internal solution is a saturated aqueous solution of potassium chloride) as a reference electrode, constructing a one-chamber type three-electrode cell. did. As the electrolyte solution, alkaline water adjusted to pH 11 with sodium hydroxide or potassium hydroxide was used.

[0132] (6) At room temperature and under normal pressure, in the potential region lower than about -0.7 V (vs. Ag / AgCl), a light source current accompanying hydrogen generation was obtained. The product was analyzed with a gas chromatograph (GC-8A, manufactured by Shimadzu Corporation) to confirm the generation of hydrogen.

[0133] 2 H 0 + 2 → 20H— + H

twenty two

Comparative Example 2 (Hydrogen evolution vortex in the dark (reference data))

In connection with Example 3, an electrode supporting a hydrogen generating catalyst that works for a long time was produced, and hydrogen was generated in alkaline water adjusted to pH-11 with sodium hydroxide or potassium hydroxide. Platinum black, which is known to have high activity, was used as the hydrogen generation catalyst. The specific operation procedure is shown below.

(1) 10 ml of a K PtCl aqueous solution containing about 0.3 g was prepared, and about 50 mg of lead acetate was added thereto.

2 4 2

Pyrolytic graphite (basal plane) under the condition of about 50-100 mAcm- ² using PtCl aqueous solution

Four

pyrolytic graphite) The electrode (about 0.2cm ² ) is subjected to force sword polarization, and about 3-4 coulombs (C) are energized to become white. A gold black electrode was obtained. After washing this platinum black electrode with water, it was used for a hydrogen generation experiment.

(2) A hydrogen generation experiment was carried out using the reaction cell and the measuring device (without using a light source) shown in FIG. 3, and a voltage of about -0.9 V (vs. Ag / A force sword current based on hydrogen evolution was obtained in a potential region lower than AgCl). Actually, constant potential electrolysis was performed at -1.0 V, and the product was analyzed by gas chromatography (GC-8A, manufactured by Shimadzu Corporation) in the same manner as in Example 1 (6). ¹ hydrogen generation was confirmed. Also, when a polycrystalline platinum plate (lcm ² ) was used, hydrogen was obtained in the same manner.

[0136] 2 H〇 + 2e— → H + 2 OH—

From Example 3 and Comparative Example 2 described above, in Example 3 employing a force sword electrode containing an organic photocatalyst, a light power sword electrode was generated by irradiation with visible light, which was higher than Comparative Example 2 at a (noble) applied potential. Generation of hydrogen was confirmed.

Example 4 (Hydrogen-causing vortex at irradiation with halogen lamp)

(1) As an organic photocatalyst material, C as an n-type semiconductor and H Pc as a p-type semiconductor were used. In the present invention, those purified by sublimation were used.

(Asahi Glass Co., Ltd., resistance 8 Ωcm- ² ; transmittance of glass 85%; laminated thickness of indium tin oxide 174 nm) on top of 30-350 nm thickness of H Pc and then 100-200 nm thickness of C Now, it was laminated on HPc. Further, platinum black fine particles were supported.

(4) The photocatalytic reaction cell was produced by the following method. Using the organic photocatalyst-coated electrode prepared in (3) above as the working electrode, a platinum wire as the counter electrode, and a silver / silver chloride electrode (the internal solution is a saturated aqueous solution of potassium chloride) as a reference electrode, constructing a one-chamber type three-electrode cell. did. As an electrolyte solution, acidic water adjusted to pH 2 with phosphoric acid or sulfuric acid was used.

(Hokuto Denko, HB-104), Coulomb meter (Hokuto Denko, HF-201) and XY recorder A potentiometer / galvanostat (Hokuto Denko, HA-301) equipped with a loader (WX-4000, manufactured by Graphtec) was used, and a halogen lamp (150 W) was used as a light source.

[0142] (6) At room temperature and under normal pressure, a photovoltaic sword current accompanying hydrogen generation was obtained in a potential region lower than about +0.1 V (vs. Ag / AgCl). Actually, constant-potential electrolysis was performed at -0.1 V, and the product was analyzed by gas chromatography (GC-8A, manufactured by Shimadzu Corporation). As a result, hydrogen generation of about 10 15 μ 1 / h- ¹ was confirmed.

[0143] 2H ⁺ + 2e— → H

2

Comparative Example 3 (Hydrogen cattle vortex in darkness (reference data))

In connection with Example 4, an electrode supporting a hydrogen generating catalyst that works for a long time was prepared, and hydrogen was generated in acidic water adjusted to pH-2 with phosphoric acid or sulfuric acid. Platinum black, which is known to have high activity, was used as the hydrogen generation catalyst. The specific operation procedure is shown below.

[0144] (1) 10 ml of a K PtCl aqueous solution containing about 0.3 g was prepared, and about 50 mg of lead acetate was added thereto.

2 4 2

To repeat the potential operation in the range of +0.4 V-0.1 V (vs. Ag / AgCl) using PtCl aqueous solution

Four

ITO-coated glass substrate by law (manufactured by Asahi Glass Company, resistance 8 Omega cm- ^2; transmittance of 85 percent glass; Injiu Musuzuokishido laminate thickness 174 nm) of the electrode (about lcm ²⁾ to force cathode polarization, about 0.01 0.05 Coo Ron (C) was energized to obtain a platinum black electrode. After washing this platinum black electrode with water, it was used for a hydrogen generation experiment.

[2] (2) A hydrogen generation experiment was performed using the reaction cell and the measuring device (without using a light source) shown in FIG. 3, and a voltage of about -0.3 V (vs. Ag / A force sword current based on hydrogen evolution was obtained in a potential region lower than AgCl). Actually, constant potential electrolysis was performed at -0.4 V, and the product was analyzed by gas chromatography (GC-8A, manufactured by Shimadzu Corporation) in the same manner as in Example 1 (6). ¹ hydrogen generation was confirmed. Also, when a polycrystalline platinum plate (lcm ² ) was used, hydrogen was obtained in the same manner.

[0146] 2H + + 2e— → H

2

From Example 4 and Comparative Example 3 described above, in Example 4 employing a force sword electrode containing an organic photocatalyst, a light power sword current was generated by irradiation with visible light, and hydrogen was applied at a higher (noble) applied potential than Comparative Example 3. Occurrence was confirmed.

[0147] Example 5 (Existence of n solution using n hornworm shrinkage) Electrode substrate / PV / CoPc photo-anode electrode (anode), Electrode substrate / H Pc / PV / Platinum catalyst light

2

A bipolar cell as shown in Fig. 4 was constructed using alkaline water adjusted to pH-11 with sodium hydroxide or potassium hydroxide as the force source electrode (cathode). When electrolysis was performed at an applied voltage of 0.9 V, oxygen was generated at about 3.5 μ \ / hydrogen at about 8.0 x l / h. The specific operation procedure is shown below.

(1) As an organic photocatalyst material, PV as an n-type semiconductor and CoPc or HPc as a p-type semiconductor were used. PV, H Pc and CoPc were each purified by sublimation.

twenty two

(2) The production of the organic photocatalytic device was performed by a vacuum evaporation method. As for the anode, PV was laminated with a thickness of 650 nm on an IT〇-coated glass substrate (manufactured by Nippon Sheet Glass Co., Ltd., resistance 10 Ωcm- ² ), and then CoPc was laminated with a thickness of 190 nm on the PV. Then it was cut into lcm x 1.5cm. For the cathode, HPc was deposited on a thermally decomposable graphite with a cross-sectional area of lcm x 1.5cm at a thickness of 190 nm and PV was applied.

2

The layers were stacked to a thickness of 650 marauders, and further carried platinum black.

(3) A portion corresponding to lcm × 0.5 cm of each electrode prepared in (2) was wiped off with acetone, and a lead wire was attached using a silver-containing epoxy adhesive (manufactured by Toyo Ink Mfg. Co., Ltd.). In order to prevent contact between the silver part and water, the electrode was insulated using an epoxy adhesive to form an organic photocatalyst-coated electrode.

[0151] (4) The photocatalytic reaction cell was produced by the following method. A single-chamber bipolar cell was constructed using the organic photocatalyst-coated electrode prepared in (3) above as both electrodes. In this case, the cell also has a function as a reference electrode due to the cell configuration. Alkaline water adjusted to pH-11 with sodium hydroxide or potassium hydroxide was used as the electrolyte solution.

(Hokuto Denko, HB-104), Coulomb meter (Hokuto Denko, HF-201) and XY recorder (Graphtec, WX-4000) equipped with a potentiometer / galvanostat (Hokuto Denko, HA-301), and a halogen lamp (150 W) was used as a light source. The product was analyzed using a gas chromatograph (GC-8A, manufactured by Shimadzu Corporation).

(6) At normal temperature and normal pressure, the anode electrode and the force source electrode were irradiated with light from the above light source, and electrolysis was performed at an applied voltage of about 0.9 V. μ 1 h— ¹ occurred. [0154] 2 OH— → 1/2 O + HO + 2e—

twenty two

According to the above Example 5, in the electrolysis of water employing an anode electrode and an organic sword electrode containing an organic photocatalyst, a photo-induced electrode is generated by irradiation with visible light, and hydrogen and oxygen are generated at an applied voltage (0.9 V) lower than the theoretical voltage. Occurrence was confirmed.

[0155] Example 6 (Existence of n solution using shrunken hornworm)

The electrode substrate / PV / CoPc is the anode electrode (anode), and the electrode substrate / H Pc / C is the force electrode (negative electrode).

2 60

As a pole, a bipolar cell as shown in Fig. 5 was constructed. When electrolysis was performed at an applied voltage of 0.9 V, about 3.0 μΐ / h of oxygen and about 6.0 μΐ / h of hydrogen were generated. The specific operation procedure is shown below.

(1) As an organic photocatalyst material, n-type semiconductor PV or C and p-type semiconductor

60

CoPc or HPc was used. PV, H Pc and CoPc were each purified by sublimation.

twenty two

(2) The production of the organic photocatalytic device was performed by a vacuum evaporation method. Regarding the anode, PV was coated on an ITO-coated glass substrate (Nippon Sheet Glass Co., Ltd., resistance 13 Ωcm- ² ; glass transmittance 85%; indium tin oxide laminated thickness 110 nm) with a thickness of 650 nm, and then PV On top, CoPc was laminated with a thickness of 190 nm. Then it was cut into lcm x 1.5cm. As for the cathode, as in the case of the anode, HPc is laminated on ITO at a thickness of 60 nm, C is laminated at a thickness of 120 nm, and platinum black is further supported.

2 60

[0158] (3) A portion corresponding to lcm x 0.5cm of each electrode prepared in (2) above was wiped with acetone, and a lead wire was used using a silver-containing epoxy adhesive (T-700, manufactured by Toyo Ink Mfg. Co., Ltd.). Attached. An organic photocatalyst-coated electrode was insulated using an epoxy-based adhesive to prevent contact of silver with water.

[0159] (4) The photocatalytic reaction cell was produced by the following method. A bipolar cell was constructed using the organic photocatalyst-coated electrode prepared in (3) above as both electrodes. For the electrolyte solution, use alkaline water adjusted to pH-11 with sodium hydroxide or potassium hydroxide in the reaction tank on the anode side, and acidic water adjusted to pH 2 with phosphoric acid or sulfuric acid in the reaction tank on the cathode side, respectively. Was. Furthermore, both tanks were connected by a salt bridge, and the tank was used as a reaction cell.

(5) The organic photocatalytic reaction was carried out using a measuring device as shown in FIG. Function generator (Hokuto Denko, HB-104), Coulomb meter (Hokuto Denko, HF-201) and XY recorder (Graphtec, WX-4000) equipped with a potentiometer / galvanostat (Hokuto Denko, HA-301), and a halogen lamp (150 W) was used as a light source. The product was analyzed using a gas chromatograph (GC-8A, manufactured by Shimadzu Corporation).

[0161] (6) At normal temperature and normal pressure, the anode electrode and the force source electrode were irradiated with light from the above-mentioned light source, and electrolysis was performed at an applied voltage of about 0.9 V. μ 1 h— ¹ occurred.

[0162] 2 OH— → 1/2 0 2 + H 20 + 2e—

According to Example 6 above, in the electrolysis of water using an anode electrode and a force source electrode containing an organic photocatalyst, a light-induced current is generated by irradiation with visible light, and hydrogen is applied at an applied voltage (0.9 V) lower than the theoretical voltage. Generation of oxygen was confirmed.

[0163] Example 7 (yes n horned anode, t-solution using shrinkage)

Electrode substrate / PV / CoPc is used as an anode electrode (anode), and a platinum rod is used as a force source electrode (cathode) using alkaline water adjusted to pH-11 with sodium hydroxide or potassium hydroxide as shown in Fig. 6. A bipolar cell was constructed. When electrolysis was performed at an applied voltage of 1.1 V, about 3.5 μ 約 / h of oxygen and about 8.0 μΐ / h of hydrogen were generated. The specific operation procedure is shown below.

(1) As an organic photocatalyst material, PV as an n-type semiconductor and CoPc as a p-type semiconductor were used. PV and CoPc used were each purified by sublimation.

(2) The production of the organic photocatalytic device was performed by a vacuum evaporation method. As for the anode, PV was laminated with a thickness of 650 nm on an ITO-coated glass substrate (manufactured by Nippon Sheet Glass Co., Ltd., resistance 10 Ωcm- ² ), and then CoPc was laminated with a thickness of 190 nm on the PV. Then it was cut into lcm x 1.5cm. A white gold bar was used as the cathode.

(3) A portion corresponding to lcm × 0.5 cm of the anode prepared in (2) was wiped off with acetone, and a lead wire was attached using a silver-containing epoxy adhesive (manufactured by Toyo Ink Mfg. Co., Ltd.). In order to prevent contact between the silver site and water, the electrode was insulated with an epoxy adhesive to form an organic photocatalyst-coated electrode.

[0167] (4) The photocatalytic reaction cell was produced by the following method. Using the organic photocatalyst-coated electrode prepared in (3) above as an anode and a platinum rod as a cathode, a single-chamber bipolar cell was constructed. In this case, the cell Has a function as a reference electrode. As the electrolyte solution, alkaline water adjusted to pH-11 with sodium hydroxide or potassium hydroxide was used.

(6) Under normal temperature and normal pressure, the anode electrode was irradiated with light without irradiating the force electrode with light, and electrolysis was performed at an applied voltage of about 1.1 V. As a result, oxygen was reduced to about 3.5 μ ¹ , Hydrogen was generated for about 8 μ1 h- ¹ .

[0170] 2 OH "→ 1/2 0 + H 0 + 2e—

From Example 7 above, in the electrolysis of water employing an anode electrode containing an organic photocatalyst and a force sword electrode made of platinum, a photo-induced electrode was generated by irradiation with visible light, and the applied voltage (1.1 V) was lower than the theoretical voltage. As a result, generation of hydrogen and oxygen was confirmed.

Claims

The scope of the claims

[I] An electrode material for electrolysis of water, comprising an organic photocatalyst containing a P-type organic semiconductor and an n-type organic semiconductor.

[2] The electrode material for electrolysis of water according to claim 1, wherein the p-type organic semiconductor is a macrocyclic ligand compound or a metal complex thereof.

3. The electrode material for water electrolysis according to claim 1, wherein the p-type organic semiconductor is at least one selected from the group consisting of a phthalocyanine derivative, a naphthalocyanine derivative, and a porphyrin derivative.

[4] The electrode material for electrolysis of water according to claim 1, wherein the n-type organic semiconductor is a polycyclic aromatic compound.

[5] The n-type organic semiconductor is at least one selected from the group consisting of fullerenes, carbon nanotubes, a conductive polymer doped with an electron donor, a perylene derivative, and a naphthalene derivative. 2. The electrode material for electrolysis of water according to 1.

[6] An electrode obtained by coating the surface of an electrode substrate with the electrode material for water electrolysis according to claim 1.

[7] The electrode according to claim 6, wherein the surface of the electrode substrate is coated with a first layer made of an n-type organic semiconductor and a second layer made of a p-type organic semiconductor. An anode electrode that supports a transition metal catalyst on the second layer.

[8] The electrode according to claim 6, wherein the surface of the electrode substrate is coated with a first layer made of a p-type organic semiconductor and a second layer made of an n-type organic semiconductor. A force sword electrode that supports a transition metal catalyst on the second layer.

[9] The electrode according to claim 6, wherein the electrode substrate is a conductive transparent glass substrate, a metal substrate, or a carbon-based substrate.

[10] An electrolysis apparatus for water comprising an electrode comprising the anode electrode according to claim 7 and the force sword electrode according to claim 8, a constant potential power supply, an aqueous electrolyte solution, and a light source.

11. The water electrolysis apparatus according to claim 10, wherein the anode electrode and the force sword electrode are connected to a constant potential power supply, and the anode electrode and the force sword electrode are immersed in an aqueous electrolyte solution.

12. The water electrolysis apparatus according to claim 11, wherein a voltage is applied to the anode electrode and the force source electrode with a constant potential power supply while irradiating the electrodes with light. .

13. The water electrolysis method according to claim 12, wherein the applied voltage is about 0.3 to 1.2 V.

[14] An electrode comprising the anode electrode and the force electrode according to claim 7, or an electrode comprising the force electrode and the anode electrode according to claim 8, a constant potential power supply, an aqueous electrolyte solution, and a light source. Water electrolysis equipment.

15. The water electrolysis apparatus according to claim 14, wherein the anode electrode and the force source electrode are connected to a constant potential power supply, and the anode electrode and the force source electrode are immersed in an aqueous electrolyte solution.

16. The water electrolysis apparatus according to claim 15, wherein a voltage is applied to the anode electrode and the force source electrode by a constant potential power supply while irradiating the electrodes with light. .

17. The method for electrolyzing water according to claim 16, wherein the applied voltage is about 1.0 to 1.4 V.

[18] The method for electrolyzing water according to claim 12, wherein the irradiation light is natural light.

19. The water electrolysis method according to claim 12, wherein oxygen is generated from the anode electrode, and hydrogen is generated from the force electrode.

[20] An organic photocatalyst containing a p-type organic semiconductor and an n-type organic semiconductor.

[21] The organic photocatalyst according to claim 20, wherein the p-type organic semiconductor is a macrocyclic ligand compound or a metal complex thereof.

22. The organic photocatalyst according to claim 20, wherein the p-type organic semiconductor is at least one selected from the group consisting of a phthalocyanine derivative, a naphthalocyanine derivative, and a porphyrin derivative.

[23] The organic photocatalyst according to claim 20, wherein the n-type organic semiconductor is a polycyclic aromatic compound.

[24] The n-type organic semiconductor is at least one selected from the group consisting of fullerenes, carbon nanotubes, a conductive polymer doped with an electron donor, a perylene derivative, and a naphthalene derivative. 4. The organic photocatalyst according to 1.