WO2017164191A1 - Photoélectrode, système photoélectrochimique pour la décomposition de l'eau et procédé de production d'une photoélectrode - Google Patents

Photoélectrode, système photoélectrochimique pour la décomposition de l'eau et procédé de production d'une photoélectrode Download PDF

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WO2017164191A1
WO2017164191A1 PCT/JP2017/011275 JP2017011275W WO2017164191A1 WO 2017164191 A1 WO2017164191 A1 WO 2017164191A1 JP 2017011275 W JP2017011275 W JP 2017011275W WO 2017164191 A1 WO2017164191 A1 WO 2017164191A1
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intermediate layer
photoelectrode
metal substrate
stainless steel
layer
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PCT/JP2017/011275
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English (en)
Japanese (ja)
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里英 斉藤
敬一 廣瀬
規史 長谷川
佐山　和弘
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イムラ・ジャパン株式会社
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/20—Vanadium, niobium or tantalum
    • B01J23/22—Vanadium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/133—Renewable energy sources, e.g. sunlight

Definitions

  • the present invention relates to a photoelectrode, a photoelectrochemical system for water splitting comprising the photoelectrode, and a method for producing the photoelectrode.
  • the photocatalyst is a semiconductor that receives light energy and causes charge separation (that is, electrons in the valence band are photoexcited in the conduction band and holes (holes, h + ) are formed in the valence band),
  • an oxidation-reduction reaction represented by the following formula: 2H 2 O ⁇ O 2 + 4H + + 4e ⁇ , 4H + + 4e ⁇ ⁇ 2H 2 (2H 2 O ⁇ O 2 + 2H 2 ) is catalyzed.
  • Examples of such a photocatalyst include compounds containing elements such as Ga, Zr, Ta, Si, Cd, Ti, Nb, Zn, Mo, Fe, Bi, W, V, Sn, As, and S. Solid semiconductors centering on titanium oxide (TiO 2 ) are known.
  • a photoelectrode including a conductive substrate and a photocatalyst layer made of the photocatalyst is used as an anode (anode), and oxygen is oxidized by oxidizing water at the anode with holes formed in the photocatalyst.
  • a water splitting method in which electrons photoexcited in the photocatalyst are moved to a cathode (cathode) as a counter electrode through an external circuit, and water is reduced by the cathode to generate hydrogen; the water is oxidized at the anode.
  • Patent Document 1 discloses a semiconductor optical device including a metal substrate having irregularities on its surface and a semiconductor layer formed on the surface of the metal substrate and made of a material having a photocatalytic action. It is described that water is decomposed using an electrode to produce hydrogen, and titanium (Ti) is used as the metal substrate, and titanium oxide and tungsten oxide are used as the materials having the photocatalytic action. Is described.
  • Non-patent Document 1 Yongqi Liang et al. Phys. Chem. C, 2011, 115, p. In 17594-17598 (Non-patent Document 1), a transparent conductive glass (FTO glass) substrate and a bismuth vanadate (BiVO 4 ) film are laminated in a photoelectrode via an intermediate layer of tin oxide (SnO 2 ). Is described.
  • Patent Document 1 a metal such as titanium used as a material for a metal substrate in Patent Document 1 is inferior in fine workability and expensive, so that when it is used as a conductive substrate for a photoelectrode, the economy is reduced. Had a problem. Further, since the FTO glass substrate used in Non-Patent Document 1 lacks flexibility, it has a problem that it is inferior in strength and formability.
  • One material that is inexpensive and excellent in strength and formability is stainless steel, but a photoelectrode using a stainless steel as a material for the conductive substrate has not been disclosed so far.
  • Patent Document 2 a first semiconductor layer, a second semiconductor layer, and an electrode layer are sequentially stacked, and the lower end of the conduction band of the first semiconductor layer.
  • a metal such as platinum is described as the electrode layer
  • SiC and WO 3 , TiO 2, Si, and the like are described as a combination of the first semiconductor and the second semiconductor.
  • the water splitting activity ability may still be insufficient.
  • JP 2006-297300 A International Publication No. 2012/137240
  • the present invention has been made in view of the above-described problems of the prior art, and includes a stainless steel material that is relatively inexpensive and excellent in strength and formability as a conductive substrate, and has excellent water splitting activity. It aims at providing the manufacturing method of an electrode, the photoelectrochemical system for water splitting provided with the said photoelectrode, and the said photoelectrode.
  • the present inventors have determined that in a photoelectrode having a conductive substrate and a photocatalyst layer, the conductive substrate is a metal substrate made of a stainless steel material, and the photocatalyst layer is a vanadine.
  • a layer made of bismuth acid, and the metal substrate and the photocatalyst layer are laminated via an intermediate layer made of tin oxide, thereby providing a stainless steel material as a conductive substrate and having excellent water splitting activity.
  • the inventors have found that a photoelectrode can be obtained, and have completed the present invention.
  • the photoelectrode of the present invention includes a metal substrate made of a stainless steel material, an intermediate layer made of tin oxide laminated on at least one surface of the metal substrate, and the metal substrate of the intermediate layer. And a photocatalyst layer made of bismuth vanadate stacked on the opposite surface.
  • the surface of the intermediate layer on the side in contact with the photocatalyst layer has an uneven shape.
  • the intermediate layer preferably has a thickness of 5 to 1000 nm.
  • the stainless steel material is preferably any one selected from the group consisting of austenitic stainless steel, ferritic stainless steel and martensitic stainless steel, and the tin oxide Preferably the product is stannic oxide.
  • the photoelectrode of the present invention preferably further comprises an oxide film on the surface of the metal substrate that is not covered with the intermediate layer.
  • the photoelectrochemical system for water splitting of the present invention comprises the photoelectrode of the present invention as a working electrode.
  • the method for producing the photoelectrode of the present invention comprises: Forming an intermediate layer made of tin oxide on at least one surface of a metal substrate made of a stainless steel material, and obtaining a laminate including the metal substrate and the intermediate layer; On the surface of the intermediate layer opposite to the metal substrate, a photocatalytic layer composed of bismuth vanadate is formed using a bismuth vanadate precursor solution containing V and Bi, and the metal substrate and the metal substrate A second step of obtaining a photoelectrode comprising: the intermediate layer laminated on at least one of the surfaces; and the photocatalytic layer laminated on a surface of the intermediate layer opposite to the metal substrate; Is included.
  • the photoelectrode manufacturing method of the present invention in the first step, at least one component selected from the group consisting of a vacuum deposition method, a sputtering method, an ion plating method, a plating method, an electrospinning method, and a thermal load spray method is used. It is preferable to form the intermediate layer by a film method under an inert gas atmosphere. Moreover, in the photoelectrode manufacturing method of the present invention, it is preferable that the method further includes a step of firing the laminate after the first step and before the second step.
  • the water splitting activity refers to a function of decomposing water and generating hydrogen when irradiated with light in an aqueous solution using the photoelectrode as a working electrode.
  • the photoelectrode will be described later.
  • the metal substrate made of a stainless steel material
  • the intermediate layer made of tin oxide, and the photocatalyst layer made of bismuth vanadate are sequentially laminated to form a specific combination.
  • the intermediate layer having an empty conduction band is disposed between the metal substrate and the photocatalyst layer.
  • the stainless steel material is made of a stainless steel material.
  • an intermediate layer is disposed between the metal substrate and the photocatalyst layer, the photocatalyst layer is a layer made of bismuth vanadate, and the intermediate layer is a layer made of tin oxide A combination of As a result, it is possible to provide a photoelectrode that is provided with a stainless steel material that is excellent in adhesion between the metal substrate, the intermediate layer, and the photocatalyst layer, is inexpensive, and has excellent strength and formability as a conductive substrate. The present inventors speculate.
  • the intermediate layer in the above specific combination, by forming the intermediate layer under an inert gas atmosphere, the intermediate layer is formed without being affected by the oxide film formed on the surface of the metal substrate made of a stainless steel material. Since the electrons are smoothly transferred between the metal substrate and the intermediate layer and the rectifying action of the electrons is further improved, a metal substrate made of a stainless steel material is provided as a conductive substrate. Regardless, the present inventors speculate that it has become possible to provide a photoelectrode excellent in water splitting activity.
  • a photoelectrode having a stainless steel material which is relatively inexpensive and excellent in strength and formability, as a conductive substrate and having excellent water splitting activity, and photoelectrochemistry for water splitting having the photoelectrode It is possible to provide a system and a method for manufacturing the photoelectrode.
  • FIG. 4 is a scanning electron microscope (SEM) photograph of the surface of a metal substrate used in Example 3.
  • FIG. 4 is a scanning electron microscope (SEM) photograph of the surface of the first intermediate layer after the formation of the first intermediate layer in Example 3.
  • FIG. 4 is a scanning electron microscope (SEM) photograph of the surface of the intermediate layer after formation of the intermediate layer having an uneven shape of Example 3.
  • FIG. 4 is an atomic force microscope (AFM) photograph of the intermediate layer surface obtained in Example 3.
  • FIG. It is a graph which shows the performance ratio of the photoelectrode of Example 3 with respect to the photoelectrode of Example 1.
  • the photoelectrode (photoelectrode 10) of the present invention includes a metal substrate (metal substrate 1) made of a stainless steel material and tin oxide laminated on at least one surface of the metal substrate. And a photocatalyst layer (photocatalyst layer 3) made of bismuth vanadate (BiVO 4 ) laminated on the surface of the intermediate layer opposite to the metal substrate.
  • the photoelectrode 10 may have a structure in which the intermediate layer 2 and the photocatalyst layer 3 are laminated on both surfaces thereof.
  • the metal substrate 1 functions as a conductive substrate for the photoelectrode 10.
  • the thickness of the metal substrate 1 is not particularly limited, but is preferably 0.1 to 1 mm, for example.
  • the surface in contact with the intermediate layer 2 may have an uneven shape.
  • the stainless steel material examples include an alloy containing iron and chromium, having an iron content of 50% by mass or more and a chromium content of 10.5% by mass or more. JIS (Japan Industry Standard 2005) ) Any of austenitic stainless steel, austenitic / ferritic stainless steel, ferritic stainless steel, martensitic stainless steel, precipitation hardened stainless steel as defined by the standard, and the shape and size of the desired photoelectrode, or economic efficiency Can be appropriately selected.
  • the stainless steel materials include austenitic stainless steel, ferritic stainless steel, and martensite from the viewpoint of excellent corrosion resistance, strength, and workability, and from the viewpoint of improving water splitting activity.
  • SUS304 is particularly preferable.
  • the intermediate layer 2 is disposed between the metal substrate 1 and the photocatalyst layer 3 described later in contact with the metal substrate 1 and the photocatalyst layer 3.
  • the surface opposite to the metal substrate 1, that is, the surface in contact with the photocatalyst layer 3 (hereinafter referred to as “intermediate layer catalyst surface” in some cases). ”)
  • the surface opposite to the metal substrate 1 that is, the surface in contact with the photocatalyst layer 3 (hereinafter referred to as “intermediate layer catalyst surface” in some cases).
  • having an uneven shape means having a three-dimensional shape in which concave portions and / or convex portions are randomly or regularly arranged two-dimensionally on the intermediate layer catalyst surface. Perforations and / or grooves are raised as the recesses.
  • a column cylinder, prismatic column; more preferably a vertical column provided in a direction perpendicular to the intermediate layer catalyst surface
  • a grain a dome, a cone (cone, pyramid; more preferably an intermediate layer catalyst surface)
  • a three-dimensional shape such as a polyhedron, and only one of them or a combination of two or more
  • the intermediate layer 2 preferably has a shape in which a plurality of convex portions are two-dimensionally arranged on the intermediate layer catalyst surface, and the three-dimensional shape of the convex portions is more preferably a column or a dome.
  • FIG. 2 a plurality of convex portions are arranged on the surface (intermediate layer catalyst surface) on the side where the intermediate layer 2 of the photoelectrode 10 is in contact with the photocatalyst layer 3.
  • the schematic longitudinal cross-sectional view in the case of having a shape is shown.
  • the convex portions are shown to be located at substantially equal intervals, and the vertical sectional shape of each convex portion is shown as a cube.
  • the convex portions are not necessarily located at regular intervals, and the vertical cross-sectional shape of the convex portions is not necessarily a cube.
  • the uneven shape can be confirmed by an atomic force microscope (AFM).
  • AFM atomic force microscope
  • the average roughness of the surface in the 2 ⁇ m ⁇ 2 ⁇ m region of the intermediate layer catalyst surface observed by an atomic force microscope is preferably 2 to 800 nm, and preferably 20 to 500 nm. Is more preferable.
  • the average interval of the convex portions in the 2 ⁇ m ⁇ 2 ⁇ m region observed by an atomic force microscope is preferably 20 to 1500 nm on the intermediate layer catalyst surface. 50 to 1000 nm is more preferable.
  • the interval between the convex portions refers to an interval between substantially vertex positions (top portions) of the convex portions on the intermediate layer catalyst surface.
  • the thickness of the intermediate layer 2 is preferably 5 to 1000 nm, preferably 5 to 500 nm, more preferably 10 to 300 nm.
  • the intermediate layer 2 is a layer made of tin oxide, More preferably, it is 5 to 210 nm, and particularly preferably 10 to 200 nm. If the thickness of the intermediate layer is less than the lower limit, it tends to be difficult to form a film, and the interface resistance between the metal substrate 1 and the photocatalyst layer 3 is increased, so that the water splitting activity ability is reduced or the external voltage is reduced. In the case of applying, there is a tendency that the size needs to be increased. On the other hand, when the upper limit is exceeded, the resistance between the conductive particles tends to increase and the hydrolytic activity tends to decrease.
  • the thickness of the intermediate layer 2 means an average thickness of the intermediate layer 2, and is measured from any 10 points in a 2 ⁇ m ⁇ 2 ⁇ m region, that is, from the interface with the metal substrate 1. It means the average of the distance to the surface of the intermediate layer catalyst surface.
  • middle layer 2 has the substantially bottom position of the location recessed from the interface with the metal substrate 1 under the said intermediate
  • the thickness of the intermediate layer 2 is preferably 5 to 500 nm, more preferably 10 to 300 nm, and the intermediate layer 2 is a layer made of tin oxide. In some cases, the thickness is more preferably 5 to 210 nm, and particularly preferably 10 to 200 nm.
  • the thickness of the intermediate layer 2 is preferably 5 to 1000 nm, more preferably 20 to 800 nm.
  • Examples of the tin oxide include tin oxide and a composite oxide of tin oxide and indium oxide.
  • examples of the tin oxide include stannous oxide (SnO), stannic oxide (SnO 2 ), and these.
  • Examples of the composite oxide include indium tin oxide (ITO: composite oxide of In 2 O 3 and SnO 2 ).
  • stannic oxide is used from the viewpoint that it has a tendency to exhibit particularly excellent water splitting activity when combined with a stainless steel material and bismuth vanadate, and from the viewpoint of cost. It is particularly preferred.
  • the intermediate layer 2 is a uniform layer made of the tin oxide from the viewpoint that when it is combined with a stainless steel material and bismuth vanadate, the water splitting activity tends to be particularly excellent.
  • the mass per unit area of the intermediate layer 2 is preferably 0.01 to 1.2 mg / cm 2 when the intermediate layer catalyst surface does not have an uneven shape, and the density of the tin oxide Is more preferably 0.1 to 1.2 mg / cm 2 from the viewpoint of further improving the water splitting activity ability.
  • the photocatalytic layer 3 is a layer that functions as a layer that receives light energy and causes charge separation. As shown in FIG. 1 or 2, the photocatalyst layer 3 is preferably laminated so as to cover the surface (intermediate layer catalyst surface) opposite to the metal substrate 1 of the intermediate layer 2.
  • the thickness of the photocatalyst layer 3 is preferably 80 to 1000 nm, and more preferably 100 to 600 nm.
  • the thickness of the photocatalyst layer 3 is less than the lower limit, the light absorptance is lowered and the water splitting activity is lowered.
  • the above upper limit is exceeded, the movement distance of electrons becomes long, charge recombination easily occurs, and the water splitting activity ability tends to decrease.
  • the thickness of the photocatalyst layer 3 means an average thickness of the photocatalyst layer 3, and the thickness of the photocatalyst layer 3 measured for any 10 points in the 2 ⁇ m ⁇ 2 ⁇ m region, that is, from the interface with the intermediate layer 2 The average of the distance to the surface of the photocatalyst layer 3 on the opposite side.
  • the thickness of the said photocatalyst layer 3 is made into the photocatalyst layer 3 from the substantially bottom position (bottom part) of a concave part under the said intermediate
  • the photoelectrode 10 preferably further includes an oxide film 4 on the surface of the metal substrate 1 that is not covered with the intermediate layer 2, and is covered with the intermediate layer 2 of the metal substrate 1. It is more preferable that all surfaces not covered are covered with the oxide film 4.
  • the thickness of the oxide film 4 is not particularly limited, but is preferably 1000 nm or less, for example, and more preferably 5 to 200 nm.
  • the photoelectrode 10 may be one in which a promoter is supported on the surface of the photocatalyst layer 3.
  • a promoter is supported on the surface of the photocatalyst layer 3.
  • co-catalyst those conventionally known as a co-catalyst for the photoelectrode can be appropriately used.
  • NiOOH / FeOOH, FeOOH, NiOOH , Co-P i, Co-B i, Ni-B i, Co 3 O 4 CoO, IrO x, MnO x, RuO x, RhO 2 , PtO 2 is preferable, and NiOOH / FeOOH, FeOOH, NiOOH, Co—P i , and Co—B i are more preferable.
  • the photoelectrode of the present invention can be used as an electrode for artificial photosynthesis technology.
  • Useful chemicals by oxidizing an aqueous solution containing sulfate ions, chloride ions, carbonic acid and hydrogencarbonate ions, iodate ions, etc. at the anode Persulfuric acid, hypochlorous acid, hydrogen peroxide, periodate, etc.
  • the photoelectrode of this invention is excellent in water splitting activity ability as mentioned above, it can be used suitably as an electrode (water splitting photoelectrode) of the following photoelectrochemical system for water splitting.
  • the photoelectrochemical system for water splitting of the present invention comprises the photoelectrode of the present invention as a working electrode.
  • the photoelectrode 10 working electrode
  • the photoelectrode 10 and the external circuit 12 are electrically used.
  • a counter electrode 11 connected thereto. At least a part of the photocatalyst layer 3 surface of the photoelectrode 10 and the counter electrode 11 are disposed so as to contact the solvent 14 accommodated in the container 15.
  • the material of the counter electrode 11 is not particularly limited, and examples thereof include metals such as platinum, gold, palladium, iron, copper, carbon, and stainless steel materials, and photoelectrodes other than the photoelectrode 10, among these, Platinum is preferable from the viewpoint of improving hydrogen generation efficiency when combined with the photoelectrode of the present invention in a hydrogen production apparatus, and the stainless steel material is preferable from the viewpoint of being relatively inexpensive and excellent in economy.
  • a material of the external circuit 12 A well-known thing can be utilized suitably as a material of conducting wire, For example, metals, such as platinum, gold
  • the solvent 14 examples include an aqueous electrolyte solution, and the aqueous electrolyte solution is preferably a supporting electrolyte-containing aqueous solution having a buffering action.
  • an alkali metal chloride, an alkali metal hydroxide, or an alkali metal carbonate is used. Examples thereof include a salt, an alkali metal sulfate, an alkali metal borate, an alkali metal phosphate, or a buffer solution containing two or more of these as an electrolyte.
  • the container 15 is preferably one that can transmit light, and examples thereof include a glass or plastic container.
  • the photoelectrochemical system 100 may further include an auxiliary power source 13 for applying a voltage between the photoelectrode 10 and the counter electrode 11 through the external circuit 12 as shown in FIG.
  • the auxiliary power source 13 include a potentiostat, a chemical battery, a capacitor, a renewable energy source (solar cell or the like), and the like.
  • the oxidation-reduction reaction rate can be drastically increased by applying such an external voltage.
  • the photoelectrochemical system for water splitting of the present invention uses the photoelectrode 10 having excellent water splitting activity of the present invention
  • the photoelectrode 10 is an anode and the counter electrode 11 (cathode) is a metal electrode.
  • the magnitude of the external voltage can be made sufficiently smaller (for example, 0.80 V or less) than the theoretical electrolysis voltage of water (1.23 V).
  • the band level of the photocatalyst used in these electrodes was compared with the water splitting standard electrode potential.
  • a standard electrode potential of water splitting half reaction 2H 2 O ⁇ 4H + + 4e ⁇ + O 2 (1.23 V vs. SHE (standard hydrogen electrode)) in the band gap of the anode photocatalyst
  • the standard electrode potential of the water splitting half reaction 4H + + 4e ⁇ ⁇ 2H 2 (0V vs.
  • the standard electrode potential of the redox species that functions as an electron carrier is the band gap of both photocatalysts.
  • the standard electrode potential (0V, 1.. In the case of a configuration in which 23V) exists, it is not necessary to apply an external voltage.
  • the water splitting efficiency is superior to the case where the photoelectrode is used for both electrodes, and the applied external voltage can be sufficiently reduced as described above.
  • a relatively inexpensive metal electrode can be used, it is possible to realize an economically reasonable hydrogen production cost.
  • the photoelectrochemical system 100 can be used as a hydrogen production apparatus.
  • the photocatalyst layer 3 is irradiated with light such as sunlight using the photoelectrode 10 as an anode and the counter electrode 11 as a cathode
  • the photocatalyst layer 3 is irradiated with light.
  • the holes formed in the photocatalyst layer 3 oxidize water at the anode to generate oxygen, and the electrons photoexcited in the photocatalyst layer 3 move to the counter electrode 11 through the external circuit 12.
  • the photoelectrochemical system for water splitting of the present invention is not limited to the form shown in FIG. 4.
  • the shape and size, the combination of the photoelectrode 10 and other photoelectrodes and / or semiconductor elements, and their arrangement may be adjusted as appropriate, and the container 15 may have a plurality of interiors such as the anode side and the cathode side.
  • the method for producing the photoelectrode of the present invention comprises: Forming an intermediate layer made of tin oxide on at least one surface of a metal substrate made of a stainless steel material, and obtaining a laminate including the metal substrate and the intermediate layer; On the surface of the intermediate layer opposite to the metal substrate, a photocatalytic layer composed of bismuth vanadate is formed using a bismuth vanadate precursor solution containing V and Bi, and the metal substrate and the metal substrate A second step of obtaining a photoelectrode comprising: the intermediate layer laminated on at least one of the surfaces; and the photocatalytic layer laminated on a surface of the intermediate layer opposite to the metal substrate; including.
  • the metal substrate made of a stainless steel material, the intermediate layer made of tin oxide, the photocatalyst layer made of bismuth vanadate, and the photoelectrode provided with these are as described in the photoelectrode of the present invention.
  • the first step is a step of forming an intermediate layer made of tin oxide on at least one surface of a metal substrate made of a stainless steel material to obtain a laminate including the metal substrate and the intermediate layer. is there.
  • the first step is under an inert gas atmosphere (preferably an oxygen concentration of 10% by volume or less). It is particularly preferred to carry out in Examples of the inert gas include nitrogen gas (N 2 ) and argon gas (Ar).
  • a vacuum deposition method, a sputtering method, an ion plating method are used when the intermediate layer catalyst surface does not have an uneven shape. It is preferably at least one film forming method selected from the group consisting of a plating method, an electrospinning method, and a thermal load spray method, more preferably a sputtering method and / or a thermal load spray method, and a kinetic energy of From the viewpoint of further improving the adhesion between the metal substrate and the resulting intermediate layer, and further increasing the density of the tin oxide and further improving the water splitting activity, it may be a sputtering method. Particularly preferred.
  • the tin oxide is used as a target, and the temperature is 400 ° C. or higher (in the inert gas atmosphere at a pressure of 3.5 Pa or less (more preferably 0.5 to 2.0 Pa)) (more Preferably, it is carried out under conditions of 350 to 550 ° C., more preferably 500 ° C.
  • a spray solution in which an organotin complex is dissolved in a solvent (2-ethylhexanoic acid, xylene, butyl acetate, etc.) is heated at a temperature in an inert gas atmosphere. It is preferable to spray the surface of the metal substrate heated to 350 ° C. or higher (more preferably 500 to 550 ° C.).
  • the intermediate layer catalyst surface has a concavo-convex shape
  • a film forming method for forming the intermediate layer made of tin oxide in the first step first, as in the case where the intermediate layer catalyst surface does not have a concavo-convex shape Then, after forming the layer made of the tin oxide (first intermediate layer), the method of forming the uneven shape made of the tin oxide on the surface thereof is preferable.
  • a method for forming the concavo-convex shape a conventionally known method or a method obtained by appropriately modifying a conventionally known method can be appropriately employed. Such methods include crystal growth; Hideki Masuda et al., J. MoI. Electrochem. Soc.
  • the first intermediate layer is impregnated with 1-100 mM tin fluoride (SnF 2 ) aqueous solution at room temperature to 200 ° C. for 1-24 hours, and then washed. It is preferable to form a shape in which convex portions made of a plurality of tin oxides are two-dimensionally arranged on the surface of the first intermediate layer by baking at 550 ° C. for 10 minutes to 1 hour.
  • SnF 2 1-100 mM tin fluoride
  • an Al film having a thickness of several ⁇ m is formed on the surface of the first intermediate layer by sputtering or vapor deposition, and nanoholes are penetrated in an acidic solution.
  • the first intermediate layer is impregnated with a tin organic compound solution or tin oxide sol or burned after Sn plating, and then the alumina film is removed with a solution such as phosphoric acid. It is preferable to obtain an intermediate layer having a shape in which convex portions made of a plurality of tin oxides are two-dimensionally arranged on the surface of the first intermediate layer.
  • a curable resin is applied to the surface of the first intermediate layer, and after forming a pattern by nanoimprinting, Sn plating is performed, or a tin organic compound or The first intermediate layer is impregnated with a tin oxide sol and then fired, or tin oxide is filled into the pattern by a vacuum deposition method or a sputtering method.
  • the intermediate layer or The metal substrate is preferably stored in acetone until the first intermediate layer is formed.
  • a photocatalyst layer made of bismuth vanadate is formed on the surface of the intermediate layer opposite to the metal substrate using a bismuth vanadate precursor solution containing V and Bi. This is a step of obtaining a photoelectrode.
  • the bismuth vanadate precursor solution is a solution containing V (vanadium) and Bi (bismuth), and preferably contains a compound containing V, a compound containing Bi, and a solvent.
  • the compound containing V include vanadium carboxylate, vanadium ammonium salt, vanadium pentoxide, and the like. One of these may be used alone, or two or more may be used in combination.
  • the Bi-containing compound include bismuth carboxylate, bismuth nitrate, bismuth oxide, and the like. One of these may be used alone, or two or more may be used in combination.
  • examples of the solvent include butyl acetate, acetate ester, xylene, dimethyl sulfoxide, aqueous nitric acid, and the like. One of these may be used alone, or two or more may be used in combination.
  • the content ratio of the compound containing V and the compound containing Bi is metal conversion (number of moles of V in the bismuth vanadate precursor solution: in the bismuth vanadate precursor solution).
  • the molar ratio of Bi is preferably 1: 1.
  • the bismuth vanadate precursor solution is formed on the surface of the intermediate layer opposite to the metal substrate.
  • a method of firing in the air after coating on the top.
  • the coating method include a spin coating method, a casting method, a spray coating method, a dip method (including electrodeposition), and among them, a spin coating method and a spray coating method are preferable.
  • the spin coating method it is preferably carried out at a temperature of 15 to 25 ° C. under conditions of 500 to 6000 rpm (more preferably 1000 to 5000 rpm).
  • the firing temperature is preferably 450 to 550 ° C., more preferably 500 to 550 ° C.
  • the firing time is preferably 0.5 to 6 hours, and more preferably 0.5 to 1 hour.
  • the method for producing a photoelectrode of the present invention further includes a step of firing the laminate after the first step and before the second step.
  • a step of firing the laminate By including such a step, an oxide film can be formed on the surface of the metal substrate not covered with the intermediate layer, and a photoelectrode excellent in corrosion resistance can be obtained.
  • the conditions for firing the laminate are a firing temperature of 300 to 550 ° C. (more preferably 500 ° C.) and a firing time of 0.5 to 6 hours (more preferably 0.5 to 1 hour) in air. Is preferred.
  • Example 1 First, after cleaning one surface (3.1 cm 2 ) of a 1.0 mm thick metal substrate made of SUS304 with acetone, a sputtering device (manufactured by Pascal Co., Ltd.) was used on the surface under an argon gas atmosphere ( An intermediate layer made of stannic oxide is formed under the conditions of an oxygen concentration of about 0% by volume, a target stannic oxide (SnO 2 ), a pressure of 2.0 Pa, and a temperature of 500 ° C., and the metal substrate and the intermediate layer A laminate comprising: was obtained. The thickness of the intermediate layer was set to 100 nm. Moreover, the mass per unit area of the intermediate layer was 0.2 mg / cm 2 . Next, the laminate was baked in air at 500 ° C. for 1.0 hour to form an oxide film on the entire surface of the metal substrate not covered with the intermediate layer.
  • a sputtering device manufactured by Pascal Co., Ltd.
  • EMOD coating agent vanadium manufactured by Kojundo Chemical Laboratory Co., Ltd.
  • EMOD coating agent bismuth manufactured by Kojundo Chemical Laboratory Co., Ltd.
  • a bismuth vanadate precursor solution having a molar ratio with Bi (V: Bi) of 1: 1 was prepared.
  • the prepared bismuth vanadate precursor solution was spin-coated at 1000 rpm at a temperature of 25 ° C. on the surface of the intermediate layer opposite to the metal substrate.
  • the photocatalyst layer which consists of bismuth vanadate was formed by baking at 500 degreeC for 0.5 hour in the air, and the photoelectrode by which the metal substrate / intermediate layer / photocatalyst layer was laminated
  • the thickness of the photocatalyst layer was set to 100 nm.
  • Example 2 First, one surface (3.1 cm 2 ) of a metal substrate made of SUS304 having a thickness of 1.0 mm is washed with acetone, and then an ITO film is formed on the surface by sputtering to form an intermediate layer. And a laminate comprising the intermediate layer. The thickness of the intermediate layer was set to 300 nm. A photoelectrode in which the metal substrate / intermediate layer / photocatalyst layer was sequentially laminated was obtained in the same manner as in Example 1 except that this laminate was used in place of the laminate of Example 1.
  • a potentiostat is connected to the metal substrate of each photoelectrode obtained in Examples 1 and 2 and Comparative Example 1 via a lead, and the potentiostat is connected to the reference electrode (silver-silver chloride electrode) and the light via the lead.
  • An electrode counter electrode platinum electrode
  • the photoelectrode, the reference electrode, and the counter electrode are placed so as to be immersed in a hole scavenger (sodium sulfite) -containing alkali metal borate aqueous solution (sodium borate buffer solution, pH 8.5), and solar photocatalyst layer surface of the photoelectrode Light (simulated sunlight, intensity: 100 mW / cm 2 ) was irradiated with a simulator to obtain a current density-versus-silver-silver chloride electrode voltage curve. Also, the current density vs. RHE voltage curve (current vs. voltage characteristic curve) was obtained by converting the voltage vs. silver-silver chloride electrode voltage into the voltage vs.
  • a hole scavenger sodium sulfite
  • alkali metal borate aqueous solution sodium borate buffer solution, pH 8.5
  • solar photocatalyst layer surface of the photoelectrode Light simulated sunlight, intensity: 100 mW /
  • FIG. 5 shows current-voltage characteristic curves obtained using the photoelectrodes of Example 1 and Comparative Example 1
  • FIG. 6 shows current-voltage characteristic curves obtained using the photoelectrodes of Example 2 and Comparative Example 1. Respectively.
  • the current density measured when water is decomposed even though the stainless steel material is provided as the conductive substrate. Is large, that is, it exhibits excellent water splitting activity and exhibits good performance as a photoelectrode.
  • Example 3 First, after cleaning one surface (3.1 cm 2 ) of a 1.0 mm thick metal substrate made of SUS304 with acetone, a sputtering device (manufactured by Pascal Co., Ltd.) was used on the surface under an argon gas atmosphere (A first intermediate layer made of stannic oxide is formed under conditions of an oxygen concentration of about 0% by volume), a target stannic oxide (SnO 2 ), a pressure of 2.0 Pa, and a temperature of 500 ° C., and the metal substrate and the A laminate comprising a first intermediate layer was obtained. The thickness of the first intermediate layer was set to 65 nm.
  • FIG. 7 shows a scanning electron microscope (SEM) photograph of the surface of the metal substrate
  • FIG. 8 shows a scanning electron microscope photograph of the surface of the first intermediate layer after the formation of the first intermediate layer, and an intermediate layer having an uneven shape.
  • FIG. 1 Scanning electron micrographs of the intermediate layer surface after formation are shown in FIG. Further, an atomic force microscope (AFM) photograph of the obtained intermediate layer surface is shown in FIG. On the surface of the obtained intermediate layer, the average roughness of the surface in the 2 ⁇ m ⁇ 2 ⁇ m region observed by an atomic force microscope was about 80 nm.
  • AFM atomic force microscope
  • the laminate was fired in air at 500 ° C. for 1.0 hour to form an oxide film on the entire surface of the metal substrate not covered with the intermediate layer.
  • 0.2 part by mass of EMOD coating agent vanadium (manufactured by Kojundo Chemical Laboratory Co., Ltd.) and 0.2 part by mass of EMOD coating agent bismuth (manufactured by Kojundo Chemical Laboratory Co., Ltd.) are diluted with butyl acetate.
  • a bismuth vanadate precursor solution having a molar ratio with Bi (V: Bi) of 1: 1 was prepared.
  • the prepared bismuth vanadate precursor solution was spin-coated at a temperature of 25 ° C. and 5000 rpm on the surface of the intermediate layer opposite to the metal substrate.
  • the thickness of the photocatalyst layer was set to 100 nm.
  • a stainless steel material that is relatively inexpensive and excellent in strength and formability is provided as a conductive substrate, and a photoelectrode excellent in water splitting activity and the photoelectrode are provided. It is possible to provide a photoelectrochemical system for water splitting and a method for producing the photoelectrode.

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Abstract

La présente invention concerne une photoélectrode qui comprend : un substrat métallique comprenant un matériau en acier inoxydable ; une couche intermédiaire, comprenant de l'oxyde d'étain, stratifiée sur au moins l'une des surfaces du substrat métallique ; et une couche de photocatalyseur, comprenant du vanadate de bismuth, stratifiée sur la surface opposée du substrat métallique par rapport à la couche intermédiaire.
PCT/JP2017/011275 2016-03-22 2017-03-21 Photoélectrode, système photoélectrochimique pour la décomposition de l'eau et procédé de production d'une photoélectrode WO2017164191A1 (fr)

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JP2021146313A (ja) * 2020-03-23 2021-09-27 学校法人 龍谷大学 構造体およびその製造方法
WO2022107315A1 (fr) * 2020-11-20 2022-05-27 日本電信電話株式会社 Photoélectrode à semi-conducteur et procédé de fabrication de photoélectrode à semi-conducteur
EP4101811A1 (fr) 2021-06-07 2022-12-14 Hitachi, Ltd. Cellule de production d'hydrogène

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JP2011174164A (ja) * 2010-01-29 2011-09-08 Sanyo Electric Co Ltd 電解用電極、及びその電極の製造方法
JP2011213553A (ja) * 2010-03-31 2011-10-27 Mitsubishi Chemicals Corp 水素製造装置
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JP2011174164A (ja) * 2010-01-29 2011-09-08 Sanyo Electric Co Ltd 電解用電極、及びその電極の製造方法
JP2011213553A (ja) * 2010-03-31 2011-10-27 Mitsubishi Chemicals Corp 水素製造装置
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Publication number Priority date Publication date Assignee Title
JP2021146313A (ja) * 2020-03-23 2021-09-27 学校法人 龍谷大学 構造体およびその製造方法
JP7461635B2 (ja) 2020-03-23 2024-04-04 学校法人 龍谷大学 構造体およびその製造方法
WO2022107315A1 (fr) * 2020-11-20 2022-05-27 日本電信電話株式会社 Photoélectrode à semi-conducteur et procédé de fabrication de photoélectrode à semi-conducteur
JP7485991B2 (ja) 2020-11-20 2024-05-17 日本電信電話株式会社 半導体光電極および半導体光電極の製造方法
EP4101811A1 (fr) 2021-06-07 2022-12-14 Hitachi, Ltd. Cellule de production d'hydrogène

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