WO2022024747A1 - Water-splitting device and method for producing gas - Google Patents
Water-splitting device and method for producing gas Download PDFInfo
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- WO2022024747A1 WO2022024747A1 PCT/JP2021/026291 JP2021026291W WO2022024747A1 WO 2022024747 A1 WO2022024747 A1 WO 2022024747A1 JP 2021026291 W JP2021026291 W JP 2021026291W WO 2022024747 A1 WO2022024747 A1 WO 2022024747A1
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- WIPO (PCT)
- Prior art keywords
- photocatalyst
- aqueous solution
- surfactant
- water
- gas
- Prior art date
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Images
Classifications
-
- 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
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/66—Silver or gold
- B01J23/68—Silver or gold with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/04—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of inorganic compounds, e.g. ammonia
-
- 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
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
-
- 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
Definitions
- the present invention relates to a water splitting device and a method for producing a gas.
- Patent Document 1 a base material with a photocatalyst having a base material and a photocatalyst fixed on the base material is placed in water, and the base material with a photocatalyst is irradiated with light to decompose water.
- Methods for producing at least one of hydrogen and oxygen are disclosed.
- an object of the present invention is to provide a water splitting device having an excellent initial amount of gas generated and a method for producing gas.
- the present inventors fixed the container containing the aqueous solution containing the surfactant on the photocatalytic substrate or the inner wall surface of the container immersed in the aqueous solution.
- water splitting was carried out using a water splitting device having the photocatalyst, it was found that the initial amount of gas generated was excellent.
- a container containing an aqueous solution containing a surfactant It has a base material and a photocatalyst-attached base material having a photocatalyst fixed on the base material, or a photocatalyst fixed on the inner wall surface of the container, which is immersed in the aqueous solution.
- a water decomposition device that generates gas from the photocatalyst by irradiating the photocatalyst with light.
- the photocatalyst comprises at least one photocatalytic compound selected from the group consisting of oxides, oxynitrides, nitrides and chalcogenide compounds.
- the photocatalyst compounds are Sr, Na, Mg, Al, Si, Ca, Ti, V, Fe, Cu, Zn, Ga, Y, Zr, Nb, Ag, In, Sn, Ba, La, Ta, W and Bi.
- the water splitting apparatus according to any one of [1] to [5], which comprises at least one element selected from the group consisting of.
- the embodiment of the water splitting apparatus of this invention is schematically an end view. It is a schematic diagram which shows the gas generation amount measurement system used in the Example column.
- the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
- the visible light is light having a wavelength visible to the human eye among electromagnetic waves, and specifically, light in a wavelength range of 380 to 780 nm.
- the water splitting apparatus of the present invention is a container containing an aqueous solution containing a surfactant, a base material with a photocatalyst having a base material and a photocatalyst fixed on the base material, or a base material having a photocatalyst, which is immersed in the aqueous solution.
- the water splitting apparatus of the present invention is excellent in the initial amount of gas generated. The details of this reason have not been clarified, but it is presumed that it is due to the following reasons.
- Examples of the water splitting device include a photocatalyst-equipped substrate in which a photocatalyst in which a hydrogen generation reaction and an oxygen generation reaction occur on the same particle is immobilized on the substrate, and a photocatalyst in which a hydrogen generation reaction and an oxygen generation reaction occur on the same particle.
- the photocatalyst immobilized on the inner wall surface of the container, the photocatalyst-equipped substrate in which the photocatalyst compound for hydrogen generation and the photocatalyst compound for oxygen generation are immobilized on the substrate, and the photocatalyst compound for hydrogen generation and the photocatalyst compound for oxygen generation are inside.
- An embodiment having a photocatalyst immobilized on a wall surface can be mentioned.
- FIG. 1 is an end view schematically showing a water splitting device 1 which is an example of the water splitting device of the present invention.
- the water splitting device 1 has a container 10 filled with an aqueous solution S containing a surfactant, and a photocatalytic substrate 20 arranged in the container 10.
- the photocatalyst-attached base material 20 has a base material 22 and a photocatalyst 24 fixed on the base material 22.
- the base material 20 with a photocatalyst 20 is arranged in the container 20 at a position where the photocatalyst 24 can receive light L.
- the water decomposition device 1 is a device that generates a gas from the surface of the photocatalyst 24 by irradiation with light L. Specifically, irradiation of the photocatalyst 24 with light L causes decomposition of water on the surface of the photocatalyst 24, and at least one of oxygen and hydrogen is generated.
- the light L to be irradiated visible light such as sunlight, ultraviolet light, infrared light and the like can be used, and among them, sunlight whose amount is inexhaustible is preferable.
- the container 10 is a container that contains the aqueous solution S and is used for installing the base material 20 with a photocatalyst.
- the shape of the container 10 is not particularly limited as long as it can accommodate the aqueous solution S and the base material 20 with a photocatalyst can be installed.
- Specific examples of the material constituting the container 10 are preferably a material having excellent corrosion resistance, and examples thereof include polyacrylate, polymethacrylate, polycarbonate, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polyethylene naphthalate, glass, and metal. ..
- the aqueous solution S is an aqueous solution in which a surfactant is dissolved in water, and is contained in a container 10.
- the aqueous solution S is a raw material used for water decomposition.
- Specific examples of the surfactant include ionic surfactants such as cationic surfactants, anionic surfactants and amphoteric surfactants, and nonionic surfactants.
- the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, aromatic quaternary ammonium salts, benzalkonium chloride salt, benzethonium chloride, pyridinium salt, imidazolinium salt and the like. ..
- Specific examples of the anionic surfactant include carboxylates, sulfonates (eg, alkyl sulfonates, alkylbenzene sulfonates), sulfate ester salts, phosphate ester salts and the like.
- amphoteric tenside examples include carboxybetaine type, sulfobetaine type, aminocarboxylate, imidazolinium betaine, lecithin, alkylamine oxide and the like.
- nonionic surfactants include polyoxyethylene higher alkyl ethers, polyoxyethylene higher alkylphenyl ethers, polyoxyethylene glycol higher fatty acid diesters, silicone-based surfactants, and fluorine-based surfactants. Agents and the like can be mentioned.
- a fluorine-based surfactant in which a part of the carbon-hydrogen bond is replaced with a carbon-fluorine bond is preferably used because of its excellent stability.
- the surfactant may be used alone or in combination of two or more.
- the surfactant does not have a hydroxy group, an alkoxy group, and an ether bond that are easily oxidized on the photocatalyst surface because it can exist stably on the photocatalyst surface and the initial amount of gas generated is more excellent.
- Aromatic rings eg, benzene, etc. that are easily oxidized by active oxygen species produced as reaction intermediates for water splitting, because the surfactant can exist stably during the water splitting reaction and the amount of initial gas generated is excellent. It is preferable not to have an aromatic hydrocarbon ring and an aromatic heterocycle such as imidazole, pyrazole and pyridine).
- the surfactant contains a compound represented by the formula I because the elapsed value of the hydrogen generation rate is excellent (that is, the decrease in the hydrogen generation rate can be suppressed when the photocatalyst is irradiated with light for a long time). It is preferable, and it is particularly preferable that the compound is represented by the formula I.
- R 1 is an alkyl group having 4 to 20 carbon atoms.
- the alkyl group in R 1 may be linear, branched or cyclic.
- the number of carbon atoms of the alkyl group in R1 is 4 to 20, and 6 to 18 is preferable, and 8 to 16 is particularly preferable, because the initial amount of gas generated and the elapsed value of the hydrogen generation rate are more excellent.
- R 2 , R 3 and R 4 are independently alkyl groups. However, the carbon number of the alkyl group in R2 , R3 and R4 is less than or equal to the carbon number of the alkyl group of R1 .
- the lower limit of the number of carbon atoms of the alkyl group in R 2 , R 3 and R 4 is 1.
- the alkyl groups in R2 to R4 may be linear, branched or cyclic. R2 to R4 may be the same or different.
- X ⁇ is a halide ion or a hydroxide ion.
- a halide ion is preferable, and F ⁇ , Cl ⁇ , or Br ⁇ is more preferable because it is excellent in stability during a water splitting reaction.
- the oxidation peak potential of the aqueous solution is 1 because the surfactant molecules are less likely to be oxidized on the surface of the photocatalyst and can exist stably, and the initial gas generation amount is excellent.
- .0V vs. It is preferably RHE or higher, and 1.3 V vs. RHE or higher is more preferable, 1.6 V vs. RHE or higher is particularly preferable.
- the upper limit of the oxidation peak potential of the aqueous solution is not particularly limited, but is 3.0 V vs. RHE or less is preferable.
- RHE is an abbreviation for reversible hydrogen electrode.
- the oxidation peak potential of the aqueous solution can be measured by the method described in the Example column described later. In addition, 0.5V vs. Since the oxidation peak potential appearing below RHE is the oxidation peak potential derived from the platinum electrode used for the measurement, 0.5 V vs. The oxidation peak potential that appears above RHE is the oxidation peak potential of the aqueous solution.
- a surfactant having no aromatic ring is contained, and the oxidation peak potential of the aqueous solution is 1.0 V vs. Examples thereof include RHE and above.
- an excellent water splitting device can be obtained due to the initial amount of gas generated.
- One of the preferred embodiments of the aqueous solution in the present invention is a surfactant containing an aromatic ring, a hydroxy group, an alkoxy group, and an ether bond, and the oxidation peak potential of the aqueous solution is 1.0 V vs. Examples thereof include RHE and above.
- a water splitting device having an excellent hydrogen generation rate can be obtained.
- One of the preferred embodiments of the aqueous solution in the present invention includes an embodiment containing a surfactant satisfying the above formula I. As a result, a water splitting device having an excellent elapsed value of the hydrogen generation rate can be obtained.
- the lower limit of the concentration of the surfactant in the aqueous solution is the critical micelle concentration peculiar to the surfactant because the decrease in surface tension makes it easier for bubbles to separate from the surface of the photocatalyst and the diffusion of the gas generated by water splitting is excellent. 0.25 times or more of (CMC) is preferable, 0.5 times or more of CMC is more preferable, and 1 time or more of CMC is particularly preferable.
- the upper limit of the concentration of the surfactant in the aqueous solution is preferably 20 times or less of CMC, more preferably 10 times or less of CMC, and particularly preferably 5 times or less of CMC from the viewpoint of avoiding cloudiness of the aqueous solution.
- the surface tension of water is measured by changing the concentration of the surfactant with a surface tension meter (manufactured by Kyowa Surfactant), and the surface tension and the surface are measured.
- the concentration of the turning point in the tension plot (the lowest concentration at which the decrease in surface tension due to the increase in surfactant concentration is contained and the surface tension value becomes constant) is determined as the CMC value.
- the CMC value can also be obtained by an electric conduction method, a dye method, a fluorescence method, or a viscosity method.
- the CMC values of various surfactants described in the literature such as M. J. Rosen, J. T. Kunjappu, Surfactants and interfacial phenomena, 4th edition, John Wiley & Sons (2012) can also be referred to.
- the photocatalyst-attached base material 20 has a base material 22 and a photocatalyst 24 immobilized on the base material 22.
- the base material 20 with a photocatalyst is immersed in the aqueous solution 10 so that the photocatalyst 24 comes into contact with the aqueous solution 10.
- the base material 22 is a member that supports the photocatalyst 24.
- Specific examples of the material constituting the base material 22 include metals, organic compounds (for example, polyacrylate, polymethacrylate, polycarbonate, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polyethylene naphthalate), inorganic compounds (for example, SrTiO 3 and the like). Metal oxides, glass, ceramics).
- the shape of the base material 22 is not particularly limited, and may be a flat plate shape, a punching metal shape, a mesh shape, a lattice shape, or a porous body having penetrating pores.
- the thickness of the base material 22 is not particularly limited and can be appropriately selected depending on the size of the container 10.
- the base material 22 has a single-layer structure, but the base material 22 may have a multi-layer structure.
- the base material 22 may include a support layer and a conductive layer arranged on the support layer.
- the material constituting the support layer include the material constituting the above-mentioned base material 22.
- Materials constituting the conductive layer include metals (for example, Sn, Ti, Ta, Au), SrRuO 3 , ITO (indium tin oxide), and zinc oxide-based transparent conductive materials (Al: ZnO, In: ZnO, Ga: ZnO, etc.).
- metal atom: metal oxide such as Al: ZnO
- a part of the metal (Zn in the case of Al: ZnO) constituting the metal oxide is referred to as a metal atom (Al: ZnO). In the case, it means the one replaced with Al).
- the photocatalyst 24 is fixed on the base material 22.
- a gas specifically, at least one of oxygen and hydrogen
- the photocatalyst 24 is arranged on a part of the base material 22, but may be arranged on the whole of the base material 22.
- the photocatalyst 24 may exist in a form in which a plurality of photocatalyst particles are continuously present on the base material 22 (that is, a form constituting the photocatalyst layer), or a plurality of photocatalyst particles are present on the base material 22. It may exist in a form that exists discontinuously.
- the thickness of the photocatalyst layer is preferably 0.1 to 1000 ⁇ m, and particularly preferably 1 to 100 ⁇ m.
- the method for immobilizing the photocatalyst 24 on the substrate 22 is not particularly limited, and for example, the photocatalyst particles are dispersed in a solvent to form a suspension (slurry), and the suspension is applied onto the substrate.
- a solvent examples include water, alcohols such as methanol and ethanol, ketones such as acetone, benzene, toluene and xylene.
- the photocatalyst particles can be uniformly dispersed in the solvent by performing ultrasonic treatment.
- the surfactant remaining in the photocatalyst layer reduces the reaction efficiency of the photocatalyst.
- Suspensions that do not contain are preferred.
- the method of applying the suspension on the substrate is not particularly limited, and for example, a drop casting method, a spray method, a dip method, a squeegee method, a doctor blade method, a spin coating method, a screen coating method, a roll coating method, and an inkjet method.
- Known methods such as a method and a particle transfer method can be mentioned.
- the temperature may be maintained at a temperature equal to or higher than the boiling point of the solvent.
- Examples of the material constituting the photocatalyst 24 include at least one photocatalyst compound selected from the group consisting of oxides, oxynitrides, nitrides and chalcogenide compounds.
- Photocatalytic compounds are from Sr, Na, Mg, Al, Si, Ca, Ti, V, Fe, Cu, Zn, Ga, Y, Zr, Nb, Ag, In, Sn, Ba, La, Ta, W and Bi. It is preferable to contain at least one element selected from the group.
- One of the preferred embodiments of the photocatalyst 24 includes an embodiment containing both a photocatalyst compound for hydrogen generation and a photocatalyst compound for oxygen generation.
- Specific examples of the photocatalyst compound for hydrogen generation include oxynitrides such as BaNbO 2 N, BaTaO 2 N, LaTIO 2 N, and TaON, nitrides such as Ta 3 N 5 , and Y 2 Ti 2 O 5 S 2 , and so on.
- CZTS compound semiconductor such as Cu 2 ZnSnS 4 , Cr.
- SrTIO 3 doped with at least one element selected from the group consisting of, Rh, Ta and Ir, and is not limited to the materials exemplified here, but is excellent in gas generation amount and durability.
- CIGS compound semiconductors nitrides such as Ta 3 N 5 , and BaTaO 2 N, LaTIO 2 N and Acid nitrides such as TaON are preferred.
- Specific examples of the photocatalytic compound for oxygen generation include oxides such as TIO 2 , Fe 2 O 3 , WO 3 , BiVO 4 , and Bi 2 WO 6 in addition to those exemplified for the photocatalytic compound for hydrogen generation.
- Nitrides such as 5 and oxynitrides such as BaTaO 2 N, LaTIO 2 N and TaON are preferred.
- One of the preferred embodiments of the photocatalyst 24 is a solid solution of GaN and ZnO, an oxynitride such as LaTIO 2 N and TaON, a nitride such as Ta 3 N 5 , Na 2 Ti 6 O 13 , SnNb 2 O 6 , BaTi.
- KTaO 3 doped with at least one element selected from the group consisting of 4 O 9 , Na, Al, Cr, Ni, Rh, Sb and Ta hereinafter, also referred to as “specific element”
- specific element include SrTiO 3 and at least one photocatalytic compound selected from the group consisting of TiO 2 doped with a specific element.
- These photocatalytic compounds can generate both oxygen and hydrogen gases by water splitting with light irradiation. Of these, SrTiO 3 doped with a specific element is preferable from the viewpoint of excellent gas generation amount and durability.
- the photocatalyst 24 may have a co-catalyst supported on its surface. If a co-catalyst is supported, the gas generation efficiency becomes better.
- the method for supporting the co-catalyst is not particularly limited, and can be formed by, for example, a coating firing method, a photoelectric deposition method, a vacuum vapor deposition method, a sputtering method, an impregnation method, or the like.
- Examples of the material constituting the co-catalyst include simple substances composed of Pt, Pd, Ni, Au, Ag, Ru, Cu, Co, Cr, Rh, Ir, Mn and the like, alloys obtained by combining them, and the like. Oxides can be mentioned.
- the size of the co-catalyst is not particularly limited, and is preferably 0.5 nm to 1 ⁇ m and a height of about several nm.
- the gas generated near the surface of the photocatalyst 24 can be recovered, for example, from a pipe (not shown) connected to the container 10. Further, a supply pipe (not shown), a pump, or the like for supplying the aqueous solution S may be connected to the container 10. Further, the water splitting device 1 may have a light source (xenon lamp or the like) (not shown) when sunlight is not used as the light L.
- a light source xenon lamp or the like
- the water splitting device of the present invention uses a photocatalyst fixed on the inner wall surface of the container instead of the base material with a photocatalyst. It may be a mode to have.
- the photocatalyst may be immobilized at any position on the inner wall surface of the container as long as it is arranged at a position where it is immersed in the aqueous solution.
- the method of immobilizing the photocatalyst on the inner wall surface of the container is not particularly limited, and examples thereof include the same method as the method of immobilizing the photocatalyst on the substrate.
- the method for producing a gas of the present invention is a method for producing a gas using the above-mentioned water decomposition apparatus of the present invention, and by irradiating the photocatalyst of the above-mentioned water decomposition apparatus with light, gas is removed from the surface of the above-mentioned photocatalyst. generate.
- Examples of the generated gas include hydrogen and oxygen.
- the initial amount of gas generated is excellent.
- Example 1 Manufacturing of base material with photocatalyst
- powder of SrTiO 3 : Al which is a photocatalyst carrying RhCrO x , which is a hydrogen generation assisting catalyst, and hydrophilic silica particles are prepared.
- Dispersed in pure water by ultrasonic treatment to obtain a suspension containing no surfactant.
- This suspension was drop-cast on a glass plate, dried and immobilized, and cut into a 3 cm square square to obtain a photocatalytic substrate.
- SrTiO 3 : Al means SrTiO 3 doped with Al.
- Aqueous solution S1 is prepared by mixing and stirring dodecyltrimethylammonium bromide and pure water so that the concentration of dodecyltrimethylammonium bromide (cationic surfactant; see formula I-1 below) is as shown in Table 1.
- the oxidation peak potential of the aqueous solution S1 was measured by electrochemical measurement using an electrochemical measurement system (Hokuto Denko, HZ-7000). Specifically, a reaction vessel made of borosilicate glass (diameter 6 cm, height 7 cm) is used, a platinum (Pt) wire is used as the working electrode and the counter electrode, and an Ag / AgCl electrode (Toyo Technica, TRE-10D-200) is used as the reference electrode. -INAGSE-20) was used.
- Sodium dihydrogen phosphate (NaH 2 PO 4 , 0.05 mL / L) and disodium hydrogen phosphate (Na 2 HPO 4 , 0.05 mol / L) were added to the aqueous solution S1 as supporting electrolytes.
- 0.1 L of the aqueous solution S1 to which the supporting electrolyte is added is poured into the reaction vessel, argon is allowed to flow in the reaction vessel for 10 minutes, and then electrochemical measurement is performed by a cyclic voltammetry method to determine the oxidation peak potential of the aqueous solution S1. I asked.
- the sweep range is -0.1 V vs. RHE ⁇ 1.8V vs.
- the number of bubbles detached from the surface of the photocatalyst within the observation range and time was measured, and the aqueous solution with respect to the number of bubbles detached in pure water.
- the number of bubbles leaving was compared and evaluated. It can be said that the larger the number of bubbles released, the larger the initial amount of gas generated.
- the evaluation criteria are as follows, and the results are shown in Table 1.
- C The number of bubble separations is 1 times or less compared to pure water
- the gas generation amount measuring system 500 includes a water decomposition device 100, a closed circulation reaction system 200 for an automatic double photocatalyst, a xenon lamp 300, and a gas chromatograph 400.
- the water decomposition apparatus 100 has a reaction vessel 110 containing the aqueous solution S1 and a photocatalytic substrate 120 immersed in the aqueous solution S1.
- the closed circulation reaction system 200 for an automatic double photocatalyst includes a pressure gauge 210, a circulation pump 220, a vacuum pump 230, and a pipe 240 connecting each member. Specifically, a base material 120 with a photocatalyst was placed on the bottom surface of the reaction vessel 110, and 0.1 L of the aqueous solution S1 was poured.
- This reaction vessel 110 is connected to a closed circulation reaction system 200 for an automatic double photocatalyst, degassed under a reduced pressure of 10 Pa by a vacuum pump 230 for 1 hour, and then argon (Ar) is introduced to introduce 10 kPa. And said. Then, the base material 120 with a photocatalyst was irradiated with light L1 from the xenon lamp 300, and the amount of hydrogen and oxygen gas generated in the reaction vessel 110 was measured every hour by the gas chromatograph 400.
- the "hydrogen generation rate” (hydrogen gas generation amount per hour) was calculated from the hydrogen gas generation amount 0 to 3 hours after the start of light irradiation, and used as the "initial value" of the hydrogen generation rate.
- aqueous solution with respect to the "initial value" of an aqueous solution (hereinafter, also referred to as “reference aqueous solution”) having a concentration of octylphenol ethoxylate (Dow, TRITON (registered trademark) X-100, nonionic surfactant) of 1 mmol / L.
- the "initial value” in S1 was compared and evaluated.
- the evaluation criteria are as follows, and the results are shown in Table 1.
- the initial value of the hydrogen generation rate is more than 4 times that of the reference aqueous solution
- Examples 2 to 11 Various evaluations were performed in the same manner as in Example 1 except that the aqueous solutions S2 to S11 in Table 1 were used instead of the aqueous solution S1. The results are shown in Table 1. The outline of the surfactant contained in each aqueous solution is shown below. In addition, the critical micelle concentration (CMC) of each surfactant was calculated according to the above-mentioned method using a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd.). Based on the CMC of each surfactant, the concentration of the surfactant in each aqueous solution is determined by how many times the concentration of the surfactant contained in each aqueous solution is compared with the CMC of the surfactant in Table 1. Shown in the column.
- CMC critical micelle concentration
- Water decomposition device 10 Container 20 Base material with photocatalyst 22 Base material 24 Photocatalyst S aqueous solution L Optical 100 Water decomposition device 110 Reaction container 120 Base material with photocatalyst 200 Closed circulation reaction system for automatic double photocatalyst 210 Pressure gauge 220 Circulation pump 230 Vacuum Pump 240 Piping 300 Xenon lamp 400 Gas chromatograph 500 Gas generation measurement system S1 Aqueous solution L1 Light
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Abstract
The present invention addresses the problem of providing a water-splitting device providing an increase in the initial amount of gas generated, and a method for producing gas. The water-splitting device according to the present invention comprises: a container containing a surfactant-containing aqueous solution; and a photocatalyst-coated substrate immersed in the aqueous solution and having a substrate and a photocatalyst fixed on the substrate, or a photocatalyst fixed on an inner wall surface of the container. Gas is generated from the photocatalyst by irradiation of the photocatalyst with light.
Description
本発明は、水分解装置および気体の製造方法に関する。
The present invention relates to a water splitting device and a method for producing a gas.
炭酸ガス排出削減、エネルギーのクリーン化の点から、太陽エネルギーを利用して、光触媒により水を分解して、水素および酸素を製造する技術に注目が集まっている。
例えば、特許文献１には、基材と、基材上に固定された光触媒とを有する光触媒付き基材を水中に配置し、光触媒付き基材に光を照射することによって水を分解して、水素および酸素の少なくとも一方を製造する方法が開示されている。 From the viewpoint of reducing carbon dioxide emissions and cleaning up energy, attention is focused on the technology of producing hydrogen and oxygen by decomposing water with a photocatalyst using solar energy.
For example, in Patent Document 1, a base material with a photocatalyst having a base material and a photocatalyst fixed on the base material is placed in water, and the base material with a photocatalyst is irradiated with light to decompose water. Methods for producing at least one of hydrogen and oxygen are disclosed.
例えば、特許文献１には、基材と、基材上に固定された光触媒とを有する光触媒付き基材を水中に配置し、光触媒付き基材に光を照射することによって水を分解して、水素および酸素の少なくとも一方を製造する方法が開示されている。 From the viewpoint of reducing carbon dioxide emissions and cleaning up energy, attention is focused on the technology of producing hydrogen and oxygen by decomposing water with a photocatalyst using solar energy.
For example, in Patent Document 1, a base material with a photocatalyst having a base material and a photocatalyst fixed on the base material is placed in water, and the base material with a photocatalyst is irradiated with light to decompose water. Methods for producing at least one of hydrogen and oxygen are disclosed.
近年、水分解装置を用いた水分解において、気体発生量のさらなる増加が求められている。本発明者らが、特許文献１の記載を参考にして、光触媒層付き基材を水中に浸漬させて水分解を実施したところ、初期の気体発生量が不十分となる場合があり、改善の余地があることを明らかとした。
In recent years, in water decomposition using a water decomposition device, further increase in the amount of gas generated is required. When the present inventors carried out water decomposition by immersing a base material with a photocatalyst layer in water with reference to the description in Patent Document 1, the initial amount of gas generated may be insufficient, which is an improvement. It became clear that there was room.
そこで、本発明は、初期の気体発生量に優れた水分解装置および気体の製造方法の提供を課題とする。
Therefore, an object of the present invention is to provide a water splitting device having an excellent initial amount of gas generated and a method for producing gas.
本発明者らは、上記課題を解決すべく鋭意検討した結果、界面活性剤を含む水溶液が収容された容器と、上記水溶液中に浸漬された光触媒付き基材または上記容器の内壁面上に固定された光触媒と、を有する水分解装置を用いて水分解を実施したところ、初期の気体発生量に優れることを見出した。
As a result of diligent studies to solve the above problems, the present inventors fixed the container containing the aqueous solution containing the surfactant on the photocatalytic substrate or the inner wall surface of the container immersed in the aqueous solution. When water splitting was carried out using a water splitting device having the photocatalyst, it was found that the initial amount of gas generated was excellent.
［１］
界面活性剤を含む水溶液が収容された容器と、
上記水溶液中に浸漬されており、基材および上記基材上に固定された光触媒を有する光触媒付き基材、または、上記容器の内壁面上に固定された光触媒と、を有し、
上記光触媒に光を照射することによって、上記光触媒から気体を発生させる、水分解装置。
［２］
サイクリックボルタンメトリー法によって上記水溶液の酸化ピーク電位を求めた場合、上記水溶液の酸化ピーク電位が、１．０Ｖ ｖｓ．ＲＨＥ以上である、［１］に記載の水分解装置。
［３］
上記界面活性剤が、芳香環を有しない、［１］または［２］に記載の水分解装置。
［４］
上記界面活性剤が、ヒドロキシ基、アルコキシ基、および、エーテル結合を有しない、［１］～［３］のいずれかに記載の水分解装置。
［５］
上記界面活性剤が後述の式Ｉで表される化合物を含む、［１］～［４］のいずれかに記載の水分解装置。
後述の式Ｉ中、Ｒ１は炭素数４～２０のアルキル基であり、Ｒ２、Ｒ３およびＲ４はそれぞれ独立にアルキル基であり、Ｘ－はハロゲン化物イオンまたは水酸化物イオンである。ただし、Ｒ２、Ｒ３およびＲ４におけるアルキル基の炭素数はいずれも、Ｒ１のアルキル基の炭素数以下である。
［６］
上記光触媒が、酸化物、酸窒化物、窒化物およびカルコゲナイド化合物からなる群から選択される少なくとも一種の光触媒化合物を含み、
上記光触媒化合物が、Ｓｒ、Ｎａ、Ｍｇ、Ａｌ、Ｓｉ、Ｃａ、Ｔｉ、Ｖ、Ｆｅ、Ｃｕ、Ｚｎ、Ｇａ、Ｙ、Ｚｒ、Ｎｂ、Ａｇ、Ｉｎ、Ｓｎ、Ｂａ、Ｌａ、Ｔａ、ＷおよびＢｉからなる群より選択される少なくとも１種の元素を含む、［１］～［５］のいずれかに記載の水分解装置。
［７］
上記光触媒が、水素発生用光触媒化合物および酸素発生用光触媒化合物の両方を含む、［１］～［６］のいずれかに記載の水分解装置。
［８］
上記光触媒が、Ｎａ、Ａｌ、Ｃｒ、Ｎｉ、Ｒｈ、ＳｂおよびＴａからなる群から選択される少なくとも１種の元素をドープしたＳｒＴｉＯ３を含む、［１］～［７］のいずれかに記載の水分解装置。
［９］
［１］～［８］のいずれかに記載の水分解装置を用いた気体の製造方法であって、
上記水分解装置が有する光触媒に光を照射することによって、上記光触媒の表面から気体を発生させる、気体の製造方法。 [1]
A container containing an aqueous solution containing a surfactant,
It has a base material and a photocatalyst-attached base material having a photocatalyst fixed on the base material, or a photocatalyst fixed on the inner wall surface of the container, which is immersed in the aqueous solution.
A water decomposition device that generates gas from the photocatalyst by irradiating the photocatalyst with light.
[2]
When the oxidation peak potential of the aqueous solution was determined by the cyclic voltammetry method, the oxidation peak potential of the aqueous solution was 1.0 V vs. The water splitting apparatus according to [1], which is RHE or higher.
[3]
The water splitting apparatus according to [1] or [2], wherein the surfactant does not have an aromatic ring.
[4]
The water splitting apparatus according to any one of [1] to [3], wherein the surfactant does not have a hydroxy group, an alkoxy group, or an ether bond.
[5]
The water splitting apparatus according to any one of [1] to [4], wherein the surfactant contains a compound represented by the formula I described later.
In the formula I described later, R 1 is an alkyl group having 4 to 20 carbon atoms, R 2 , R 3 and R 4 are independently alkyl groups, and X − is a halide ion or a hydroxide ion. .. However, the carbon number of the alkyl group in R2 , R3 and R4 is less than or equal to the carbon number of the alkyl group of R1 .
[6]
The photocatalyst comprises at least one photocatalytic compound selected from the group consisting of oxides, oxynitrides, nitrides and chalcogenide compounds.
The photocatalyst compounds are Sr, Na, Mg, Al, Si, Ca, Ti, V, Fe, Cu, Zn, Ga, Y, Zr, Nb, Ag, In, Sn, Ba, La, Ta, W and Bi. The water splitting apparatus according to any one of [1] to [5], which comprises at least one element selected from the group consisting of.
[7]
The water splitting apparatus according to any one of [1] to [6], wherein the photocatalyst contains both a photocatalyst compound for hydrogen generation and a photocatalyst compound for oxygen generation.
[8]
6. The photocatalyst according to any of [1] to [7], wherein the photocatalyst comprises SrTiO 3 doped with at least one element selected from the group consisting of Na, Al, Cr, Ni, Rh, Sb and Ta. Water decomposition device.
[9]
A method for producing a gas using the water splitting apparatus according to any one of [1] to [8].
A method for producing a gas, in which a gas is generated from the surface of the photocatalyst by irradiating the photocatalyst of the water splitting device with light.
界面活性剤を含む水溶液が収容された容器と、
上記水溶液中に浸漬されており、基材および上記基材上に固定された光触媒を有する光触媒付き基材、または、上記容器の内壁面上に固定された光触媒と、を有し、
上記光触媒に光を照射することによって、上記光触媒から気体を発生させる、水分解装置。
［２］
サイクリックボルタンメトリー法によって上記水溶液の酸化ピーク電位を求めた場合、上記水溶液の酸化ピーク電位が、１．０Ｖ ｖｓ．ＲＨＥ以上である、［１］に記載の水分解装置。
［３］
上記界面活性剤が、芳香環を有しない、［１］または［２］に記載の水分解装置。
［４］
上記界面活性剤が、ヒドロキシ基、アルコキシ基、および、エーテル結合を有しない、［１］～［３］のいずれかに記載の水分解装置。
［５］
上記界面活性剤が後述の式Ｉで表される化合物を含む、［１］～［４］のいずれかに記載の水分解装置。
後述の式Ｉ中、Ｒ１は炭素数４～２０のアルキル基であり、Ｒ２、Ｒ３およびＲ４はそれぞれ独立にアルキル基であり、Ｘ－はハロゲン化物イオンまたは水酸化物イオンである。ただし、Ｒ２、Ｒ３およびＲ４におけるアルキル基の炭素数はいずれも、Ｒ１のアルキル基の炭素数以下である。
［６］
上記光触媒が、酸化物、酸窒化物、窒化物およびカルコゲナイド化合物からなる群から選択される少なくとも一種の光触媒化合物を含み、
上記光触媒化合物が、Ｓｒ、Ｎａ、Ｍｇ、Ａｌ、Ｓｉ、Ｃａ、Ｔｉ、Ｖ、Ｆｅ、Ｃｕ、Ｚｎ、Ｇａ、Ｙ、Ｚｒ、Ｎｂ、Ａｇ、Ｉｎ、Ｓｎ、Ｂａ、Ｌａ、Ｔａ、ＷおよびＢｉからなる群より選択される少なくとも１種の元素を含む、［１］～［５］のいずれかに記載の水分解装置。
［７］
上記光触媒が、水素発生用光触媒化合物および酸素発生用光触媒化合物の両方を含む、［１］～［６］のいずれかに記載の水分解装置。
［８］
上記光触媒が、Ｎａ、Ａｌ、Ｃｒ、Ｎｉ、Ｒｈ、ＳｂおよびＴａからなる群から選択される少なくとも１種の元素をドープしたＳｒＴｉＯ３を含む、［１］～［７］のいずれかに記載の水分解装置。
［９］
［１］～［８］のいずれかに記載の水分解装置を用いた気体の製造方法であって、
上記水分解装置が有する光触媒に光を照射することによって、上記光触媒の表面から気体を発生させる、気体の製造方法。 [1]
A container containing an aqueous solution containing a surfactant,
It has a base material and a photocatalyst-attached base material having a photocatalyst fixed on the base material, or a photocatalyst fixed on the inner wall surface of the container, which is immersed in the aqueous solution.
A water decomposition device that generates gas from the photocatalyst by irradiating the photocatalyst with light.
[2]
When the oxidation peak potential of the aqueous solution was determined by the cyclic voltammetry method, the oxidation peak potential of the aqueous solution was 1.0 V vs. The water splitting apparatus according to [1], which is RHE or higher.
[3]
The water splitting apparatus according to [1] or [2], wherein the surfactant does not have an aromatic ring.
[4]
The water splitting apparatus according to any one of [1] to [3], wherein the surfactant does not have a hydroxy group, an alkoxy group, or an ether bond.
[5]
The water splitting apparatus according to any one of [1] to [4], wherein the surfactant contains a compound represented by the formula I described later.
In the formula I described later, R 1 is an alkyl group having 4 to 20 carbon atoms, R 2 , R 3 and R 4 are independently alkyl groups, and X − is a halide ion or a hydroxide ion. .. However, the carbon number of the alkyl group in R2 , R3 and R4 is less than or equal to the carbon number of the alkyl group of R1 .
[6]
The photocatalyst comprises at least one photocatalytic compound selected from the group consisting of oxides, oxynitrides, nitrides and chalcogenide compounds.
The photocatalyst compounds are Sr, Na, Mg, Al, Si, Ca, Ti, V, Fe, Cu, Zn, Ga, Y, Zr, Nb, Ag, In, Sn, Ba, La, Ta, W and Bi. The water splitting apparatus according to any one of [1] to [5], which comprises at least one element selected from the group consisting of.
[7]
The water splitting apparatus according to any one of [1] to [6], wherein the photocatalyst contains both a photocatalyst compound for hydrogen generation and a photocatalyst compound for oxygen generation.
[8]
6. The photocatalyst according to any of [1] to [7], wherein the photocatalyst comprises SrTiO 3 doped with at least one element selected from the group consisting of Na, Al, Cr, Ni, Rh, Sb and Ta. Water decomposition device.
[9]
A method for producing a gas using the water splitting apparatus according to any one of [1] to [8].
A method for producing a gas, in which a gas is generated from the surface of the photocatalyst by irradiating the photocatalyst of the water splitting device with light.
本発明によれば、初期の気体発生量に優れた水分解装置および気体の製造方法を提供できる。
According to the present invention, it is possible to provide a water splitting device having an excellent initial amount of gas generated and a method for producing gas.
以下、本発明について説明する。
以下に記載する構成要件の説明は、本発明の代表的な実施態様に基づいてなされることがあるが、本発明はそのような実施態様に限定されるものではない。
なお、本発明において「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値および上限値として含む範囲を意味する。
本発明において、可視光とは、電磁波のうちヒトの目で見える波長の光であり、具体的には３８０～７８０ｎｍの波長域の光を示す。 Hereinafter, the present invention will be described.
The description of the constituent elements described below may be based on the representative embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present invention, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
In the present invention, the visible light is light having a wavelength visible to the human eye among electromagnetic waves, and specifically, light in a wavelength range of 380 to 780 nm.
以下に記載する構成要件の説明は、本発明の代表的な実施態様に基づいてなされることがあるが、本発明はそのような実施態様に限定されるものではない。
なお、本発明において「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値および上限値として含む範囲を意味する。
本発明において、可視光とは、電磁波のうちヒトの目で見える波長の光であり、具体的には３８０～７８０ｎｍの波長域の光を示す。 Hereinafter, the present invention will be described.
The description of the constituent elements described below may be based on the representative embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present invention, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
In the present invention, the visible light is light having a wavelength visible to the human eye among electromagnetic waves, and specifically, light in a wavelength range of 380 to 780 nm.
［水分解装置］
本発明の水分解装置は、界面活性剤を含む水溶液が収容された容器と、上記水溶液中に浸漬されており、基材および上記基材上に固定された光触媒を有する光触媒付き基材、または、上記容器の内壁面上に固定された光触媒と、を有する。
本発明の水分解装置は、初期の気体発生量に優れる。この理由の詳細は明らかになっていないが、概ね以下の理由によるものと推測される。 [Water decomposition device]
The water splitting apparatus of the present invention is a container containing an aqueous solution containing a surfactant, a base material with a photocatalyst having a base material and a photocatalyst fixed on the base material, or a base material having a photocatalyst, which is immersed in the aqueous solution. , A photocatalyst fixed on the inner wall surface of the container.
The water splitting apparatus of the present invention is excellent in the initial amount of gas generated. The details of this reason have not been clarified, but it is presumed that it is due to the following reasons.
本発明の水分解装置は、界面活性剤を含む水溶液が収容された容器と、上記水溶液中に浸漬されており、基材および上記基材上に固定された光触媒を有する光触媒付き基材、または、上記容器の内壁面上に固定された光触媒と、を有する。
本発明の水分解装置は、初期の気体発生量に優れる。この理由の詳細は明らかになっていないが、概ね以下の理由によるものと推測される。 [Water decomposition device]
The water splitting apparatus of the present invention is a container containing an aqueous solution containing a surfactant, a base material with a photocatalyst having a base material and a photocatalyst fixed on the base material, or a base material having a photocatalyst, which is immersed in the aqueous solution. , A photocatalyst fixed on the inner wall surface of the container.
The water splitting apparatus of the present invention is excellent in the initial amount of gas generated. The details of this reason have not been clarified, but it is presumed that it is due to the following reasons.
水分解装置としては、例えば、水素発生反応と酸素発生反応が同一粒子上で起こる光触媒を基材上に固定化した光触媒付き基材、水素発生反応と酸素発生反応が同一粒子上で起こる光触媒を容器の内壁面上に固定化した光触媒、水素発生用光触媒化合物と酸素発生用光触媒化合物が基材上に固定化した光触媒付き基材、および、水素発生用光触媒化合物と酸素発生用光触媒化合物が内壁面上に固定化した光触媒、を有する態様が挙げられる。
このような光触媒は、水素発生反応点と酸素発生反応点が近接する為、光触媒表面での水分解による水素および酸素の発生のみならず、水素と酸素の逆反応（２Ｈ２＋Ｏ２→２Ｈ２Ｏ）が同時に進行することによる気体発生量が低下する場合がある。
特許文献１では、光触媒付き基材に粒子状の親水性無機材料を添加することで、光触媒付き基材への気泡付着を防止し、水素および酸素の拡散が促進されて反応効率が向上することが開示されている。しかしながらこの方法では、粒子状の親水性無機材料のばらつきから、光触媒付き基材の表面に疎水性の部分が生じ、この部分に気泡が付着して気泡離脱回数が減り、気体の拡散が阻害され、気体発生量が低下する問題を有していた。
本発明者らは、光触媒反応の原料となる水に界面活性剤を添加した水溶液を用いることにより、水の表面張力が低下し、疎水部分のある光触媒でも、気泡の付着なく速やかに光触媒表面から離脱できる為、気泡離脱回数が増加して、気体発生量の低下が抑制できることを見出した。
すなわち、界面活性剤の効果により、光触媒表面で発生した水素と酸素が気泡として速やかに光触媒表面から離脱するため、上記逆反応を抑制でき、初期の気体発生量が多くなったと推測される。 Examples of the water splitting device include a photocatalyst-equipped substrate in which a photocatalyst in which a hydrogen generation reaction and an oxygen generation reaction occur on the same particle is immobilized on the substrate, and a photocatalyst in which a hydrogen generation reaction and an oxygen generation reaction occur on the same particle. The photocatalyst immobilized on the inner wall surface of the container, the photocatalyst-equipped substrate in which the photocatalyst compound for hydrogen generation and the photocatalyst compound for oxygen generation are immobilized on the substrate, and the photocatalyst compound for hydrogen generation and the photocatalyst compound for oxygen generation are inside. An embodiment having a photocatalyst immobilized on a wall surface can be mentioned.
In such a photocatalyst, since the hydrogen evolution reaction point and the oxygen evolution reaction point are close to each other, not only hydrogen and oxygen are generated by water decomposition on the surface of the photocatalyst, but also the reverse reaction between hydrogen and oxygen (2H 2 + O 2 → 2H 2 ). The amount of gas generated may decrease due to the simultaneous progress of O).
In Patent Document 1, by adding a particulate hydrophilic inorganic material to the photocatalytic substrate, the adhesion of bubbles to the photocatalyst substrate is prevented, the diffusion of hydrogen and oxygen is promoted, and the reaction efficiency is improved. Is disclosed. However, in this method, due to the variation in the particulate hydrophilic inorganic material, a hydrophobic portion is generated on the surface of the photocatalytic substrate, bubbles adhere to this portion, the number of times of bubble separation is reduced, and the diffusion of gas is hindered. , There was a problem that the amount of gas generated was reduced.
By using an aqueous solution in which a surfactant is added to water, which is a raw material for a photocatalytic reaction, the present inventors reduce the surface tension of water, and even if the photocatalyst has a hydrophobic portion, the surface of the photocatalyst can be quickly removed without bubbles. It was found that since the bubbles can be separated, the number of bubbles released can be increased and the decrease in the amount of gas generated can be suppressed.
That is, it is presumed that due to the effect of the surfactant, hydrogen and oxygen generated on the surface of the photocatalyst are rapidly separated from the surface of the photocatalyst as bubbles, so that the reverse reaction can be suppressed and the initial amount of gas generated is increased.
このような光触媒は、水素発生反応点と酸素発生反応点が近接する為、光触媒表面での水分解による水素および酸素の発生のみならず、水素と酸素の逆反応（２Ｈ２＋Ｏ２→２Ｈ２Ｏ）が同時に進行することによる気体発生量が低下する場合がある。
特許文献１では、光触媒付き基材に粒子状の親水性無機材料を添加することで、光触媒付き基材への気泡付着を防止し、水素および酸素の拡散が促進されて反応効率が向上することが開示されている。しかしながらこの方法では、粒子状の親水性無機材料のばらつきから、光触媒付き基材の表面に疎水性の部分が生じ、この部分に気泡が付着して気泡離脱回数が減り、気体の拡散が阻害され、気体発生量が低下する問題を有していた。
本発明者らは、光触媒反応の原料となる水に界面活性剤を添加した水溶液を用いることにより、水の表面張力が低下し、疎水部分のある光触媒でも、気泡の付着なく速やかに光触媒表面から離脱できる為、気泡離脱回数が増加して、気体発生量の低下が抑制できることを見出した。
すなわち、界面活性剤の効果により、光触媒表面で発生した水素と酸素が気泡として速やかに光触媒表面から離脱するため、上記逆反応を抑制でき、初期の気体発生量が多くなったと推測される。 Examples of the water splitting device include a photocatalyst-equipped substrate in which a photocatalyst in which a hydrogen generation reaction and an oxygen generation reaction occur on the same particle is immobilized on the substrate, and a photocatalyst in which a hydrogen generation reaction and an oxygen generation reaction occur on the same particle. The photocatalyst immobilized on the inner wall surface of the container, the photocatalyst-equipped substrate in which the photocatalyst compound for hydrogen generation and the photocatalyst compound for oxygen generation are immobilized on the substrate, and the photocatalyst compound for hydrogen generation and the photocatalyst compound for oxygen generation are inside. An embodiment having a photocatalyst immobilized on a wall surface can be mentioned.
In such a photocatalyst, since the hydrogen evolution reaction point and the oxygen evolution reaction point are close to each other, not only hydrogen and oxygen are generated by water decomposition on the surface of the photocatalyst, but also the reverse reaction between hydrogen and oxygen (2H 2 + O 2 → 2H 2 ). The amount of gas generated may decrease due to the simultaneous progress of O).
In Patent Document 1, by adding a particulate hydrophilic inorganic material to the photocatalytic substrate, the adhesion of bubbles to the photocatalyst substrate is prevented, the diffusion of hydrogen and oxygen is promoted, and the reaction efficiency is improved. Is disclosed. However, in this method, due to the variation in the particulate hydrophilic inorganic material, a hydrophobic portion is generated on the surface of the photocatalytic substrate, bubbles adhere to this portion, the number of times of bubble separation is reduced, and the diffusion of gas is hindered. , There was a problem that the amount of gas generated was reduced.
By using an aqueous solution in which a surfactant is added to water, which is a raw material for a photocatalytic reaction, the present inventors reduce the surface tension of water, and even if the photocatalyst has a hydrophobic portion, the surface of the photocatalyst can be quickly removed without bubbles. It was found that since the bubbles can be separated, the number of bubbles released can be increased and the decrease in the amount of gas generated can be suppressed.
That is, it is presumed that due to the effect of the surfactant, hydrogen and oxygen generated on the surface of the photocatalyst are rapidly separated from the surface of the photocatalyst as bubbles, so that the reverse reaction can be suppressed and the initial amount of gas generated is increased.
以下において、本発明の水分解装置の構成について、図面を参照しながら説明する。
図１は、本発明の水分解装置の一例である水分解装置１を模式的に示す端面図である。図１に示すように、水分解装置１は、界面活性剤を含む水溶液Ｓで満たされた容器１０と、容器１０内に配置された光触媒付き基材２０と、を有する。光触媒付き基材２０は、基材２２と、基材２２上に固定された光触媒２４と、を有する。光触媒付き基材２０は、容器２０内において、光触媒２４が光Ｌを受光できる位置に配置されている。
水分解装置１は、光Ｌの照射によって、光触媒２４の表面から気体を発生させる装置である。具体的には、光触媒２４に対する光Ｌの照射によって、光触媒２４の表面で水の分解が起こり、酸素および水素の少なくとも一方が発生する。
照射される光Ｌとしては、太陽光等の可視光、紫外光または赤外光等が利用でき、その中でも、その量が無尽蔵である太陽光が好ましい。 Hereinafter, the configuration of the water splitting apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is an end view schematically showing a water splitting device 1 which is an example of the water splitting device of the present invention. As shown in FIG. 1, the water splitting device 1 has acontainer 10 filled with an aqueous solution S containing a surfactant, and a photocatalytic substrate 20 arranged in the container 10. The photocatalyst-attached base material 20 has a base material 22 and a photocatalyst 24 fixed on the base material 22. The base material 20 with a photocatalyst 20 is arranged in the container 20 at a position where the photocatalyst 24 can receive light L.
The water decomposition device 1 is a device that generates a gas from the surface of thephotocatalyst 24 by irradiation with light L. Specifically, irradiation of the photocatalyst 24 with light L causes decomposition of water on the surface of the photocatalyst 24, and at least one of oxygen and hydrogen is generated.
As the light L to be irradiated, visible light such as sunlight, ultraviolet light, infrared light and the like can be used, and among them, sunlight whose amount is inexhaustible is preferable.
図１は、本発明の水分解装置の一例である水分解装置１を模式的に示す端面図である。図１に示すように、水分解装置１は、界面活性剤を含む水溶液Ｓで満たされた容器１０と、容器１０内に配置された光触媒付き基材２０と、を有する。光触媒付き基材２０は、基材２２と、基材２２上に固定された光触媒２４と、を有する。光触媒付き基材２０は、容器２０内において、光触媒２４が光Ｌを受光できる位置に配置されている。
水分解装置１は、光Ｌの照射によって、光触媒２４の表面から気体を発生させる装置である。具体的には、光触媒２４に対する光Ｌの照射によって、光触媒２４の表面で水の分解が起こり、酸素および水素の少なくとも一方が発生する。
照射される光Ｌとしては、太陽光等の可視光、紫外光または赤外光等が利用でき、その中でも、その量が無尽蔵である太陽光が好ましい。 Hereinafter, the configuration of the water splitting apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is an end view schematically showing a water splitting device 1 which is an example of the water splitting device of the present invention. As shown in FIG. 1, the water splitting device 1 has a
The water decomposition device 1 is a device that generates a gas from the surface of the
As the light L to be irradiated, visible light such as sunlight, ultraviolet light, infrared light and the like can be used, and among them, sunlight whose amount is inexhaustible is preferable.
＜容器＞
容器１０は、水溶液Ｓを収容し、かつ、光触媒付き基材２０の設置に用いる容器である。容器１０の形状は、水溶液Ｓを収容でき、かつ、光触媒付き基材２０を設置できるのであれば、特に限定されない。
容器１０を構成する材料の具体例としては、耐腐食性に優れた材料が好ましく、ポリアクリレート、ポリメタクリレート、ポリカーボネート、ポリプロピレン、ポリエチレン、ポリスチレン、ポリエチレンテレフタレート、ポリエチレンナフタレート、ガラス、金属等が挙げられる。
容器１０の内壁面は、光触媒２４の表面から発生した気体が気泡として付着することにより、気体の回収や水溶液Ｓの供給を阻害すること、ならびに光Ｌを散乱させて光触媒２４表面での光量が低下することなどを防ぐために、親水化処理を施すことが好ましい。また、容器１０を構成する材料がガラスの場合は、親水化処理が不要なため、好ましく用いられる。 <Container>
Thecontainer 10 is a container that contains the aqueous solution S and is used for installing the base material 20 with a photocatalyst. The shape of the container 10 is not particularly limited as long as it can accommodate the aqueous solution S and the base material 20 with a photocatalyst can be installed.
Specific examples of the material constituting thecontainer 10 are preferably a material having excellent corrosion resistance, and examples thereof include polyacrylate, polymethacrylate, polycarbonate, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polyethylene naphthalate, glass, and metal. ..
Gas generated from the surface of thephotocatalyst 24 adheres to the inner wall surface of the container 10 as bubbles, which hinders the recovery of the gas and the supply of the aqueous solution S, and scatters the light L to increase the amount of light on the surface of the photocatalyst 24. It is preferable to perform a hydrophilization treatment in order to prevent the decrease. Further, when the material constituting the container 10 is glass, it is preferably used because it does not require a hydrophilization treatment.
容器１０は、水溶液Ｓを収容し、かつ、光触媒付き基材２０の設置に用いる容器である。容器１０の形状は、水溶液Ｓを収容でき、かつ、光触媒付き基材２０を設置できるのであれば、特に限定されない。
容器１０を構成する材料の具体例としては、耐腐食性に優れた材料が好ましく、ポリアクリレート、ポリメタクリレート、ポリカーボネート、ポリプロピレン、ポリエチレン、ポリスチレン、ポリエチレンテレフタレート、ポリエチレンナフタレート、ガラス、金属等が挙げられる。
容器１０の内壁面は、光触媒２４の表面から発生した気体が気泡として付着することにより、気体の回収や水溶液Ｓの供給を阻害すること、ならびに光Ｌを散乱させて光触媒２４表面での光量が低下することなどを防ぐために、親水化処理を施すことが好ましい。また、容器１０を構成する材料がガラスの場合は、親水化処理が不要なため、好ましく用いられる。 <Container>
The
Specific examples of the material constituting the
Gas generated from the surface of the
＜水溶液＞
図１に示すように、水溶液Ｓは、界面活性剤を水に溶解させた水溶液であり、容器１０内に収容されている。水溶液Ｓは、水分解に使用される原料である。
界面活性剤の具体例としては、カチオン性界面活性剤、アニオン性界面活性剤および両性界面活性剤等のイオン性の界面活性剤、ならびに、ノニオン性界面活性剤等が挙げられる。 <Aqueous solution>
As shown in FIG. 1, the aqueous solution S is an aqueous solution in which a surfactant is dissolved in water, and is contained in acontainer 10. The aqueous solution S is a raw material used for water decomposition.
Specific examples of the surfactant include ionic surfactants such as cationic surfactants, anionic surfactants and amphoteric surfactants, and nonionic surfactants.
図１に示すように、水溶液Ｓは、界面活性剤を水に溶解させた水溶液であり、容器１０内に収容されている。水溶液Ｓは、水分解に使用される原料である。
界面活性剤の具体例としては、カチオン性界面活性剤、アニオン性界面活性剤および両性界面活性剤等のイオン性の界面活性剤、ならびに、ノニオン性界面活性剤等が挙げられる。 <Aqueous solution>
As shown in FIG. 1, the aqueous solution S is an aqueous solution in which a surfactant is dissolved in water, and is contained in a
Specific examples of the surfactant include ionic surfactants such as cationic surfactants, anionic surfactants and amphoteric surfactants, and nonionic surfactants.
カチオン性界面活性剤の具体例としては、脂肪族アミン塩、脂肪族４級アンモニウム塩、芳香族４級アンモニウム塩、塩化ベンザルコニウム塩、塩化ベンゼトニウム、ピリジニウム塩およびイミダゾリニウム塩等が挙げられる。
アニオン性界面活性剤の具体例としては、カルボン酸塩、スルホン酸塩（例えば、アルキルスルホン酸塩、アルキルベンゼンスルホン酸塩）、硫酸エステル塩、および、リン酸エステル塩等が挙げられる。
両性界面活性剤の具体例としては、カルボキシベタイン型、スルホベタイン型、アミノカルボン酸塩、イミダゾリニウムベタイン、レシチン、および、アルキルアミンオキサイド等が挙げられる。
ノニオン性界面活性剤の具体例としては、ポリオキシエチレン高級アルキルエーテル類、ポリオキシエチレン高級アルキルフェニルエーテル類、ポリオキシエチレングリコールの高級脂肪酸ジエステル類、シリコーン系界面活性剤、および、フッ素系界面活性剤等が挙げられる。炭素－水素結合の一部が炭素－フッ素結合に置換されたフッ素系界面活性剤は、安定性に優れるため好ましく用いられる。
界面活性剤は、１種単独で用いてもよく、２種以上を併用してもよい。 Specific examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, aromatic quaternary ammonium salts, benzalkonium chloride salt, benzethonium chloride, pyridinium salt, imidazolinium salt and the like. ..
Specific examples of the anionic surfactant include carboxylates, sulfonates (eg, alkyl sulfonates, alkylbenzene sulfonates), sulfate ester salts, phosphate ester salts and the like.
Specific examples of the amphoteric tenside include carboxybetaine type, sulfobetaine type, aminocarboxylate, imidazolinium betaine, lecithin, alkylamine oxide and the like.
Specific examples of nonionic surfactants include polyoxyethylene higher alkyl ethers, polyoxyethylene higher alkylphenyl ethers, polyoxyethylene glycol higher fatty acid diesters, silicone-based surfactants, and fluorine-based surfactants. Agents and the like can be mentioned. A fluorine-based surfactant in which a part of the carbon-hydrogen bond is replaced with a carbon-fluorine bond is preferably used because of its excellent stability.
The surfactant may be used alone or in combination of two or more.
アニオン性界面活性剤の具体例としては、カルボン酸塩、スルホン酸塩（例えば、アルキルスルホン酸塩、アルキルベンゼンスルホン酸塩）、硫酸エステル塩、および、リン酸エステル塩等が挙げられる。
両性界面活性剤の具体例としては、カルボキシベタイン型、スルホベタイン型、アミノカルボン酸塩、イミダゾリニウムベタイン、レシチン、および、アルキルアミンオキサイド等が挙げられる。
ノニオン性界面活性剤の具体例としては、ポリオキシエチレン高級アルキルエーテル類、ポリオキシエチレン高級アルキルフェニルエーテル類、ポリオキシエチレングリコールの高級脂肪酸ジエステル類、シリコーン系界面活性剤、および、フッ素系界面活性剤等が挙げられる。炭素－水素結合の一部が炭素－フッ素結合に置換されたフッ素系界面活性剤は、安定性に優れるため好ましく用いられる。
界面活性剤は、１種単独で用いてもよく、２種以上を併用してもよい。 Specific examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, aromatic quaternary ammonium salts, benzalkonium chloride salt, benzethonium chloride, pyridinium salt, imidazolinium salt and the like. ..
Specific examples of the anionic surfactant include carboxylates, sulfonates (eg, alkyl sulfonates, alkylbenzene sulfonates), sulfate ester salts, phosphate ester salts and the like.
Specific examples of the amphoteric tenside include carboxybetaine type, sulfobetaine type, aminocarboxylate, imidazolinium betaine, lecithin, alkylamine oxide and the like.
Specific examples of nonionic surfactants include polyoxyethylene higher alkyl ethers, polyoxyethylene higher alkylphenyl ethers, polyoxyethylene glycol higher fatty acid diesters, silicone-based surfactants, and fluorine-based surfactants. Agents and the like can be mentioned. A fluorine-based surfactant in which a part of the carbon-hydrogen bond is replaced with a carbon-fluorine bond is preferably used because of its excellent stability.
The surfactant may be used alone or in combination of two or more.
界面活性剤は、光触媒表面で安定に存在できて、初期の気体発生量がより優れる点から、光触媒表面で酸化されやすいヒドロキシ基、アルコキシ基、および、エーテル結合を有しないことが好ましい。
It is preferable that the surfactant does not have a hydroxy group, an alkoxy group, and an ether bond that are easily oxidized on the photocatalyst surface because it can exist stably on the photocatalyst surface and the initial amount of gas generated is more excellent.
界面活性剤は、水分解反応中に安定に存在できて、初期の気体発生量が優れる点から、水分解の反応中間体として生成される活性酸素種により酸化されやすい芳香環（例えば、ベンゼン等の芳香族炭化水素環、ならびに、イミダゾール、ピラゾールおよびピリジン等の芳香族複素環）を有しないことが好ましい。
Aromatic rings (eg, benzene, etc.) that are easily oxidized by active oxygen species produced as reaction intermediates for water splitting, because the surfactant can exist stably during the water splitting reaction and the amount of initial gas generated is excellent. It is preferable not to have an aromatic hydrocarbon ring and an aromatic heterocycle such as imidazole, pyrazole and pyridine).
界面活性剤は、水素発生速度の経過値が優れる点（すなわち、光触媒に対して長時間光照射した場合において、水素発生速度の低下を抑制できる点）から、式Ｉで表される化合物を含むことが好ましく、式Ｉで表される化合物であることが特に好ましい。
The surfactant contains a compound represented by the formula I because the elapsed value of the hydrogen generation rate is excellent (that is, the decrease in the hydrogen generation rate can be suppressed when the photocatalyst is irradiated with light for a long time). It is preferable, and it is particularly preferable that the compound is represented by the formula I.
式Ｉ中、Ｒ１は炭素数４～２０のアルキル基である。
Ｒ１におけるアルキル基は、直鎖状、分岐状または環状であってもよい。
Ｒ１におけるアルキル基の炭素数は、４～２０であり、初期の気体発生量、および水素発生速度の経過値がより優れる点から、６～１８が好ましく、８～１６が特に好ましい。 In Formula I, R 1 is an alkyl group having 4 to 20 carbon atoms.
The alkyl group in R 1 may be linear, branched or cyclic.
The number of carbon atoms of the alkyl group in R1 is 4 to 20, and 6 to 18 is preferable, and 8 to 16 is particularly preferable, because the initial amount of gas generated and the elapsed value of the hydrogen generation rate are more excellent.
Ｒ１におけるアルキル基は、直鎖状、分岐状または環状であってもよい。
Ｒ１におけるアルキル基の炭素数は、４～２０であり、初期の気体発生量、および水素発生速度の経過値がより優れる点から、６～１８が好ましく、８～１６が特に好ましい。 In Formula I, R 1 is an alkyl group having 4 to 20 carbon atoms.
The alkyl group in R 1 may be linear, branched or cyclic.
The number of carbon atoms of the alkyl group in R1 is 4 to 20, and 6 to 18 is preferable, and 8 to 16 is particularly preferable, because the initial amount of gas generated and the elapsed value of the hydrogen generation rate are more excellent.
式Ｉ中、Ｒ２、Ｒ３およびＲ４はそれぞれ独立に、アルキル基である。ただし、Ｒ２、Ｒ３およびＲ４におけるアルキル基の炭素数はいずれも、Ｒ１のアルキル基の炭素数以下である。なお、Ｒ２、Ｒ３およびＲ４におけるアルキル基の炭素数の下限値は、１である。
Ｒ２～Ｒ４におけるアルキル基は、直鎖状、分岐状または環状であってもよい。
Ｒ２～Ｒ４は、同一であっても異なっていてもよい。 In Formula I, R 2 , R 3 and R 4 are independently alkyl groups. However, the carbon number of the alkyl group in R2 , R3 and R4 is less than or equal to the carbon number of the alkyl group of R1 . The lower limit of the number of carbon atoms of the alkyl group in R 2 , R 3 and R 4 is 1.
The alkyl groups in R2 to R4 may be linear, branched or cyclic.
R2 to R4 may be the same or different.
Ｒ２～Ｒ４におけるアルキル基は、直鎖状、分岐状または環状であってもよい。
Ｒ２～Ｒ４は、同一であっても異なっていてもよい。 In Formula I, R 2 , R 3 and R 4 are independently alkyl groups. However, the carbon number of the alkyl group in R2 , R3 and R4 is less than or equal to the carbon number of the alkyl group of R1 . The lower limit of the number of carbon atoms of the alkyl group in R 2 , R 3 and R 4 is 1.
The alkyl groups in R2 to R4 may be linear, branched or cyclic.
R2 to R4 may be the same or different.
Ｘ－は、ハロゲン化物イオンまたは水酸化物イオンである。Ｘ－は、水分解反応中での安定性に優れる点から、ハロゲン化物イオンが好ましく、Ｆ－、Ｃｌ－、または、Ｂｒ－がより好ましい。
X − is a halide ion or a hydroxide ion. For X − , a halide ion is preferable, and F − , Cl − , or Br − is more preferable because it is excellent in stability during a water splitting reaction.
サイクリックボルタンメトリー法によって水溶液の酸化ピーク電位を求めた場合、水溶液の酸化ピーク電位は、光触媒表面で界面活性剤分子が酸化されにくく安定に存在できて、初期の気体発生量が優れる点から、１．０Ｖ ｖｓ．ＲＨＥ以上であることが好ましく、１．３Ｖ ｖｓ．ＲＨＥ以上がより好ましく、１．６Ｖ ｖｓ．ＲＨＥ以上が特に好ましい。
なお、上記水溶液の酸化ピーク電位の上限値は、特に限定されないが、３．０Ｖ ｖｓ．ＲＨＥ以下が好ましい。
ここで、ＲＨＥは、reversible hydrogen electrode（可逆水素電極）の略である。水溶液の酸化ピーク電位は、後述する実施例欄に記載の方法によって測定できる。
なお、０．５Ｖ ｖｓ．ＲＨＥ未満に現れる酸化ピーク電位は、測定に使用する白金電極に由来する酸化ピーク電位であるため、０．５Ｖ ｖｓ．ＲＨＥ以上に現れる酸化ピーク電位が水溶液の酸化ピーク電位である。 When the oxidation peak potential of the aqueous solution is determined by the cyclic voltammetry method, the oxidation peak potential of the aqueous solution is 1 because the surfactant molecules are less likely to be oxidized on the surface of the photocatalyst and can exist stably, and the initial gas generation amount is excellent. .0V vs. It is preferably RHE or higher, and 1.3 V vs. RHE or higher is more preferable, 1.6 V vs. RHE or higher is particularly preferable.
The upper limit of the oxidation peak potential of the aqueous solution is not particularly limited, but is 3.0 V vs. RHE or less is preferable.
Here, RHE is an abbreviation for reversible hydrogen electrode. The oxidation peak potential of the aqueous solution can be measured by the method described in the Example column described later.
In addition, 0.5V vs. Since the oxidation peak potential appearing below RHE is the oxidation peak potential derived from the platinum electrode used for the measurement, 0.5 V vs. The oxidation peak potential that appears above RHE is the oxidation peak potential of the aqueous solution.
なお、上記水溶液の酸化ピーク電位の上限値は、特に限定されないが、３．０Ｖ ｖｓ．ＲＨＥ以下が好ましい。
ここで、ＲＨＥは、reversible hydrogen electrode（可逆水素電極）の略である。水溶液の酸化ピーク電位は、後述する実施例欄に記載の方法によって測定できる。
なお、０．５Ｖ ｖｓ．ＲＨＥ未満に現れる酸化ピーク電位は、測定に使用する白金電極に由来する酸化ピーク電位であるため、０．５Ｖ ｖｓ．ＲＨＥ以上に現れる酸化ピーク電位が水溶液の酸化ピーク電位である。 When the oxidation peak potential of the aqueous solution is determined by the cyclic voltammetry method, the oxidation peak potential of the aqueous solution is 1 because the surfactant molecules are less likely to be oxidized on the surface of the photocatalyst and can exist stably, and the initial gas generation amount is excellent. .0V vs. It is preferably RHE or higher, and 1.3 V vs. RHE or higher is more preferable, 1.6 V vs. RHE or higher is particularly preferable.
The upper limit of the oxidation peak potential of the aqueous solution is not particularly limited, but is 3.0 V vs. RHE or less is preferable.
Here, RHE is an abbreviation for reversible hydrogen electrode. The oxidation peak potential of the aqueous solution can be measured by the method described in the Example column described later.
In addition, 0.5V vs. Since the oxidation peak potential appearing below RHE is the oxidation peak potential derived from the platinum electrode used for the measurement, 0.5 V vs. The oxidation peak potential that appears above RHE is the oxidation peak potential of the aqueous solution.
本発明における水溶液の好適態様の一つとしては、芳香環を有しない界面活性剤を含み、かつ、水溶液の酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ以上である態様が挙げられる。これにより、初期の気体発生量により優れた水分解装置が得られる。
本発明における水溶液の好適態様の一つとしては、芳香環、ヒドロキシ基、アルコキシ基、および、エーテル結合を有しない界面活性剤を含み、かつ、水溶液の酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ以上である態様が挙げられる。これにより、水素発生速度に優れた水分解装置が得られる。
本発明における水溶液の好適態様の一つとしては、上記式Ｉを満たす界面活性剤を含む態様が挙げられる。これにより、水素発生速度の経過値に優れた水分解装置が得られる。 As one of the preferred embodiments of the aqueous solution in the present invention, a surfactant having no aromatic ring is contained, and the oxidation peak potential of the aqueous solution is 1.0 V vs. Examples thereof include RHE and above. As a result, an excellent water splitting device can be obtained due to the initial amount of gas generated.
One of the preferred embodiments of the aqueous solution in the present invention is a surfactant containing an aromatic ring, a hydroxy group, an alkoxy group, and an ether bond, and the oxidation peak potential of the aqueous solution is 1.0 V vs. Examples thereof include RHE and above. As a result, a water splitting device having an excellent hydrogen generation rate can be obtained.
One of the preferred embodiments of the aqueous solution in the present invention includes an embodiment containing a surfactant satisfying the above formula I. As a result, a water splitting device having an excellent elapsed value of the hydrogen generation rate can be obtained.
本発明における水溶液の好適態様の一つとしては、芳香環、ヒドロキシ基、アルコキシ基、および、エーテル結合を有しない界面活性剤を含み、かつ、水溶液の酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ以上である態様が挙げられる。これにより、水素発生速度に優れた水分解装置が得られる。
本発明における水溶液の好適態様の一つとしては、上記式Ｉを満たす界面活性剤を含む態様が挙げられる。これにより、水素発生速度の経過値に優れた水分解装置が得られる。 As one of the preferred embodiments of the aqueous solution in the present invention, a surfactant having no aromatic ring is contained, and the oxidation peak potential of the aqueous solution is 1.0 V vs. Examples thereof include RHE and above. As a result, an excellent water splitting device can be obtained due to the initial amount of gas generated.
One of the preferred embodiments of the aqueous solution in the present invention is a surfactant containing an aromatic ring, a hydroxy group, an alkoxy group, and an ether bond, and the oxidation peak potential of the aqueous solution is 1.0 V vs. Examples thereof include RHE and above. As a result, a water splitting device having an excellent hydrogen generation rate can be obtained.
One of the preferred embodiments of the aqueous solution in the present invention includes an embodiment containing a surfactant satisfying the above formula I. As a result, a water splitting device having an excellent elapsed value of the hydrogen generation rate can be obtained.
水溶液中の界面活性剤の濃度の下限値は、表面張力の低下により、光触媒表面から気泡が離脱しやすくなり、水分解で発生した気体の拡散が優れる点から、界面活性剤固有の臨界ミセル濃度（ＣＭＣ）の０．２５倍以上が好ましく、ＣＭＣの０．５倍以上がより好ましく、ＣＭＣの１倍以上が特に好ましい。
水溶液中の界面活性剤の濃度の上限値は、水溶液の白濁を避ける点から、ＣＭＣの２０倍以下が好ましく、ＣＭＣの１０倍以下がより好ましく、ＣＭＣの５倍以下が特に好ましい。
界面活性剤固有の臨界ミセル濃度（ＣＭＣ）は、例えば、表面張力計（協和界面科学社製）によって、界面活性剤の濃度を変化させて水の表面張力を測定し、界面活性剤濃度と表面張力のプロットにおける変曲点の濃度（界面活性剤濃度の増加による表面張力の低下が収まり、表面張力値が一定となる最も低い濃度）がＣＭＣ値として求められる。また、上記の表面張力法以外に、電気伝導法、色素法、蛍光法、粘度法によってもＣＭＣ値を得られる。更に、M. J. Rosen、J. T. Kunjappu編、Surfactants and interfacial phenomena、第４版、John Wiley & Sons社（２０１２年）などの文献に記載されている界面活性剤各種のＣＭＣ値を参照することもできる。 The lower limit of the concentration of the surfactant in the aqueous solution is the critical micelle concentration peculiar to the surfactant because the decrease in surface tension makes it easier for bubbles to separate from the surface of the photocatalyst and the diffusion of the gas generated by water splitting is excellent. 0.25 times or more of (CMC) is preferable, 0.5 times or more of CMC is more preferable, and 1 time or more of CMC is particularly preferable.
The upper limit of the concentration of the surfactant in the aqueous solution is preferably 20 times or less of CMC, more preferably 10 times or less of CMC, and particularly preferably 5 times or less of CMC from the viewpoint of avoiding cloudiness of the aqueous solution.
For the critical micelle concentration (CMC) peculiar to a surfactant, for example, the surface tension of water is measured by changing the concentration of the surfactant with a surface tension meter (manufactured by Kyowa Surfactant), and the surface tension and the surface are measured. The concentration of the turning point in the tension plot (the lowest concentration at which the decrease in surface tension due to the increase in surfactant concentration is contained and the surface tension value becomes constant) is determined as the CMC value. In addition to the above surface tension method, the CMC value can also be obtained by an electric conduction method, a dye method, a fluorescence method, or a viscosity method. In addition, the CMC values of various surfactants described in the literature such as M. J. Rosen, J. T. Kunjappu, Surfactants and interfacial phenomena, 4th edition, John Wiley & Sons (2012) can also be referred to.
水溶液中の界面活性剤の濃度の上限値は、水溶液の白濁を避ける点から、ＣＭＣの２０倍以下が好ましく、ＣＭＣの１０倍以下がより好ましく、ＣＭＣの５倍以下が特に好ましい。
界面活性剤固有の臨界ミセル濃度（ＣＭＣ）は、例えば、表面張力計（協和界面科学社製）によって、界面活性剤の濃度を変化させて水の表面張力を測定し、界面活性剤濃度と表面張力のプロットにおける変曲点の濃度（界面活性剤濃度の増加による表面張力の低下が収まり、表面張力値が一定となる最も低い濃度）がＣＭＣ値として求められる。また、上記の表面張力法以外に、電気伝導法、色素法、蛍光法、粘度法によってもＣＭＣ値を得られる。更に、M. J. Rosen、J. T. Kunjappu編、Surfactants and interfacial phenomena、第４版、John Wiley & Sons社（２０１２年）などの文献に記載されている界面活性剤各種のＣＭＣ値を参照することもできる。 The lower limit of the concentration of the surfactant in the aqueous solution is the critical micelle concentration peculiar to the surfactant because the decrease in surface tension makes it easier for bubbles to separate from the surface of the photocatalyst and the diffusion of the gas generated by water splitting is excellent. 0.25 times or more of (CMC) is preferable, 0.5 times or more of CMC is more preferable, and 1 time or more of CMC is particularly preferable.
The upper limit of the concentration of the surfactant in the aqueous solution is preferably 20 times or less of CMC, more preferably 10 times or less of CMC, and particularly preferably 5 times or less of CMC from the viewpoint of avoiding cloudiness of the aqueous solution.
For the critical micelle concentration (CMC) peculiar to a surfactant, for example, the surface tension of water is measured by changing the concentration of the surfactant with a surface tension meter (manufactured by Kyowa Surfactant), and the surface tension and the surface are measured. The concentration of the turning point in the tension plot (the lowest concentration at which the decrease in surface tension due to the increase in surfactant concentration is contained and the surface tension value becomes constant) is determined as the CMC value. In addition to the above surface tension method, the CMC value can also be obtained by an electric conduction method, a dye method, a fluorescence method, or a viscosity method. In addition, the CMC values of various surfactants described in the literature such as M. J. Rosen, J. T. Kunjappu, Surfactants and interfacial phenomena, 4th edition, John Wiley & Sons (2012) can also be referred to.
＜光触媒付き基材＞
光触媒付き基材２０は、基材２２と、基材２２上に固定化された光触媒２４とを有する。光触媒付き基材２０は、光触媒２４が水溶液１０に接触するように、水溶液１０中に浸漬している。 <Base material with photocatalyst>
The photocatalyst-attachedbase material 20 has a base material 22 and a photocatalyst 24 immobilized on the base material 22. The base material 20 with a photocatalyst is immersed in the aqueous solution 10 so that the photocatalyst 24 comes into contact with the aqueous solution 10.
光触媒付き基材２０は、基材２２と、基材２２上に固定化された光触媒２４とを有する。光触媒付き基材２０は、光触媒２４が水溶液１０に接触するように、水溶液１０中に浸漬している。 <Base material with photocatalyst>
The photocatalyst-attached
（基材）
基材２２は、光触媒２４を支持する部材である。基材２２を構成する材料の具体例としては、金属、有機化合物（例えば、ポリアクリレート、ポリメタクリレート、ポリカーボネート、ポリプロピレン、ポリエチレン、ポリスチレン、ポリエチレンテレフタレート、ポリエチレンナフタレート）、無機化合物（例えば、ＳｒＴｉＯ３等の金属酸化物、ガラス、セラミックス）が挙げられる。
基材２２の形状は特に限定されず、平板状、パンチングメタル状、メッシュ状、格子状、または、貫通した細孔を持つ多孔体であってもよい。
基材２２の厚みは、特に限定されるものではなく、容器１０の大きさに応じて適宜選択することができる。 (Base material)
Thebase material 22 is a member that supports the photocatalyst 24. Specific examples of the material constituting the base material 22 include metals, organic compounds (for example, polyacrylate, polymethacrylate, polycarbonate, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polyethylene naphthalate), inorganic compounds (for example, SrTiO 3 and the like). Metal oxides, glass, ceramics).
The shape of thebase material 22 is not particularly limited, and may be a flat plate shape, a punching metal shape, a mesh shape, a lattice shape, or a porous body having penetrating pores.
The thickness of thebase material 22 is not particularly limited and can be appropriately selected depending on the size of the container 10.
基材２２は、光触媒２４を支持する部材である。基材２２を構成する材料の具体例としては、金属、有機化合物（例えば、ポリアクリレート、ポリメタクリレート、ポリカーボネート、ポリプロピレン、ポリエチレン、ポリスチレン、ポリエチレンテレフタレート、ポリエチレンナフタレート）、無機化合物（例えば、ＳｒＴｉＯ３等の金属酸化物、ガラス、セラミックス）が挙げられる。
基材２２の形状は特に限定されず、平板状、パンチングメタル状、メッシュ状、格子状、または、貫通した細孔を持つ多孔体であってもよい。
基材２２の厚みは、特に限定されるものではなく、容器１０の大きさに応じて適宜選択することができる。 (Base material)
The
The shape of the
The thickness of the
図１の例では、基材２２は単層構造であるが、基材２２は、複層構造であってもよい。 基材２２が複層構造である場合、基材２２としては、支持体層と、支持体層上に配置された導電層と、を有する態様が挙げられる。
支持体層を構成する材料としては、上述の基材２２を構成する材料が挙げられる。
導電層を構成する材料としては、金属（例えば、Ｓｎ、Ｔｉ、Ｔａ、Ａｕ）、ＳｒＲｕＯ３、ＩＴＯ（酸化インジウムスズ）、酸化亜鉛系の透明導電材料（Ａｌ：ＺｎＯ，Ｉｎ：ＺｎＯ，Ｇａ：ＺｎＯ等）が挙げられる。なお、Ａｌ：ＺｎＯ等の「金属原子：金属酸化物」との表記は、金属酸化物を構成する金属（Ａｌ：ＺｎＯの場合には、Ｚｎ）の一部を、金属原子（Ａｌ：ＺｎＯの場合には、Ａｌ）で置換したものを意味する。 In the example of FIG. 1, thebase material 22 has a single-layer structure, but the base material 22 may have a multi-layer structure. When the base material 22 has a multi-layer structure, the base material 22 may include a support layer and a conductive layer arranged on the support layer.
Examples of the material constituting the support layer include the material constituting the above-mentionedbase material 22.
Materials constituting the conductive layer include metals (for example, Sn, Ti, Ta, Au), SrRuO 3 , ITO (indium tin oxide), and zinc oxide-based transparent conductive materials (Al: ZnO, In: ZnO, Ga: ZnO, etc.). In addition, in the notation of "metal atom: metal oxide" such as Al: ZnO, a part of the metal (Zn in the case of Al: ZnO) constituting the metal oxide is referred to as a metal atom (Al: ZnO). In the case, it means the one replaced with Al).
支持体層を構成する材料としては、上述の基材２２を構成する材料が挙げられる。
導電層を構成する材料としては、金属（例えば、Ｓｎ、Ｔｉ、Ｔａ、Ａｕ）、ＳｒＲｕＯ３、ＩＴＯ（酸化インジウムスズ）、酸化亜鉛系の透明導電材料（Ａｌ：ＺｎＯ，Ｉｎ：ＺｎＯ，Ｇａ：ＺｎＯ等）が挙げられる。なお、Ａｌ：ＺｎＯ等の「金属原子：金属酸化物」との表記は、金属酸化物を構成する金属（Ａｌ：ＺｎＯの場合には、Ｚｎ）の一部を、金属原子（Ａｌ：ＺｎＯの場合には、Ａｌ）で置換したものを意味する。 In the example of FIG. 1, the
Examples of the material constituting the support layer include the material constituting the above-mentioned
Materials constituting the conductive layer include metals (for example, Sn, Ti, Ta, Au), SrRuO 3 , ITO (indium tin oxide), and zinc oxide-based transparent conductive materials (Al: ZnO, In: ZnO, Ga: ZnO, etc.). In addition, in the notation of "metal atom: metal oxide" such as Al: ZnO, a part of the metal (Zn in the case of Al: ZnO) constituting the metal oxide is referred to as a metal atom (Al: ZnO). In the case, it means the one replaced with Al).
（光触媒）
光触媒２４は、基材２２上に固定されている。水溶液Ｓ中の光触媒２４に光Ｌが照射されることで、光触媒２４の表面で気体（具体的には、酸素および水素の少なくとも一方）が発生する。
図１の例では、光触媒２４は、基材２２の一部分に配置されているが、基材２２の全体に配置されていてもよい。
光触媒２４は、基材２２上で複数の光触媒粒子が連続して存在するような形態（すなわち、光触媒層を構成する形態）で存在してもよいし、基材２２上で複数の光触媒粒子が非連続に存在する形態で存在してもよい。
光触媒２４が層状に形成された光触媒層である場合、光触媒層の厚みは、０．１～１０００μｍが好ましく、１～１００μｍが特に好ましい。 (photocatalyst)
Thephotocatalyst 24 is fixed on the base material 22. When the photocatalyst 24 in the aqueous solution S is irradiated with light L, a gas (specifically, at least one of oxygen and hydrogen) is generated on the surface of the photocatalyst 24.
In the example of FIG. 1, thephotocatalyst 24 is arranged on a part of the base material 22, but may be arranged on the whole of the base material 22.
Thephotocatalyst 24 may exist in a form in which a plurality of photocatalyst particles are continuously present on the base material 22 (that is, a form constituting the photocatalyst layer), or a plurality of photocatalyst particles are present on the base material 22. It may exist in a form that exists discontinuously.
When thephotocatalyst 24 is a layered photocatalyst layer, the thickness of the photocatalyst layer is preferably 0.1 to 1000 μm, and particularly preferably 1 to 100 μm.
光触媒２４は、基材２２上に固定されている。水溶液Ｓ中の光触媒２４に光Ｌが照射されることで、光触媒２４の表面で気体（具体的には、酸素および水素の少なくとも一方）が発生する。
図１の例では、光触媒２４は、基材２２の一部分に配置されているが、基材２２の全体に配置されていてもよい。
光触媒２４は、基材２２上で複数の光触媒粒子が連続して存在するような形態（すなわち、光触媒層を構成する形態）で存在してもよいし、基材２２上で複数の光触媒粒子が非連続に存在する形態で存在してもよい。
光触媒２４が層状に形成された光触媒層である場合、光触媒層の厚みは、０．１～１０００μｍが好ましく、１～１００μｍが特に好ましい。 (photocatalyst)
The
In the example of FIG. 1, the
The
When the
光触媒２４を基材２２上で固定化する方法としては、特に限定されず、例えば、光触媒粒子を溶媒に分散させて懸濁液（スラリー）として、基材上に懸濁液を塗布して、必要に応じて乾燥する方法が挙げられる。
懸濁液の溶媒としては、水、メタノール、エタノール等のアルコール類、アセトン等のケトン類、ベンゼン、トルエン、キシレン等が挙げられる。なお、溶媒に光触媒粒子を分散させる場合、超音波処理を施すことで、光触媒粒子を溶媒中に均一に分散させることができる。なお、懸濁液中に界面活性剤を含ませることで光触媒粒子を均一に分散させることもできるが、光触媒層中に残留する界面活性剤が光触媒の反応効率を低下させるため、界面活性剤を含まない懸濁液が好ましい。
基材上に上記懸濁液を塗布する方法は特に限定されず、例えば、ドロップキャスト法、スプレー法、ディップ法、スキージ法、ドクターブレード法、スピンコート法、スクリーンコート法、ロールコーティング法、インクジェット法、粒子転写法などの公知の方法が挙げられる。塗布後の乾燥条件としては、溶媒の沸点以上の温度に保持すればよい。 The method for immobilizing thephotocatalyst 24 on the substrate 22 is not particularly limited, and for example, the photocatalyst particles are dispersed in a solvent to form a suspension (slurry), and the suspension is applied onto the substrate. Examples include a method of drying as needed.
Examples of the solvent of the suspension include water, alcohols such as methanol and ethanol, ketones such as acetone, benzene, toluene and xylene. When the photocatalyst particles are dispersed in the solvent, the photocatalyst particles can be uniformly dispersed in the solvent by performing ultrasonic treatment. Although it is possible to uniformly disperse the photocatalyst particles by including the surfactant in the suspension, the surfactant remaining in the photocatalyst layer reduces the reaction efficiency of the photocatalyst. Suspensions that do not contain are preferred.
The method of applying the suspension on the substrate is not particularly limited, and for example, a drop casting method, a spray method, a dip method, a squeegee method, a doctor blade method, a spin coating method, a screen coating method, a roll coating method, and an inkjet method. Known methods such as a method and a particle transfer method can be mentioned. As the drying condition after coating, the temperature may be maintained at a temperature equal to or higher than the boiling point of the solvent.
懸濁液の溶媒としては、水、メタノール、エタノール等のアルコール類、アセトン等のケトン類、ベンゼン、トルエン、キシレン等が挙げられる。なお、溶媒に光触媒粒子を分散させる場合、超音波処理を施すことで、光触媒粒子を溶媒中に均一に分散させることができる。なお、懸濁液中に界面活性剤を含ませることで光触媒粒子を均一に分散させることもできるが、光触媒層中に残留する界面活性剤が光触媒の反応効率を低下させるため、界面活性剤を含まない懸濁液が好ましい。
基材上に上記懸濁液を塗布する方法は特に限定されず、例えば、ドロップキャスト法、スプレー法、ディップ法、スキージ法、ドクターブレード法、スピンコート法、スクリーンコート法、ロールコーティング法、インクジェット法、粒子転写法などの公知の方法が挙げられる。塗布後の乾燥条件としては、溶媒の沸点以上の温度に保持すればよい。 The method for immobilizing the
Examples of the solvent of the suspension include water, alcohols such as methanol and ethanol, ketones such as acetone, benzene, toluene and xylene. When the photocatalyst particles are dispersed in the solvent, the photocatalyst particles can be uniformly dispersed in the solvent by performing ultrasonic treatment. Although it is possible to uniformly disperse the photocatalyst particles by including the surfactant in the suspension, the surfactant remaining in the photocatalyst layer reduces the reaction efficiency of the photocatalyst. Suspensions that do not contain are preferred.
The method of applying the suspension on the substrate is not particularly limited, and for example, a drop casting method, a spray method, a dip method, a squeegee method, a doctor blade method, a spin coating method, a screen coating method, a roll coating method, and an inkjet method. Known methods such as a method and a particle transfer method can be mentioned. As the drying condition after coating, the temperature may be maintained at a temperature equal to or higher than the boiling point of the solvent.
光触媒２４を構成する材料としては、酸化物、酸窒化物、窒化物およびカルコゲナイド化合物からなる群から選択される少なくとも一種の光触媒化合物が挙げられる。光触媒化合物は、Ｓｒ、Ｎａ、Ｍｇ、Ａｌ、Ｓｉ、Ｃａ、Ｔｉ、Ｖ、Ｆｅ、Ｃｕ、Ｚｎ、Ｇａ、Ｙ、Ｚｒ、Ｎｂ、Ａｇ、Ｉｎ、Ｓｎ、Ｂａ、Ｌａ、Ｔａ、ＷおよびＢｉからなる群より選択される少なくとも１種の元素を含むことが好ましい。
Examples of the material constituting the photocatalyst 24 include at least one photocatalyst compound selected from the group consisting of oxides, oxynitrides, nitrides and chalcogenide compounds. Photocatalytic compounds are from Sr, Na, Mg, Al, Si, Ca, Ti, V, Fe, Cu, Zn, Ga, Y, Zr, Nb, Ag, In, Sn, Ba, La, Ta, W and Bi. It is preferable to contain at least one element selected from the group.
光触媒２４の好適態様の一つとしては、水素発生用光触媒化合物および酸素発生用光触媒化合物の両方の光触媒化合物を含む態様が挙げられる。
水素発生用光触媒化合物の具体例としては、ＢａＮｂＯ２Ｎ、ＢａＴａＯ２Ｎ、ＬａＴｉＯ２Ｎ、ＴａＯＮ等の酸窒化物、Ｔａ３Ｎ５等の窒化物、ならびに、Ｙ２Ｔｉ２Ｏ５Ｓ２、Ｌａ５Ｔｉ２Ｃｕ０．９Ａｇ０．１Ｓ５Ｏ７、Ｃｕ３ＶＳ４、（ＣｕＧａ）０．５ＺｎＳ２、Ｃｕ０．８Ｇａ０．４Ｉｎ０．４Ｚｎ０．４Ｓ２、ＣｕＩｎＧａＳｅ、Ｃｕ（ＧａＩｎ）０．５Ｓ２、Ｃｕ０．８Ａｇ０．２ＧａＳ２、（ＣｕＡｇ）０．１Ｉｎ０．２Ｚｎ１．６Ｓ２、ＣｕＩｎＳ２、ＧａＡｓ、ＧａＩｎＰ、ＡｌＧａＩｎＰ、ＣｄＴｅおよび、ＺｎＳｅとＣｕｘＧａ２－ｘＳｅとの固溶体、ＣＩＧＳ化合物半導体（Ｃｕ、Ｉｎ、ＧａおよびＳｅを主原料とする化合物半導体）、Ｃｕ２ＺｎＳｎＳ４等のＣＺＴＳ化合物半導体等のカルコゲナイド化合物、Ｃｒ、Ｒｈ、ＴａおよびＩｒからなる群から選択される少なくとも１種の元素をドープしたＳｒＴｉＯ３が挙げられ、ここに例示した材料に限定されるものではないが、気体発生量ならびに耐久性に優れる点から、Ｃｒ、Ｒｈ、ＴａおよびＩｒからなる群から選択される少なくとも１種の元素をドープしたＳｒＴｉＯ３、ＣＩＧＳ化合物半導体、Ｔａ３Ｎ５等の窒化物、ならびに、ＢａＴａＯ２Ｎ、ＬａＴｉＯ２ＮおよびＴａＯＮ等の酸窒化物が好ましい。
酸素発生用光触媒化合物の具体例としては、水素発生用光触媒化合物で例示したもの以外に、ＴｉＯ２、Ｆｅ２Ｏ３、ＷＯ３、ＢｉＶＯ４、および、Ｂｉ２ＷＯ６等の酸化物が挙げられ、ここに例示した材料に限定されるものではないが、気体発生量ならびに耐久性に優れる点から、ＴｉＯ２、Ｆｅ２Ｏ３、ＷＯ３、ＢｉＶＯ４、および、Ｂｉ２ＷＯ６、Ｔａ３Ｎ５等の窒化物、ならびに、ＢａＴａＯ２Ｎ、ＬａＴｉＯ２ＮおよびＴａＯＮ等の酸窒化物が好ましい。 One of the preferred embodiments of thephotocatalyst 24 includes an embodiment containing both a photocatalyst compound for hydrogen generation and a photocatalyst compound for oxygen generation.
Specific examples of the photocatalyst compound for hydrogen generation include oxynitrides such as BaNbO 2 N, BaTaO 2 N, LaTIO 2 N, and TaON, nitrides such as Ta 3 N 5 , and Y 2 Ti 2 O 5 S 2 , and so on. La 5 Ti 2 Cu 0.9 Ag 0.1 S 5 O 7 , Cu 3 VS 4 , (CuGa) 0.5 ZnS 2 , Cu 0.8 Ga 0.4 In 0.4 Zn 0.4 S 2 , CuInGaSe, Cu (GaIn) 0.5 S 2 , Cu 0.8 Ag 0.2 GaS 2 , (CuAg) 0.1 In 0.2 Zn 1.6 S 2 , CuInS 2 , GaAs, GaInP, AlGaInP, CdTe And, solid solution of ZnSe and Cu x Ga 2-x Se, CIGS compound semiconductor (compound semiconductor whose main raw materials are Cu, In, Ga and Se), chalcogenide compound such as CZTS compound semiconductor such as Cu 2 ZnSnS 4 , Cr. SrTIO 3 doped with at least one element selected from the group consisting of, Rh, Ta and Ir, and is not limited to the materials exemplified here, but is excellent in gas generation amount and durability. From SrTIO 3 , CIGS compound semiconductors, nitrides such as Ta 3 N 5 , and BaTaO 2 N, LaTIO 2 N and Acid nitrides such as TaON are preferred.
Specific examples of the photocatalytic compound for oxygen generation include oxides such as TIO 2 , Fe 2 O 3 , WO 3 , BiVO 4 , and Bi 2 WO 6 in addition to those exemplified for the photocatalytic compound for hydrogen generation. , But not limited to the materials exemplified here, from the viewpoint of excellent gas generation amount and durability, TiO 2 , Fe 2 O 3 , WO 3 , BiVO 4 , and Bi 2 WO 6 , Ta 3 N. Nitrides such as 5 and oxynitrides such as BaTaO 2 N, LaTIO 2 N and TaON are preferred.
水素発生用光触媒化合物の具体例としては、ＢａＮｂＯ２Ｎ、ＢａＴａＯ２Ｎ、ＬａＴｉＯ２Ｎ、ＴａＯＮ等の酸窒化物、Ｔａ３Ｎ５等の窒化物、ならびに、Ｙ２Ｔｉ２Ｏ５Ｓ２、Ｌａ５Ｔｉ２Ｃｕ０．９Ａｇ０．１Ｓ５Ｏ７、Ｃｕ３ＶＳ４、（ＣｕＧａ）０．５ＺｎＳ２、Ｃｕ０．８Ｇａ０．４Ｉｎ０．４Ｚｎ０．４Ｓ２、ＣｕＩｎＧａＳｅ、Ｃｕ（ＧａＩｎ）０．５Ｓ２、Ｃｕ０．８Ａｇ０．２ＧａＳ２、（ＣｕＡｇ）０．１Ｉｎ０．２Ｚｎ１．６Ｓ２、ＣｕＩｎＳ２、ＧａＡｓ、ＧａＩｎＰ、ＡｌＧａＩｎＰ、ＣｄＴｅおよび、ＺｎＳｅとＣｕｘＧａ２－ｘＳｅとの固溶体、ＣＩＧＳ化合物半導体（Ｃｕ、Ｉｎ、ＧａおよびＳｅを主原料とする化合物半導体）、Ｃｕ２ＺｎＳｎＳ４等のＣＺＴＳ化合物半導体等のカルコゲナイド化合物、Ｃｒ、Ｒｈ、ＴａおよびＩｒからなる群から選択される少なくとも１種の元素をドープしたＳｒＴｉＯ３が挙げられ、ここに例示した材料に限定されるものではないが、気体発生量ならびに耐久性に優れる点から、Ｃｒ、Ｒｈ、ＴａおよびＩｒからなる群から選択される少なくとも１種の元素をドープしたＳｒＴｉＯ３、ＣＩＧＳ化合物半導体、Ｔａ３Ｎ５等の窒化物、ならびに、ＢａＴａＯ２Ｎ、ＬａＴｉＯ２ＮおよびＴａＯＮ等の酸窒化物が好ましい。
酸素発生用光触媒化合物の具体例としては、水素発生用光触媒化合物で例示したもの以外に、ＴｉＯ２、Ｆｅ２Ｏ３、ＷＯ３、ＢｉＶＯ４、および、Ｂｉ２ＷＯ６等の酸化物が挙げられ、ここに例示した材料に限定されるものではないが、気体発生量ならびに耐久性に優れる点から、ＴｉＯ２、Ｆｅ２Ｏ３、ＷＯ３、ＢｉＶＯ４、および、Ｂｉ２ＷＯ６、Ｔａ３Ｎ５等の窒化物、ならびに、ＢａＴａＯ２Ｎ、ＬａＴｉＯ２ＮおよびＴａＯＮ等の酸窒化物が好ましい。 One of the preferred embodiments of the
Specific examples of the photocatalyst compound for hydrogen generation include oxynitrides such as BaNbO 2 N, BaTaO 2 N, LaTIO 2 N, and TaON, nitrides such as Ta 3 N 5 , and Y 2 Ti 2 O 5 S 2 , and so on. La 5 Ti 2 Cu 0.9 Ag 0.1 S 5 O 7 , Cu 3 VS 4 , (CuGa) 0.5 ZnS 2 , Cu 0.8 Ga 0.4 In 0.4 Zn 0.4 S 2 , CuInGaSe, Cu (GaIn) 0.5 S 2 , Cu 0.8 Ag 0.2 GaS 2 , (CuAg) 0.1 In 0.2 Zn 1.6 S 2 , CuInS 2 , GaAs, GaInP, AlGaInP, CdTe And, solid solution of ZnSe and Cu x Ga 2-x Se, CIGS compound semiconductor (compound semiconductor whose main raw materials are Cu, In, Ga and Se), chalcogenide compound such as CZTS compound semiconductor such as Cu 2 ZnSnS 4 , Cr. SrTIO 3 doped with at least one element selected from the group consisting of, Rh, Ta and Ir, and is not limited to the materials exemplified here, but is excellent in gas generation amount and durability. From SrTIO 3 , CIGS compound semiconductors, nitrides such as Ta 3 N 5 , and BaTaO 2 N, LaTIO 2 N and Acid nitrides such as TaON are preferred.
Specific examples of the photocatalytic compound for oxygen generation include oxides such as TIO 2 , Fe 2 O 3 , WO 3 , BiVO 4 , and Bi 2 WO 6 in addition to those exemplified for the photocatalytic compound for hydrogen generation. , But not limited to the materials exemplified here, from the viewpoint of excellent gas generation amount and durability, TiO 2 , Fe 2 O 3 , WO 3 , BiVO 4 , and Bi 2 WO 6 , Ta 3 N. Nitrides such as 5 and oxynitrides such as BaTaO 2 N, LaTIO 2 N and TaON are preferred.
光触媒２４の好適態様の一つとしては、ＧａＮとＺｎＯの固溶体、ＬａＴｉＯ２ＮおよびＴａＯＮ等の酸窒化物、Ｔａ３Ｎ５等の窒化物、Ｎａ２Ｔｉ６Ｏ１３、ＳｎＮｂ２Ｏ６、ＢａＴｉ４Ｏ９、Ｎａ、Ａｌ、Ｃｒ、Ｎｉ、Ｒｈ、ＳｂおよびＴａからなる群から選択される少なくとも１種の元素（以下、「特定元素」ともいう。）をドープしたＫＴａＯ３、特定元素をドープしたＳｒＴｉＯ３、ならびに、特定元素をドープしたＴｉＯ２からなる群から選択される少なくとも１種の光触媒化合物を含む態様が挙げられる。これらの光触媒化合物は、光照射による水分解によって、酸素および水素の両方の気体を発生させることができる。
中でも、気体発生量ならびに耐久性に優れる点から、特定元素をドープしたＳｒＴｉＯ３が好ましい。 One of the preferred embodiments of thephotocatalyst 24 is a solid solution of GaN and ZnO, an oxynitride such as LaTIO 2 N and TaON, a nitride such as Ta 3 N 5 , Na 2 Ti 6 O 13 , SnNb 2 O 6 , BaTi. KTaO 3 doped with at least one element selected from the group consisting of 4 O 9 , Na, Al, Cr, Ni, Rh, Sb and Ta (hereinafter, also referred to as “specific element”), doped with a specific element. Examples thereof include SrTiO 3 and at least one photocatalytic compound selected from the group consisting of TiO 2 doped with a specific element. These photocatalytic compounds can generate both oxygen and hydrogen gases by water splitting with light irradiation.
Of these, SrTiO 3 doped with a specific element is preferable from the viewpoint of excellent gas generation amount and durability.
中でも、気体発生量ならびに耐久性に優れる点から、特定元素をドープしたＳｒＴｉＯ３が好ましい。 One of the preferred embodiments of the
Of these, SrTiO 3 doped with a specific element is preferable from the viewpoint of excellent gas generation amount and durability.
光触媒２４は、その表面に助触媒が担持されていてもよい。助触媒が担持されていれば、気体生成効率がより良好になる。
助触媒を担持させる方法としては、特に限定されず、例えば、塗布焼成法、光電着法、真空蒸着法、スパッタ法または含浸法等により形成できる。
助触媒を構成する材料としては、例えば、Ｐｔ、Ｐｄ、Ｎｉ、Ａｕ、Ａｇ、Ｒｕ、Ｃｕ、Ｃｏ、Ｃｒ、Ｒｈ、ＩｒまたはＭｎ等により構成される単体、およびそれらを組み合わせた合金、ならびにその酸化物が挙げられる。
助触媒のサイズは、特に限定されるものではなく、０．５ｎｍ～１μｍであり、高さが数ｎｍ程度であるのが好ましい。 Thephotocatalyst 24 may have a co-catalyst supported on its surface. If a co-catalyst is supported, the gas generation efficiency becomes better.
The method for supporting the co-catalyst is not particularly limited, and can be formed by, for example, a coating firing method, a photoelectric deposition method, a vacuum vapor deposition method, a sputtering method, an impregnation method, or the like.
Examples of the material constituting the co-catalyst include simple substances composed of Pt, Pd, Ni, Au, Ag, Ru, Cu, Co, Cr, Rh, Ir, Mn and the like, alloys obtained by combining them, and the like. Oxides can be mentioned.
The size of the co-catalyst is not particularly limited, and is preferably 0.5 nm to 1 μm and a height of about several nm.
助触媒を担持させる方法としては、特に限定されず、例えば、塗布焼成法、光電着法、真空蒸着法、スパッタ法または含浸法等により形成できる。
助触媒を構成する材料としては、例えば、Ｐｔ、Ｐｄ、Ｎｉ、Ａｕ、Ａｇ、Ｒｕ、Ｃｕ、Ｃｏ、Ｃｒ、Ｒｈ、ＩｒまたはＭｎ等により構成される単体、およびそれらを組み合わせた合金、ならびにその酸化物が挙げられる。
助触媒のサイズは、特に限定されるものではなく、０．５ｎｍ～１μｍであり、高さが数ｎｍ程度であるのが好ましい。 The
The method for supporting the co-catalyst is not particularly limited, and can be formed by, for example, a coating firing method, a photoelectric deposition method, a vacuum vapor deposition method, a sputtering method, an impregnation method, or the like.
Examples of the material constituting the co-catalyst include simple substances composed of Pt, Pd, Ni, Au, Ag, Ru, Cu, Co, Cr, Rh, Ir, Mn and the like, alloys obtained by combining them, and the like. Oxides can be mentioned.
The size of the co-catalyst is not particularly limited, and is preferably 0.5 nm to 1 μm and a height of about several nm.
＜その他の構成＞
光触媒２４の表面付近で発生した気体は、例えば、容器１０に接続された図示しない配管から回収できる。また、容器１０には、水溶液Ｓを供給するための図示しない供給管およびポンプ等が接続されていてもよい。
また、水分解装置１は、光Ｌとして太陽光を利用しない場合には、図示しない光源（キセノンランプ等）を有していてもよい。 <Other configurations>
The gas generated near the surface of thephotocatalyst 24 can be recovered, for example, from a pipe (not shown) connected to the container 10. Further, a supply pipe (not shown), a pump, or the like for supplying the aqueous solution S may be connected to the container 10.
Further, the water splitting device 1 may have a light source (xenon lamp or the like) (not shown) when sunlight is not used as the light L.
光触媒２４の表面付近で発生した気体は、例えば、容器１０に接続された図示しない配管から回収できる。また、容器１０には、水溶液Ｓを供給するための図示しない供給管およびポンプ等が接続されていてもよい。
また、水分解装置１は、光Ｌとして太陽光を利用しない場合には、図示しない光源（キセノンランプ等）を有していてもよい。 <Other configurations>
The gas generated near the surface of the
Further, the water splitting device 1 may have a light source (xenon lamp or the like) (not shown) when sunlight is not used as the light L.
＜他の態様＞
図１の例では、水分解装置が光触媒付き基材を有する態様を示したが、本発明の水分解装置は、光触媒付き基材の代わりに、上記容器の内壁面上に固定された光触媒を有する態様であってもよい。この場合、光触媒は、水溶液に浸漬する位置に配置されるのであれば、容器の内壁面上のいずれの位置に固定化されてもよい。
光触媒を容器の内壁面上で固定化する方法としては、特に限定されないが、例えば、光触媒を基材に固定化する方法と同様の方法が挙げられる。 <Other aspects>
In the example of FIG. 1, the embodiment in which the water splitting device has a base material with a photocatalyst is shown, but the water splitting device of the present invention uses a photocatalyst fixed on the inner wall surface of the container instead of the base material with a photocatalyst. It may be a mode to have. In this case, the photocatalyst may be immobilized at any position on the inner wall surface of the container as long as it is arranged at a position where it is immersed in the aqueous solution.
The method of immobilizing the photocatalyst on the inner wall surface of the container is not particularly limited, and examples thereof include the same method as the method of immobilizing the photocatalyst on the substrate.
図１の例では、水分解装置が光触媒付き基材を有する態様を示したが、本発明の水分解装置は、光触媒付き基材の代わりに、上記容器の内壁面上に固定された光触媒を有する態様であってもよい。この場合、光触媒は、水溶液に浸漬する位置に配置されるのであれば、容器の内壁面上のいずれの位置に固定化されてもよい。
光触媒を容器の内壁面上で固定化する方法としては、特に限定されないが、例えば、光触媒を基材に固定化する方法と同様の方法が挙げられる。 <Other aspects>
In the example of FIG. 1, the embodiment in which the water splitting device has a base material with a photocatalyst is shown, but the water splitting device of the present invention uses a photocatalyst fixed on the inner wall surface of the container instead of the base material with a photocatalyst. It may be a mode to have. In this case, the photocatalyst may be immobilized at any position on the inner wall surface of the container as long as it is arranged at a position where it is immersed in the aqueous solution.
The method of immobilizing the photocatalyst on the inner wall surface of the container is not particularly limited, and examples thereof include the same method as the method of immobilizing the photocatalyst on the substrate.
［気体の製造方法］
本発明の気体の製造方法は、上述の本発明の水分解装置を用いた気体の製造方法であって、上記水分解装置が有する光触媒に光を照射することによって、上記光触媒の表面から気体を発生させる。発生する気体としては、水素および酸素が挙げられる。
本発明の気体の製造方法では、上述の本発明の水分解装置を用いるため、初期の気体発生量に優れる。 [Gas manufacturing method]
The method for producing a gas of the present invention is a method for producing a gas using the above-mentioned water decomposition apparatus of the present invention, and by irradiating the photocatalyst of the above-mentioned water decomposition apparatus with light, gas is removed from the surface of the above-mentioned photocatalyst. generate. Examples of the generated gas include hydrogen and oxygen.
In the method for producing gas of the present invention, since the above-mentioned water decomposition apparatus of the present invention is used, the initial amount of gas generated is excellent.
本発明の気体の製造方法は、上述の本発明の水分解装置を用いた気体の製造方法であって、上記水分解装置が有する光触媒に光を照射することによって、上記光触媒の表面から気体を発生させる。発生する気体としては、水素および酸素が挙げられる。
本発明の気体の製造方法では、上述の本発明の水分解装置を用いるため、初期の気体発生量に優れる。 [Gas manufacturing method]
The method for producing a gas of the present invention is a method for producing a gas using the above-mentioned water decomposition apparatus of the present invention, and by irradiating the photocatalyst of the above-mentioned water decomposition apparatus with light, gas is removed from the surface of the above-mentioned photocatalyst. generate. Examples of the generated gas include hydrogen and oxygen.
In the method for producing gas of the present invention, since the above-mentioned water decomposition apparatus of the present invention is used, the initial amount of gas generated is excellent.
以下に実施例に基づいて本発明をさらに詳細に説明する。以下の実施例に示す材料、使用量、割合、処理内容および処理手順等は、本発明の趣旨を逸脱しない限り適宜変更することができる。したがって、本発明の範囲は以下に示す実施例により限定的に解釈されるべきものではない。
The present invention will be described in more detail below based on examples. The materials, amounts, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limiting by the examples shown below.
［実施例１］
（光触媒付き基材の製造）
「Ｊｏｕｌｅ，Ｖｏｌ．２，ｐｐ．５０９－５２０、２０１７年」記載の方法により、水素発生助触媒であるＲｈＣｒＯｘを担持した光触媒であるＳｒＴｉＯ３：Ａｌの粉体と、親水性シリカ粒子とを、超音波処理によって純水に分散させて、界面活性剤を含まない懸濁液を得た。この懸濁液をガラス板上に、ドロップキャストした後に乾燥して固定化させて、３ｃｍ角の正方形となるように切断して、光触媒付き基材を得た。なお、ＳｒＴｉＯ３：Ａｌとは、ＡｌをドープしたＳｒＴｉＯ３を意味する。 [Example 1]
(Manufacturing of base material with photocatalyst)
By the method described in "Joule, Vol. 2, pp. 509-520, 2017", powder of SrTiO 3 : Al, which is a photocatalyst carrying RhCrO x , which is a hydrogen generation assisting catalyst, and hydrophilic silica particles are prepared. , Dispersed in pure water by ultrasonic treatment to obtain a suspension containing no surfactant. This suspension was drop-cast on a glass plate, dried and immobilized, and cut into a 3 cm square square to obtain a photocatalytic substrate. In addition, SrTiO 3 : Al means SrTiO 3 doped with Al.
（光触媒付き基材の製造）
「Ｊｏｕｌｅ，Ｖｏｌ．２，ｐｐ．５０９－５２０、２０１７年」記載の方法により、水素発生助触媒であるＲｈＣｒＯｘを担持した光触媒であるＳｒＴｉＯ３：Ａｌの粉体と、親水性シリカ粒子とを、超音波処理によって純水に分散させて、界面活性剤を含まない懸濁液を得た。この懸濁液をガラス板上に、ドロップキャストした後に乾燥して固定化させて、３ｃｍ角の正方形となるように切断して、光触媒付き基材を得た。なお、ＳｒＴｉＯ３：Ａｌとは、ＡｌをドープしたＳｒＴｉＯ３を意味する。 [Example 1]
(Manufacturing of base material with photocatalyst)
By the method described in "Joule, Vol. 2, pp. 509-520, 2017", powder of SrTiO 3 : Al, which is a photocatalyst carrying RhCrO x , which is a hydrogen generation assisting catalyst, and hydrophilic silica particles are prepared. , Dispersed in pure water by ultrasonic treatment to obtain a suspension containing no surfactant. This suspension was drop-cast on a glass plate, dried and immobilized, and cut into a 3 cm square square to obtain a photocatalytic substrate. In addition, SrTiO 3 : Al means SrTiO 3 doped with Al.
（水溶液の調製）
臭化ドデシルトリメチルアンモニウム（カチオン性界面活性剤。下記式Ｉ－１参照。）の濃度が表１の値になるように、臭化ドデシルトリメチルアンモニウムと純水とを混合および攪拌して、水溶液Ｓ１を得た。 (Preparation of aqueous solution)
Aqueous solution S1 is prepared by mixing and stirring dodecyltrimethylammonium bromide and pure water so that the concentration of dodecyltrimethylammonium bromide (cationic surfactant; see formula I-1 below) is as shown in Table 1. Got
臭化ドデシルトリメチルアンモニウム（カチオン性界面活性剤。下記式Ｉ－１参照。）の濃度が表１の値になるように、臭化ドデシルトリメチルアンモニウムと純水とを混合および攪拌して、水溶液Ｓ１を得た。 (Preparation of aqueous solution)
Aqueous solution S1 is prepared by mixing and stirring dodecyltrimethylammonium bromide and pure water so that the concentration of dodecyltrimethylammonium bromide (cationic surfactant; see formula I-1 below) is as shown in Table 1. Got
（評価１：水溶液の酸化ピーク電位の測定）
水溶液Ｓ１の酸化ピーク電位の測定は、電気化学測定システム（北斗電工、ＨＺ－７０００）を用いた電気化学測定により行った。
具体的には、硼珪酸ガラス製の反応容器（直径６ｃｍ、高さ７ｃｍ）を用い、作用極および対極に白金（Ｐｔ）線、参照電極にＡｇ／ＡｇＣｌ電極（東陽テクニカ、ＴＲＥ－１０Ｄ－２００－ＩＮＡＧＳＥ－２０）を用いた。
水溶液Ｓ１に、支持電解質として、りん酸二水素ナトリウム（ＮａＨ２ＰＯ４、０．０５ｍоｌ／Ｌ）とりん酸水素二ナトリウム（Ｎａ２ＨＰＯ４、０．０５ｍоｌ／Ｌ）とを加えた。
上記支持電解質を加えた水溶液Ｓ１を上記反応容器内に０．１Ｌ注ぎ、反応容器内にアルゴンを１０分間流した後、サイクリックボルタンメトリー法による電気化学測定を行って、水溶液Ｓ１の酸化ピーク電位を求めた。なお、掃引範囲は、－０．１Ｖ ｖｓ．ＲＨＥ～１．８Ｖ ｖｓ．ＲＨＥ、掃引速度は、０．０５Ｖ／ｓ、測定温度は、２５℃とした。
得られた酸化ピーク電位の値に基づいて、以下の基準により評価した。結果を表１に示す。
Ａ：酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ以上
Ｂ：酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ未満 (Evaluation 1: Measurement of oxidation peak potential of aqueous solution)
The oxidation peak potential of the aqueous solution S1 was measured by electrochemical measurement using an electrochemical measurement system (Hokuto Denko, HZ-7000).
Specifically, a reaction vessel made of borosilicate glass (diameter 6 cm, height 7 cm) is used, a platinum (Pt) wire is used as the working electrode and the counter electrode, and an Ag / AgCl electrode (Toyo Technica, TRE-10D-200) is used as the reference electrode. -INAGSE-20) was used.
Sodium dihydrogen phosphate (NaH 2 PO 4 , 0.05 mL / L) and disodium hydrogen phosphate (Na 2 HPO 4 , 0.05 mol / L) were added to the aqueous solution S1 as supporting electrolytes.
0.1 L of the aqueous solution S1 to which the supporting electrolyte is added is poured into the reaction vessel, argon is allowed to flow in the reaction vessel for 10 minutes, and then electrochemical measurement is performed by a cyclic voltammetry method to determine the oxidation peak potential of the aqueous solution S1. I asked. The sweep range is -0.1 V vs. RHE ~ 1.8V vs. RHE, the sweep speed was 0.05 V / s, and the measurement temperature was 25 ° C.
Based on the obtained value of the oxidation peak potential, the evaluation was made according to the following criteria. The results are shown in Table 1.
A: Oxidation peak potential is 1.0 V vs. RHE or higher B: Oxidation peak potential is 1.0 V vs. Less than RHE
水溶液Ｓ１の酸化ピーク電位の測定は、電気化学測定システム（北斗電工、ＨＺ－７０００）を用いた電気化学測定により行った。
具体的には、硼珪酸ガラス製の反応容器（直径６ｃｍ、高さ７ｃｍ）を用い、作用極および対極に白金（Ｐｔ）線、参照電極にＡｇ／ＡｇＣｌ電極（東陽テクニカ、ＴＲＥ－１０Ｄ－２００－ＩＮＡＧＳＥ－２０）を用いた。
水溶液Ｓ１に、支持電解質として、りん酸二水素ナトリウム（ＮａＨ２ＰＯ４、０．０５ｍоｌ／Ｌ）とりん酸水素二ナトリウム（Ｎａ２ＨＰＯ４、０．０５ｍоｌ／Ｌ）とを加えた。
上記支持電解質を加えた水溶液Ｓ１を上記反応容器内に０．１Ｌ注ぎ、反応容器内にアルゴンを１０分間流した後、サイクリックボルタンメトリー法による電気化学測定を行って、水溶液Ｓ１の酸化ピーク電位を求めた。なお、掃引範囲は、－０．１Ｖ ｖｓ．ＲＨＥ～１．８Ｖ ｖｓ．ＲＨＥ、掃引速度は、０．０５Ｖ／ｓ、測定温度は、２５℃とした。
得られた酸化ピーク電位の値に基づいて、以下の基準により評価した。結果を表１に示す。
Ａ：酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ以上
Ｂ：酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ未満 (Evaluation 1: Measurement of oxidation peak potential of aqueous solution)
The oxidation peak potential of the aqueous solution S1 was measured by electrochemical measurement using an electrochemical measurement system (Hokuto Denko, HZ-7000).
Specifically, a reaction vessel made of borosilicate glass (diameter 6 cm, height 7 cm) is used, a platinum (Pt) wire is used as the working electrode and the counter electrode, and an Ag / AgCl electrode (Toyo Technica, TRE-10D-200) is used as the reference electrode. -INAGSE-20) was used.
Sodium dihydrogen phosphate (NaH 2 PO 4 , 0.05 mL / L) and disodium hydrogen phosphate (Na 2 HPO 4 , 0.05 mol / L) were added to the aqueous solution S1 as supporting electrolytes.
0.1 L of the aqueous solution S1 to which the supporting electrolyte is added is poured into the reaction vessel, argon is allowed to flow in the reaction vessel for 10 minutes, and then electrochemical measurement is performed by a cyclic voltammetry method to determine the oxidation peak potential of the aqueous solution S1. I asked. The sweep range is -0.1 V vs. RHE ~ 1.8V vs. RHE, the sweep speed was 0.05 V / s, and the measurement temperature was 25 ° C.
Based on the obtained value of the oxidation peak potential, the evaluation was made according to the following criteria. The results are shown in Table 1.
A: Oxidation peak potential is 1.0 V vs. RHE or higher B: Oxidation peak potential is 1.0 V vs. Less than RHE
（評価２：気泡離脱回数）
ビーカー内の水溶液Ｓ１中に光触媒付き基材を置き、キセノン光源（朝日分光、ＭＡＸ－３０３、波長範囲３８５～７４０ｎｍ）を３分間照射した。その間に、デジタルマイクロスコープ（キーエンス、ＶＨＸ－５０００、レンズＶＨ－Ｚ５０Ｌ）を用いて光触媒表面の気泡発生を６ｍｍ×１ｍｍの範囲で観察した。観察可能な気泡の直径は最小１０μｍであった。
観察範囲および時間内における光触媒表面での気泡離脱回数（光触媒付き基材の表面で発生した後に、そこから離れて水中に浮上した気泡の個数）を測定し、純水中の気泡離脱回数に対する水溶液中の気泡離脱回数を比較評価した。なお、気泡離脱回数が多いほど、初期の気体発生量が多いといえる。
評価基準は以下の通りであり、結果を表１に示す。
Ａ：気泡離脱回数が純水と比べて２倍超
Ｂ：気泡離脱回数が純水と比べて１倍超、２倍以下
Ｃ：気泡離脱回数が純水と比べて１倍以下 (Evaluation 2: Number of bubbles detached)
A substrate with a photocatalyst was placed in the aqueous solution S1 in the beaker, and a xenon light source (Asahi spectroscopy, MAX-303, wavelength range 385 to 740 nm) was irradiated for 3 minutes. During that time, the generation of bubbles on the surface of the photocatalyst was observed in the range of 6 mm × 1 mm using a digital microscope (Keyence, VHX-5000, lens VH-Z50L). The minimum observable bubble diameter was 10 μm.
The number of bubbles detached from the surface of the photocatalyst within the observation range and time (the number of bubbles generated on the surface of the photocatalyst substrate and then separated from it and then floated into water) was measured, and the aqueous solution with respect to the number of bubbles detached in pure water. The number of bubbles leaving was compared and evaluated. It can be said that the larger the number of bubbles released, the larger the initial amount of gas generated.
The evaluation criteria are as follows, and the results are shown in Table 1.
A: The number of bubble separations is more than twice that of pure water B: The number of bubble separations is more than 1 times and 2 times or less compared to pure water C: The number of bubble separations is 1 times or less compared to pure water
ビーカー内の水溶液Ｓ１中に光触媒付き基材を置き、キセノン光源（朝日分光、ＭＡＸ－３０３、波長範囲３８５～７４０ｎｍ）を３分間照射した。その間に、デジタルマイクロスコープ（キーエンス、ＶＨＸ－５０００、レンズＶＨ－Ｚ５０Ｌ）を用いて光触媒表面の気泡発生を６ｍｍ×１ｍｍの範囲で観察した。観察可能な気泡の直径は最小１０μｍであった。
観察範囲および時間内における光触媒表面での気泡離脱回数（光触媒付き基材の表面で発生した後に、そこから離れて水中に浮上した気泡の個数）を測定し、純水中の気泡離脱回数に対する水溶液中の気泡離脱回数を比較評価した。なお、気泡離脱回数が多いほど、初期の気体発生量が多いといえる。
評価基準は以下の通りであり、結果を表１に示す。
Ａ：気泡離脱回数が純水と比べて２倍超
Ｂ：気泡離脱回数が純水と比べて１倍超、２倍以下
Ｃ：気泡離脱回数が純水と比べて１倍以下 (Evaluation 2: Number of bubbles detached)
A substrate with a photocatalyst was placed in the aqueous solution S1 in the beaker, and a xenon light source (Asahi spectroscopy, MAX-303, wavelength range 385 to 740 nm) was irradiated for 3 minutes. During that time, the generation of bubbles on the surface of the photocatalyst was observed in the range of 6 mm × 1 mm using a digital microscope (Keyence, VHX-5000, lens VH-Z50L). The minimum observable bubble diameter was 10 μm.
The number of bubbles detached from the surface of the photocatalyst within the observation range and time (the number of bubbles generated on the surface of the photocatalyst substrate and then separated from it and then floated into water) was measured, and the aqueous solution with respect to the number of bubbles detached in pure water. The number of bubbles leaving was compared and evaluated. It can be said that the larger the number of bubbles released, the larger the initial amount of gas generated.
The evaluation criteria are as follows, and the results are shown in Table 1.
A: The number of bubble separations is more than twice that of pure water B: The number of bubble separations is more than 1 times and 2 times or less compared to pure water C: The number of bubble separations is 1 times or less compared to pure water
（評価３：水素発生速度）
自動２連光触媒用閉鎖循環反応システム（幕張理化学硝子製作所、ＰＣＡＴ１３０６５－Ｔ－２９－１）、ガスクロマトグラフ（島津製作所、ＧＣ－８Ａ）、キセノンランプ（イーグルエンジニアリング、Ｒ３００－３Ｊ）、および、反応容器（硼珪酸ガラス製、直径８ｃｍ、高さ１２ｃｍ）を有するガス発生量測定システムを準備した（図２参照）。
図２に示すように、ガス発生量測定システム５００は、水分解装置１００と、自動２連光触媒用閉鎖循環反応システム２００と、キセノンランプ３００と、ガスクロマトグラフ４００と、を有する。水分解装置１００は、水溶液Ｓ１が収容された反応容器１１０と、水溶液Ｓ１に浸漬された光触媒付き基材１２０と、を有する。自動２連光触媒用閉鎖循環反応システム２００は、圧力計２１０と、循環ポンプ２２０と、真空ポンプ２３０と、各部材を接続する配管２４０と、を有する。
具体的には、反応容器１１０の底面に光触媒付き基材１２０を置き、０．１Ｌの水溶液Ｓ１を注いだ。この反応容器１１０を、自動２連光触媒用閉鎖循環反応システム２００に接続して、真空ポンプ２３０による１０Ｐａの減圧下にて１時間脱気を行なった上で、アルゴン（Ａｒ）を導入して１０ｋＰａとした。その後、キセノンランプ３００から光触媒付き基材１２０に光Ｌ１を照射して、ガスクロマトグラフ４００により１時間おきに反応容器１１０内での水素と酸素のガス発生量を測定した。
光照射開始後０～３時間の水素ガス発生量から「水素発生速度」（１時間当たりの水素ガス発生量）を計算して、水素発生速度の「初期値」とした。オクチルフェノールエトキシレート（Ｄｏｗ社、ＴＲＩＴＯＮ（登録商標） Ｘ－１００、ノニオン性界面活性剤）の濃度が１ｍｍｏｌ／Ｌである水溶液（以下、「基準水溶液」ともいう。）の「初期値」に対する、水溶液Ｓ１での「初期値」を比較評価した。
評価基準は以下の通りであり、結果を表１に示す。
Ｓ：水素発生速度の初期値が基準水溶液と比べて４倍超
Ａ：水素発生速度の初期値が基準水溶液と比べて３．５倍超、４倍以下
Ｂ：水素発生速度の初期値が基準水溶液と比べて３．５倍以下 (Evaluation 3: Hydrogen generation rate)
Closed circulation reaction system for automatic double photocatalyst (Makuhari Rikagaku Glass Mfg. Co., Ltd., PCAT13065-T-29-1), gas chromatograph (Shimadzu Mfg. Co., Ltd., GC-8A), xenon lamp (Eagle Engineering, R300-3J), and reaction vessel. A gas generation measurement system (made of borosilicate glass, diameter 8 cm, height 12 cm) was prepared (see FIG. 2).
As shown in FIG. 2, the gas generationamount measuring system 500 includes a water decomposition device 100, a closed circulation reaction system 200 for an automatic double photocatalyst, a xenon lamp 300, and a gas chromatograph 400. The water decomposition apparatus 100 has a reaction vessel 110 containing the aqueous solution S1 and a photocatalytic substrate 120 immersed in the aqueous solution S1. The closed circulation reaction system 200 for an automatic double photocatalyst includes a pressure gauge 210, a circulation pump 220, a vacuum pump 230, and a pipe 240 connecting each member.
Specifically, abase material 120 with a photocatalyst was placed on the bottom surface of the reaction vessel 110, and 0.1 L of the aqueous solution S1 was poured. This reaction vessel 110 is connected to a closed circulation reaction system 200 for an automatic double photocatalyst, degassed under a reduced pressure of 10 Pa by a vacuum pump 230 for 1 hour, and then argon (Ar) is introduced to introduce 10 kPa. And said. Then, the base material 120 with a photocatalyst was irradiated with light L1 from the xenon lamp 300, and the amount of hydrogen and oxygen gas generated in the reaction vessel 110 was measured every hour by the gas chromatograph 400.
The "hydrogen generation rate" (hydrogen gas generation amount per hour) was calculated from the hydrogen gas generation amount 0 to 3 hours after the start of light irradiation, and used as the "initial value" of the hydrogen generation rate. An aqueous solution with respect to the "initial value" of an aqueous solution (hereinafter, also referred to as "reference aqueous solution") having a concentration of octylphenol ethoxylate (Dow, TRITON (registered trademark) X-100, nonionic surfactant) of 1 mmol / L. The "initial value" in S1 was compared and evaluated.
The evaluation criteria are as follows, and the results are shown in Table 1.
S: The initial value of the hydrogen generation rate is more than 4 times that of the reference aqueous solution A: The initial value of the hydrogen generation rate is more than 3.5 times that of the reference aqueous solution and 4 times or less B: The initial value of the hydrogen generation rate is the standard 3.5 times or less compared to aqueous solution
自動２連光触媒用閉鎖循環反応システム（幕張理化学硝子製作所、ＰＣＡＴ１３０６５－Ｔ－２９－１）、ガスクロマトグラフ（島津製作所、ＧＣ－８Ａ）、キセノンランプ（イーグルエンジニアリング、Ｒ３００－３Ｊ）、および、反応容器（硼珪酸ガラス製、直径８ｃｍ、高さ１２ｃｍ）を有するガス発生量測定システムを準備した（図２参照）。
図２に示すように、ガス発生量測定システム５００は、水分解装置１００と、自動２連光触媒用閉鎖循環反応システム２００と、キセノンランプ３００と、ガスクロマトグラフ４００と、を有する。水分解装置１００は、水溶液Ｓ１が収容された反応容器１１０と、水溶液Ｓ１に浸漬された光触媒付き基材１２０と、を有する。自動２連光触媒用閉鎖循環反応システム２００は、圧力計２１０と、循環ポンプ２２０と、真空ポンプ２３０と、各部材を接続する配管２４０と、を有する。
具体的には、反応容器１１０の底面に光触媒付き基材１２０を置き、０．１Ｌの水溶液Ｓ１を注いだ。この反応容器１１０を、自動２連光触媒用閉鎖循環反応システム２００に接続して、真空ポンプ２３０による１０Ｐａの減圧下にて１時間脱気を行なった上で、アルゴン（Ａｒ）を導入して１０ｋＰａとした。その後、キセノンランプ３００から光触媒付き基材１２０に光Ｌ１を照射して、ガスクロマトグラフ４００により１時間おきに反応容器１１０内での水素と酸素のガス発生量を測定した。
光照射開始後０～３時間の水素ガス発生量から「水素発生速度」（１時間当たりの水素ガス発生量）を計算して、水素発生速度の「初期値」とした。オクチルフェノールエトキシレート（Ｄｏｗ社、ＴＲＩＴＯＮ（登録商標） Ｘ－１００、ノニオン性界面活性剤）の濃度が１ｍｍｏｌ／Ｌである水溶液（以下、「基準水溶液」ともいう。）の「初期値」に対する、水溶液Ｓ１での「初期値」を比較評価した。
評価基準は以下の通りであり、結果を表１に示す。
Ｓ：水素発生速度の初期値が基準水溶液と比べて４倍超
Ａ：水素発生速度の初期値が基準水溶液と比べて３．５倍超、４倍以下
Ｂ：水素発生速度の初期値が基準水溶液と比べて３．５倍以下 (Evaluation 3: Hydrogen generation rate)
Closed circulation reaction system for automatic double photocatalyst (Makuhari Rikagaku Glass Mfg. Co., Ltd., PCAT13065-T-29-1), gas chromatograph (Shimadzu Mfg. Co., Ltd., GC-8A), xenon lamp (Eagle Engineering, R300-3J), and reaction vessel. A gas generation measurement system (made of borosilicate glass, diameter 8 cm, height 12 cm) was prepared (see FIG. 2).
As shown in FIG. 2, the gas generation
Specifically, a
The "hydrogen generation rate" (hydrogen gas generation amount per hour) was calculated from the hydrogen gas generation amount 0 to 3 hours after the start of light irradiation, and used as the "initial value" of the hydrogen generation rate. An aqueous solution with respect to the "initial value" of an aqueous solution (hereinafter, also referred to as "reference aqueous solution") having a concentration of octylphenol ethoxylate (Dow, TRITON (registered trademark) X-100, nonionic surfactant) of 1 mmol / L. The "initial value" in S1 was compared and evaluated.
The evaluation criteria are as follows, and the results are shown in Table 1.
S: The initial value of the hydrogen generation rate is more than 4 times that of the reference aqueous solution A: The initial value of the hydrogen generation rate is more than 3.5 times that of the reference aqueous solution and 4 times or less B: The initial value of the hydrogen generation rate is the standard 3.5 times or less compared to aqueous solution
（評価４：水素発生速度の経過値）
光照射開始後１２～１５時間の水素ガス発生量から「水素発生速度」（１時間当たりの水素ガス発生量）を計算し、これを水素発生速度の「経過値」とした。なお、水素ガス発生量は、評価３と同様の手順により測定した。
水溶液Ｓ１において、「初期値」に対する「経過値」を比較評価した。
Ａ：水素発生速度の経過値が初期値と比べて０．５０倍超
Ｂ：水素発生速度の経過値が初期値と比べて０．５０倍以下 (Evaluation 4: Elapsed value of hydrogen generation rate)
The "hydrogen generation rate" (hydrogen gas generation amount per hour) was calculated from the hydrogen gas generation amount 12 to 15 hours after the start of light irradiation, and this was used as the "elapsed value" of the hydrogen generation rate. The amount of hydrogen gas generated was measured by the same procedure as in Evaluation 3.
In the aqueous solution S1, the "elapsed value" with respect to the "initial value" was compared and evaluated.
A: The elapsed value of the hydrogen generation rate is more than 0.50 times the initial value. B: The elapsed value of the hydrogen generation rate is 0.50 times or less compared to the initial value.
光照射開始後１２～１５時間の水素ガス発生量から「水素発生速度」（１時間当たりの水素ガス発生量）を計算し、これを水素発生速度の「経過値」とした。なお、水素ガス発生量は、評価３と同様の手順により測定した。
水溶液Ｓ１において、「初期値」に対する「経過値」を比較評価した。
Ａ：水素発生速度の経過値が初期値と比べて０．５０倍超
Ｂ：水素発生速度の経過値が初期値と比べて０．５０倍以下 (Evaluation 4: Elapsed value of hydrogen generation rate)
The "hydrogen generation rate" (hydrogen gas generation amount per hour) was calculated from the hydrogen gas generation amount 12 to 15 hours after the start of light irradiation, and this was used as the "elapsed value" of the hydrogen generation rate. The amount of hydrogen gas generated was measured by the same procedure as in Evaluation 3.
In the aqueous solution S1, the "elapsed value" with respect to the "initial value" was compared and evaluated.
A: The elapsed value of the hydrogen generation rate is more than 0.50 times the initial value. B: The elapsed value of the hydrogen generation rate is 0.50 times or less compared to the initial value.
［実施例２～１１］
水溶液Ｓ１の代わりに、表１の水溶液Ｓ２～Ｓ１１を用いた以外は、実施例１と同様にして、各種評価を行った。結果を表１に示す。
なお、各水溶液に含まれる界面活性剤の概要を以下に示す。
また、表面張力計（協和界面科学社製）を用いた上述の方法にしたがって、各界面活性剤の臨界ミセル濃度（ＣＭＣ）を算出した。各界面活性剤のＣＭＣに基づいて、各水溶液中の界面活性剤の濃度が、各水溶液中に含まれる界面活性剤のＣＭＣに対して何倍であるかを、表１の界面活性剤の濃度の欄に示した。 [Examples 2 to 11]
Various evaluations were performed in the same manner as in Example 1 except that the aqueous solutions S2 to S11 in Table 1 were used instead of the aqueous solution S1. The results are shown in Table 1.
The outline of the surfactant contained in each aqueous solution is shown below.
In addition, the critical micelle concentration (CMC) of each surfactant was calculated according to the above-mentioned method using a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd.). Based on the CMC of each surfactant, the concentration of the surfactant in each aqueous solution is determined by how many times the concentration of the surfactant contained in each aqueous solution is compared with the CMC of the surfactant in Table 1. Shown in the column.
水溶液Ｓ１の代わりに、表１の水溶液Ｓ２～Ｓ１１を用いた以外は、実施例１と同様にして、各種評価を行った。結果を表１に示す。
なお、各水溶液に含まれる界面活性剤の概要を以下に示す。
また、表面張力計（協和界面科学社製）を用いた上述の方法にしたがって、各界面活性剤の臨界ミセル濃度（ＣＭＣ）を算出した。各界面活性剤のＣＭＣに基づいて、各水溶液中の界面活性剤の濃度が、各水溶液中に含まれる界面活性剤のＣＭＣに対して何倍であるかを、表１の界面活性剤の濃度の欄に示した。 [Examples 2 to 11]
Various evaluations were performed in the same manner as in Example 1 except that the aqueous solutions S2 to S11 in Table 1 were used instead of the aqueous solution S1. The results are shown in Table 1.
The outline of the surfactant contained in each aqueous solution is shown below.
In addition, the critical micelle concentration (CMC) of each surfactant was calculated according to the above-mentioned method using a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd.). Based on the CMC of each surfactant, the concentration of the surfactant in each aqueous solution is determined by how many times the concentration of the surfactant contained in each aqueous solution is compared with the CMC of the surfactant in Table 1. Shown in the column.
・臭化ドデシルトリメチルアンモニウム（カチオン性界面活性剤。下記式Ｉ－１参照。）
・臭化ヘキサデシルトリメチルアンモニウム（カチオン性界面活性剤。下記式Ｉ－２参照。）
・臭化テトラメチルアンモニウム（カチオン性界面活性剤。下記式ＩＩ－１参照。）
・ベンジルドデシルジメチルアンモニウムブロミド（カチオン性界面活性剤。下記式ＩＩ－２参照。）
・塩化ベンゼトニウム（カチオン性界面活性剤。下記式ＩＩ－３参照。）
・ラウリルスルホベタイン（両性界面活性剤。下記式ＩＩＩ－１参照。）
・ドデシル硫酸ナトリウム（アニオン性界面活性剤。下記式ＩＶ－１参照。）
・デカンスルホン酸ナトリウム（アニオン性界面活性剤。下記式ＩＶ－２参照。）
・オクチルフェノールエトキシレート（ノニオン性界面活性剤。下記式Ｖ－１参照。式中、ｎ＝９．５。商品名「ＴＲＩＴＯＮ（登録商標） Ｘ－１００」、Ｄｏｗ社製）
・オクタエチレングリコールモノドデシルエーテル（ノニオン性界面活性剤。下記式Ｖ－２参照。） -Dodecyltrimethylammonium bromide (cationic surfactant. See formula I-1 below.)
-Hexadecyltrimethylammonium bromide (cationic surfactant. See formula I-2 below.)
-Tetramethylammonium bromide (cationic surfactant. See formula II-1 below.)
-Benzyldodecyldimethylammonium bromide (cationic surfactant. See formula II-2 below.)
-Benzethonium chloride (cationic surfactant. See formula II-3 below.)
-Lauryl sulfobetaine (amphoteric surfactant. See formula III-1 below.)
-Sodium dodecyl sulfate (anionic surfactant. See formula IV-1 below.)
-Sodium decane sulfonate (anionic surfactant. See formula IV-2 below.)
Octylphenol ethoxylate (nonionic surfactant. See formula V-1 below. In formula, n = 9.5. Trade name "TRITON (registered trademark) X-100", manufactured by Dow)
-Octaethylene glycol monododecyl ether (nonionic surfactant. See formula V-2 below.)
・臭化ヘキサデシルトリメチルアンモニウム（カチオン性界面活性剤。下記式Ｉ－２参照。）
・臭化テトラメチルアンモニウム（カチオン性界面活性剤。下記式ＩＩ－１参照。）
・ベンジルドデシルジメチルアンモニウムブロミド（カチオン性界面活性剤。下記式ＩＩ－２参照。）
・塩化ベンゼトニウム（カチオン性界面活性剤。下記式ＩＩ－３参照。）
・ラウリルスルホベタイン（両性界面活性剤。下記式ＩＩＩ－１参照。）
・ドデシル硫酸ナトリウム（アニオン性界面活性剤。下記式ＩＶ－１参照。）
・デカンスルホン酸ナトリウム（アニオン性界面活性剤。下記式ＩＶ－２参照。）
・オクチルフェノールエトキシレート（ノニオン性界面活性剤。下記式Ｖ－１参照。式中、ｎ＝９．５。商品名「ＴＲＩＴＯＮ（登録商標） Ｘ－１００」、Ｄｏｗ社製）
・オクタエチレングリコールモノドデシルエーテル（ノニオン性界面活性剤。下記式Ｖ－２参照。） -Dodecyltrimethylammonium bromide (cationic surfactant. See formula I-1 below.)
-Hexadecyltrimethylammonium bromide (cationic surfactant. See formula I-2 below.)
-Tetramethylammonium bromide (cationic surfactant. See formula II-1 below.)
-Benzyldodecyldimethylammonium bromide (cationic surfactant. See formula II-2 below.)
-Benzethonium chloride (cationic surfactant. See formula II-3 below.)
-Lauryl sulfobetaine (amphoteric surfactant. See formula III-1 below.)
-Sodium dodecyl sulfate (anionic surfactant. See formula IV-1 below.)
-Sodium decane sulfonate (anionic surfactant. See formula IV-2 below.)
Octylphenol ethoxylate (nonionic surfactant. See formula V-1 below. In formula, n = 9.5. Trade name "TRITON (registered trademark) X-100", manufactured by Dow)
-Octaethylene glycol monododecyl ether (nonionic surfactant. See formula V-2 below.)
表１に示すように、水の代わりに界面活性剤を含む水溶液を用いて水分解を実施した場合、評価２（気泡離脱回数）の評価結果が優れる結果が得られた（実施例１～１１）。このことから、界面活性剤を含む水溶液を用いた場合、水を用いた場合と比較して、初期の気体発生量に優れるといえる。
実施例１～１１の対比から、水溶液の酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ以上であること、および、界面活性剤が芳香環を有しないこと、を満たす場合（実施例１～４、８～９、１１）、評価２（気泡離脱回数）の評価結果が特に優れる結果が得られた。
実施例１～１１の対比から、水溶液の酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ以上であること、界面活性剤が芳香環、ヒドロキシ基、アルコキシ基、および、エーテル結合を有しないこと、を満たす場合（実施例１～４および８～９）、水素発生速度に優れることが示された（評価３参照）。
実施例１～１１の対比から、上記式Ｉを満たす界面活性剤を用いた場合（実施例１～３）、水素発生速度の経過値が優れることが示された（評価４参照）。 As shown in Table 1, when water decomposition was carried out using an aqueous solution containing a surfactant instead of water, excellent evaluation results of Evaluation 2 (number of bubble separations) were obtained (Examples 1 to 11). ). From this, it can be said that when an aqueous solution containing a surfactant is used, the initial amount of gas generated is superior to that when water is used.
From the comparison of Examples 1 to 11, the oxidation peak potential of the aqueous solution was 1.0 V vs. When the condition is RHE or higher and the surfactant does not have an aromatic ring (Examples 1 to 4, 8 to 9, 11), the evaluation result of evaluation 2 (number of bubble separations) is particularly excellent. was gotten.
From the comparison of Examples 1 to 11, the oxidation peak potential of the aqueous solution was 1.0 V vs. When the condition is RHE or higher and the surfactant does not have an aromatic ring, a hydroxy group, an alkoxy group, and an ether bond (Examples 1 to 4 and 8 to 9), the hydrogen generation rate is excellent. Shown (see evaluation 3).
From the comparison of Examples 1 to 11, it was shown that the elapsed value of the hydrogen generation rate was excellent when the surfactant satisfying the above formula I was used (Examples 1 to 3) (see Evaluation 4).
実施例１～１１の対比から、水溶液の酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ以上であること、および、界面活性剤が芳香環を有しないこと、を満たす場合（実施例１～４、８～９、１１）、評価２（気泡離脱回数）の評価結果が特に優れる結果が得られた。
実施例１～１１の対比から、水溶液の酸化ピーク電位が１．０Ｖ ｖｓ．ＲＨＥ以上であること、界面活性剤が芳香環、ヒドロキシ基、アルコキシ基、および、エーテル結合を有しないこと、を満たす場合（実施例１～４および８～９）、水素発生速度に優れることが示された（評価３参照）。
実施例１～１１の対比から、上記式Ｉを満たす界面活性剤を用いた場合（実施例１～３）、水素発生速度の経過値が優れることが示された（評価４参照）。 As shown in Table 1, when water decomposition was carried out using an aqueous solution containing a surfactant instead of water, excellent evaluation results of Evaluation 2 (number of bubble separations) were obtained (Examples 1 to 11). ). From this, it can be said that when an aqueous solution containing a surfactant is used, the initial amount of gas generated is superior to that when water is used.
From the comparison of Examples 1 to 11, the oxidation peak potential of the aqueous solution was 1.0 V vs. When the condition is RHE or higher and the surfactant does not have an aromatic ring (Examples 1 to 4, 8 to 9, 11), the evaluation result of evaluation 2 (number of bubble separations) is particularly excellent. was gotten.
From the comparison of Examples 1 to 11, the oxidation peak potential of the aqueous solution was 1.0 V vs. When the condition is RHE or higher and the surfactant does not have an aromatic ring, a hydroxy group, an alkoxy group, and an ether bond (Examples 1 to 4 and 8 to 9), the hydrogen generation rate is excellent. Shown (see evaluation 3).
From the comparison of Examples 1 to 11, it was shown that the elapsed value of the hydrogen generation rate was excellent when the surfactant satisfying the above formula I was used (Examples 1 to 3) (see Evaluation 4).
１ 水分解装置
１０ 容器
２０ 光触媒付き基材
２２ 基材
２４ 光触媒
Ｓ 水溶液
Ｌ 光
１００ 水分解装置
１１０ 反応容器
１２０ 光触媒付き基材
２００ 自動２連光触媒用閉鎖循環反応システム
２１０ 圧力計
２２０ 循環ポンプ
２３０ 真空ポンプ
２４０ 配管
３００ キセノンランプ
４００ ガスクロマトグラフ
５００ ガス発生量測定システム
Ｓ１ 水溶液
Ｌ１ 光 1Water decomposition device 10 Container 20 Base material with photocatalyst 22 Base material 24 Photocatalyst S aqueous solution L Optical 100 Water decomposition device 110 Reaction container 120 Base material with photocatalyst 200 Closed circulation reaction system for automatic double photocatalyst 210 Pressure gauge 220 Circulation pump 230 Vacuum Pump 240 Piping 300 Xenon lamp 400 Gas chromatograph 500 Gas generation measurement system S1 Aqueous solution L1 Light
１０ 容器
２０ 光触媒付き基材
２２ 基材
２４ 光触媒
Ｓ 水溶液
Ｌ 光
１００ 水分解装置
１１０ 反応容器
１２０ 光触媒付き基材
２００ 自動２連光触媒用閉鎖循環反応システム
２１０ 圧力計
２２０ 循環ポンプ
２３０ 真空ポンプ
２４０ 配管
３００ キセノンランプ
４００ ガスクロマトグラフ
５００ ガス発生量測定システム
Ｓ１ 水溶液
Ｌ１ 光 1
Claims (9)
- 界面活性剤を含む水溶液が収容された容器と、
前記水溶液中に浸漬されており、基材および前記基材上に固定された光触媒を有する光触媒付き基材、または、前記容器の内壁面上に固定された光触媒と、を有し、
前記光触媒に光を照射することによって、前記光触媒から気体を発生させる、水分解装置。 A container containing an aqueous solution containing a surfactant,
It has a base material and a photocatalyst-attached base material having a photocatalyst fixed on the base material, or a photocatalyst fixed on the inner wall surface of the container, which is immersed in the aqueous solution.
A water decomposition device that generates a gas from the photocatalyst by irradiating the photocatalyst with light. - サイクリックボルタンメトリー法によって前記水溶液の酸化ピーク電位を求めた場合、前記水溶液の酸化ピーク電位が、１．０Ｖ ｖｓ．ＲＨＥ以上である、請求項１に記載の水分解装置。 When the oxidation peak potential of the aqueous solution was determined by the cyclic voltammetry method, the oxidation peak potential of the aqueous solution was 1.0 V vs. The water splitting apparatus according to claim 1, which is RHE or higher.
- 前記界面活性剤が、芳香環を有しない、請求項１または２に記載の水分解装置。 The water decomposition apparatus according to claim 1 or 2, wherein the surfactant does not have an aromatic ring.
- 前記界面活性剤が、ヒドロキシ基、アルコキシ基、および、エーテル結合を有しない、請求項１～３のいずれか１項に記載の水分解装置。 The water splitting apparatus according to any one of claims 1 to 3, wherein the surfactant does not have a hydroxy group, an alkoxy group, and an ether bond.
- 前記界面活性剤が式Ｉで表される化合物を含む、請求項１～４のいずれか１項に記載の水分解装置。
- 前記光触媒が、酸化物、酸窒化物、窒化物およびカルコゲナイド化合物からなる群から選択される少なくとも一種の光触媒化合物を含み、
前記光触媒化合物が、Ｓｒ、Ｎａ、Ｍｇ、Ａｌ、Ｓｉ、Ｃａ、Ｔｉ、Ｖ、Ｆｅ、Ｃｕ、Ｚｎ、Ｇａ、Ｙ、Ｚｒ、Ｎｂ、Ａｇ、Ｉｎ、Ｓｎ、Ｂａ、Ｌａ、Ｔａ、ＷおよびＢｉからなる群より選択される少なくとも１種の元素を含む、請求項１～５のいずれか１項に記載の水分解装置。 The photocatalyst comprises at least one photocatalytic compound selected from the group consisting of oxides, oxynitrides, nitrides and chalcogenide compounds.
The photocatalytic compounds are Sr, Na, Mg, Al, Si, Ca, Ti, V, Fe, Cu, Zn, Ga, Y, Zr, Nb, Ag, In, Sn, Ba, La, Ta, W and Bi. The water splitting apparatus according to any one of claims 1 to 5, which comprises at least one element selected from the group consisting of. - 前記光触媒が、水素発生用光触媒化合物および酸素発生用光触媒化合物の両方を含む、請求項１～６のいずれか１項に記載の水分解装置。 The water decomposition apparatus according to any one of claims 1 to 6, wherein the photocatalyst contains both a photocatalyst compound for hydrogen generation and a photocatalyst compound for oxygen generation.
- 前記光触媒が、Ｎａ、Ａｌ、Ｃｒ、Ｎｉ、Ｒｈ、ＳｂおよびＴａからなる群から選択される少なくとも１種の元素をドープしたＳｒＴｉＯ３を含む、請求項１～７のいずれか１項に記載の水分解装置。 The one according to any one of claims 1 to 7, wherein the photocatalyst comprises SrTiO 3 doped with at least one element selected from the group consisting of Na, Al, Cr, Ni, Rh, Sb and Ta. Water decomposition device.
- 請求項１～８のいずれか１項に記載の水分解装置を用いた気体の製造方法であって、
前記水分解装置が有する光触媒に光を照射することによって、前記光触媒の表面から気体を発生させる、気体の製造方法。 A method for producing a gas using the water splitting apparatus according to any one of claims 1 to 8.
A method for producing a gas, in which a gas is generated from the surface of the photocatalyst by irradiating the photocatalyst included in the water splitting device with light.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4394293A (en) * | 1979-09-08 | 1983-07-19 | Engelhard Corporation | Catalyst for the photolytic production of hydrogen from water |
| JP2006306667A (en) * | 2005-04-28 | 2006-11-09 | Hamamatsu Photonics Kk | Hydrogen generator and ice crusher |
| JP2013237587A (en) * | 2012-05-15 | 2013-11-28 | Toyota Motor Corp | Hydrogen generating device using photocatalyst |
| JP2017124393A (en) * | 2015-07-31 | 2017-07-20 | Toto株式会社 | Photocatalytic material and manufacturing method therefor |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4394293A (en) * | 1979-09-08 | 1983-07-19 | Engelhard Corporation | Catalyst for the photolytic production of hydrogen from water |
| JP2006306667A (en) * | 2005-04-28 | 2006-11-09 | Hamamatsu Photonics Kk | Hydrogen generator and ice crusher |
| JP2013237587A (en) * | 2012-05-15 | 2013-11-28 | Toyota Motor Corp | Hydrogen generating device using photocatalyst |
| JP2017124393A (en) * | 2015-07-31 | 2017-07-20 | Toto株式会社 | Photocatalytic material and manufacturing method therefor |
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