Composition for forming diamond electrode, method for manufacturing diamond electrode, diamond electrode, electrolytic treatment apparatus, and ozone generator

Abstract

To provide a composition for forming a diamond electrode which can simply form an electrode layer containing conductive diamond particles on base materials having various shapes, a method for manufacturing a diamond electrode using the composition for forming the diamond electrode, a diamond electrode capable of being manufactured using the composition for forming the diamond electrode, and an electrolytic treatment apparatus and an ozone generator which include the diamond electrode.SOLUTION: A composition for forming a diamond electrode contains conductive diamond particles, a binder resin, and a solvent, wherein the content of the binder resin is 1 to 10 pts.mass with respect to 1 pt.mass of the content of the conductive diamond particles.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composition for forming a diamond electrode, a method for manufacturing a diamond electrode, a diamond electrode, an electrolytic treatment device, and an ozone generation device. [Background technology]

[0002] Ozone is a substance with extremely strong oxidizing power and is used for a wide range of purposes, including sterilization and deodorization in water supply and sewerage facilities.

[0003] The main methods for generating ozone are the ultraviolet lamp method, the silent discharge method, and the electrolysis method. Among these, the electrolysis method involves applying a direct current voltage between the anode and cathode of an electrolysis cell to electrolyze water, thereby generating ozone and oxygen simultaneously on the anode side. The use of a so-called zero-gap cell, in which the anode and cathode are in close contact with a solid polymer electrolyte membrane, enables direct electrolysis of pure water. In general, zero-gap cells use electrodes that are porous or have multiple through-holes to allow the generated gas to pass through.

[0004] Conventionally, lead dioxide electrodes, in which a lead dioxide layer (electrode layer) is formed on a porous metal substrate by electrolytic plating or the like, have been used as anodes when generating ozone by electrolysis. However, lead dioxide has the problem of being environmentally hazardous and easily reduced by reaction with reducing substances such as hydrogen remaining in the electrolytic cell. Therefore, in recent years, the use of diamond electrodes instead of lead dioxide electrodes has been proposed. For example, Non-Patent Document 1 reports the use of a diamond electrode in which multiple through-holes are formed by laser processing in a conductive diamond substrate produced by chemical vapor deposition (CVD). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] K. Arihara et al., J. Electrochem. Soc., 154, E71 (2007) Summary of the Invention [Problem to be solved by the invention]

[0006] However, the diamond electrode described in Non-Patent Document 1 requires a conductive diamond substrate to be obtained by CVD, and then multiple through-holes to be formed by laser processing, making the manufacturing method complicated. In this regard, it is also possible to form a conductive diamond layer (electrode layer) by CVD on a substrate having multiple through-holes. However, with the CVD method, it is difficult to form a conductive diamond layer on the inner surfaces of the through-holes, and there are limitations on the electrode shapes that can be manufactured.

[0007] Therefore, an object of the present invention is to provide a diamond electrode-forming composition that can easily form an electrode layer containing conductive diamond particles on substrates of various shapes, a method for manufacturing a diamond electrode using the diamond electrode-forming composition, a diamond electrode that can be manufactured using the diamond electrode-forming composition, and an electrolytic treatment device and an ozone generation device that include the diamond electrode. [Means for solving the problem]

[0008] Specific means for solving the above problems include the following embodiments. <1> The conductive diamond particles, the binder resin, and the solvent are contained, A diamond electrode-forming composition in which the content of the binder resin is 1 to 10 parts by mass per 1 part by mass of the content of the conductive diamond particles. <2> Further containing a conductive aid, <1> The diamond electrode forming composition according to claim 1. <3> The binder resin includes polyvinylidene fluoride. <1> or <2> The diamond electrode forming composition according to claim 1.

[0009] <4> For the base material <1> ~ <3> 10. A method for manufacturing a diamond electrode, comprising the steps of applying the diamond electrode-forming composition according to any one of claims 1 to 9 and performing a heat treatment to form an electrode layer on the surface of the substrate. <5> the substrate is a planar substrate having a plurality of through holes, The diamond electrode forming composition is applied to the main surface of the planar substrate and the inner surface of the through hole. <4> A method for manufacturing a diamond electrode according to claim 1. <6> The substrate is a metal mesh, an expanded metal, a rolled lath, or a punched metal. <5> A method for manufacturing a diamond electrode according to claim 1.

[0010] <7> a planar substrate having a plurality of through holes; and an electrode layer containing conductive diamond particles and a binder resin, the electrode layer being formed on a main surface of the planar substrate and on the inner surfaces of the through holes; A diamond electrode, wherein the content of the binder resin in the electrode layer is 1 to 10 parts by mass per 1 part by mass of the content of the conductive diamond particles. <8> The binder resin includes polyvinylidene fluoride. <7> The diamond electrode according to claim 1. <9> an electrolytic cell; <7> or <8> An electrolytic treatment apparatus comprising an anode which is the diamond electrode according to claim 1 and a cathode. <10> an electrolytic cell; <7> or <8> An ozone generating device comprising an anode which is the diamond electrode according to claim 1 and a cathode. <11> a solid polymer electrolyte membrane separating the anode and the cathode; The anode is in close contact with one surface of the solid polymer electrolyte membrane, and the cathode is in close contact with the other surface of the solid polymer electrolyte membrane. <10> The ozone generating device according to claim 1. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a diamond electrode-forming composition that can easily form an electrode layer containing conductive diamond particles on substrates of various shapes, a method for manufacturing a diamond electrode using the diamond electrode-forming composition, a diamond electrode that can be manufactured using the diamond electrode-forming composition, and an electrolytic treatment device and an ozone generation device that include the diamond electrode. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing an example of a schematic configuration of an ozone generator equipped with a diamond electrode. [Figure 2] FIG. 1 shows a cyclic voltammogram of an electrolytic cell with diamond electrodes. [Figure 3] FIG. 1 is a graph showing the change in current value over time when constant-voltage electrolysis of ultrapure water was performed using an electrolytic cell equipped with diamond electrodes. DETAILED DESCRIPTION OF THE INVENTION

[0013] Specific embodiments to which the present invention is applied will be described below. In this specification, unless otherwise specified, the expression "x to y" using numerical values ​​x and y means "greater than or equal to x and less than or equal to y." In such expressions, when a unit is assigned only to the numerical value y, the unit is also applied to the numerical value x.

[0014] <Diamond electrode forming composition> The diamond electrode forming composition according to this embodiment contains conductive diamond particles, a binder resin, and a solvent, and the content of the binder resin is 1 to 10 parts by mass relative to 1 part by mass of the conductive diamond particles. Below, each component contained in the diamond electrode forming composition according to this embodiment will be explained. Each component explained below may be used alone or in combination of two or more types.

[0015] [Conductive diamond particles] As the conductive diamond, diamond that is doped with an element of group 13 or group 15 to give conductivity can be mentioned.The conductivity of conductive diamond particles is, for example, 0.01S / cm or more.As the element of group 13 or group 15, for example, boron, nitrogen, phosphorus etc. can be mentioned.Among conductive diamond particles, boron-doped diamond particles (BDDP) that are doped with boron are preferred because of their low electrical resistance.

[0016] The method for producing BDDP is not particularly limited, and known production methods such as those described in Japanese Patent Application Laid-Open No. 2008-36631 and Japanese Patent Application Laid-Open No. 2018-76216 can be used. A preferred production method is to form a boron-doped diamond layer (BDD layer) on the surface of a particulate substrate. This production method will be described below.

[0017] The particulate substrate is not particularly limited as long as it does not melt or deform during the formation of the BDD layer, and can be appropriately selected according to the purpose.The particulate substrate can be, for example, natural or artificial diamond particles; silicon particles; metal particles such as molybdenum particles; metal oxide particles such as alumina particles; boron nitride particles, quartz particles; etc.Among these, natural or artificial diamond particles are preferred.

[0018] The method for forming the BDD layer is not particularly limited and can be appropriately selected depending on the purpose. Examples of the method for forming the BDD layer include CVD methods such as microwave plasma CVD and hot filament CVD; physical vapor deposition (PVD) methods such as ion beam deposition and ionization deposition; and high-temperature and high-pressure methods. Among these, microwave plasma CVD is preferred.

[0019] In the CVD method described above, the carbon and boron sources used as raw materials for the BDD layer are not particularly limited. Examples of carbon sources include aliphatic hydrocarbons such as methane, ethane, propane, butane, pentane, hexane, heptane, and octane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; alcohols such as methanol, ethanol, isopropyl alcohol, and butanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran, and dioxane; and esters such as methyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate. Examples of boron sources include boron oxide, boron carbide, boron nitride, boric acid, diborane, triethylborane, trimethoxyborane, triethoxyborane, tripropoxyborane, and tri(1,1-dimethylethoxy)borane.

[0020] In the BDD layer, the number of boron atoms doped into the diamond is preferably 10 to 100,000 ppm, more preferably 100 to 50,000 ppm, and even more preferably 1,000 to 30,000 ppm, relative to the number of carbon atoms constituting the diamond.

[0021] The shape of the conductive diamond particles is not particularly limited, and examples thereof include spherical, polyhedral, needle-like, and spindle-like shapes.

[0022] The average particle size of the conductive diamond particles is preferably 5 nm to 100 μm, more preferably 50 nm to 10 μm, and even more preferably 100 nm to 1 μm. The average particle size of the conductive diamond particles is the volume average particle size measured by dynamic light scattering (DLS).

[0023] The conductive diamond particles may be surface-treated with a silane coupling agent as needed, which tends to improve dispersibility in the composition.

[0024] Examples of silane coupling agents include vinyltriethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

[0025] The surface treatment method using the silane coupling agent is not particularly limited, and any method can be adopted.One example is a method in which conductive diamond particles and a silane coupling agent are added to an alcohol-based solvent, and then mixed using an ultrasonic homogenizer or the like to perform surface treatment, and then the conductive diamond particles after surface treatment are taken out by centrifugation, decantation, or the like.

[0026] The content of conductive diamond particles in the diamond electrode forming composition according to this embodiment is preferably 0.5 to 30 mass %, more preferably 1 to 10 mass %, and even more preferably 1.5 to 4 mass %.

[0027] [Binder resin] Examples of binder resins include fluorine-based resins such as polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), and polytetrafluoroethylene (PTFE); hydrocarbon resins such as polyethylene, polypropylene, styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (HSBR), butylene rubber, acrylonitrile-butadiene rubber, polybutadiene, and polyisoprene; acrylic resins, vinyl resins, styrene resins, amide resins, imide resins, urethane resins, urea resins, polyester resins, polyether resins, phenolic resins, epoxy resins, polycarbonate resins, and silicone resins. Among these, fluorine-based resins are preferred, and polyvinylidene fluoride is more preferred, from the viewpoints of adhesion to the substrate and oxidation resistance.

[0028] The mass average molecular weight of the binder resin is 1.0 x 103 ~5.0×10 7 Preferably, it is 1.0 × 10 4 ~5.0×10 6 More preferably, it is 1.0 × 10 5 ~5.0×10 5 It is more preferable that the weight average molecular weight of the binder resin is: The weight average molecular weight of the binder resin can be measured as a polystyrene-equivalent molecular weight using gel permeation chromatography (GPC).

[0029] The content of binder resin in the diamond electrode-forming composition according to this embodiment is 1 to 10 parts by mass, preferably 2 to 8 parts by mass, and more preferably 3 to 5 parts by mass, per 1 part by mass of the conductive diamond particles. By making the content of binder resin 1 part by mass or more, adhesion to the substrate tends to be improved. Furthermore, by making the content of binder resin 10 parts by mass or less, a decrease in conductivity tends to be suppressed.

[0030] [solvent] Examples of the solvent include alcoholic solvents such as methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, polyethylene glycol, glycerin, 1,4-butanediol, 1,6-hexanediol, cyclohexanediol, sorbitol, and xylitol; ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, and tetrahydrofuran. ether-based solvents such as ethanol and dioxane; ester-based solvents such as ethyl acetate, butyl acetate, propyl acetate, and butyl butyrate; amide-based solvents such as N,N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, 2-pyrrolidinone, ε-caprolactam, formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropanamide; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aliphatic hydrocarbon-based solvents such as hexane, heptane, octane, and decane; aromatic hydrocarbon-based solvents such as benzene, toluene, and xylene; and nitrile-based solvents such as acetonitrile, propylonitrile, and isobutyronitrile.

[0031] The content of the solvent in the diamond electrode forming composition according to this embodiment is preferably 50 to 98 mass %, more preferably 70 to 95 mass %, and even more preferably 80 to 90 mass %.

[0032] [Conductive additive] The diamond electrode forming composition according to this embodiment can contain conductive auxiliary agent in order to improve the conductivity of diamond electrode.As conductive auxiliary agent, for example, graphite such as natural graphite, artificial graphite, etc.; carbon black such as acetylene black, ketjen black, furnace black, etc.; carbon fiber such as vapor-grown carbon fiber, carbon nanotube, etc.; metal particle such as copper particle, nickel particle, etc.; conductive polymer such as polyaniline, polypyrrole, polythiophene, polyacetylene, polyphenylene derivative, etc.; zinc oxide, tin oxide, indium tin oxide, niobium-doped titanium oxide, titanium nitride, titanium carbide, etc. conductive metal oxide, metal nitride or metal carbide, etc.; etc.

[0033] When the diamond electrode forming composition according to this embodiment contains a conductive additive, the content thereof is preferably 1 to 30 parts by mass, more preferably 3 to 20 parts by mass, and even more preferably 5 to 15 parts by mass, per 100 parts by mass of the conductive diamond particles.

[0034] <Diamond electrode and its manufacturing method> The diamond electrode of this embodiment has a substrate and an electrode layer formed on the surface of the substrate, the electrode layer containing conductive diamond particles and a binder resin, and the content of the binder resin in the electrode layer is 1 to 10 parts by mass per 1 part by mass of the conductive diamond particles.

[0035] [Base material] The substrate is preferably one having excellent corrosion resistance. Examples of the substrate material include metals such as titanium, tantalum, niobium, zirconium, and platinum; semiconductors such as silicon; and ceramics. The substrate may be a composite substrate made up of multiple substrates made of different materials.

[0036] The shape of the substrate is not particularly limited, and may be planar or may have a special three-dimensional shape such as a curved shape, a cylindrical shape, a stepped shape, a spiral shape, etc. The planar substrate may have a flat main surface, or the main surface may have irregularities, grooves, etc. Furthermore, the substrate may be porous, and a plurality of through-holes may be formed in the main surface of the substrate.

[0037] When diamond electrode is used as the anode of the ozone generating device described later, the substrate is preferably a planar substrate having a plurality of through holes.Such planar substrates include, for example, metal substrates such as metal mesh, expanded metal, rolled lath, punched metal, etc.The thickness of the planar substrate having a plurality of through holes is preferably, for example, 0.1 to 1.0 mm.In addition, the maximum diameter of each through hole when the planar substrate having a plurality of through holes is viewed from above is preferably such that the through hole is not blocked after the diamond electrode forming composition is applied, for example, preferably 1.0 to 5.0 mm.

[0038] The substrate may be roughened by a known method such as blasting or etching in order to enhance adhesion to a layer formed on the substrate.

[0039] [Electrode layer] The electrode layer can be formed by applying the diamond electrode forming composition according to this embodiment to a substrate and then performing a heat treatment.

[0040] The coating method of the diamond electrode forming composition is not particularly limited, and can be suitably selected according to the shape of substrate.Coating method can be, for example, brush coating, dip coating, spray coating, spin coating, roll coating, doctor blade method, gravure coating, screen printing etc.When using a planar substrate with a plurality of through holes, as coating method, preferably, the method that forms electrode layer on the main surface of planar substrate and the inner surface of through holes, and is unlikely to cause the clogging of through holes, for example, brush coating, dip coating etc.

[0041] After applying the diamond electrode-forming composition, a heat treatment is carried out. This heat treatment removes the solvent in the composition, and also increases the strength of the electrode layer, tending to improve adhesion to the substrate. The heat treatment temperature is preferably 50 to 300°C, more preferably 80 to 220°C. The heat treatment time is preferably 20 to 120 minutes, more preferably 30 to 60 minutes. The heat treatment is preferably carried out in an inert gas atmosphere such as helium gas, argon gas, or nitrogen gas.

[0042] The application of the diamond electrode-forming composition and the heat treatment may be repeated multiple times until an electrode layer having a desired thickness is obtained. The thickness of the electrode layer is preferably 50 to 10,000 μm, and more preferably 100 to 1,000 μm.

[0043] After the electrode layer is formed, if necessary, a pressure treatment may be carried out using a flat press, a calender roll, etc. Such a pressure treatment tends to reduce the electrical resistance of the electrode layer.

[0044] [Base layer] The diamond electrode according to this embodiment may have an underlayer between the substrate and the electrode layer, which comprises at least one selected from the group consisting of platinum, metal oxides, and semi-metal oxides.By having the underlayer on the diamond electrode, oxidation of the substrate is suppressed, and the durability (withstand current density) of the diamond electrode tends to be improved.It is preferable that the underlayer is formed on the entire surface of the substrate.

[0045] Examples of metal oxides and metalloid oxides contained in the underlayer include oxides of Group 4 elements (Ti, Zr, Hf) of the periodic table, oxides of Group 5 elements (V, Nb, Ta), oxides of Group 6 elements (Mo), oxides of Group 7 elements (Mn), oxides of Group 13 elements (Al), oxides of Group 14 elements (Si, Ge, Sn, Pb), and oxides of Group 15 elements (As, Sb, Bi). Among these, oxides of Group 4 elements, Group 5 elements, Group 13 elements, and Group 14 elements are preferred from the viewpoint of electrical conductivity.

[0046] The underlayer can be formed by applying a composition for forming an underlayer, which contains at least one compound selected from the group consisting of a platinum compound, a metal oxide precursor, and a semi-metal oxide precursor, and a solvent, to a substrate, and then baking the composition. The composition for forming an underlayer may further contain other components such as an acid and a surfactant.

[0047] The platinum compound is not particularly limited as long as it can produce platinum after calcination, and examples thereof include platinum chloride, platinum complexes, etc. The metal oxide precursor and the semi-metal oxide precursor are not particularly limited as long as it can produce a metal oxide or semi-metal oxide after calcination, and examples thereof include metal or semi-metal chlorides, etc.

[0048] The total content of the platinum compound, metal oxide precursor, and semi-metal oxide precursor in the undercoat layer-forming composition is preferably 0.01 to 1 mol / L, and more preferably 0.1 to 0.7 mol / L.

[0049] Examples of the solvent include alcoholic solvents such as methanol, ethanol, 1-propanol, 2-propanol, 2-butanol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, polyethylene glycol, glycerin, 1,4-butanediol, 1,6-hexanediol, cyclohexanediol, sorbitol, and xylitol; water; and the like.

[0050] The method for applying the undercoat layer-forming composition is not particularly limited and may be appropriately selected depending on the shape of the substrate. Examples of the application method include dip coating and spray coating.

[0051] After the base layer-forming composition is applied, the substrate is dried and fired. The firing temperature is preferably 400 to 800° C. The firing time is preferably 1 to 10 hours.

[0052] The application and baking of the undercoat layer-forming composition may be repeated multiple times until an undercoat layer having a desired thickness is obtained. The thickness of the undercoat layer is preferably 0.01 to 10 μm, and more preferably 0.1 to 1 μm.

[0053] [Uses of diamond electrodes] The diamond electrode according to this embodiment can be used for various purposes without any particular limitation. For example, the diamond electrode according to this embodiment can be suitably used in electrolytic processing equipment, electrochemical sensors, etc.

[0054] <Electrolytic treatment equipment and ozone generation equipment> The electrolytic treatment device according to this embodiment includes an electrolytic cell, an anode which is the diamond electrode according to this embodiment, and a cathode. The electrolytic treatment device according to this embodiment can be, for example, an ozone generator that generates ozone (ozone water) by electrolysis of water. The ozone generator is preferably a so-called zero-gap cell in which the anode and the cathode are closely attached to a solid polymer electrolyte membrane.

[0055] FIG. 1 shows an example of the schematic configuration of an ozone generator equipped with a diamond electrode according to this embodiment. The ozone generator 100 shown in FIG. 1 includes an anode 110, a cathode 120, a solid polymer electrolyte membrane 130, and an electrolytic cell 140. The anode 110 is in close contact with one surface of the solid polymer electrolyte membrane 130, and the cathode 120 is in close contact with the other surface of the solid polymer electrolyte membrane 130. The electrolytic cell 140 is separated by the solid polymer electrolyte membrane 130 into an anode chamber 140a and a cathode chamber 140b. The anode chamber 140a has a supply port 141a and an outlet 142a. The cathode chamber 140b has a supply port 141b and an outlet 142b.

[0056] The anode 110 may be, for example, a diamond electrode according to this embodiment, in which an electrode layer is formed on the main surface of a planar metal substrate having a plurality of through-holes and on the inner surfaces of the through-holes. The cathode 120 may be, for example, a porous planar metal substrate or a planar metal substrate having a plurality of through-holes. The solid polymer electrolyte membrane 130 may be, for example, a perfluorosulfonic acid cation exchange membrane.

[0057] In the ozone generator 100, when pure water is supplied from the supply ports 141a and 141b while a DC voltage is applied between the anode 110 and the cathode 120, ozone water is discharged from the outlet 142a of the anode chamber 140a, and hydrogen water is discharged from the outlet 142b of the cathode chamber 140b. [Example]

[0058] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0059] <Experimental Example 1: Production of conductive diamond particles (BDDP)> Diamond particles with a particle diameter of 40 to 60 μm were used as the particulate substrate. First, impurities contained in the diamond particles (Co, Fe, various sp 2 To remove impurities (e.g., carbon), the diamond particles were cleaned according to a previously reported method. Specifically, the diamond particles were immersed in aqua regia (a 3:1 volume mixture of hydrochloric acid and nitric acid) and heated at 60°C for 30 minutes, followed by immersion in 30% hydrogen peroxide and heating at 60°C for 30 minutes. The particles were then washed sequentially with ultrapure water, 2-propanol, and acetone, and dried in a heating furnace. Approximately 0.8 g of the cleaned diamond particles were then weighed and subjected to microwave plasma CVD to form a BDD layer on the diamond particle surface, yielding conductive diamond particles (BDDP). The deposition conditions were microwave power: 1300 W, stage temperature: 800°C, chamber pressure: 50 Torr, deposition time: 8 hours, and boron concentration: 20,000 ppm.

[0060] <Experimental Example 2: Manufacturing of diamond electrodes> Example 1 The conductive diamond particles (10 mg) produced in Experimental Example 1 and polyvinylidene fluoride (mass average molecular weight: 2.8 × 10 5 ) (40 mg) and N-methyl-2-pyrrolidone (350 mL) were mixed to prepare a composition for forming a diamond electrode.

[0061] One-fourth of the obtained diamond electrode-forming composition was applied to a titanium mesh substrate (2.5 cm × 2.5 cm) so as not to block the holes, and fired in a muffle furnace at 100 ° C. for 30 minutes and then at 200 ° C. for 30 minutes. This was repeated three times until the entire amount of the composition was applied to the substrate and fired, and the diamond electrode of Example 1 was obtained.

[0062] (Comparative Example 1) The conductive diamond particles (10 mg) produced in Experimental Example 1 and polyvinylidene fluoride (mass average molecular weight: 2.8 × 10 5 ) (5 mg) and N-methyl-2-pyrrolidone (350 mL) were mixed to prepare a composition for forming a diamond electrode.

[0063] One-fourth of the obtained diamond electrode-forming composition was applied to a titanium mesh substrate (2.5 cm × 2.5 cm) so as not to block the holes, and fired in a muffle furnace at 100 ° C for 30 minutes and then at 200 ° C for 30 minutes. This was repeated three times until the entire amount of the composition was applied to the substrate and fired, and a diamond electrode of Comparative Example 1 was obtained.

[0064] <Experimental Example 3: Cyclic voltammetry (CV) measurement using an electrolytic cell equipped with diamond electrodes> The diamond electrode of Example 1 was used as the anode, and a titanium mesh substrate (2.5 cm x 2.5 cm) was used as the cathode. A solid polymer electrolyte membrane (Nafion N-117, manufactured by DuPont) was sandwiched between the anode and the cathode. The resulting structure was placed inside an electrolytic cell (30 mm x 30 mm x 4 mm) with a supply port and a discharge port formed therein, to prepare an electrolytic cell. The electrochemical measurement device (HZ-7000, manufactured by Meiden Hokuto Co., Ltd.) was used to measure cyclic voltammetry (CV) in ultrapure water for the prepared electrolytic cell. The measurement voltage was 0 to 2.5 V, and the scanning speed was 100 mV / sec.

[0065] The cyclic voltammogram obtained by CV measurement is shown in Figure 2. The results in Figure 2 show that the diamond electrode of Example 1 has a wide potential window.

[0066] <Experimental Example 4: Ozone generation using an electrolytic cell equipped with diamond electrodes> Using the diamond electrode of Example 1 or Comparative Example 1 as the anode, an electrolytic cell was fabricated in the same manner as in Experimental Example 3. Then, using the fabricated electrolytic cell, constant voltage electrolysis of ultrapure water was carried out under conditions of 10 V for 30 minutes.

[0067] Figure 3 shows the change in current value over time during constant-voltage electrolysis. As shown in Figure 3, the electrolytic cell using the diamond electrode of Example 1 exhibited a stable current value during electrolysis, but the electrolytic cell using the diamond electrode of Comparative Example 1 showed a significant drop in current value during electrolysis. When the ozone generated by 30 minutes of constant-voltage electrolysis was quantified by iodometric titration, the amount of ozone generated in the electrolytic cell using the diamond electrode of Example 1 was 2.16 mg / L, with a current efficiency of 0.80%, and the amount of ozone generated in the electrolytic cell using the diamond electrode of Comparative Example 1 was 0.65 mg / L, with a current efficiency of 0.36%. After electrolysis, visual observation of the surface of the diamond electrode of Comparative Example 1 revealed that the conductive diamond layer had partially peeled off. [Explanation of symbols]

[0068] 100 Ozone generating device, 110 Anode, 120 Cathode, 130 Solid polymer electrolyte membrane, 140 Electrolytic cell, 140a Anode chamber, 140b Cathode chamber, 141a, 141b Supply port, 142a, 142b Removal port

Claims

1. The conductive diamond particles, the binder resin, and the solvent are contained, A diamond electrode-forming composition in which the content of the binder resin is 1 to 10 parts by mass per 1 part by mass of the content of the conductive diamond particles.

2. The diamond electrode-forming composition according to claim 1 , further comprising a conductive additive.

3. The diamond electrode forming composition according to claim 1 , wherein the binder resin contains polyvinylidene fluoride.

4. A method for manufacturing a diamond electrode, comprising the steps of applying the diamond electrode-forming composition according to any one of claims 1 to 3 to a substrate and performing a heat treatment to form an electrode layer on the surface of the substrate.

5. the substrate is a planar substrate having a plurality of through holes, The method for producing a diamond electrode according to claim 4, wherein the diamond electrode-forming composition is applied to the main surface of the planar substrate and the inner surface of the through-hole.

6. 6. The method for producing a diamond electrode according to claim 5, wherein the substrate is a metal mesh, an expanded metal, a rolled lath, or a punched metal.

7. a planar substrate having a plurality of through holes; and an electrode layer containing conductive diamond particles and a binder resin, the electrode layer being formed on a main surface of the planar substrate and on the inner surfaces of the through holes; A diamond electrode, wherein the content of the binder resin in the electrode layer is 1 to 10 parts by mass per 1 part by mass of the conductive diamond particles.

8. The diamond electrode according to claim 7, wherein the binder resin comprises polyvinylidene fluoride.

9. An electrolytic treatment device comprising an electrolytic cell, an anode which is the diamond electrode according to claim 7 or 8, and a cathode.

10. An ozone generating device comprising an electrolytic cell, an anode which is the diamond electrode according to claim 7 or 8, and a cathode.

11. a solid polymer electrolyte membrane separating the anode and the cathode; The ozone generator according to claim 10 , wherein the anode is in close contact with one surface of the solid polymer electrolyte membrane, and the cathode is in close contact with the other surface of the solid polymer electrolyte membrane.

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