JP2008248378A - Electrode for electrolysis and electrolysis unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for electrolysis capable of efficiently forming ozone by electrolysis of an electrolytic solution (e.g., water) at ordinary temperature with a low current density and an electrolysis unit using the electrode. <P>SOLUTION: The electrode 1 for electrolysis includes a substrate 2 and a surface layer 5 formed on the surface of the substrate 2, and the surface layer 5 is made of an amorphous insulator, for example, a thin film of amorphous tantalum oxide, amorphous tungsten oxide or amorphous aluminum oxide. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrode for electrolysis used in an industrial or consumer electrolysis process.

  In general, ozone is a substance having a very strong oxidizing power, and water in which the ozone is dissolved, so-called ozone water is widely used for cleaning and sterilization such as water and sewage, food, etc., and cleaning treatment in semiconductor device manufacturing processes. Expected to be used in processing. As a method of generating ozone water, a method of dissolving ozone generated by ultraviolet irradiation or discharge in water, a method of generating ozone in water by electrolysis of water, and the like are known.

  Patent Document 1 discloses an ozone water generating device that includes ozone generating means for generating ozone gas by an ultraviolet lamp and a tank for storing water, and generates ozone water by supplying the generated ozone gas to water in the tank. Has been. Patent Document 2 discloses an ozone water generator that mixes ozone gas and water generated by a discharge-type ozone gas generator at a predetermined ratio with a mixing pump in order to efficiently dissolve ozone gas in water. Yes.

  However, in the ozone water generation method in which ozone gas is generated by the ultraviolet lamp or discharge method as described above and this ozone gas is dissolved in water, an operation for dissolving the ozone gas in the water is required because of the ozone gas generation device and the operation for dissolving the ozone gas in water. There is a problem that it is easy to make complicated, and it is difficult to generate ozone water having a desired concentration with high efficiency because the generated ozone gas is dissolved in water.

  Patent Document 3 discloses a method for generating ozone in water by electrolysis of water as a method for solving the above problems. In such a method, an electrode for generating ozone, which is configured to include an electrode substrate formed of a porous body or a net-like body and an electrode catalyst containing an oxide of a platinum group element or the like, is used.

Patent Document 4 discloses that ozone is generated by electrolytic treatment of simulated tap water as an electrolyte solution with an electrode for electrolysis having a surface layer made of a dielectric such as tantalum oxide.
Japanese Patent Laid-Open No. 11-77060 JP-A-11-333475 JP 2002-80986 A JP 2007-016303 A

  However, in the method shown in Patent Document 3 as described above, since diamond is used as the electrode material, there is a problem that the cost of the device itself increases.

In addition, in the method of generating ozone water by electrolysis of water shown in Patent Document 3, platinum group elements are standard anode materials, and are characterized by being hardly dissolved in an aqueous solution containing no organic matter. As an ozone generation electrode, ozone generation efficiency is low, and it is difficult to generate ozone water by a highly efficient electrolysis method. In addition, in the conventional ozone water generation by electrolysis using an electrode for generating ozone, electrolysis for generating ozone requires a high current density of 1 A / cm ² or more, and the electrolyte is used at a low temperature. There is a problem that a great deal of energy is consumed. Furthermore, platinum is expensive, and there is another problem that it is toxic when lead dioxide is used.

  Furthermore, even when the electrode for electrolysis disclosed in Patent Document 4 as described above is used, ozone is generated, but further improvement in ozone generation current efficiency has been desired.

  Accordingly, the present invention has been made to solve the conventional technical problems, and provides an electrode for electrolysis that can generate ozone with high efficiency by electrolysis of water with a low current density. To do.

  The electrode for electrolysis of the present invention comprises a substrate and a surface layer formed on the surface of the substrate, and the surface layer is an amorphous insulator.

  The electrode for electrolysis according to the invention of claim 2 is characterized in that, in the above invention, the insulator is a single metal oxide or a composite metal oxide.

  The electrode for electrolysis according to a third aspect of the present invention is characterized in that, in each of the above inventions, the insulator is tantalum oxide or tungsten oxide.

  According to a fourth aspect of the present invention, there is provided an electrode for electrolysis according to the first or second aspect of the present invention, wherein the insulator is aluminum oxide.

  The electrode for electrolysis according to the invention of claim 5 is characterized in that, in each of the above inventions, the surface layer has a thickness of 20 nm or more and 2000 nm or less.

  According to a sixth aspect of the present invention, the electrode for electrolysis according to any one of the first to fifth aspects of the present invention is such that the substrate is located inside the surface layer, and an intermediate layer is formed of a hardly oxidizable metal on the surface of the substrate. It is characterized by being.

  An electrolysis unit according to a seventh aspect of the invention is configured such that an anode having water permeability is constituted by the electrode for electrolysis according to any of the first to sixth aspects, and the cathode having water permeability with the anode is a cation exchange membrane. It is arrange | positioned on both surfaces of this.

  According to the present invention, in the electrode for electrolysis comprising a substrate and a surface layer formed on the surface of the substrate, since the surface layer is an amorphous insulator, the low current density using the electrode as an anode Ozone can be efficiently generated by electrolysis of the electrolyte solution.

  In particular, since the temperature of the electrolyte solution is not particularly low as in the prior art and a high current density is not required, it is possible to reduce the power consumption required for ozone generation.

  According to the invention of claim 2, in the above invention, the insulator is a single metal oxide or a composite metal oxide, in particular, tantalum oxide or tungsten oxide as in the invention of claim 3, whereby the Fermi level is obtained. The empty level near the bottom of the conductor, which is at an energy level about half the band gap higher, receives electrons from the electrolyte. Oxygen generation reaction is suppressed as compared with the case of being composed of things, etc., and ozone generation reaction occurs more efficiently instead.

  For this reason, the generation of electrons at a higher energy level can cause the ozone generation reaction to increase the efficiency of ozone generation.

  According to the invention of claim 4, in each of the above inventions, since the insulator is aluminum oxide, the electrode for electrolysis of each of the above inventions can be constituted by a relatively inexpensive material, and the production cost is low. Can be achieved. In addition, since no toxic substances such as lead dioxide are used, the environmental burden can be reduced.

  According to the invention of claim 5, in each of the above-mentioned inventions, the surface layer has a thickness of 20 nm or more and 2000 nm or less, so it can be constituted by a thin film, via an impurity level in the surface layer, or The Fowler-Nordheim tunnel allows electrons to move inside the electrode. Therefore, in the electrode reaction at the anode, the empty level near the bottom of the conductor, which is at an energy level about half the band gap higher than the Fermi level, can receive electrons from the electrolyte, and the electrons move at a higher energy level. Occurrence of this makes it possible to perform electrolysis at a low current density and efficiently generate ozone.

  According to the invention of claim 6, in each of the above-mentioned inventions, the substrate is located on the inner side of the surface layer, and the intermediate layer is formed of a hardly oxidizable metal on the surface of the substrate. As described above, the electrons can effectively move in the surface layer. Therefore, an electrode reaction can occur at a high energy level on the surface of the surface layer. Thereby, ozone can be generated efficiently at a lower current density.

  In particular, according to the invention, since the intermediate layer is formed of a hardly oxidizable metal on the surface of the substrate, the problem that the surface of the substrate is oxidized and made non-conductive when electrolysis is performed using the electrode is avoided. can do. Thereby, durability of an electrode can be improved. In addition, it is possible to reduce the production cost as compared with the case where the entire substrate is made of the material constituting the intermediate layer, and in this case, ozone can be generated efficiently in the same manner. .

  An electrolysis unit according to a seventh aspect of the invention is configured such that an anode having water permeability is constituted by the electrode for electrolysis according to any of the first to sixth aspects, and the cathode having water permeability with the anode is a cation exchange membrane. Therefore, even if the electrolyte solution is pure water, ozone can be efficiently generated by moving protons through the cation exchange membrane.

  Hereinafter, preferred embodiments of the electrode for electrolysis of the present invention will be described with reference to the drawings. FIG. 1 is a plan sectional view of an electrode 1 for electrolysis according to the present invention. As shown in FIG. 1, the electrode for electrolysis 1 includes a substrate 2, an adhesion layer 3 formed on the surface of the substrate 2, an intermediate layer 4 formed on the surface of the adhesion layer 3, and the intermediate layer 4. And a surface layer 5 formed on the surface. Moreover, the electrode 1 for electrolysis is provided with a titanium plate 6 as an electric conduction part on a base 2, and the titanium plate 6 and the intermediate layer 4 are silver paste as a conductive material provided on the end face of the electrode 1. 7 enables conduction. Further, the silver paste 7 and the titanium plate 6 are covered with the sealing material 8 and do not contribute to electrolysis. In addition, the method of taking conduction is not limited to this.

  In the present invention, the substrate 2 is a conductive material such as platinum (Pt), valve metal such as titanium (Ti), tantalum (Ta), zirconium (Zr), niobium (Nb), or two or more of these valve metals. Or an alloy of silicon (Si) or the like. In particular, the substrate 2 used in this embodiment uses silicon whose surface is processed flat.

  The adhesion layer 3 is formed on the surface of the substrate 2 and is used for improving the adhesion between the substrate 2 and the intermediate layer 4 formed of platinum on the surface of the adhesion layer 3. It is made of titanium nitride or the like. In this embodiment, titanium oxide is used.

  The intermediate layer 4 is a metal that is difficult to oxidize, such as platinum, gold (Au), or a conductive metal oxide, such as iridium oxide, palladium oxide, ruthenium oxide, oxide superconductor, or the like. The metal having conductivity even when oxidized is composed of ruthenium (Ru), rhodium (Rh), palladium (Pd), iridium (Ir), or silver (Ag) contained in the platinum group element. In addition, about a metal oxide, it is not limited to the thing in which the intermediate | middle layer 4 was comprised previously as an oxide, The thing oxidized by electrolysis and including a metal oxide shall also be included.

  However, when the intermediate layer 4 is composed of a conductive metal oxide, such as iridium oxide, the oxygen atoms constituting the metal oxide adversely affect the conductor. It is desirable to use a hardly oxidizable metal. In this embodiment, the intermediate layer 4 is made of platinum.

  When the base 2 is made of platinum, the surface of the base 2 is naturally made of platinum, so that the intermediate layer 4 need not be specially formed. However, when the base 2 is made of platinum, the cost increases. Therefore, industrially, the base 2 is made of an inexpensive material, and the surface of the base 2 is made of a noble metal or the like. It is preferable to form the intermediate layer 4 to be formed. Further, the base 2 is made of a non-conductive substance, for example, a glass plate, and the base 2 has at least a contact surface with a surface layer 5 described later coated with a conductive material. For example, it is not limited to the said structure. This also makes it possible to suppress an increase in cost required for the material used for the structure of the base 2.

  The surface layer 5 is an amorphous (indeterminate, amorphous) insulator together with the intermediate layer 4 so as to cover the intermediate layer 4. In this embodiment, the insulator is formed in layers on the surface of the substrate 2 with tantalum oxide (TaOx), tungsten oxide (WOx), or aluminum oxide (AlOx). The surface layer 5 is formed in a thin film having a predetermined thickness, which is larger than 0 and not larger than 1 mm, preferably 20 nm to 2000 nm in this embodiment.

  In this embodiment, amorphous tantalum oxide, tungsten oxide, and aluminum oxide are cited as the insulator. However, the present invention is not limited to this, and an amorphous single metal oxide that is an insulator, Specifically, TiOx, NbOx, HfOx, NaOx, MgOx, KOx, CaOx, ScOx, VOx, CrOx, MnOx, FeOx, CoOx, NiOx, CuOx, ZnOx, GaOx, RbOx, SrOx, YOx, ZrOx, MoOx, MoOx, MoOx, , SnOx, SbOx, CsOx, BaOx, LaOx, CeOx, PrOx, NdOx, PmOx, SmOx, EuOx, GdOx, TbOx, DyOx, HoOx, ErOx, TmOx, YbOx, LuOB, Lub amorphous Composite metal oxides, or, SiOx, or the like may be used GeOx.

  Next, with reference to the flowchart of FIG. 2, the manufacturing method of the electrode 1 for electrolysis of Example 1 of this invention is demonstrated. First, as a step S1, pretreatment of silicon constituting the substrate 2 is performed. Here, it is desirable that the silicon has an increased conductivity by introducing phosphorus (P), boron (B), or the like as impurities. The silicon used has a very flat surface. In this embodiment, silicon is used as the substrate 2, but other conductive materials as described above may be used.

  In the pretreatment, the silicon substrate 2 is treated with 5% hydrofluoric acid, and the natural oxide film formed on the surface of the substrate 2 is removed. Thereby, the surface of the base 2 is made flatter. Note that the preprocessing may not be performed. Thereafter, the surface of the substrate 2 is rinsed with pure water, and thereafter introduced into the chamber of an existing sputtering apparatus in step S2 to form a film.

In step S <b> 2, the adhesion layer 3 for improving the adhesion of the intermediate layer 4 as described above is formed on the surface of the substrate 2. The formation of the adhesion layer 3 on the substrate 2 is performed by a reactive sputtering method. Since the adhesion layer 3 is composed of titanium oxide, Ti is used as the first target, the input power is 6.17 W / cm ² , the oxygen partial pressure is 52% (Ar: O ₂ 24:26), and the film formation pressure is set to 0. At 6 Pa, film formation is performed at room temperature for 10 minutes. As a result, an adhesion layer 3 made of titanium oxide having a thickness of about 50 nm is formed on the surface of the substrate 2. In this embodiment, the reactive sputtering method is used as the method for forming the adhesion layer 3, but the method is not limited to this. For example, the sputtering method, the CVD method, the ion plating method, the plating method, Alternatively, a combination of these methods and thermal oxidation may be used.

Next, in step S3, the intermediate layer 4 is formed on the surface of the substrate 2 on which the adhesion layer 3 is formed. The formation of the intermediate layer 4 on the substrate 2 is performed by a sputtering method. In this embodiment, since the intermediate layer 4 is made of platinum, Pt (80 mmφ) is used as the first target, the input power is 4.63 W / cm ² , the Ar gas pressure is 0.7 Pa, and about 1 minute at room temperature. Film formation is performed for 11 seconds. As a result, an intermediate layer 4 having a thickness of about 200 nm is formed on the surface of the substrate 2 on which the adhesion layer 3 is formed. In the present embodiment, the sputtering method is used as the film formation method of the intermediate layer 4, but is not limited to this, and examples thereof include a CVD method, a vapor deposition method, an ion plating method, and a plating method. It may be acceptable.

  Next, the surface layer 5 is formed on the surface of the substrate 2 on which the intermediate layer 4 is formed. In this embodiment, since the surface layer 5 is formed using a spin coating method, an organoaluminum compound solution as a surface layer constituent material is applied to the surface of the substrate 2 on which the intermediate layer 4 is formed. In this embodiment, since the surface layer 5 is composed of aluminum oxide, a functional group such as a hydroxyl group, an aldehyde group, an alkyl group, a carboxyl group, or an alkoxyl group is coordinated to aluminum having a coordination number of 3 as an organoaluminum compound. Is used. In addition, the weight percent of aluminum in the organoaluminum compound solution is preferably about 0.4% to 3% of the whole. In this example, an organoaluminum compound solution is used as the surface layer constituent material, but the present invention is not limited thereto, and is a compound containing aluminum that can remove substances other than aluminum by firing, For example, aluminum chloride, aluminum bromide, aluminum iodide, or the like may be used.

  In step S4, a surface layer constituting material is dropped on the surface of the substrate 2 on which the intermediate layer 4 is formed, and a thin film is formed by spin coating. The conditions for the spin coating method in this example are 1000 rpm for 5 seconds and 3000 rpm for 15 seconds. Thereafter, drying is performed for 10 minutes each at room temperature and 200 ° C. (step S5). Thereby, the surface layer 5 is formed on the surface of the intermediate layer 4 of the substrate 2 by the surface layer constituent material containing the aluminum compound.

  Thereafter, the substrate 2 on which the intermediate layer 4 and the surface layer 5 are formed is fired (annealed) in step S6 in a muffle furnace at 400 ° C. to 900 ° C., in this embodiment, 600 ° C. in an air atmosphere for 10 minutes. Is performed, and the electrode 1 for electrolysis is obtained. Thereby, the surface layer constituent material applied to the surface of the intermediate layer 4 is uniformly made of aluminum oxide. In this example, the surface layer 5 of aluminum oxide formed by firing is subjected to the main film forming operation once, so that the thickness is about 25 nm. Note that the thickness of the surface layer 10 may be about 20 nm to 2000 nm by repeating the film forming operation a plurality of times.

  The surface layer 5 of the electrode 1 for electrolysis obtained as described above is all made of aluminum oxide. That is, the surface layer constituting material includes a compound containing aluminum, for example, as described above, an organic aluminum compound in which a plurality of functional groups are coordinated in addition to aluminum, aluminum chloride, aluminum bromide, aluminum iodide, or the like. However, by firing, substances other than aluminum, that is, functional groups composed of organic substances, chlorine, bromine and the like are removed. On the other hand, aluminum reacts with oxygen in the atmosphere to become aluminum oxide.

  FIG. 3 shows an X-ray diffraction pattern of the surface layer 5 of the electrode 1 for electrolysis obtained as described above. In FIG. 3, the electrode 1 for electrolysis was configured under the conditions that the firing temperature for forming the surface layer 5 was 700 ° C., 750 ° C., 800 ° C., 850 ° C., and 900 ° C. In general, X-ray diffraction (XRD) is used for the analysis of the crystal structure, whereby the crystal structure of aluminum oxide constituting the surface layer 5 can be analyzed. In this example, observation was performed using an X-ray diffractometer (D8 Discover manufactured by Bruker AXS).

According to this, each diffraction peak (2θ) shown in the X-ray diffraction pattern of the surface layer 5 of the electrode 1 for electrolysis obtained in this example is the electrode 1 constituted by any firing temperature. They were about 36.1 °, about 38 °, and about 39.6 °. In general, hexagonal systems such as α-alumina and β-alumina are known as the crystal structure of aluminum oxide, but the diffraction peak (2θ) peculiar to the aluminum oxide (Al ₂ O ₃ ) is 35.15 °, 57.50 ° and 43.36 ° do not exist in the X-ray diffraction pattern of the surface layer 5 of any electrode 1 for electrolysis. Therefore, it can be seen that the aluminum oxide forming the surface layer 5 of the electrode 1 for electrolysis by the method as described above is in an amorphous form having no crystal structure, so-called amorphous form. In this case, the diffraction peak near 36.1 ° is a peak of titanium oxide (101) constituting the adhesion layer 3, and the diffraction peak near 39.6 ° is platinum (111) constituting the intermediate layer 4. ) Peak.

  In this embodiment, the surface layer 5 is made of an amorphous material by applying a surface layer constituent material containing an aluminum compound to the substrate surface (in this embodiment, the surface of the intermediate layer 4) by spin coating and firing at a predetermined temperature. Although it is formed of type aluminum oxide, the method of forming the surface layer 5 with the amorphous type aluminum oxide is not limited to this.

  As another method, there is a method of forming the surface layer 5 by a thermal CVD method. In this thermal CVD method, the adhesion layer 3 and the intermediate layer 4 are sequentially formed on the surface of the substrate 2 in the same manner as in the above embodiment, and then the organoaluminum compound as the surface layer constituent material is vaporized and an appropriate carrier gas is used. Then, the chemical reaction is conducted on the surface of the substrate 2 heated to a high temperature, for example, 500 ° C. to 900 ° C., preferably 600 ° C. to 800 ° C.

  Thereby, a substance excluding aluminum of the organoaluminum compound which is a surface layer constituent material, for example, an organic substance is removed on the surface of the substrate 2 heated to a high temperature, and only the aluminum reacts with oxygen in the atmosphere to form the substrate as aluminum oxide 2 formed on the surface. The aluminum oxide formed on the surface of the substrate 2 (actually the surface of the intermediate layer 4) constitutes an amorphous thin film (aluminum oxide film).

  In addition, as a method of forming the surface layer 5 with amorphous aluminum oxide, for example, there is a dip method.

In this embodiment, since the adhesion layer 3 composed of titanium oxide is formed on the surface of the substrate 2 composed of silicon, the platinum constituting the intermediate layer 4 directly becomes the substrate 2. By diffusing to the inside, platinum silicide is formed, and it is possible to prevent oxidation and electroconductivity during electrolysis. Further, the adhesion of the platinum constituting the intermediate layer 4 to the substrate 2 can be improved by the adhesion layer 3 composed of titanium oxide. Thereby, durability of the electrode 1 can be improved.
(Electrolysis method using each electrode for electrolysis and its evaluation)
Next, generation of ozone by electrolysis using the electrode 1 for electrolysis manufactured as described above will be described with reference to FIGS. FIG. 4 is a schematic explanatory view of the electrolysis apparatus 10 to which the electrode 1 for electrolysis is applied, and FIG. 5 is a diagram showing the efficiency of ozone generation current when using the electrode for electrolysis prepared according to each condition.

  The electrolysis apparatus 10 includes a treatment tank 11, an electrode 1 for electrolysis as an anode as described above, an electrode 12 as a cathode, and a power source 15 that applies a direct current to the electrodes 1 and 12. Then, a cation exchange membrane (diaphragm: Nafion manufactured by DuPont, which is located between the electrodes 1 and 12 and partitioned into one region where the electrode 1 exists in the treatment tank 11 and the other region where the electrode 12 exists) Name)) 14 is provided. Further, a stirring device 16 is provided in a region where the electrode 1 for electrolysis as an anode is immersed.

In the treatment tank 11, simulated tap water 13 as an electrolyte solution is stored. In the experiment in this example, simulated tap water is used as the electrolyte solution. However, by providing a cation exchange membrane, substantially the same effect can be obtained even when pure water is treated. The electrolyte solution used in the experiment is an aqueous solution that simulates tap water. The component composition of the simulated tap water 23 is 5.75 ppm for Na ⁺ , 10.02 ppm for Ca ²⁺ , and 6 for Mg ^2+. 0.08 ppm, K ⁺ is 0.98 ppm, Cl ⁻ is 17.75 ppm, SO ₄ ²⁻ is 24.5 ppm, and CO ₃ ²⁻ is 16.5 ppm.

  The electrode 1 for electrolysis is produced by the manufacturing method as described above, and the thickness of the surface layer 5 of the electrode 1 for electrolysis is about 25 nm, and the firing temperature when forming the surface layer 5 is: 600 ° C. For comparison, an electrode for electrolysis (AlOx sputtering) formed by sputtering rather than spin coating the aluminum oxide constituting the surface layer 5, and tantalum oxide (TaOx) as the material constituting the surface layer 5 are spun. An electrode for electrolysis (TaOx spin coating) formed by a coating method and an electrode for electrolysis (TiOx spin coating) formed by spin coating of titanium oxide (TiOx) as a material constituting the surface layer 5 are used.

  In the AlOx sputtering electrolysis electrode, the surface layer 5 is formed on the surface of the intermediate layer 4 formed by the same method as in the present embodiment. Therefore, the target is Al as the surface layer constituent material, and the rf power is 100 W. Film formation is performed at room temperature with an Ar gas pressure of 0.9 Pa and a distance between the substrate 2 and the target of 60 mm. Thereafter, the substrate 2 on which the surface layer 5 is formed is obtained by performing thermal oxidation at 600 ° C. in an air atmosphere for 30 minutes in a muffle furnace.

  In the electrode for electrolysis of the TaOx spin coat, the surface layer 5 made of tantalum oxide is formed on the surface of the intermediate layer 4 formed by the same method as in the present embodiment by the spin coat method under the same conditions. Is done. And it was obtained by baking for 10 minutes in 600 degreeC and the atmospheric condition of baking temperature. The surface layer 5 has a thickness of about 25 nm.

  In the electrode for electrolysis of the TiOx spin coat, a surface layer 5 made of titanium oxide is formed on the surface of the intermediate layer 4 by a spin coat method under the same conditions. And it was obtained by baking for 10 minutes in 600 degreeC and the atmospheric condition of baking temperature. In addition, the thickness of the surface layer 5 is about 50 nm. In addition, the surface layer 5 produced | generated by the said conditions is formed with the titanium oxide which takes anatase type crystal structure.

  In addition, the film thickness of the surface layer of each of the electrodes for electrolysis described above is based on the obtained amounts of Al, Ta, and Ti obtained by evaluation with a fluorescent X-ray analyzer (JSX-3220ZS Element Analyzer manufactured by JEOL Ltd.). It is obtained by converting the thickness.

  On the other hand, platinum is used for the electrode 12 as a cathode. In addition to this, an insoluble electrode obtained by baking platinum on the surface of a titanium substrate, a platinum-iridium-based electrode for electrolysis, a carbon electrode, or the like may be used.

With the above configuration, 150 ml of simulated tap water 13 is stored in each region in the treatment tank 11, and the electrode 1 for electrolysis and the electrode 12 are immersed in the simulated tap water, respectively. The distance between each electrode is 10 mm. Then, a constant current having a current density of about 25 mA / cm ² is applied to the electrolysis electrode 1 and the electrode 12 by the power source 15. Moreover, the temperature of the simulated tap water 13 shall be +15 degreeC.

  In this example, the amount of ozone generated by each electrolysis electrode is determined by measuring the amount of ozone generated in simulated tap water 13 after electrolysis for 5 minutes under the above conditions by the indigo method (DR4000 manufactured by HACH). Evaluation is performed by calculating the ratio of the electric charge contributing to the ozone generation relative to the electric charge amount, that is, the ozone generation current efficiency.

  As shown in FIG. 5, in this experiment, when the electrode 1 for electrolysis prepared as in this example (the surface layer 5 is made of AlOx by spin coating) is used, the ozone generation current The efficiency was about 5.64%. On the other hand, the ozone generation current efficiency in the case where the surface layer 5 is made of AlOx by the sputtering method is about 4.0%. Thus, it can be seen that the ozone generation efficiency is higher when the surface layer 5 is formed by the spin coating method than when the surface layer 5 is formed by the sputtering method.

  Further, when the surface layer 5 is composed of another material by spin coating, for example, when it is composed of TaOx (the surface layer of the electrode for electrolysis in the experiment is composed of crystallized tantalum oxide), ozone generation The current efficiency is about 1.5%, and when it is composed of TiOx (the surface layer of the electrode for electrolysis in the experiment is composed of titanium oxide having an anatase type crystal structure), the ozone generation current efficiency is About 0.3%. Even when the surface layer 5 is formed by the same method and having substantially the same film thickness, TaOx (crystallized tantalum oxide in the experiment) or TiOx (crystallized titanium oxide in the experiment) In contrast, when the surface layer 5 is formed of AlOx, the ozone generation efficiency is remarkably high.

  From the above experimental results, it is possible to generate ozone in the electrolyte solution by electrolyzing the electrolyte solution using each electrolysis electrode as an anode. However, the AlOx formed by the spin coating method of this embodiment can be used. It can be seen that when the electrode 1 for electrolysis having the surface layer 5 is used, the ozone generation efficiency is remarkably higher than when the surface layer 5 is formed by other materials or other methods. This is presumably because the surface layer 5 of a thin film made of amorphous aluminum oxide is formed on the surface of the substrate 2 (actually the intermediate layer 4) by the spin coating method under the above conditions.

  In particular, the amorphous aluminum oxide thin film is formed to a thickness of 20 nm to 2000 nm, so that electrons can be made into a conductive material through impurity levels in the surface layer 5 or by a Fowler-Nordheim tunnel. It is thought that it moves to the intermediate layer 4 configured as described above.

  Usually, when a metal electrode is used as an electrode for electrolysis, an electrode reaction at the anode preferentially causes an oxygen generation reaction when an empty level immediately above the Fermi level receives electrons from the electrolyte. In addition, when the surface layer 5 is composed of a crystallized metal oxide, the metal segregates at the grain boundary between the crystals and current flows. An empty level immediately above the level receives electrons from the electrolyte, and thus preferentially causes an oxygen generation reaction.

  On the other hand, when the electrolysis electrode 1 formed with the surface layer 5 in the present invention is used, the surface layer 5 is made of amorphous aluminum oxide, so that the energy level is about half the band gap higher than the Fermi level. When an empty level near the bottom of a certain conductor receives electrons from the electrolyte, the oxygen generation reaction of the electrons is suppressed more than the above, and instead, the ozone generation reaction occurs more efficiently.

  Therefore, when the electrode 1 for electrolysis in the present invention is used, compared with the case where an electrode for electrolysis such as platinum or an electrode for electrolysis in which a surface layer is formed of crystallized tantalum oxide or titanium oxide is used. It is considered that the efficiency of ozone generation is increased because the electron transfer occurs at a higher energy level to cause an ozone generation reaction.

As a result, a predetermined low current density of 0.1 mA / cm ^{2 to} 2000 mA / cm ² , preferably 1 mA / cm ^{2 to} 1000 mA / cm ² is applied to the electrode 1 for electrolysis, thereby achieving high efficiency. It is possible to generate ozone. Further, ozone can be generated with high efficiency even when the temperature of the electrolyte solution is not particularly low and is a normal temperature such as + 15 ° C. as in this embodiment. Therefore, it is possible to reduce the power consumption required for ozone generation.

  In addition, as described above, the surface layer 5 of the electrode 1 capable of realizing ozone generation with high efficiency can be formed by the spin coating method as described above, and thus is formed by the conventional sputtering method. Compared to the case, productivity can be improved, and an electrode for electrolysis can be manufactured at a low manufacturing cost, so that the cost of equipment can be reduced. Further, the surface layer 5 is formed by the thermal CVD method as described above, so that the stability is good and high production efficiency can be realized. Furthermore, since no toxic substances such as lead dioxide are used, the environmental burden can be reduced.

  Next, with reference to the flowchart of FIG. 6, the manufacturing method of the electrode 21 for electrolysis of Example 2 of this invention is demonstrated. FIG. 7 shows a schematic configuration diagram of the electrode 21 for electrolysis obtained by the embodiment. First, as a step S11, pretreatment of silicon constituting the substrate 22 is performed in the same manner as in the above embodiment. Since the material of the base 22 is the same as that in the above embodiment, the description thereof is omitted. Thereafter, in step S12, the film is introduced into a chamber of an existing sputtering apparatus and film formation is performed.

In step S <b> 12, the adhesion layer 23 for improving the adhesion of the intermediate layer 24 as described above is formed on the surface of the substrate 22. As in the above embodiment, the formation of the adhesion layer 23 on the substrate 22 is performed by a reactive sputtering method. Since the adhesion layer 23 is composed of titanium oxide, Ti is used as the first target, the input power is 6.17 W / cm ² , the oxygen partial pressure is 52% (Ar: O ₂ 24:26), and the film formation pressure is set to 0. At 6 Pa, film formation is performed at room temperature for 10 minutes. As a result, an adhesion layer 23 made of titanium oxide having a thickness of about 50 nm is formed on the surface of the substrate 22.

Next, in step S13, the intermediate layer 24 is formed on the surface of the substrate 22 having the adhesion layer 23 formed on the surface in the same manner as in the above embodiment. The formation of the intermediate layer 24 on the substrate 22 is performed by a sputtering method. In this embodiment, since the intermediate layer 24 is composed of platinum, Pt (80 mmφ) is used as the first target, the input power is 4.63 W / cm ² , the Ar gas pressure is 0.7 Pa, and about 1 minute at room temperature. Film formation is performed for 11 seconds. As a result, an intermediate layer 24 having a thickness of about 200 nm is formed on the surface of the substrate 22 on which the adhesion layer 23 is formed.

  Next, the surface layer 25 is formed on the surface of the substrate 22 on which the intermediate layer 24 is formed. In this embodiment, the surface layer 25 is formed by sputtering. When the surface layer is formed of tantalum oxide, the target is changed to Ta which is a surface layer constituent material, the rf power is 100 W, the Ar gas pressure is 0.9 Pa, and the distance between the substrate 22 and the target is 60 mm. As described above, film formation is performed at room temperature for 5 to 180 minutes (step S14). Thereby, a surface layer 25 having a thickness of about 7 nm to 1000 nm is formed on the surface of the intermediate layer 24 of the substrate 22. The film thicknesses of the intermediate layer 24 and the surface layer 25 are obtained by obtaining the amounts of Pt and Ta supported by evaluation with fluorescent X-rays and converting the thicknesses based on the obtained amounts.

  Thereafter, the base 22 on which the surface layer 25 is formed is subjected to thermal oxidation in a muffle furnace at 300 ° C., 400 ° C., 500 ° C., and 600 ° C. in an air atmosphere for 30 minutes in step S15. Thus, the electrode 21 for electrolysis is obtained. Thereby, the tantalum metal constituting the surface layer 25 formed on the surface of the intermediate layer 24 is uniformly oxidized. In addition, since a tantalum metal is oxidized by the said thermal oxidation and becomes a tantalum oxide, the thickness of the surface layer 25 will be about 14 nm-2000 nm.

  Here, Ta is mentioned as a material constituting the surface layer 25. However, by changing this to W, the surface layer 25 is oxidized into tungsten oxide by thermal oxidation.

  FIG. 8 shows an X-ray diffraction pattern of the electrode 21 for electrolysis obtained as described above (surface layer 25 is made of tantalum oxide), and FIG. 9 shows an X-ray diffraction pattern of the electrode 21 for electrolysis obtained as described above. Tungsten oxide). Similar to the above embodiment, the crystal structure of tantalum oxide (tungsten oxide) constituting the surface layer 25 can be analyzed by using X-ray diffraction. Also in this example, observation was performed using an X-ray diffractometer (D8 Discover manufactured by Bruker AXS).

FIG. 8 shows X-ray diffraction patterns of the electrode 21 oxidized at 600 ° C., 500 ° C., 400 ° C., and 300 ° C. in order from the top. For comparison, an X-ray diffraction pattern of an electrode that does not constitute the surface layer 25 (surface is only Pt) is shown at the bottom. According to this, the electrode 21 having an oxidation temperature of 600 ° C. has a diffraction peak peculiar to tantalum oxide (Ta ₂ O ₅ ) (a peak indicated by a black circle in FIG. 8) and a diffraction peak peculiar to platinum constituting the intermediate layer 24 ( A peak indicated by * in FIG. 8 is observed. Therefore, it can be seen that, under this condition, the surface layer 25 is formed with crystalline tantalum oxide (Ta ₂ O ₅ ).

  In contrast, the electrode 21 having an oxidation temperature of 400 ° C. has a diffraction peak peculiar to tantalum oxide (TaO) (a peak indicated by a white circle in FIG. 8) and a diffraction peak peculiar to platinum. Therefore, it can be seen that under the conditions, the surface layer 25 is formed with crystalline tantalum oxide (TaO).

  Further, the electrode 21 having an oxidation temperature of 300 ° C. has a diffraction peak peculiar to tantalum (Ta) (a peak indicated by a black triangle in FIG. 8) and a diffraction peak peculiar to platinum. Therefore, it can be seen that part of the surface layer 25 remains as tantalum under the conditions.

  On the other hand, the electrode 21 having an oxidation temperature of 500 ° C. does not have the diffraction peak peculiar to tantalum oxide or tantalum as described above, but shows a diffraction peak peculiar to platinum and an amorphous state (amorphous). Is seen. Therefore, it can be seen that under the conditions, the surface layer 25 is formed of amorphous tantalum oxide. In addition, even when compared with the X-ray diffraction pattern of the platinum electrode shown in the comparison, it is easily understood that amorphous exists in the electrode under the condition.

FIG. 9 shows X-ray diffraction patterns of the electrode 21 oxidized at 600 ° C., 500 ° C., 400 ° C., and 300 ° C. in order from the top. In the same manner as described above, at the bottom, for comparison, an X-ray diffraction pattern of an electrode (surface is only Pt) that does not constitute the surface layer 25 is shown. According to this, the electrodes 21 having oxidation temperatures of 600 ° C., 500 ° C., and 400 ° C. all constitute a diffraction peak peculiar to tungsten oxide (WO ₃ ) (a peak indicated by a white circle in FIG. 9) and the intermediate layer 24. A diffraction peak peculiar to platinum (peak indicated by * in FIG. 9) is observed. Therefore, it can be seen that, under the conditions, the surface layer 25 is formed with crystalline tungsten oxide (WO ₃ ).

In contrast, the electrode 21 having an oxidation temperature of 300 ° C. does not have a diffraction peak peculiar to tungsten oxide (WO ₃ ) as described above, but only a diffraction peak peculiar to platinum. Therefore, it can be seen that, under the conditions, the surface layer 25 is formed of amorphous tungsten oxide.
(Electrolysis method using each electrode for electrolysis and its evaluation)
Next, generation of ozone by electrolysis using the electrode 1 for electrolysis manufactured as described above will be described with reference to FIG. FIG. 10 is a diagram showing the ozone generation current efficiency when using the electrode for electrolysis prepared under each condition. In the figure, black circles indicate the ozone generation current efficiency when the surface layer 25 is composed of tantalum oxide, and white circles indicate the ozone generation current efficiency when the surface layer 25 is composed of tungsten oxide. In addition, the said experimental result is obtained using the electrolyzer 10 in the said Example, Since it is the same as that of the above about the structure of this apparatus and an experimental condition, description is abbreviate | omitted.

  According to this, when the surface layer 25 is made of tantalum oxide, the ozone generation current efficiency is about 3.6% at an oxidation temperature of 300 ° C, about 6.6% at an oxidation temperature of 400 ° C, and at an oxidation temperature of 500 ° C. At an oxidation temperature of 300 ° C., it was about 2.4%. Here, the oxidation temperature of 300 ° C., the oxidation temperature of 400 ° C., and the oxidation temperature of 600 ° C. all have a tantalum oxide or tantalum crystal structure. On the other hand, at an oxidation temperature of 500 ° C., any amorphous tantalum oxide having no crystal structure is formed as the surface layer 25.

  From these results, it can be seen that when tantalum oxide is formed on the surface layer 25, the efficiency of ozone generation current is highest in the case of amorphous tantalum oxide that does not take a crystal structure.

  When the surface layer 25 is made of tungsten oxide, the ozone generation current efficiency is about 6.1% at an oxidation temperature of 300 ° C., about 2.4% at an oxidation temperature of 400 ° C., and 3 at an oxidation temperature of 500 ° C. When the oxidation temperature was about 300 ° C., it was about 4.2%. Here, the oxidation temperature of 400 ° C., the oxidation temperature of 500 ° C., and the oxidation temperature of 600 ° C. all have a tungsten oxide crystal structure. On the other hand, amorphous tungsten oxide having no crystal structure is formed as the surface layer 25 at an oxidation temperature of 300 ° C.

  From these results, it can be seen that when tungsten oxide is formed on the surface layer 25, the efficiency of ozone generation current is highest in the case of amorphous tungsten oxide that does not take a crystal structure.

  Next, an electrode for electrolysis according to Example 3 of the present invention will be described. In addition, since the manufacturing method of the electrode 31 for electrolysis obtained by the Example concerned is the same as that of the flowchart of FIG. 2 in the said Example 1, and a schematic block diagram is also substantially the same as FIG. 1, description of a detailed manufacturing method Is omitted.

  That is, in the electrode for electrolysis in this example, the adhesion layer 3 is composed of titanium oxide on the surface of silicon constituting the substrate by sputtering as in the above examples, and the intermediate layer is formed on the surface of the adhesion layer 3 by sputtering. 4 is made of platinum.

Next, the surface layer 5 is formed on the surface of the substrate 2 on which the intermediate layer 4 is formed. In this embodiment, since the surface layer 5 is formed using a spin coating method, an organic tantalum compound solution as a surface layer constituent material is applied to the surface of the substrate 2 on which the intermediate layer 4 is formed. In this embodiment, since the surface layer 5 is made of tantalum oxide, a Ta (OEt) ₅ solution is used in this embodiment. In this embodiment, ethyl acetate is used as a solvent for the Ta (OEt) ₅ solution. In this example, Ta (OEt) ₅ solution is used as the surface layer constituting material, but is not limited to this, and is a compound containing tantalum, which removes substances other than tantalum by firing, Any material that can be deposited with tantalum oxide is acceptable. In this embodiment, ethyl acetate is used as a solvent, but the present invention is not limited to this, and other solvents such as alcohols may be used.

  And the said surface layer constituent material is dripped at the surface of the base | substrate 2 in which the intermediate | middle layer 4 was formed, and a thin film is formed by the spin coat method. The conditions in the spin coating method in this example are set to 1000 rpm for 5 seconds and 3000 rpm for 15 seconds as in Example 1. Thereafter, drying is performed for 10 minutes each at room temperature and 200 ° C.

  Thereafter, the substrate 2 on which the intermediate layer 4 and the surface layer 5 are formed is fired (annealed) in a muffle furnace at 400 ° C. to 700 ° C. in an air atmosphere for 10 minutes to obtain an electrode for electrolysis. Thereby, the surface layer constituent material applied to the surface of the intermediate layer 4 is uniformly made of tantalum oxide.

  The surface layer 5 of the electrode 1 for electrolysis obtained as described above is all made of tantalum oxide. That is, the surface layer constituting material is baked as described above, for example, a compound other than tantalum, that is, a functional group composed of an organic substance, is removed. On the other hand, tantalum reacts with oxygen in the atmosphere to become tantalum oxide.

  FIG. 11 shows an X-ray diffraction pattern (surface layer 5 is made of tantalum oxide) of the electrode 1 for electrolysis obtained as described above. As in the above embodiments, the crystal structure of tantalum oxide constituting the surface layer 5 can be analyzed by using X-ray diffraction. Also in this example, observation was performed using an X-ray diffractometer (D8 Discover manufactured by Bruker AXS).

FIG. 11 shows X-ray diffraction patterns of the electrode 1 baked at 700 ° C., 600 ° C., 500 ° C., and 400 ° C. in order from the top. According to this, the diffraction peak (peak shown by a black circle in FIG. 11) peculiar to tantalum oxide (Ta ₂ O ₅ ) is observed in the electrodes 1 having the firing temperatures of 700 ° C. and 600 ° C. Therefore, it can be seen that, under the conditions, the surface layer 5 is formed with crystalline tantalum oxide (Ta ₂ O ₅ ).

On the other hand, the electrode 1 having the firing temperatures of 500 ° C. and 400 ° C. does not have the diffraction peak peculiar to tantalum oxide (Ta ₂ O ₅ ) as described above, and indicates that the electrode 1 is in an amorphous state (amorphous). Is seen. Therefore, it can be seen that under the conditions, the surface layer 5 is formed of amorphous tantalum oxide.
(Electrolysis method using each electrode for electrolysis and its evaluation)
Next, generation of ozone by electrolysis using the electrode 1 for electrolysis manufactured as described above will be described with reference to FIG. FIG. 12 is a diagram showing the ozone generation current efficiency when using the electrode for electrolysis prepared under each condition. In addition, the said experimental result is obtained using the electrolyzer 10 in the said Example, Since it is the same as that of the above about the structure and experimental condition of the said apparatus, description is abbreviate | omitted.

  According to this, at a firing temperature of 400 ° C, the ozone generation current efficiency is about 7.0%, at a firing temperature of 500 ° C, about 12.0%, at a firing temperature of 600 ° C, about 6.1%, and at a firing temperature of 700 ° C. It was about 4.6%. Here, the firing temperature of 600 ° C. and the firing temperature of 700 ° C. both have a tantalum oxide crystal structure. On the other hand, at the firing temperature of 500 ° C. and the firing temperature of 400 ° C., amorphous tantalum oxide having no crystal structure is formed as the surface layer 5.

  From this result, when tantalum oxide is formed on the surface layer 5, the ozone generation current efficiency is higher in the case of amorphous tantalum oxide that does not have a crystal structure than in the case where tantalum oxide having a crystal structure forms the surface layer 5. Is high.

  From the experimental results in Example 2 and Example 3, it is possible to generate ozone in the electrolyte solution by electrolyzing the electrolyte solution using the electrode for electrolysis as an anode, but the surface layer 5 (25 ) Is formed of amorphous tantalum oxide or amorphous tungsten oxide, the ozone generation efficiency is higher than when the surface layer is formed of crystalline tantalum oxide or tungsten oxide. I understand that it is expensive.

  This is because the amorphous type tantalum oxide or tungsten oxide is formed into a thin film, so that electrons are formed of a conductive material through impurity levels in the surface layer or by a Fowler-Nordheim tunnel. It is thought that it moves to the layer.

  In general, when a metal electrode is used as an electrode for electrolysis, an electrode reaction at the anode preferentially causes an oxygen generation reaction when an empty level immediately above the Fermi level receives electrons from the electrolyte. In addition, when the surface layer is composed of crystallized metal oxide, the metal segregates at the grain boundary between the crystals and current flows, so in this case as well, the electrode reaction at the anode is the Fermi level. An empty level immediately above the position receives electrons from the electrolyte, so that an oxygen generation reaction occurs preferentially.

  On the other hand, when an electrode for electrolysis having a surface layer formed as in each of the above examples is used, the surface layer is composed of an amorphous metal oxide such as amorphous tantalum oxide or tungsten oxide. The empty level near the bottom of the conductor, which is at an energy level about half the band gap higher than the Fermi level, receives electrons from the electrolyte, so that the oxygen generation reaction is suppressed more than the above, and ozone instead The production reaction takes place more efficiently.

  Therefore, when the electrode for electrolysis as shown in each of the above examples is used as an anode, the surface layer is formed of an electrode for electrolysis such as platinum or crystallized tantalum oxide (crystallized metal oxide). Compared to the case where the electrode for use is used, it is considered that the efficiency of ozone generation is increased because the movement of electrons at a higher energy level occurs and the ozone generation reaction occurs.

As a result, a predetermined low current density of 0.1 mA / cm ^{2 to} 2000 mA / cm ² , preferably 1 mA / cm ^{2 to} 1000 mA / cm ² is applied to the electrode 1 for electrolysis, thereby achieving high efficiency. It is possible to generate ozone. Further, ozone can be generated with high efficiency even when the temperature of the electrolyte solution is not particularly low and is a normal temperature such as + 15 ° C. as in this embodiment. Therefore, it is possible to reduce the power consumption required for ozone generation.

  In addition, the surface layer 5 of the electrode 1 capable of realizing ozone generation with high efficiency is not only formed by the sputtering method, but also formed by the spin coating method as described above. Therefore, the productivity can be further improved, and the electrode for electrolysis can be manufactured at a low manufacturing cost, and the cost of the equipment can be reduced.

  Furthermore, as described above, in each of the embodiments, the base 2 made of silicon is made of at least a hardly oxidizable metal, a metal oxide having conductivity, or a metal having conductivity even when oxidized. Since the electrode 1 for electrolysis is formed by forming the intermediate layer 4 including the above and further forming the surface layer 5 as described above on the surface of the intermediate layer 4, electrons effectively pass through the surface layer 5. It becomes possible to move. Therefore, an electrode reaction can occur at the surface of the surface layer 5 at a high energy level, and ozone can be efficiently generated at a lower current density.

  The base 2 is made of the same material as that of the intermediate layer 4, that is, a material containing at least a hardly oxidizable metal, a conductive metal oxide, or a metal that is conductive even when oxidized. In this case, it is possible to form an electrode that can generate ozone efficiently without forming the intermediate layer 4. However, by covering the substrate 2 with the intermediate layer 4 made of the above material as in the present invention, the electrode 1 that can generate ozone similarly can be realized at a low production cost. Is possible.

  Moreover, the electrode for electrolysis of the present invention shown in each of the above embodiments is not limited to that shown in the electrolysis apparatus 10, and may be used as an anode of an electrolysis unit 26 as shown in FIG. Good.

  That is, the electrolysis unit 26 as shown in FIG. 13 is composed of the electrolysis electrode 1 or 21 shown in each of the above embodiments constituting the anode, the electrode 28 constituting the cathode, and the cation exchange membrane 29. .

  The electrode 1 (or 21. anode) and the electrode 28 (cathode) are respectively formed with a plurality of water passage holes 27A and 28A for ensuring water permeability. These electrodes 1 and 28 are arranged on both surfaces of a cation exchange membrane (in this embodiment, Nafion (trade name) manufactured by DuPont) 29 to constitute an electrolysis unit 26.

  With this configuration, the electrolysis unit 26 is immersed in a treatment tank in which the electrolyte solution is stored, and a constant current having a predetermined current density is applied between the electrodes 1 and 28. Thereby, an appropriate zero gap is maintained between the electrode 1, the cation exchange membrane 29 and the electrode 28, and protons move through the cation exchange membrane 29, so that even if the electrolyte solution is pure water, It becomes possible to generate ozone efficiently. In addition, by allowing the gas generated from the water holes 27A and 28A to pass therethrough, it is possible to realize stable ozone generation.

It is a plane sectional view of the electrode for electrolysis of the present invention. (Example 1, Example 3) It is a flowchart of the manufacturing method of the electrode for electrolysis of this invention. (Example 1, Example 3) It is an X-ray diffraction pattern of the electrode for electrolysis of the present invention. Example 1 It is a schematic explanatory drawing of the electrolyzer of this invention. It is a figure which shows the ozone generation electric current efficiency at the time of using the electrode for electrolysis created by each condition. Example 1 It is a flowchart of the manufacturing method of the electrode for electrolysis of another Example. (Example 2) It is a plane sectional view of the electrode for electrolysis of other examples. (Example 2) It is an X-ray diffraction pattern of the electrode for electrolysis of the present invention. (Example 2) It is an X-ray diffraction pattern of the electrode for electrolysis of the present invention. (Example 2) It is a figure which shows the ozone generation electric current efficiency at the time of using the electrode for electrolysis created by each condition. (Example 2) It is an X-ray diffraction pattern of the electrode for electrolysis of the present invention. (Example 3) It is a figure which shows the ozone generation electric current efficiency at the time of using the electrode for electrolysis created by each condition. (Example 3) It is a schematic explanatory drawing of the electrolysis unit to which the electrode for electrolysis of the present invention is applied.

Explanation of symbols

1,21 Electrode for electrolysis (anode)
2, 22 Base body 3, 23 Adhesion layer 4, 24 Intermediate layer 5, 25 Surface layer 6 Titanium plate (electric conduction part)
7 Silver paste 8 Sealing material 10 Electrolyzer 11 Treatment tank 12, 28 Electrode (cathode)
13 Simulated tap water 14, 29 Cation exchange membrane 15 Power supply 26 Electrolysis unit 27A, 28A Water flow hole

Claims (7)

An electrode for electrolysis comprising a substrate and a surface layer formed on the surface of the substrate,
The electrode for electrolysis, wherein the surface layer is an amorphous insulator.   The electrode for electrolysis according to claim 1, wherein the insulator is a single metal oxide or a composite metal oxide.   The electrode for electrolysis according to claim 1 or 2, wherein the insulator is tantalum oxide or tungsten oxide.   The electrode for electrolysis according to claim 1 or 2, wherein the insulator is aluminum oxide.   The electrode for electrolysis according to any one of claims 1 to 4, wherein the surface layer has a thickness of 20 nm or more and 2000 nm or less.   6. The electrolyzer according to claim 1, wherein an intermediate layer is formed of a hardly oxidizable metal on the surface of the base body on the surface of the base body. electrode. An electrode having water permeability is constituted by the electrode for electrolysis according to any one of claims 1 to 6, and the anode and the cathode having water permeability are arranged on both surfaces of a cation exchange membrane. Electrolytic unit to be used.

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