WO2023188992A1

WO2023188992A1 - Electrode for electrolysis and hypochlorous acid generation device

Info

Publication number: WO2023188992A1
Application number: PCT/JP2023/005952
Authority: WO
Inventors: 直樹知念; 博史足立; 宜弘伊藤
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2022-03-31
Filing date: 2023-02-20
Publication date: 2023-10-05

Abstract

The present invention addresses the problem of providing: an electrode for electrolysis, the electrode being capable of achieving improved durability; and a hypochlorous acid generation device. According to the present invention, a catalyst layer (4) in an electrode (1) for electrolysis contains platinum and iridium oxide. A tantalum oxide layer (5) is provided on the catalyst layer (4). With respect to the electrode (1) for electrolysis, a part of the catalyst layer (4) is exposed. The catalyst layer (4) is a porous layer that contains a plurality of composite particles (41) and a plurality of pores (42). Each one of the plurality of composite particles (41) contains platinum and iridium oxide. The electrode (1) for electrolysis comprises a tantalum oxide part (43) which is provided within at least one pore (42) among the plurality of pores (42) of the catalyst layer (4) so as to be in contact with the catalyst layer (4); and the catalyst layer (4) comprises a region wherein the concentration of tantalum oxide in a composite layer, which comprises the catalyst layer (4) and a plurality of tantalum oxide parts (43), increases from a main surface (40) of the catalyst layer (4) toward a conductive substrate (2) in the thickness direction of the catalyst layer (4).

Description

Electrolytic electrodes and hypochlorous acid generating equipment

The present disclosure relates to an electrolytic electrode and a hypochlorous acid generating device, and more particularly to an electrolytic electrode containing iridium oxide and platinum, and a hypochlorous acid generating device equipped with the electrolytic electrode.

Conventionally, an electrolytic electrode used to generate chlorine by electrolyzing salt water is known (Patent Document 1).

Patent Document 1 discloses a conductive substrate containing at least titanium, an intermediate layer provided on the conductive substrate and containing platinum, and a catalyst layer provided on the intermediate layer and containing platinum and iridium oxide. An electrode for electrolysis comprising the following is disclosed.

Further improvement in durability is desired for electrodes for electrolysis.

International Publication No. 2021/117311

An object of the present disclosure is to provide an electrolytic electrode and a hypochlorous acid generating device that can improve durability.

An electrolysis electrode according to one aspect of the present disclosure includes a conductive substrate, an intermediate layer, a catalyst layer, and a tantalum oxide layer. The conductive substrate has a first main surface and a second main surface opposite to the first main surface. The conductive substrate includes at least titanium. The intermediate layer is provided on the first main surface of the conductive substrate. The intermediate layer includes platinum. The catalyst layer is provided on the intermediate layer. The catalyst layer contains platinum and iridium oxide. The tantalum oxide layer is provided on the catalyst layer. In the electrolysis electrode, a part of the catalyst layer is exposed. The catalyst layer is a porous layer including a plurality of composite particles and a plurality of pores. Each of the plurality of composite particles contains platinum and iridium oxide. The electrolysis electrode further includes a plurality of tantalum oxide parts provided in at least one of the plurality of pores and in contact with the catalyst layer. In the electrolysis electrode, the concentration of tantalum oxide in the composite layer including the catalyst layer and the plurality of tantalum oxide parts increases as it approaches the conductive substrate from the main surface of the catalyst layer in the thickness direction of the catalyst layer. Contains the area to

A hypochlorous acid generating device according to one aspect of the present disclosure includes a container into which salt water is placed, and a first electrode and a second electrode arranged in the container so as to be in contact with the salt water. At least one of the first electrode and the second electrode includes the electrolysis electrode.

FIG. 1A is a schematic cross-sectional view of an electrode for electrolysis according to an embodiment. FIG. 1B is an explanatory diagram of main parts of the electrolytic electrode same as above. FIG. 2 is an explanatory diagram of particles contained in the catalyst layer of the electrolytic electrode same as above. FIG. 3A is a cross-sectional view of the electrolytic electrode same as above. FIG. 3B is a schematic diagram of the concentration distribution of tantalum oxide in a composite layer including a catalyst layer and a plurality of tantalum oxide parts in the electrolysis electrode described above. FIG. 4 is a schematic diagram of a profile of the amount of tantalum oxide in the depth direction of the electrode for electrolysis. FIG. 5 is a schematic diagram of another example of the depth profile of the amount of tantalum oxide in the electrolysis electrode as described above. FIG. 6 is a schematic diagram of still another example of the depth profile of the amount of tantalum oxide in the electrolytic electrode described above. FIG. 7 is a schematic diagram of a hypochlorous acid generating device equipped with the same electrolytic electrode as above.

1A to 7 described in the embodiments below are schematic diagrams, and the size and thickness ratios of each component in the diagrams do not necessarily reflect the actual dimensional ratios. do not have.

(Embodiment)
Hereinafter, the electrolysis electrode 1 according to the embodiment will be described based on FIGS. 1A to 4.

(1) Overview The electrolysis electrode 1 is an electrode used to generate chlorine by electrolyzing salt water. Here, the salt water is, for example, salt water. When the electrolytic electrode 1 is used for electrolyzing salt water, for example, by using the electrolytic electrode 1 as the anode of the anode and cathode to which a DC voltage is applied from the power supply, the salt water is electrolyzed to produce chlorine. can be generated, and hypochlorous acid water can be generated by the reaction between this chlorine and water.

(2) Components of Electrolytic Electrode As shown in FIG. 1A, the electrolytic electrode 1 includes a conductive substrate 2, an intermediate layer 3, a catalyst layer 4, and a tantalum oxide layer 5. Intermediate layer 3 is provided on conductive substrate 2 . The catalyst layer 4 is provided on the intermediate layer 3. That is, the intermediate layer 3 is a layer interposed between the conductive substrate 2 and the catalyst layer 4. Tantalum oxide layer 5 is provided on catalyst layer 4 .

Hereinafter, each component of the electrolytic electrode 1 will be explained in more detail.

(2.1) Conductive Substrate The planar shape of the conductive substrate 2 (the outer peripheral shape when the conductive substrate 2 is viewed from the thickness direction of the conductive substrate 2) is, for example, rectangular. The thickness of the conductive substrate 2 is, for example, 100 μm or more and 2 mm or less, and is, for example, 500 μm. The size of the conductive substrate 2 in plan view is, for example, 25 mm x 60 mm. The conductive substrate 2 has a first main surface 21 and a second main surface 22 opposite to the first main surface 21 .

The conductive substrate 2 contains at least titanium. The material of the conductive substrate 2 includes titanium or an alloy containing titanium as a main component (hereinafter referred to as titanium alloy). Examples of the titanium alloy include titanium-palladium alloy, titanium-nickel-ruthenium alloy, titanium-tantalum alloy, titanium-aluminum alloy, titanium-aluminum-vanadium alloy, and the like. For example, as shown in FIGS. 3A and 3B, the conductive substrate 2 includes a titanium substrate 20 and a titanium oxide layer 24 formed on the titanium substrate 20 and having conductivity. The first main surface 21 of the conductive substrate 2 includes a surface 241 of the titanium oxide layer 24 on the opposite side to the titanium substrate 20 side. The resistivity of the titanium oxide layer 24 is 10 5 Ωcm or less, and the smaller the difference from the resistivity of the titanium substrate 20, the better.

The first main surface 21 of the conductive substrate 2 is preferably a rough surface from the viewpoint of improving the adhesion of the intermediate layer 3. In the electrolysis electrode 1 according to the embodiment, the first main surface 21 of the conductive substrate 2 is roughened before the intermediate layer 3 is provided. Here, regarding the surface roughness of the first main surface 21 of the conductive substrate 2, the arithmetic mean roughness Ra is, for example, 0.7 μm, and the maximum height Rz is 7 μm. The arithmetic mean roughness Ra and the maximum height Rz are defined in, for example, JIS B 0601-2001 (ISO 4287-1997). The arithmetic mean roughness Ra and the maximum height Rz are, for example, values measured from a cross-sectional SEM image (Cross-sectional Scanning Electron Microscope Image).

(2.2) Intermediate layer The intermediate layer 3 is provided on the first main surface 21 of the conductive substrate 2, as shown in FIG. 1A. Therefore, the electrolysis electrode 1 has an interface between the conductive substrate 2 and the intermediate layer 3. Further, the intermediate layer 3 has a main surface 30 (see FIGS. 3A and 3B) on the opposite side of the intermediate layer 3 to the conductive substrate 2 side. The intermediate layer 3 is preferably formed of a material that has higher corrosion resistance to salt water and chlorine than the conductive substrate 2. Moreover, from the viewpoint of increasing the electrical conductivity of the entire electrolytic electrode 1, it is preferable that the material of the intermediate layer 3 is electrically conductive and has high electrical conductivity. The material of the intermediate layer 3 is, for example, a transition metal or a mixture containing a transition metal, such as platinum, a mixture of tantalum, platinum, and iridium. The material of the intermediate layer 3 is platinum, for example.

The thickness of the intermediate layer 3 is, for example, 0.3 μm or more and 5 μm or less, and is, for example, 0.6 μm.

Furthermore, it is desirable that the main surface 30 of the intermediate layer 3 on the side opposite to the conductive substrate 2 side maintains the surface roughness of the conductive substrate 2 underlying the intermediate layer 3.

(2.3) Catalyst Layer The catalyst layer 4 is provided on the intermediate layer 3, as shown in FIG. 1A. The electrolytic electrode 1 has an interface between a catalyst layer 4 and an intermediate layer 3. That is, the catalyst layer 4 is provided on the conductive substrate 2 with the intermediate layer 3 interposed therebetween.

The catalyst layer 4 contains platinum and iridium oxide. The catalyst layer 4 is a porous layer including a plurality of composite particles 41 and a plurality of pores 42, as shown in FIGS. 1B and 3A. Each of the plurality of composite particles 41 includes platinum particles 411 and iridium oxide particles 412, as shown in FIG. In each of the plurality of composite particles 41, for example, a plurality of iridium oxide particles 412 are bonded to one platinum particle 411. In the catalyst layer 4, iridium oxide is dispersed by platinum. Iridium oxide functions as a catalyst to generate chlorine. The catalyst layer 4 may contain iridium in addition to platinum and iridium oxide. In this case, in the composite particles 41, iridium particles in addition to the iridium oxide particles 412 may be bonded to the platinum particles 411. Further, in the catalyst layer 4, the platinum particles 411 may be bonded to each other. The bonding state in the catalyst layer 4 is not particularly limited.

As shown in FIGS. 1A, 1B, and 3B, the catalyst layer 4 has a plurality of recesses 45 recessed from the main surface 40 on the opposite side to the conductive substrate 2 side. In the electrolysis electrode 1, a portion of the catalyst layer 4 is exposed by the plurality of recesses 45. Each of the plurality of recesses 45 is, for example, a crack formed in the catalyst layer 4. More specifically, each of the plurality of recesses 45 is a linear crack when viewed from above in the thickness direction of the catalyst layer 4 . The shapes of the plurality of cracks (recesses 45) are different from each other.

The depth of each of the plurality of recesses 45 is, for example, 0.1 μm or more. The depth of each of the plurality of recesses 45 may be a depth that reaches the intermediate layer 3 or may be a depth that does not reach the intermediate layer 3. In the electrolysis electrode 1 according to the embodiment, the plurality of recesses 45 are not formed to penetrate the intermediate layer 3, and the entire first main surface 21 of the conductive substrate 2 is covered with the intermediate layer 3. There is. In plan view from the thickness direction of the conductive substrate 2, the width of each of the plurality of recesses 45 is 0.1 μm or more and 10 μm or less, and more preferably 0.3 μm or more and 3 μm or less. The width of the recess 45 in a plan view from the thickness direction of the conductive substrate 2 is the opening width in the lateral direction (direction perpendicular to the longitudinal direction) on the main surface 40 of the catalyst layer 4. In plan view from the thickness direction of the conductive substrate 2, the length of each of the plurality of recesses 45 is shorter than the length of each side of the conductive substrate 2.

The thickness of the catalyst layer 4 is, for example, 0.1 μm or more and 10 μm or less.

(2.4) Tantalum Oxide Layer The tantalum oxide layer 5 (see FIGS. 1A, 1B, 3A, and 3B) has a function of suppressing elution of at least one of iridium oxide and platinum from the catalyst layer 4.

As shown in FIG. 1B, the tantalum oxide layer 5 includes a first portion 51 provided on the main surface 40 of the catalyst layer 4 and an inner surface 451 of at least one recess 45 among the plurality of recesses 45 in the catalyst layer 4. a second portion 52 provided thereon. Preferably, the tantalum oxide layer 5 has a second portion 52 on the inner surface 451 of each of the plurality of recesses 45 in the catalyst layer 4 .

(2.5) Tantalum oxide portion As shown in FIGS. 1B and 3A, the electrolysis electrode 1 includes tantalum oxide, which is provided in at least one pore 42 among the plurality of pores 42 of the catalyst layer 4 and is in contact with the catalyst layer 4. It further includes a section 43. The tantalum oxide portion 43 is formed, for example, when the tantalum oxide layer 5 is formed. The tantalum oxide portion 43 is in contact with the composite particles 41 of the catalyst layer 4. It is preferable that at least one tantalum oxide part 43 among the plurality of tantalum oxide parts 43 penetrates the intermediate layer 3 and is in contact with the titanium oxide layer 24 .

(2.6) Composite layer including a catalyst layer and a plurality of tantalum oxide parts The electrolytic electrode 1 has tantalum oxide as it approaches the conductive substrate 2 from the main surface 40 of the catalyst layer 4 in the thickness direction of the catalyst layer 4. Contains areas of increasing volume. In FIG. 3B, hatching is applied so that the area with more tantalum oxide has a higher dot density. The hatching in FIG. 3B is not hatching indicating a cross section. In the electrolytic electrode 1, for example, as shown in FIG. 4, the amount of tantalum oxide changes stepwise in the thickness direction of the catalyst layer 4, and It includes a region where the amount of tantalum oxide increases as it approaches the first main surface 21 of the conductive substrate 2 from the surface 40. Here, the amount of tantalum oxide increases as the concentration of tantalum oxide in the composite layer including the catalyst layer 4 and the plurality of tantalum oxide parts 43 increases. Therefore, "the amount of tantalum oxide is changing stepwise" can be translated as "the concentration of tantalum oxide in the composite layer including the catalyst layer 4 and a plurality of tantalum oxide parts 43 is changing stepwise". It's okay. Moreover, "a region where the amount of tantalum oxide increases" may be rephrased as "a region where the concentration of tantalum oxide in the composite layer including the catalyst layer 4 and a plurality of tantalum oxide parts 43 increases."

By the way, the inventors of the present invention manufactured a plurality of electrolytic electrodes using the amount of tantalum oxide in the composite layer as a parameter, conducted a durability test on each of the plurality of electrolytic electrodes, and evaluated the initial amount of chlorine generation and deterioration rate. did.

The durability test is an accelerated test. In the durability test, two electrolytic electrodes made under the same conditions were used as a pair of electrodes, and the pair of electrodes was immersed in salt water in an electrolytic bath in a durability test facility, and initial aging was performed by energizing the pair of electrodes. Then, each time a pair of electrodes is continuously energized for a predetermined period of time, the pair of electrodes is immersed in salt water in an electrolytic bath for measuring chlorine concentration, and the current is energized for a predetermined period of time (3 minutes). The (average value) of chlorine concentration was measured. Here, the electrolytic cell of the durability test equipment has a salt water inlet and a drain outlet. In the durability test, salt water was added so that the conductivity of the salt water in the electrolytic cell of the durability test equipment was 1650±200 μS/m. In addition, in the durability test, tap water was constantly supplied to the electrolytic cell of the durability test equipment at a flow rate of 2 L/min while draining water. The brine supplied to the electrolytic cell of the durability testing facility is a brine produced by dissolving common salt (sodium chloride) in tap water. The current value of the current applied in the durability test was 400 mA. As the salt water in the electrolytic cell for measuring chlorine concentration, the salt water produced by dissolving 4.5 g of common salt (sodium chloride) in 800 mL of pure water was used. The current value of the current flowing in the chlorine concentration measurement was 400 mA. In addition, in the initial aging, the polarity was reversed every time the current was applied between the pair of electrodes for a predetermined period of time (3 minutes), and the pair of electrodes was energized for a total of 12 minutes. Here, polarity reversal means reversing the combination of an anode and a cathode in a pair of electrodes. In other words, polarity reversal refers to changing the electrode used as an anode and the electrode used as a cathode to become a cathode and an anode, respectively, which is the higher potential side of a pair of electrodes. means.

The initial amount of chlorine generated is the amount of chlorine generated per unit time in the durability test when energization of the pair of electrodes is started after initial aging. The deterioration rate is the value obtained by dividing the difference between the initial amount of chlorine generated and the amount of chlorine generated when the durability test time (elapsed time) after initial aging is 200 hours, divided by the initial amount of chlorine generated.

A predictive profile showing the relationship between the amount of tantalum oxide and the initial amount of chlorine generation was derived by performing multiple regression analysis on the amount of chlorine generated in durability tests of electrolytic electrodes prepared under various conditions. In addition, multiple regression analysis was performed on the deterioration rates obtained in durability tests of electrolytic electrodes prepared under various conditions, and a predictive profile showing the relationship between the amount of tantalum oxide and the deterioration rate was derived.

As a result, it was found that the larger the amount of tantalum oxide, the less the initial amount of chlorine generated. It was also found that the higher the amount of tantalum oxide, the higher the rate of deterioration.

However, if the amount of tantalum oxide is reduced, the mechanical strength of the catalyst layer 4 will decrease, and the catalyst layer 4 will easily peel off from the conductive substrate 2 side. Therefore, as shown in FIG. 4, the electrolytic electrode 1 according to the embodiment has a region in which the amount of tantalum oxide increases as it approaches the conductive substrate 2 from the main surface 40 of the catalyst layer 4 in the thickness direction of the catalyst layer 4. is configured to include. The fact that there is a region where the amount of tantalum oxide increases in the thickness direction of the catalyst layer 4 can be found by, for example, performing energy dispersive X-ray analysis in a cross-sectional view. Further, it can be seen from, for example, a composition analysis using XPS (X-ray Photoelectron Spectroscopy) that there is a region where the amount of tantalum oxide increases in the thickness direction of the catalyst layer 4.

(3) Method for manufacturing electrode for electrolysis A method for manufacturing electrode for electrolysis 1 will be briefly described.

In the method for manufacturing the electrolytic electrode 1, first, the conductive substrate 2 is prepared, and then a surface roughening step, an intermediate layer forming step, a catalyst layer forming step, and a tantalum oxide layer forming step are sequentially performed.

In the surface roughening step, the first main surface 21 of the conductive substrate 2 is roughened, for example, by immersing the conductive substrate 2 in an oxalic acid aqueous solution.

In the intermediate layer forming step, the intermediate layer 3 is formed on the first main surface 21 of the conductive substrate 2. In the intermediate layer forming step, a paste material produced by mixing platinum particles or an organic metal component containing platinum with a resin binder component and a solvent is applied onto the first main surface 21 of the conductive substrate 2 by screen printing. Then, the intermediate layer 3 is formed by drying the solvent component at 200 to 300° C., and then performing baking at about 800 to 1000° C. to remove the resin binder component and sinter the platinum particles.

In the catalyst layer forming step, the catalyst layer 4 is formed on the intermediate layer 3. The catalyst layer forming process includes a first step and a second step.

In the first step of the catalyst layer forming process, for example, a layer of catalyst material, which is the source of the catalyst layer 4, is formed on the intermediate layer 3 on the conductive substrate 2 by performing a plurality of coating steps and a plurality of drying steps. form. The number of times of the coating process and the drying process is determined depending on, for example, the predetermined thickness of the catalyst layer 4, the thickness of the region where the amount of iridium oxide increases in the thickness direction of the catalyst layer 4, the rate of change in the amount of iridium oxide, etc. It can be decided. Regarding the number of times of the coating process and drying process, the thicker the predetermined thickness of the catalyst layer 4, the more the number of times of the coating process and drying process may be increased. For example, in the catalyst layer forming step, the catalyst layer 4 is formed on the intermediate layer 3 on the conductive substrate 2 by alternately repeating the coating step a first prescribed number of times and the drying step the first prescribed number of times. Form the base catalyst material layer.

In the first step of the catalyst layer forming process, a solution (hereinafter referred to as the first solution) containing a platinum compound and an iridium compound that will become the source of the catalyst layer 4 is directly or indirectly deposited on the intermediate layer 3 on the conductive substrate 2. ) is applied (after the coating process is performed) and then heat treatment (drying process) is performed under the first condition to form a catalyst material layer that will become the basis of the catalyst layer 4. do. The first solution is a solution in which a platinum compound and an iridium compound are mixed in a solvent (hereinafter referred to as the first solvent). The first solvent is, for example, a liquid mixture of ethylene glycol monoethyl ether, hydrochloric acid, and ethanol. The platinum compound is, for example, chloroplatinic acid, but is not limited thereto, and may be, for example, platinum chloride. Chloroplatinic acid is, for example, hexachloroplatinic (IV) acid n-hydrate. The iridium compound is, for example, chloroiridic acid, but is not limited thereto, and may be, for example, iridium chloride or iridium nitrate. Chloroiridic acid is, for example, hexachloroiridic (IV) acid n-hydrate. The metal concentration (total concentration of platinum and iridium) of the first solution is, for example, 10 to 50 mg/mL. Further, the amount of the first solution applied is, for example, 2 to 5 μL/cm ² . The first condition includes a heat treatment temperature and a heat treatment time. The heat treatment temperature under the first condition is, for example, 100°C to 400°C. Further, the heat treatment time under the first condition is, for example, 5 minutes to 15 minutes.

In the second step of the catalyst layer forming process, the catalyst layer 4 and a plurality of cracks (recesses 45) are formed by performing heat treatment to fire the catalyst material layer under predetermined firing conditions. The firing conditions include firing temperature and firing time. The firing temperature is, for example, 300°C to 600°C. The firing time is, for example, 5 minutes to 20 minutes.

In the tantalum oxide layer forming step, a tantalum oxide layer 5 is formed on the catalyst layer 4. The tantalum oxide layer forming step includes a first step and a second step.

In the first step of the tantalum oxide layer process, a material layer that becomes the source of the tantalum oxide layer 5 is formed on the catalyst layer 4 by performing at least two coating processes and at least two drying processes. The number of times of the coating process and the drying process is determined depending on the predetermined thickness of the tantalum oxide layer 5, for example. Regarding the number of times of the coating process and drying process, the thicker the predetermined thickness of the tantalum oxide layer 5, the more the number of times of the coating process and drying process may be increased. For example, in the tantalum oxide layer forming step, a material layer that becomes the source of the tantalum oxide layer 5 is formed on the catalyst layer 4 by performing a second specified number of coating steps and a second specified number of drying steps.

In the first step of the tantalum oxide layer forming process, a solution containing a tantalum compound (hereinafter referred to as the second solution) that is the source of the tantalum oxide layer 5 is applied onto the catalyst layer 4 (after the application process is performed). By performing heat treatment (drying step) of heating and drying under the second conditions at least twice, a material layer that will become the basis of the tantalum oxide layer 5 is formed. The second solution is a solution in which a tantalum compound is dissolved in a solvent (hereinafter referred to as a second solvent). The second solvent is, for example, a liquid mixture of ethylene glycol monoethyl ether, hydrochloric acid, and ethanol. The tantalum compound is, for example, tantalum chloride, but is not limited thereto, and may be, for example, tantalum ethoxide. The metal concentration (tantalum concentration) of the second solution is, for example, 10 to 50 mg/L. Further, the amount of the second solution applied is, for example, 1 to 5 μL/cm ² . At this time, the metal concentration in the second solution applied for the second time needs to be lower than the metal concentration in the second solution applied for the first time (for example, if the metal concentration is 30 mg/L for the first time) (The second metal concentration is 20 mg/L.) Alternatively, the amount of the second solution applied at the second time needs to be smaller than the amount of the second solution applied at the first time (for example, if the amount of the second solution applied at the first time is 2 μL/ ^cm2 , The amount of second solution applied for the second time is 1 μL/cm ² ). The second conditions include heat treatment temperature and heat treatment time. The heat treatment temperature under the second condition is, for example, 100°C to 400°C. Further, the heat treatment time under the second condition is, for example, 5 minutes to 15 minutes.

In the second step of the tantalum oxide layer forming process, the tantalum oxide layer 5 is formed by performing heat treatment to fire the material layer under predetermined firing conditions. The firing conditions include firing temperature and firing time. The firing temperature is, for example, 500°C to 600°C. The firing time is, for example, 5 minutes to 20 minutes.

In the method for manufacturing the electrolytic electrode 1 described above, the tantalum oxide portions 43 within the pores 42 in the catalyst layer 4 are formed in the tantalum oxide layer forming step. In the method for manufacturing the electrolytic electrode 1, by performing the tantalum oxide layer forming step described above, it is possible to create a region where the amount of tantalum oxide increases from the main surface 40 of the catalyst layer 4 toward the conductive substrate 2.

Note that the surface roughening step, the intermediate layer forming step, the catalyst layer forming step, and the tantalum oxide layer forming step are performed on a multi-layer substrate that includes a plurality of conductive substrates 2 and is capable of forming a large number of conductive substrates 2. You can also go to In this case, for example, a plurality of electrolytic electrodes 1 may be obtained by separating the multi-chip substrate into individual conductive substrates 2 after the tantalum oxide layer forming step.

(4) Summary The electrolysis electrode 1 according to the embodiment includes a conductive substrate 2, an intermediate layer 3, a catalyst layer 4, and a tantalum oxide layer 5. The conductive substrate 2 has a first main surface 21 and a second main surface 22 opposite to the first main surface 21 . Conductive substrate 2 contains at least titanium. Intermediate layer 3 is provided on first main surface 21 of conductive substrate 2 . Intermediate layer 3 contains platinum. The catalyst layer 4 is provided on the intermediate layer 3. Catalyst layer 4 contains platinum and iridium oxide. Tantalum oxide layer 5 is provided on catalyst layer 4 . In the electrolysis electrode 1, a part of the catalyst layer 4 is exposed. The catalyst layer 4 is a porous layer including a plurality of composite particles 41 and a plurality of pores 42 . Each of the plurality of composite particles 41 includes platinum (platinum particles 411) and iridium oxide (iridium oxide particles 412). The electrolysis electrode 1 includes a plurality of tantalum oxide parts 43 provided in at least one of the plurality of pores 42 of the catalyst layer 4 and in contact with the catalyst layer 4, and includes a plurality of tantalum oxide parts 43 in the thickness direction of the catalyst layer 4. Since the layer 4 includes a region in which the concentration of tantalum oxide in the composite layer including the catalyst layer 4 and a plurality of tantalum oxide parts 43 increases as it approaches the conductive substrate 2 from the main surface 40, durability can be improved. It becomes possible. More specifically, the electrolytic electrode 1 according to the embodiment includes tantalum oxide portions 43 provided in the plurality of pores 42 of the catalyst layer 4 and in contact with the catalyst layer 4, and the catalyst Since the area includes a region where the concentration of tantalum oxide in the composite layer including the catalyst layer 4 and a plurality of tantalum oxide parts 43 increases as it approaches the conductive substrate 2 from the main surface 40 of the layer 4, the initial amount of chlorine generated during use is reduced. It is possible to increase the mechanical strength of the catalyst layer 4 while suppressing a decrease in ), it is possible to improve the adhesion with The durability of the electrolysis electrode 1 can be improved by improving the adhesion between the catalyst layer 4 and the member supporting the catalyst layer 4.

Furthermore, in the electrolysis electrode 1 according to the embodiment, the conductive substrate 2 includes a titanium substrate 20 and a titanium oxide layer 24 that is formed on the titanium substrate 20 and has conductivity. The first main surface 21 of the conductive substrate 2 includes a surface 241 of the titanium oxide layer 24 on the opposite side to the titanium substrate 20 side. At least one tantalum oxide part 43 among the plurality of tantalum oxide parts 43 penetrates the intermediate layer 3 and is in contact with the titanium oxide layer 24 . Thereby, the electrolysis electrode 1 according to the embodiment can further improve durability.

(5) Modification of Embodiment The depth profile of the amount of tantalum oxide in the electrolysis electrode 1 is, for example, as shown in FIG. The profile may include a region where the amount of tantalum oxide increases continuously (linearly in FIG. 5) as it approaches the first main surface 21 of the conductive substrate 2.

Further, the depth direction profile of tantalum oxide in the electrolytic electrode 1 is, for example, as shown in FIG. In addition to a region where the amount of tantalum oxide increases continuously (in FIG. 6, linearly) as it approaches the surface 21, there is a region where the amount of tantalum oxide is constant at a relatively low value, and a region where the amount of tantalum oxide increases continuously (in FIG. 6, linearly). It may include at least one (in FIG. 6, both) of a region where the value is relatively high and constant.

(6) Hypochlorous acid generating device equipped with an electrode for electrolysis according to the embodiment As shown in FIG. It includes a first electrode 101A and a second electrode 101B that are arranged in the container 110 so as to be in contact with each other. In the hypochlorous acid generating device 100, both the first electrode 101A and the second electrode 101B include the electrolysis electrode 1, but at least one of the first electrode 101A and the second electrode 101B includes the electrolysis electrode 1. It is sufficient if it contains

The hypochlorous acid generating device 100 further includes, for example, a rectangular box-shaped main body case 102. Main body case 102 includes four side walls, a top wall, and a bottom wall. In the main body case 102, one of the two pairs of side walls facing each other among the four side walls has an air inlet 103, and the upper wall has an outlet 104 for blowing out air containing hypochlorous acid. ing. In FIG. 7, a flow path 105 for air that is sucked in from the suction port 103 and blown out from the blow-off port 104 is schematically shown with a border arrow. The container 110 is disposed within the main case 102 at the lower part of the main case 102. The container 110 is a tray (a container without a lid). The hypochlorous acid generating device 100 further includes a water tank 108 disposed within the main body case 102. The water supply tank 108 supplies water W1 in the water supply tank 108 to the container 110. The container 110 and the water tank 108 are detachably attached to the main case 102.

In addition, the hypochlorous acid generating device 100 further includes an operation switch for instructing the start and stop of operation of the hypochlorous acid generating device 100. The operation switch is arranged, for example, on the upper wall of the main body case 102.

The hypochlorous acid generating device 100 further includes a blower 106 that blows air from an inlet 103 toward an outlet 104, and a filter 107. The filter 107 is a rotatable tubular (cylindrical) filter, and can be impregnated with electrolyzed water containing hypochlorous acid so that the air passing through the filter 107 comes into contact with the electrolyzed water.

The blower 106 is arranged inside the main case 102 at the upper part of the main case 102. The blower 106 includes, for example, a sirocco fan.

The water tank 108 is attached to the container 110. The water supply tank 108 includes an opening for water supply and an on-off valve that opens and closes the opening. In the hypochlorous acid generating device 100, when the water supply tank 108 is attached to the container 110, the opening/closing valve section of the water supply tank 108 opens the opening, so that water W1 in the water supply tank 108 is supplied to the container 110. In the hypochlorous acid generating device 100, when the opening of the water tank 108 is submerged in the water in the container 110, air cannot enter into the water tank 108, and the on-off valve closes due to the gravity of the water W1 in the water tank 108. The water W1 in the water supply tank 108 is no longer supplied to the container 110.

In the hypochlorous acid generating device 100, an electrolytic auxiliary agent (for example, tablet-shaped sodium chloride) is added to the water in the container 110, so that the electrolytic auxiliary agent is dissolved, and the electrolytic auxiliary agent is dissolved in salt water (sodium chloride aqueous solution) in the container 110. ) is generated.

The filter 107 is arranged at the lower part of the main case 102 so that a part thereof is immersed in the liquid in the container 110. The filter 107 has a cylindrical shape, and is rotated about the central axis of the cylindrical filter 107 so that the portion immersed in the liquid in the container 110 changes. Filter 107 is rotated by a motor. The filter 107 is a filter capable of retaining electrolyzed water generated from the salt water 112 in the container 110 and allowing air to pass therethrough.

In addition, the hypochlorous acid generating device 100 further includes a water level sensor 109 that is disposed inside the container 110 and detects the water level of water or salt water in the container 110 and a drought.

In addition, the hypochlorous acid generating device 100 further includes a control device 114 that controls the operation of the hypochlorous acid generating device 100, and a humidity sensor 113. An operation switch, a water level sensor 109, and a humidity sensor 113 are connected to the control device 114. Further, the control device 114 is connected to a motor that rotates the filter 107, a blower 106, a first electrode 101A, and a second electrode 101B. The control device 114 controls the filter 107, the blower 106, the first electrode 101A, and the second electrode 101B based on signals from the operation switch, the water level sensor 109, the humidity sensor 113, and the like. The control device 114 controls the voltage applied between the first electrode 101A and the second electrode 101B. Thereby, the hypochlorous acid generating device 100 can generate electrolyzed water containing hypochlorous acid by electrolyzing the salt water 112. In the hypochlorous acid generating device 100, by impregnating the filter 107 with electrolyzed water and then blowing air with the blower 106, the air that has come into contact with the electrolyzed water through the filter 107 can be blown out from the outlet 104. . Control device 114 includes, for example, a computer system. A computer system mainly consists of a processor and a memory as hardware. The function of the control device 114 is realized by the processor executing a program recorded in the memory of the computer system. The program may be pre-recorded in the memory of the computer system, may be provided through a telecommunications line, or may be recorded on a non-transitory storage medium readable by the computer system, such as a memory card, optical disc, hard disk drive, etc. may be provided. A processor in a computer system is comprised of one or more electronic circuits including semiconductor integrated circuits (ICs) or large scale integrated circuits (LSIs). The integrated circuits such as IC or LSI referred to herein have different names depending on the degree of integration, and include integrated circuits called system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). Furthermore, FPGAs (Field-Programmable Gate Arrays), which are programmed after the LSI is manufactured, or logic devices that can reconfigure the connections inside the LSI or reconfigure the circuit sections inside the LSI, may also be used as processors. I can do it. The plurality of electronic circuits may be integrated into one chip, or may be provided in a distributed manner over a plurality of chips. A plurality of chips may be integrated into one device, or may be distributed and provided in a plurality of devices. The computer system herein includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including semiconductor integrated circuits or large-scale integrated circuits.

(Modified example)
The embodiment is only one of various embodiments of the present disclosure. The embodiments can be modified in various ways depending on the design, etc., as long as the objective of the present disclosure can be achieved.

For example, the shape of the conductive substrate 2 in plan view is not limited to a rectangular shape, but may be any shape, for example, a square shape or a circular shape.

Furthermore, the shapes of the plurality of recesses 45 may be the same. In this case, for example, in the method for manufacturing the electrolysis electrode 1, the plurality of recesses 45 may be formed using etching technology, laser processing technology, or the like. Utilizing these techniques has the advantage of increasing the degree of freedom in designing the layout and size of the plurality of recesses 45, and increasing the reproducibility of the formation positions of the plurality of recesses 45.

Further, in the electrolysis electrode 1, the catalyst layer 4 does not need to be provided with a plurality of recesses 45. In this case, for example, the tantalum oxide layer 5 has a plurality of recesses 45 that expose a part of the main surface 40 of the catalyst layer It is sufficient if it has a hole (for example, a pinhole or a crack).

Further, in the electrolytic electrode 1, even if the catalyst layer 4 is provided with a plurality of recesses 45, or a plurality of cracks are formed in the tantalum oxide layer 5 that expose a part of the catalyst layer 4, good. In the method for manufacturing the electrolytic electrode 1 described above, when the thickness of the tantalum oxide layer 5 is 50 nm or more, cracks that expose a part of the catalyst layer 4 in the tantalum oxide layer 5 occur in the second step of the tantalum oxide layer forming process. may be formed. In addition, in the method for manufacturing the electrolytic electrode 1 described above, cracks are formed in the tantalum oxide layer in the second step of the tantalum oxide layer forming process, and cracks connected to the cracks in the tantalum oxide layer are formed in the catalyst layer 4. Sometimes. The plurality of holes in the tantalum oxide layer 5 may be formed using etching technology, laser processing technology, or the like.

The tantalum oxide layer 5 may contain tantalum in addition to tantalum oxide. In other words, the tantalum oxide layer 5 may be a layer in which tantalum oxide and tantalum are mixed.

Further, the electrolytic electrode 1 has a structure similar to the structure on the second main surface 22 of the conductive substrate 2, which includes the intermediate layer 3, the catalyst layer 4, and the tantalum oxide layer 5 on the first main surface 21 side. Further, it may be provided.

(summary)
Based on the embodiments described above, the following aspects are disclosed in this specification.

The electrolysis electrode (1) according to the first aspect includes a conductive substrate (2), an intermediate layer (3), a catalyst layer (4), and a tantalum oxide layer (5). The conductive substrate (2) has a first main surface (21) and a second main surface (22) opposite to the first main surface (21). The conductive substrate (2) contains at least titanium. The intermediate layer (3) is provided on the first main surface (21) of the conductive substrate (2). The intermediate layer (3) contains platinum. The catalyst layer (4) is provided on the intermediate layer (3). The catalyst layer (4) contains platinum and iridium oxide. A tantalum oxide layer (5) is provided on the catalyst layer (4). In the electrolysis electrode (1), a part of the catalyst layer (4) is exposed. The catalyst layer (4) is a porous layer containing a plurality of composite particles (41) and a plurality of pores (42). Each of the plurality of composite particles (41) includes platinum (platinum particles 411) and iridium oxide (iridium oxide particles 412). The electrolysis electrode (1) further includes a plurality of tantalum oxide parts (43) provided in at least one of the plurality of pores (42) and in contact with the catalyst layer (4). The electrolytic electrode (1) has a structure in which the catalyst layer (4) and a plurality of tantalum oxide parts move closer to the conductive substrate (2) from the main surface (40) of the catalyst layer (4) in the thickness direction of the catalyst layer (4). (43) including a region of increasing concentration of tantalum oxide in a composite layer comprising (43) and (43).

According to the electrolysis electrode (1) according to the first aspect, it is possible to suppress changes in characteristics over time.

In the electrolytic electrode (1) according to the second aspect, in the first aspect, the conductive substrate (2) is formed on the titanium substrate (20) and the titanium substrate (20), and the conductive substrate (2) is formed on the titanium substrate (20). A titanium oxide layer (24) having a titanium oxide layer (24). The first main surface (21) of the conductive substrate (2) includes a surface (241) of the titanium oxide layer (24) on the opposite side to the titanium substrate (20) side. At least one tantalum oxide part (43) among the plurality of tantalum oxide parts (43) penetrates the intermediate layer (3) and is in contact with the titanium oxide layer (24).

According to the electrolysis electrode (1) according to the second aspect, it is possible to improve durability.

In the electrolysis electrode (1) according to the third aspect, in the first or second aspect, the first main surface (21) of the conductive substrate (2) is a rough surface.

In the electrolysis electrode (1) according to the third aspect, it is possible to improve the adhesion between the conductive substrate (2) and the intermediate layer (3). As a result, in the electrolysis electrode (1) according to the third aspect, it is possible to suppress the catalyst layer (4) from peeling off from the conductive substrate (2) side, and it is possible to improve the durability. becomes.

A hypochlorous acid generating device (100) according to a fourth aspect includes a container (110) containing salt water (112), and a first electrode arranged in the container (110) so as to be in contact with the salt water (112). (101A) and a second electrode (101B). At least one of the first electrode (101A) and the second electrode (101B) includes the electrolysis electrode (1) according to any one of the first to third embodiments.

According to the hypochlorous acid generating device (100) according to the fourth aspect, it is possible to suppress changes in characteristics over time.

1 Electrode for electrolysis 2 Conductive substrate 21 First main surface 22 Second main surface 3 Intermediate layer 30 Main surface 4 Catalyst layer 40 Main surface 41 Composite particle 411 Platinum particle 412 Iridium oxide particle 42 Pore 43 Tantalum oxide part 45 Recess 451 Inner surface 5 Tantalum oxide layer 51 First part 52 Second part 100 Hypochlorous acid generator

101A First electrode

101B Second electrode 110 Container 112 Salt water

Claims

a conductive substrate having a first main surface and a second main surface opposite to the first main surface, and containing at least titanium;
an intermediate layer provided on the first main surface of the conductive substrate and containing platinum;
a catalyst layer provided on the intermediate layer and containing platinum and iridium oxide;
An electrode for electrolysis comprising a tantalum oxide layer provided on the catalyst layer,
In the electrolysis electrode, a part of the catalyst layer is exposed,
The catalyst layer is a porous layer including a plurality of composite particles each containing platinum and iridium oxide and a plurality of pores,
The electrolytic electrode is
further comprising a plurality of tantalum oxide parts provided in at least one of the plurality of pores and in contact with the catalyst layer,
In the electrolysis electrode, the concentration of tantalum oxide in the composite layer including the catalyst layer and the plurality of tantalum oxide parts increases as it approaches the conductive substrate from the main surface of the catalyst layer in the thickness direction of the catalyst layer. including the area to
Electrode for electrolysis.
The conductive substrate is
titanium substrate,
a titanium oxide layer formed on the titanium substrate and having conductivity;
The first main surface of the conductive substrate includes a surface of the titanium oxide layer on the opposite side to the titanium substrate side,
At least one tantalum oxide part of the plurality of tantalum oxide parts penetrates the intermediate layer and is in contact with the titanium oxide layer.
The electrode for electrolysis according to claim 1.
the first main surface of the conductive substrate is a rough surface;
The electrode for electrolysis according to claim 1 or 2.
A container that can hold salt water,
comprising a first electrode and a second electrode arranged in the container so as to be in contact with the salt water,
At least one of the first electrode and the second electrode includes the electrolysis electrode according to any one of claims 1 to 3.
Hypochlorous acid generating equipment.