Titanium substrate, electrode for water electrolysis, and solid polymer type water electrolysis device

Abstract

To provide: a titanium base material which enables synthesis of alcohol from carboxylic acid when used as a water electrolysis electrode; and a water electrolysis electrode and a solid polymer type water electrolysis device comprising the titanium base material.SOLUTION: A titanium base material has a base material body 11 made of a sintered body of titanium particles, and a titanium oxide film 16 formed on a surface of the base material body 11. A proportion of anatase-type titanium oxide in titanium oxide constituting the titanium oxide film 16 is 90% or more. Porosity of the base material body 11 is preferably in a range of 30% or more to 92% or less. Compressive strength is preferably 0.5 MPa or more.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a titanium substrate suitable as a water electrolysis electrode for a water electrolysis apparatus used when synthesizing alcohol from carboxylic acid, a water electrolysis electrode made of this titanium substrate, and a solid polymer type water electrolysis apparatus.

Background Art

[0002] Toward realizing a carbon dioxide-free society, renewable energy such as sunlight and wind energy has long been attracting attention as an alternative to fossil energy. However, for the further spread of renewable energy, there are many problems such as (1) an energy transportation method from energy supply areas such as large-scale solar and wind power generation facilities to urban areas which are energy consumption areas, and (2) power loss due to surplus power that cannot be fed into the power grid and the time difference between power demand peaks and supply peaks.

[0003] As one measure to solve these problems, a method of converting electrical energy obtained from surplus renewable energy into chemical energy (compound) using a water electrolysis apparatus and using it as a fossil fuel alternative energy has been studied. Hydrogen and methylcyclohexane are well-known as the above compounds, but in recent years, alcohol, which is more stable and easier to store and transport, has been attracting attention as a next-generation energy source.

[0004] As an example of alcohol synthesis from renewable energy, there is one that applies a solid polymer type water electrolysis apparatus. This water electrolysis apparatus is provided with a titanium electrode having iridium oxide supported as a catalyst on the anode and a titanium electrode having anatase-type titanium oxide supported as a catalyst on the cathode. There is a reported case where glycolic acid was successfully synthesized by reducing oxalic acid on the cathode side using hydrogen generated by water electrolysis at the anode as a raw material (see Non-Patent Document 1). However, in the method of Non-Patent Document 1, the film formation process of anatase-type titanium oxide on the surface of the titanium porous body is complicated and not suitable for mass production.

[0005] Also, as a film-forming process of anatase-type titanium oxide on the surface of a bulk-shaped titanium substrate, anodic oxidation in sulfuric acid of 0.1 M or less is known. Specifically, by maintaining the current density under the condition of 50 mA / cm 2 and applying up to the target voltage of 210 V, film formation of anatase-type titanium oxide film on the surface of a plate-shaped titanium substrate has been successfully achieved (see Non-Patent Document 2).

[0006] Generally, an electrode used for a liquid reaction preferably has a high porosity of 40% or more, and a titanium fiber sintered body is widely used as the above-mentioned electrode. In addition, in the titanium substrate serving as an electrode, when the electrode is incorporated into an electrolytic cell, since high mechanical strength against compression is also important so as to maintain the pore structure, a titanium particle sintered body that is superior in mechanical strength to the titanium fiber sintered body has been proposed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Non-Patent Documents

[0008]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, in the titanium particle sintered body shown in Patent Document 1, due to the manufacturing method, the resistance at the sintering interface of titanium particles becomes high. Therefore, when an anodizing treatment is performed on the titanium particle sintered body at a high voltage exceeding 200 V, heat is generated at the particle sintering interface portion with high resistance, and there is a problem that the porous skeleton burns out. Therefore, it was not possible to obtain a titanium base material having a titanium oxide film made of anatase-type titanium oxide formed on the surface of the titanium particle sintered body.

[0010] The present invention has been made in view of the above circumstances, and aims to provide a titanium base material capable of efficiently synthesizing alcohol from carboxylic acid when used as an electrode for water electrolysis, an electrode for water electrolysis made of this titanium base material, and a solid polymer type water electrolysis device.

Means for Solving the Problems

[0011] In order to solve such problems and achieve the above object, the titanium base material of the present invention has a base material body made of a titanium particle sintered body and a titanium oxide film formed on the surface of this base material body. The base material body includes a skeleton part having a three-dimensional network structure and a pore part surrounded by this skeleton part, and the pore part is structured to communicate with each other and open toward the outside of the base material body. Among the titanium oxides constituting the titanium oxide film, the proportion of anatase-type titanium oxide is 90% or more, the average film thickness of the titanium oxide film is in the range of 0.05 μm or more and 1.0 μm or less, the compressive strength is 0.5 MPa or more, and the specific surface area is 0.1 m 2 / g or more 5.0m 2 / g or less, and the porosity of the base material body is within the range of 30% or more and 92% or less and is characterized by being as described above.

[0012] According to the titanium base material having this configuration, a titanium oxide film is formed on the surface of the base material body made of a titanium particle sintered body, and the proportion of anatase-type titanium oxide among the titanium oxides constituting the titanium oxide film is 90% or more. Therefore, it can be used as an electrode for water electrolysis utilized when synthesizing alcohol from carboxylic acid. Further, since the base material body is composed of a titanium particle sintered body, the porosity is high, and the reaction on the surface of the titanium base material can be promoted. In addition, since the compressive strength is 0.5 MPa or more, even if the base material body is composed of a titanium particle sintered body, it has sufficiently excellent strength and can be stably used as an electrode for water electrolysis. Furthermore, since the specific surface area is 0.1 m 2 / g or more, the surface area of the titanium oxide film having a catalytic action is large, and the reaction on the surface of the titanium base material can be further promoted. Also, since the average film thickness of the titanium oxide film is 0.05 μm or more, the catalytic action of anatase-type titanium oxide can be maintained for a long time. On the other hand, since the average film thickness of the titanium oxide film is 1.0 μm or less, the electric resistance is sufficiently low, and the conductivity of the entire titanium base material can be ensured. Furthermore, since the porosity of the base material body made of the titanium particle sintered body is 30% or more, fluid can be efficiently circulated inside the titanium base material, and the reaction on the surface of the titanium base material can be promoted. On the other hand, since the porosity of the base material body made of the titanium particle sintered body is 92% or less, the strength of the base material body can be ensured.

[0017] The water electrolysis electrode of the present invention is characterized by being composed of the above-described titanium base material. According to the water electrolysis electrode having this configuration, it is composed of a titanium base material in which a titanium oxide film in which the proportion of anatase-type titanium oxide among titanium oxides is 90% or more is formed on the surface of the base material body composed of a titanium particle sintered body. Therefore, due to the catalytic action of the titanium oxide film, it becomes possible to synthesize alcohol from carboxylic acid. In addition, since the base material body is composed of a titanium particle sintered body and has a porous structure, the reaction on the electrode surface can be promoted.

[0018] The solid polymer type water electrolysis device of the present invention is characterized by including the above-described water electrolysis electrode. According to the solid polymer type water electrolysis device having this configuration, it includes a water electrolysis electrode composed of a titanium base material in which a titanium oxide film in which the proportion of anatase-type titanium oxide among titanium oxides is 90% or more is formed on the surface of the base material body composed of a titanium particle sintered body. Therefore, due to the catalytic action of the titanium oxide film, it becomes possible to synthesize alcohol from carboxylic acid. In addition, since the base material body is composed of a titanium particle sintered body and has a porous structure, the reaction on the electrode surface can be promoted.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide a titanium base material capable of efficiently synthesizing alcohol from carboxylic acid when used as an electrode for water electrolysis, an electrode for water electrolysis made of this titanium base material, and a solid polymer type water electrolysis device.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0021] Hereinafter, a titanium base material, an electrode for water electrolysis, and a solid polymer type water electrolysis device which are embodiments of the present invention will be described with reference to the attached drawings.

[0022] The titanium base material 10 of the present embodiment is, for example, used as a cathode electrode of a solid polymer type water electrolysis device for synthesizing alcohol from carboxylic acid.

[0023] As shown in FIGS. 1 and 2, the titanium base material 10 of the present embodiment has a base material body 11 made of a titanium particle sintered body and a titanium oxide film 16 formed on the surface of the base material body 11. And in the present embodiment, as shown in FIG. 3, the proportion of anatase-type titanium oxide among the titanium oxides constituting the titanium oxide film 16 is 90% or more. In this anatase-type titanium oxide, it acts as a catalyst when reducing carboxylic acid to synthesize alcohol. Note that the proportion of anatase-type titanium oxide among the titanium oxides constituting the titanium oxide film 16 is preferably 91% or more, and more preferably 92% or more.

[0024] In the present embodiment, as shown in FIG. 1, the base material body 11 made of a titanium particle sintered body is a porous body, and includes a skeleton portion 12 having a three-dimensional network structure and a pore portion 13 surrounded by the skeleton portion 12. Further, the pore portions 13 surrounded by the skeleton portion 12 communicate with each other and have a structure opening toward the outside of the base material body 11. It is preferable that the porosity P of the base material body 11 is in the range of 30% or more and 92% or less. The porosity P of the base material body 11 is calculated by the following formula. P(%)=(1-(W / (V×D T )))×100 W: Mass (g) of the base material body 11 V: Volume (cm 3 ) of the base material body 11 D T : True density (g / cm 3 ) of titanium

[0025] By setting the porosity P of the base material body 11 made of a titanium particle sintered body to 30% or more, liquids, gases, etc. can flow well inside the titanium base material 10, and the reaction in the titanium base material 10 can be promoted. On the other hand, by setting the porosity P of the base material body 11 made of a titanium particle sintered body to 92% or less, the strength of the titanium base material 10 can be ensured. Here, in order to further promote the reaction in the titanium substrate 10, it is more preferable that the porosity P of the substrate main body 11 is 40% or more, and more preferably 50% or more. Further, in order to further improve the strength of the titanium substrate 10, it is more preferable that the porosity P of the substrate main body 11 is 90% or less, and more preferably 88% or less.

[0026] Also, in the present embodiment, it is preferable that the specific surface area of the titanium substrate 10 is 0.1 m 2 / g or more. When the specific surface area of the titanium substrate 10 is 0.1 m 2 / g or more, the surface area of the titanium oxide film 16 formed on the surface of the substrate main body 11 is large, and the catalytic action of anatase-type titanium oxide can be sufficiently exerted, making it possible to further promote the reaction. Here, in order to further exert the catalytic action of anatase-type titanium oxide, it is more preferable that the specific surface area of the titanium substrate 10 is 0.2 m 2 / g or more, and more preferably 0.3 m 2 / g or more. Although there is no particular limitation on the upper limit of the specific surface area of the titanium substrate 10, it is preferably substantially 5.0 m 2 / g or less.

[0027] Furthermore, in the present embodiment, it is preferable that the average film thickness t of the titanium oxide film 16 is in the range of 0.05 μm or more and 1.0 μm or less. When the average film thickness t of the titanium oxide film 16 is 0.05 μm or more, the catalytic action of anatase-type titanium oxide can be maintained for a long time. On the other hand, when the average film thickness t of the titanium oxide film 16 is 1.0 μm or less, the electrical resistance becomes sufficiently low, ensuring the conductivity of the entire titanium substrate 10. Here, in order to maintain the catalytic action of the anatase-type titanium oxide for an even longer time, it is more preferable that the average film thickness t of the titanium oxide film 16 be 0.07 μm or more, and even more preferably 0.1 μm or more. Further, in order to further ensure the conductivity of the entire titanium substrate 10, it is more preferable that the average film thickness t of the titanium oxide film 16 be 0.9 μm or less, and even more preferably 0.8 μm or less.

[0028] Also, in the present embodiment, it is preferable that the compressive strength of the titanium substrate 10 be 0.5 MPa or more. When the compressive strength of the titanium substrate 10 is 0.5 MPa or more, sufficient strength is ensured, deformation and cracking during use can be suppressed, and it can be stably used as an electrode. Here, in order to further suppress deformation and cracking during use, it is more preferable that the compressive strength of the titanium substrate 10 be 0.7 MPa or more, and even more preferably 0.9 MPa or more.

[0029] Next, a method for manufacturing the titanium substrate 10 according to the present embodiment will be described with reference to the flowchart of FIG. 4.

[0030] (Substrate body preparation step S01) First, a titanium particle sintered body to be the substrate body 11 is prepared. This titanium particle sintered body can be manufactured, for example, by the following steps. A sintering raw material containing titanium is mixed with an organic binder, a foaming agent, a plasticizer, water, and, if necessary, a surfactant to prepare a foaming slurry. This foaming slurry is applied using a doctor blade (coating device) to form a sheet-shaped molded body. This sheet-shaped molded body is heated and foamed to obtain a foamed molded body. Then, after degreasing this, it is sintered. Thereby, a titanium particle sintered body is produced. (See, for example, JP-A-2006-138005 and JP-A-2003-082405.)

[0031] (Annealing treatment step S02) Next, an annealing treatment is performed on the titanium particle sintered body obtained as described above. Specifically, the above-mentioned titanium particle sintered body is placed on a setter made of zirconia, and the annealing treatment is performed under the conditions of a vacuum degree of 1 Pa or less, a holding temperature of 1200°C or higher and 1300°C or lower, and a holding time of 0.5 hours or longer and 3.0 hours or shorter. By this annealing treatment step S02, it becomes possible to lower the resistance at the particle sintering interface portion. As a result, in the anodization step S03 described later, heat generation at the particle sintering interface portion can be suppressed, and the strength of the titanium base material 10 can be improved.

[0032] (Anodization step S03) Next, an anodic oxidation is performed on the titanium particle sintered body (base material main body 11) that has been subjected to the annealing treatment to form a titanium oxide film 16. In the present embodiment, a titanium oxide film 16 in which the proportion of anatase-type titanium oxide is 90% or more is formed by performing anodic oxidation in sulfuric acid with a sulfuric acid concentration of 0.2 M or less at a voltage of 200 V or less.

[0033] By the above manufacturing method, it becomes possible to manufacture a titanium base material 10 in which a titanium oxide film 16 in which the proportion of anatase-type titanium oxide is 90% or more is formed on the surface of the base material main body 11 made of a titanium particle sintered body.

[0034] Next, a schematic diagram of the water electrolysis electrode and the water electrolysis device according to the present embodiment is shown in FIG. 5. The water electrolysis device of the present embodiment is a solid polymer type water electrolysis device.

[0035] As shown in FIG. 5, the solid polymer type water electrolysis device 30 of the present embodiment includes a water electrolysis cell 31 including an anode electrode 32 and a cathode electrode 33 arranged opposite to each other, and an ion permeable membrane 34 arranged between the anode electrode 32 and the cathode electrode 33. A catalyst layer 35 is formed on the contact surface of the ion permeable membrane 34 with the anode electrode 32. Here, for the anode electrode 32, the ion permeable membrane 34, and the catalyst layer 35, those used in conventional general polymer electrolyte type water electrolysis devices can be applied.

[0036] And the above-described cathode electrode 33 is the water electrolysis electrode of the present embodiment. This cathode electrode 33 (water electrolysis electrode) is composed of the titanium base material 10 of the present embodiment described above, and has a structure in which a titanium oxide film 16 in which the proportion of anatase type titanium oxide occupies 90% or more is formed on the surface of the base material body 11 made of a titanium particle sintered body.

[0037] In the above-described polymer electrolyte type water electrolysis device 30, as shown in FIG. 5, water (H2O) is supplied from the anode electrode 32 side, an aqueous carboxylic acid solution is supplied to the cathode side, and the anode electrode 32 and the cathode electrode 33 are energized. Then, oxygen (O2) generated by the electrolysis of water is discharged from the anode electrode 32, and hydrogen ions generated at the anode electrode permeate the ion exchange membrane 34 and move to the cathode electrode. Using this hydrogen as a raw material, alcohol is synthesized by reducing carboxylic acid on the cathode electrode 33 side. At this time, the titanium oxide film 16 (the proportion of anatase type titanium oxide in the titanium oxide is 90% or more) formed on the surface of the cathode electrode 33 serves as a catalyst, and the reduction reaction of carboxylic acid is promoted. The reduced alcohol is discharged from the cathode electrode 33.

[0038] According to the titanium base material 10 of the present embodiment configured as described above, a titanium oxide film 16 is formed on the surface of the base material body 11 made of a titanium particle sintered body, and the proportion of anatase type titanium oxide in the titanium oxide constituting the titanium oxide film 16 is 90% or more. Therefore, when synthesizing alcohol from carboxylic acid using a polymer electrolyte type water electrolysis device, it can be used as the water electrolysis electrode (cathode electrode) of the polymer electrolyte type water electrolysis device. Further, since the base material body 11 is composed of a titanium particle sintered body, the porosity is high, and the reduction reaction of carboxylic acid in the water electrolysis electrode (cathode electrode) can be promoted.

[0039] In the present embodiment, when the porosity of the base material body 11 is within the range of 30% or more and 92% or less, the reaction on the surface of the titanium base material 10 can be promoted, the strength of the base material body 11 can be ensured, and it can be suitably used as an electrode.

[0040] In the present embodiment, when the compressive strength of the titanium base material 10 is 0.5 MPa or more, even if the base material body 11 is composed of a porous sintered body of titanium particles, it is sufficiently excellent in strength, can suppress the occurrence of deformation and cracking during use, and can be stably used as the cathode electrode 33.

[0041] In the present embodiment, when the specific surface area of the titanium base material 10 is 0.1 m 2 / g or more, the surface area of the titanium oxide film 16 having a catalytic action is large, and the reaction on the surface of the titanium base material 10 can be further promoted.

[0042] In the present embodiment, when the average film thickness t of the titanium oxide film 16 is within the range of 0.05 μm or more and 1.00 μm or less, the catalytic action of anatase-type titanium oxide can be maintained for a long time, the electrical resistance is sufficiently low, and the conductivity of the entire titanium base material 10 can be ensured. Therefore, it can be stably used as an electrode.

[0043] In the electrode for water electrolysis (cathode electrode 33) according to the present embodiment and the solid polymer type water electrolysis apparatus 30 according to the present embodiment including this cathode electrode 33, since it is composed of the above-described titanium base material 10, alcohol synthesis from carboxylic acid becomes possible due to the catalytic action of the titanium oxide film 16. Further, since the base material body 11 is composed of a sintered body of titanium particles and has a porous structure, the reaction on the surface of the cathode electrode 33 can be promoted.

[0044] As described above, the embodiments of the present invention have been described, but the present invention is not limited thereto, and can be appropriately changed without departing from the technical idea of the invention. For example, in the present embodiment, a solid polymer type water electrolysis device (water electrolysis cell) having the structure shown in FIG. 5 was described as an example, but the present invention is not limited thereto. Any water electrolysis device (water electrolysis cell) having a different structure may be used as long as it includes the water electrolysis electrode made of the titanium base material according to the present embodiment.

Example

[0045] The results of the confirmation experiments conducted to confirm the effects of the present invention will be described below. First, the base material bodies shown in Table 1 were prepared. The dimensions of the prepared base material bodies were 25 mm in width and 25 mm in length, and the average film thickness was as described in Table 1. In Examples 1-6 and Comparative Examples 1 and 2 of the present invention, a sintered body of titanium particles was used, and in Comparative Example 3, a sintered body of titanium fibers was used. Here, the pore diameter and porosity of the base material body were measured as follows. Note that the sintered body of titanium fibers is a member that uses titanium fibers (diameter: 20 μm or more and 50 μm or less) as a raw material and is made porous through a sintering process.

[0046] (Pore diameter) Using an optical camera LEICA DMS300 manufactured by Leica, various titanium members were photographed. The photographed images were binarized with respect to the electrode skeleton portion and the pore portion using image analysis software Win ROOF manufactured by Mitani Shosha Co., Ltd., and the pore diameter was calculated.

[0047] (Porosity) The porosity was calculated by the following formula: P(%)=(1-(W / (V×D T )))×100 W: Mass (g) V: Volume (cm 3 ) D T : True density of titanium (g / cm 3 ) Note that for calculating the volume V of the base material body 11, the thickness of the base material body 11 measured with a digital micrometer and the longitudinal and lateral lengths measured with a digital caliper were used. Also, the mass of the base material body 11 was measured with an electronic balance.

[0048] Next, in Examples 1-6 and Comparative Example 1 of the present invention, annealing treatment was carried out under a vacuum of 1 Pa or less, a holding temperature of 1250 ° C, and a holding time of 10 hours. In Comparative Examples 2 and 3, annealing treatment was not carried out. Next, anodization was performed on the surface of the base material body by the methods and conditions shown in Table 1 to form a titanium oxide film.

[0049] In this way, a titanium substrate with a titanium oxide film formed on the surface of the base material body was obtained. For the obtained titanium substrate, the identification, compressive strength, and specific surface area of the titanium oxide film were evaluated as follows.

[0050] (Identification of titanium oxides in the titanium oxide film) Using a Rigaku fully automatic multi-purpose X-ray diffractometer (product name: SmartLab), the titanium oxides in the titanium oxide film were identified by X-ray diffraction analysis (XRD) method, and the ratio (R a ) of anatase-type titanium oxide and the ratio (R r ) of rutile-type titanium oxide were evaluated. The X-ray source used was a Cu tube target (CuKα ray), and the measurement angle range was 15 - 90°. For the calculation of the above ratios, the peak intensity at 25.3° of anatase-type titanium oxide was taken as I a , and the peak intensity at 27.4° of rutile-type titanium oxide was taken as I r , and the following formula was used. R a =I a / (I a +I r ) R r =I r / (I a +I r ) I a : Total number of X-ray detections in the range of 24.3 - 26.3° after removing the background I r : Total number of X-ray detections in the range of 26.4 - 28.4° after removing the background

[0051] (Average film thickness of the titanium oxide film) The sample after film formation was resin-embedded and cut perpendicular to the thickness direction of the titanium oxide film to expose the cross-section. This cross-section was observed by SEM, and five points were evenly taken from end to end of the titanium oxide film layer shown in the SEM image observed at a magnification of 20,000 times, and the average film thickness was calculated for each. Then, the average film thickness of the titanium oxide film was determined from the average value of the five measured points. The evaluation results are shown in Table 1.

[0052] (Compressive strength) A compression test was carried out to evaluate the compressive strength. The evaluation results are shown in Table 1.

[0053] (Specific surface area of the substrate body) The sample after film formation was cut into square pieces of 2 mm × 2 mm or less, and about 0.3 g was filled into a sample folder. The sample folder was placed on an AUTOSORB-iQ2 manufactured by QUANTACHROME and degassed at 200 degrees for 60 minutes. Then, krypton gas was introduced and the specific surface area was measured. The evaluation results are shown in Table 1.

[0054]

Table 1

[0055] In Comparative Example 1, anodic oxidation was carried out in sulfuric acid with a sulfuric acid concentration of 0.4 M. In the formed titanium oxide film, the proportion of anatase-type titanium oxide was less than 90%. Therefore, the titanium oxide film could not be used as a catalyst for the reduction reaction of carboxylic acid.

[0056] In Comparative Example 2, the substrate body made of a titanium particle sintered body was not subjected to annealing treatment, and anodic oxidation was carried out in sulfuric acid with a sulfuric acid concentration of 0.1 M. Cracks occurred in the substrate body during anodic oxidation, so the subsequent evaluation was aborted. It is presumed that heat was generated at the particle sintering interface with high resistance during anodic oxidation, and the porous skeleton was burned out.

[0057] In Comparative Example 3, an annealing treatment was not performed on the substrate body made of the titanium fiber sintered body, and anodic oxidation was performed under the condition that the sulfuric acid concentration was 0.1 M. The compressive strength was 0.1 MPa or less, which was below the measurement lower limit value, indicating insufficient strength.

[0058] On the other hand, in Examples 1-6 of the present invention, an annealing treatment was performed on the substrate body made of the titanium particle sintered body, and anodic oxidation was performed in sulfuric acid with a sulfuric acid concentration of 0.2 M or less. In the formed titanium oxide film, the proportion of anatase-type titanium oxide was 90% or more, and it was possible to be used as a catalyst for the reduction reaction of carboxylic acid. In addition, the compressive strength was sufficiently high, the specific surface area was large, and it could be stably used as an electrode.

[0059] From the results of the above confirmation experiments, it was confirmed that according to the examples of the present invention, it was possible to provide a titanium substrate that enables the synthesis of alcohol from carboxylic acid when used as an electrode for water electrolysis.

Explanation of Reference Numerals

[0060] 10 Titanium substrate 11 Substrate body 16 Titanium oxide film 30 Solid polymer type water electrolysis device 33 Cathode electrode (electrode for water electrolysis)

Claims

1. It has a base material body made of a titanium particle sintered body and a titanium oxide film formed on the surface of this base material body, The base material body includes a skeleton part having a three-dimensional network structure and a pore part surrounded by this skeleton part, and the pore part has a structure in which they communicate with each other and open toward the outside of the base material body, The proportion of anatase-type titanium oxide among the titanium oxides constituting the titanium oxide film is 90% or more, The average film thickness of the titanium oxide film is in the range of 0.05 μm or more and 1.0 μm or less, The compressive strength is 0.5 MPa or more, and the specific surface area is 0.1 m ２ / g or more and 5.0 m2 / g or less, and A titanium base material characterized in that the porosity of the base material body is in the range of 30% or more and 92% or less.

2. An electrode for water electrolysis, characterized in that it is made of the titanium base material according to Claim 1.

3. A solid polymer type water electrolysis device, characterized in that it includes the electrode for water electrolysis according to Claim 2.

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