Structure for electrochemical reactions, electrode for electrochemical reactions, cell for electrochemical reactions, sensor for electrochemical measurement, and method for manufacturing an electrode for electrochemical reactions.

Abstract

This invention provides a technology that allows a sealing member to be placed without contacting the electrode film made of polycrystalline diamond. [Solution] The device comprises a conductive substrate, a chip-shaped or plate-shaped electrode having an electrode film made of boron-doped polycrystalline diamond on one of the two main surfaces of the substrate, and a sealing member, wherein the substrate has a protrusion on the surface having the electrode film, the electrode film is provided at least on the top surface of the protrusion, and the sealing member is arranged to surround the periphery of the protrusion.

Description

[Technical Field]

[0001] This disclosure relates to an electrochemical reaction structure, an electrochemical reaction electrode, an electrochemical reaction cell, an electrochemical measurement sensor, and a method for manufacturing an electrochemical reaction electrode. [Background technology]

[0002] Conventionally, electrodes equipped with an electrode film made of boron-doped polycrystalline diamond (BDD (Boron Doped Diamond) film) and electrochemical measuring devices equipped with such BDD electrodes have been proposed as electrodes for electrochemical reactions. For example, a dissolved ozone concentration measuring device has been proposed that includes a BDD electrode as a working electrode, a counter electrode, a reference electrode, an electrolytic cell which is a hollow box-shaped member configured to hold a sample solution inside, and a control detection unit connected to the BDD electrode, counter electrode, and reference electrode by conductive wires, with the BDD electrode positioned on the bottom surface of the electrolytic cell so that the surface on which the electrode film is formed faces upward (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2007-212232 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, in the dissolved ozone concentration measuring device described above, for example, in order to measure only the reaction current generated at the wetted surface of the BDD membrane having a predetermined area, it is necessary to prevent the test liquid from coming into contact with areas of the BDD electrode other than the part of the BDD electrode that can contribute to the electrochemical reaction (the wetted part of the BDD electrode), i.e., areas other than the wetted surface of the BDD membrane (hereinafter also simply referred to as the "wetted surface"). The wetted surface of the BDD membrane refers to the area of ​​the BDD membrane that can come into contact with the test liquid. In conventional technology, for example, as shown in Figure 12, a sealing member 30 such as an O-ring is pressed against the surface of the BDD membrane 102 to prevent the test liquid from coming into contact with areas of the BDD electrode 400 other than the wetted surface. As a result, the surface of the BDD membrane 102 may become contaminated by the sealing member 30, which can reduce sensitivity. In addition, the surface of the BDD membrane 102 is a sharp, uneven surface. Therefore, pressing the sealing member 30 against the surface of the BDD membrane 102 caused scratches on the surface of the sealing member, resulting in the test fluid coming into contact with areas other than the wetted surface.

[0005] Furthermore, in the above method, the surface of the BDD film 102 exposed from the inner region of the sealing member 30, such as an O-ring, becomes the wetted surface. Therefore, the wetted area of ​​the BDD film 102 is determined by the sealing member 30. For this reason, the wetted area may change depending on the degree of deformation of the sealing member 30 (the degree to which the sealing member 30 is pressed). Note that "wetted area" refers to the area of ​​the wetted surface of the BDD film 102 when the BDD electrode 400 is viewed from above in a direction perpendicular to the main surface of the BDD film 102.

[0006] The purpose of this disclosure is to provide a technology that enables the placement of a sealing member without contact with an electrode film made of polycrystalline diamond. [Means for solving the problem]

[0007] According to one aspect of this disclosure, A conductive substrate, and a chip-shaped or plate-shaped electrode having an electrode film made of boron-doped polycrystalline diamond on one of the two main surfaces of the substrate, sealing member and comprising, the substrate has convex portions on the surface having the electrode film, the electrode film is provided at least on the top surfaces of the convex portions, the sealing member is arranged so as to surround the periphery of the convex portions, a structure for an electrochemical reaction is provided.

[0008] According to another aspect of the present disclosure, a flat plate-shaped substrate having conductivity, an electrode film made of boron-doped diamond polycrystal on one of the two main surfaces of the substrate, are provided, the substrate has convex portions on the surface having the electrode film, the electrode film is provided at least on the top surfaces of the convex portions, a chip-shaped or plate-shaped electrode for an electrochemical reaction is provided.

[0009] According to still another aspect of the present disclosure, a step of preparing a conductive substrate, a step of performing a seeding treatment or a scratch treatment on either one of the two main surfaces of the substrate, a step of performing grinding on the surface of the substrate on which the seeding treatment or the scratch treatment has been performed to cut out convex portions from the surface, or a step of performing groove formation processing on the surface to form grooves on the surface, a step of forming an electrode film made of boron-doped diamond polycrystal on the surface of the substrate on which the seeding treatment or the scratch treatment has been performed, a step of cutting the substrate on which the electrode film has been formed into a predetermined chip shape or plate shape, A method for manufacturing an electrode for an electrochemical reaction is provided.

Advantages of the Invention

[0010] According to the present disclosure, a technique capable of arranging a sealing member without contacting an electrode film made of diamond polycrystal can be provided.

Brief Description of the Drawings

[0011] [Figure 1] (a) shows a schematic configuration top view of an example of a structure for an electrochemical reaction according to an aspect of the present disclosure, and (b) shows a cross-sectional view taken along the line A-A' of FIG. 1(a). [Figure 2] (a) shows a schematic configuration top view of an example of an electrode for an electrochemical reaction according to an aspect of the present disclosure, and (b) shows a cross-sectional view taken along the line B-B' of FIG. 2(a). [Figure 3] It is a SEM image of an electrode film included in an electrode for an electrochemical reaction according to an aspect of the present disclosure, taken from directly above in the vertical direction, and (b) is a SEM image of a longitudinal cross-section of the electrode. [Figure 4] It is a diagram showing an example of a schematic configuration of an electrochemical cell in which a structure for an electrochemical reaction according to an aspect of the present disclosure can be suitably applied as an electrode of an electrochemical measurement sensor. [Figure 5] (a) shows a schematic configuration top view of an example of an electrochemical measurement sensor using a structure for an electrochemical reaction according to an aspect of the present disclosure as an electrode, (b) shows a cross-sectional view taken along the line C-C' of FIG. 5(a), (c) shows a schematic configuration top view of another example of an electrochemical measurement sensor using a structure for an electrochemical reaction according to an aspect of the present disclosure as an electrode, and (d) shows a cross-sectional view taken along the line D-D' of FIG. 5(c). [Figure 6] It is a schematic diagram of a vapor phase growth apparatus used when growing polycrystalline diamond. [Figure 7] (a) shows an example of a top view of a laminated substrate according to an aspect of the present disclosure, and (b) shows a cross-sectional view taken along the line E-E' of FIG. 7(a). [Figure 8] (a) shows a schematic configuration top view of an example of an electrode for an electrochemical reaction according to a modification of an aspect of the present disclosure, and (b) shows a cross-sectional view taken along the line F-F' of FIG. 8(a). [Figure 9] (a) shows an example of a top view of a laminated substrate according to a modification of an aspect of the present disclosure, and (b) shows a cross-sectional view taken along the line G-G' of FIG. 9(b). [Figure 10] It is a diagram showing a schematic configuration of an example of a structure for an electrochemical reaction according to a modification of an aspect of the present disclosure in a longitudinal cross-section. [Figure 11] (a) is an example of a schematic diagram showing how an electrochemical reaction structure according to a modified embodiment of the present disclosure is attached to piping configured for the flow of the test liquid, and (b) is an example of a schematic diagram showing how an electrochemical reaction structure according to a modified embodiment of the present disclosure is attached to a housing configured to hold the test liquid inside. [Figure 12] This is a schematic diagram showing the installation state of a conventional sealing member. [Modes for carrying out the invention]

[0012] <One aspect of this disclosure> (1) Structure of the electrochemical reaction system The electrochemical reaction structure 10 (hereinafter also referred to as structure 10) according to this embodiment will be described in detail below with reference to Figures 1 to 5.

[0013] As shown in Figures 1(a) and 1(b), the electrochemical reaction structure 10 according to this embodiment comprises an electrode 100, a support 20 that supports the electrode 100, a sealing member 30, and a member 40 that covers the electrode 100.

[0014] As shown in Figures 2(a) and 2(b), the electrode 100 is composed of a substrate 101 and an electrode film 102.

[0015] A conductive, flat substrate is used as the substrate 101. Specifically, the substrate 101 can be a flat substrate composed mainly of silicon (Si) and containing a p-type dopant such as boron (B) at a predetermined concentration, for example, a flat, p-type single-crystal Si substrate. The substrate 101 may also be a flat, p-type polycrystalline Si substrate. The B concentration in the substrate 101 is, for example, 1 × 10⁻⁶. 16 cm -3 The above 2 x 10 20 cm -3 The following is true: By keeping the B concentration in substrate 101 within the above range, it is possible to lower the resistivity of substrate 101 while avoiding a decrease in manufacturing yield and performance degradation of substrate 101.

[0016] The thickness of the substrate 101 (at its thickest point) is, for example, 500 μm or more. A substrate 101 of this thickness can be obtained by cutting a substrate from a single-crystal Si ingot with a diameter of 6 inches or 8 inches, and then polishing and cleaning both sides to a mirror finish. There is no particular upper limit to the thickness of the substrate 101, but it can be, for example, around 2000 μm in accordance with the specifications of the sealing member 30 that is expected to be used.

[0017] The substrate 101 may be a substrate other than a substrate composed primarily of Si (Si substrate). For example, the substrate 101 may be a substrate composed of a Si compound such as a silicon carbide substrate (SiC substrate).

[0018] Furthermore, the substrate 101 may be a metal substrate composed mainly of niobium (Nb), molybdenum (Mo), titanium (Ti), etc. However, when a metal substrate is used, leakage current is likely to occur from the sides of the protrusions 101c described later. For this reason, it is preferable that the substrate 101 be a substrate composed of a Si substrate or a Si compound.

[0019] One of the two main surfaces of the substrate 101 (hereinafter also referred to as the "upper surface of the substrate 101") is provided with an (island-shaped) protrusion 101c on which the sealing member 30 described later can be placed along the outer peripheral surface (see Figure 2(b)).

[0020] The protrusion 101c can be machined out onto the upper surface of the substrate 101 by performing a predetermined grinding process on the upper surface of the substrate 101. The protrusion 101c is, for example, cylindrical. That is, the planar shape of the protrusion 101c (the shape of the protrusion 101c in a plan view when viewed from above perpendicular to the main surface of the substrate 101) is, for example, circular. Alternatively, the protrusion 101c may be, for example, prismatic. That is, the planar shape of the protrusion 101c may be, for example, rectangular or square.

[0021] The diameter d1 and height h1 of the protrusion 101c in plan view can be set to sizes corresponding to the sealing member 30 described later. If, for example, an O-ring is used as the sealing member 30, the diameter d1 and height h1 of the protrusion 101c can be set to sizes corresponding to the O-ring standard (for example, the SS standard or M standard for O-rings). An example of the size of the protrusion 101c (diameter d1 and height h1 of the protrusion 101c) is shown in Table 1 below.

[0022] [Table 1]

[0023] As shown in Figures 2(a) and 2(b), an electrode film 102 is provided on the upper surface of the substrate 101, specifically on the top surface of the protrusion 101c provided on the substrate 101. The electrode film 102 is composed of boron (B)-doped polycrystalline diamond (BDD polycrystalline). That is, the electrode film 102 is a conductive BDD polycrystalline film. The electrode film 102 can be grown (deposited, synthesized) by chemical vapor deposition (CVD) or physical vapor deposition (PVD). Examples of CVD methods include hot filament CVD using tungsten filaments and plasma CVD, while examples of PVD methods include ion beam CVD and ionization evaporation. The thickness of the electrode film 102 is, for example, 0.5 μm to 50 μm, preferably 10 μm to 20 μm. The surface of the electrode film 102, which is made of BDD polycrystalline material, has sharp irregularities, as shown in Figures 3(a) and 3(b).

[0024] The B concentration in the electrode film 102 is, for example, 1 × 10⁻⁶ 19 cm -3 The above 1 x 10 22 cm -3The following applies: The concentration of B in the electrode film 102 can be measured, for example, by secondary ion mass spectrometry (SIMS). SIMS is a method for measuring the concentration of a predetermined substance by detecting ions (secondary ions) generated when a beam of ions (primary ions) is irradiated onto the surface of the electrode film 102 using a mass spectrometer.

[0025] Thus, the electrode 100 is an electrode (BDD electrode) equipped with an electrode film 102 composed of BDD polycrystalline material. Because BDD electrodes are chemically very stable, they can be suitably used even when the test solution is a strongly oxidizing solution. For example, BDD electrodes are suitably used for electrochemical measurements of dissolved ozone concentration and dissolved chlorine concentration. In addition, BDD electrodes have a wider potential window compared to electrodes composed of materials other than BDD (hereinafter also referred to as "other electrodes"). For this reason, a higher voltage can be applied to the BDD electrode during measurement than to other electrodes, or a large current with a reverse bias can be passed through it when cleaning the surface of the electrode film 102, for example. Thus, BDD electrodes can be suitably used even in harsher environments and conditions than other electrodes.

[0026] As shown in Figures 2(a) and 2(b), the electrode 100 has a conductive thin film 103 on the other side of the substrate 101 that is different from one of the two main surfaces of the substrate 101 (the top surface of the substrate 101) (hereinafter also referred to as the "back surface of the substrate 101"). This ensures reliable electrical connection between the electrode 100 and the conductor portion 21 of the support 20 described later. Examples of constituent materials for the conductive thin film 103 include various precious metals such as copper (Cu), gold (Au), platinum (Pt), silver (Ag), and palladium (Pd), various metals such as aluminum (Al), iron (Fe), nickel (Ni), chromium (Cr), and titanium (Ti), alloys mainly composed of these precious metals or metals, oxides of the above precious metals or alloys, metal oxides, and carbon. The conductive thin film 103 can be provided by vapor deposition, subtractive deposition, semi-additive deposition, screen printing, gravure printing, offset printing, inkjet printing, and other printing methods.

[0027] The electrode 100 is configured as a vertical electrode including a conductive substrate 101, an electrode film 102, and a conductive thin film 103. The vertical electrode is an electrode configured to extract a current caused by an electrochemical reaction generated on the surface of the electrode film 102 from the back side of the substrate 101.

[0028] The electrode 100 is formed in a chip shape. The outer shape (planar shape) of the chip-shaped electrode 100 is, for example, rectangular or square. From the viewpoint of reliably preventing the occurrence of liquid leakage described later by the seal member 30, the electrode 100 preferably has a size (planar area) with a margin with respect to the size of the seal member 30 described later. For example, the planar area of the electrode 100 is 4 mm 2 or more, and thereby, the electrode 100 can be made to have a size with a margin with respect to the size of the seal member 30. Also, when the planar area of the electrode 100 is, for example, 4 mm 2 or more, a decrease in the handling property and a decrease in the mounting stability of the electrode 100 are also suppressed. Also, the planar area of the electrode 100 is preferably 25 mm 2 or more, and thereby, the size of the electrode 100 can be surely made to have a size with a margin with respect to the size of the seal member 30. Here, the "size with a margin with respect to the size of the seal member 30" means, for example, when the electrode 100 is viewed from directly above in a direction perpendicular to the main surface of the electrode film 102 in a state where the seal member 30 is arranged as described later, the shortest width of the region of the electrode 100 located outside the seal member 30 (hereinafter, also referred to as the "shortest width of the outer region of the electrode 100") is 0.5 times or more the wire diameter (width) of the seal member 30. Also, the planar area of the electrode 100 is, for example, 200 mm 2 or less, which is preferable, and thereby, an increase in the size of the electrode 100, and thus, the structure 10 including the electrode 100 is avoided. Also, it is more preferable that the planar area of the electrode 100 is 100 mm 2 or less, and thereby, an increase in the size of the electrode 100, and thus, the structure 10 including the electrode 100 is surely avoided. Note that the planar shape and the planar area of the electrode 100 are the shape and the area of the electrode 100, respectively, when the electrode 100 is viewed from directly above in a direction perpendicular to the main surface of the substrate 101.

[0029] The support 20 is configured to support (mount) the electrode 100 on one of its two main surfaces. The support 20 can be made of an insulating material such as an insulating composite resin, ceramic, glass, or plastic. Preferably, the support 20 is made of an engineering plastic such as polyetheretherketone (PEEK) resin or polyethylene terephthalate (PET). Alternatively, the support 20 may be a semiconductor substrate or a metal substrate configured such that the surface on which the electrode 100 is provided is insulating.

[0030] As shown in Figure 1(b), the support 20 includes a conductor portion 21. Examples of materials used for the conductor portion 21 include those similar to those used for the conductive thin film 103 described above. Furthermore, the conductor portion 21 can be provided on the support 20 using the same method as for the conductive thin film 103.

[0031] The support 20 supports the electrode 100 such that the conductive thin film 103 is in contact with the conductor portion 21. The electrode 100 is also detachably supported on the support 20. In other words, in the structure 10, the electrode 100 is supported on the support 20 without bonding the conductive thin film 103 and the conductor portion 21 with a conductive adhesive or the like, and without covering the electrical connection point 50 (hereinafter also referred to as "connection point 50") between the conductive thin film 103 and the conductor portion 21 with an insulating resin or the like.

[0032] If the surface of the electrode film 102 becomes contaminated due to an electrochemical reaction, the sensitivity of the electrode 100 may decrease. Also, because the electrode 100 is a vertical electrode, if the substrate 101 comes into contact with the test solution and the substrate 101 corrodes, the sensitivity of the electrode 100 may also decrease. For this reason, the electrode 100 is a consumable item that requires periodic replacement. If the electrode 100 is supported on the support 20 using a conductive adhesive or by covering the connection point 50 with an insulating resin, it is difficult to replace only the electrode 100, and the entire structure 10 containing the electrode 100 must be replaced. In contrast, in the structure 10 according to this embodiment, the electrode 100 is detachably supported on the support 20. This makes it possible to replace only the electrode 100.

[0033] The sealing member 30 is arranged to surround the entire circumference of the protrusion 101c provided on the substrate 101. For example, an O-ring can be used as the sealing member 30. Alternatively, an oil seal packing, gasket, liquid sealing material (such as silicone sealant (product name)) can also be used as the sealing member 30.

[0034] As the sealing member 30 is arranged as described above, the planar shape and wetted area of ​​the wetted surface of the electrode film 102 are determined by the planar shape and flat area of ​​the protrusion 101c. Therefore, by keeping the planar shape and flat area of ​​the protrusion 101c constant among multiple electrodes 100, the planar shape and wetted area of ​​the wetted surface of the electrode film 102 can be kept constant. In this way, since the planar shape and wetted area of ​​the wetted surface of the electrode film 102 are determined independently of the sealing member 30, variations in the wetted area among multiple electrodes 100 when the electrodes 100 are replaced can be avoided. Furthermore, as the sealing member 30 is arranged as described above, the sealing member 30 can be placed at a fixed position on the electrode 100. This prevents variations in the placement position of the sealing member 30 among multiple electrodes 100 when the electrodes 100 are replaced. As a result, even when the electrodes 100 are replaced, variations in the detection accuracy of the test substance among multiple electrodes 100 can be avoided.

[0035] The planar shape of the wetted surface of the electrode film 102 refers to the shape of the wetted surface of the electrode film 102 when viewed from above perpendicular to the main surface of the substrate 101. The planar area of ​​the protrusion 101c refers to the area of ​​the protrusion 101c when viewed from above perpendicular to the main surface of the substrate 101.

[0036] The component 40 is configured to cover the electrode 100 while it is supported by the support 20. The component 40 is made of a material that is insulating and does not corrode the electrode 100 even when a potential is applied to it while it is in contact with the test solution. The component 40 can be made of, for example, an engineering plastic such as PEEK resin, or an insulating material such as a composite resin, ceramic, glass, or plastic.

[0037] The member 40 has an opening 41 that exposes the electrode film 102 on the top surface of the protrusion 101c when the electrode 100 is covered. The planar shape of the opening 41 is preferably the same as the planar shape of the protrusion 101c. The planar shape of the opening 41 is the shape of the opening 41 when the member 40, which is covering the electrode 100 supported on the support 20, is viewed from above in a direction perpendicular to the main surface of the substrate 101. Furthermore, the size of the opening 41 is preferably such that when the electrode 100 is covered with the member 40, the inner periphery of the opening 41 is positioned on the sealing member 30 arranged around the protrusion 101c. This prevents the member 40 from coming into contact with the wetted surface of the electrode film 102, and as a result, contamination of the electrode film 102 can be reliably avoided. Furthermore, the size of the opening 41 is preferably the above size, and more preferably slightly larger than the diameter d1 of the protrusion 101c. This increases the contact area between the sealing member 30 and the member 40, thereby reliably preventing the occurrence of liquid leakage, as described later.

[0038] When an electrochemical reaction occurs on the surface of the electrode film 102, as shown in Figure 1(b), the structure 10 supports the electrode 100 on the support 20, places the sealing member 30 around the convex portion 101c, and covers the electrode 100 other than the wetted surface with the member 40.

[0039] In this state of the structure 10, contact of the test fluid with areas of the electrode 100 other than the wetted surface of the electrode film 102, for example, the area of ​​the electrode 100 from the sealing member 30 to the connection point 50 is prevented.

[0040] Furthermore, in this state of the structure 10, the sealing member 30 is held between the substrate 101 and the member 40 over the entire circumference of the protrusion 101c, and does not come into contact with the electrode film 102 (neither the surface nor the sides of the electrode film 102).

[0041] In the structure 10, the sealing member 30 does not come into contact with the electrode film 102, thus preventing contamination of the wetted surface of the electrode film 102. For example, contamination originating from the sealing member 30, such as dissolved substances, can be prevented from adhering to the wetted surface of the electrode film 102. As a result, a decrease in the detection accuracy of the substance being tested can be avoided.

[0042] Furthermore, as described above, the surface of the electrode film 102, which is composed of BDD polycrystalline material, is a sharp, uneven surface. By preventing the sealing member 30 from contacting the electrode film 102, damage to the sealing member 30 (or its surface) can be avoided, and as a result, leakage can be prevented. In this specification, "leakage" means a situation in which the test liquid can come into contact with areas of the electrode 100 other than the wetted surface of the electrode film 102.

[0043] Furthermore, as described above, the surface of the electrode film 102, which is composed of BDD polycrystalline material, is uneven. Therefore, in conventional methods of pressing the sealing member 30 against the surface of the electrode film 102, a minute gap is formed between the surface of the electrode film 102 and the sealing member 30, and the test fluid may leak out through this gap and come into contact with parts of the electrode film 102 other than the wetted surface. In contrast, in the structure 10 according to this embodiment, the sealing member 30 is held in place between the substrate 101 and the member 40 and does not come into contact with the electrode film 102. As a result, the occurrence of liquid leakage can be reliably prevented.

[0044] Furthermore, when a BDD electrode is used as electrode 100, as described above, a high voltage may be applied to electrode 100 or a large current may be passed through it, which may cause a violent electrochemical reaction on the surface of electrode film 102. Even if such a violent reaction occurs, the sealing member 30 is held in place between the substrate 101 and member 40 and does not come into contact with electrode film 102, thus preventing deterioration of the sealing member 30. As a result, leakage can be reliably prevented. In contrast, in the conventional method of pressing the sealing member 30 against the surface of electrode film 102, if a violent electrochemical reaction occurs on the surface of electrode film 102, the sealing member 30 may deteriorate, resulting in leakage.

[0045] Furthermore, applying a high voltage or a large current to the electrode 100 may cause the temperature of the electrode film 102 to change locally (become higher). Even if such a temperature change occurs, the sealing member 30 is held in place between the substrate 101 and the member 40 and does not come into contact with the electrode film 102, thus preventing deterioration of the sealing member 30. As a result, leakage can be reliably prevented.

[0046] Here, for reference, we will explain the case where electrodes other than BDD electrodes are used. For example, metal electrodes and carbon electrodes, which are formed by screen printing metal or carbon onto a substrate to create an electrode film, can be used as electrodes. Metal electrodes and carbon electrodes can have their electrode film surfaces formed very smoothly (a flat surface with almost no irregularities). Therefore, when metal electrodes or carbon electrodes are used as electrodes, leakage is unlikely to occur even with the conventional method of pressing the sealing member 30 against the surface of the electrode film. Also, because metal electrodes and carbon electrodes have lower chemical stability than BDD electrodes, they are rarely used in the same harsh environments and measurement conditions as BDD electrodes. In other words, metal electrodes and carbon electrodes are rarely subjected to the same high voltages or large currents as BDD electrodes. For this reason, problems such as the deterioration of the sealing member 30 described above rarely occur.

[0047] The structure 10 according to this embodiment can be suitably installed as an electrode for an electrochemical measurement sensor in an electrochemical reaction cell (electrolytic cell) provided in a dissolved ozone concentration measuring device or a dissolved chlorine concentration measuring device. As shown in Figure 4, the electrochemical reaction cell 200 is a housing having a hollow space 2 inside, and is configured to accommodate a test liquid (for example, a liquid containing ozone) in the hollow space 2. The cell 200 is provided with an inlet 3 for introducing the test liquid into the hollow space 2 and an outlet 4 for discharging the test liquid from the hollow space 2. A pipe 5 is connected to the inlet 3, and a pipe 6 is connected to the outlet 4. The test liquid is introduced into the cell 200 from the pipe 5 via the inlet 3 and discharged from the pipe 6 via the outlet 4.

[0048] A working electrode 7, a counter electrode 8, and a reference electrode 9 are arranged within the hollow space 2 of the cell 200. Each of the working electrode 7, counter electrode 8, and reference electrode 9 is positioned in contact with the test solution within the cell 200 (for example, at the bottom). Structure 10 is preferably used as the working electrode 7. Structure 10 can also preferably be used as the counter electrode 8 and the reference electrode 9. The shape, material, etc., of the counter electrode 8 and the reference electrode 9 can be appropriately determined depending on the substance being tested. The counter electrode 8 and the reference electrode 9 can each be electrodes made of metals such as Pt, Au, Cu, Pd, Ni, Ag, etc., or carbon electrodes, etc. The reference electrode 9 can also be, for example, a silver / silver chloride (Ag / AgCl) electrode, a standard hydrogen electrode, a reversible hydrogen electrode, a palladium-hydrogen electrode, a saturated calomel electrode, or an electrode made using silver chloride paste, etc. The working electrode 7, counter electrode 8, and reference electrode 9 are connected to the control unit 1. The control unit 1 is configured to adjust the potential of the working electrode 7 relative to the reference electrode 9 and to measure the amount of current flowing between the working electrode 7 and the counter electrode 8.

[0049] Furthermore, the structure 10 according to this embodiment can be suitably used not only as an electrode for an electrochemical measurement sensor installed in an electrochemical reaction cell 200, but also as an electrode for a general electrochemical measurement sensor. Figures 5(a) and 5(b) show another example of an electrochemical measurement sensor 201 using the structure 10 as an electrode. The electrochemical measurement sensor 201 shown in Figures 5(a) and 5(b) can also be used, for example, as a sensor for the rotating electrode method. Figures 5(c) and 5(d) show yet another example of an electrochemical measurement sensor 202 using the structure 10 as an electrode.

[0050] (2) Method for manufacturing electrodes for electrochemical reactions A method for manufacturing the electrochemical reaction electrode 100 described above, which comprises a substrate 101 and an electrode film 102, will be explained with reference to Figures 6 and 7.

[0051] (Preparing the circuit board) As the substrate 101, a conductive, flat substrate is prepared, for example, a flat single-crystal Si substrate having a circular outer shape in plan view.

[0052] (Pre-processing) As a pretreatment, at least one of the following treatments—seeding and scratching—is performed in air on one of the two main surfaces of the substrate 101, that is, the surface on which the BDD polycrystals will be grown (deposited). The "surface on which the BDD polycrystals will be grown" is the surface of the substrate 101 that will become the crystal growth surface, and is also the surface that will become the top surface of the substrate 101 as described above.

[0053] Seeding is a process in which diamond particles (seeds) are attached to the crystal growth surface by, for example, applying a solution (dispersion) containing diamond particles (preferably diamond nanoparticles) of a size of several nanometers to several tens of micrometers to the crystal growth surface, or by immersing the substrate 22 in the dispersion. Scratching is a process in which processing damage is created on the crystal growth surface, for example, by using diamond abrasive grains (diamond powder) of a size of several micrometers to create scratches on the crystal growth surface. By performing scratching, the nucleation density of diamonds can be increased.

[0054] (Formation of protrusions) After pretreatment, protrusions 101c are formed on the substrate 101 (see Figure 7(b)). Specifically, the surface of the substrate 101 that has undergone the pretreatment described above is subjected to grinding, for example, to cut out multiple (island-shaped) protrusions 101c from the upper surface of the substrate 101. Examples of grinding methods include grinding using a cup grinding wheel or ultrasonic grinding.

[0055] The flat area of ​​the resulting electrode 100 can be adjusted by adjusting the formation pattern of the protrusions 101c. Therefore, when forming the protrusions 101c, the formation pattern of the protrusions 101c should be such that the flat area of ​​the resulting electrode 100 becomes the predetermined flat area described above.

[0056] By performing grinding, seeds or scratches are removed from the areas of the pre-treated surface of the substrate 101 that are removed by grinding.

[0057] (Electrode film deposition) After forming the protrusions 101c, for example, a thermal filament CVD method using tungsten filaments is used to grow (deposit) a polycrystalline diamond on the crystal growth surface of the substrate 101 to provide the electrode film 102.

[0058] Diamond polycrystals can be grown using a thermal filament CVD apparatus 300, for example, as shown in Figure 6. The thermal filament CVD apparatus 300 has a growth chamber 301 inside and is equipped with an airtight container 303 made of a heat-resistant material such as quartz. A susceptor 308 for holding the substrate 101 is provided inside the growth chamber 301.

[0059] Gas supply pipes 332a to 332d are connected to the side wall of the airtight container 303. Flow controllers 341a to 341d and valves 343a to 343d are provided on the gas supply pipes 332a to 332d, in order from the upstream side of the gas flow. Nozzles 349a to 349d are connected to the downstream ends of the gas supply pipes 332a to 332d, respectively, to supply the respective gases supplied from the gas supply pipes 332a to 332d into the growth chamber 301. Nitrogen (N2) gas is supplied from gas supply pipe 332a to the growth chamber 301 via nozzle 349a. Hydrogen (H2) gas is supplied from gas supply pipe 332b to the growth chamber 301 via nozzle 349b. B-containing gas is supplied from gas supply pipe 332c to the growth chamber 301 via nozzle 349c. Examples of B-containing gases include trimethylboron (B(CH3)3, abbreviated as TMB) gas and diborane (B2H6) gas. C-containing gas is supplied into the growth chamber 301 from the gas supply pipe 332d via the nozzle 349d. Examples of C-containing gases include methane (CH4) gas and ethane (C2H6) gas. An exhaust pipe 330 for exhausting the growth chamber 301 is provided on the other side wall of the airtight container 303. A pump 331 is provided in the exhaust pipe 330. A temperature sensor 309 for measuring the temperature inside the growth chamber 301 is provided inside the airtight container 303. Also provided inside the airtight container 303 are a tungsten filament 310 and a pair of electrodes (e.g., molybdenum (Mo) electrodes) 311a and 311b that hold the tungsten filament 310 and are connected to a power source not shown. Each component of the thermal filament CVD apparatus 300 is connected to a controller 380, which is configured as a computer, and the processing procedures and processing conditions described later are controlled by a program executed on the controller 380.

[0060] First, the substrate 101 is placed into the growth chamber 301 (airtight container 303), which is configured to supply various gases including B-containing gas and C-containing gas, and held on the susceptor 308. Next, an electric current is passed between electrodes 311a and 311b to start heating the tungsten filament 310. As the tungsten filament 310 heats up, the substrate 101 held on the susceptor 308 also heats up. At the same time, while evacuating the growth chamber 301, the supply of H2 gas, B-containing gas (e.g., TMB gas), and C-containing gas (e.g., CH4 gas) into the growth chamber 301 is started. At this time, N2 gas may also be supplied into the growth chamber 301 if necessary. The heating of the tungsten filament 310, i.e., the heating of the substrate 22, the evacuating of the growth chamber 301, and the supply of various gases into the growth chamber 301 are continued at least until the growth of the diamond polycrystal is completed.

[0061] When the temperature of the filament 310 reaches a predetermined temperature (the growth temperature of the diamond polycrystal), the B-containing gas and C-containing gas decompose (thermal decomposition), and predetermined active species are generated. The predetermined active species are supplied onto the crystal growth surface of the substrate 101, causing the BDD polycrystal to grow on the substrate 101. After the temperature of the filament 310 reaches the growth temperature of the diamond polycrystal, the temperature of the filament 310 is controlled so that the temperature of the filament 310 is maintained at the growth temperature of the diamond polycrystal.

[0062] The following are examples of conditions for growing BDD polycrystalline materials. Pressure inside the growth chamber: 5 Torr to 50 Torr (665 Pa to 6650 Pa), preferably 10 Torr to 35 Torr (1330 Pa to 4655 Pa) Ratio of B-containing gas supply to C-containing gas supply (B-containing gas / C-containing gas): 0.003% or more and 0.8% or less Growth temperature: 600°C to 1000°C, preferably 650°C to 800°C. Filament temperature: 1800°C to 2500°C, preferably 2000°C to 2200°C. Growth time: 200 minutes or more and 500 minutes or less, preferably 300 minutes or more and 500 minutes or less Ratio of carbon-containing gas supply to H2 gas supply (carbon-containing gas / H2 gas): 2% to 5%

[0063] By growing BDD polycrystals under the above conditions, an electrode film 102 made of BDD polycrystals is formed on the substrate 101. As described above, seeds or scratches are removed from the areas of the pre-treated surface of the substrate 101 (the upper surface of the substrate 101) that have been ground away. Diamond polycrystals do not grow in the areas from which seeds or scratches have been removed. Therefore, in this embodiment, BDD polycrystals grow only on the top surface of the convex portion 101c.

[0064] After the growth of the diamond polycrystal is complete, the supply of each gas to the growth chamber 301 and the heating of the tungsten filament 310 are stopped. Then, once the temperature inside the growth chamber 301 has cooled to a predetermined temperature, the laminated substrate 101a is removed from the growth chamber 301 to the outside of the airtight container 303.

[0065] (Formation of conductive thin film) After the electrode film 102 is formed, a conductive thin film 103 is provided on the back surface of the substrate 101, for example, by vapor deposition. This results in a laminated substrate 100a, as shown in Figures 7(a) and 7(b), in which the substrate 101 and the electrode film 102 are laminated together.

[0066] (Disassembly of the circuit board) Next, the laminated substrate 100a is cut (divided) into a predetermined shape (for example, a specified chip shape) to obtain a chip-shaped electrode 100 comprising a substrate 101, an electrode film 102, and a conductive thin film 103. Specifically, the laminated substrate 100a (substrate 101) is cut along the cutting line shown by the dotted line L in Figure 7(a) using known methods such as laser processing methods such as laser scribing and laser dicing, machining methods, and etching. As a result, the laminated substrate 100a is divided into multiple small pieces. These small pieces then become electrodes 100 comprising a substrate 101, an electrode film 102, and a conductive thin film 103. After that, the obtained electrodes 100 may be cleaned as needed.

[0067] (3) Assembly of structures for electrochemical reactions An example of the assembly procedure for the electrochemical reaction structure 10 is described below.

[0068] First, prepare the electrode 100 having the above-described configuration, the support 20, the sealing member 30 (for example, an O-ring), and the member 40 having the opening 41.

[0069] Then, the conductive portion 21 is formed on one of the two main surfaces of the support 20, for example, by a vapor deposition method. Alternatively, a support 20 with the conductive portion 21 already formed may be prepared.

[0070] Furthermore, the sealing member 30 is positioned (set) so as to surround the protrusion 101c of the electrode 100. When setting the sealing member 30, the sealing member 30 may be fixed using an adhesive such as grease. In this case, the amount and application position of the grease should be adjusted so that the grease does not come into contact with the electrode film 102.

[0071] Furthermore, the electrode 100 is placed on the support 20 such that the conductive thin film 103 is in contact with the conductor portion 21, and the electrode 100 is supported on the support 20. Note that the electrode 100 may be placed on the support 20 after the sealing member 30 is set, or it may be placed on the support 20 before the sealing member 30 is set. The electrode 100 is supported on the support 20 without using a conductive adhesive, and without covering the connection point 50 between the conductive thin film 103 and the conductor portion 21 with an insulating resin or the like. In other words, the electrode 100 is detachably supported on the support 20.

[0072] Then, the electrode 100, which is supported by the support 20 and has the sealing member 30 set, is covered with the member 40 to prevent the test fluid from coming into contact with any part of the electrode 100 other than the wetted surface of the electrode film 102. This results in a structure 10 in the state shown in Figures 1(a) and 1(b).

[0073] (4) Effects According to this embodiment, one or more of the following effects can be obtained.

[0074] (a) The structure 10 is configured such that when an electrochemical reaction occurs on the surface of the electrode film 102, the sealing member 30 is held between the substrate 101 and the member 40 over the entire circumference in the circumferential direction of the protrusion 101c, and does not come into contact with the electrode film 102.

[0075] Since the sealing member 30 does not come into contact with the electrode film 102, contamination of the wetted surface of the electrode film 102 can be avoided. As a result, a decrease in the sensitivity of the electrode 100, for example, a decrease in the detection accuracy of the substance being tested, can be avoided.

[0076] Furthermore, because the sealing member 30 does not come into contact with the electrode film 102, even if the electrode 100 is a BDD electrode, the sealing member 30 (or its surface) will not be damaged by the sharp irregularities on the surface of the electrode film 102. As a result, leakage can be prevented.

[0077] Furthermore, by sandwiching and holding the sealing member 30 between the substrate 101 and the member 40, it is possible to reliably prevent the test fluid from coming into contact with parts of the electrode 100 other than the wetted surface of the electrode film 102, i.e., prevent leakage. In other words, because the sealing member 30 is not held on the electrode film 102, even if the electrode 100 is a BDD electrode, it is possible to avoid the formation of minute gaps between the surface irregularities of the electrode film 102 and the sealing member 30, as would occur if the sealing member 30 were held on the surface of the electrode film 102. As a result, leakage can be reliably prevented.

[0078] Furthermore, because the sealing member 30 is sandwiched and held between the substrate 101 and the member 40 and does not come into contact with the electrode film 102, deterioration of the sealing member 30 can be avoided even if a violent electrochemical reaction occurs on the surface of the electrode film 102 due to the application of a high voltage or the flow of a large current. As a result, leakage can be reliably prevented.

[0079] Furthermore, because the sealing member 30 is sandwiched and held between the substrate 101 and the member 40 and does not come into contact with the electrode film 102, deterioration of the sealing member 30 can be avoided even if the temperature of the electrode film 102 rises locally due to the application of a high voltage or the flow of a large current. As a result, leakage can be reliably prevented.

[0080] (b) Even when a BDD electrode is used as electrode 100, leakage can be prevented, allowing the structure 10 to be suitably used for measuring dissolved ozone concentration and dissolved chlorine concentration, and ensuring accurate concentration measurement. However, if leakage occurs when the structure 10 is used to measure dissolved ozone concentration and dissolved chlorine concentration, and a highly oxidizing test solution containing ozone or chlorine comes into contact with the conductive thin film 103 or the conductor part 21, corrosion of the conductive thin film 103 or the conductor part 21 will progress rapidly, making accurate measurement impossible.

[0081] (c) The flat surface area of ​​the electrode 100 is larger than the size of the sealing member 30, which further ensures that liquid leakage occurs. If the flat surface area of ​​the electrode 100 is not larger than the size of the sealing member 30, a small gap may form between the substrate 101 and the sealing member 30, which could cause liquid leakage.

[0082] (d) In structure 10, the electrode 100 is detachably supported on the support 20. This allows for easy replacement of only the electrode 100 when replacing it.

[0083] (e) By arranging the sealing member 30 to surround the convex portion 101c, the planar shape and wetted area of ​​the wetted surface of the electrode film 102 can be defined independently of the sealing member 30. Therefore, by keeping the planar shape and planar area of ​​the convex portion 101c constant among multiple electrodes 100, the planar shape and wetted area of ​​the wetted surface of the electrode film 102 can be kept constant. As a result, even when the electrodes 100 are replaced, variations in the wetted area among multiple electrodes 100 can be avoided, and as a result, variations in the detection accuracy of the substance being tested can be reliably avoided.

[0084] (f) The sealing member 30 is arranged to surround the convex portion 101c, so that even when the electrode 100 is replaced, the sealing member 30 can be reliably positioned in a fixed location on the electrode 100. This prevents variations in the wetted area and the position of the sealing member 30 among multiple electrodes 100 when the electrode 100 is replaced, and as a result, it is possible to reliably prevent variations in the detection accuracy of the test substance among multiple electrodes 100.

[0085] (g) The size of the opening 41 in member 40 is such that when member 40 covers the electrode 100, the inner edge of the opening 41 is positioned on the sealing member 30 arranged around the protrusion 101c, thereby preventing member 40 from coming into contact with the wetted surface. As a result, contamination of the electrode film 102 can be reliably avoided. Furthermore, the size of the opening 41 is such that it is slightly larger than the diameter d1 of the protrusion 101c, thereby increasing the contact area between the sealing member 30 and member 40, and reliably preventing liquid leakage.

[0086] Here, for reference, a conventional method is described in which a sealing member 30 is placed on the surface of the electrode film 102, and a predetermined jig is pressed against the sealing member 30 from above to prevent contact of the test fluid with the area extending from the sealing member 30 to the connection point 50. In such conventional methods, the degree to which the sealing member 30 is pressed when the predetermined jig is pressed against it may vary, or the sealing member 30 may shift from its predetermined position on the surface of the electrode film 102. As a result, when the electrodes are replaced, the wetted area, the planar shape of the wetted surface, the position of the sealing member 30, etc. may vary among multiple electrodes, resulting in variations in the detection accuracy of the test substance. In contrast, in this embodiment, the sealing member 30 is arranged to surround the convex portion 101c. As a result, the conventional problems can be solved, and even when the electrodes 100 are replaced, variations in the wetted area and the position of the sealing member 30, etc., among multiple electrodes 100 can be avoided.

[0087] (5) Variant This embodiment can be modified as shown in the following examples. In the following descriptions of the modifications, the same reference numerals are used for components identical to those in the above embodiment, and their descriptions are omitted. Furthermore, the above embodiment and the following modifications can be combined in any way.

[0088] (Variation 1) In the above-described embodiment, an electrode 100 was prepared by performing a predetermined grinding process on the upper surface of the substrate 101 to cut out a protrusion 101c on the upper surface of the substrate 101, but the invention is not limited to this. Figures 8(a) and 8(b) show schematic diagrams of the electrode 100A according to this modified example.

[0089] In electrode 100A, the protrusion 101c is formed by the substrate 101 located inside an annular (e.g., circular) groove 101g in which the sealing member 30 can be placed (accommodated). That is, in electrode 100A, the protrusion 101c is provided by forming an annular groove 101g on the upper surface of the substrate 101. In electrode 100A, the diameter d1 of the protrusion 101c in plan view coincides with the inner diameter d2 of the groove 101g (see Figure 8(a)), and the height h1 of the protrusion 101c coincides with the depth h2 of the groove 101g (see Figure 8(b)).

[0090] The inner diameter d2 (hereinafter, inner diameter d2 of groove 101g), outer diameter D, width w, and depth h2 of groove 101g can each be set to a size corresponding to the sealing member 30. If, for example, an O-ring is used as the sealing member 30, the size of groove 101g (inner diameter d2, outer diameter D, width w, and depth h2 of groove 101g) can be set to a size conforming to the O-ring standard. An example of the size of groove 101g (inner diameter d2, outer diameter D, width w, and depth h2) is shown in Table 2 below. In Table 2, "d dimension" refers to the size of the inner diameter d2 of groove 101g, and "D dimension" refers to the size of the outer diameter D of groove 101g.

[0091] [Table 2]

[0092] The method for manufacturing the electrode 100A according to this modified example will be described below with reference to Figures 9(a) and 9(b).

[0093] First, as in the embodiment described above, a substrate 101 is prepared, and at least one of the following treatments is performed as a pretreatment on the upper surface (crystal growth surface) of the substrate 101, which is one of the two main surfaces of the substrate 101: seeding treatment and scratch treatment.

[0094] After pretreatment, the protrusions 101c are formed. Instead of the grinding process described above, groove formation is performed to form the protrusions 101c. Specifically, groove formation is performed on the surface of the substrate 101 that has undergone the pretreatment described above, forming multiple annular (for example, circular) grooves 101g on the upper surface of the substrate 101 in a plan view. As a result, multiple (island-shaped) protrusions 101c are formed on the upper surface of the substrate 101.

[0095] Examples of groove formation processes include processing by laser irradiation and processing by etching using a photolithography process. Furthermore, the planar area of ​​the resulting electrode 100A can be adjusted by adjusting the formation pattern of the groove 101g. Therefore, when forming the groove 101g, the formation pattern of the groove 101g should be set to a pattern such that the planar area of ​​the resulting electrode 100A becomes the predetermined planar area mentioned above. In addition, by forming the groove 101g, seeds or scratches are removed from the area of ​​the pre-treated surface of the substrate 101 in which the groove 101g is formed (within the groove 101g).

[0096] After forming the protrusion 101c, the electrode film 102 is formed by growing a BDD polycrystal on the upper surface of the substrate 101 using the same procedure and conditions as described above. As described above, since seeds or scratches have been removed from within the groove 101g, the diamond polycrystal does not grow within the groove 101g. Therefore, in this modified example, the BDD polycrystal grows on the upper surface of the substrate 101 in locations other than where the groove 101g is formed. That is, in this modified example, the electrode film 102 is formed on the upper surface of the substrate 101 located inside the annular groove 101g (i.e., on the top surface of the protrusion 101c of the substrate 101), and on the upper surface of the substrate 101 located outside the annular groove 101g.

[0097] After forming the electrode film 102, a conductive thin film 103 is provided on the back surface of the substrate 101, similar to the embodiment described above. This results in a laminated substrate 100b in which the substrate 101, the electrode film 102, and the conductive thin film 103 are laminated together.

[0098] After providing the conductive thin film 103, the laminated substrate 100b is cut into a predetermined shape (for example, a specified chip shape) to obtain an electrode 100A comprising a substrate 101, an electrode film 102, and the conductive thin film 103. Specifically, first, using known methods such as laser processing methods like laser scribing and laser dicing, machining methods, and etching, a concave groove 100g (for example, a laser-processed groove, a scribed groove, or a dicing groove) is formed on the laminated substrate 100b from the side of the conductive thin film 103 along the break line shown by the dotted line L' in Figure 9(b). This yields a laminated substrate 100b as shown in Figures 9(a) and 9(b).

[0099] The following are examples of laser irradiation conditions when forming a groove of 100g using a laser processing method. Laser beam: 532nm, 5W, 10kHz, spot diameter 2μm Scanning speed: 5 mm / sec to 20 mm / sec, preferably 7 mm / sec to 15 mm / sec. Number of scans: 15 to 50 times

[0100] Next, the laminated substrate 100b is bent along the groove 100g, breaking the substrate 101 and electrode film 102. This divides the laminated substrate 100b into several small pieces. These pieces then become electrodes 100A, each comprising the substrate 101, electrode film 102, and conductive thin film 103. Afterwards, the resulting electrodes 100A may be washed as needed.

[0101] Furthermore, when forming the groove 100g, it is also conceivable to form the groove 100g from the electrode film 102 side of the laminated substrate 100b. However, since the electrode film 102, which is composed of BDD polycrystalline material, is highly hard, it is difficult to form the groove 100g from the electrode film 102 side using laser processing or machining methods. Another method that can be considered is to form the substrate 101 and electrode film 102 into a predetermined shape by dry etching or the like to divide the laminated substrate 100b. However, dividing the laminated substrate 100b, which has a highly hard electrode film 102 composed of BDD polycrystalline material, into a predetermined shape by dry etching or the like would increase costs. In addition, since dry etching may cause altered regions in the electrode film 102, it is necessary to devise a way to prevent altered regions from occurring on the wetted surface of the electrode film 102. Note that an "altered region" is a region in the electrode film 102 where the bonding form between carbons is sp 3 Not a bonding structure (diamond structure), but sp 2 This refers to a region that has a bonded structure (graphite structure).

[0102] The assembly procedure for the structure 10 having the electrode 100A is the same as in the above-described embodiment, except that when arranging the sealing member 30 to surround the protrusion 101c of the electrode 100A, the sealing member 30 is placed (housed) in the groove 101g. This results in the structure 10 shown in Figure 10.

[0103] Even when the structure 10 is equipped with an electrode 100A, when an electrochemical reaction occurs on the surface of the electrode film 102, the structure 10 supports the electrode 100A on the support 20, positions the sealing member 30 so as to surround the convex portion 101c, and covers the area of ​​the electrode 100A other than the wetted surface with the member 40. In this state, the structure 10 is also prevented from contacting the area of ​​the electrode 100A other than the wetted surface of the electrode film 102 with the test fluid. Furthermore, in this state, the structure 10 is also held between the substrate 101 and the member 40 over the entire circumference of the convex portion 101c and does not come into contact with the electrode film 102 (neither the surface nor the sides of the electrode film 102). Therefore, even when the structure 10 is equipped with an electrode 100A, the same effects as in the above-described embodiment can be obtained.

[0104] Furthermore, in this modified example, since the sealing member 30 is placed within the groove 101g, the sealing member 30 can be positioned more reliably at a fixed location on the electrode 100A compared to the electrode 100 described above. This makes it possible to more reliably avoid variations in the wetted area and the position of the sealing member 30 among multiple electrodes 100A when the electrode 100A is replaced. As a result, it is possible to more reliably avoid variations in the detection accuracy of the substance being tested among multiple electrodes 100A.

[0105] In this modified example, when the laminated substrate 100b breaks, that is, when the substrate 101 and the electrode film 102 break, for example, the edge of the electrode film 102 (a part of the electrode film 102 located outside the groove 101g) may peel off. However, even in this modified example, the wetted surface of the electrode film 102 is the surface of the electrode film 102 located on the top surface of the protrusion 101c, that is, the surface of the electrode film 102 located inside the groove 101g. In other words, even in this modified example, the planar shape and wetted area of ​​the wetted surface of the electrode film 102 are determined by the planar shape and planar area of ​​the protrusion 101c. Therefore, even if, for example, a part of the electrode film 102 located outside the groove 101g peels off when the laminated substrate 100b breaks, it does not affect the planar shape and wetted area of ​​the wetted surface of the electrode film 102. In this modified example, by keeping the planar shape and surface area of ​​the protrusions 101c constant among multiple electrodes 100A, the planar shape and surface area of ​​the wetted surface of the electrode film 102 can be kept constant. As a result, even when the electrodes 100A are replaced, variations in the detection accuracy of the substance to be tested among multiple electrodes 100A can be avoided.

[0106] (Modification 2) In the embodiments and modifications described above, examples were given in which a protrusion 101c is formed on the upper surface of the substrate 101 by performing a predetermined grinding process or a predetermined groove forming process on the upper surface of the substrate 101, but the invention is not limited to these.

[0107] For example, multiple protrusions 101c may be machined from the upper surface of the substrate 101 by blasting or dry etching using a predetermined mask, or multiple protrusions 101c may be formed by forming multiple annular grooves 101g on the upper surface of the substrate 101. For example, metal particles (metal beads) can be suitably used as the abrasive material for blasting. SiC abrasive particles can also be used as the abrasive material. In this modified example, seeds or scratches are removed from the areas machined by blasting or dry etching, or from the areas where grooves 101g are formed, on the pre-treated surface of the substrate 101 by blasting or dry etching. Except for performing blasting or dry etching instead of predetermined grinding or groove formation, the method can be the same as the above-described embodiment and modified example. This allows for the production of electrodes similar to the electrodes 100 shown in Figures 2(a) and 2(b), and the electrodes 100A shown in Figures 8(a) and 8(b), and provides the same effects as the above-described embodiment and modified example.

[0108] (Variation 3) In the embodiments and modifications described above, examples were given in which the structure 10 is used as an electrode for an electrochemical measurement sensor installed in an electrochemical reaction cell 200, or as an electrode for other general electrochemical measurement sensors 201 and 202, but it is not limited to these. For example, the structure 10 may be attached as an electrode for an electrochemical measurement sensor to a pipe configured through which a test liquid flows, or to a housing configured to hold a test liquid inside. Below, a structure 10 configured to be attachable to such a pipe or housing, i.e., a structure 10A according to this modification, will be described with reference to Figures 11(a) and 11(b).

[0109] As shown in Figures 11(a) and 11(b), the structure 10A comprises the electrode 100 (or electrode 100A) described above, a support 20, and a sealing member 30, but does not include the member 40 described above. In the structure 10A, an electrode pad is provided as a conductor portion 21 on the surface of the support 20 that supports the electrode 100. In addition, the piping 203 and housing 204 to which the structure 10A is attached are provided with openings 203a and 204a, respectively, that expose the electrode film 102 on the top surface of the protrusion 101c. The size of the openings 203a and 204a can be the same as the size of the opening 41 described above. Thus, even in this modified example, the planar shape and area of ​​the wetted surface of the electrode film 102 can be defined by the planar shape and area of ​​the protrusion 101c.

[0110] The assembly procedure for structure 10A is as follows. First, the sealing member 30 is positioned (set) so as to surround the protrusion 101c of the electrode 100. This ensures that even when the electrode 100 is replaced, the sealing member 30 can be reliably positioned in a fixed location on the electrode 100. Then, the electrode 100 is supported on the support 20 so that the conductive thin film 103 of the electrode 100 is in contact with the conductor portion 21. The sealing member 30 can be set at either the time before or after supporting the electrode 100 on the support 20. In structure 10A, the electrode 100 is also detachably attached to the support 20. That is, the electrode 100 is supported on the support 20 without using conductive adhesive or insulating resin. This gives rise to structure 10A. Then, the structure 10A, which is supported by the support 20 and includes an electrode 100 with a sealing member 30 set on it, is attached to the outer circumferential wall of the piping 203 or housing 204 such that the wetted surface of the electrode film 102 is exposed to the inside of the piping 203 or housing 204 through the openings 203a and 204a.

[0111] When the structure 10A is attached to the pipe 203 or housing 204, the sealing member 30 is sandwiched between the outer circumferential wall of the pipe 203 or the outer circumferential wall of the housing 204 and the electrode 100, and is held in contact with the outer circumferential wall of the pipe 203 or the outer circumferential wall of the housing 204 and the substrate 101 over the entire circumference of the protrusion 101c. In this way, even when the structure 10 is attached to the pipe 203 or housing 204, the sealing member 30 does not come into contact with the electrode film 102.

[0112] From the above, the same effects as those described above in the embodiment and modified examples can be obtained in structure 10A.

[0113] (Modification 4) In the above embodiments and modifications, the structures 10 and 10A are used as electrodes for an electrochemical measurement sensor, i.e., the electrodes 100 and 100A are relatively small (for example, the planar area of ​​electrode 100 (electrode 100A) provided by the structures 10 and 10A is 4 mm²). 2 200mm or more 2 The following describes an example in which the electrode 100 (electrode 100A) has a tip shape, but the invention is not limited thereto. Structures 10 and 10A can also be used, for example, as electrolytic electrodes.

[0114] When structures 10 and 10A are used as electrolytic electrodes, electrode 100 (electrode 100A), and by extension, structures 10 and 10A, may be formed to be larger than when they are used as electrodes for electrochemical measurement sensors. For example, electrode 100 (electrode 100A) may have a planar area of ​​2 cm². 2 Super 400cm 2 Preferably 25cm 2 More than 100cm 2 It may be formed in the following plate-like shape.

[0115] In this modified example, the thickness of the substrate 101 (at its thickest point) can be, for example, 3 mm or more. There is no particular upper limit to the thickness of the substrate 101, but from the viewpoint of suppressing the enlargement of the electrode 100, the thickness of the substrate 101 can be 10 mm or less, preferably 5 mm or less.

[0116] In this modified example, a (flat) packing or the like, manufactured to suit the usage configuration, is preferably used as the sealing member 30. Therefore, in this modified example, the size of the protrusion 101c (diameter d1, height h1) and the size of the groove 101g (d dimension, D dimension, width w, depth h2) can be appropriately determined according to the flat area of ​​the substrate 101 on which the electrode 100 (electrode 100A) is provided. In this modified example, from the viewpoint of reliably preventing liquid leakage with the sealing member 30, it is preferable that the size of the protrusion 101c and the size of the groove 101g be determined such that the shortest width of the outer region of the electrode 100 (electrode 100A) is, for example, 0.5 times or more, preferably 3 times or more, the wire diameter (width) of the sealing member 30. Also, in this modified example, the size of the sealing member 30 (thickness, inner diameter, width, etc.) is appropriately determined according to the size of the protrusion 101c and the size of the groove 101g. For example, the thickness of the sealing member 30 is 1.5 mm or more and is less than half the thickness of the substrate 101 (at its thickest point), the inner diameter of the sealing member 30 is the same as the diameter d1 of the protrusion 101c or the d dimension of the groove 101g, or slightly larger than the diameter d1 or the d dimension, and the width of the sealing member 30 is, for example, 5 mm or more. Furthermore, the upper limit of the width of the sealing member 30 is, for example, a size that can secure the minimum width of the outer region of the electrode 100 (electrode 100A) described above, which is 0.5 times or more, preferably 3 times or more, the wire diameter (width) of the sealing member 30.

[0117] In this modified example, if an increase in the size of electrode 100 (electrode 100A) is permitted (i.e., if the substrate 101 can be thicker), an O-ring of the G standard (wire diameter 3.1 mm or 5.7 mm) with inner diameter and wire diameter defined by JIS B2401-1 can be used as the sealing member 30.

[0118] Other configurations can be the same as those described above in the embodiments and modifications.

[0119] In this modified example, the substrate 101 is provided with a protrusion 101c, and the structures 10 and 10A are configured such that when an electrochemical reaction occurs on the surface of the electrode film 102, the sealing member 30 is sandwiched and held between the substrate 101 and the member 40 around the entire circumference of the protrusion 101c, and does not come into contact with the electrode film 102 (neither the surface nor the sides of the electrode film 102). Therefore, the same effects as those of the above-described embodiment and modified example can be obtained in this modified example as well.

[0120] (Variation 5) Furthermore, when structures 10 and 10A are used as electrolytic electrodes, the planar area of ​​electrode 100 (electrode 100A) is, for example, 400 cm². 2 super 4m 2 Preferably 1m 2 More than 4m 2 The following modifications may also be made. In this modified example, the thickness of the substrate 101 (at its thickest point) can be, for example, 10 mm or more, preferably 15 mm or more. There is no particular upper limit to the thickness of the substrate 101, but from the viewpoint of suppressing the enlargement of the electrode 100 (electrode 100A), the thickness of the substrate 101 can be 30 mm or less, preferably 20 mm or less. Thus, the electrode 100 (electrode 100A) may be formed in a plate shape.

[0121] In this modified example, suitable seal members 30 may include, for example, O-rings of the V standard with a wire diameter of 10 mm as defined by JIS B2401-1, or O-rings of the P standard with a wire diameter of 8.4 mm. Alternatively, gaskets of a predetermined size may also be suitable as seal members 30.

[0122] In this modified example, the size of the protrusion 101c (diameter d1, height h1) and the size of the groove 101g (d dimension, D dimension, width w, depth h2) are appropriately determined according to the inner diameter and wire diameter of the sealing member 30. Specifically, when the structure 10 has the configuration shown in Figures 2(a) and 2(b), the diameter d1 of the protrusion 101c is appropriately determined according to the inner diameter of the O-ring, and the height h1 of the protrusion 101c is appropriately determined according to the wire diameter of the O-ring. For example, it is preferable that the diameter d1 of the protrusion 101c is slightly larger than the inner diameter of the O-ring, and it is preferable that the height h1 of the protrusion 101c is slightly smaller than the wire diameter of the O-ring. Furthermore, if the structure 10A has the configuration shown in Figures 8(a) and 8(b), the inner diameter d2 (d dimension) of the groove 101g is appropriately determined according to the inner diameter of the O-ring, the outer diameter D (D dimension) is appropriately determined according to the outer diameter of the O-ring (= inner diameter + (wire diameter × 2)), and the width w and depth h2 are appropriately determined according to the wire diameter of the O-ring. For example, it is preferable that the d dimension of the groove 101g is slightly larger than the inner diameter of the O-ring, the D dimension of the groove 101g is slightly smaller than the outer diameter of the O-ring, the width w of the groove 101g is slightly larger than the wire diameter of the O-ring, and the depth h2 of the groove 101g is slightly smaller than the wire diameter of the O-ring.

[0123] Other configurations can be the same as those described above in the embodiments and modifications.

[0124] In this modified example, the substrate 101 is provided with a protrusion 101c, and when the structure 10 generates an electrochemical reaction on the surface of the electrode film 102, the sealing member 30 is held between the substrate 101 and the member 40 over the entire circumference of the protrusion 101c, and is configured so as not to come into contact with the electrode film 102 (neither the surface nor the sides of the electrode film 102). Therefore, the same effects as those of the above-described embodiment and modified example can be obtained in this modified example as well.

[0125] Furthermore, the plate-shaped electrode 100 (electrode 100A) according to this modified example can be suitably used for electrolytic reduction, electrolytic oxidation, and electrolytic synthesis of organic compounds. In other words, the structures 10 and 10A having the electrode 100 (electrode 100A) of this modified example can be suitably used for the electrolytic synthesis of organic compounds and for flow electrolysis. Specifically, the structures 10 and 10A having the electrode 100 (electrode 100A) according to this modified example can be suitably used, for example, to electrochemically produce formic acid by reducing carbon dioxide, to electrolytically synthesize various organic compounds, and to treat wastewater using various electrochemical advanced oxidation processes (EAOP).

[0126] (Experimental variation 6) In the embodiments and modifications described above, an example was given in which the electrode 100 (electrode 100A) has a conductive thin film 103, but the invention is not limited thereto. Since the substrate 101 is conductive, the electrode 100 (electrode 100A) does not need to have a conductive thin film 103. That is, the electrode 100 (electrode 100A) may be supported on the support 20 such that the back surface of the substrate 101 is in contact with the conductive portion 21 of the support 20. However, as described above, the electrode 100 (electrode 100A) is an electrode that can be attached to and detached from the support 20. For this reason, when the electrode 100 (electrode 100A) is removed from the support 20, a native oxide film such as an SiO2 film may be formed on the exposed surface of the substrate 101, such as a Si substrate. Since native oxide films are insulating, if the electrode 100 (electrode 100A) does not have a conductive thin film 103, additional processing such as polishing may be required to ensure conductivity between the electrode 100 (electrode 100A) and the conductive portion 21. The presence of a conductive thin film 103 on electrode 100 (electrode 100A) is preferable because it avoids the formation of a native oxide film at the location of electrode 100 (electrode 100A) that is electrically connected to the conductor portion 21, thereby ensuring reliable electrical connection between electrode 100 (electrode 100A) and the conductor portion 21.

[0127] (Example 7) In the embodiments and modifications described above, examples were given in which the electrode film 102 is composed of BDD polycrystalline material, but the invention is not limited thereto. For example, the electrode film 102 may be composed of diamond-like carbon (DLC).

[0128] <Preferred aspects of this disclosure> The following are preferred embodiments of this disclosure.

[0129] (Note 1) According to one aspect of this disclosure, A conductive substrate, and a chip-shaped or plate-shaped electrode having an electrode film made of boron-doped polycrystalline diamond on one of the two main surfaces of the substrate, (Annular) sealing member, Equipped with, The substrate has (island-shaped) protrusions on the surface having the electrode film, The electrode film is provided at least on the top surface of the convex portion, The sealing member is arranged so as to surround the periphery of the protrusion. A structure for electrochemical reactions is provided.

[0130] (Note 2) The structure of Appendix 1, preferably, The electrode further comprises a member covering the electrode, The member covering the electrode has an opening that exposes the electrode film on the top surface of the protrusion while covering the electrode. The sealing member is sandwiched between the electrode and the member covering the electrode, and is held in contact with the substrate and the member covering the electrode over the entire circumference in the circumferential direction of the protrusion.

[0131] (Note 3) The structure of Appendix 2, preferably, The support further comprises a support for the electrode, The support has a conductive portion that is electrically connected to the electrode, The electrode has a conductive thin film on the other of the two main surfaces of the substrate, which is different from the other main surface. The member covering the electrode is configured to cover the portion of the electrode other than the portion that can contribute to the electrochemical reaction, while the electrode is supported on the support so that the conductive thin film is electrically connected to the conductor portion.

[0132] (Note 4) The structure of Appendix 1, preferably, The electrode is mounted in a pipe configured to allow the test fluid to flow through it and having an opening that exposes the electrode film on the top surface of the protrusion, or in a housing configured to hold the test fluid internally and having an opening that exposes the electrode film on the top surface of the protrusion. The sealing member is sandwiched between the outer circumferential wall of the pipe or the outer circumferential wall of the housing and the electrode, and is held in contact with the outer circumferential wall of the pipe or the outer circumferential wall of the housing and the substrate over the entire circumference in the circumferential direction of the protrusion.

[0133] (Note 5) The structure of Appendix 4, preferably, The electrode has a conductive thin film on the other of the two main surfaces of the substrate, which is different from the other main surface. The electrode is supported on a support having a conductive portion, such that the conductive thin film is electrically connected to the conductive portion.

[0134] (Note 6) A structure described in any one of the appendices 1 to 5, preferably, The electrode is configured to be detachable from the support.

[0135] (Note 7) According to other aspects of this disclosure, A conductive, flat substrate, The substrate comprises an electrode film made of boron-doped polycrystalline diamond on one of its two main surfaces, The substrate has (island-shaped) protrusions on the surface having the electrode film, The electrode film is provided at least on the top surface of the convex portion. Tip-shaped or plate-shaped electrodes for electrochemical reactions are provided.

[0136] (Note 8) According to yet another aspect of this disclosure, An electrochemical reaction cell or electrochemical measurement sensor is provided, which is equipped with the electrochemical reaction structure described in any one of the appendices 1 to 6.

[0137] (Note 9) According to yet another aspect of this disclosure, The process of preparing a conductive substrate, A step of performing a seeding (seeding) treatment or scratching (scratching) treatment on one of the two main surfaces of the substrate, A step of grinding the surface of the substrate that has undergone seeding or scratching to remove (island-shaped) protrusions from the surface, or forming grooves on the surface to form (island-shaped) grooves on the surface, A step of forming an electrode film made of boron-doped polycrystalline diamond on the surface of the substrate that has undergone seeding or scratching treatment, A step of cutting the substrate on which the electrode film has been formed into a predetermined chip shape or plate shape, A method for manufacturing an electrochemical reaction electrode having [a certain characteristic] is provided. [Explanation of Symbols]

[0138] 10,10A Electrochemical Reaction Structure 20 Support 21 Conductor section 30 sealing member 40. Component covering an electrode for an electrochemical reaction. 41 Aperture 50 Electrical connection points between electrodes and conductors Electrode for electrochemical reactions (100A, 100A) 101 circuit board 101c protrusion 101g groove 102 Electrode membrane 103 Conductive Thin Film 200 Electrochemical reaction cells 201,202 Sensors for electrochemical measurement

Claims

1. A conductive substrate, and a chip-shaped or plate-shaped electrode having an electrode film made of boron-doped polycrystalline diamond on one of the two main surfaces of the substrate, sealing member and Equipped with, The substrate has a protrusion on the surface having the electrode film, The electrode film is provided at least on the top surface of the convex portion, The sealing member is arranged so as to surround the periphery of the protrusion. Structures for electrochemical reactions.

2. The electrode further comprises a member covering the electrode, The member covering the electrode has an opening that exposes the electrode film on the top surface of the protrusion while covering the electrode. The sealing member is sandwiched between the electrode and the member covering the electrode, and is held in contact with the substrate and the member covering the electrode over the entire circumference in the circumferential direction of the protrusion. The electrochemical reaction structure according to claim 1.

3. The support further comprises a support for the electrode, The support has a conductive portion that is electrically connected to the electrode, The electrode has a conductive thin film on the other of the two main surfaces of the substrate, which is different from the other main surface. The member covering the electrode is configured to cover the portion of the electrode other than the portion that can contribute to the electrochemical reaction, while the electrode is supported on the support so that the conductive thin film is electrically connected to the conductor portion. The electrochemical reaction structure according to claim 2.

4. The electrode is mounted in a pipe configured to allow the test fluid to flow through it and having an opening that exposes the electrode film on the top surface of the protrusion, or in a housing configured to hold the test fluid internally and having an opening that exposes the electrode film on the top surface of the protrusion. The sealing member is sandwiched between the outer circumferential wall of the pipe or the outer circumferential wall of the housing and the electrode, and is held in contact with the outer circumferential wall of the pipe or the outer circumferential wall of the housing and the substrate over the entire circumference of the protrusion. The electrochemical reaction structure according to claim 1.

5. The electrode has a conductive thin film on the other of the two main surfaces of the substrate, which is different from the other main surface. The electrode is supported on a support having a conductive portion, such that the conductive thin film is electrically connected to the conductive portion. The electrochemical reaction structure according to claim 4.

6. The electrochemical reaction structure according to claim 3 or 5, wherein the electrode is configured to be detachably attached to the support.

7. A conductive, flat substrate, The substrate comprises an electrode film made of boron-doped polycrystalline diamond on one of its two main surfaces, The substrate has a protrusion on the surface having the electrode film, The electrode film is provided at least on the top surface of the convex portion. Tip-shaped or plate-shaped electrodes for electrochemical reactions.

8. An electrochemical reaction cell equipped with the electrochemical reaction structure described in claim 1.

9. An electrochemical measurement sensor equipped with the electrochemical reaction structure described in claim 1.

10. The process of preparing a conductive substrate, A step of performing a seeding process or scratching process on one of the two main surfaces of the substrate, A step of grinding the surface of the substrate that has undergone seeding or scratching to remove protrusions from the surface, or forming grooves on the surface by performing a groove-forming process, A step of forming an electrode film made of boron-doped polycrystalline diamond on the surface of the substrate that has undergone seeding or scratching treatment, A step of cutting the substrate on which the electrode film has been formed into a predetermined chip shape or plate shape, A method for manufacturing an electrode for an electrochemical reaction, comprising the characteristics of an electrode.

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