Electrode, chemical reactor and processing method for target substance

Abstract

To provide an electrode advantageous from the perspective of facilitating the activation of an enzyme or a coenzyme.SOLUTION: An electrode 1a activates an enzyme or a coenzyme by electron transfer with at least one member selected from the group consisting of an enzyme and a coenzyme. The electrode 1a contains platinum black and comprises a layer 14 that forms the surface of the electrode 1a. In the X-ray diffraction (XRD) pattern of surface 1s, a proportion P111 is 60% or more. The proportion P111 is the proportion of the maximum diffraction intensity peak originating from the platinum (111) plane in the total sum of maximum diffraction intensity peaks originating from the platinum (111), platinum (200), platinum (220), and platinum (311) planes.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present disclosure relates to an electrode, a reactor, and a method for treating a target material. [Background technology]

[0002] Electrodes for electrochemical reactions involving enzymes are known.

[0003] For example, Patent Document 1 describes an electrode for electrochemical measurements. In this electrode for electrochemical measurements, electrical wiring is formed on a composite material in which a metal oxide is dispersed in a platinum or platinum alloy matrix. The metal oxide is an oxide of a metal selected from the group consisting of zirconium, tantalum, and niobium. In this electrode for electrochemical measurements, the orientation rate of one of multiple crystal orientations is 80% or more. For example, ammonia produced by the action of urease is further treated with glutamate dehydrogenase in the presence of β-nicotinamide adenine dinucleotide (NADH) and potassium ferricyanide. The potassium ferrocyanide produced in this way can be oxidized by this electrode, allowing the urea concentration to be quantified. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-122783 Summary of the Invention [Problem to be solved by the invention]

[0005] The technology described in Patent Document 1 has room for reexamination from the viewpoint of ease of activation of an enzyme or coenzyme. Therefore, the present disclosure provides an electrode that is advantageous from the viewpoint of ease of activation of an enzyme or coenzyme. [Means for solving the problem]

[0006] The present disclosure provides: An electrode, a layer containing platinum black and forming a surface of the electrode; activating the enzyme or the coenzyme by donating or receiving electrons to or from at least one selected from the group consisting of an enzyme and a coenzyme; In an X-ray diffraction pattern of the surface of the electrode, the ratio of the maximum value of the diffraction intensity of the diffraction peak originating from the platinum (111) plane to the sum of the maximum values ​​of the diffraction intensity of the diffraction peaks originating from the platinum (111) plane, the platinum (200) plane, the platinum (220) plane, and the platinum (311) plane is 60% or more. An electrode is provided. [Effects of the Invention]

[0007] The electrodes of the present disclosure are prone to activating enzymes or coenzymes. [Brief explanation of the drawings]

[0008] [Figure 1A] FIG. 1A is a cross-sectional view showing an example of an electrode according to an embodiment. [Figure 1B] FIG. 1B is a cross-sectional view showing another example of an electrode according to an embodiment. [Figure 1C] FIG. 1C is a cross-sectional view showing yet another example of an electrode according to an embodiment. [Figure 1D] FIG. 1D is a cross-sectional view showing yet another example of an electrode according to an embodiment. [Figure 2] FIG. 2 is a diagram schematically illustrating an example of a reaction apparatus according to an embodiment. [Figure 3] FIG. 3 is a flowchart showing an example of a method for processing a target material according to an embodiment. [Figure 4A] FIG. 4A is a graph showing an X-ray diffraction (XRD) pattern of the surface of the electrode according to Example 10. [Figure 4B] FIG. 4B is a graph showing an X-ray diffraction (XRD) pattern of the surface of the electrode according to Example 10. [Figure 5] FIG. 5 is a graph showing the relationship between the reduction rate and the treatment time in Example 1, Example 9, and Comparative Example 1. [Figure 6] FIG. 6 is a graph showing the relationship between the ratio of the maximum value of the diffraction peaks originating from each crystal plane of platinum to the sum of the maximum values ​​of the diffraction peaks originating from specific crystal planes of platinum in the XRD pattern of the electrode surface and the reduction rate after applying a voltage for 1 hour. [Figure 7] FIG. 7 is a graph showing the relationship between the ratio of the maximum value of the diffraction peaks originating from each crystal plane of platinum to the sum of the maximum values ​​of the diffraction peaks originating from specific crystal planes of platinum in the XRD pattern of the electrode surface and the reduction rate after voltage application for 1 hour.

[0009] (Findings that formed the basis of this disclosure) When an enzyme such as an oxidoreductase and a coenzyme act on a target substance to cause an enzymatic reaction, the enzyme or coenzyme becomes inactive and the enzymatic reaction does not proceed any further. In vivo, the enzyme or coenzyme is continuously activated, and reactions involving the enzyme or coenzyme are repeated. It is also conceivable that outside of a living body, for example, electron transfer between an electrode and the enzyme or coenzyme can activate the enzyme or coenzyme, causing oxidation or reduction of the target substance. It is conceivable to use a platinum electrode as such an electrode.

[0010] According to the inventors' investigations, an electrode having a surface formed with a layer containing platinum black can activate an enzyme or coenzyme by donating and receiving electrons. Furthermore, the inventors conducted extensive research to determine whether an electrode capable of further enhancing the ease of enzyme or coenzyme activation could be realized. After extensive trial and error, the inventors newly discovered that, from the perspective of enhancing the ease of enzyme or coenzyme activation, it is important for the diffraction peaks derived from platinum in the XRD pattern of the electrode surface to have a specific relationship. Based on this new finding, the inventors have completed the electrode of the present disclosure.

[0011] (Embodiments of the present disclosure) Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step sequences shown in the following embodiments are merely examples and are not intended to limit the scope of the claims. Furthermore, among the components in the following embodiments, components that are not recited in the independent claims that represent the highest concepts are described as optional components. Furthermore, the drawings are not necessarily rigorous illustrations. In the drawings, substantially identical components are denoted by the same reference numerals, and redundant descriptions may be omitted or simplified. Furthermore, in this disclosure, terms indicating the relationship between elements, such as "parallel" and "perpendicular," terms indicating the shape of elements, such as "rectangle," and numerical values ​​do not only have strict meanings but also include a substantially equivalent range, for example, a difference of a few percent.

[0012] (Embodiment) Hereinafter, the embodiment will be specifically described with reference to FIGS. 1A to 3. FIG.

[0013] FIG. 1A is a cross-sectional view showing an example of an electrode according to an embodiment. The electrode 1a shown in FIG. 1A activates an enzyme or a coenzyme by donating and receiving electrons to at least one selected from the group consisting of an enzyme and a coenzyme. The electrode 1a includes a layer 14 containing platinum black and forming the surface 1s of the electrode 1a. In an X-ray diffraction (XRD) pattern of the surface 1s, a ratio P 111 is 60% or more. 111 is the ratio of the maximum value of the diffraction intensity of the diffraction peak originating from the platinum (111) plane to the sum of the maximum values ​​of the diffraction intensity of the diffraction peaks originating from the platinum (111) plane, the platinum (200) plane, the platinum (220) plane, and the platinum (311) plane. 111 is calculated by the following formula (1). In formula (1), I 111 is the maximum value of the diffraction intensity of the diffraction peak originating from the platinum (111) plane in the XRD pattern of the surface 1s. 200is the maximum value of the diffraction intensity of the diffraction peak originating from the platinum (200) plane in the XRD pattern of the surface 1s. 220 is the maximum value of the diffraction intensity of the diffraction peak originating from the platinum (220) plane in the XRD pattern of the surface 1s. 311 is the maximum value of the diffraction intensity of the diffraction peak originating from the platinum (311) plane in the XRD pattern of surface 1s. P 111 =I 111 / (I 111 +I 200 +I 220 +I 311 ) Formula (1)

[0014] The above ratio P in the XRD pattern of the surface 1s 111 is 60% or more, so the proportion P 111 The electrode 1a is more likely to activate the enzyme or coenzyme than when the electrode 1a has a solubility of less than 60%.

[0015] For example, the electrode 1a has a ratio P 111 can be 60% or more.

[0016] Percentage P 111 is preferably 65% ​​or more. In this case, the electrode 1a is more likely to activate the enzyme or coenzyme. 111 is more preferably 70% or more.

[0017] Percentage P 111 is, for example, 99% or less, and may be 95% or less.

[0018] Percentage P 111 The platinum content in layer 14 is not limited to a specific value, as long as it is 60% or more. Layer 14 contains, for example, 90% or more platinum by mass. With this configuration, electrode 1a is more likely to activate the enzyme or coenzyme.

[0019] The platinum content in layer 14 may be determined, for example, based on the XRD pattern of the surface 1s or by performing scanning electron microscope energy dispersive X-ray spectroscopy (SEM-EDX) measurements on layer 14.

[0020] The method for forming layer 14 is not limited to a specific method. For example, layer 14 may be formed by electrolytic plating. In this case, layer 14 is a plated layer. For example, a plating bath for forming layer 14 can be prepared by mixing a solution in which a predetermined amount of hexachloroplatinic acid (IV) hexahydrate (H2[PtCl6]·6H2O) is dissolved in ultrapure water, a solution in which a predetermined amount of lead (II) acetate trihydrate (Pb(CH3COO)2·3H2O) is dissolved in ultrapure water, and a predetermined amount of hydrochloric acid.

[0021] The electrode 1a comprises a layer 14 and the proportion P 111 The configuration of the electrode 1a is not limited to a specific configuration as long as the surface area is 60% or more. As shown in FIG. 1A, the electrode 1a further includes, for example, a predetermined substrate 1m. The substrate 1m is, for example, a conductive substrate containing a conductive material such as platinum, gold, titanium, glassy carbon, or indium tin oxide. The substrate 1m may include, for example, a glass substrate and a conductive film formed on the glass substrate. The conductive film contains, for example, at least one selected from the group consisting of platinum, gold, and titanium. For example, the substrate 1m is immersed in the above-mentioned plating bath and electrolytic plating is performed to form the layer 14, thereby obtaining the electrode 1a. The electrode 1a may include a portion containing platinum or platinum, or a portion containing a metal other than platinum, such as titanium, or a non-metallic material, such as carbon.

[0022] 1A, the electrode 1a includes a glass substrate 11, a titanium film 12, and a platinum layer 13. In the electrode 1a, the base material 1m has a layered structure in which the glass substrate 11, the titanium film 12, and the platinum layer 13 are layered in this order. The titanium film 12 is, for example, a vapor deposition film. The layer 14 is, for example, disposed in contact with the platinum layer 13.

[0023] 1A, for example, a lead 7a is attached to the electrode 1a. The lead 7a is a conductor for electrically connecting the outside of the electrode 1a to the electrode 1a. The lead 7a is electrically connected to, for example, the surface 1s.

[0024] FIG. 1B is a cross-sectional view showing another example of an electrode according to an embodiment. FIG. 1C is a cross-sectional view showing yet another example of an electrode according to an embodiment. FIG. 1D is a cross-sectional view showing yet another example of an electrode according to an embodiment. Electrode 1b shown in FIG. 1B, electrode 1c shown in FIG. 1C, and electrode 1d shown in FIG. 1D are configured similarly to electrode 1a except for portions that are particularly described. Components of electrodes 1b, 1c, and 1d that are the same as or correspond to components of electrode 1a are denoted by the same reference numerals, and detailed description thereof will be omitted. The above description of electrode 1a also applies to electrodes 1b, 1c, and 1d unless technically inconsistent.

[0025] 1B, the electrode 1b does not include a platinum layer 13, and the substrate 1m has a laminated structure in which a glass substrate 11 and a titanium film 12 are laminated. The layer 14 is disposed in contact with the titanium film 12, for example.

[0026] 1C, electrode 1c includes titanium substrate 15 and platinum layer 13. In electrode 1c, base material 1m has a laminated structure in which titanium substrate 15 and platinum layer 13 are laminated. Layer 14 is disposed in contact with platinum layer 13, for example.

[0027] As shown in FIG. 1D, electrode 1d includes a titanium substrate 15, and layer 14 is disposed on titanium substrate 15, for example.

[0028] For example, a reaction device can be provided that includes the above-described electrode. In this reaction device, at least one selected from the group consisting of an enzyme and a coenzyme is activated by the electrode, thereby causing oxidation or reduction of a target substance contained in a reaction system.

[0029] Fig. 2 is a diagram schematically illustrating an example of a reaction apparatus according to an embodiment. As shown in Fig. 2, the reaction apparatus 100 includes, for example, an electrode 1a. The reaction apparatus 100 may include an electrode 1b, an electrode 1c, or an electrode 1d instead of the electrode 1a.

[0030] The reaction device 100 further includes, for example, a reference electrode 2, a counter electrode 3, a cell 4, a lid 5, terminals 6a, 6b, and 6c, leads 7a, 7b, and 7c, a stirrer 8, a control device 30, and a stirrer 40. The electrode 1a, the reference electrode 2, the counter electrode 3, the cell 4, the lid 5, the terminals 6a, 6b, and 6c, and the leads 7a, 7b, and 7c form an electrochemical reactor 10, which is a three-electrode cell. In the electrochemical reactor 10, the electrode 1a functions as, for example, a working electrode. The electrochemical reactor 10 may also be configured as a two-electrode cell that includes the electrode 1a and the counter electrode 3 and omits the reference electrode 2.

[0031] The cell 4 has, for example, a first storage chamber 4a and a second storage chamber 4b therein. The electrode 1a and the reference electrode 2 are disposed in the first storage chamber 4a, and the counter electrode 3 is disposed in the second storage chamber 4b. The cell 4 has, for example, a connection part 4c. The connection part 4c connects the first storage chamber 4a and the second storage chamber 4b, and a separator 4s is disposed in the connection part 4c. The separator 4s separates the space on the first storage chamber 4a side of the connection part 4c from the space on the second storage chamber 4b side.

[0032] As described above, the first storage chamber 4a can accommodate a reaction system (source system) 9a containing a target substance. This allows the reaction system 9a to come into contact with the electrode 1a. The reaction system 9a contains, for example, at least one selected from the group consisting of an enzyme and a coenzyme. An example of the enzyme is an oxidoreductase. An example of the coenzyme is nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate. In this specification, reduced nicotinamide adenine dinucleotide is referred to as NADH, and oxidized nicotinamide adenine dinucleotide is referred to as NAD. +The reduced form of nicotinamide adenine dinucleotide phosphate is represented as NADPH, and the oxidized form of nicotinamide adenine dinucleotide phosphate is represented as NADP. + It is expressed as:

[0033] The second storage chamber 4b can store, for example, a liquid 9b, which can come into contact with the counter electrode 3. The liquid 9b is, for example, an electrolyte solution such as a phosphate buffer solution.

[0034] The separator 4s has, for example, ion conductivity and prevents the permeation of some of the components contained in the reaction system 9a and the liquid 9b. For example, the separator 4s prevents the permeation of the target substance, the oxide or reduced product of the target substance, the enzyme, and the coenzyme. The separator 4s has, for example, proton conductivity. The separator 4s contains, for example, a polymer having a perfluoro side chain containing a sulfonic acid group.

[0035] The surface of the counter electrode 3 includes, for example, a conductive material. Examples of conductive materials include carbon materials, conductive polymers, semiconductor materials, and metal materials. A conductive material is, for example, a material that does not decompose during oxidation of the conductive material. Examples of conductive materials include carbon materials, conductive polymers, semiconductor materials, and metal materials. Examples of carbon materials include carbon nanotubes, Ketjen Black (registered trademark), glassy carbon, graphene, fullerene, carbon fiber, carbon fabric, and carbon aerogel. Examples of conductive polymers include polyaniline, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene), poly(p-phenylene vinylene), polythiophene, and poly(p-phenylene sulfide). Examples of semiconductor materials include silicon, germanium, indium tin oxide (ITO), titanium oxide, copper oxide, and silver oxide. Examples of metallic materials include gold, platinum, silver, titanium, aluminum, tungsten, copper, iron, and palladium. The counter electrode 3 may be a platinum electrode.

[0036] In the reactor 100, for example, the electrode 1a functions as a cathode electrode, and the counter electrode 3 functions as an anode electrode. When a voltage is applied between the electrode 1a and the counter electrode 3, the potential of the electrode 1a is adjusted to a potential that can activate, for example, an enzyme or a coenzyme. The surface area of ​​the counter electrode 3 is, for example, larger than the surface area of ​​the electrode 1a. With this configuration, the enzyme or the coenzyme is more easily activated. In the reactor 100, the electrode 1a may function as an anode electrode, and the counter electrode 3 may function as a cathode electrode.

[0037] The reference electrode 2 does not react with the components contained in the reaction system 9a and is maintained at a specific potential. The reference electrode 2 is, for example, a silver / silver chloride electrode. The potential of the reference electrode 2 is maintained at, for example, a reference potential (0 V).

[0038] In the electrochemical reactor 10, the cell 4 is closed by, for example, a lid 5. Terminals 6a, 6b, and 6c are attached to the lid 5. Lead 7a extends from terminal 6a and electrically connects terminal 6a to electrode 1a. Lead 7b extends from terminal 6b and electrically connects terminal 6b to reference electrode 2. Lead 7c extends from terminal 6c and electrically connects terminal 6c to counter electrode 3. Terminals 6a, 6b, and 6c are electrically connected to a power source 20.

[0039] The power supply 20 applies a voltage between the electrode 1a and the counter electrode 3 in accordance with a control signal output from the control device 30, for example, and adjusts the potential difference between the electrode 1a and the reference electrode 2 to a predetermined value.

[0040] The control device 30 performs information processing to control the application of voltage by the power supply 20 and the movement of a motor (not shown) of the agitator 40. The control device 30 includes, for example, a memory that stores a program for controlling the application of voltage by the power supply 20 and the movement of the motor of the agitator 40, and an arithmetic device such as a processor that reads the program and performs predetermined calculations.

[0041] In the stirring device 40, the operation of the motor is controlled in accordance with a control signal output from the control device 30. This adjusts the rotation speed and rotation time of the stirring bars 8 arranged in each of the first storage chamber 4a and the second storage chamber 4b.

[0042] As shown in FIG. 2, the power supply 20 and the control device 30 may be separate entities, or the power supply 20 and the control device 30 may be integrally configured.

[0043] 3 is a flowchart showing an example of a method for treating a target substance according to an embodiment. The method for treating a target substance includes, for example, activating at least one selected from the group consisting of an enzyme and a coenzyme by an electrode 1a to cause oxidation or reduction of a target substance contained in a reaction system 9a. As described above, the electrode 1a easily activates the enzyme or coenzyme, and therefore the oxidation or reduction of the target substance can be promoted. The target substance is, for example, a substrate in an enzymatic reaction involving an enzyme.

[0044] The method for treating a target material can be carried out, for example, using the reaction apparatus 100 described above.

[0045] The reaction system 9a is not limited to a specific reaction system as long as it contains a target substance. The reaction system 9a may contain, for example, a food material. In this case, for example, the target substance contained in the food material can be oxidized or reduced, and this processing method can be used in the food industry.

[0046] As shown in FIG. 3, in step S101, a reaction system 9a is supplied to the reaction device 100. For example, the reaction system 9a is supplied to the first storage chamber 9a. Next, in step S102, a voltage is applied between the electrode 1a and the counter electrode 3. This activates the enzyme or coenzyme through electron exchange between the enzyme or coenzyme and the electrode 1a. Next, in step S103, the activated enzyme or coenzyme acts to oxidize or reduce the target substance contained in the reaction system 9a. The enzyme or coenzyme is continuously activated through electron exchange between the enzyme or coenzyme and the electrode 1a. Therefore, the target substance contained in the reaction system 9a is continuously oxidized or reduced. Next, in step S104, the application of the voltage between the electrode 1a and the counter electrode 3 is terminated. Next, in step S105, the oxide or reduction product of the target substance obtained in step S103 is recovered, completing the process.

[0047] (Addendum) From the above description, the following techniques are disclosed. (Technology 1) An electrode, a layer containing platinum black and forming a surface of the electrode; activating the enzyme or the coenzyme by donating or receiving electrons to or from at least one selected from the group consisting of an enzyme and a coenzyme; In an X-ray diffraction pattern of the surface of the electrode, the ratio of the maximum value of the diffraction intensity of the diffraction peak originating from the platinum (111) plane to the sum of the maximum values ​​of the diffraction intensity of the diffraction peaks originating from the platinum (111) plane, the platinum (200) plane, the platinum (220) plane, and the platinum (311) plane is 60% or more. electrode. (Technology 2) The proportion is 65% or more. Electrodes described in Technique 1. (Technology 3) The layer contains 90% or more platinum by mass, 3. The electrode according to claim 1 or 2. (Technology 4) The electrode according to any one of techniques 1 to 3 is provided, At least one selected from the group consisting of an enzyme and a coenzyme is activated by the electrode to cause oxidation or reduction of a target substance contained in a reaction system. Reactor. (Technology 5) The method includes activating at least one selected from the group consisting of an enzyme and a coenzyme by using the electrode according to any one of claims 1 to 3 to cause oxidation or reduction of a target substance contained in a reaction system. Methods for treating target materials. (Technology 6) The reaction system includes a food raw material. A method for treating a target substance according to technology 5. [Example]

[0048] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0049] Example 1 A substrate having a smooth, mirror-like platinum surface was immersed in a plating bath, and a platinum black layer was formed on the platinum layer by electroplating. The plating bath was prepared by mixing a predetermined amount of hexachloroplatinic acid (IV) hexahydrate (H2[PtCl6]·6H2O) in ultrapure water, a predetermined amount of lead acetate trihydrate (Pb(CH3COO)2·3H2O) in ultrapure water, and a predetermined amount of hydrochloric acid. The plating bath temperature was 25°C, and the plating time was 3 minutes. In this manner, an electrode according to Example 1 was obtained. The surface of the electrode according to Example 1 was black, and a layer containing platinum black formed the surface.

[0050] Example 2 An electrode according to Example 2 was obtained in the same manner as in Example 1, except that the temperature of the plating bath in the electrolytic plating was changed to 30°C.

[0051] Example 3 An electrode according to Example 3 was obtained in the same manner as in Example 1, except that the temperature of the plating bath in the electrolytic plating was changed to 40°C.

[0052] Example 4 An electrode according to Example 4 was obtained in the same manner as in Example 1, except that the temperature of the plating bath in the electrolytic plating was changed to 50°C.

[0053] Example 5 An electrode according to Example 5 was obtained in the same manner as in Example 1, except that the temperature of the plating bath in the electrolytic plating was changed to 60°C.

[0054] Example 6 An electrode according to Example 6 was obtained in the same manner as in Example 1, except that the plating time in the electrolytic plating was changed to 30 seconds.

[0055] Example 7 An electrode according to Example 7 was obtained in the same manner as in Example 1, except that the plating time in the electrolytic plating was changed to 1 minute.

[0056] Example 8 An electrode according to Example 8 was obtained in the same manner as in Example 1, except that the plating time in the electrolytic plating was changed to 2 minutes.

[0057] Example 9 An electrode according to Example 9 was obtained in the same manner as in Example 1, except that the temperature of the plating bath in the electrolytic plating was changed to 50° C. and the plating time was changed to 1 minute.

[0058] Example 10 An electrode according to Example 10 was obtained in the same manner as in Example 1, except that the temperature of the plating bath in the electrolytic plating was changed to 40° C. and the plating time was changed to 30 seconds.

[0059] (Comparative Example 1) A platinum electrode having a smooth, mirror-like surface was prepared as the electrode according to Comparative Example 1. No platinum black was formed on the surface of the electrode according to Comparative Example 1.

[0060] (Comparative Example 2) A commercially available platinum electrode having irregularities on its surface was prepared as the electrode according to Comparative Example 2.

[0061] (Comparative Example 3) A commercially available platinum black electrode was prepared as the electrode according to Comparative Example 3.

[0062] <X-ray Diffraction Measurement> Using a desktop X-ray diffractometer Aeris manufactured by Spectris Co., Ltd., XRD patterns by 2θ / θ scan of the surfaces of the electrodes according to each Example, Comparative Example 2, and Comparative Example 3 were obtained. Cu-Kα rays were used as the X-ray source. The wavelength of the Cu-Kα rays is 0.15418 nm. FIGS. 4A and 4B are graphs showing the XRD pattern of the surface of the electrode according to Example 10. In FIGS. 4A and 4B, the vertical axis represents the diffraction intensity, and the horizontal axis represents the diffraction angle 2θ. As shown in FIGS. 4A and 4B, in the XRD patterns of the surfaces of the electrodes according to each Example and each Comparative Example, diffraction peaks derived from the (111) plane, (200) plane, (220) plane, and (311) plane of platinum were confirmed. From the XRD patterns of the electrodes according to each Example and each Comparative Example, the maximum value I 111 , the maximum value I 200 , the maximum value I 220 , and the maximum value I 311 were calculated. I 111 is the maximum value of the diffraction intensity of the diffraction peak derived from the platinum (111) plane. I​​​​​​​​​​​​​​​​​

[0064] [Table 2]

[0065] <Measurement of coenzyme reduction rate> NAD in 2-(N-morpholino)ethanesulfonic acid monohydrate (MES) solution + The sample solution was prepared by dissolving NAD in this sample solution. + The concentration of was 1 mM. The pH of the MES solution was 6.5.

[0066] A three-electrode cell was constructed using the electrode according to each Example and Comparative Example as the working electrode, a Pt electrode as the counter electrode, and a silver / silver chloride electrode as the reference electrode. The sample solution described above was placed in this three-electrode cell, and a voltage was applied between the working electrode and the counter electrode so that the potential of the working electrode was −0.90 V while the working electrode was immersed in the sample solution. The voltage was applied for 6 hours. This is believed to have caused the reaction shown in the following formula to occur at the working electrode: NADH acts as a coenzyme in a given enzyme reaction and can promote the oxidation or reduction of a substrate. NAD + +H + +2e - → NADH

[0067] After a predetermined time had elapsed since the start of voltage application, a predetermined amount of measurement sample was taken from the sample solution, and the measurement sample was subjected to ultraviolet-visible absorbance measurement. The NADH concentration was calculated from the absorbance at a wavelength of 340 nm calculated by this measurement, and the reduction rate was calculated based on the following formula (2). Reduction rate [%] = NADH concentration of measurement sample / NADH concentration of sample solution + Initial concentration formula (2)

[0068] 5 is a graph showing the relationship between the reduction rate and the voltage application time in Example 1, Example 9, and Comparative Example 1. In FIG. 5, the vertical axis shows the reduction rate calculated by the above formula (2), and the horizontal axis shows the time during which the voltage was applied between the working electrode and the counter electrode in the three-electrode cell. According to FIG. 5, the electrodes according to Example 1 and Example 9 have a higher NAD than the electrode according to Comparative Example 1. + It is understood that this easily reduces the coenzyme and easily activates the coenzyme.

[0069] 6 and 7 are graphs showing the relationship between the ratio of the maximum value of the diffraction peaks originating from each platinum crystal plane to the sum of the maximum values ​​of the diffraction peaks originating from the above-mentioned platinum crystal planes in the XRD pattern of the electrode surface and the reduction rate after one hour of voltage application. In FIGS. 6 and 7, the bar graphs show the ratio of the maximum value of the diffraction peaks originating from each platinum crystal plane to the sum of the maximum values ​​of the diffraction peaks originating from the above-mentioned platinum crystal planes. In addition, the black dots plot show the reduction rate after one hour of voltage application calculated using the above formula (2). In FIG. 6, the plating temperature of the electroplating in Examples 1 to 5 is also shown, and in FIG. 7, the plating time of the electroplating in Examples 1 and 6 to 8 is also shown.

[0070] 6 and 7, the reduction rates in Examples 1 to 8 were higher than those in Comparative Examples 2 and 3. The ratio P 111 was 60% or more, whereas the percentage P 111 A comparison of Examples 1 to 8 with Comparative Examples 2 and 3 shows that the ratio P 111 By having a ratio of 60% or more, the reduction rate is high and NAD + It was suggested that coenzymes such as these are easily activated. [Industrial Applicability]

[0071] The electrode of the present disclosure can activate a coenzyme to promote the oxidation or reduction of a target substance, and can be used, for example, in the food industry. [Explanation of symbols]

[0072] 1a, 1b, 1c, 1d electrodes 1s surface 14 layers 100 Reactor

Claims

1. An electrode, a layer containing platinum black and forming a surface of the electrode; activating the enzyme or the coenzyme by donating or receiving electrons to or from at least one selected from the group consisting of an enzyme and a coenzyme; In an X-ray diffraction pattern of the surface of the electrode, the ratio of the maximum value of the diffraction intensity of the diffraction peak originating from the platinum (111) plane to the sum of the maximum values ​​of the diffraction intensity of the diffraction peaks originating from the platinum (111) plane, the platinum (200) plane, the platinum (220) plane, and the platinum (311) plane is 60% or more. electrode.

2. The proportion is 65% or more.

10. The electrode of claim 1.

3. The layer contains 90% or more platinum by mass.

10. The electrode of claim 1.

4. The electrode according to any one of claims 1 to 3, At least one selected from the group consisting of an enzyme and a coenzyme is activated by the electrode to cause oxidation or reduction of a target substance contained in a reaction system. Reactor.

5. The method includes activating at least one selected from the group consisting of an enzyme and a coenzyme by using the electrode according to any one of claims 1 to 3 to cause oxidation or reduction of a target substance contained in a reaction system. Methods for treating target materials.

6. The reaction system includes a food raw material. The method for treating a target substance according to claim 5 .

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