Electrode

Abstract

An electrode having a substrate, a silver / silver chloride electrode part, and a film containing particles of a two-dimensional material, the particles of the two-dimensional material including one or more layers, the one or more layers including a layer body represented by the following formula, and a modification or terminal T present on a surface of the layer body, mmXn (in the formula, M is at least one type of group 3, 4, 5, 6, and 7 metal and contains Ti, X is a carbon atom, a nitrogen atom, or a combination thereof, n is 1 to 4, and m is greater than n and 5 or less) (T is at least one type selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an electrode. BACKGROUND

[0002] In recent years, MXene has been attracting attention as a new material having electrical conductivity. MXene is one of so-called two-dimensional materials, and more specifically, is a two-dimensional material (layered material) having a morphology of one or more layers, as described later. In general, MXene has a morphology of particles (may include powder, flake, nanoplate, etc.) of the two-dimensional material (layered material). In Patent Literature 1, a living body electrode formed of a contact material containing the MXene is shown.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: International Publication No. 2019 / 055784 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In Patent Literature 1, MXene is used in a contact portion with a subject. However, in Patent Literature 1, no particular study is made on an electrode including a silver / silver chloride electrode portion, and it is considered that the low impedance of the electrode including the silver / silver chloride electrode portion is not sufficient. An object of the present disclosure is to provide an electrode including a silver / silver chloride electrode portion and exhibiting low impedance.

[0008] SOLUTION TO PROBLEM

[0009] According to one aspect of the present disclosure,

[0010] Provided is an electrode having: a base material, a silver / silver chloride electrode portion, and a film containing particles of a two-dimensional material including one or more layers,

[0011] The aforementioned one or more layers contain a layer main body represented by the following formula, and a modification or a terminal T present on the surface of the layer main body,

[0012] M m X n

[0013] (In the formula, M is at least one metal of Groups 3, 4, 5, 6, and 7 and contains Ti,

[0014] X is a carbon atom, a nitrogen atom, or a combination thereof,

[0015] n is 1 or more and 4 or less,

[0016] m is greater than n and 5 or less)

[0017] (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom).

[0018] Effects of the Invention

[0019] According to the present disclosure, a novel electrode with low impedance is provided, which has a substrate, a silver / silver chloride electrode portion, and a film containing particles of a prescribed two-dimensional material (also referred to as "MXene" in this specification). BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic cross-sectional view showing particles of a two-dimensional material (MXene) that can be used in one embodiment of the present disclosure, (a) shows a single-layer MXene particle, and (b) shows a multi-layer (example: two layers) MXene particle.

[0021] Figure 2 is a schematic cross-sectional view showing one embodiment of the electrode of the present disclosure.

[0022] Figure 3 is a schematic cross-sectional view showing another embodiment of the electrode of the present disclosure.

[0023] Figure 4 is a schematic cross-sectional view showing another embodiment of the electrode of the present disclosure.

[0024] Figure 5 is a schematic cross-sectional view showing another embodiment of the electrode of the present disclosure.

[0025] Figure 6 is a schematic cross-sectional view showing another embodiment of the electrode of the present disclosure.

[0026] Figure 7 is a measurement result of impedance in the example.

[0027] Figure 8 is a measurement result of other impedance in the example. DETAILED DESCRIPTION

[0028] Hereinafter, the electrode of the embodiment of the present invention will be described in detail, but the present invention is not limited to this embodiment.

[0029] (Electrode)

[0030] The electrode of the present embodiment has a substrate, a silver / silver chloride electrode portion, and a film containing particles of a two-dimensional material (hereinafter sometimes referred to as "MXene-containing film") that contains one or more layers. Thereby, an electrode that contains a silver / silver chloride electrode portion and exhibits low impedance can be provided.

[0031] Hereinafter, a film containing a particle including a two-dimensional material including one or more layers, which constitutes an electrode of the present embodiment, is described. The above-described two-dimensional material can be understood as a layered compound, and is also referred to as "M m X n T s ", s is an arbitrary number, and in the past, x or z has sometimes been used instead of s. Typically, n can be 1, 2, 3, or 4, but is not limited thereto.

[0032] In the above-described formula of MXene, M can be Ti alone, or can include Ti and also include one or more of Group 3, 4, 5, 6, 7 metals other than Ti. For example, Ti and at least one selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, and Mn can be included. In the case where M includes an element other than Ti, the element other than Ti is more preferably at least one selected from the group consisting of V, Cr, and Mo.

[0033] It is known that MXene is the above-described formula: M m X n is expressed as follows.

[0034] Ti2C, Ti2N, (Ti, V)2C, (Ti, Nb)2C, Ti3C2, Ti3N2, Ti3(CN), (Ti, V)3C2, (Ti2Nb)C2, (Ti2Ta)C2, (Ti2Mn)C2, (V2Ti)C2, (Cr2Ti)C2, (Mo2Ti)C2, (W2Ti)C2, Ti4N3, (Ti, Nb)4C3, (Ti2Nb2)C3, (Ti2Ta2)C3, (V2Ti2)C3, (Cr2Ti2)C3, (Mo2Ti2)C3, (W2Ti2)C3

[0035] Typically, in the above-described formula, M is titanium, or is titanium and vanadium, and X can be a carbon atom or a nitrogen atom. For example, the MAX phase that is a precursor of MXene is Ti3AlC2, and MXene is Ti3C2T s (in other words, M is Ti, X is C, n is 2, and m is 3).

[0036] Note that in the present embodiment, MXene can include A atoms remaining from its precursor MAX in a relatively small amount, for example, 10% by mass or less with respect to the original A atoms. The remaining amount of A atoms can be preferably 8% by mass or less, and more preferably 6% by mass or less. However, even if the remaining amount of A atoms exceeds 10% by mass, depending on the use, the use conditions, there are cases where there is no problem.

[0037] Hereinafter, the use of Figure 1 The MXene particle of the present embodiment is described.

[0038] The MXene particle of the present embodiment is Figure 1 a collection of the MXene 10a (single-layer MXene) schematically illustrated in (a) containing one layer, more specifically, a collection containing two or more MXenes 10a. The MXene 10a is more specifically a MXene layer 7a having: M m X n the layer body (M m X n layer) 1a, and a modification or a terminal T3a,5a present on the surface of the layer body 1a (more specifically, at least one of the two surfaces opposite to each other in each layer). Thus, the MXene layer 7a is also expressed as "M m X n T s ", and s is an arbitrary number.

[0039] In the MXene particle of the present embodiment, the MXene can be one layer or multiple layers. As the MXene of multiple layers (multi-layer MXene), as schematically illustrated in (b) of Figure 1 , two-layer MXenes 10b can be cited, but are not limited to these examples. Figure 1 1b, 3b, 5b, 7b in (b) of the above Figure 1 (a) are the same as 1a, 3a, 5a, 7a of the above (a). The two MXene layers adjacent to each other (for example, 7a and 7b) of the multi-layer MXene do not necessarily completely separate, and can partially contact. The aforementioned MXene 10a is the above multi-layer MXene 10b separated into one by one to exist as one layer, and sometimes the multi-layer MXene 10b remains without being separated, and is a mixture of the above single-layer MXene 10a and the multi-layer MXene 10b. Even in the case of containing the above multi-layer MXene, the multi-layer MXene is preferably a MXene with a small number of layers obtained by interlayer peeling treatment. The aforementioned "small number of layers" means, for example, that the number of layers of the MXene is 10 layers or less. Hereinafter, this "multi-layer MXene with a small number of layers" is sometimes referred to as "few-layer MXene". The thickness in the layer stacking direction of the few-layer MXene can be 15 nm or less, and further can be 10 nm or less. In addition, the single-layer MXene and the few-layer MXene are sometimes collectively referred to as "single-layer / few-layer MXene".

[0040] Most of the above MXene can be a single-layer / few-layer MXene. By most of the MXene being a single-layer / few-layer MXene, it is possible to make the specific surface area of the MXene larger than that of a multi-layer MXene, and as a result, in the case where the layered body is used for a use requiring conductivity, for example, it is possible to suppress the temporal degradation of conductivity. For example, a single-layer / few-layer MXene having a layer number of 10 layers or less and a thickness of 15 nm or less, preferably 10 nm or less, can be, for example, 80% by volume or more, further 90% by volume or more, and further 95% by volume or more, in terms of the proportion occupied in all the MXene. In addition, the volume of the single-layer MXene can also be larger than that of the few-layer MXene. The true density of these MXene does not greatly vary depending on the form, and thus it can also be said that the mass of the single-layer MXene is more than that of the few-layer MXene. In the case where these relationships are present, it is possible to increase the specific surface area of the MXene, and for example, in the case where it is used for a use requiring conductivity, it is possible to suppress the temporal degradation of conductivity. For example, the film can be formed only of the single-layer MXene.

[0041] Although not limited to the present embodiment, the thickness of each layer of the MXene (corresponding to the above MXene layers 7a, 7b) can be, for example, 1 nm or more and 30 μm or less, for example, 1 nm or more and 5 nm or less, and further 1 nm or more and 3 nm or less (mainly can vary depending on the number of M atom layers contained in each layer). The interlayer distance (or void size, Δd in (b) of the above) of each layered body of the multi-layer MXene that can be contained is, for example, 0.8 nm or more and 10 nm or less, particularly 0.8 nm or more and 5 nm or less, and more particularly about 1 nm, and the total number of layers can be 2 or more and 20,000 or less. Figure 1

[0042] The silver / silver chloride electrode portion contained in the electrode of the present embodiment is not particularly limited, and a silver / silver chloride electrode generally used in electrodes can be used.

[0043] The material of the substrate (also referred to as "electrode substrate") included in the electrode of the present embodiment is not particularly limited, and can be formed of any appropriate material. In addition, the shape of the substrate is not limited. The substrate can be, for example, a resin film, a metal foil, a printed circuit board, a mounting type electronic component, a metal pin, a metal wiring, a metal wire, or the like. For example, a substrate formed of a metal material, a resin, or the like suitable for a biological signal sensing electrode can be appropriately adopted. As the aforementioned metal material, resin, or the like, at least one material selected from the group consisting of gold, silver, copper, platinum, nickel, titanium, tin, iron, zinc, magnesium, aluminum, tungsten, molybdenum, and a conductive polymer can be mentioned.

[0044] ​This embodiment is not bound by any theory, but the reason why the electrode according to this embodiment, for example, shows lower impedance in a low frequency region is presumed as follows. First, silver / silver chloride undergoes a reversible reaction as shown in the following formula (1). Therefore, a silver / silver chloride electrode, for example, shows constant impedance at low frequencies (0.1 Hz to 1 Hz). In the low frequency region, since it becomes close to a state of direct current, overvoltage is applied. A reaction occurs when overvoltage is applied, and thus constant resistance corresponding to the reaction speed is shown.

[0045] AgCl + e - Ag + Cl - … (1)

[0046] On the other hand, MXene has a large capacity and low impedance at 1 Hz to 1000 Hz. As a reason why MXene has a large capacity, MXene has a layered structure can be given. MXene having a flake shape, for example, has a shape of about 3 pm in a planar direction and about 2 nm in thickness. A MXene electrode formed using this MXene has a multi-layer structure of a thousand-layer cake shape in which MXene flakes are overlapped. In addition, MXene has a property of adsorbing metal cations, and exhibits further increase in capacity. For example, when a MXene electrode is brought into contact with skin, moisture such as sweat of the skin penetrates into the multi-layer structure of the MXene electrode to a constant depth, and the penetrated portion functions as an electrode. Therefore, the effective electrode area that embodies the capacity is larger than that of a silver / silver chloride electrode of a flat plate, and the impedance becomes low. However, the MXene electrode does not show the reversible reaction of the above formula (1) of silver / silver chloride, and thus has a problem that the impedance becomes high in a low frequency region of 0.1 Hz to 1 Hz.

[0047] The electrode of the present embodiment is different from the MXene electrode described above, and has a silver / silver chloride electrode portion and a MXene-containing film. The silver / silver chloride electrode portion and the MXene-containing film can be separate, and the MXene-containing film can also function as the silver / silver chloride electrode portion. Hereinafter, first, a description will be given of a case where the silver / silver chloride electrode portion and the MXene-containing film are separate. As one embodiment of the electrode of the present embodiment, for example, an electrode in which a silver / silver chloride electrode portion is provided on at least a part of the surface of a substrate, and a MXene-containing film is provided on at least a part of the surface of the silver / silver chloride electrode portion exposed to the outside environment can be given. In this case, in a low frequency region of 0.1 Hz to 1 Hz, an electrolyte (electrolytic substance) such as moisture of the skin penetrates into the MXene-containing film described above, reaches the silver / silver chloride electrode portion, and a reversible reaction such as the one represented by the above formula (1) occurs, and the impedance is suppressed to be low. On the other hand, in a region of a frequency higher than 1 Hz, the above effect based on the MXene-containing film is exhibited, and the impedance is suppressed to be low. In addition, as another embodiment of the electrode of the present embodiment, for example, an electrode in which a MXene-containing film is provided on at least a part of the surface of a substrate, and a silver / silver chloride electrode portion is provided on at least a part of the surface of the MXene-containing film exposed to the outside environment can be given. Even in this case, it is possible to suppress the impedance to be low in a wide frequency range including a low frequency region. As one of the reasons therefor, it is considered that in a low frequency region of 0.1 Hz to 1 Hz, a reversible reaction such as the one represented by the above formula (1) occurs, and the impedance is suppressed to be low. On the other hand, it is considered that in a region of a frequency higher than 1 Hz, an electrolyte (electrolytic substance) such as moisture of the skin penetrates from a gap such as a defect that can exist in the silver chloride portion of the silver / silver chloride electrode portion, reaches the MXene-containing film, the above effect based on the MXene-containing film is exhibited, and the impedance is suppressed to be low.

[0048] The specific mode of the MXene-containing film in the electrode of the present embodiment is not limited. The MXene-containing film can be given from a solid state to a soft state having flexibility. In the case where the MXene-containing film has a sheet-like form, the thickness thereof can be measured, for example, by measurement using a micrometer, cross-sectional observation using a scanning electron microscope (SEM), a microscope, or a laser microscope, or the like.

[0049] The thickness of the MXene-containing film in the electrode of the present embodiment is preferably 1 nm or more and 5 μm or less. By being in the above range, the impedance can be further reduced. By making the thickness of the MXene-containing film 5 μm or less, the effects of, for example, the electrolyte penetrating into the MXene-containing film can be more effectively exhibited. The thickness of the MXene-containing film may, for example, be 1.0 μm or less, further 0.8 μm or less, further 0.5 μm or less. On the other hand, in order to sufficiently exhibit the effect of the conductivity based on the MXene-containing film, the thickness of the MXene-containing film is preferably 1 nm or more. The thickness of the MXene-containing film is more preferably 10 nm or more.

[0050] The aforementioned film of particles containing a two-dimensional material (MXene-containing film) can contain a polymer. By containing the aforementioned polymer, the adhesion strength to an electrode substrate or the like can be improved.

[0051] The aforementioned polymer is preferably a water-soluble polymer. By containing the aforementioned water-soluble polymer, the adhesion strength to an electrode substrate can be further improved. As the aforementioned water-soluble polymer, for example, a water-soluble conductive polymer belonging to a thiophene-based polymer, a MPC polymer in which a monomer having a phosphorylcholine group is a main component, an acrylic polymer, a polyurethane, a polyethylene glycol, a carboxymethyl cellulose (CMC), an alginate polymer, a polyether, a polyvinyl alcohol, a water-soluble polyester, a dicarboxylated polysaccharide, or the like can be given. As the water-soluble polymer, one or more selected from the group consisting of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS), Lipidure (registered trademark) A, Lipidure (registered trademark) PMB, a polyurethane, a polyacrylic acid, a sodium polyacrylate, and a cation-modified PVA can be given. By containing one or more of these water-soluble polymers, the adhesion strength to an electrode substrate can be further improved.

[0052] In the case where the aforementioned film of particles containing a two-dimensional material contains a polymer, the proportion of the aforementioned particles of a two-dimensional material may, for example, be 0.5 mass% or more and 50 mass% or less. By making the proportion of the aforementioned particles of a two-dimensional material 0.5 mass% or more, the signal can be detected with high sensitivity. The proportion of the aforementioned particles of a two-dimensional material is more preferably 1.0 mass% or more. From the viewpoint of ensuring higher flexibility of the composite material, the aforementioned proportion is preferably 50 mass% or less, more preferably 40 mass% or less. The proportion of the aforementioned particles of a two-dimensional material refers to the proportion in the film. The MXene-containing film can sometimes contain an additive such as a colorant, an antioxidant, and the like, in which case the aforementioned proportion of the particles of a two-dimensional material refers to the proportion (mass%) in the film containing the aforementioned additive.

[0053] The electrode in this embodiment can preferably be used as a biological signal sensing electrode, such as an electrode that can detect biological information such as electrical signals from the brain and heart with high sensitivity, for example, for measuring EEG (brain waves), ECG (electrocardiogram), etc.

[0054] The frequency range of the electrode in this embodiment is not particularly limited. The electrode of this embodiment exhibits excellent conductivity (low impedance) especially when used in the lower frequency region (below 1000 Hz). For example, the electrode of this embodiment can be used in frequency ranges below 500 Hz, further below 300 Hz, further below 200 Hz, and further below 150 Hz. The frequency range can be, for example, 0.05 Hz or higher, such as 0.1 Hz or higher. In particular, it can be used in the frequency range of 0.1 to 150 Hz. As a way to enable use in the aforementioned lower frequency region, examples include the measurement of brain waves, electrocardiograms, etc., and especially the measurement of brain waves. Therefore, the electrode of this embodiment is preferably used for the aforementioned measurement of brain waves, electrocardiograms, etc.

[0055] The electrode of this embodiment only needs to have a substrate, a silver / silver chloride electrode portion, and an MXene-containing film. As one type of electrode in this embodiment, an electrode in which at least a portion of the surface of the substrate is provided with a silver / silver chloride electrode portion, and at least a portion of the surface of the silver / silver chloride electrode portion exposed to the external environment is provided with an MXene-containing film. For example... Figure 2 As shown in the schematic cross-sectional view, an example is an electrode 20a having a silver / silver chloride electrode portion 23 disposed on the surface of an electrode substrate 21, and further having an MXene film 25 disposed on the surface of the silver / silver chloride electrode portion 23. Examples of electrodes include those described above. Figure 2 As shown, the aforementioned substrate has a front end and a long side direction, and the aforementioned silver / silver chloride electrode portion is disposed on the surface of the front end and side of the substrate, and the aforementioned MXene-containing film is disposed on about 50% or more of the surface of the silver / silver chloride electrode portion exposed to the external environment.

[0056] Another type of electrode according to this embodiment can be an electrode in which at least a portion of an MXene-containing film is disposed on the surface of a substrate, and a silver / silver chloride electrode portion is disposed on at least a portion of the MXene-containing film surface exposed to the external environment. As an example, an electrode such as... Figure 3 As shown in the schematic cross-sectional view, an electrode 20b is formed by disposing of an MXene film 25 on the surface of an electrode substrate 21, and then a silver / silver chloride electrode portion 23 is disposed on the surface of the MXene film 25. Examples of electrodes include those described above. Figure 3As shown, the aforementioned substrate has a front end and a long side direction, and the aforementioned MXene-containing film is disposed on the surface of the substrate including the front end, and the aforementioned silver / silver chloride electrode portion is disposed on about 50% or more of the surface of the MXene-containing film exposed to the external environment.

[0057] As mentioned above Figure 2 A variation of this can be illustrated by the following electrode 20c, such as... Figure 4 As shown in the schematic cross-sectional view, the proportion of the silver / silver chloride electrode portion 23 disposed on the surface of the electrode substrate 21 is smaller than that described above. Figure 2 Examples of electrodes include those described above. Figure 4 As shown, the aforementioned substrate has a front end and a long side direction. A silver / silver chloride electrode portion is disposed on the surface of the substrate, including the front end, and the aforementioned MXene-containing film (a film containing particles of two-dimensional material) is disposed on the entire surface of the silver / silver chloride electrode portion exposed to the external environment. The electrode of this embodiment can be exemplified as described above. Figure 4 As shown, a substrate has a probe, for example, with a front end and a long side direction. A silver / silver chloride electrode portion 23 is formed only in the front end region 27 of the probe, and an MXene-containing film 25 is configured to cover the entire surface of the silver / silver chloride electrode portion 23 exposed to the external environment. In this configuration, for example, when used as a biosensing electrode, the surface in contact with the skin is an MXene-containing film, thus providing excellent biocompatibility. Furthermore, it is believed that... Figure 4 As shown, by suppressing the proportion of silver / silver chloride electrode portion in the electrode and covering the silver / silver chloride electrode portion with an MXene-containing film, the degradation of the silver / silver chloride electrode portion can be suppressed, and the electrode life can be extended.

[0058] In the electrodes of this embodiment, as described above... Figure 2 As shown, preferably, the silver / silver chloride electrode portion is in direct contact with the MXene-containing film in at least a portion.

[0059] Another type of electrode in this embodiment can be exemplified by a brush-shaped electrode having a support and a plurality of styluses for contacting the object being measured. At least one of the styluses has a substrate, a silver / silver chloride electrode portion, and a film containing particles of a two-dimensional material, the particles comprising one or more layers. The silver / silver chloride electrode portion is disposed on at least a portion of the surface of the substrate, including the tip of the styluse, and the MXene-containing film is disposed on at least a portion of the surface of the silver / silver chloride electrode portion exposed to the external environment. For example, ... Figure 5 As shown, a brush-shaped electrode 30 can be provided, in which multiple styluses 33 are connected to a support 31. For example, multiple styluses 33 can each perform the aforementioned actions. Figures 2-4 Any of the methods mentioned above.

[0060] Next, a mode in which a film containing MXene serves as a silver / silver chloride electrode portion will be described. In this mode, the film of the aforementioned particles containing a two-dimensional material (MXene particles) also contains silver / silver chloride, and is a silver / silver chloride electrode portion. The aforementioned film can be a film in which silver / silver chloride and MXene are dispersed in each other (hereinafter sometimes referred to as "silver / silver chloride-MXene dispersed film"). By making a silver / silver chloride-MXene dispersed film, it is possible to reduce the impedance in a wide frequency range compared to the case where silver / silver chloride is alone. Silver has high electrical conductivity, but silver / silver chloride does not have electrical conductivity. The electrical conductivity of MXene is one to two orders of magnitude lower than that of silver, but the impedance is also lower than that of silver / silver chloride. Therefore, the reason why the impedance of the dispersion of MXene and silver / silver chloride is lower than that of MXene alone and that of silver / silver chloride alone is considered to be that the low electrical conductivity of MXene is improved by the silver contained in silver / silver chloride. This effect is obtained by dispersing silver / silver chloride and MXene. In order to further reduce the impedance, the volume ratio of MXene in the dispersed film is preferably 25% or more by volume, more preferably 30% or more by volume, and is preferably 75% or less by volume, more preferably 70% or less by volume.

[0061] In the silver / silver chloride-MXene dispersed film, as a third component other than silver / silver chloride and MXene, for example, a binder, an organic dispersing medium molecule, an inorganic material as a thickening agent, or the like that can be contained in a silver / silver chloride paste used in the production of the silver / silver chloride-MXene dispersed film can be given. The volume ratio of the third component in the silver / silver chloride-MXene dispersed film can be, for example, 5% or less by volume, and further 1% or less by volume.

[0062] As one mode of the electrode including the aforementioned silver / silver chloride-MXene dispersed film, for example, a mode in which the silver / silver chloride-MXene dispersed film is provided on the surface of an electrode substrate can be given. Figure 6 As shown in the schematic cross-sectional view, the electrode 40 in which the silver / silver chloride-MXene dispersed film 43 is provided on the surface of the electrode substrate 41 is given.

[0063] In addition, as another mode of the electrode of the present embodiment, an electrode in which the electrode is in the shape of a brush having a support body and a plurality of styluses for contacting the object to be measured, at least one of the plurality of styluses has a substrate and the aforementioned silver / silver chloride-MXene dispersed film, and the silver / silver chloride-MXene dispersed film is provided on at least a part of the surface of the substrate at a portion including the tip end of the stylus can be given. For example, as shown in the aforementioned Figure 5 As shown in the aforementioned Figure 6 , a mode in which the plurality of styluses 33 are connected to the support body 31 to form the electrode 30 in the shape of a brush can be given.

[0064] The above Figures 2-6 The electrode substrate, silver / silver chloride electrode portion, MXene-containing film, silver / silver chloride-MXene dispersion film, and the like in the drawings are illustrative for ease of understanding, and the shape, film thickness, and the like of each of these, the ratio of the dimensions to each other, the number of the tips, the interval, the arrangement, and the like can be different from those of the actual electrode. In addition, the above drawings illustrate the electrode of the present embodiment, but the electrode of the present embodiment is not limited to the mode illustrated in the above drawings. For example, the cross section of the tips of the brush-shaped electrode can not only be the rectangular shape illustrated in the above drawings, but also a sharp triangular shape, a sharp trapezoidal shape, and the like. In addition, the tip end of the tips can be a flat surface or a convex curved surface, and the like.

[0065] (Method for manufacturing electrode)

[0066] The electrode of the present embodiment can be manufactured, for example, by the method described below. However, the method for manufacturing the electrode of the present embodiment is not limited to this embodiment.

[0067] First, the method for manufacturing the electrode in which the silver / silver chloride electrode portion and the MXene-containing film are formed separately will be described.

[0068] As an example of the method for manufacturing the electrode of the present embodiment, the following procedure can be given.

[0069] In the procedure (a), particles of a two-dimensional material are prepared, the particles of the two-dimensional material including one or more layers,

[0070] The aforementioned one or more layers include a layer main body represented by the following formula and a modification or a terminal T present on the surface of the layer main body,

[0071] M m X n

[0072] (In the formula, M is at least one metal of Groups 3, 4, 5, 6, and 7 and includes Ti,

[0073] X is a carbon atom, a nitrogen atom, or a combination thereof,

[0074] n is 1 or more and 4 or less,

[0075] m is greater than n and 5 or less

[0076] (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom);

[0077] In the procedure (b1), a film containing the particles of the two-dimensional material is formed on at least a part of the surface of the silver / silver chloride electrode portion formed on the surface of the substrate (the surface exposed to the external environment); or,

[0078] Process (b2) forms a film containing the particles of the two-dimensional material on at least a part of the surface of the substrate using the particles of the two-dimensional material described above, and then forms a silver / silver chloride electrode portion on at least a part of the surface (surface exposed to the outside environment) of the film containing the particles of the two-dimensional material. Each process will be described below.

[0079] • Process (a)

[0080] First, a prescribed precursor is prepared. The prescribed precursor that can be used in the present embodiment is a MAX phase that is a precursor of MXene, which is represented by the following formula:

[0081] M m AX n

[0082] (In the formula, M is at least one metal of Groups 3, 4, 5, 6, and 7 and contains Ti,

[0083] X is a carbon atom, a nitrogen atom, or a combination thereof,

[0084] A is at least one element of Groups 12, 13, 14, 15, and 16,

[0085] n is 1 or more and 4 or less,

[0086] m is greater than n and 5 or less).

[0087] The above M, X, n, and m are as described in MXene. A is at least one element of Groups 12, 13, 14, 15, and 16, and is typically an A group element, and is typically a Group IIIA and Group IVA, and more specifically, can contain at least one selected from the group consisting of Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, S, and Cd, and is preferably Al.

[0088] The MAX phase has a crystal structure in which a layer composed of A atoms is located between two layers represented by M m X n (In the formula, M is at least one metal of Groups 3, 4, 5, 6, and 7 and contains Ti, m X n (In the formula, M is at least one metal of Groups 3, 4, 5, 6, and 7 and contains Ti,

[0089] The MAX phase described above can be produced by a known method. For example, TiC powder, Ti powder, and Al powder are mixed with a ball mill, and the resulting mixed powder is fired under an Ar atmosphere to obtain a fired body (bulk MAX phase). Thereafter, the resulting fired body is pulverized with an end mill, and a powdered MAX phase for the next step can be obtained.

[0090] By selectively etching (removing and delaminating as the case can be) A atoms (and part of M atoms as the case can be) from the MAX phase, thereby removing the A atom layer (and part of the M atom layer as the case can be), the hydroxyl group, fluorine atom, chlorine atom, oxygen atom, and hydrogen atom, etc. present in the etching solution (typically an aqueous solution containing fluorine acid, but not limited thereto) modify the surface of the exposed M m X n layer, and cap the surface.

[0091] The etching described above can be performed using an etching solution containing F - , for example, a method using a mixed solution of lithium fluoride and hydrochloric acid, a method using hydrofluoric acid, etc. The metal compound containing monovalent metal ions contained in the etching solution can be subjected to intercalation treatment of monovalent metal ions simultaneously with the etching described above. As the metal compound containing monovalent metal ions, for example, those used in the intercalation treatment described below can be mentioned. The content of the metal compound containing monovalent metal ions in the etching solution is preferably 0.001 mass% or more. The content described above is more preferably 0.01 mass% or more, and further preferably 0.1 mass% or more. On the other hand, from the viewpoint of dispersibility in solution, the content of the metal compound containing monovalent metal ions in the etching solution is preferably 10 mass% or less, and more preferably 1 mass% or less.

[0092] After the etching described above, the delamination of MXene (delamination, separation of a multilayer MXene into a single layer MXene) can be promoted as appropriate by any suitable post-treatment (for example, ultrasonic treatment, hand shaking, or an automatic shaker, etc.). Note that the ultrasonic treatment can damage the MXene due to excessive shear force, and therefore in the case where a two-dimensional MXene (preferably a single layer MXene) having a larger aspect ratio is desired, it is preferable to impart an appropriate shear force by hand shaking or an automatic shaker, etc.

[0093] For the delamination of the MXene described above, the intercalation treatment and delamination described below can be performed.

[0094] (Intercalation treatment)

[0095] For example, intercalation treatment of monovalent metal ions can be performed, which includes a step of mixing the etching treatment product obtained by the aforementioned etching treatment with a metal compound containing monovalent metal ions. As the monovalent metal ions constituting the metal compound containing monovalent metal ions, alkali metal ions such as lithium ions, sodium ions, and potassium ions, copper ions, silver ions, gold ions, and the like can be given. As the aforementioned metal compound containing monovalent metal ions, ionic compounds in which the aforementioned metal ions are bonded to cations can be given. For example, iodides, phosphates, sulfide salts including sulfate salts, nitrate salts, acetate salts, carboxylate salts of the aforementioned metal ions can be given. As the aforementioned monovalent metal ions, lithium ions are preferred, and as the metal compound containing monovalent metal ions, metal compounds containing lithium ions are preferred, and ionic compounds of lithium ions are more preferred, and one or more of iodides, phosphates, sulfide salts of lithium ions are further preferred. It is considered that if lithium ions are used as metal ions, water hydrated with lithium ions has the most negative dielectric constant, and thus becomes easy to monolayer.

[0096] The content ratio of the metal compound containing monovalent metal ions in the compounding material for intercalation treatment of monovalent metal ions is preferably 0.001% by mass or more. The content ratio is more preferably 0.01% by mass or more, and further preferably 0.1% by mass or more. On the other hand, from the viewpoint of dispersibility in a solution, the content ratio of the metal compound containing monovalent metal ions is preferably 10% by mass or less, and more preferably 1% by mass or less.

[0097] (Layer separation)

[0098] Layer separation using the intercalation treatment product obtained by intercalation can be given. For example, layer separation including a step of centrifuging the intercalation treatment product, discarding the supernatant, and then washing the remaining precipitate with a dispersion medium such as water can be given. The conditions for layer separation treatment are not particularly limited. The dispersion medium used in layer separation is also not particularly limited, and for example, one or more of a polar organic dispersion medium and an aqueous dispersion medium can be used. The operation of adding one or more of the polar organic dispersion medium and the aqueous dispersion medium, stirring, centrifuging, and recovering the supernatant is repeated one or more times, preferably two or more times and ten or fewer times, to obtain a supernatant containing monolayer / few-layer MXene as a layer separation treatment product. Alternatively, the supernatant can be centrifuged, the supernatant after centrifugation can be discarded, and a clay containing monolayer / few-layer MXene can be obtained as a layer separation treatment product.

[0099] • Step (b1, b2)

[0100] Step (b1) forms a film containing particles of the two-dimensional material on at least a part of the surface of the silver / silver chloride electrode portion formed on the surface of the substrate (the surface exposed to the external environment) using particles of the aforementioned two-dimensional material; or,

[0101] The process (b2) forms a film containing the particles of the two-dimensional material on at least a part of the surface of the substrate, and then forms the silver / silver chloride electrode portion on at least a part of the surface of the film containing the particles of the two-dimensional material (the surface exposed to the outside environment).

[0102] In either case of the process (bl) or the process (b2), the silver / silver chloride electrode portion can be formed by the same method as the formation method of a general silver / silver chloride electrode. Hereinafter, the method for forming the film containing the particles of the two-dimensional material (the MXene-containing film) on at least a part of the surface of the silver / silver chloride electrode portion formed on the surface of the substrate (the process (bl)) or at least a part of the surface of the substrate (the process (b2)) using the particles of the two-dimensional material described above will be described.

[0103] In the formation of the MXene-containing film, a dispersion of the particles of the two-dimensional material (MXene particles) such as an MXene slurry obtained by diluting the above-described clay medium containing monolayer / few-layer MXene with a medium liquid can be used. The dispersion can be a suspension. The method for forming the MXene-containing film using the dispersion of the MXene particles is not particularly limited. The dispersion of the MXene particles is directly or appropriately adjusted (for example, diluted with a medium liquid or a binder is added), and then, in the case of the process (bl), the dispersion is supplied to at least a part of the surface of the silver / silver chloride electrode portion, and in the case of the process (b2), the dispersion is supplied to at least a part of the surface of the substrate. As an example of the method for supplying, a coating method can be given. As the coating method, for example, a method using spraying with a nozzle such as a single-fluid nozzle, a two-fluid nozzle, or an airbrush (a method using a spray coater), slit coating using a bench coater, a comma coater, or a rod coater, screen printing, metal mask printing, spin coating, dip coating, dropwise addition, or the like can be given. As the above-described medium liquid, an aqueous medium liquid or an organic medium liquid can be given. The medium liquid constituting the dispersion of the MXene particles is typically water, and depending on the case, in addition to water, other liquid substances can be contained in a relatively small amount (for example, 30% by mass or less, preferably 20% by mass or less, based on the whole). As the organic medium liquid, for example, N-methylpyrrolidone, N-methylformamide, N,N-dimethylformamide, ethanol, methanol, dimethyl sulfoxide, ethylene glycol, acetic acid, or the like can be given.

[0104] In the case where the MXene-containing film is formed of a composite material containing a polymer, as exemplified below, the above-described layered material can be mixed with a polymer.

[0105] For example, a MXene aqueous dispersion in which the above-described MXene particles (particles of a two-dimensional material) are present in a dispersion medium, or a dispersion of MXene and an organic dispersion medium, or a mixture of MXene powder and a polymer can be given. The dispersion medium of the above-described MXene aqueous dispersion is typically water, and depending on the case, other liquid substances can be contained in a relatively small amount (for example, 30% by mass or less, preferably 20% by mass or less, based on the whole) in addition to water.

[0106] The stirring of the above-described MXene particles and the polymer can be performed using a dispersing device such as a homogenizer, a propeller stirrer, a thin-film rotary stirrer, a planetary stirrer, a mechanical shaker, a vortex stirrer, or the like.

[0107] In the case of the process (bl), a slurry as a mixture of the above-described MXene particles and the polymer can be given as an example of a material to be applied to at least a part of the surface (a surface exposed to the outside environment) of the silver / silver chloride electrode portion formed on the surface of a substrate (for example, a substrate). In addition, in the case of the process (b2), application to at least a part of the surface of a substrate (for example, a substrate) can be given as an example. The application method is not limited, and for example, a method in which spraying is performed using a single-fluid nozzle, a two-fluid nozzle, an airbrush, or the like; slit coating using a bench coater, a comma coater, a rod coater; screen printing, metal mask printing, or the like; a coating method based on spin coating, immersion, dropwise addition can be given.

[0108] The formation and drying of the MXene-containing film can be appropriately repeated until a desired thickness of the MXene-containing film is obtained, with or without the polymer. For example, a combination of spraying and drying can be repeatedly performed several times. The liquid component of the liquid medium from the slurry can remain in the MXene-containing film, or can be substantially absent.

[0109] The drying can be performed under mild conditions such as natural drying (typically, in an air atmosphere at normal temperature and pressure), air drying (blowing of air), or the like, or can be performed under relatively aggressive conditions such as hot air drying (blowing of heated air), heating drying, and / or vacuum drying. In the present embodiment, "drying" refers to an operation for removing the medium liquid that can be present in the precursor film obtained by the aforementioned application. The aforementioned drying can be performed, for example, using a normal-pressure oven or a vacuum oven at a temperature of 400°C or lower. For example, an operation in which the drying is performed at 30°C or higher and 200°C or lower, for 30 minutes or longer and 24 hours or less can be given.

[0110] Next, a method for manufacturing an electrode having a silver / silver chloride-MXene dispersion film, which is a silver / silver chloride electrode portion including a MXene film, will be described. MXene particles (particles of a two-dimensional material) can be manufactured by the aforementioned method. A MXene aqueous dispersion in which the obtained MXene particles (particles of a two-dimensional material) are present in a dispersion medium, or a dispersion of MXene and an organic dispersion medium, or a mixture of MXene powder and silver / silver chloride can be mentioned. The dispersion medium of the aforementioned MXene aqueous dispersion is typically water, and depending on the case, other liquid substances can be contained in a relatively small amount (for example, 30% by mass or less, preferably 20% by mass or less, based on the whole) in addition to water. The silver / silver chloride can be, for example, a paste.

[0111] The stirring of the aforementioned MXene particles and silver / silver chloride can be performed using a dispersing device such as a homogenizer, a propeller stirrer, a thin-film rotary stirrer, a planetary stirrer, a mechanical shaker, a vortex stirrer, and the like.

[0112] A slurry that is a mixture of the aforementioned MXene particles and silver / silver chloride can be applied to at least a part of the surface of a substrate (for example, a substrate). The application method is not limited, and for example, a method in which spraying is performed using a nozzle such as a single-fluid nozzle, a two-fluid nozzle, an airbrush, slit coating using a bench coater, a comma coater, a rod coater, screen printing, metal mask printing, and the like, and a coating method based on spin coating, dipping, dropwise addition can be mentioned.

[0113] The formation and drying of the silver / silver chloride-MXene dispersion film can be appropriately repeated until the desired thickness of the silver / silver chloride-MXene dispersion film is obtained. For example, a combination of spraying and drying can be repeated several times. The silver / silver chloride-MXene dispersion film can have a liquid component of a liquid medium from the slurry remaining therein, or can be substantially free of the same.

[0114] Drying can be performed under mild conditions such as natural drying (typically, in an air atmosphere at normal temperature and pressure), air drying (blowing of air), or can be performed under relatively aggressive conditions such as hot air drying (blowing of heated air), heating drying, and / or vacuum drying. In the present embodiment, "drying" refers to an operation for removing a medium liquid that can be present in a precursor film obtained by the aforementioned application. The aforementioned drying can be performed, for example, using a normal-pressure oven or a vacuum oven at a temperature of 400°C or lower. For example, an operation in which drying is performed at 30°C or higher and 200°C or lower, for 30 minutes or longer and 24 hours or less can be mentioned.

[0115] The electrode of the present disclosure and the method for manufacturing the same are described in detail above, but various changes can be made. Note that it should be noted that the electrode of the present disclosure can also be manufactured by a method other than the manufacturing method in the above-described embodiment.

[0116] EMBODIMENT

[0117] The present application will be described more specifically below by citing examples. The present application is not limited by the following examples, and can be appropriately changed and implemented within a range that can meet the main idea described above and below, and these are all included in the scope of the present application.

[0118] [Example 1]

[0119] 1. Preparation of particles of two-dimensional material

[0120] The following (1) preparation of precursor (MAX), (2) etching of precursor, (3) cleaning after etching, (4) intercalation of Li, and (5) delamination are sequentially performed to first obtain particles of two-dimensional material (MXene particles).

[0121] (1) Preparation of precursor (MAX)

[0122] TiC powder, Ti powder, and Al powder (all manufactured by Takasago Pure Chemical Industries Co., Ltd.) were put into a ball mill equipped with zirconia balls at a molar ratio of 2:1:1 and mixed for 24 hours. The obtained mixed powder was fired at 1350°C for 2 hours under an Ar atmosphere. The fired body (bulk MAX) thus obtained was pulverized with an end mill to a maximum size of 40 μm or less. Thus, Ti3AlC2 particles as a precursor (powdered MAX) were obtained.

[0123] (2) Etching of precursor (MAX)

[0124] Using the Ti3AlC2 particles (powder) prepared by the above-described method, etching was performed under the following etching conditions to obtain a solid-liquid mixture (slurry) containing a solid component derived from the Ti3AlC2 powder.

[0125] (Etching conditions)

[0126] • Precursor: Ti3AlC2 (through a sieve with a mesh size of 45 μm)

[0127] • Etching solution composition: 49% HF 6 mL,

[0128] H2O 18 mL

[0129] HCl (12M) 36 mL

[0130] • Precursor input amount: 3.0 g

[0131] • Etching container: 100 mL jar

[0132] • Etching temperature: 35°C

[0133] • Etching time: 24 h

[0134] • Agitator speed: 400 rpm

[0135] (3) Cleaning after etching

[0136] The above slurry was equally divided into two, and inserted into two 50 mL centrifuge tubes. Then, after centrifugation at 3500G for 5 minutes using a centrifuge, the supernatant was discarded. Thereafter, (i) 35 mL of pure water was added to the remaining precipitate in each centrifuge tube, (ii) stirring was performed by hand, (iii) centrifugation was performed at 3500G for 5 minutes, (iv) the supernatant was removed. This (i) to (iv) process was repeated 10 times. Then finally, centrifugation was performed at 3500G for 5 minutes, to obtain Ti3C2T s - Moisture medium clay.

[0137] (4) Li intercalation

[0138] For the Ti3C2T s - Moisture medium clay, Li intercalation was performed using LiCl as the Li-containing compound under the following Li intercalation conditions, stirring at 20°C or higher and 25°C or lower for 12 hours. The detailed conditions for Li intercalation are described below.

[0139] (Li intercalation conditions)

[0140] • Ti3C2T s - Moisture medium clay (cleaned MXene): solid content 0.75 g

[0141] • LiCl: 0.75 g

[0142] • Intercalation container: 100 mL jar

[0143] • Temperature: 20°C or higher and 25°C or lower (room temperature)

[0144] • Time: 12 h

[0145] • Agitator speed: 800 rpm

[0146] (5) Layer separation and water cleaning

[0147] The slurry obtained by the Li intercalation was put into a 50 mL centrifuge tube, and after centrifugation at 3500 G using a centrifugal separator, the supernatant was discarded. Next, (i) after adding 40 mL of pure water to the remaining precipitate, after stirring in a shaker for 15 minutes, (ii) centrifugation was performed at 3500 G, (iii) the supernatant was recovered as a liquid containing single / multi-layer MXene. The operations of (i) to (iii) were repeated a total of 4 times, and a supernatant containing single / multi-layer MXene was obtained. Further, after centrifugation of the supernatant at 4300 G for 2 hours using a centrifugal separator, the supernatant was discarded, and a MXene clay containing single / multi-layer MXene was obtained as the remaining precipitate.

[0148] 2. Preparation of a slurry of a MXene / polymer composite (Example 1, Comparative Example 2)

[0149] In a 50 mL centrifuge tube, 10.9 g of the MXene clay obtained in the aforementioned 1 and 3.1 g of Lipidure (registered trademark) A were measured, and pure water was added so that the concentration of MXene in the mixture was 1.5 mass%. After that, stirring was performed in a shaker for 15 minutes, and a slurry of a MXene / polymer composite as a liquid composition was obtained.

[0150] 3. Preparation of an electrode (Example 1, Comparative Example 1, Comparative Example 2)

[0151] In Example 1, an arbitrary amount of the slurry of a MXene / polymer composite obtained in the aforementioned 2 was taken in a culture dish, and using this slurry, dip coating was performed on the tip portion of a silver / silver chloride individual electrode (brush electrode) manufactured by Datwyler, Soft Pulse. After that, drying of the formed MXene-containing film was performed using a normal pressure oven. The thickness of the obtained MXene-containing film (MXene / polymer composite film) was about 1 μm.

[0152] As Comparative Example 1, a silver / silver chloride individual electrode (brush electrode) which was not covered with the aforementioned MXene-containing film (MXene / polymer composite film) was prepared. Further, as Comparative Example 2, a base material electrode of a silver / silver chloride electrode portion which was not formed on the tip portion of a silver / silver chloride individual electrode (brush electrode) was prepared, and a MXene-containing film individual electrode in which a MXene-containing film (MXene / polymer composite film) was formed on the surface of the base material electrode was prepared.

[0153] 4. Evaluation of samples (determination of impedance)

[0154] The determination of impedance was performed as follows.

[0155] (a) Natus gel electrodes (product number: 019-415200) were set as a counter electrode and a reference electrode on a WetLab-made biochip (product number: HXBNXTB858510MX). In addition, each electrode of Example 1, Comparative Example 1, and Comparative Example 2 prepared in the foregoing 3 were set as a working electrode.

[0156] (b) Impedance measurement was performed using a Metrohm-made electrochemical measurement device (product number: PGSTAT302N). The detailed measurement conditions are described below.

[0157] (Measurement conditions of impedance)

[0158] • Frequency range: 0.1 to 10 5 Hz

[0159] • Plotting number: 61 points

[0160] • Voltage: 10 mVrms

[0161] The measurement results of the above impedance are shown in Figure 7 . According to Figure 7 , as the electrode of the present embodiment, by providing the MXene-containing film on the surface of the silver / silver chloride electrode portion, the impedance is lower than that of the silver / silver chloride electrode alone (Comparative Example 1) in the region of about 0.3 to about 200 Hz. In addition, the impedance is lower than that of the MXene-containing film alone electrode (Comparative Example 2) in the region of about 0.1 Hz to about 0.3 Hz. Thus, the silver / silver chloride electrode alone (Comparative Example 1) and the MXene-containing film alone electrode (Comparative Example 2) have high impedance in a part of the frequency range, in contrast to which, according to the electrode of the present embodiment, the impedance is equivalent to or lower than that of the silver / silver chloride electrode alone (Comparative Example 1) and the MXene-containing film alone electrode (Comparative Example 2) at any frequency, and low impedance is stably exhibited in a relatively low frequency range. As a reason therefor, it is considered that, by forming the prescribed MXene-containing film together with the silver / silver chloride electrode portion on the surface of the electrode substrate, as described above, the impedance reduction effect based on both the MXene-containing film and the silver / silver chloride electrode portion is exhibited.

[0162] [Examples 2 to 4, Comparative Examples 3 to 6]

[0163] 1. Preparation of particles of two-dimensional material

[0164] Particles of two-dimensional material were prepared in the same manner as in Example 1.

[0165] 2. Preparation of slurry of MXene and silver / silver chloride composite

[0166] The layered treatment product (an aqueous slurry of Mxene) obtained in the aforementioned 1. and a silver / silver chloride paste (Dupont 5880) manufactured by Dupont were taken in a 50 mL centrifuge tube in a prescribed amount, and pure water was added so that the concentration of the Mxene would be 1.5 wt%. After that, a shaker was operated for 15 minutes to obtain a slurry of a composite material of Mxene and silver / silver chloride. Slurries in which the volume ratio of Mxene was 21 vol% (Comparative Example 3), 30 vol% (Example 2), 50 vol% (Example 3), 70 vol% (Example 4), and 79 vol% (Comparative Example 4) (the remaining volume ratio was the volume ratio of silver / silver chloride), respectively, were prepared.

[0167] 3. Production of Electrodes (Examples 2 to 4, Comparative Examples 3 to 6)

[0168] The slurry obtained in the aforementioned 2. was applied to a polyimide film having a thickness of 75 μm using a bar coater with a gap of 250 μm to obtain a molded body. Then, using a normal pressure oven, the aforementioned molded body was dried at 80°C for 2 hours to obtain electrodes in which a silver / silver chloride-Mxene dispersion film was formed, which were Example 2 to 4 and Comparative Examples 3 and 4.

[0169] As Comparative Example 5, a silver / silver chloride-only electrode using silver / silver chloride alone (Dupont 5880 alone) instead of the aforementioned silver / silver chloride-Mxene dispersion film was prepared. In addition, as Comparative Example 6, a Mxene film-only electrode using a Mxene film instead of the aforementioned silver / silver chloride-Mxene dispersion film was prepared.

[0170] 4. Evaluation of Samples (Measurement of Impedance)

[0171] The measurement of impedance was performed as follows.

[0172] (a) A gel electrode (product number: 019-415200) manufactured by Natus was set as a counter electrode and a reference electrode on a biological sheet (product number: HXBNXTB858510MX) manufactured by WetLab. In addition, each of the electrodes of Examples 2 to 4 and Comparative Examples 3 to 6 prepared in the aforementioned 3. was set as a working electrode. A Kapton tape punched out in a diameter of φ 3 mm was attached to prepare a measurement electrode having an opening portion in a diameter of φ 3 mm.

[0173] (b) Impedance measurement was performed using an electrochemical measurement device (product number: PGSTAT302N) manufactured by Metrohm. The detailed measurement conditions are described below. Then, a case in which the impedance at 10 Hz was lower than 1 kOhm was evaluated as O (pass), and a case in which the impedance at 10 Hz was 1 kOhm or more was evaluated as X (fail). As a result, Comparative Examples 3 to 6 were X (fail), and Examples 2 to 4 were O (pass).

[0174] (Measurement conditions of impedance)

[0175] • Frequency range: 0.1 to 10 4 Hz

[0176] • Plotting number: 51 points

[0177] • Voltage: 10 mVrms

[0178] In the measurement results, the results of Comparative Example 3 (silver / silver chloride-MXene dispersion film in which the volume ratio of MXene is 21 vol% (indicated as "MXene-silver / silver chloride dispersion" in the present specification), Example 4 (silver / silver chloride-MXene dispersion film in which the volume ratio of MXene is 50 vol% (indicated as "MXene-silver / silver chloride dispersion" in the present specification), Comparative Example 5 (silver / silver chloride alone electrode), and Comparative Example 6 (MXene film alone electrode) are shown in Figure 8 Figure 8 Figure 8 According to Figure 8 , in the case where a film in which silver / silver chloride and MXene are dispersed is formed like the electrode of the present embodiment, a decrease in impedance is also seen. In particular, in Examples 3 to 5 in which the volume ratio of MXene is preferably in the range of 25 to 75 vol%, a sufficient decrease in impedance is seen. As a reason therefor, it is considered that the low conductivity of MXene is improved by silver contained in silver / silver chloride as described above.

[0179] Industrial applicability

[0180] The electrode of the present disclosure can be used for any appropriate use, and for example, can be preferably used as a living body signal sensing electrode.

[0181] <1>

[0182] An electrode having: a substrate, a silver / silver chloride electrode portion, and a film containing particles of a two-dimensional material, the particles of the two-dimensional material containing one or more layers,

[0183] The aforementioned one or more layers contain: a layer main body represented by the following formula, and a modification or a terminal T present at the surface of the layer main body,

[0184] M m X n

[0185] (In the formula, M is at least one metal of Groups 3, 4, 5, 6, and 7 and contains Ti,

[0186] X is a carbon atom, a nitrogen atom, or a combination thereof,

[0187] n is 1 or more and 4 or less, ​​

[0188] m is greater than n and is 5 or less

[0189] (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom).

[0190] <2>

[0191] The electrode according to <1>, wherein the film of the particles containing the two-dimensional material has a thickness of 1 nm or more and 5 μm or less.

[0192] <3>

[0193] The electrode according to <1> or <2>, wherein the silver / silver chloride electrode portion is provided on at least a part of the surface of the substrate, and the film of the particles containing the two-dimensional material is provided on at least a part of the surface of the silver / silver chloride electrode portion exposed to the outside environment.

[0194] <4>

[0195] The electrode according to any one of <1> to <3>, wherein the substrate has a tip portion and a longitudinal direction, the silver / silver chloride electrode portion is provided on the surface of the substrate including the tip portion, and the film of the particles containing the two-dimensional material is provided on the entire surface of the silver / silver chloride electrode portion exposed to the outside environment.

[0196] <5>

[0197] The electrode according to any one of <1> to <4>, which is a brush-shaped electrode having a support body and a plurality of styluses for contacting with a measurement target,

[0198] At least one of the plurality of styluses has a substrate, a silver / silver chloride electrode portion, and a film of particles containing a two-dimensional material, the particles containing the two-dimensional material include one or more layers, and on a portion including a tip of the stylus, the silver / silver chloride electrode portion is provided on at least a part of the surface of the substrate, and the film of the particles containing the two-dimensional material is provided on at least a part of the surface of the silver / silver chloride electrode portion exposed to the outside environment.

[0199] <6>

[0200] The electrode according to any one of <1> to <5>, wherein the film of the particles containing the two-dimensional material contains a polymer.

[0201] <7>

[0202] The electrode according to <6>, wherein the polymer is a water-soluble polymer.

[0203] <8>

[0204] The electrode according to <7>, wherein the aforementioned water-soluble polymer is one or more selected from the group consisting of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS), Lipidure (registered trademark) A, Lipidure (registered trademark) PMB, polyurethane, polyacrylic acid, sodium polyacrylate, and cation-modified PVA.

[0205] <9>

[0206] The electrode according to any one of <1>, <2>, and <6> to <8>, wherein the aforementioned film containing the particles of two-dimensional material also further contains silver / silver chloride, and is also a silver / silver chloride electrode portion.

[0207] <10>

[0208] The electrode according to <9>, wherein the volume ratio of the particles of two-dimensional material in the aforementioned film containing the particles of two-dimensional material is 25 vol% or more and 75 vol% or less.

[0209] <11>

[0210] The electrode according to any one of <1> to <10>, which is a biological signal sensing electrode.

[0211] This application is accompanied by a priority claim based on Japanese Patent Application No. 2023-101021 and a priority claim based on Japanese Patent Application No. 2023-208787. Japanese Patent Application No. 2023-101021 and Japanese Patent Application No. 2023-208787 are hereby incorporated by reference into the present specification.

[0212] Explanation of Reference Signs

[0213] 1a, 1b Layer main body (M m X n Layer)

[0214] 3a, 5a, 3b, 5b Modified or terminal T

[0215] 7a, 7b MXene layer

[0216] 10a, 10b MXene particle (particle of two-dimensional material)

[0217] 20a, 20b, 20c, 30, 40 Electrode

[0218] 21, 41 Electrode base material

[0219] 23 Silver / silver chloride electrode portion

[0220] 25 MXene-containing film

[0221] 27 tip region of stylus

[0222] 31 support body

[0223] 33 stylus

[0224] 43 silver / silver chloride-MXene dispersion film

Claims

1. An electrode, comprising: a substrate, a silver / silver chloride electrode portion, and a film containing particles of a two-dimensional material, the particles of the two-dimensional material comprising one or more layers, the one or more layers comprising: a layer main body represented by the following formula, and a modification or a terminal T present on a surface of the layer main body, M m X n in the formula, M is at least one metal of Groups 3, 4, 5, 6, and 7, and includes Ti, X is a carbon atom, a nitrogen atom, or a combination thereof, n is 1 or more and 4 or less, m is greater than n and 5 or less, T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom.

2. The electrode of claim 1, wherein, The film containing the particles of the two-dimensional material has a thickness of 1 nm or more and 5 μm or less.

3. The electrode according to claim 1 or 2, wherein, The silver / silver chloride electrode portion is disposed on at least a portion of a surface of the substrate, and the film containing the particles of the two-dimensional material is disposed on at least a portion of a surface of the silver / silver chloride electrode portion exposed to an external environment.

4. The electrode according to any one of claims 1 to 3, wherein The substrate has a leading end portion and a longitudinal direction, the silver / silver chloride electrode portion is disposed on a surface of the substrate including the leading end portion, and the film containing the particles of the two-dimensional material is disposed on an entire surface of the silver / silver chloride electrode portion exposed to an external environment.

5. The electrode according to any one of claims 1 to 4, which is a brush-shaped electrode having a support body, and a plurality of styluses for contacting a measurement target, at least one of the plurality of styluses has: a substrate, a silver / silver chloride electrode portion, and a film containing particles of a two-dimensional material, the particles of the two-dimensional material comprising one or more layers, and at a portion including a leading end of the stylus, the silver / silver chloride electrode portion is disposed on at least a portion of a surface of the substrate, and the film containing the particles of the two-dimensional material is disposed on at least a portion of a surface of the silver / silver chloride electrode portion exposed to an external environment.

6. The electrode according to any one of claims 1 to 5, wherein The film containing the particles of the two-dimensional material contains a polymer.

7. The electrode of claim 6, wherein, The polymer is a water-soluble polymer.

8. The electrode of claim 7, wherein, The water-soluble polymer is one or more selected from the group consisting of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS), Lipidure (registered trademark) A, Lipidure (registered trademark) PMB, polyurethane, polyacrylic acid, sodium polyacrylate, and cation-modified PVA.

9. The electrode according to any one of claims 1, 2, and 6-8, wherein, The film containing the particles of the two-dimensional material further contains silver / silver chloride, which is also the silver / silver chloride electrode portion.

10. The electrode of claim 9, wherein, The volume ratio of the particles of the two-dimensional material in the film containing the particles of the two-dimensional material is 25 vol% or more and 75 vol% or less.

11. The electrode according to any one of claims 1 to 10, which is a biological signal sensing electrode.

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