Two-dimensional particles, conductive films, and methods for manufacturing the same

Abstract

The present disclosure aims to provide two-dimensional particles capable of realizing a conductive film with good conductivity stability. 【Solution means】The two-dimensional particles of the present disclosure include one or more layers and a hydrocarbon compound, where the layer has the following formula: M m X n (where M is at least one metal of Groups 3, 4, 5, 6, 7; 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) and includes a layer body represented by the formula and a modification or termination T (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an iodine atom, an oxygen atom, a chlorine atom, a phosphorus atom, and a hydrogen atom) present on the surface of the layer body, and the hydrocarbon compound is present on the layer.

Description

Technical Field

[0001] The present disclosure relates to two-dimensional particles, a conductive film, and a method for manufacturing the same.

Background Art

[0002] In recent years, MXene has attracted attention as a novel conductive material. MXene is a kind of so-called two-dimensional material and is a layered material having one or more layers as described later. Generally, MXene has a form of particles of such a layered material (which may include powders, flakes, nanosheets, etc.).

[0003] Patent Document 1 describes that MXene represented by Ti3C2(OH)2 can be obtained by immersing a Ti2AlC-TiC mixture in an HF solution.

[0004] Non-Patent Document 1 shows that the interlayer delamination of multilayer MXene was performed by shaking using TMAOH (tetramethylammonium hydroxide), and that the interlayer delamination of multilayer MXene was performed by further performing ultrasonic treatment using DMSO (dimethyl sulfoxide).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Documents

[0006]

Non-Patent Document 1

Summary of the Invention

[0007] Although MXene described in Patent Document 1 and Non-Patent Document 1 exhibits conductivity, the stability of its conductivity was not sufficiently satisfactory.

[0008] This disclosure aims to provide two-dimensional particles capable of realizing a conductive film with good conductivity stability, and preferably two-dimensional particles capable of realizing a conductive film with good conductivity stability even in high-temperature environments. This disclosure also aims to provide a conductive film containing such two-dimensional particles and a method for manufacturing such two-dimensional particles. [Means for solving the problem]

[0009] The two-dimensional particles of this disclosure comprise one or more layers and a hydrocarbon compound. The above layer is represented by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The above-mentioned hydrocarbon compound is present on the above layer.

[0010] The method for manufacturing two-dimensional particles described herein is: The method includes heating precursor particles in the presence of an organic compound under conditions of an absolute pressure of less than 1,013 hPa and above the boiling point of the organic compound to obtain two-dimensional particles. The above precursor particles are It contains one terra layer, The aforementioned layer is given by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an iodine atom, an oxygen atom, a chlorine atom, a phosphorus atom, and a hydrogen atom), The melting point of the aforementioned organic compound is 20°C or lower. [Effects of the Invention]

[0011] This disclosure provides two-dimensional particles capable of realizing a film with suppressed conductivity degradation, and preferably, two-dimensional particles capable of realizing a conductive film with suppressed conductivity degradation even in high-temperature environments. This disclosure may also provide a conductive film containing such two-dimensional particles and a method for manufacturing such two-dimensional particles. [Brief explanation of the drawing]

[0012] [Figure 1] A schematic cross-sectional view showing MXene particles of a layered material in one embodiment of the present disclosure, where (a) shows single-layer MXene particles and (b) shows multilayer (exemplary, two-layer) MXene particles. [Figure 2] This is a schematic cross-sectional view showing a film in one embodiment of the present disclosure.

[0013] (First embodiment: 2-dimensional particle) The following describes a two-dimensional particle in one embodiment of the present disclosure.

[0014] The two-dimensional particles of this disclosure comprise one or more layers and a hydrocarbon compound. The above layer is represented by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an iodine atom, an oxygen atom, a chlorine atom, a phosphorus atom, and a hydrogen atom), The hydrocarbon compound is present on the layer.

[0015] According to this disclosure, it is possible to provide two-dimensional particles that can realize a film with suppressed conductivity degradation, and preferably, two-dimensional particles that can realize a conductive film with suppressed conductivity degradation even in high-temperature environments. This disclosure should not be interpreted as being limited to any particular theory, but the reason why the above effect is achieved by the two-dimensional particles of this disclosure is thought to be as follows.

[0016] In other words, although this disclosure should not be interpreted as being limited to any particular theory, one of the causes of a decrease in the conductivity of MXene is the oxidation of MXene. In the two-dimensional particles of this disclosure, since hydrocarbon compounds are present on the MXene layer, it is thought that oxidation of the MXene layer is suppressed even in high-temperature environments. As a result, it is possible to realize a film in which the decrease in conductivity is suppressed, and in particular, it is thought that a conductive film in which the decrease in conductivity is suppressed even in high-temperature environments can be realized.

[0017] In this disclosure, the phrase "a hydrocarbon compound is present on a layer" includes both cases where the hydrocarbon compound is physically or chemically bonded to the layer and cases where the hydrocarbon compound is not bonded to the layer, and may include both cases where the hydrocarbon compound is in contact with the layer and cases where the hydrocarbon compound is not in contact with the layer.

[0018] In the present disclosure, when referring to an element as an "atom", the oxidation number of the element is not limited to 0 and can be any number within the range of oxidation numbers that the element can take.

[0019] In the present disclosure, "hydrocarbon compound" means a compound composed of carbon atoms and hydrogen atoms. The hydrocarbon compound may include aromatic hydrocarbon compounds, saturated or unsaturated aliphatic hydrocarbon compounds, and saturated or unsaturated alicyclic hydrocarbon compounds.

[0020] In the present disclosure, "aromatic hydrocarbon compound" means a hydrocarbon compound containing an aromatic hydrocarbon group. Also, in the present disclosure, "alicyclic hydrocarbon compound" means a hydrocarbon compound containing an alicyclic hydrocarbon group.

[0021] In the present disclosure, the above layer may be referred to as a MXene layer, and the above two-dimensional particles may be referred to as MXene two-dimensional particles or MXene particles.

[0022] The above M m X n In the layer body represented by, each X may have a crystal lattice located within the octahedral array of M.

[0023] Also, the above modification or termination T may be present on the surface of the layer body represented by the above M m X n and may be present, for example, on at least one of the two surfaces of the layer body facing each other. The above modification or termination T preferably contains one or more selected from hydroxyl group, fluorine atom, chlorine atom, iodine atom, SO4 2- and PO4 3- and may more preferably contain one or more selected from chlorine atom, iodine atom, SO4 2- and PO4 3- and may contain one or more selected from them.

[0024] In the present disclosure, the above two-dimensional particles can be understood as a layered material or a layered compound, "M m X n T sIt can also be expressed as , where s is any number, and traditionally, x or z have sometimes been used instead of s. Typically, n can be 1, 2, 3, or 4, but is not limited to these.

[0025] In the above formula for MXene, M is preferably at least one selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and Mn, and more preferably at least one selected from the group consisting of Ti, V, Cr, and Mo.

[0026] MXene is expressed in the above formula: M m X n However, the following expressions are known: Sc2C, Ti2C, Ti2N, Zr2C, Zr2N, Hf2C, Hf2N, V2C, V2N, Nb2C, Ta2C, Cr2C, Cr2N, Mo2C, Mo 1.3 C, Cr 1.3 C, (Ti,V)2C, (Ti,Nb)2C, W2C, W 1.3 C, Mo2N, Nb 1.3 C, Mo 1.3 Y 0.6 C (In the above formula, "1.3" and "0.6" mean approximately 1.3 (=4 / 3) and approximately 0.6 (=2 / 3), respectively.) Ti3C2, Ti3N2, Ti3(CN), Zr3C2, (Ti,V)3C2, (Ti2Nb)C2, (Ti2Ta)C2, (Ti2Mn)C2, Hf3C2, (Hf2V)C2, (Hf2Mn)C2, (V2Ti)C2, (Cr2Ti)C2, (Cr2V)C 2, (Cr2Nb)C2, (Cr2Ta)C2, (Mo2Sc)C2, (Mo2Ti)C2, (Mo2Zr)C2, (Mo2Hf)C2, (Mo2V)C2, (Mo2Nb)C2, (Mo2Ta)C2, (W2Ti)C2, (W2Zr)C2, (W2Hf)C2, Ti4N3, V4C3, Nb4C3, Ta4C3, (Ti,Nb)4C3, (Nb,Zr)4C3, (Ti2Nb2)C3, (Ti2Ta2)C3, (V2Ti2)C3, (V2Nb2)C3, (V2Ta2)C3, (Nb2Ta2)C3, (Cr2Ti2)C3, (Cr2V 2)C3, (Cr2Nb2)C3, (Cr2Ta2)C3, (Mo2Ti2)C3, (Mo2Zr2)C3, (Mo2Hf2)C3, (Mo2V2)C3, (Mo2Nb2)C3, (Mo2Ta2)C3, (W2Ti2)C3, (W2Zr2)C3, (W2Hf2)C3, (Mo 2.7 V 1.3 )C3 (In the above formula, "2.7" and "1.3" mean approximately 2.7 (=8 / 3) and approximately 1.3 (=4 / 3), respectively.)

[0027] Typical examples include M m X n However, Ti2C, Ti3C2, Ti3(CN), (Cr2Ti)C2, (Mo2Ti)C2, (Mo2Ti2)C3, and (Mo 2.7 V 1.3 ) Represented by at least one selected from the group consisting of C3.

[0028] Typically, in the above formula, M can be titanium or vanadium, and X can be a carbon atom or a nitrogen atom. For example, the MAX phase is Ti3AlC2, the main layer is Ti3C2, and MXene is Ti3C2T s It is possible (in other words, M is Ti, X is C, n is 2, and m is 3). In particular, M m X n This could be Ti3C2.

[0029] In this disclosure, MXene may contain a relatively small amount of A atoms derived from the precursor MAX phase, for example, 10% by mass or less relative to 100% by mass of the total amount of A atoms contained in the precursor MAX phase. The residual amount of A atoms may preferably be 0% by mass or more and 8% by mass or less, more preferably 0% by mass or more and 6% by mass or less, relative to 100% by mass of the total amount of A atoms contained in the precursor MAX phase. However, even if the residual amount of A atoms exceeds 10% by mass, it may not be a problem depending on the application and usage conditions of the two-dimensional particles.

[0030] The above two-dimensional particle is an aggregate containing one layer of MXene particles (hereinafter simply referred to as "MXene particles") 10a (single-layer MXene particles), schematically illustrated in Figure 1(a). More specifically, the MXene particle 10a is M m X n The layer body (M) represented by m X n The MXene layer 7a has a layer 1a and modifications or terminations T3a, 5a present on the surface of the layer body 1a (more specifically, at least one of the two surfaces facing each other in each layer). Therefore, the MXene layer 7a is "M m X n T s It can also be expressed as , where s is any number. Note that hydrocarbon compounds are not shown in Figure 1(a).

[0031] The above two-dimensional particles may include one or more layers. As an example of MXene particles with multiple layers (multilayer MXene particles), two layers of MXene particles 10b are shown schematically in Figure 1(b), but the example is not limited to these. In Figure 1(b), 1b, 3b, 5b, and 7b are the same as 1a, 3a, 5a, and 7a in Figure 1(a) described above. Two adjacent MXene layers of multilayer MXene particles (e.g., 7a and 7b) do not necessarily have to be completely separated, but may be partially in contact. The above MXene particle 10a is a single layer in which the multilayer MXene particles 10b are individually separated, and there may be remaining unseparated multilayer MXene particles 10b, resulting in a mixture of single-layer MXene particles 10a and multilayer MXene particles 10b. Note that hydrocarbon compounds are not shown in Figure 1(b).

[0032] Although not limited to this embodiment, the thickness of each layer contained in the MXene particles (corresponding to the MXene layers 7a and 7b described above) is, for example, 0.8 nm to 5 nm, and more particularly 0.8 nm to 3 nm (this may vary mainly depending on the number of M atomic layers contained in each layer). For each stack of the multilayer MXene particles that may be contained, the interlayer distance (or void dimension, shown as Δd in Figure 1(b)) may be, for example, 0.8 nm to 10 nm, more particularly 0.8 nm to 5 nm, and more specifically 0.8 nm to 1.5 nm. The total number of layers may be 2 or more and 20,000 or less.

[0033] In one embodiment, the two-dimensional particles in this embodiment preferably include two-dimensional particles with a small number of layers, obtained by delamination, which may be included as described above. "Small number of layers" means, for example, that the number of stacked MXene layers is 6 or less. Furthermore, the thickness in the stacking direction of the multilayer MXene particles with a small number of layers is preferably 15 nm or less, and more preferably 10 nm or less. Hereinafter, these "multilayer MXene particles with a small number of layers" may be referred to as "low-layer MXene particles." Also, single-layer MXene particles and low-layer MXene particles may be collectively referred to as "single-layer / low-layer MXene particles." By including single-layer / low-layer MXene particles, the conductivity of the resulting film can be increased.

[0034] The two-dimensional particles in this embodiment preferably include single-layer MXene particles and thin-layer MXene particles, i.e., single-layer and thin-layer MXene particles. In the two-dimensional particles of this embodiment, the proportion of single-layer and thin-layer MXene particles with a thickness of 15 nm or less is preferably 90% by volume or more, and more preferably 95% by volume or more.

[0035] In one embodiment, the ratio of (average value of the major axis of the two-dimensional surface of the two-dimensional particle) / (average value of the thickness of the two-dimensional particle) is, for example, 1.2 or more, preferably 1.5 or more, and more preferably 2 or more. The average value of the major axis of the two-dimensional surface of the two-dimensional particle and the average value of the thickness of the two-dimensional particle can be determined by the method described later.

[0036] (Average value of the major axis of the two-dimensional plane of a two-dimensional particle) In this embodiment, the average value of the major axis of the two-dimensional surface of the two-dimensional particles is, for example, 1 μm or more and 20 μm or less. Hereinafter, the average value of the major axis of the two-dimensional surface may be referred to as the "average flake size".

[0037] The larger the average flake size, the higher the conductivity of the film. In this embodiment, the two-dimensional particles have a large average flake size of 1.0 μm or more, so a film formed using these two-dimensional particles, for example, a film obtained by stacking these two-dimensional particles, can achieve a conductivity of 2000 S / cm or more. The average value of the major axis of the two-dimensional surface is preferably 1.5 μm or more, more preferably 2.5 μm or more. When MXene is delaminated by ultrasonic treatment, most of the MXene is reduced in diameter to about several hundred nm by ultrasonic treatment, so a film formed from single-layer MXene delaminated by ultrasonic treatment is considered to have low conductivity.

[0038] The average value of the major axis of the two-dimensional surface is, from the viewpoint of dispersibility in the dispersion medium, for example, 20 μm or less, preferably 15 μm or less, and more preferably 10 μm or less.

[0039] The major axis of the two-dimensional plane mentioned above refers to the major axis when each MXene particle is approximated as an ellipse in the electron microscope image, and the average value of the major axis of the two-dimensional plane refers to the average of the number of major axes for 80 or more particles. Scanning electron microscopes (SEM) and transmission electron microscopes (TEM) can be used as electron microscopes.

[0040] The average length of the two-dimensional particles in this embodiment may be measured by dissolving the film containing the two-dimensional particles in a solvent and dispersing the two-dimensional particles in the solvent. Alternatively, it may be measured from an SEM image of the film.

[0041] (Average thickness of 2D particles) The average thickness of the two-dimensional particles in this embodiment is preferably between 1 nm and 15 nm. The above thickness is preferably 10 nm or less, more preferably 7 nm or less, and even more preferably 5 nm or less. On the other hand, considering the thickness of the single-layer MXene particles, the lower limit of the two-dimensional particle thickness can be 1 nm.

[0042] The average thickness of the above two-dimensional particles is determined as a number-average dimension (e.g., a number-average of at least 40 particles) based on atomic force microscope (AFM) or transmission electron microscope (TEM) images.

[0043] The above two-dimensional particles contain hydrocarbon compounds. Since the hydrocarbon compounds are greater than the interatomic distances of each atom within the layer body, they are considered to be present on the layer. As described above, in this disclosure, when we say that "hydrocarbon compounds are present on the layer," it includes both cases in which the hydrocarbon compounds are physically or chemically bonded to the layer and cases in which the hydrocarbon compounds are not bonded to the layer, and cases in which the hydrocarbon compounds are in contact with the layer and cases in which the hydrocarbon compounds are not in contact with the layer. It is believed that the inclusion of hydrocarbon compounds in this manner can suppress oxidation of the layer, which can contribute to suppressing a decrease in conductivity, and further to suppressing a decrease in conductivity under high-temperature conditions.

[0044] The hydrocarbon compounds described above are typically compounds consisting of carbon atoms and hydrogen atoms, and may include aromatic hydrocarbon compounds, saturated or unsaturated aliphatic hydrocarbon compounds, and saturated or unsaturated alicyclic hydrocarbon compounds. Preferably, the hydrocarbon compounds include one or more selected from aromatic hydrocarbon compounds and saturated or unsaturated aliphatic hydrocarbon compounds, and more preferably, one or more selected from saturated or unsaturated aliphatic hydrocarbon compounds.

[0045] The above aromatic hydrocarbon compound may preferably be an aromatic hydrocarbon compound having 6 to 20 carbon atoms, more preferably an aromatic hydrocarbon compound having 6 to 10 carbon atoms, specifically including toluene and xylene.

[0046] The above saturated aliphatic hydrocarbon compound may preferably be a saturated aliphatic hydrocarbon compound having 1 to 20 carbon atoms, more preferably a saturated aliphatic hydrocarbon compound having 4 to 10 carbon atoms, and specifically include butane, isobutane, 2-methylbutane, 2-methylpentane, 2,4-dimethylpentane, 2-methylheptane, and octane.

[0047] The above unsaturated aliphatic hydrocarbon compounds are preferably unsaturated aliphatic hydrocarbon compounds having 2 to 20 carbon atoms, and more preferably unsaturated aliphatic hydrocarbon compounds having 3 to 10 carbon atoms. Specifically, examples include propene, isobutene, pentene, 2-methylbutene, 2-methylpentene, 2-methylhexene, and octene.

[0048] The saturated or unsaturated alicyclic hydrocarbon compounds mentioned above are preferably saturated or unsaturated alicyclic hydrocarbon compounds having 3 to 20 carbon atoms, and more preferably saturated or unsaturated alicyclic hydrocarbon compounds having 6 to 10 carbon atoms. Specifically, examples include cyclohexane, methylcyclohexane, cyclohexene, and methylcyclohexene.

[0049] The types of hydrocarbon compounds contained in the above two-dimensional particles can be identified by gas chromatography-mass spectrometry (GC-MS). Gas chromatography analysis can typically be performed using a gas chromatography-mass spectrometry (GC-MS) instrument equipped with a bilorizer.

[0050] The carbon content derived from the above hydrocarbon compound is preferably 0.5% by mass or more, more preferably 0.5% by mass or more and 5% by mass or less, and even more preferably 0.7% by mass or more and 3% by mass or less, based on 100% by mass of the total amount of two-dimensional particles. Having the carbon content derived from the above hydrocarbon compound within this range makes it easier to improve the stability of conductivity while maintaining conductivity.

[0051] The carbon atom content derived from the above hydrocarbon compounds can be measured by carbon-sulfur analysis (CS analysis). In one embodiment, for example, the above M m X n If the material is Ti3C2, the carbon content derived from the hydrocarbon compound can be calculated by subtracting the amount of carbon atoms calculated assuming that the entire layer of the two-dimensional particles (the layer body and modifications or terminal T) is represented by Ti3C2O2 from the total amount of carbon atoms measured by carbon-sulfur analysis (CS analysis).

[0052] In the above two-dimensional particle, the interlayer distance may preferably be 0.8 nm or more and 1.1 nm or less. This interlayer distance can be determined by X-ray diffraction measurement (XRD) d 002 It can be measured as follows.

[0053] (Second embodiment: Method for producing two-dimensional particles) The following describes in detail a method for producing two-dimensional particles in one embodiment of the present disclosure, but the present disclosure is not limited to such embodiment.

[0054] The two-dimensional particles of this embodiment are The method includes heating precursor particles in the presence of an organic compound under conditions of an absolute pressure of less than 1,013 hPa and above the boiling point of the organic compound to obtain two-dimensional particles. The above precursor particles are It contains one terra layer, The aforementioned layer is given by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an iodine atom, an oxygen atom, a chlorine atom, a phosphorus atom, and a hydrogen atom), The melting point of the aforementioned organic compound is 20°C or lower.

[0055] The method for manufacturing two-dimensional particles according to this disclosure can provide two-dimensional particles that enable the realization of conductive films with good conductivity stability. Although this disclosure should not be interpreted as being limited to any particular theory, the reason why the manufacturing method according to this disclosure achieves the above effect is thought to be as follows.

[0056] In other words, in the method for producing two-dimensional particles of this disclosure, precursor particles are heated at a temperature above the boiling point of a liquid organic compound under reduced pressure in the presence of the organic compound. It is believed that heating under these conditions generates hydrocarbon compounds on the layers contained in the precursor particles, and that the hydrocarbon compounds suppress the oxidation of the layers, thereby improving the stability of the conductivity. The reason for the generation of hydrocarbon compounds is not clear, but it is thought that the MXene layers are in close proximity to each other, and modifications or terminal T are present on the surface of the layers, and that the space between the MXene layers is in a highly active state. It is thought that the presence of an organic compound in this state promotes the generation of hydrocarbon compounds.

[0057] The above organic compound has a melting point of 20°C or lower at 1 atmosphere (1,013 hPa). Having a melting point of 20°C or lower allows the organic compound to penetrate into the precursor particles, making it easier to obtain two-dimensional particles containing hydrocarbon compounds. The melting point of the organic compound is preferably 10°C or lower, more preferably between -50°C and 5°C, and even more preferably between -20°C and 0°C.

[0058] The boiling point of the above organic compound is, for example, 285°C or lower, preferably 240°C or lower, more preferably 200°C or lower, and for example, 50°C or higher.

[0059] The dielectric constant of the above organic compound is preferably 60 or higher, more preferably 60 to 300, and even more preferably 60 to 250. It is believed that the hydrocarbon compound is more likely to precipitate when the dielectric constant of the organic compound is within this range.

[0060] The above organic compounds are soluble in or miscible with water. The solubility of the above organic compounds in water is 5 g / 100 g H2O or more at 25°C, and more preferably 10 g / 100 g H2O or more. In this specification, solubility when miscible with water is treated as infinite.

[0061] The above organic compound is preferably a highly polar compound. In this specification, a highly polar compound is defined not only as a compound exhibiting clear charge separation, but also as a compound with high hydrophilicity. The polarity of a compound can be evaluated using its solubility parameter as an indicator. The Hildebrand solubility parameter (also called the "SP value") of the above organic compound is 19.0 MPa. 1 / 2 That concludes the explanation. The SP value of the organic compound is preferably less than or equal to the SP value of water, at 47.8 MPa. 1 / 2 The following applies: The SP value is an indicator of a compound's polarity; the larger the SP value, the more polar the compound. Compounds with similar SP values ​​tend to be more compatible with each other.

[0062] The molecular weight of the above organic compound is, for example, 500 or less, preferably 300 or less, more preferably 200 or less, and for example, 30 or more.

[0063] Examples of the above organic compounds include organic compounds having one or more of the following groups: carbonyl group, ester group, amide group, formamide group, carbamoyl group, carbonate group, aldehyde group, ether group, sulfonyl group, sulfinyl group, hydroxyl group, cyano group, and nitro group. Preferably, organic compounds having an amide group are mentioned. Specifically, examples of organic compounds include alcohols such as methanol (MeOH), ethanol (EtOH), and 2-propanol; sulfone compounds such as sulfolane; sulfoxides such as dimethyl sulfoxide (DMSO); carbonic acid such as propylene carbonate (PC); amides such as N-methylformamide (NMF), N,N-dimethylformamide, N-methylpyrrolidone (NMP), and dimethylacetamide (DMAc); ketones such as acetone and methyl ethyl ketone (MEK); and tetrahydrofuran (THF). Preferably, amides are mentioned.

[0064] The pressure during heating described above is less than 1,013 hPa as an absolute pressure, preferably 1,000 hPa or less, more preferably 50 hPa to 1,000 hPa, and even more preferably 100 hPa to 1,000 hPa. It is believed that this pressure range allows the MXene layer to be maintained and facilitates the formation of hydrocarbon compounds.

[0065] The heating temperature is above the boiling point of the organic compound, preferably 200°C or higher, more preferably 200°C to 400°C, and even more preferably 200°C to 350°C. It is believed that this temperature range allows the layered structure of MXene to be maintained and facilitates the formation of hydrocarbon compounds.

[0066] The heating time is preferably 1 hour to 30 hours, and more preferably 5 hours to 20 hours.

[0067] Pre-drying may be performed before the above heating. Such pre-drying can be carried out under normal pressure at a temperature of 80°C or lower. The pressure during pre-drying may be preferably 900 hPa to 1,200 hPa as absolute pressure, and more preferably 950 hPa to 1,160 hPa as absolute pressure. The temperature during pre-drying may be 10°C or lower, preferably 10°C to 80°C, more preferably 20°C to 70°C, and even more preferably 30°C to 70°C. The pre-drying time is, for example, 30 minutes to 10 hours, preferably 1 hour to 5 hours.

[0068] The amount of the above organic compound may be preferably 5 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 99 parts by mass or less, per 1 part by mass of precursor particles, but is not limited thereto.

[0069] The above precursor particles are typically, (a) Prepare a predetermined precursor, (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Clean the etched material to obtain an etched and cleaned material. (d) Mixing the etching and cleaning treatment product with an intercalator to obtain an intercalation treatment product, and (e) The product may be produced by a manufacturing method which includes stirring the intercalation product to obtain a delamination product containing precursor particles, but is not limited to this embodiment.

[0070] The method for coexisting the above-mentioned precursor particles and organic compounds is not particularly limited. For example, the following methods (d1), (f), (g): (d1) Use an organic compound as an intercalator. (f) Mixing delamination treatment with an organic compound, (g) drying the delamination treatment and then mixing it with an organic compound; this may be carried out by one or more operations selected from these, but is not limited to these.

[0071] The following details each step.

[0072] ·Process (a) First, a predetermined precursor is prepared. In this embodiment, the predetermined precursor that can be used is the MAX phase, which is a precursor of MXene. The following formula: M m AX n (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal containing at least Ti, X is a carbon atom, a nitrogen atom, or a combination thereof. A is at least one element from groups 12, 13, 14, 15, or 16. n is between 1 and 4, m is greater than n and less than or equal to 5. It is represented as follows.

[0073] The above M, X, n, and m are as described above.

[0074] A is at least one element from groups 12, 13, 14, 15, or 16, usually a group A element, typically from groups IIIA and IVA, and more specifically, may include at least one selected from the group consisting of Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, S, and Cd, preferably Al.

[0075] The MAX phase is M m X n It has a crystal structure in which a layer composed of A atoms is located between two layers represented by M. m X n The two layers represented by can have a crystal lattice in which each X is located within an octahedral array of M. In the MAX phase, typically when m=n+1, one layer of X atoms is placed between each of the n+1 layers of M atoms (these together are called "M").m X n It has, but is not limited to, a repeating unit in which a layer of A atoms ("A atomic layer") is placed as the layer following the n+1th M atom layer (also called a "layer").

[0076] The MAX phase described above can be manufactured by known methods. For example, TiC powder, Ti powder, and Al powder can be mixed in a ball mill, and the resulting mixed powder can be calcined in an Ar atmosphere to obtain a calcined body (block-shaped MAX phase). The calcined body can then be crushed with an end mill to obtain powdered MAX phase for the next process.

[0077] ·Process (b) In step (b), the above precursor M is removed using an etching solution. m AX n An etching process is performed to remove at least some of the A atoms from the precursor. m X n A processed material is obtained in which the layer represented by remains intact, while at least a portion of the layer composed of A atoms is removed.

[0078] The etching solution described above may contain acids such as HF, HCl, HBr, HI, sulfuric acid, phosphoric acid, and nitric acid, and typically an etching solution containing F atoms can be used. Examples of such etching solutions include a mixture of LiF and hydrochloric acid; a mixture of hydrofluoric acid and hydrochloric acid; and a mixture containing hydrofluoric acid. These mixtures may further contain phosphoric acid or the like. The etching solution described above is typically an aqueous solution.

[0079] Conventional conditions can be used for the etching operation using the above-mentioned etching solution and other related conditions.

[0080] ·Process (c) In step (c), the etched material obtained by the etching process is washed to obtain an etched-cleaned material. Washing thoroughly removes the acid and other substances used in the etching process.

[0081] Cleaning can be carried out using a cleaning solution, typically by mixing the etched material with the cleaning solution. Such a cleaning solution typically contains water, and pure water is preferred. Alternatively, it may also contain a small amount of hydrochloric acid or the like. The amount of cleaning solution mixed with the etched material and the method of mixing are not particularly limited. For example, such mixing methods include allowing the etched material and cleaning solution to coexist and performing stirring, centrifugation, etc. Stirring methods include using a handshake, automatic shaker, shear mixer, pot mill, etc. The degree of stirring, such as stirring speed and stirring time, should be adjusted according to the amount and concentration of the etched material to be treated. One or more cleanings with the above cleaning solution are sufficient, and it is preferable to perform multiple cleanings. For example, the washing with the washing solution described above may be carried out by sequentially performing steps (i) adding the washing solution (to the treated material or the remaining precipitate obtained in (iii) below) and stirring, step (ii) centrifuging the stirred material, and step (iii) discarding the supernatant after centrifugation. Steps (i) to (iii) may be repeated two or more times, for example, up to 15 times.

[0082] ·Process (d) In step (d), an intercalation process is performed using an intercalator to obtain an intercalated product.

[0083] Examples of the above-mentioned intercalators include metal compounds containing metal cations, the above-mentioned organic compounds, and organic salts.

[0084] The above-mentioned metal cation may be the same as the metal cation contained in the above-mentioned two-dimensional particle.

[0085] Examples of the above-mentioned metal compounds include ionic compounds in which the above-mentioned metal cation and anion are bonded. For example, examples of the above-mentioned metal cation include iodide, phosphate, sulfate, sulfide salt, nitrate, acetate, and carboxylate salts. As the above-mentioned metal cation, alkali metal ions and alkaline earth metal cations are preferred, and lithium ions are more preferred. As the metal compound, metal compounds containing alkali metal ions and alkaline earth metal ions are preferred, metal compounds containing lithium ions are more preferred, ionic compounds of lithium ions are even more preferred, and one or more of lithium ion iodide, phosphate, and sulfide salts are particularly preferred. If lithium ions are used as the metal ions, it is thought that monolayer formation is easier because the water hydrated with the lithium ions has the most negative dielectric constant.

[0086] When a metal compound containing a metal cation is used as an intercalator, the metal cation can be intercalated into the etched and cleaned material. This allows the metal cation to intercalate into two adjacent M m X n An intercalated product is obtained, with layers intercalated between them.

[0087] The above organic compound is synonymous with the organic compound that is present when heating the precursor particles.

[0088] When an organic compound is used as an intercalator, the organic compound is intercalated into the etched and cleaned material. As a result, the organic compound intercalates into two adjacent M m X n An intercalated product is obtained, with layers intercalated between them.

[0089] Examples of the above organic salts include organic salts containing an organic cation and anion. Examples of the above organic cation include ammonium cation, and examples of the above anion include hydroxide ions and chloride ions. Examples of the above organic salts include ammonium salts. Specific examples of the above organic salts include tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), and tetrabutylammonium chloride.

[0090] When an organic salt is used as an intercalator, the organic cations constituting the organic salt can be intercalated into the etched and cleaned material. As a result, the organic cations can intercalate into two adjacent M m X n An intercalated product is obtained, with layers intercalated between them.

[0091] Such intercalation processing may be carried out in a dispersed medium. The specific method of intercalation processing is not particularly limited; for example, the etched and cleaned material and the metal compound may be mixed and stirred, or left to stand. For example, stirring at room temperature is one option. Examples of the stirring methods include using a stirring bar such as a stirrer, using a stirring blade, using a mixer, and using a centrifugal apparatus. The stirring time can be set according to the production scale of single-layer and small-layer MXene particles, for example, between 12 and 24 hours.

[0092] Intercalation processing may be carried out in the presence of a dispersion medium. Examples of dispersion media include water; organic media such as N-methylpyrrolidone, N-methylformamide, N,N-dimethylformamide, methanol, ethanol, dimethyl sulfoxide, ethylene glycol, and acetic acid.

[0093] The mixing order of the dispersion medium, the etched and cleaned material, and the metal compound is not particularly limited, but in one embodiment, the metal compound may be mixed after the dispersion medium and the etched and cleaned material have been mixed. Typically, the etching solution after etching may be used as the dispersion medium.

[0094] Intercalation treatment can typically be performed on an etched and cleaned product, but in another embodiment, it may be performed on the precursor simultaneously with the etching treatment. Specifically, such etching and intercalation treatment involves mixing the precursor, an etching solution, and a metal compound containing metal cations to remove at least some A atoms from the precursor, and intercalating the metal cations into the precursor from which the A atoms have been removed, thereby obtaining an intercalated product. As a result, at least some A atoms are removed from the precursor (MAX), and M in the precursor is also removed. m X n The layer remains, and multiple adjacent M m X n An intercalated product is obtained in which metal cations are intercalated between the layers.

[0095] The etching solution and metal compound used in the above etching and intercalation processes can be the same as those used in step (b), respectively.

[0096] ·Process (d1) In step (d) above, by using the organic compound as an intercalator, the resulting precursor particles can be made to coexist with the organic compound. Step (d1) can be carried out in the same manner as step (d) above, except that the organic compound is used as an intercalator.

[0097] ·Process (e) In step (e), the intercalation material is stirred to perform a delamination process, thereby obtaining a delaminated material. This stirring applies shear stress to the intercalation material, causing two adjacent M m X n At least a portion of the layers may be separated, and the MXene particles may be made into single or multiple layers.

[0098] The conditions for the delamination process are not particularly limited and can be carried out by known methods. For example, one method of applying shear stress to the intercalation material is to disperse the intercalation material in a dispersion medium and stir it. Stirring methods include stirring using a mechanical shaker, vortex mixer, homogenizer, ultrasonic treatment, handshake, automatic shaker, etc. The degree of stirring, such as stirring speed and stirring time, should be adjusted according to the amount and concentration of the material to be treated. For example, after the above intercalation slurry is centrifuged and the supernatant is discarded, pure water is added to the remaining precipitate, and layer separation (delamination) is performed by stirring, for example, by handshake or automatic shaker. Removal of undelaminate material is a process of centrifugation, discarding the supernatant, and washing the remaining precipitate with water. For example, (i) pure water is added to the precipitate remaining after discarding the supernatant and stirred, (ii) centrifuged, and (iii) the supernatant is recovered. These operations (i) to (iii) are performed once or more, preferably twice or more. The process can be repeated 10 times or less to obtain a supernatant liquid containing single-layer and thin-layer MXene particles as the delamination product. Alternatively, this supernatant liquid may be centrifuged, the supernatant liquid after centrifugation discarded, and clay containing single-layer and thin-layer MXene particles may be obtained as the delamination product.

[0099] The delamination treatment materials described above may be further washed before being subjected to the next process.

[0100] In one embodiment, the above cleaning may be carried out using a cleaning solution, typically by mixing the delamination product with the cleaning solution. In another embodiment, the above cleaning may be carried out by acid-treating the delamination product and then mixing the acid-treated product with the cleaning solution. The acid used for such acid treatment may be an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, hydroiodic acid, hydrobromic acid, or hydrofluoric acid; or an organic acid such as acetic acid, citric acid, oxalic acid, benzoic acid, or sorbic acid, and the concentration of the acid in the acid solution may be adjusted as appropriate depending on the delamination product. Furthermore, the cleaning with the above cleaning solution may be carried out by sequentially performing steps (i) adding the cleaning solution (to the treated product or the remaining precipitate obtained in (iii) below) and stirring, step (ii) centrifuging the stirred product, and step (iii) discarding the supernatant after centrifugation, and steps (i) to (iii) may be repeated two or more times, for example, up to 15 times. The above stirring can be carried out using a handshake, automatic shaker, shear mixer, pot mill, etc. Acid treatment is performed. It is sufficient to perform this process once or more, and if necessary, the mixing and stirring operation with a fresh acid solution (an acid solution not used in the acid treatment) may be performed two or more times, for example, up to 10 times. The washing solution used above can be the same as the washing solution used in step (c), and specifically, water may be used as the washing solution, and pure water is preferred. The mixing above can be carried out by the same method as the mixing method in step (c), and specifically, stirring, centrifugation, etc. Examples of stirring methods include handshakes, automatic shakers, shear mixers, pot mills, etc.

[0101] ·Process (f) In step (f), the delamination material and the organic compound are mixed. This allows the organic compound to be inserted between the layers. In step (f), the mixing of the delamination material and the organic compound means mixing them from a state in which they are completely separated to a state in which the organic compound can be present in the delamination material.

[0102] The method for mixing the delamination product with the above-mentioned organic compound is not particularly limited and can be carried out by known methods. For example, a method of stirring and dispersing the above-mentioned organic compound and the delamination product can be used. Stirring methods include stirring using a mechanical shaker, vortex mixer, homogenizer, ultrasonic treatment, handshake, automatic shaker, etc. The degree of stirring, such as the stirring speed and stirring time, can be adjusted according to the amount and concentration of the product to be treated. In one embodiment, the content of the delamination product in the mixture containing the delamination product and the above-mentioned organic compound may be, for example, 0.5% by mass or more and 10% by mass or less, and more specifically, 1% by mass or more and 5% by mass or less.

[0103] When mixing the delamination treatment product and the organic compound, other dispersion media may be present. Examples of other dispersion media include water. The organic compound and the other dispersion media may be mixed such that the volume ratio of the organic compound to the other dispersion media (organic compound / other dispersion media) is, for example, 50 / 50 or more, preferably 55 / 45 or more.

[0104] When mixing the delamination treatment material and the organic compound, a resin may be added as needed. This yields a conductive film containing two-dimensional particles and resin.

[0105] ·Process (g) In step (g), the delamination-treated material is dried and then mixed with the organic compound. Drying the delamination-treated material removes the moisture contained in it. Hereinafter, the material obtained by drying the delamination-treated material will also be referred to as the dried material.

[0106] The drying method may be carried out under mild conditions such as natural drying (typically placed in an air atmosphere at room temperature and atmospheric pressure) or air drying (blowing air), or under relatively active conditions such as hot air drying (blowing heated air), heat drying, vacuum drying and / or freeze drying. In step (g), it is preferable to remove as much water as possible contained in the delamination material, and from this viewpoint, drying under active conditions is preferable. Also, in step (g), it is preferable to remove water without heating to a high temperature. For example, the drying temperature in step (g) may be preferably 190°C or lower, more preferably 150°C or lower, even further 140°C or lower, and particularly 120°C or lower. In one embodiment, it may be less than 20°C, and even further 10°C or lower. From this viewpoint, vacuum drying and / or freeze drying are preferred as drying methods, and freeze drying is even more preferred.

[0107] In this drying process, the dispersion medium can be removed from the delamination treatment material, and typically a film-like dried material is obtained.

[0108] The mixing of the dried material and the organic compound can be carried out by any method, for example, by impregnating the dried material with the organic compound, or by immersing the dried material with the organic compound.

[0109] In this embodiment, the amount of the dried product may be, for example, 0.5 parts by mass or more and 1 to 5 parts by mass, per 100 parts by mass of the organic compound.

[0110] (Third embodiment: conductive film)

[0111] A conductive film in one embodiment of the present disclosure will be described in detail below, but the present disclosure is not limited to such embodiment.

[0112] The conductive film of this embodiment contains the above-mentioned two-dimensional particles and has an electrical conductivity of 2,000 S / cm or more.

[0113] This can provide a conductive film with good conductivity stability. Although this disclosure should not be interpreted as being limited to any particular theory, the reason why the conductive film of this disclosure may exhibit such an effect is thought to be as follows: The conductive film of this disclosure contains the above-mentioned two-dimensional particles, and in such two-dimensional particles, a hydrocarbon compound is present on the MXene layer. Therefore, oxidation of the MXene layer can be suppressed even in high-temperature environments, and it is thought that a conductive film with good conductivity stability, especially in high-temperature environments, can be provided.

[0114] The conductivity of the above conductive film is preferably 2,000 S / cm or more, more preferably 5,000 S / cm or more, and even more preferably 7,000 S / cm or more, and is usually 25,000 S / cm or less.

[0115] When the above conductive film is analyzed by X-ray photoelectron spectroscopy (XPS), the ratio of the area of ​​peaks attributed to divalent and trivalent Ti to the total area of ​​peaks attributed to Ti2p (hereinafter also referred to as the "Ti2p area ratio") is preferably 80% to 100%, more preferably 85% to 100%, and even more preferably 90% to 100%. The larger the Ti2p area ratio, the more the oxidation of the MXene layer surface is suppressed, and the better the stability of the conductivity may be. As oxidation progresses, the area of ​​peaks attributed to tetravalent Ti increases, and the Ti2p area ratio decreases.

[0116] When the above conductive film is heat-treated at 300°C for 2 hours under normal pressure, if the Ti2p area ratio before heat treatment is A0 and the Ti2p area ratio after heat treatment is A1, the ratio of A1 to A0, A1 / A0, is preferably 80% to 100%, more preferably 85% to 100%, and even more preferably 90% to 100%. Having the above ratio A1 / A0 within this range suppresses oxidation of the MXene layer surface, resulting in good conductivity stability.

[0117] The content of two-dimensional particles in the conductive film described above is preferably 70% by volume or more and 100% by volume or less, more preferably 90% by volume or more and 100% by volume or less, and even more preferably 95% by volume or more and 100% by volume or less.

[0118] The conductive film described above may further contain a resin in addition to the two-dimensional particles. Such a resin can be one or more selected from thermosetting resins, thermoplastic resins, and conductive polymers.

[0119] Examples of the thermosetting resins mentioned above include epoxy resins, epoxy acrylate resins, phenol novolac type epoxy resins, phenolic resins, urethane resins, silicone resins, polyamide resins, polyimide resins, polyamide-imide resins, and lipids. A single thermosetting resin may be used, or two or more may be used in combination.

[0120] Examples of the thermoplastic resins mentioned above include polyolefin resins (e.g., polyethylene resin, polypropylene resin), polyvinyl chloride, polystyrene resin, polyvinyl acetate, acrylic resin, polyester resin, polylactic acid, polyurethane resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, fluoropolymer resin, liquid crystal polymer, polyacrylic acid, polyether resin, polyphenyl sulfide resin, diallyl phthalate resin, polyvinyl alcohol resin (e.g., cation-modified polyvinyl alcohol), epoxy resin without curing agent, and phenoxy resin without curing agent. The thermoplastic resin may be used alone or in combination of two or more types.

[0121] Examples of the conductive polymers mentioned above include poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS), polyaniline, polypyrrole, and polythiophene. A single conductive polymer may be used, or two or more may be used in combination.

[0122] The resins mentioned above are preferably polyurethane resin, polyacrylic acid, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS).

[0123] Furthermore, the above-mentioned film may further contain other additives.

[0124] The method for manufacturing a conductive film in this embodiment includes forming a conductive film using the above-mentioned two-dimensional particles, and in one embodiment, a precursor film containing precursor particles is heated in the presence of an organic compound under conditions of an absolute pressure of less than 1,013 hPa and above the boiling point of the organic compound to obtain a conductive film. As a result, a hydrocarbon compound is formed on the MXene layer, and oxidation of the MXene layer is suppressed, so a conductive film with good conductivity stability is obtained.

[0125] The pressure during heating described above is less than 1,013 hPa as an absolute pressure, preferably 1,000 hPa or less, more preferably 50 hPa to 1,000 hPa, and even more preferably 100 hPa to 1,000 hPa. It is believed that this pressure range allows the MXene layer to be maintained and facilitates the formation of hydrocarbon compounds.

[0126] The heating temperature is above the boiling point of the organic compound, preferably 200°C or higher, more preferably 200°C to 400°C, and even more preferably 200°C to 350°C. It is believed that this temperature range allows the layered structure of MXene to be maintained and facilitates the formation of hydrocarbon compounds.

[0127] The heating time is preferably 1 hour to 30 hours, and more preferably 5 hours to 20 hours.

[0128] Pre-drying may be performed before the above heating. Such pre-drying can be carried out under normal pressure at a temperature of 80°C or lower. The pressure during pre-drying may be preferably 900 hPa to 1,200 hPa as absolute pressure, and more preferably 950 hPa to 1,160 hPa as absolute pressure. The temperature during pre-drying may be 10°C or lower, preferably 10°C to 80°C, more preferably 20°C to 70°C, and even more preferably 30°C to 70°C. The pre-drying time is, for example, 30 minutes to 10 hours, preferably 1 hour to 5 hours.

[0129] The above precursor film is prepared in the following steps (h) or (f1): (h) Forming a precursor film using a mixture containing the above-mentioned precursor particles and the above-mentioned organic compound, (f1) Form a dry film using a dispersion containing the above precursor particles, and impregnate the dry film with the above organic compound. It can be manufactured by one of the following.

[0130] The following describes each step.

[0131] ·Process (h) The mixed solution containing the above-mentioned precursor particles and the above-mentioned organic compound may be the mixture of the delamination product obtained in step (f) and the above-mentioned organic compound as is, or a mixed solution may be used in which precursor particles that can be produced by any method are mixed with the above-mentioned organic compound.

[0132] In the above-mentioned mixture, the content of precursor particles may be, for example, 0.5% by mass or more and 10% by mass or less, and more specifically, 1% by mass or more and 5% by mass or less, out of 100% by mass of the total amount of the mixture.

[0133] The above mixture may contain other dispersion media in addition to the above organic compound. Examples of other dispersion media include water. The organic compound and the other dispersion media may be mixed such that the volume ratio (organic compound / other dispersion media) is, for example, 50 / 50 or more, preferably 55 / 45 or more.

[0134] The above mixture may further contain the above resin as needed.

[0135] The formation of the above precursor film can be carried out, for example, by suction filtration of the above mixture, or by coating the mixture and drying it under normal pressure one or more times.

[0136] One method for applying the above-mentioned mixture is, for example, by spraying. The spraying method may be, for example, an airless spraying method or an air spraying method, and specifically, a method of spraying using a nozzle such as a one-fluid nozzle, a two-fluid nozzle, or an airbrush.

[0137] ·Process (f1) As the dispersion containing the above-mentioned precursor particles, the delamination product obtained by step (f) above may be used as is, or a dispersion in which precursor particles that can be produced by any method are dispersed in a dispersion medium may be used.

[0138] Examples of the above-mentioned dispersion media include water; N-methylpyrrolidone, N-methylformamide, N,N-dimethylformamide, methanol, ethanol, dimethyl sulfoxide, ethylene glycol, acetic acid, and other organic media.

[0139] The content of the above-mentioned precursor particles may be, for example, 0.5% to 10% by mass, and more specifically, 1% to 5% by mass, out of 100% by mass of the total amount of the dispersion.

[0140] The formation of the above-mentioned dry film can be carried out by suction filtration of the dispersion, or by applying the dispersion and drying it under atmospheric pressure one or more times. A method for applying the dispersion is to apply it by spraying. The spraying method may be, for example, an airless spraying method or an air spraying method, and specifically, a method of spraying using a nozzle such as a one-fluid nozzle, a two-fluid nozzle, or an airbrush.

[0141] The penetration of the above-mentioned organic compound into the above-mentioned dried film can typically be carried out by immersing the dried film in the above-mentioned organic compound.

[0142] One application of the film of this embodiment is electrodes. Such electrodes only need to contain the conductive film described above, and are not limited to any specific form. Electrodes can range from solid to flexible.

[0143] In the electrode of this embodiment, the film may be exposed to the outside air so as to be in direct contact with the object to be measured, or it may be covered with a substrate and / or a protective film.

[0144] If the electrode of this embodiment has a substrate, the film and the substrate may be in direct contact. The material of the substrate is not particularly limited and may be an inorganic material such as ceramic or glass, or an organic material. Examples of such organic materials include flexible organic materials, specifically thermoplastic polyurethane elastomer (TPU), PET film, polyimide film, etc. The material of the substrate may also be a fibrous material such as paper or cloth (for example, a sheet-like fibrous material).

[0145] The protective layer described above may be a layer that covers at least a part or all of the film, and preferably a layer that covers at least a part of the film. The protective layer may be an organic material, and specifically may be a resin such as acrylic resin, polyester resin, polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, polycarbonate resin, polyurethane resin, polystyrene resin, polyether resin, polylactic acid, or polyvinyl alcohol.

[0146] The electrodes described above can be used for any suitable application. Examples include counter electrodes and reference electrodes for electrochemical measurements, electrodes for electrochemical capacitors, electrodes for batteries, bioelectrodes, electrodes for sensors, electrodes for antennas, and electrodes for electrical stimulation. They can also be used in applications requiring high conductivity (reducing the decrease in initial conductivity and preventing oxidation), such as electromagnetic shielding (EMI shielding). Details of these applications are described below.

[0147] The electrodes are not particularly limited, but may include, for example, electrodes for capacitors, electrodes for batteries, electrodes for biosignal sensing, electrodes for sensors, electrodes for antennas, and electrodes for electrical stimulation. By using the above-mentioned membrane, large-capacity capacitors and batteries, low-impedance biosignal sensing electrodes, and highly sensitive sensors and antennas can be obtained even in a smaller volume (device occupied volume).

[0148] A capacitor can be an electrochemical capacitor. An electrochemical capacitor is a capacitor that utilizes the capacitance that arises from a physicochemical reaction between electrodes (electrode active material) and ions in an electrolyte (electrolyte ions), and can be used as a device for storing electrical energy (energy storage device). A battery can be a chemical battery that can be repeatedly charged and discharged. A battery can be, for example, a lithium-ion battery, a magnesium-ion battery, a lithium-sulfur battery, a sodium-ion battery, etc., but is not limited to these.

[0149] Biosignal sensing electrodes are electrodes used to acquire biological signals. Biosignal sensing electrodes may, but are not limited to, electrodes used to measure EEG (electroencephalography), ECG (electrocardiogram), EMG (electromyography), and EIT (electrical impedance tomography).

[0150] Sensor electrodes are electrodes used to detect a target substance, state, abnormality, etc. Sensors may include, but are not limited to, gas sensors or biosensors (chemical sensors that utilize molecular recognition mechanisms of biological origin).

[0151] Antenna electrodes are electrodes that radiate electromagnetic waves into space and / or receive electromagnetic waves in space. The antennas that antenna electrodes make up are not particularly limited and include antennas for mobile communications such as mobile phones (so-called 3G, 4G, and 5G antennas), antennas for RFID, or antennas for NFC (Near Field Communication).

[0152] Electrical stimulation electrodes are electrodes used to apply electrical stimulation to living organisms. Such electrical stimulation can be applied to living organisms, particularly to living tissues, such as the spinal cord, brain, nerve tissue, and muscle tissue, but is not limited to these.

[0153] The two-dimensional particles, their manufacturing method, and conductive film in one embodiment of this disclosure have been described in detail above, but various modifications are possible. It should be noted that the two-dimensional particles and conductive film of this disclosure may be manufactured by a method different from the manufacturing method in the above-described embodiment, and the manufacturing method of the two-dimensional particles and conductive film of this disclosure is not limited to the one that provides the two-dimensional particles and conductive film in the above-described embodiment.

[0154] This disclosure includes the following: <1> It comprises one or more layers and a hydrocarbon compound. The aforementioned layer is given by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an iodine atom, an oxygen atom, a chlorine atom, a phosphorus atom, and a hydrogen atom), The hydrocarbon compound is a two-dimensional particle present on the layer. <2> The hydrocarbon compound includes hydrocarbon compounds having 3 to 10 carbon atoms. <1> The two-dimensional particle described above. <3> The carbon content derived from the hydrocarbon compound is 0.5% by mass or more out of 100% by mass of the total amount of two-dimensional particles. <1> or <2> The two-dimensional particle described above. <4> Further comprising one or more metal atoms selected from Li, K, Na, Mg, Mn, Ca, Fe, Zn, Al, and Cu, <1> ~ <3> A two-dimensional particle described in any one of the following. <5> <1> ~ <4> A conductive film containing two-dimensional particles as described in any one of the above, and having an electrical conductivity of 2,000 S / cm or more. <6> The method includes heating precursor particles in the presence of an organic compound under conditions of an absolute pressure of less than 1,013 hPa and above the boiling point of the organic compound to obtain two-dimensional particles. The aforementioned precursor particles are It contains one terra layer, The aforementioned layer is given by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an iodine atom, an oxygen atom, a chlorine atom, a phosphorus atom, and a hydrogen atom), A method for producing two-dimensional particles, wherein the melting point of the organic compound is 20°C or lower. <7> The aforementioned organic compound includes an organic compound having one or more of the following groups: carbonyl group, ester group, amide group, formamide group, carbamoyl group, carbonate group, aldehyde group, ether group, sulfonyl group, sulfinyl group, hydroxyl group, cyano group, and nitro group. <6> A method for producing two-dimensional particles as described above. <8> The relative permittivity of the aforementioned organic compound is 60 or higher. <6> or <7> A method for producing two-dimensional particles as described above. <9> The aforementioned precursor particles are (a) The following formula: M m AX n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. A is at least one element from groups 12, 13, 14, 15, or 16. n is between 1 and 4, m is greater than n and less than or equal to 5. Prepare a precursor represented by (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Mix the above-mentioned etched material with an intercalator to obtain an intercalated material. (d) Stirring the intercalation product to obtain a delamination product containing precursor particles. Manufactured by a manufacturing method that includes, <6> ~ <8> A method for producing two-dimensional particles as described in any one of the following. [Examples]

[0155] The present invention will be further described in detail by the following examples, but the present invention is not limited thereto.

[0156] [Example 1] [Fabrication of 2D particles] In Example 1, a conductive film containing two-dimensional particles was fabricated by sequentially performing the following steps, as detailed below: (1) preparation of the precursor (MAX), (2) etching of the precursor, (3) washing, (4) intercalation, (5) delamination and washing, (6) mixing with N-methylformamide, and (7) preparation and heating of the precursor film.

[0157] (1) Preparation of the precursor (MAX) TiC powder, Ti powder, and Al powder (all manufactured by Kojun Chemical Laboratory Co., Ltd.) were placed in a ball mill containing zirconia balls in a molar ratio of 2:1:1 and mixed for 24 hours. The resulting mixed powder was calcined at 1350°C for 2 hours under an Ar atmosphere. The resulting calcined body (block) was then pulverized with an end mill to a maximum size of 40 μm or less. This yielded Ti3AlC2 particles as MAX particles.

[0158] (2) Etching of the precursor (ACID method) Using the Ti3AlC2 particles (powder) prepared by the above method, etching was performed under the following etching conditions to obtain a solid-liquid mixture (slurry) containing solid components derived from the Ti3AlC2 powder. (Etching conditions) • Precursor: Ti3AlC2 (passed through a sieve with a mesh size of 45 μm) • Etching solution composition: 49% HF 6 mL H2O 18mL HCl (12M) 36mL • Amount of precursor added: 3.0g • Etching container: 100mL iBoy Etching temperature: 35℃ Etching time: 24 hours • Stirrer rotation speed: 400 rpm

[0159] (3) Washing The slurry was divided into two portions and placed into two 50 mL centrifuge tubes. Centrifugation was performed at 3500 G using a centrifuge, and the supernatant was discarded. 40 mL of pure water was added to the remaining precipitate in each centrifuge tube, and the process of separating and removing the supernatant was repeated 11 times by centrifugation at 3500 G. After the final centrifugation, the supernatant was discarded, and Ti3C2T was extracted. x - A water-based clay was obtained.

[0160] (4) Intercalation The above Ti3C2T s Li intercalation was performed on clay with a water medium using LiCl as the Li-containing compound, stirring at 20°C to 25°C for 12 hours, under the following conditions. (Conditions for intercalation of Li) ·Ti3C2T x - Moisture-based clay (MXene after washing): Solid content 0.75g LiCl: 0.75g ·Pure water: 37.2g Intercalation container: 100mL iBoy ·Temperature: 20℃ or higher and 25℃ or lower (room temperature) ·Time: 10h • Stirrer rotation speed: 800 rpm

[0161] (5) Delamination and washing The above Ti3C2T x - To the water medium clay, (i) 40 mL of pure water was added and stirred in a shaker for 15 minutes, then (ii) centrifuged at 3,500 G, and (iii) the supernatant was collected as a single layer MXene-containing liquid. This procedure (i) to (iii) was repeated a total of four times to obtain a single layer MXene-containing supernatant. Furthermore, this supernatant was centrifuged using a centrifuge at 4,300 G for 2 hours, and the supernatant was discarded to obtain clay containing delamination material.

[0162] (6) Mixture with N-methylformamide A mixture of 55 parts by volume of N-methylformamide and 45 parts by volume of water was prepared as a mixed dispersion medium. The delamination material and the mixed dispersion medium were then mixed so that the content of the delamination material in the resulting mixture was 1.5% by mass. Subsequently, this mixture was dispersed for 15 minutes using an ultrasonic cleaner (AS ONE Corporation, AS482) to obtain a slurry containing two-dimensional particles.

[0163] (7) Preparation and heating of the precursor film A predetermined amount of the slurry containing the above two-dimensional particles was placed in a 50 mL centrifuge tube, and pure water was added. At this time, the amount of pure water added was adjusted so that the concentration of the delamination treatment in the mixture was 1.5% by mass. Then, the mixture was stirred in a shaker for 15 minutes to obtain the slurry.

[0164] A filtration membrane was prepared by suction filtration of the slurry. A membrane filter (Merck Durapore, pore size 0.45 μm) was used for suction filtration. The filtration membrane was dried in a vacuum oven at 150°C for 16 hours to prepare a precursor membrane.

[0165] The obtained precursor film was placed in a vacuum oven and heated for 12 hours under conditions of absolute pressure 912 hPa (gauge pressure -0.1 MPa) and 200°C to produce a film.

[0166] [Comparative Example 1] [Fabrication of 2D particles] In Comparative Example 1, (1) preparation of the precursor (MAX), (2) etching of the precursor, (3) washing, (4) intercalation, and (5) delamination and washing were performed in the same manner as in Example 1 to obtain a delaminate product, and then the following step (7) was performed to produce two-dimensional particles. The preparation and heating of the precursor film were performed in order to produce a conductive film containing two-dimensional particles. (7) Preparation and heating of the precursor film A predetermined amount of delamination material was placed in a 50 mL centrifuge tube, and pure water was added. At this time, the amount of pure water added was adjusted so that the concentration of the delamination material in the mixture was 1.5% by mass. Then, the mixture was stirred in a shaker for 15 minutes to obtain a slurry.

[0167] A filtration membrane was prepared by suction filtration of the slurry. A membrane filter (Merck Durapore, pore size 0.45 μm) was used for suction filtration. The filtration membrane was dried in a vacuum oven at 150°C for 16 hours to prepare a precursor membrane.

[0168] The obtained film was placed in a vacuum oven and heated for 12 hours under conditions of absolute pressure 912 hPa (gauge pressure -0.1 MPa) and 200°C to produce a film.

[0169] [Gas Chromatography - Mass Spectrometry] Using a virolyzer (Frontier Labs "PY-2020i"), the two-dimensional particles obtained in the examples and comparative examples were heated to 450°C to desorb the gas adsorbed on the surface of the two-dimensional particle layer. The gas desorbed from the two-dimensional particles was subjected to mass spectrometry using a gas chromatography-mass spectrometer (Agilent Technologies, Inc. "7890A / 5975C").

[0170] [Carbon and sulfur analysis] Using a carbon-sulfur analyzer (Horiba, Ltd., "EMIA-920V2 / FA"), the total carbon content in the two-dimensional particles was calculated by qualitatively and quantitatively analyzing the CO and CO2 generated when the two-dimensional particles obtained in the examples and comparative examples were heated in an oxygen stream together with combustion aids (metal W, metal Sn). The weight of the two-dimensional particles used for measurement was divided by the formula weight of Ti3C2O2 and multiplied by the formula weight of C2 to obtain the value representing the carbon atom content originating from the layers of the two-dimensional particles. The carbon atom content originating from the layers of the two-dimensional particles was calculated by subtracting the carbon atom content originating from the layers of the two-dimensional particles from the total carbon atom content of the two-dimensional particles.

[0171] [X-ray photoelectron spectroscopy] X-ray photoelectron spectroscopy analysis was performed on the conductive films obtained in the examples and comparative examples using an X-ray photoelectron spectroscopy analyzer (ULVAC-PHI, Inc., "PHI Quantes") under the following conditions. Then, based on the obtained spectra, the ratio of the area of ​​peaks attributed to divalent and trivalent Ti to the total area of ​​peaks attributed to Ti2p was calculated. [X-ray photoelectron spectroscopy measurement conditions] X-ray source: Al monochromatic Kα (25W, 15kV) Analysis range: 100 μmφ Photoelectron extraction angle: 45° relative to the sample surface

[0172] [Measurement of electrical conductivity] The conductivity of the obtained conductive film was determined. For each sample, resistivity (Ω) and thickness (μm) were measured at three locations, and the conductivity (S / cm) was calculated from these measurements. The average of the three conductivity values ​​obtained was then adopted. For resistivity measurement, a simple low-resistivity meter (Loresta AX MCP-T370, Mitsubishi Chemical Analytical Corporation) was used to measure the surface resistance of the film using the four-terminal method. For thickness measurement, a micrometer (MDH-25MB, Mitutoyo Corporation) was used. The volume resistivity was calculated from the obtained surface resistance and film thickness, and the conductivity was determined by taking the reciprocal of that value.

[0173] [Heat treatment] The two-dimensional particles obtained in the examples and comparative examples were heat-treated at 300°C for 2 hours under normal pressure and in air.

[0174] [Table 1]

[0175] Example 1 is an example of the present disclosure, and it was confirmed that the two-dimensional particles contain hydrocarbon compounds. Furthermore, it was confirmed that the conductivity of the conductive film obtained using such two-dimensional particles was increased before and after heat treatment at 300°C, and in particular, that the decrease in conductivity was suppressed even in high-temperature environments, and in some cases, the conductivity could be increased.

[0176] Comparative Example 1 is an example in which two-dimensional particles and a conductive film were fabricated without using N-methylformamide. It was confirmed that the conductivity tended to decrease, and in particular, the conductivity decreased under high-temperature conditions. [Explanation of Symbols]

[0177] 1a, 1b layer body (M m X n layer) 3a, 5a, 3b, 5b Modifier or Terminus T 7a, 7b MXene layer 10, 10a, 10b MXene particles (two-dimensional particles of layered material)

Claims

1. It comprises one or more layers and a hydrocarbon compound. The aforementioned layer is given by the following formula: M ｍ X ｎ (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal,) X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an iodine atom, an oxygen atom, a chlorine atom, a phosphorus atom, and a hydrogen atom), The hydrocarbon compound is a two-dimensional particle present on the layer.

2. The two-dimensional particle according to claim 1, wherein the hydrocarbon compound comprises a hydrocarbon compound having 3 to 10 carbon atoms.

3. The two-dimensional particle according to claim 1, wherein the carbon content derived from the hydrocarbon compound is 0.5% by mass or more of the total amount of the two-dimensional particle by mass.

4. The two-dimensional particle according to claim 1, further comprising one or more metal atoms selected from Li, K, Na, Mg, Mn, Ca, Fe, Zn, Al, and Cu.

5. A conductive film comprising two-dimensional particles according to any one of claims 1 to 4, wherein the conductivity is 2,000 S / cm or more.

6. The method includes heating precursor particles in the presence of an organic compound under conditions of an absolute pressure of less than 1,013 hPa and above the boiling point of the organic compound to obtain two-dimensional particles. The aforementioned precursor particles are It includes one or more layers, The aforementioned layer is given by the following formula: M ｍ X ｎ (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal,) X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an iodine atom, an oxygen atom, a chlorine atom, a phosphorus atom, and a hydrogen atom), A method for producing two-dimensional particles, wherein the melting point of the organic compound is 20°C or lower.

7. The method for producing two-dimensional particles according to claim 6, wherein the organic compound comprises an organic compound having one or more of the following groups: carbonyl group, ester group, amide group, formamide group, carbamoyl group, carbonate group, aldehyde group, ether group, sulfonyl group, sulfinyl group, hydroxyl group, cyano group, and nitro group.

8. The method for producing two-dimensional particles according to claim 6, wherein the relative permittivity of the organic compound is 60 or more.

9. The aforementioned precursor particles are (a) The following formula: M ｍ AX ｎ (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal,) X is a carbon atom, a nitrogen atom, or a combination thereof. A is at least one element from groups 12, 13, 14, 15, or 16. n is between 1 and 4, m is greater than n and less than or equal to 5. Prepare a precursor represented by (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) Mixing the above-mentioned etched material with an intercalator to obtain an intercalated material. (d) Stirring the intercalation product to obtain a delamination product containing precursor particles. A method for producing two-dimensional particles according to any one of claims 6 to 8, which is produced by a manufacturing method including the above.

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