Two-dimensional particle-containing composition and method for producing a two-dimensional particle-containing composition

Abstract

The present invention provides a two-dimensional particle-containing composition and a method for producing the two-dimensional particle-containing composition. [Solution] A two-dimensional particle of a layered material comprising one or more layers, and a dispersion medium having a relative permittivity greater than that of water, wherein the one or more layers are of the following formula: M m X n A two-dimensional particle-containing composition comprising a layer body represented by the formula (wherein M is at least one metal element M1 of groups 3, 4, 5, 6, or 7 having an ionization energy higher than Ti, or a combination of metal element M1 accounting for 50 atomic percent or more of M and metal element M2 of groups 3, 4, 5, 6, or 7 other than metal element M1 accounting for 50 atomic percent or less of M, X is a carbon atom, a nitrogen atom, or a combination thereof, n is between 1 and 4, and m is greater than n and 5 or less), and a predetermined modification or termination T present on the surface of the layer body, wherein the two-dimensional particles have fluorine and oxygen elements.

Description

[Technical Field]

[0001] This disclosure relates to a two-dimensional particle-containing composition and a method for producing a two-dimensional particle-containing composition. [Background technology]

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

[0003] Currently, various studies are being conducted to explore the application of MXene to a wide range of fields. For example, its use is being considered in applications that require maintaining high conductivity, such as electrodes and electromagnetic shielding (EMI shielding) in electrical devices. As part of these studies, Non-Patent Document 1, for instance, presents the results of a systematic study of the EMI shielding characteristics of 16 types of MXene. In particular, it shows that the EMI shielding characteristics can be controlled by changing the elemental ratio of the solid solution MXene. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Beyond Ti3C2Tx: MXenes for Electromagnetic Interference Shielding, ACS Nano 2020,14,4,5008-5016 [Overview of the project] [Problems that the invention aims to solve]

[0005] Depending on the application, a film with a sufficiently high oxidation resistance containing MXene may be required, and the film may be formed using an MXene-containing composition such as a dispersion containing MXene. However, with the technique shown in Non-Patent Document 1, it is difficult to obtain a dispersion in which MXene is well dispersed, and as a result, it is also difficult to obtain a film with a sufficiently high oxidation resistance containing MXene. **Means for Solving the Problems**

[0006] According to one gist of the present invention, A two-dimensional particle-containing composition comprising two-dimensional particles of a layered material including one or more layers and a dispersion medium having a relative permittivity greater than that of water, where the one or more layers have the following formula: M m X n (In the formula, M is at least one metal element M1 of Groups 3, 4, 5, 6, and 7 having an ionization energy higher than that of Ti, or a combination of a metal element M1 of Groups 3, 4, 5, 6, and 7 other than the metal element M1, which accounts for 50 atomic% or more in M, and a metal element M2 of Groups 3, 4, 5, 6, and 7 other than the metal element M1, which accounts for 50 atomic% or less in M, 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 main 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 oxygen atom, and a hydrogen atom) present on the surface of the layer main body, A two-dimensional particle-containing composition is provided in which the two-dimensional particles have a fluorine element and an oxygen element.

[0007] According to another gist of the present invention, (a) The following formula: M m AX n (In the formula, M is It is at least one metallic element M1 from groups 3, 4, 5, 6, or 7 whose ionization energy is higher than that of Ti. This is a combination of a metallic element M1 that accounts for 50 atomic percent or more of M, and a metallic element M2 from groups 3, 4, 5, 6, or 7 other than metallic element M1 that accounts for 50 atomic percent or less of M. 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) Performing an etching treatment to remove at least some A atoms from the precursor using an etching solution containing a metal compound containing a metal cation and a fluoride, and an intercalation treatment of the metal cation, (c) Wash the processed product obtained by the etching process and the intercalation process with water to obtain a water-washed product. (d) Mixing the water-washed material with a dispersion medium having a dielectric constant greater than that of water, intercalating the dispersion medium, and obtaining an intercalated material, (e) Using the intercalation-treated material, perform delamination in the presence of a dispersion medium with a relative permittivity greater than that of water. A method for producing a two-dimensional particle-containing composition is provided. [Effects of the Invention]

[0008] According to this disclosure, the metal elements constituting one or more layers in the two-dimensional particles (MXene particles) of the layered material in the MXene-containing composition are mainly composed of metal elements having a higher ionization energy than Ti, and the composition contains a dispersion medium with a relative permittivity greater than that of water. This provides a two-dimensional particle-containing composition with high dispersibility and high oxidation resistance. Furthermore, a manufacturing method for easily producing the two-dimensional particle-containing composition is provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view of MXene, which constitutes the two-dimensional particles of the layered material contained in the two-dimensional particle-containing composition of this embodiment. [Modes for carrying out the invention]

[0010] (Embodiment 1: Two-dimensional particle-containing composition) The following describes in detail a two-dimensional particle-containing composition in one embodiment of the present disclosure, but the present disclosure is not limited to this embodiment.

[0011] The two-dimensional particle-containing composition in this embodiment is The mixture comprises two-dimensional particles of a layered material containing one or more layers, and a dispersion medium with a relative permittivity greater than that of water. The one or more layers described above are defined by the following formula: M m X n (In the formula, M is It is at least one metallic element M1 from groups 3, 4, 5, 6, or 7 whose ionization energy is higher than that of Ti. This is a combination of a metallic element M1 that accounts for 50 atomic percent or more of M, and a metallic element M2 from groups 3, 4, 5, 6, or 7 other than metallic element M1 that accounts for 50 atomic percent or less of M. 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 (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) present on the surface of the layer body, The two-dimensional particles contain fluorine and oxygen. The two-dimensional particle-containing composition exhibits high dispersibility and high oxidation resistance because the two-dimensional particles contain a metal element that exhibits a higher ionization energy than Ti, and a dispersion medium with a relative permittivity greater than that of water.

[0012] The above-mentioned layered material can be understood as a layered compound and is also represented as "M m X n T s ", where s is an arbitrary number, and conventionally, x or z may be used instead of s. Typically, n can be, but is not limited to, 1, 2, 3, or 4.

[0013] In the above formula of MXene, M is at least one metal element M1 of Groups 3, 4, 5, 6, 7 having an ionization energy higher than that of Ti, or a combination of a metal element M1 accounting for 50 atomic% or more in the proportion of M and a metal element M2 of Groups 3, 4, 5, 6, 7 other than the metal element M1 accounting for 50 atomic% or less in the proportion of M. In this embodiment, in order to obtain a two-dimensional particle-containing composition with more excellent oxidation resistance, it was first found that the metal elements constituting the layered material should be such that the metal elements having an ionization energy higher than that of Ti account for more than half. Examples of at least one metal element M1 of Groups 3, 4, 5, 6, 7 having an ionization energy higher than that of Ti include one or more metal elements selected from the group consisting of V, Nb, and Mo. As one of the preferred forms, it can be mentioned that M is composed of at least one M1 selected from the group consisting of V, Nb, and Mo.

[0014] As the MXene according to this embodiment, the above formula: M m X n is represented as follows. Sc2C, Zr2C, Zr2N, Hf2C, Hf2N, V2C, V2N, Nb2C, Ta2C, Cr2C, Cr2N, Mo2C, Mo 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" respectively mean about 1.3 (= 4 / 3) and about 0.6 (= 2 / 3).), Zr3C2, (Ti,V)3C2, Hf3C2, (Hf2V)C2, (Hf2Mn)C2, (V2Ti)C2, (Mo2Sc)C2, (Mo2Ti)C2, (Mo 2Zr)C2, (Mo2Hf)C2, (Mo2V)C2, (Mo2Nb)C2, (Mo2Ta)C2, (W2Ti)C2, (W2Zr)C2, (W2Hf)C2, V4C3, Nb4C3, Ta4C3, (Ti,Nb)4C3, (Nb,Zr)4C3, (Ti2Nb2)C3, (Ti2Ta2)C3, (V2Ti2)C3, (V2Nb2)C3, (V2Ta2)C3, (Nb2Ta2)C3, (Cr2V2)C3, (Cr2 Nb2)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.)

[0015] The layer body of the two-dimensional particles is preferably V2C, V4C3, and Mo2Ti2C3.

[0016] Furthermore, if the layer itself contains Ti as a metallic element, it is preferable that the outermost layer of M atoms among the multiple layers of M atoms constituting the layer itself is a layer of a metallic element other than Ti, and the inner layers of M atoms sandwiched between the outermost M atom layers are layers of a metallic element containing Ti.

[0017] In this embodiment, MXene may contain a relatively small amount of residual A atoms, for example, 10% by mass or less relative to the original A atoms. The residual amount of A atoms is preferably 8% by mass or less, more preferably 6% by mass or less. 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 electrode.

[0018] In the following, the two-dimensional particles (also referred to as "MXene particles") in the two-dimensional particle-containing composition according to this embodiment will be described with reference to Figure 1.

[0019] The two-dimensional particles of this embodiment are an aggregate containing one layer of MXene10a (single-layer MXene), schematically illustrated in Figure 1(a). More specifically, MXene10a 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.

[0020] The particles of the layered material according to this embodiment may include multiple layers along with one layer. As an example of multiple layered MXene (multilayer MXene), two layers of MXene 10b are shown schematically in Figure 1(b), but the material is not limited to these examples. 1b, 3b, 5b, and 7b in Figure 1(b) are the same as 1a, 3a, 5a, and 7a in Figure 1(a) described above. Two adjacent MXene layers of multilayer MXene (e.g., 7a and 7b) do not necessarily have to be completely separated, but may be partially in contact. The MXene 10a may be a single layer formed by the individual separation of the multilayer MXene 10b, while unseparated multilayer MXene 10b may remain, resulting in a mixture of single-layer MXene 10a and multilayer MXene 10b. Even when multilayer MXene is included, it is preferable that the multilayer MXene is an MXene with a small number of layers obtained through a delamination process. "Small number of layers" means, for example, that the number of MXene layers is 10 or less. Hereafter, this "multilayer MXene with a small number of layers" may be referred to as "low-layer MXene." The thickness of low-layer MXene in the stacking direction is preferably 15 nm or less, and more preferably 10 nm or less. Also, single-layer MXene and low-layer MXene are sometimes collectively referred to as "single-layer / low-layer MXene."

[0021] In this embodiment, it is preferable that the layered material particles contain a large amount of single-layer and thin-layer MXene. By containing a large amount of single-layer and thin-layer MXene, the specific surface area of ​​MXene can be made larger than that of multilayer MXene, and as a result, the conductivity can be improved, for example. In this embodiment, the particles of the layered material have 10 layers or less of MXene stacking and a thickness of 15 nm or less, preferably 10 nm or less, and the proportion of single-layer and thin-layer MXene to the total MXene is preferably 80 volume% or more, more preferably 90 volume% or more, and even more preferably 95 volume% or more. Furthermore, it is more preferable that the volume of single-layer MXene is greater than the volume of thin-layer MXene. Since the true density of these MXene does not vary greatly depending on the form in which they exist, it can also be said that it is more preferable that the mass of single-layer MXene is greater than the mass of thin-layer MXene. When these relationships are met, the specific surface area can be further increased, and for example, the deterioration of conductivity over time can be further suppressed. Most preferably, the particles of the layered material in this embodiment are formed only of single-layer MXene.

[0022] Although not limited to this embodiment, the thickness of each MXene layer (corresponding to the MXene layers 7a and 7b described above) can be, for example, 1 nm or more and 30 μm or less, for example, 1 nm or more and 5 nm or less, or even 1 nm or more and 3 nm or less (this mainly depends on the number of M atomic layers contained in each layer). For each laminate of the multilayer MXene that may be included, the interlayer distance (or void dimension, shown as Δd in Figure 1(b)) 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.

[0023] (Fluorine and oxygen) The aforementioned two-dimensional particles have fluorine and oxygen elements on their surface. Having fluorine and oxygen elements means that these elements are bonded or adsorbed to the surface of MXene, for example, in the form of ions. When two-dimensional particles have fluorine and oxygen elements with small atomic radii, for example, when oxygen and fluorine elements with small atomic radii are present on the surface of the main layer constituting MXene, the interlayer distance becomes narrower, the structure becomes more stable and oxidation resistance is increased, and moisture absorption due to the insertion of water molecules between layers is suppressed, resulting in high moisture resistance. The presence of the above fluorine and oxygen atoms on the two-dimensional particles can be confirmed by XPS.

[0024] (One or more selected from the group consisting of Li ions, Na ions, and K ions) Preferably, the two-dimensional particles further contain one or more selected from the group consisting of Li ions, Na ions, and K ions. These metal cations may be derived from metal compounds containing metal cations, which are used for intercalation of the metal cations in the manufacturing process of the two-dimensional particle-containing composition. It is believed that by using these metal cation compounds for intercalation in the manufacturing process, for example, monolayer formation is facilitated, the structure of the two-dimensional particles is stabilized, and oxidation resistance is further improved.

[0025] The proportion of two-dimensional particles (MXene content) in the two-dimensional particle-containing composition is not particularly limited. For example, the MXene content in the composition can be 0.01% by mass or more in terms of solid content. Conventionally, it has been difficult to form compositions with two-dimensional particles because they are difficult to disperse. However, according to the two-dimensional particle-containing composition of this embodiment, the two-dimensional particles disperse easily in a dispersion medium with a dielectric constant greater than that of water, so a composition with high dispersion of two-dimensional particles can be obtained. By using this highly dispersed two-dimensional particle-containing composition for example in film formation, conductive films requiring thickness, such as for electrode applications, can be manufactured with high productivity. For example, in order to form a thick film, the proportion of two-dimensional particles in the two-dimensional particle-containing composition can be set to 1% by mass or more in terms of solid content. The proportion of two-dimensional particles in the two-dimensional particle-containing composition may be further set to 1.5% by mass or more in terms of solid content. Considering the dispersibility of two-dimensional particles, the upper limit of the proportion of two-dimensional particles in the two-dimensional particle-containing composition is, for example, 10% by mass in terms of solid content.

[0026] (dispersion medium) Conventionally, TMAOH has been used in the manufacturing process of MXene to create a single layer. However, TMAOH tends to remain in MXene, leading to a decrease in properties, including oxidation resistance. Furthermore, since TMAOH exhibits strong basicity, it is desirable to manufacture MXene without using TMAOH from the standpoint of work safety. In light of these circumstances, after careful consideration, in the two-dimensional particle-containing composition according to this embodiment, a dispersion medium with a relative permittivity greater than that of water is used as the dispersion medium for dispersing the two-dimensional particles. In a dispersion medium with a relative permittivity greater than that of water, the charge of the two-dimensional particles (MXene particles) becomes more stable, resulting in higher dispersibility. Due to this high dispersion stability, a two-dimensional particle-containing composition with a high content can be realized without the two-dimensional particles (MXene particles) agglomerating. The relative permittivity of water is 80.4 at 20°C, and the dispersion medium for dispersing the two-dimensional particles only needs to have a relative permittivity greater than that of water at 20°C. For example, a dispersion medium with a relative permittivity greater than 80, or even 100 or more, can be used. In the following, a dispersion medium with a relative permittivity greater than that of water may be referred to as a "high relative permittivity dispersion medium." In a preferred embodiment, the two-dimensional particle-containing composition of this embodiment does not contain TMAOH, which has been used conventionally.

[0027] Examples of dispersion media with a dielectric constant greater than that of water include N-methylformamide (NMF, dielectric constant: 171) and N-methylacetamide (NMAc, dielectric constant: 179), and one or more of these can be used.

[0028] In this embodiment, a mixed dispersion medium of a high dielectric constant dispersion medium and another dispersion medium may be used, provided that the dielectric constant is greater than that of water. A preferred dispersion medium is one containing at least one of the high dielectric constant dispersion mediums N-methylformamide and N-methylacetamide. More preferably, the dispersion medium contains at least one of N-methylformamide and N-methylacetamide in an amount of 50% by volume or more. Other dispersion media include dispersion media with a dielectric constant of 10 or more, such as aqueous dispersion media and organic dispersion media. A typical aqueous dispersion medium is water, and in some cases, an aqueous solution containing a relatively small amount of another liquid substance in addition to water (for example, 30% by mass or less on a total basis, preferably 20% by mass or less). Examples of organic dispersion media include acetonitrile (dielectric constant: 38), N,N-dimethylacetamide (dielectric constant: 38), N,N-dimethylformamide (dielectric constant: 37), DMSO (dielectric constant: 47), DMF (dielectric constant: 37), NMP (dielectric constant: 32), acetone (dielectric constant: 20), 2-methyl-2-propanol (dielectric constant: 10), isopropyl alcohol (dielectric constant: 18), ethanol (dielectric constant: 25), and alcohols including methanol (dielectric constant: 33). It is preferable to include NMF, which has a high dielectric constant, as a dispersion medium with a dielectric constant greater than that of water, and most preferably the dispersion medium consists of NMF.

[0029] (Additives) The two-dimensional particle-containing composition according to this embodiment may contain additives other than the two-dimensional particles and dispersion medium, such as amines including tetramethylammonium hydroxide, hexylamine, and octylamine, polyphosphate, and sodium ascorbate. The proportion of additives in the composition is not particularly limited, but from the viewpoint of increasing the concentration of two-dimensional particles, for example, the proportion of additives in the composition should be kept to 10% by mass or less.

[0030] (Form of composition) Examples of two-dimensional particle-containing compositions according to this embodiment include inks, pastes, slurries, and the like.

[0031] One embodiment of the aforementioned paste is a conductive paste made of a composite material containing a polymer. The mass ratio of two-dimensional particles (particles of layered material) in the conductive paste is, for example, 50% or more. The aforementioned polymer is, for example, a hydrophilic polymer (including those that exhibit hydrophilicity by blending a hydrophilic additive with a hydrophobic polymer, and those whose surfaces, such as hydrophobic polymers, have been treated to make them hydrophilic), and the hydrophilic polymer preferably contains one or more selected from the group consisting of polysulfone, cellulose acetate, regenerated cellulose, polyethersulfone, water-soluble polyurethane, polyvinyl alcohol, sodium alginate, acrylic acid-based water-soluble polymer, polyacrylamide, polyaniline sulfonic acid, and nylon.

[0032] As the hydrophilic polymer, it is more preferable that the hydrophilic polymer has polar groups, wherein the polar groups are groups that form hydrogen bonds with the modification or terminus T of the layer. As the polymer, it is more preferable to use one or more polymers selected from the group consisting of water-soluble polyurethane, polyvinyl alcohol, sodium alginate, acrylic acid-based water-soluble polymer, polyacrylamide, polyaniline sulfonic acid, and nylon.

[0033] Among these, one or more polymers selected from the group consisting of water-soluble polyurethane, polyvinyl alcohol, and sodium alginate are more preferred. As the polymer, a polymer having a urethane bond that possesses both hydrogen bond donor and hydrogen bond acceptor properties is preferred, and from this viewpoint, the water-soluble polyurethane is particularly preferred.

[0034] (Embodiment 2: Method for producing a two-dimensional particle-containing composition) The following describes in detail the method for producing a two-dimensional particle-containing composition according to embodiments of the present invention, but this disclosure is not limited to such embodiments.

[0035] The method for producing the two-dimensional particle-containing composition of this embodiment is: (a) The following equation: M m AX n (In the formula, M is It is at least one metallic element M1 from groups 3, 4, 5, 6, or 7 whose ionization energy is higher than that of Ti. This is a combination of a metallic element M1 that accounts for 50 atomic percent or more of M, and a metallic element M2 from groups 3, 4, 5, 6, or 7 other than metallic element M1 that accounts for 50 atomic percent or less of M. 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) Performing an etching treatment to remove at least some A atoms from the precursor using an etching solution containing a metal compound containing a metal cation and a fluoride, and an intercalation treatment of the metal cation, (c) Wash the processed product obtained by the etching process and the intercalation process with water to obtain a water-washed product. (d) Mixing the water-washed material with a dispersion medium having a dielectric constant greater than that of water, intercalating the dispersion medium, and obtaining an intercalated material, (e) Using the intercalation-treated material, perform delamination in the presence of a dispersion medium with a relative permittivity greater than that of water. This includes the following. In the manufacturing method of this embodiment, the composition of MXene is such that, as described above, more than half of the metal elements have an ionization energy higher than Ti, etching is performed, for example, with a fluoride-containing etching solution, and further, in the manufacturing process, metal cation intercalation and mixing with a high dielectric constant dispersion medium are performed, thereby, a two-dimensional particle-containing composition with sufficient monolayer formation and sufficient stability due to the presence of fluorine and oxygen elements can be obtained as a result, which has excellent oxidation resistance.

[0036] The following details each step of the above manufacturing method. ·Process (a) First, a predetermined precursor is prepared. In this embodiment, the 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 It is at least one metallic element M1 from groups 3, 4, 5, 6, or 7 whose ionization energy is higher than that of Ti. This is a combination of a metallic element M1 that accounts for 50 atomic percent or more of M, and a metallic element M2 from groups 3, 4, 5, 6, or 7 other than metallic element M1 that accounts for 50 atomic percent or less of M. 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.

[0037] The above M, X, n, and m are as described in MXene. 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.

[0038] The MAX phase is M m X n The MAX phase has a crystal structure in which a layer composed of A atoms is located between two layers represented by (each X may have a crystal lattice located within an octahedral array of M). Typically, in the case of 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 nIt 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").

[0039] The MAX phase described above can be manufactured by known methods. For example, VC powder, V 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.

[0040] ·Process (b) Using an etching solution containing a metal compound containing metal cations and a fluoride, A atoms (and possibly some M atoms) are etched (removed and possibly separated into layers) from the precursor, and intercalation of the metal cations is performed.

[0041] The etching solution contains a fluoride as described above. For example, HF (hydrofluoric acid) can be used as a fluoride. Preferably, the etching solution contains HF and one or more of H3PO4, HCl, HI, and H2SO4. For example, etching can be performed by the so-called MILD method, in which HF is generated by reacting HCl and LiF contained in the etching solution in situ. However, it is preferable to etch with an etching solution containing HF (hydrofluoric acid) as described above, the so-called ACID method, or to etch with an etching solution further containing phosphoric acid. These methods are preferable because they make it easier to obtain flake-shaped layered material particles (MXene particles) with a large planar region and a number-average ferret diameter of preferably 3 μm or more than the MILD method.

[0042] The etching solution contains a metal compound containing a metal cation, as described above. The reason why the etching solution according to this embodiment contains a metal compound containing a metal cation is as follows: In the case where the main component of the metal element M constituting the MAX phase is Ti, by etching and then intercalation treatment, M m X nIt was possible to create a single layer. However, preliminary experiments conducted by the inventors revealed that when the main component of the metal element M constituting the MAX phase was not Ti, but a metal element with a higher ionization energy than Ti, it was difficult to achieve intercalation of metal cations using the etching followed by intercalation treatment method. Therefore, the inventors investigated and found that along with etching (removal and possibly layer separation) of A atoms (and possibly some M atoms) from the MAX phase, M m X n We discovered that by performing a metal cation intercalation treatment, which involves inserting monovalent metal cations between layers, metal cation intercalation can be achieved even if the main metal element M constituting the MAX phase has a higher ionization energy than Ti.

[0043] Examples of metal cations include one or more selected from the group consisting of Li ions, Na ions, and K ions. A metal compound containing a metal cation includes at least one of the Li compound, Na compound, and K compound. Examples of metal compounds containing a metal cation include ionic compounds in which the above metal cation and a cation are bonded, such as chlorides of the above metal cation. A preferred metal compound containing a metal cation is lithium chloride.

[0044] The content of the metal compound containing metal cations in the etching solution is preferably 0.001% by mass or more. More preferably, the above content is 0.01% by mass or more, and even more preferably 0.1% by mass or more. On the other hand, from the viewpoint of dispersibility in the solution, it is preferable that the content of the metal compound containing metal cations in the etching solution is 10% by mass or less.

[0045] Other etching conditions are not particularly limited and known conditions can be used. The etching solution may include, for example, pure water as a solvent. When HF is used as the fluoride in the etching solution, the HF concentration may be 1.5 M or more and 14 M or less. When one or more of H3PO4, HCl, HI, and H2SO4 are included along with the fluoride (e.g., HF), the H3PO4 concentration may be 5.5 M or more, the HCl concentration 6.0 M or more, the HI concentration 5.0 M or more, and the H2SO4 concentration 5.0 M or more. In etching of the A atoms, some of the M atoms may be selectively etched along with the A atoms. An example of an etched product obtained by the etching is a slurry.

[0046] ·Process (c) The processed material obtained by the etching process and the intercalation process is washed with water to obtain a water-washed material. The amount of water mixed with the etched material and the washing method are not particularly limited. For example, water may be added and stirred, or centrifuged. Stirring methods include handshakes, automatic shakers, shear mixers, pot mills, 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. The washing with water may be performed once or more. Preferably, washing with water is performed multiple times. Specifically, steps (i) to (iv) of the process of (i) adding water (to the etched material or the remaining precipitate obtained in (iv) below), (ii) stirring, (iii) centrifuging the stirred material, and (iv) discarding the supernatant after centrifugation and recovering the remaining precipitate may be performed two or more times, for example, within a range of 15 times or less.

[0047] ·Process (d) The aforementioned water-washed material is mixed with a dispersion medium whose relative permittivity is greater than that of water, and the dispersion medium is intercalated to obtain an intercalated product. The ratio of the water-washed material to the dispersion medium can be 0.1 g to 10 g of water-treated material in terms of solid content per 1 mL to 100 mL of dispersion medium (in production scale, the solid content of both the dispersion medium and the water-treated material can be increased in this ratio). In this process, the stirring mixture containing the water-washed material and the dispersion medium can be stirred at 20 to 25°C (room temperature). Examples of 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, for example, between 10 and 24 hours.

[0048] ·Process (e) Using the intercalation-treated material, delamination is performed in the presence of a dispersion medium with a relative permittivity greater than that of water. The above delamination process makes it possible to create single-layer or thin-layer MXene. For example, stirring methods include handshakes and automatic shakers. 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 processed. In the manufacturing method of this embodiment, ultrasonic treatment is not performed as delamination. As mentioned above, since ultrasonic treatment is not performed, particle breakage is less likely to occur, and as a result, single-layer or thin-layer MXene can be obtained as layered material particles with a large plane parallel to the particle layer, i.e., a large two-dimensional plane, and a large number-mean ferret diameter.

[0049] The dispersion medium used for mixing, which has a relative permittivity greater than that of water, is the same as the dispersion medium with a relative permittivity greater than that of water described above (Embodiment 1: Two-dimensional particle-containing composition).

[0050] The delamination can be carried out, for example, by the following method: the slurry after mixing with a dispersion medium having a dielectric constant greater than that of water is centrifuged and the supernatant is collected; then, a dispersion medium having a dielectric constant greater than that of water is added to the supernatant; then, after stirring by, for example, a handshake or an automatic shaker, the mixture is centrifuged and the supernatant is collected, and this process is repeated. Then, the collected supernatant is centrifuged and the resulting supernatant is discarded to obtain a clay-like single-layer or thin-layer MXene as the delamination product.

[0051] (Embodiment 3: A film formed from a two-dimensional particle-containing composition) This embodiment includes a film obtained using the two-dimensional particle-containing composition. The film formed with the two-dimensional particle-containing composition exhibits excellent oxidation resistance.

[0052] The method for forming the film according to this embodiment is not limited and includes filtration, coating, immersion, etc. As a filtration method, for example, a two-dimensional particle-containing composition can be filtered by suction. For the filter used in suction filtration, for example, a membrane filter (Merck KGaA, Durapore, pore size 0.45 μm) can be used. As coating methods, for example, spray coating using a nozzle such as a one-fluid nozzle, two-fluid nozzle, or airbrush, slit coating using a table coater, comma coater, or bar coater, screen printing, metal mask printing, spin coating, immersion, brushing, and dropping can be used.

[0053] The above coating and drying process may be repeated multiple times as needed until a film of the desired thickness is obtained. Drying and curing can be carried out, for example, using an atmospheric pressure oven or a vacuum oven at a temperature of 80°C to 400°C.

[0054] The resulting film can be used, for example, as a conductive film. For instance, it can be used in applications requiring high conductivity, such as electrodes or electromagnetic shielding (EMI shielding) in any suitable electrical device. The electrodes are not particularly limited, but could include, for example, capacitor electrodes, battery electrodes, biosignal sensing electrodes, sensor electrodes, or antenna electrodes. By using the film of this embodiment, large-capacity capacitors and batteries, low-impedance biosignal sensing electrodes, and highly sensitive sensors and antennas can be obtained in smaller volumes (device occupancy volumes). [Examples]

[0055] The present invention will be described in more detail below with reference to examples. The present invention is not limited by the following examples, and can be implemented with appropriate modifications within the scope that is consistent with the spirit described above and below, and all such modifications are included within the technical scope of the present invention.

[0056] [Fabrication of single-layer MXene] [Example 1 of the present invention] In Example 1 of the present invention, a two-dimensional particle-containing composition (MXene-containing composition) was prepared by sequentially carrying out the following steps, as detailed below: (1) preparation of a precursor (MAX), (2) etching of the precursor and Li intercalation, (3) washing with water, (4) intercalation with a high dielectric constant dispersion medium (N-methylformamide), and (5) delamination.

[0057] (1) Preparation of the precursor (MAX) VC powder, V 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 3:1:1 and mixed for 24 hours. The resulting mixed powder was calcined at 1600°C for 2 hours under an Ar atmosphere. The resulting calcined body (block-shaped MAX) was then pulverized with an end mill to a maximum size of 40 μm or less. This yielded V4AlC3 particles as a precursor (powdered MAX).

[0058] (2) Etching of the precursor and Li intercalation Using the V4AlC3 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 V4AlC3 powder. (Etching conditions) • Precursor: V4AlC3 (passed through a 45μm sieve) • Etching solution composition: 49% HF 60 mL • Metal salt: LiCl 3g • Amount of precursor added: 3.0g • Reaction vessel: 100mL iBoy Etching temperature: 50℃ Etching time: 48 hours • Stirrer rotation speed: 400 rpm

[0059] (3) Water washing The slurry was divided equally into two portions and placed into two 50 mL centrifuge tubes. The mixture was then centrifuged at 3500 G for 5 minutes, and the supernatant was discarded. Next, (i) 35 mL of pure water was added to the remaining precipitate in each centrifuge tube, (ii) the mixture was stirred by handshake, (iii) the mixture was centrifuged at 3500 G for 5 minutes, and (iv) the supernatant was removed. Steps (i) through (iv) were repeated a total of 11 times. Finally, the mixture was centrifuged at 3500 G for 5 minutes, the supernatant was discarded, and the mixture was converted to V4C3T. s - A water-based clay was obtained.

[0060] (4) Intercalation of the dispersion medium by mixing with a high dielectric constant dispersion medium (N-methylformamide) V4C3T prepared by the above method s - A water-based clay medium and N-methylformamide (NMF) as a high dielectric constant dispersion medium were mixed under the following conditions, and NMF intercalation was performed. (Mixing conditions with high dielectric constant dispersion medium (N-methylformamide)) V4C3T s - Moisture-based clay (MXene after washing): Solid content 0.5g ·Dispersion medium: NMF 20mL • Reaction vessel: 100mL iBoy ·Temperature: 20~25℃ (room temperature) • Stirring time: 11 hours • Stirring speed: 700 rpm

[0061] (5) Delamination The slurry obtained by mixing with the above NMF was transferred to a 50 mL centrifuge tube, 20 mL of NMF was added, and the mixture was centrifuged at 3500 G for 5 minutes using a centrifuge, after which the supernatant was collected. Then, (i) 35 mL of NMF was added to the supernatant, (ii) the mixture was stirred in a shaker for 15 minutes, (iii) the mixture was centrifuged at 3500 G for 5 minutes, and (iv) the supernatant containing the monolayered MXene was collected. Steps (i) to (iv) were repeated a total of four times to collect all the supernatant. Then, the obtained supernatant was centrifuged at 4300 G for 2 hours using a centrifuge to precipitate the MXene, and the supernatant was discarded. The precipitate was then obtained as a two-dimensional particle-containing composition.

[0062] [Examples 2 and 3 of the present invention] In Example 2 of the present invention, a two-dimensional particle-containing composition was obtained in the same manner as in Example 1 of the present invention, except that in the preparation of the precursor (MAX) described above, Nb powder, Al powder, and C powder (all manufactured by Kojun Chemical Laboratory Co., Ltd.) were mixed in a molar ratio of 2:1:1, and in Example 3 of the present invention, Mo powder, Ti powder, Al powder, and C powder (all manufactured by Kojun Chemical Laboratory Co., Ltd.) were mixed in a molar ratio of 2:2:1:3 in the preparation of the precursor (MAX) described above.

[0063] [Comparative Examples 1 and 2] In Comparative Example 1, the composition was obtained in the same manner as in Example 1 of the present invention, except that in the preparation of the precursor (MAX) described above (1), Ti powder, Al powder, and C powder (all manufactured by Kojun Chemical Laboratory Co., Ltd.) were mixed in a molar ratio of 2:1:1; in Comparative Example 2, the composition was obtained in the preparation of the precursor (MAX) described above (1), TiC powder, Ti powder, and Al powder (all manufactured by Kojun Chemical Laboratory Co., Ltd.) were mixed in a molar ratio of 2:1:1; and in Comparative Examples 1 and 2, the intercalation of the high dielectric constant dispersion medium (N-methylformamide) described above (4) was not performed, and the delamination described above (5) was performed with pure water instead of NMF.

[0064] [Comparative Examples 3-5] In Comparative Examples 3 to 5, compositions were obtained in the same manner as in Examples 1 to 3 of the present invention, except that both (4) intercalation of the high dielectric constant dispersion medium (N-methylformamide) and (5) delamination were carried out using TMAOH instead of NMF.

[0065] [Comparative Example 6] In Comparative Example 6, the composition was obtained in the same manner as in Comparative Example 3, except that both (4) intercalation of the high dielectric constant dispersion medium (N-methylformamide) and (5) delamination were not performed.

[0066] The above comparative examples 1 to 6 correspond to the examples shown in Non-Patent Document 1.

[0067] 〔evaluation〕 The compositions obtained in Examples 1-3 and Comparative Examples 1-6 were used to evaluate their dispersibility and oxidation resistance. Details of each evaluation method are shown below. In Examples 1-3, etching was performed using an aqueous HF solution, so it is presumed that the MXene particles have oxygen atoms and fluorine atoms as surface groups.

[0068] Furthermore, in this embodiment, since LiCl is used as a metal compound containing a metal cation in the manufacturing process of the two-dimensional particle-containing composition, the obtained two-dimensional particle-containing composition is considered to contain Li ions.

[0069] 1.Dispersibility 40 mL of MXene 0.01% by mass solution was centrifuged using a centrifuge at 3500 G for 1 minute. After removing the supernatant, the weight of the precipitate was measured and evaluated as follows. (Criteria for evaluating variance) Precipitate is 30% by mass or less of the total volume of the above solution: A Precipitate is more than 30% by mass and less than 80% by mass of the total volume of the above solution: B Precipitate makes up 80% or more of the total volume of the above solution: C

[0070] 2.Oxidation resistance Oxidation resistance was evaluated by preparing a dispersion solution of MXene, conducting accelerated testing, and then measuring the absorbance at a predetermined wavelength, as detailed below.

[0071] (solution preparation) MXene is diluted with ultrapure water, and the concentration of MXene is 1 × 10⁻⁶. -4 A dispersion solution of mg / mL was prepared. Then, • MXene with M being V-type (V being 50 atomic percent or more) exhibits a plasmon resonance peak at a wavelength of 900 nm. • MXene, in which M is Nb-based (Nb content of 50 atomic percent or more), exhibits a plasmon resonance peak at a wavelength of 880 nm. • MXene with M being Mo-based (Mo is 50 atomic percent or more) exhibits a plasmon resonance peak at a wavelength of 500 nm. • Other wavelengths where MXene has a plasmon resonance peak: 780nm The solution was prepared so that the absorbance readings on the calibration curve at each wavelength were in the range of 0.4 to 0.5. To ensure dispersibility after preparation, it was treated in a 28 kHz ultrasonic bath for 10 seconds.

[0072] (Accelerated testing) The accelerated test was performed in a heated water bath with stirring. Specifically, 40 mL of the MXene dispersion solution was heated in a water bath at a set temperature of 60°C (actual temperature 50°C) with a stirring speed of 500 rpm for 7 days.

[0073] (Absorbance measurement) The absorbance of the dispersion solution before the accelerated test and the absorbance of the dispersion solution after heating for 7 days were measured. An ASV-11D-H (manufactured by AS ONE) was used as the measuring instrument. The measurement wavelengths were as follows: 900 nm for MXenes where M is V-based (V is 50 atomic% or more), 880 nm for MXenes where M is Nb-based (Nb is 50 atomic% or more), 500 nm for MXenes where M is Mo-based (Mo is 50 atomic% or more), and 780 nm for all other MXenes. The absorbance of the dispersion solution before the accelerated test was set to 100%, and the ratio (%) of the obtained absorbance to this absorbance of the dispersion solution before the accelerated test was calculated. A higher ratio (%) indicates a smaller degree of oxidation and superior oxidation resistance.

[0074] In this example, the ratio (%) of the obtained absorbance to the absorbance of the dispersion solution before the accelerated test was used for evaluation according to the following evaluation criteria. Specifically, if the ratio to the absorbance of the dispersion solution before the accelerated test was higher than 70%, it was considered to have excellent oxidation resistance (evaluation: A). The ratio to the absorbance of the dispersion solution before the accelerated test was preferably 73% or higher, and more preferably 77% or higher. For example, in Example 1 of the Invention, the ratio to the absorbance of the dispersion solution before the accelerated test was 77%, in Example 2 it was 80%, and in Example 3 it was 73%. (Evaluation criteria for oxidation resistance) The ratio of the absorbance of the dispersion solution before the accelerated test is higher than 70%: A If the ratio of the absorbance of the dispersion solution before the accelerated test is higher than 50% and 70% or less: B The ratio of the absorbance of the dispersion solution before the accelerated test to 50% or less: C

[0075] Table 1 shows the evaluation results for dispersibility and oxidation resistance.

[0076] [Table 1]

[0077] Table 1 shows the following: In Comparative Examples 1 and 2, the MXene composition was outside the specifications of this embodiment, and the resulting two-dimensional particle-containing compositions exhibited poor oxidation resistance. In Comparative Examples 3 to 5, although the MXene composition was within the specifications, the dispersion medium included was TMAOH, and all of them exhibited considerably poor oxidation resistance. In Comparative Example 6, since intercalation and delamination of Li and other elements were not performed, and it was a multilayer MXene, its dispersibility was considerably low, and its oxidation resistance could not be evaluated. In contrast, the two-dimensional particle-containing compositions of Examples 1 to 3 of the present invention had an MXene composition within the specifications and contained a dispersion medium with a relative permittivity greater than that of water, thus exhibiting high dispersibility and excellent oxidation resistance.

[0078] The disclosures in this specification may include the following aspects: <1> The mixture comprises two-dimensional particles of a layered material containing one or more layers, and a dispersion medium with a relative permittivity greater than that of water. The one or more layers described above are defined by the following formula: M m X n (In the formula, M is It is at least one metallic element M1 from groups 3, 4, 5, 6, or 7 whose ionization energy is higher than that of Ti. This is a combination of a metallic element M1 that accounts for 50 atomic percent or more of M, and a metallic element M2 from groups 3, 4, 5, 6, or 7 other than metallic element M1 that accounts for 50 atomic percent or less of M. 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 (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) present on the surface of the layer body, The two-dimensional particle composition comprises two-dimensional particles having fluorine and oxygen elements. <2> The aforementioned M is one or more metallic elements selected from the group consisting of V, Nb, and Mo. <1> A two-dimensional particle-containing composition as described above. <3> It contains one or more selected from the group consisting of Li ions, Na ions, and K ions. <1> or <2> A two-dimensional particle-containing composition as described above. <4> The dispersion medium having a relative permittivity greater than that of water comprises at least one of N-methylformamide and N-methylacetamide. <1> ~ <3> A two-dimensional particle-containing composition as described in any one of the following. <5> The layer body of the aforementioned two-dimensional particles consists of one or more particles selected from the group consisting of V2C, V4C3, and Mo2Ti2C3. <1> ~ <4> A two-dimensional particle-containing composition as described in any one of the following. <6> Further containing polymers, <1> ~ <5> A two-dimensional particle-containing composition as described in any one of the following. <7> <1> ~ <6> A film formed from a two-dimensional particle-containing composition as described in any one of the following. <8> (a) The following equation: M m AX n (In the formula, M is It is at least one metallic element M1 from groups 3, 4, 5, 6, or 7 whose ionization energy is higher than that of Ti. This is a combination of a metallic element M1 that accounts for 50 atomic percent or more of M, and a metallic element M2 from groups 3, 4, 5, 6, or 7 other than metallic element M1 that accounts for 50 atomic percent or less of M. 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) Performing an etching treatment to remove at least some A atoms from the precursor using an etching solution containing a metal compound containing a metal cation and a fluoride, and an intercalation treatment of the metal cation, (c) Wash the processed product obtained by the etching process and the intercalation process with water to obtain a water-washed product. (d) Mixing the water-washed material with a dispersion medium having a dielectric constant greater than that of water, intercalating the dispersion medium, and obtaining an intercalated material, (e) Using the intercalation-treated material, perform delamination in the presence of a dispersion medium with a relative permittivity greater than that of water. A method for producing a two-dimensional particle-containing composition. <9> The metal compound containing the metal cation comprises at least one of Li compounds, Na compounds, and K compounds. <8> A method for producing the two-dimensional particle-containing composition described above. <10> The aforementioned M is one or more metallic elements selected from the group consisting of V, Nb, and Mo. <8> or <9> A method for producing the two-dimensional particle-containing composition described above. <11> The dispersion medium having a relative permittivity greater than that of water comprises at least one of N-methylformamide and N-methylacetamide. <8> ~ <10> A method for producing a two-dimensional particle-containing composition as described in any one of the following. [Industrial applicability]

[0079] The two-dimensional particle-containing composition of this disclosure exhibits excellent dispersibility and oxidation resistance. Films formed using this two-dimensional particle-containing composition can be used in any suitable application and are preferably used as electrodes such as electromagnetic shields (EMI shields), capacitor electrodes, battery electrodes, biosignal sensing electrodes, sensor electrodes, and antenna electrodes. [Explanation of Symbols]

[0080] 1a, 1b layer body (M m X n layer) 3a, 5a, 3b, 5b Modifier or Terminus T 7a, 7b MXene layer 10, 10a, 10b Layered material particles

Claims

1. The mixture comprises two-dimensional particles of a layered material containing one or more layers, and a dispersion medium with a relative permittivity greater than that of water. The one or more layers are defined by the following formula: M ｍ X ｎ (In the formula, M is M is a metallic element from groups 3, 4, 5, 6, or 7 whose ionization energy is higher than that of Ti. １ Is it, Metal elements M that make up 50 atomic percent or more of M １ And, metal elements M that make up 50 atomic percent or less of M １ Metal elements M from groups 3, 4, 5, 6, and 7 other than the others ２ This is a combination of the above, 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 oxygen atom, and a hydrogen atom), The aforementioned two-dimensional particles are a two-dimensional particle-containing composition having fluorine and oxygen elements.

2. The two-dimensional particle-containing composition according to claim 1, wherein M is one or more metallic elements selected from the group consisting of V, Nb, and Mo.

3. A two-dimensional particle-containing composition according to claim 1, comprising one or more selected from the group consisting of Li ions, Na ions, and K ions.

4. The two-dimensional particle-containing composition according to claim 1, wherein the dispersion medium having a relative permittivity greater than that of water comprises at least one of N-methylformamide and N-methylacetamide.

5. The layer body of the two-dimensional particles is V ２ C, V ４ C ３ , and Mo ２ Ti ２ C ３ The two-dimensional particle-containing composition according to claim 1, which is one or more selected from the group consisting of

6. The two-dimensional particle-containing composition according to claim 1, further comprising a polymer.

7. A film formed from a two-dimensional particle-containing composition according to any one of claims 1 to 6.

8. (a) The following formula: M ｍ AX ｎ (In the formula, M is M is a metallic element from groups 3, 4, 5, 6, or 7 whose ionization energy is higher than that of Ti. １ Is it, Metal elements M that make up 50 atomic percent or more of M １ And, metal elements M that make up 50 atomic percent or less of M １ Metal elements M from groups 3, 4, 5, 6, and 7 other than the others ２ This is a combination of the above, 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) Performing an etching treatment to remove at least some A atoms from the precursor using an etching solution containing a metal compound containing a metal cation and a fluoride, and an intercalation treatment of the metal cation, (c) Wash the treated product obtained by the etching process and the intercalation process with water to obtain a water-washed product. (d) Mixing the water-washed material with a dispersion medium having a relative permittivity greater than that of water, intercalating the dispersion medium, and obtaining an intercalated material, (e) Using the intercalation-treated material, delamination is performed in the presence of a dispersion medium with a relative permittivity greater than that of water. A method for producing a two-dimensional particle-containing composition.

9. The method for producing a two-dimensional particle-containing composition according to claim 8, wherein the metal compound containing the metal cation comprises at least one of Li compounds, Na compounds, and K compounds.

10. A method for producing a two-dimensional particle-containing composition according to claim 8 or 9, wherein M is one or more metal elements selected from the group consisting of V, Nb, and Mo.

11. A method for producing a two-dimensional particle-containing composition according to claim 8 or 9, wherein the dispersion medium having a relative permittivity greater than that of water comprises at least one of N-methylformamide and N-methylacetamide.

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