Conductive film, particulate substance, paste, and method for manufacturing conductive film

Abstract

Provided is a conductive film containing MXene and achieving higher conductivity. A conductive film containing particles of a layered material having one or more layers, wherein the layers include: a layer main body represented by the following formula: M m X n (wherein M is at least one metal of Groups 3, 4, 5, 6, and 7, X is a carbon atom, a nitrogen atom, or a combination thereof, n is 1 or more and 4 or less, and m is greater than n and 5 or less); a modification or a terminal 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; and a peak-related χ-axis direction rocking curve full width at half maximum of a (00I) plane (I is a natural number multiple of 2) obtained by X-ray diffraction measurement of the conductive film is 10.3° or less.

Description

Technical Field

[0001] The present invention relates to a conductive film, a particulate material, a slurry, and a method for producing a conductive film using the slurry. Background Art

[0002] In recent years, MXene has attracted attention as a new conductive material. MXene is a so-called two-dimensional material, and as described later, it is a layered material with one or more layers. Generally, MXene takes the form of particles (including powders, flakes, nanosheets, etc.) of these layered materials.

[0003] It is known that MXene particles can be deposited in the form of slurry by suction filtration or sprayed onto a substrate to form a film. There are reports that thin films (conductive films) containing MXene particles show electromagnetic shielding effects. More specifically, in Ti3C2T, one of the MXenes, x The (filler-free) film had an electrical conductivity of 4665 S / cm. It is believed that such an electrical conductivity can provide an excellent electromagnetic shielding effect (see Fig. 3B of Non-Patent Document 1).

[0004] Prior art literature

[0005] Non-patent literature

[0006] Non-Patent Literature 1: Faisal Shahzad, et al., "Electromagnetic interference shielding with 2D transition metal carbides (MXenes)", Science, 09 Sep 2016, Vol. 353, Issue 6304, pp. 1137-1140 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, the maximum electrical conductivity reported in Non-Patent Document 1 is only 4665 S / cm. In order to obtain a sufficient effect as an electromagnetic shield, a higher electrical conductivity must be achieved.

[0009] An object of the present invention is to provide a conductive film comprising MXene and capable of achieving higher electrical conductivity. Another object of the present invention is to provide a particulate material capable of providing such a conductive film, a slurry containing the particulate material, and a method for producing a conductive film using the slurry.

[0010] Means of solving the problem

[0011] According to a first aspect of the present invention, there is provided a conductive film comprising particles of a layered material having one or more layers, wherein the layer comprises:

[0012] By the following formula: M m X n A layer body represented by (wherein, M is at least one metal of Groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof, n is 1 to 4, and m is greater than n and 5 or less);

[0013] a modification or terminal T present on the surface of the main body of the layer (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),

[0014] The full width at half maximum of the x-axis direction rocking curve associated with the peak of the (00I) plane (I is a natural number multiple of 2) obtained by X-ray diffraction measurement of the conductive film is 10.3° or less.

[0015] In one embodiment of the first aspect of the present invention, the full width at half maximum of the rocking curve in the x-axis direction may be 8.8° or less.

[0016] In one embodiment of the first aspect of the present invention, the conductive film may have an electrical conductivity of 12000 S / cm or higher.

[0017] In one embodiment of the first aspect of the present invention, the conductive film may have a density of 3.00 g / cm 3 Density above.

[0018] In one embodiment of the first aspect of the present invention, the conductive film may have an arithmetic mean roughness of 120 nm or less.

[0019] In one embodiment of the first aspect of the present invention, the conductive film can be used as an electromagnetic shield.

[0020] According to a second aspect of the present invention, there is provided a particulate material comprising particles of a layered material having one or more layers, wherein the layers comprise:

[0021] By the following formula: M m X n A layer body represented by (wherein, 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 1 to 4, and m is greater than n and 5 or less);

[0022] a modification or terminal T formed on the surface of the main body of the layer (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),

[0023] The ratio of A to M is 0.30 mol% or less,

[0024] The A is at least one element from Groups 12, 13, 14, 15, and 16.

[0025] According to a third aspect of the present invention, there is provided a particulate material comprising particles of a layered material having one or more layers, wherein the layers comprise:

[0026] By the following formula: M m X n A layer body represented by (wherein, M is at least one metal of Groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof, n is 1 to 4, and m is greater than n and 5 or less);

[0027] a modification or terminal T formed on the surface of the main body of the layer (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),

[0028] The proportion of particles having a thickness of more than 20 nm in the particulate material is less than 2%.

[0029] According to a fourth aspect of the present invention, there is provided a particulate material comprising particles of a layered material having one or more layers, wherein the layers comprise:

[0030] By the following formula: M m X n A layer body represented by (wherein, 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 1 to 4, and m is greater than n and 5 or less);

[0031] a modification or terminal T formed on the surface of the main body of the layer (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),

[0032] The maximum thickness of particles contained in the particulate material is 500 nm or less.

[0033] In one embodiment of the fourth aspect of the present invention, the proportion of particles having a thickness exceeding 20 nm in the particulate material may be less than 2%.

[0034] In one embodiment of the third or fourth aspect of the present invention, the ratio of A to M is 0.30 mol% or less,

[0035] The A may be at least one element from Groups 12, 13, 14, 15, and 16.

[0036] In any one of the second to fourth aspects of the present invention, the M may be Ti, and the A may be A1.

[0037] According to a fifth aspect of the present invention, there is provided a slurry comprising the particulate material according to any one of the second to fourth aspects in a liquid medium.

[0038] According to a sixth aspect of the present invention, there is provided a method for manufacturing a conductive film, comprising:

[0039] (a) applying the slurry according to the fifth aspect of the present invention on a substrate to form a precursor of the conductive film containing the layered material particles, and

[0040] (b) drying the precursor.

[0041] In one embodiment of the sixth aspect of the present invention, the application of the slurry in (a) can be performed by spraying, spin coating, or doctor blade method.

[0042] In one embodiment of the sixth aspect of the present invention, the steps (a) and (b) may be repeated a total of two or more times.

[0043] The conductive film according to the first aspect of the present invention can be produced by the method for producing a conductive film according to the sixth aspect of the present invention.

[0044] Effects of the Invention

[0045] According to the present invention, a conductive film is provided, comprising particles of a predetermined layered material (also referred to herein as "MXene"), wherein the full width at half maximum of the rocking curve in the x-axis direction is 10.3° or less. Thus, the provided conductive film contains MXene and is capable of achieving high electrical conductivity. Furthermore, the present invention also provides a particulate material capable of providing such a conductive film, a slurry containing the particulate material, and a method for producing a conductive film using the slurry. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 These are drawings illustrating a conductive film according to one embodiment of the present invention, wherein (a) is a schematic cross-sectional view showing a conductive film on a substrate, and (b) is a schematic perspective view showing a layered material of the conductive film.

[0047] Figure 2 Schematic cross-sectional views of MXene particles as a layered material that can be used in one embodiment of the present invention are shown. (a) shows a single-layer MXene particle, and (b) shows a multi-layer (two-layer, for example) MXene particle.

[0048] Figure 3 This is a schematic diagram for explaining a method for producing a slurry according to one embodiment of the present invention.

[0049] Figure 4 This is a schematic diagram for explaining a method for producing a conductive film according to one embodiment of the present invention.

[0050] Figure 5 This is a graph plotting the equivalent circle diameter (μm) and brightness of particles contained in the MXene slurry of Comparative Example 1.

[0051] Figure 6 This is a graph plotting the equivalent circle diameter (μm) and brightness of particles contained in the MXene slurry of Example 1.

[0052] Figure 7 This is a graph plotting the equivalent circle diameter (μm) and brightness of particles contained in the MXene slurry of Example 2.

[0053] Figure 8 (a) is a diagram showing the distribution ratio of the brightness of particles contained in the MXene slurries of Comparative Example 1 and Examples 1 and 2, and (b) is an enlarged diagram showing a portion of (a).

[0054] Figure 9 A cross-sectional SEM photograph of the conductive film with a substrate (sample) of Comparative Example 2 obtained using the MXene slurry of Comparative Example 1 is shown.

[0055] Figure 10 A cross-sectional SEM photograph of the conductive film with a substrate (sample) of Example 3 obtained using the MXene slurry of Example 1 is shown.

[0056] Figure 11 A cross-sectional SEM photograph of the conductive film with a substrate (sample) of Example 4 obtained from the MXene slurry of Example 2 is shown.

[0057] Figure 12 This is a diagram illustrating a conductive film produced by a conventional production method, and shows a schematic cross-sectional view of the conductive film on a substrate. DETAILED DESCRIPTION

[0058] Hereinafter, a conductive film, a particulate material, a slurry containing the particulate material, and a method for producing a conductive film using the slurry according to one embodiment of the present invention will be described in detail, but the present invention is not limited to this embodiment.

[0059] Reference Figure 1 The conductive film 30 of this embodiment includes particles 10 of a predetermined layered material. The full width at half maximum of the x-axis rocking curve associated with the peak of the (00I) plane (where I is a natural multiple of 2) obtained by X-ray diffraction measurement of the conductive film 30 is 10.3° or less. The conductive film 30 of this embodiment will be described below using this manufacturing method.

[0060] The specified layered material that can be used in this embodiment is MXene, which is specified as follows:

[0061] A layered material comprising one or more layers, wherein the layer comprises the following layered material (which can be understood as a layered compound, also represented as "M m X n T s ", s is an arbitrary number. In the past, x was sometimes used instead of s):

[0062] By the following formula: M m X n (wherein, M is at least one Group 3, 4, 5, 6, or 7 metal, so-called early transition metals, such as Sc, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and Mn; X is a carbon atom, a nitrogen atom, or a combination thereof; n is 1 to 4; and m is greater than n and 5) a layer body (the layer body may have a lattice in which each X is located within an octahedral array of M);

[0063] A modified or terminal 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 (more specifically, on at least one of two opposing surfaces of the layer body). Typically, n can be 1, 2, 3, or 4, but is not limited thereto.

[0064] In the above formula of 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.

[0065] Such MXene can be synthesized by selectively etching (removing and, if necessary, performing layer separation) A atoms (and, if necessary, a portion of M atoms) from the MAX phase.

[0066] The MAX phase is given by the following formula: m AX n = (wherein, M, X, n and m are as described above, A is at least one element of Groups 12, 13, 14, 15 and 16, usually an element of Group A, typically an element of Group IIIA and Group IVA, and more specifically may include at least one selected from the group consisting of Al, Ga, In, Ti, Si, Ge, Sn, Pb, P, As, S and Cd, preferably Al), and a layer consisting of A atoms is located in the region around M m X nThe MAX phase typically has the following repeating unit when m=n+1: one X atomic layer is arranged between each of the n+1 layers of M atomic layers (these layers are collectively referred to as "M"). m X n The A atomic layer ("A atomic layer") is arranged as the next layer of the n+1th M atomic layer, but the present invention is not limited thereto. By selectively etching (removing and layer-separating as needed) the A atoms (and as needed a portion of the M atoms), the A atomic layer (and as needed a portion of the M atoms) is removed from the MAX phase, and the hydroxyl groups, fluorine atoms, chlorine atoms, oxygen atoms, hydrogen atoms, etc. present in the etching solution (usually, an aqueous solution containing fluorine acid is used, but not limited thereto) are removed from the exposed M atoms. m X n The surface of the layer is modified so that the surface is terminated. Etching can be performed using a F-containing － The etching can be carried out using an etching solution such as a mixed solution of lithium fluoride and hydrochloric acid or a method using hydrofluoric acid.

[0067] As described later, to obtain a conductive film with highly oriented MXene particles and a predetermined rocking curve full width at half maximum, etching is preferably performed to reduce the number of A atoms remaining in the MXene particles. Fewer remaining A atoms contribute to further improving the purity of the monolayer MXene in the particulate material and slurry containing it, as described later, and further increasing the in-plane size of the monolayer MXene particles.

[0068] In addition, in order to obtain a conductive film with high orientation of MXene particles and a specified rocking curve half-maximum full width, after etching, it is preferred to implement a process that causes MXene layer separation (stratification, so that multi-layer MXene becomes MXene with fewer layers, preferably separated into single-layer MXene). In order to obtain MXene particles with a two-dimensional shape with a larger aspect ratio (single-layer·few-layer MXene particles, preferably single-layer MXene particles), such a layer separation process is more preferably a method that causes less damage to the MXene particles. The layer separation process can be implemented by any appropriate method, such as ultrasonic treatment, manual shaking or automatic shaking, but ultrasonic treatment will destroy the MXene particles (fragmentation) due to excessive shear force, so it is preferred to apply appropriate shear force by manual shaking or automatic shaking. If there are fewer A atoms remaining in the MXene particles, the influence caused by the binding force of the A atoms is smaller, so the MXene particles can be effectively layered with a smaller shear force.

[0069] MXene is known to be represented by the above formula: m X n Express it like the following.

[0070] 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.)

[0071] 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,

[0072] Ti4N3, V4C3, Nb4C3, Ta4C3, (Ti, Nb)4C3, (Nb, Zr)4C3, (Ti2Nb2)C3, (Ti2Ta2)C3, (V2Ti2)C3, (V2Nb2)C3, (V2Ta2)C3, (Nb2Ta2)C3, (Cr2Ti2)C3, (Cr 2V2)C3, (Cr2Nb2)C3, (Cr2Ta2)C3, (Mo2Ti2)C3, (Mo2Zr2)C3, (Mo2Hf2)C3, (Mo2V2)C3, (Mo2Nb2)C3, (Mo2Ta2)C3, (W2Ti2)C3, (W2Zr2)C3, (W2Hf2)C3

[0073] Typically, in the above formula, M can be titanium or vanadium, and X can be a carbon atom or a nitrogen atom. For example, MAX phase is Ti3A1C2, and MXene is Ti3C2T s (In other words, M is Ti, X is C, n is 2, and m is 3).

[0074] The MXene particles 10 synthesized in this way, such as Figure 2As schematically shown in FIG, particles of layered materials may be particles (as an example of MXene particles 10, in FIG. Figure 2 (a) shows a single layer of MXene particles 10a. Figure 2 (b) shows two layers of MXene particles 10b, but is not limited to these examples). More specifically, the MXene layers 7a and 7b have: m X n The layer body represented by m X n Layers) 1a, 1b; modified or terminal T 3a, 5a, 3b, 5b present on the surface of the layer bodies 1a, 1b (more specifically, at least one of the two surfaces facing each other of each layer). Therefore, MXene layers 7a, 7b are also represented as "MXene". m X n T s ", s is an arbitrary number. The MXene particle 10 may be a particle in which the MXene layers are separated and exist as one layer ( Figure 2 The single-layer structure shown in (a), so-called single-layer MXene particles 10a), can also be a laminated particle ( Figure 2 The multilayer structure shown in (b), the so-called multilayer MXene particles 10b), can also be a mixture thereof. The MXene particles 10 can be particles (also referred to as powder or flakes) as an aggregate composed of single-layer MXene particles 10a and / or multi-layer MXene particles 10b. In the case of multi-layer MXene particles, the two adjacent MXene layers (for example, 7a and 7b) are not necessarily completely separated, but can be partially in contact. In this embodiment, as described later, in the MXene particles 10, it is preferred that the single-layer MXene particles are as much as possible than the multi-layer MXene particles (the content ratio of the single-layer MXene particles is high).

[0075] Although not limiting to this embodiment, the thickness of each MXene layer (equivalent to the above-mentioned MXene layers 7a and 7b) is, for example, 0.8 nm to 5 nm, and in particular, 0.8 nm to 3 nm (mainly depending on the number of M atomic layers contained in each layer). When the MXene particles are particles of a laminate (multilayer MXene), the interlayer distance (or gap size) of each laminate is Figure 2 The thickness (represented by Δd in (b)) is, for example, 0.8 nm to 10 nm, particularly 0.8 nm to 5 nm, and more particularly about 1 nm.

[0076] The thickness in the direction perpendicular to the layer of the MXene particle (which may correspond to the "thickness" of the MXene particle as a two-dimensional particle) is, for example, greater than 0.8 nm, for example, less than 20 nm, particularly less than 15 nm, and more particularly less than 10 nm. The total number of layers of the MXene particle may be 1 or greater than 2, for example, greater than 1 and less than 10, and particularly greater than 1 and less than 6. When the MXene particle is a particle of a laminate (multilayer MXene), it is preferably a particle of a MXene with a small number of layers. The term "small number of layers" means, for example, that the number of stacking layers of MXene is less than 6. In addition, the thickness in the stacking direction of the particle of the multilayer MXene with a small number of layers is preferably less than 15 nm, particularly preferably less than 10 nm. In this specification, this "multilayer MXene with a small number of layers" is also referred to as "few-layer MXene". In this embodiment, the MXene particles are preferably mostly particles of single-layer MXene and / or few-layer MXene, and more preferably mostly single-layer MXene particles. In other words, the average value of the thickness of the MXene particles is preferably less than 10 nm. The average thickness is more preferably 7 nm or less, and even more preferably 5 nm or less. On the other hand, considering the thickness of a single MXene layer, the lower limit of the thickness of the MXene particles can be 0.8 nm. Therefore, the average thickness of the MXene particles is approximately 1 nm or more.

[0077] The size within the plane (two-dimensional developed surface) parallel to the layer of MXene particles (which can correspond to the "in-plane size" of the MXene particles as two-dimensional particles) is, for example, greater than 0.1 μm, in particular greater than 1 μm, for example, less than 200 μm, in particular less than 40 μm.

[0078] In addition, the above-mentioned dimensions can be obtained as the digital average size (for example, at least 40 digital averages) based on photographs taken with a scanning electron microscope (SEM), a transmission electron microscope (TEM) or an atomic force microscope (AFM), or as the distance in real space calculated from the position in the reciprocal lattice space of the (002) plane measured by the X-ray diffraction (XRD) method.

[0079] The present inventors investigated factors that affect the electrical conductivity in order to achieve higher electrical conductivity than conventional methods (Non-Patent Document 1) in the conductive film 30 containing MXene particles.

[0080] When a conductive film containing MXene particles is prepared by the existing method, Figure 12As schematically shown in FIG, MXene particles (including multilayer MXene particles and single-layer MXene particles) 10 are relatively disorderly stacked on the substrate surface 31a (in other words, the main surface of the film), and there are impurities 19 other than the MXene particles 10. Therefore, due to the steric hindrance of the multilayer MXene particles and the impurities 19, the stacking of the single-layer MXene particles is hindered, and the orientation of the MXene particles as a whole of the conductive film becomes low. The conductive film containing MXene particles has different physical properties due to the orientation of the MXene particles in the film. Figure 12 As shown schematically, if the orientation of the MXene particles 10 is low, it is believed that the contact between the MXene particles 10 is poor (the conductive path is cut off), and the overall electronic conductivity of the conductive film is poor, thus failing to achieve high conductivity. Conversely, if the MXene particles in the film are highly oriented, it is believed that a conductive film with higher conductivity can be obtained.

[0081] Furthermore, the present inventors' research has revealed that in order to obtain a conductive film with highly oriented MXene particles, the particulate material (which may be included in the slurry in this embodiment) serving as the raw material is important. More specifically, it is believed that it is preferable to use a particulate material that satisfies at least one of the following (1) and (2), particularly (1), and preferably both (1) and (2).

[0082] (1) Impurities other than MXene should be minimized

[0083] (2) The number of single-layer MXene particles should be as large as possible compared to multi-layer MXene particles (the content ratio of single-layer MXene particles is high)

[0084] In conventional methods for producing conductive films, after selectively etching A atoms from the MAX phase, unnecessary components are largely removed by centrifugation and separation of the supernatant (recovery / cleaning of the sediment), thereby preparing a slurry containing MXene particles in a liquid medium (aqueous medium). This is because the mixed solution after etching contains not only MXene particles (single-layer MXene particles and multi-layer MXene particles), but also impurities and unnecessary components such as etching solution. However, the particulate matter contained in the slurry obtained in this way does not necessarily meet the above-mentioned aspects (1) and / or (2).

[0085] Further research results of the present inventors have shown that as indicators of the above (1) and / or (2), the particulate material (which can be included in the slurry in this embodiment) can obtain sufficiently high orientation as long as it meets at least one of the following, thereby obtaining a conductive film with high electrical conductivity.

[0086] The smaller the ratio of A atoms to M atoms, the better. Specifically, it is 0.30 mol% or less.

[0087] The smaller the proportion of particles with a thickness of more than 20 nm in the particulate material, the better. Specifically, it should be less than 2%.

[0088] The particulate material preferably does not contain particles with excessive thickness. Specifically, the maximum thickness of the particles contained in the particulate material is 500 nm or less.

[0089] Based on the findings of the present inventors, the particulate material of the present embodiment includes the above-mentioned MXene particles 10 and satisfies at least one of the following (I) to (III).

[0090] (I) With respect to M (at least one metal from Groups 3, 4, 5, 6, or 7) and A (at least one element from Groups 12, 13, 14, 15, or 16) in the above formula, the ratio of A to M is 0.30 mol% or less

[0091] (II) The proportion of particles having a thickness of more than 20 nm in the particulate material is less than 2%, preferably less than 1% (in other words, the proportion of particles having a thickness of less than 20 nm in the particulate material is 98% or more, preferably 99% or more).

[0092] (III) The maximum thickness of particles contained in the particulate material is 500 nm or less, preferably 250 nm or less, more preferably 100 nm or less, and even more preferably 50 nm or less (in other words, the particulate material does not contain particles thicker than 500 nm, preferably does not contain particles thicker than 250 nm, more preferably does not contain particles thicker than 100 nm, and even more preferably does not contain particles thicker than 50 nm).

[0093] In the above (I), M is typically Ti and A is Al.

[0094] From one point of view, the following considerations can be made. Regarding the above (1), unreacted MAX particles and crystals of by-products derived from the etched A atoms (such as crystals of AlF3) constitute impurities. Regarding the above (2), multilayer MXene particles are prone to residual A atoms between their layers. In contrast, if there are many single-layer MXene particles, the etched A atoms are free in the liquid medium and are easily removed as unnecessary components. Therefore, satisfying the above (I) can indicate that there are few impurities and the content ratio of single-layer MXene particles is high, which can satisfy the above (1) and (2). In addition, the following considerations can be made. If A atoms remain between the layers of MXene particles after etching, the binding force of the A atoms will hinder the layer separation of the MXene particles. If a shear force greater than the binding force of the A atoms is applied to promote layer separation, the MXene particles are fragmented and the in-plane size of the MXene particles becomes smaller. If there are few A atoms, the layer separation of the MXene particles can be effectively promoted with a smaller shear force, so that MXene particles with larger in-plane size (preferably single-layer MXene particles) can be obtained. Therefore, satisfying the above (I) indicates that the in-plane size of MXene particles (especially single-layer MXene particles) is relatively large.

[0095] Regarding (I) above, the contents of M and A in the particulate material (or the slurry described later) can be measured by elemental (atomic) analysis such as inductively coupled plasma atomic emission spectrometry (ICP-AES) or X-ray fluorescence spectrometry (XRF), and the ratio of A to M can be calculated based on these measured values.

[0096] From another point of view, the following considerations can be made. Regarding the above (1), impurities other than MXene (such as the above-mentioned MAX particles) may have a size (thickness and / or particle size) greater than 20nm. Regarding the above (2), the thickness of the multilayer MXene particles is greater than the thickness of the single-layer MXene particles and is higher than 20nm. Therefore, satisfying the above (II) can indicate that there are few impurities and the content ratio of the single-layer MXene particles is high, which can satisfy the above (1) and (2).

[0097] From another point of view, the following considerations can be made. Regarding the above (1), the MAX particles will have a thickness greater than 500nm. Therefore, satisfying the above (III) can indicate that the MAX particles are not included and the above (1) can be satisfied. As a conductive film formed by a particulate material, in a conductive film in which MXene particles with a relatively thin thickness (for example, less than 20nm) occupy most of it (for example, more than 98%), if there are very thick particles with a thickness of more than 500nm, even if there is only one, the orientation of the MXene particles will be extremely significantly reduced. As mentioned in (III), the maximum thickness of the particles contained in the particulate material is less than 500nm, which is extremely important for obtaining a conductive film with high orientation of MXene particles.

[0098] Regarding (II) and (III) above, the proportion of particles having a thickness greater than 20 nm in the particulate material and the maximum thickness of the particles contained in the particulate material can be calculated or determined as follows: a liquid composition (or slurry described later) containing the particulate material in a liquid medium is dropped onto a flat (e.g., having an arithmetic mean roughness Ra of 0.5 nm or less) stage (e.g., a silicon wafer), the liquid medium is dried and removed, and an atomic force microscope (AFM) is used to measure the thickness of all particles within the field of view of the AFM (however, particles where two or more particles are obviously overlapped and particles where the overall shape of the particles cannot be predicted are excluded. For example, even in the case of a stacked structure, particles where the outlines (edges) of each layer are substantially aligned are considered to be one particle. For example, particles where most (more than half) of the particles are within the field of view and a part of the particles extends outside the field of view, but the shape of the particles can be roughly understood based on the part within the field of view, are included in the measurement object), and the thickness is calculated or determined based on the measurement results of at least 40 particles. The AFM field of view may be, for example, 30 μm×30 μm, but is not limited thereto. In multiple fields of view, the thickness of all particles within each field of view (however, in the manner described above) is measured until the thickness of at least 40 particles is measured.

[0099] As described above, by dropping the particulate material in the form of a liquid composition (or slurry described later) onto a flat stage and drying to remove the liquid medium, the MXene particles contained in the particulate material can be arranged so that the plane parallel to the MXene layer (two-dimensional unfolded surface) is parallel to the surface of the stage. Therefore, in the case of MXene particles, the measured value of the particle thickness can be measured in the direction perpendicular to the MXene layer (which can correspond to the "thickness" of the MXene particle). However, it should be noted that since the thickness measurement is performed using an AFM probe, the liquid medium will remain between the MXene particle and the stage surface, and the value of the MXene particle thickness measured in this way may be greater than the actual thickness of the MXene particle.

[0100] According to Lambert-Beer's law regarding light absorption, the thicker the particle, the lower the brightness of light passing through it. Therefore, from another perspective, the particulate material of this embodiment can be defined as follows. Within the distribution ratio of the particle brightness (based on the total number of particles (100%)), the brightness (A) at which the proportion of particles on the higher brightness side decreases to less than 1% compared to the peak brightness (P) is identified, and the brightness width (P-A=W) between this brightness (A) and the peak brightness (P) is calculated. In this embodiment, particles exhibiting peak brightness are considered to be single-layer MXene particles. Particles exhibiting a brightness (P±W) within 1 times the brightness width (W) relative to the peak brightness (P) are considered to be single-layer / few-layer MXene particles. Particles exhibiting a lower brightness (less than P-W and greater than P-3W) relative to the peak brightness (P) at a brightness width greater than 1 times and less than 3 times the brightness width (W) are considered to be multilayer MXene particles (thicker than few-layer MXene particles). Particles that exhibit a low brightness (less than P-3W) relative to the peak brightness (P) at a brightness width (W) greater than three times the above are considered to be very thick particles (such particles may be, but are not limited to, very thick MXene particles and / or MAX particles). The particulate material of this embodiment, including the above-mentioned MXene particles 10, may satisfy the following (IV) and, depending on the circumstances, may satisfy at least one of the above-mentioned (I) to (III).

[0101] (IV) In the distribution ratio of the brightness of particles of the particulate material (taking the total number of particles as 100%), the brightness (A) at which the ratio of specific particles decreases to less than 1% on the high brightness side compared to the peak brightness (P), the brightness width (P-A=W) between the brightness (A) and the peak brightness (P) is obtained, and the total ratio of particles showing a smaller brightness (less than P-3W) than three times the brightness width (W) relative to the peak brightness (P) is less than 0.1%.

[0102] Satisfying the above (IV) means that the proportion of very thick particles in the particulate material is less than 0.1%. The particulate material does not actually contain very thick particles, which is extremely important for obtaining a conductive film with high orientation of MXene particles. For example, if 1000 MXene particles with a thickness of 1nm are stacked to form a conductive film with a thickness of 1μm, if one of the 1000 particles (i.e., 0.1%) is a very thick particle, the orientation of the resulting conductive film will be significantly reduced. In contrast, by satisfying the above (IV), the proportion of very thick particles in the particulate material is less than 0.1%, thereby obtaining a conductive film with high orientation of MXene particles.

[0103] Regarding (IV) above, the distribution ratio of the brightness of particles of the particulate material is obtained as follows: using a particle image analyzer, a liquid composition (or slurry described later) containing the particulate material in a liquid medium is dropped onto a glass plate, covered with a cover glass, and illuminated with backlight. While performing image analysis on this transmitted light, the brightness of the transmitted light is measured, and the ratio (%) of the number of particles exhibiting a brightness within a specified range relative to the total number of particles is determined. The total number of particles measured is at least 10,000. The specified range of brightness when determining the brightness distribution can be appropriately selected, for example, it can be 10.

[0104] The slurry of this embodiment may be a dispersion and / or suspension containing the above-mentioned particulate matter in a liquid medium. The liquid medium may be an aqueous medium and / or an organic medium, preferably an aqueous medium. Aqueous medium is typically water, and depending on the circumstances, in addition to water, other liquid substances may also be contained in relatively small amounts (for example, 30% by mass or less, preferably 20% by mass or less, based on the overall standard of the aqueous medium). Organic medium may be, for example, N-methylpyrrolidone, N-methylformamide, N,N-dimethylformamide, ethanol, methanol, dimethyl sulfoxide, ethylene glycol, acetic acid, isopropyl alcohol, etc.

[0105] The concentration of the MXene particles 10 (including single-layer MXene particles 10a and multi-layer MXene particles 10b) in the slurry of this embodiment can be appropriately selected according to the application method of the slurry, but in order to ultimately obtain a conductive film with high orientation, it is preferably 10 mg / mL or more and 30 mg / mL or less. By setting it to 10 mg / mL or more, the single-layer MXene particles are easily oriented. By setting it to 30 mg / mL or less, the following problems can be avoided: (i) the viscosity of the slurry is high and difficult to handle (difficult to apply to the substrate); (ii) the thickness of the precursor formed once when the slurry is applied to the substrate is too thick; (iii) when the thick precursor is dried to remove the liquid medium, the liquid medium inside the precursor is rapidly vaporized, disrupting the orientation state of the MXene particles or forming large gaps. As described later, in order to obtain a conductive film with high orientation of MXene particles and a specified rocking curve half-maximum full width, it is preferred to set the MXene particle concentration in the slurry to 10 mg / mL or more and 30 mg / mL or less to suppress the orientation state disorder caused by the vaporization of the liquid medium. The concentration of the MXene particles 10 can be understood as the solid content concentration in the slurry. The solid content concentration can be measured, for example, using a heat-drying weight measurement method, a freeze-drying weight measurement method, a filtration weight measurement method, or the like.

[0106] In the slurry of this embodiment, the proportion of single-layer MXene particles 10a among the MXene particles 10 (monolayer MXene purity) is extremely high, and impurities other than the MXene particles 10 are low. In other words, the slurry of this embodiment can be understood as a highly purified MXene slurry. In the slurry of this embodiment, the MXene particles 10 are preferably highly dispersed without agglomeration.

[0107] The slurry of this embodiment can be obtained by performing a multi-stage centrifugal separation and supernatant recovery / separation operation on the crude refined MXene slurry after obtaining the crude refined MXene slurry. More specifically, the centrifugal separation and supernatant recovery operation is preferably performed in two or more stages, with the centrifugal separation and supernatant separation operation being performed in the final stage.

[0108] The crude MXene slurry is obtained by selectively etching A atoms from the MAX phase, centrifuging and separating the supernatant (recovering / cleaning the sediment), thereby roughly removing unnecessary components and adding a (fresh) liquid medium as needed. The crude refined slurry can contain desired single-layer MXene particles and multi-layer MXene particles that have not been monolayered due to insufficient layer separation (stratification). In addition, it can also contain impurities other than MXene particles (unreacted MAX particles and the above-mentioned by-products, etc.). In addition, layer separation (stratification) can be caused by applying a shear force greater than the molecular force acting between the MXene layers to the multilayer MXene. If the shear force is insufficient, the layers cannot be separated (monolayered). If the shear force is too large, the MXene is destroyed (divided into tiny MXenes), so it is important to apply appropriate shear force. As mentioned above, appropriate shear force can be applied by shaking manually or using an automatic shaker.

[0109] The crudely refined MXene slurry is subjected to multi-stage operations of centrifugation and supernatant recovery / separation removal (addition of (fresh) liquid medium as needed), thereby obtaining a highly purified MXene slurry of the present embodiment.

[0110] Figure 3 The following is an example of a case where the crude MXene slurry is subjected to centrifugal separation and supernatant recovery in one step. Figure 3 (a) A crude MXene slurry is prepared, and the MXene slurry contains single-layer MXene particles 10a and multi-layer MXene particles 10b as MXene particles 10, and impurities (unreacted MAX particles and the above-mentioned by-products, etc.) 15 in a liquid medium 19. After centrifugation, Figure 3As shown in (b), the crude refined slurry is roughly separated into a supernatant rich in monolayer MXene particles and a sediment rich in multilayer MXene particles and impurities 11. (Among the impurities, unreacted MAX particles are heavier, just like multilayer MXene particles, and therefore tend to sink more easily than monolayer MXene particles. Among the impurities, A1F3 is heavier (the specific gravity of A1F3 is 3g / cm 3 ), and its shape is also considered to be granular, so it tends to sink more easily than single-layer MXene particles. In addition, when AlF3 exists between the layers of multi-layer MXene particles, it is believed that they will sink together. On the other hand, single-layer MXene particles tend to be difficult to sink due to their two-dimensional shape with a large aspect ratio. Figure 3 (c) The supernatant is recovered by decantation or the like, and fresh liquid medium is added as needed to obtain Figure 3 (d) shows the slurry after the one-stage operation. The slurry after the one-stage operation is different from the crude refined slurry before the operation ( Figure 3 (a)), the multilayer MXene particles 10b and impurities (unreacted MAX particles and the above-mentioned by-products, etc.) 15 are effectively reduced. Such centrifugation and supernatant recovery operations are carried out in two or more stages. Then, in the final stage, after centrifugation, the supernatant is separated and removed by decantation or the like. For the remaining sediment, fresh liquid medium is added as needed, thereby obtaining a highly purified MXene slurry of the present embodiment. In the supernatant separated and removed in the final stage, because a large amount of tiny MXene particles are distributed, the MXene slurry of the present embodiment finally obtained has tiny MXene particles more effectively reduced than the MXene slurry before the final stage operation. Based on the above, a highly purified MXene slurry of the present embodiment containing a high proportion of single-layer MXene particles can be obtained.

[0111] Theoretically, during centrifugation, the particles that settle are roughly determined by the centrifugal force and time. Therefore, whether centrifugation is performed in only one stage or in multiple stages, if the centrifugal force and the total time are the same, it can be understood that the supernatant recovered after centrifugation will be in the same state. However, in reality, when the supernatant (a portion with a large amount of monolayer MXene particles) is recovered after centrifugation, the sediment (multilayer MXene particles and impurities) is stirred and rises and mixed into the supernatant. Therefore, when centrifugation is performed in only one stage, it can be seen that the supernatant recovered after centrifugation is in a different state than when centrifugation is performed in multiple stages. As described above, by performing centrifugation and supernatant recovery / separation and removal operations in multiple stages, a highly purified MXene slurry of the present embodiment can be obtained. As described later, in order to obtain a conductive film with high orientation of MXene particles and a specified rocking curve half-maximum full width, it is preferred to perform centrifugation and supernatant recovery / separation and removal operations in multiple stages to obtain a MXene slurry with high purity of monolayer MXene. The total number of times the multi-stage centrifugation and supernatant recovery / separation and removal operations are performed is 2 or more, preferably 3 or more.

[0112] In this embodiment, the centrifugal force and time of centrifugal separation can be appropriately set. The centrifugal force can be, for example, a relative centrifugal force (RCF) of 3000×g or more and 4500×g or less. By setting the RCF to 4500×g or less, it is possible to suppress the destruction of the monolayer MXene particles. By setting the RCF to 3000×g or more, it is possible to effectively separate the monolayer MXene particles from the multilayer MXene particles and impurities. The time of centrifugal separation can be, for example, 3 minutes or more and 60 minutes or less. By setting the RCF to 60 minutes or less, it is possible to suppress the aggregation of MXene particles or the multilayering of the monolayer MXene particles. By setting the RCF to 3 minutes or more, it is possible to effectively separate the monolayer MXene particles from the multilayer MXene particles and impurities. In addition, in a multi-stage operation, if the centrifugal force of the centrifugal separation is set to the same, the time of centrifugal separation can be set to be longer as the stage progresses. However, it should be noted that if the centrifugal separation time is too long, the monolayer MXene particles will be compressed for a long time and will multilayer again.

[0113] The conductive film 30 of this embodiment can be produced using the MXene slurry of this embodiment adjusted as described above.

[0114] Reference Figure 4 The method for manufacturing the conductive film 30 of this embodiment includes:

[0115] (a) applying (supplying or coating) the slurry of this embodiment on a substrate 31 to form a precursor of a conductive film 30 containing MXene particles, and

[0116] (b) Drying the precursor.

[0117] Process (a)

[0118] The substrate 31 only needs to have a flat surface 31a (see Figure 1 ), there is no particular limitation and any appropriate material may be used. The substrate may be, for example, a resin film, metal foil, a printed circuit board, a mounted electronic component, a metal pin, a metal wiring, a metal wire, etc. If the substrate 31 does not have a flat surface, such as a filter membrane, the orientation of the conductive film formed thereon becomes low and the surface of the conductive film becomes rough, so it is not preferred. The surface 31a of the substrate 31 only needs to be at or above the same level as the desired surface smoothness of the conductive film 30, and typically, it can have an arithmetic mean roughness of 120nm or less.

[0119] As described later, in order to obtain the conductive film 30 of this embodiment with highly oriented MXene particles and a predetermined full width at half maximum of the rocking curve, it is preferred that the MXene slurry of this embodiment be sufficiently wetted and spread on the substrate surface 31a. When the MXene slurry contains an aqueous medium, the substrate surface 31a may be pre-treated to hydrophilize the surface to improve wettability.

[0120] The method of applying the slurry of the present embodiment to the substrate 31 is as long as the conductive film 30 of the present embodiment with high orientation of MXene particles can be obtained. More specifically, the application of the slurry can be implemented by spraying, spin coating or scraping, and by stacking the MXene particles well and reducing the distance between the MXene particles, a conductive film 30 with high orientation, density (high density) and smooth surface can be obtained. Among them, spraying can apply the slurry of the present embodiment (containing MXene particles 10 and liquid medium) thinly to the substrate 31 (forming a thin precursor), so that the MXene particles 10 can be supplied in a state of being oriented as parallel as possible (flat arrangement) relative to the substrate surface 31a, so it is preferred (in this case, the surface tension of the liquid medium can also preferably play a role). The nozzle used for spraying is not particularly limited.

[0121] Process (b)

[0122] Thereafter, the precursor on the substrate 31 is dried. In the present invention, "drying" means removing the liquid medium present in the precursor.

[0123] Drying can be carried out under mild conditions such as natural drying (typically at room temperature and pressure, in an air atmosphere) or air drying (spraying air), or under relatively intense conditions such as warm air drying (spraying heated air), heat drying, and / or vacuum drying.

[0124] Step (a) (formation of the precursor) and step (b) (drying) are preferably repeated a total of more than 2 times until the desired conductive film thickness can be obtained. In other words, in step (a), a small amount of slurry is applied to the substrate 31 to form a precursor, and in step (b), the precursor is dried, and such operation is preferably repeated multiple times. In order to obtain a conductive film 30 with higher orientation, in step (a), it is preferably to apply a small amount of slurry to form a thin precursor, so that the MXene particles 10 can be supplied in a state as parallel as possible to the substrate surface 31a. In addition, in step (b), it is preferably to fully dry the thin precursor each time until there is substantially no liquid medium remaining, so that when the liquid medium is dried and removed from the precursor, the supply state (orientation state) of the MXene particles 10 is not disturbed as much as possible (so as not to form large gaps).

[0125] For example, the combination of spraying and drying can be repeated multiple times. Figure 4 As shown in (a), a small amount of slurry is sprayed from the nozzle 20 onto the substrate surface 31 as a mist M (indicated by a dotted line in the figure) to form a precursor layer (first layer) 29a containing MXene particles in a liquid medium. Figure 4 As shown in (b), heated air is sprayed from the warm air dryer 21 in the direction toward the precursor layer 29a on the substrate surface 31a (indicated by a dotted arrow in the figure) to dry it, and the liquid medium is removed from the precursor layer 29a to form a conductive layer (first layer) 30a containing MXene particles. Repeating such spraying and drying forms a conductive film 30 in which multiple conductive layers 30a, 30b, 30c... (not shown) are stacked. The thickness of the conductive layer formed by the spraying and drying is not particularly limited, for example, it can be greater than 0.01μm and less than 1μm. The number of repetitions of spraying and drying can be appropriately selected according to the required thickness of the conductive film 30.

[0126] The conductive film 30 of this embodiment can be manufactured in this manner. The conductive film 30 includes the MXene particles 10 and preferably contains substantially no residual liquid medium of the slurry of this embodiment. The conductive film 30 does not contain a so-called binder.

[0127] like Figure 1As schematically shown, the resulting conductive film 30 contains MXene particles 10 in a relatively uniform and aligned state. More specifically, a large number of particles 10 have their two-dimensionally developed planes (planes parallel to the MXene layer) relatively aligned (preferably parallel) with respect to the substrate surface 31a (in other words, the main surface of the conductive film 30). This results in a conductive film 30 with highly oriented MXene particles 10. This conductive film 30 achieves surface contact between the MXene particles 10, resulting in good contact and high electrical conductivity.

[0128] The conductive film 30 of this embodiment is subjected to X-ray diffraction measurement, and the full width at half maximum of the x-axis direction rocking curve associated with the peak of the (00I) plane (I is a natural number multiple of 2) is 10.3° or less.

[0129] The present invention is not bound by any theory, but the conductive film containing MXene particles can be formed by stacking MXene particles (collectively referred to as single-layer MXene particles and multi-layer MXene particles, and single-layer MXene particles can also be referred to as "nanosheets" or "monoliths"), and the conductivity of such a conductive film can be considered to be dominated by the orientation of the MXene particles. In order to obtain a conductive film with high conductivity, it is preferred that the MXene particles are oriented as parallel and uniformly as possible to each other. In other words, it is preferred that the orientation is high. As a measure of the orientation of MXene particles, the full width at half maximum of the x-axis rocking curve associated with the peak of the (00I) plane (I is a natural number multiple of 2) obtained by X-ray diffraction measurement can be applied (hereinafter also referred to as "the full width at half maximum of the x-axis rocking curve"). The narrower the full width at half maximum of the x-axis rocking curve, the higher the orientation of the MXene particles in the conductive film.

[0130] The full width at half maximum of the rocking curve in the x-axis direction is obtained by performing X-ray diffraction (XRD) measurement on a conductive film, and is obtained from the peak of the (00I) plane (I is a natural number multiple of 2, that is, 1=2, 4, 6, 8, 10, 12...) of the MXene contained in the conductive film. More specifically, it is determined as follows. If an XRD measurement is performed on a conductive film containing MXene, the peak of the (00I) plane of MXene can be observed in the XRD line shape obtained by scanning the θ axis. In the XRD line shape of the θ axis scan, the peak of the (00I) plane of MXene can be observed multiple times. Although any peak can be used, the peak of the (0010) plane (I=10) can be used representatively. Then, based on the x-axis scan fixed at 2θ from which the peak of the (00I) plane is obtained, the x-axis rocking curve can be obtained. One peak is observed in the x-axis rocking curve, and the width (°) of the x-axis angle when the intensity of the peak reaches half is referred to as the "full width at half maximum of the x-axis rocking curve."

[0131] In XRD measurement, for example, a micro-X-ray diffraction (μ-XRD) apparatus equipped with a two-dimensional detector can be used to convert the resulting two-dimensional X-ray diffraction pattern into one dimension (suitably for fitting), thereby obtaining an XRD profile for the θ-axis scan (with intensity on the vertical axis and 2θ on the horizontal axis, generally referred to as an "XRD line shape") and a rocking curve profile for the χ-axis scan (with intensity on the vertical axis and χ on the horizontal axis) about a specified 2θ.

[0132] The (00I) plane of MXene basically represents the crystal c-axis orientation of MXene, and the peak of the (00I) plane can be observed in the XRD line shape of the θ-axis scan. In addition, in the XRD line shape of the θ-axis scan, the peak of the (00I) plane can be observed in θ corresponding to the length d of the periodic structure of MXene (the periodic structure along the stacking direction in the stacking structure of single-layer MXene and / or multi-layer MXene). According to the Bragg diffraction condition (2d·sinθ=n·λ (n is a natural number, λ is a wavelength)), the length d of the periodic structure will be offset according to the interlayer distance of MXene (referring to the distance between any two adjacent MXene layers in the conductive film, regardless of single-layer MXene and multi-layer MXene), and the thickness of the MXene layer. In the above formula: M m X n In the case of MXene represented by Ti3C2, the peak of the (0010) plane is observed as a peak near 2θ=35~40° (about 36°). If the χ-axis rocking curve is obtained for the peak of the (00I) plane, the intensity reaches a maximum (observable peak) at an angle perpendicular to the main surface of the conductive film (or near it). The more consistent the crystal c-axis orientation of the MXene, the more significant the decrease in intensity when it deviates from the above-mentioned perpendicular angle. Therefore, the smaller the half-maximum full width of the peak in the χ-axis rocking curve, the more consistent the crystal c-axis orientation of the MXene, in other words, the higher the orientation (refer to Figure 1 ).

[0133] The conductive film of this embodiment has a x-axis rocking curve full width at half maximum of 10.3° or less, indicating high MXene particle orientation. This allows for high conductivity, for example, 10,000 S / cm or greater. The x-axis rocking curve full width at half maximum is preferably 8.8° or less, thereby achieving even higher conductivity. There is no particular lower limit for the x-axis rocking curve full width at half maximum; for example, it can be 3° or greater.

[0134] Specifically, the conductive film of this embodiment can have an electrical conductivity of 12,000 S / cm or greater. The electrical conductivity of the conductive film is preferably 14,000 S / cm or greater, with no particular upper limit, but can be, for example, 30,000 S / cm or less. The electrical conductivity can be calculated from the measured resistivity and thickness of the conductive film.

[0135] Furthermore, in the conductive film of this embodiment, since the full width at half maximum of the x-axis rocking curve is 10.3° or less and the orientation of the MXene particles is high, a high density can be achieved. Specifically, a density of 3.00 g / cm 3 The density of the conductive film is preferably 3.40 g / cm. 3 There is no particular upper limit, but for example, it can be 4.5 g / cm 3 The density can be calculated by measuring the mass and thickness of a portion of a predetermined area within the conductive film and using these measured values.

[0136] Furthermore, in the conductive film of this embodiment, since the x-axis rocking curve full width at half maximum is 10.3° or less, the MXene particles are highly oriented, resulting in high surface smoothness. Specifically, an arithmetic mean roughness (Ra) of 120 nm or less can be achieved. High orientation and surface smoothness indicate that the conductive film is uniform and flat. Ra is preferably 100 nm or less, more preferably 80 nm or less, and there is no particular lower limit, but it can be, for example, 1 nm or more. Ra can be measured on the exposed surface of the conductive film using a surface roughness meter.

[0137] The conductive film of this embodiment can have a so-called thin film form, specifically, can have two main surfaces facing each other. The thickness, shape and size of the conductive film in plan view can be appropriately selected according to the application of the conductive film.

[0138] The conductive film of this embodiment can be applied to any appropriate application and is preferably used as an electromagnetic shield (EMI shield) requiring high electrical conductivity.

[0139] By using the conductive film of this embodiment, electromagnetic shielding with a high shielding rate (EMI shielding property) can be obtained. Generally, EMI shielding property is calculated as shown in Table 1 based on the following formula (1) with respect to the electrical conductivity.

[0140] [Formula 1]

[0141]

[0142] In formula (1), SE is the EMI shielding performance (dB), σ is the electrical conductivity (S / cm), f is the frequency of the electromagnetic wave (MHz), and t is the thickness of the film (cm).

[0143]

Table 1

[0144] Conductivity (s / cm) EMI shielding (dB)* 100 41 1,000 52 5,000 61 10,000 65 12,000 67 14,000 68

[0145] *Where, f = 1000 MHz, t = 0.001 cm.

[0146] As can be seen from Table 1, a conductivity of 10,000 S / cm or greater can achieve high EMI shielding properties. The conductive film of this embodiment has a conductivity of 10,000 S / cm or greater, preferably 12,000 S / cm or greater. Therefore, even with a constant thickness, higher EMI shielding properties can be achieved, and a sufficient EMI shielding effect can be achieved even with a reduced thickness.

[0147] While the conductive film, slurry, and method for producing a conductive film using the slurry according to one embodiment of the present invention have been described in detail above, various modifications are possible. Furthermore, the conductive film of the present invention can be produced using methods other than the production method of the aforementioned embodiment. Furthermore, it should be noted that the method for producing a conductive film of the present invention is not limited to providing the conductive film of the aforementioned embodiment.

[0148] Example

[0149] (Comparative Example 1 and Examples 1-2: MXene slurry)

[0150] Preparation of MXene slurry

[0151] The MXene slurries of Comparative Example 1 and Examples 1-2 were prepared according to the following steps.

[0152] TiC powder, Ti powder, and Al powder (all manufactured by Kojundo Chemical Laboratory Co., Ltd.) were placed in a ball mill containing zirconia balls at a molar ratio of 2:1:1 and mixed for 24 hours. The resulting mixed powder was sintered at 1350°C for 2 hours under an Ar atmosphere. The resulting sintered body (green body) was crushed with an end mill to a maximum size of 40 μm or less. This yielded Ti3Al1C2 particles (powder) as MAX particles.

[0153] The Ti3AlC2 particles (powder) obtained above were added to 9 mol / L hydrochloric acid together with LiF (1g of Ti3AlC2 particles, 1g of LiF, and 10mL of 9 mol / L hydrochloric acid). The mixture was stirred at 35°C for 24 hours with a stirrer to obtain a solid-liquid mixture (suspension) containing solid components from the Ti3AlC2 particles. The operation of washing with pure water and separating and removing the supernatant by decantation using a centrifuge (the remaining sediment after removing the supernatant was washed again) was repeated about 10 times. Then, the mixture with pure water added to the sediment was stirred with an automatic shaker for 15 minutes. Thus, a crude refined MXene slurry was obtained.

[0154] The crude MXene slurry obtained above was placed in a 50 mL centrifuge tube and centrifuged at an RCF of 3500 × g for 3 minutes using a Sorvall Legend XT, manufactured by Thermo Fisher Scientific. The same applies hereafter. The supernatant from this centrifugation was recovered by decantation to obtain the MXene slurry after the first stage of the operation. The remaining sediment after the supernatant was removed and subsequently discarded.

[0155] The MXene slurry after the first stage operation was placed in a 50 mL centrifuge tube and centrifuged at an RCF of 3500 × g for 15 minutes using a centrifuge. The supernatant from the centrifugation was recovered by decantation to obtain the MXene slurry after the second stage operation. The remaining sediment (high-concentration slurry) after removing the supernatant was diluted by adding pure water to obtain the MXene slurry of Comparative Example 1 (solid content concentration 15 mg / mL).

[0156] The MXene slurry after the second stage operation was added to a 50 mL centrifuge tube and centrifuged at an RCF of 3500 × g for 30 minutes using a centrifuge. The supernatant from the centrifugation was recovered by decantation to obtain the MXene slurry after the third stage operation. The remaining sediment (high-concentration slurry) after removing the supernatant was diluted by adding pure water to obtain the MXene slurry of Example 1 (solid content concentration 15 mg / mL).

[0157] The MXene slurry after the three-stage operation was added to a 50 mL centrifuge tube and centrifuged at an RCF of 3500 × g for 45 minutes using a centrifuge. The supernatant thus centrifuged was separated and removed by decantation. The supernatant that was separated and removed was no longer used. The remaining sediment (high concentration slurry) after removing the supernatant was diluted by adding pure water to obtain the MXene slurry of Example 2 (solid content concentration 15 mg / mL).

[0158] Evaluation of MXene slurry

[0159] For the MXene slurries of Comparative Example 1 and Examples 1-2 prepared in the above manner, a particle image analyzer ("Morphologi4", manufactured by Malvern Panalytical) was used to drop a sample of MXene slurry on a glass plate, cover it with a cover glass, and irradiate the sample with backlight. The image of the transmitted light was analyzed to investigate the equivalent circular diameter (μm) represented by the particle size (which can be considered as the size of the two-dimensional expanded surface in MXene particles) and the brightness distribution of the particles. The results are shown in Figures 5-7 (Also, since particles can move during the shooting of particle images, it is believed that the equivalent circle diameter is slightly overestimated). In addition, based on these results, the brightness distribution ratio of the particles (the ratio of the number of particles with brightness within a specified range based on the total number of particles (100%)) is investigated. The specified range is set to 10, and the brightness is 60 or less, higher than 60 and lower than 70, higher than 70 and lower than 80, ..., higher than 180 and lower than 190, higher than 190 and lower than 200, and higher than 200. For example, particles with a brightness higher than 120 and lower than 130 are marked as particles with brightness "130". The results are shown in Figure 8 The brighter particles are thinner particles, that is, they can be considered as single-layer MXene particles, and the smaller particles are thicker particles, that is, they can be considered as multi-layer MXene particles and impurities (unreacted MAX particles and by-products, which can exist between the layers of multi-layer MXene particles). The results shown in the figure show that compared with the MXene slurry of Comparative Example 1 ( Figure 5 ) compared to the MXene slurry of Example 1 ( Figure 6 ), almost no particles with a brightness of less than 100 (i.e., a relatively large thickness) are seen, which indicates that highly refined single-layer MXene particles can be achieved. Figure 7 ), almost no particles with brightness below 120 (i.e., thick particles) can be seen, which can be understood as being able to achieve a higher degree of purification of single-layer MXene particles. Figures 5 to 8 The results shown are comparable because they were measured under the same conditions, but it should be noted that the absolute value of brightness depends on the intensity of the backlight.

[0160] Reference Figure 8(a) The peak brightness (P) is 170, and the brightness (A) at which the particle ratio decreases to less than 1% on the higher brightness side is 190. Therefore, the brightness width (P-A=W) between this brightness (A) and the peak brightness (P) is 20. Particles that exhibit a brightness within 1 times the brightness width (W=20) relative to the peak brightness (P=170) (P±W=150 or more and 190 or less) are considered to be single-layer / few-layer MXene particles. Particles that exhibit a low brightness greater than 1 times and less than 3 times the brightness width (W=20) relative to the peak brightness (P=170) (less than P-W and at least P-3W=110 or more and less than 150) are considered to be multilayer MXene particles (thicker than few-layer MXene particles). Particles that show a lower brightness (less than P-3W = less than 110) than 3 times the brightness width (W = 20) relative to the peak brightness (P = 170) can be considered to be very thick particles. Figure 8 In the brightness distribution shown, since the prescribed range of brightness is 10, the minimum brightness (less than P-3W = less than 110) which is 3 times higher than the brightness width (W = 20) relative to the peak brightness (P = 170) is less than 100. Figure 8 (b) In the MXene slurry of Comparative Example 1, the proportion of particles with a brightness of 100 is 0.1% or more, specifically 0.13%, and the proportion of particles with a brightness of less than 100 is 0.1% or more, specifically 0.35%. In contrast, in the MXene slurries of Examples 1 and 2, the proportion of particles with a brightness of 100 is less than 0.1%, specifically 0.01%, and the proportion of particles with a brightness of less than 100 is less than 0.1% in total, specifically 0.01%.

[0161] In addition, for the MXene slurries of Comparative Example 1 and Examples 1 to 2 prepared according to the above method, the samples (solid content concentrations are as described above) are dropped on a silicon wafer (arithmetic mean roughness Ra is less than 0.5 nm), dried, and the thickness of the particles contained in the sample is measured using AFM. The size of the field of view is 30 μm × 30 μm, and the heights of all particles in one field of view (but as described above) are measured until the measurement results of at least 40 particles are obtained, and different fields of view are set in the same way. The results are shown in Tables 2 and 3. For example, in Example 1, the thickness of 8 particles present in field of view 1 is measured, and then the thickness of 8 particles present in field of view 2 is measured, ... (fields of view 3 to 5), and then the thickness of 6 particles present in field of view 6 is measured, and the thickness measurement results of a total of 42 particles are obtained.

[0162]

Table 2

[0163]

[0164]

Table 3

[0165]

[0166] Referring to Tables 2-3, in the MXene slurry of Comparative Example 1, out of a total of 48 particles, 3 particles had a thickness exceeding 20 nm, resulting in a proportion of 6% of the particulate material with a thickness exceeding 20 nm. In the MXene slurry of Comparative Example 1, the maximum thickness of the particles contained in the particulate material exceeded 500 nm, and particles with a thickness exceeding 500 nm are considered MAX particles. In contrast, in the MXene slurry of Example 1, out of a total of 42 particles, 0 particles had a thickness exceeding 20 nm, resulting in a proportion of 0% of the particulate material with a thickness exceeding 20 nm. In the MXene slurry of Example 1, the maximum thickness of the particles contained in the particulate material was approximately 13 nm, with only one particle having a thickness exceeding 10 nm; all other particles had a thickness of 10 nm or less. In the MXene slurry of Example 2, out of a total of 51 particles, 0 particles had a thickness exceeding 20 nm, resulting in a proportion of 0% of the particulate material with a thickness exceeding 20 nm. In the MXene slurry of Example 2, the maximum thickness of the particles contained in the particulate material was approximately 14 nm. Only one particle had a thickness exceeding 10 nm, and all other particles were less than 10 nm thick. Particles with a thickness of 15 nm or less were considered single-layer or few-layer MXene particles, and particles with a thickness of 4 nm or less were considered single-layer MXene particles.

[0167] The thickness distribution of the particles measured by AFM shown in Table 3 can be confirmed to be Figure 8 The distribution ratio of the brightness shown is roughly corresponding to that measured by a particle image analysis device ("Morphologi4"). Figure 8 Particles showing brightness of 150 or more and 190 or less are considered to be single-layer or few-layer MXene particles, which can be considered to correspond to particles with a thickness of 10nm or less in AFM measurement. Figure 8 Particles showing a brightness of more than 110 and less than 150 are considered to be multilayer MXene particles (thicker than few-layer MXene particles), which can be considered to correspond to particles with a thickness greater than 10 nm and less than 30 nm in AFM measurements. Figure 8 Particles showing a brightness lower than 110 (below 100) are considered to be very thick particles, which can be considered to correspond to particles larger than 30 nm in AFM measurement.

[0168] In addition, for the MXene slurries of Comparative Example 1 and Examples 1-2 prepared in the above manner, the samples (solid content concentrations were as described above) were dried and the contents of Ti and Al were measured using ICP-AES. Based on these measured values, the ratio of Al to Ti (mol %) was calculated. The results are shown in Table 4. The lower the ratio of Al to Ti, the lower the number of multilayer MXene particles and impurities (unreacted MAX particles and by-products). Therefore, it is believed that the proportion of single-layer MXene particles in the MXene particles is high.

[0169]

Table 4

[0170] Comparative Example 1 Example 1 Example 2 Al / Ti (mol%) 1.79 0.27 0.15

[0171] As shown in Table 4, the ratio of Al to Ti (mol %) in the MXene slurry of Example 1 is lower than that of the MXene slurry of Comparative Example 1 (more specifically, the ratio of Al to Ti in the slurry is 0.30 mol % or less), which can be understood as enabling highly refined single-layer MXene particles. Furthermore, the ratio of Al to Ti (mol %) in the MXene slurry of Example 2 is further reduced, which can be understood as enabling even more highly refined single-layer MXene particles.

[0172] (Comparative Example 2 and Examples 3 and 4: Conductive Films)

[0173] ·Production of conductive film

[0174] Conductive films (MXene films) of Comparative Example 2 and Examples 3 and 4 were prepared using the following procedures. The conductive film of Comparative Example 2 used the MXene slurry of Comparative Example 1, and the conductive films of Examples 3 and 4 used the MXene slurries of Examples 1 and 2, respectively. The following procedures were used to prepare the conductive films.

[0175] Each MXene slurry prepared as described above was diluted by adding pure water to prepare a slurry having a solid content concentration of approximately 15 mg / mL.

[0176] A 50 μm thick polyethylene terephthalate film that had been subjected to a hydrophilic surface treatment (ultraviolet-ozone treatment) was prepared as a substrate. A 3 cm x 3 cm square area was left exposed on the substrate surface, and the surrounding area was masked with scotch tape.

[0177] The slurry prepared as described above (solid content concentration of 15 mg / mL) is sprayed onto the above-mentioned substrate using a spray gun (manufactured by Tamiya Co., Ltd., Spray Work HG spray gun (trigger type), spray gun system No. 53 Spray Work Power Compressor 74553) at an air pressure of 0.40 MPa (absolute pressure). After spraying, it is dried by spraying warm air with a handheld dryer (manufactured by Panasonic Corporation, EH5206P-A). The thickness of each layer of the precursor formed by spraying is several tens of nm. After spraying a layer of the precursor, it is fully dried by spraying warm air (the temperature of the substrate during drying is considered to be above 40°C, which can effectively promote drying). Such spraying and drying operations are repeated more than 100 times in total. Thereafter, it is dried in a vacuum oven at 80°C for 16 hours. Thus, a conductive film with a thickness of 3 to 5 μm is produced on a square area of ​​3 cm × 3 cm on the substrate. Furthermore, on the transparent tape applied to the substrate, the sprayed mist was blocked, so that no conductive film was formed.

[0178] Evaluation of conductive films

[0179] The conductive films of Comparative Example 2 and Examples 3 and 4 produced above were evaluated with respect to the following items.

[0180] χ axial rocking curve full width at half maximum

[0181] The conductive film with a substrate (sample) prepared above was punched or cut from each substrate and subjected to XRD measurement using μ-XRD (manufactured by Bruker Corporation, AXS D8 DISCOVER with GADDS), and the full width at half maximum of the x-axis rocking curve was calculated. More specifically, the XRD measurement obtained a two-dimensional X-ray diffraction image of the conductive film (characteristic X-ray: CyKα = 1.54), and the peak at 2θ = 35 to 40° (near 36°) in the XRD line shape of the θ-axis scan was examined (Formula: M m X n The X-axis rocking curve was calculated for the peak (the peak of the (0010) plane of the MXene represented by Ti3C2). The full width at half maximum of the X-axis rocking curve was calculated. The full width at half maximum of the X-axis rocking curve is the average of the two measured values ​​obtained during the XRD measurement. The results are shown in Table 5 (in Table 5, the full width at half maximum of the X-axis rocking curve is simply expressed as "full width at half maximum").

[0182] Conductivity

[0183] In addition, among the conductive films with substrates (samples) produced above, the unpunched parts (the same applies below) were used to measure the conductivity (S / cm) of the conductive films. More specifically, for the conductivity, the resistivity (surface resistivity) (Ω) and the thickness (minus the thickness of the substrate) (μm) were measured 3 times each at 5 locations, including the four corners and the center, for one sample. The conductivity (S / cm) was calculated from the average value of the 3 measurements, and the average value of the conductivity at the 5 locations obtained was used. For the resistivity measurement, a low resistivity meter (LorestaAX MCP-T370, manufactured by Mitsubishi Chemical Analytical Technology Co., Ltd.) was used. For the thickness measurement, a micrometer (MDH-25MB, manufactured by Mitutoyo Co., Ltd.) was used. The results are shown in Table 5.

[0184] density

[0185] The conductive film with a substrate (sample) prepared above was cut out at a total of five locations in an area of ​​1 cm × 1 cm, the same as the thickness measurement above. The weight of the cut portion was measured before and after the conductive film was peeled off. The weight per unit area (1 cm) was calculated as the difference between the measured values. 2 ) of the conductive film. Then, the unit area (1cm 2 The density of the conductive film was calculated by dividing the mass of the conductive film by the thickness obtained by the above thickness measurement. The results are shown in Table 5.

[0186] Ra (arithmetic mean roughness)

[0187] The exposed surface of the conductive film with a substrate (sample) prepared above was measured for Ra (arithmetic mean roughness) at three locations using a surface roughness measuring instrument with a white light interferometer system (NewView 7300, manufactured by ZYGO Corporation). The average of the three Ra values ​​was used. The results are also shown in Table 5.

[0188]

Table 5

[0189] Comparative Example 2 Example 3 Example 4 MXene slurry Comparative Example 1 Example 1 Example 2 Full width at half maximum (°) 13.2 10.3 8.8 Conductivity (S / cm) 8300 12900 14600 <![CDATA[Density (g / cm 3 )]]> 2.54 3.37 3.50 Ra(nm) 314 118 74

[0190] Observation of the appearance of the conductive film

[0191] For the conductive film with a substrate (sample) prepared as described above, a label with color and characters on the label surface is placed so that the label surface is tilted opposite to the exposed surface of the conductive film (with an inner angle of about 45°), and the reflection of the label surface facing the exposed surface of the conductive film is observed. On the label surface, (i) black areas, (ii) areas with black characters on a white background, (iii) areas with white and black characters on a green background, and (iv) areas with green and black characters on a white background are arranged parallel to each other. The higher the degree of reflection on the conductive film, the higher the light reflectivity, indicating a higher orientation. In the conductive film of Comparative Example 2, the reflection of the label surface is almost not seen, and it is to the extent that (i) black areas, (ii) white areas, (iii) green areas, and (iv) white areas can be barely distinguished. In the conductive film of Example 3, the reflection of the label surface can be seen, and it can be distinguished that (i) black areas, (ii) white areas have faint black characters, (iii) green areas have faint white and black characters, and (iv) white areas have faint green and black characters. In the conductive film of Example 4, the reflection of the label surface can be clearly seen, and (i) the black area, (ii) the area with black characters in white, (iii) the area with white and black characters in green, and (iv) the area with green and black characters in white can be clearly distinguished.

[0192] Cross-sectional SEM observation of the conductive film

[0193] The conductive film with a substrate (sample) prepared above was cut in the thickness direction, and the cross section was observed using a scanning electron microscope (SEM) (S-5000, manufactured by Hitachi, Ltd.). The cross section SEM photograph of the sample is shown in FIG. Figures 9-11 middle. Figures 9-11 31. The conductive film 30 is formed on the substrate 31. As can be seen from the results shown in the figure, the conductive film of Comparative Example 2 ( Figure 9 ), the presence of particulate crystalline impurities can be confirmed (refer to the area surrounded by the dotted line in the figure). In addition, since multilayer MXene particles (not shown) exist in the conductive film, the layer structure of MXene is quite disordered. In addition, the particulate crystalline impurities observed in the SEM photograph are believed to be unreacted MAX particles (or multilayer MXene particles that have not been delaminated) (although it is considered that there is a high possibility that A1F3 exists between the layers of the multilayer MXene particles, it is believed that it does not have a size that can be easily detected by SEM). In the conductive film of Example 3 ( Figure 10 ), it can be confirmed that there are granular crystalline impurities (see the area surrounded by dotted lines in the figure), which hinder the stacking of single-layer MXene particles, but the single-layer MXene particles are generally well oriented and stacked. In addition, in the conductive film of Example 4 ( Figure 11), no disorder of the MXene layer structure was observed, and the single-layer MXene particles were stacked with extremely high orientation.

[0194] Industrial applicability

[0195] The conductive film of the present invention can be used for any appropriate purpose, and can be particularly preferably used as an electromagnetic shield, for example.

[0196] This application claims priority based on Japanese Patent Application No. 2020-136819 filed in Japan on August 13, 2020, the entire contents of which are incorporated herein by reference.

[0197] Explanation of symbols

[0198] 1a, 1b layer main body (M m X n layer)

[0199] 3a, 5a, 3b, 5b modification or terminal T

[0200] 7a, 7b MXene layers

[0201] 10, 10a, 10b MXene (layered material) particles

[0202] 19 Impurities

[0203] 20 nozzles

[0204] 21 Warm air dryer

[0205] 29a Precursor layer (1st layer)

[0206] 30 conductive film

[0207] 30a conductive layer (first layer)

[0208] 31 substrate

[0209] 31a Substrate surface

Claims

1. A conductive film comprising particles of a layered material having one or more layers, wherein: The layers include: By the following formula: M m X n The layer body represented by Wherein, M is at least one metal of Groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination of carbon and nitrogen atoms, n is 1 or more and 4 or less, m is greater than n and less than 5; The modification or terminal T present on the surface of the main body of the layer, 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 full width at half maximum of the x-axis direction rocking curve associated with the (00I) plane peak obtained by X-ray diffraction measurement of the conductive film is 10.3° or less, where I is a natural multiple of 2. The conductive film has an electrical conductivity of 10,000 S / cm or more.

2. The conductive film according to claim 1, wherein The full width at half maximum of the rocking curve in the x-axis direction is less than 8.8°.

3. The conductive film according to claim 1 or 2, wherein The conductive film has an electrical conductivity of 12,000 S / cm or more.

4. The conductive film according to claim 1 or 2, wherein The conductive film has a thickness of 3.00 g / cm 3 Density above.

5. The conductive film according to claim 1 or 2, wherein The conductive film has an arithmetic mean roughness of 120 nm or less.

6. The conductive film according to claim 1 or 2, wherein Used as electromagnetic shielding.

7. A conductive film formed of a particulate material comprising particles of a layered material having one or more layers, wherein: The layers include: By the following formula: M m X n The layer body represented by Wherein, M is at least one metal of Groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination of carbon and nitrogen atoms, n is 1 or more and 4 or less, m is greater than n and less than 5; The modification or terminal T present on the surface of the main body of the layer, 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 ratio of A to M in the particulate material is 0.30 mol % or less, A is at least one element of Groups 12, 13, 14, 15, and 16, The conductive film has an electrical conductivity of 10,000 S / cm or more.

8. The conductive film according to claim 7, wherein The M is Ti, and the A is Al.

9. A conductive film formed of a particulate material comprising particles of a layered material having one or more layers, wherein: The layers include: By the following formula: M m X n The layer body represented by Wherein, M is at least one metal of Groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination of carbon and nitrogen atoms, n is 1 or more and 4 or less, m is greater than n and less than 5; The modification or terminal T present on the surface of the main body of the layer, 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 proportion of particles having a thickness greater than 20 nm in the particulate material is less than 2%, The conductive film has an electrical conductivity of 10,000 S / cm or more.

10. A conductive film formed of a particulate material comprising particles of a layered material having one or more layers, wherein: The layers include: By the following formula: M m X n The layer body represented by Wherein, M is at least one metal of Groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination of carbon and nitrogen atoms, n is 1 or more and 4 or less, m is greater than n and less than 5; The modification or terminal T present on the surface of the main body of the layer, 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 maximum thickness of the particles contained in the particulate material is 500 nm or less, The conductive film has an electrical conductivity of 10,000 S / cm or more. The conductive film according to claim 10 , wherein The proportion of particles having a thickness exceeding 20 nm in the particulate material serving as a raw material for the conductive film is less than 2%.

12. The conductive film according to any one of claims 9 to 11, wherein The ratio of A to M in the particulate material is 0.30 mol % or less, The A is at least one element from Groups 12, 13, 14, 15, and 16.

13. The conductive film according to claim 12, wherein The M is Ti, and the A is Al.

14. A slurry, wherein The particulate material as a raw material for the conductive film according to any one of claims 7 to 13 is contained in a liquid medium.

15. A method for producing a conductive film, wherein: include: (a) applying the slurry according to claim 14 to a substrate to form a precursor of the conductive film containing particles of the layered material, and (b) drying the precursor.

16. The method for producing a conductive film according to claim 15, wherein: The applying of the slurry in (a) is performed by spraying, spin coating or doctor blade method.

17. The method for producing a conductive film according to claim 15 or 16, wherein: The above steps (a) and (b) are repeated a total of two or more times.

18. The method for producing a conductive film according to claim 15 or 16, wherein: The conductive film according to any one of claims 1 to 6 can be obtained.

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