KR102453099B1 - 2d nanosheet and method for manufacturing thereof - Google Patents

Abstract

The present invention provides a method for manufacturing a two-dimensional nanosheet, comprising: preparing a three-dimensional bulk material powder, injecting nitrogen to form a nitrogen atmosphere; mixing a first cation precursor solution into the three-dimensional bulk material powder; intercalating the first cations between the layers of the three-dimensional bulk material having a multilayer structure by treating the mixture with a first sonication; ion-exchanging the first cation intercalated between the layers of the three-dimensional bulk material with a second cation by incorporating a second cation precursor solution; And exfoliating the two-dimensional nanosheet by second sonic treatment of the mixture containing the second cation precursor; It relates to the preparation of an ink composition comprising.

Description

Two-dimensional nanosheet and manufacturing method thereof

The present invention relates to a method for manufacturing a nanosheet of a peeled two-dimensional material, a two-dimensional nanosheet prepared by the method, and an ink composition including the two-dimensional nanosheet, and a method for manufacturing the same.

This research was made with the support of the Korea Energy Research Institute R&D project (C0-2417) and the Korea Forest Service (Korea Forestry Promotion Agency) forest science and technology R&D project (2020229B10-2022-AC01).

Recently, various two-dimensional materials such as MoS ₂ , WS ₂ , and WSe ₂ are attracting attention as future semiconductor materials. The above two-dimensional structural materials are flexible and strong with a thin nanometer thickness, and they have various properties such as metallic, semiconductor, and non-conductive properties, so they can be used in various fields such as electronic devices, sensors, and energy. In particular, in the case of a two-dimensional heterogeneous multi-layer material, there is an advantage in that physical properties can be modulated according to the stacking combination of a single layer, and a synergistic coupling between the two-dimensional material properties can be realized. For example, in the case of a graphene/MoS ₂ heterogeneous stacked material, it has been reported that the charge accumulation is increased by about 10 times or more due to the intercalation reaction compared to the MoS ₂ /MoS ₂ homogeneous stacked material (Reference, P. Kim). et al., Nature 558, 425 (2018)). In addition, it has been observed that the 1.3 nm thick ultra-thin graphene/MoS ₂ heterogeneous stacked (graphene/MoS ₂ /graphene) material exhibits 7 times higher photocurrent than the MoS ₂ single stacked material (Reference, Nat. Commun). 7, 13278 (2016)).

Two-dimensional transition metal dichalcogenide (TMD) materials and heterogeneous multi-layered two-dimensional materials are expected to have high potential for adoption in various high value-added applications such as electronics, optoelectronics, energy, sensors, and biomedicine in the future. The global market for 2D materials is expected to increase more than 23 times from $5.5 million in 2020 to about $130 million in 2030. In addition, the total domestic market size in 2030 is expected to be 17.8 million dollars, and the compound annual growth rate (CAGR) between 2020 and 2030 is expected to be 36.72%.

In addition, two-dimensional transition metal dichalcogenide materials and heterogeneous multi-layered two-dimensional materials have infinite possibilities not only in the market of the material itself but also in its application fields, especially in the energy field such as secondary batteries and thermoelectric devices, with high efficiency and low power It has very high potential for application to device and material development.

Among various application fields, the lithium ion battery market among secondary batteries is growing in size every year. Many things related to our daily life are done through electronic devices, and electronic devices are becoming indispensable in our daily life. In addition, the demand for batteries, which are essential elements constituting electronic devices, is increasing, and the importance of developing better batteries is increasing. In the future, batteries will be used in more places than they are now, and batteries with higher capacity and higher efficiency will be required. Batteries play a pivotal role not only in mobile electronic devices but also in the electric vehicle market, and as the demand for eco-friendly vehicles grows, the global automobile market is currently trying to change from fossil fuel-powered vehicles to electric vehicles. We are focusing on increasing the mileage.

In addition, as lithium-ion batteries are expected to be used as secondary batteries for electric vehicles in the future, the development of new high-capacity materials capable of fast charging is essential in order to satisfy long-distance driving and consumer convenience. In the charging and discharging of a lithium-ion battery, when the battery is being charged, lithium ions and electrons from the positive electrode enter the negative electrode, and when the battery is discharged, lithium ions and electrons from the negative electrode move to the positive electrode. At this time, how fast the negative electrode can receive lithium ions is a key factor in determining the charging speed of a lithium ion battery, which is greatly affected by the composition of the negative electrode material and the characteristics of the electrode structure.

Graphite, the most used anode material, has advantages of low cost and excellent structural stability, but its low capacity (theoretical capacity: 372 mAh g ^-1 ) is not sufficient to extend the mileage of electric vehicles or the use time of mobile phones and electronic devices. The downside is that it isn't enough. In addition, there is a disadvantage in that the possibility of exposure to deterioration due to lithium precipitation in the graphite anode during rapid charging is very high. Recently, silicon oxide-based (SiOx) anode materials are aiming for their place due to their high specific capacity, but the material has a large volume expansion during the cycle process, which causes the electrode structure to be rapidly destroyed and thus has a disadvantage that the lifespan is not long. Two-dimensional materials, known as transition metal dichalcogenide materials, have attracted considerable interest in many research fields because they have unique electrical, mechanical, and optical properties. . However, due to poor conductivity, it is necessary to secure conductivity in order to secure electrode capacity, and it is also necessary to solve the problem of volume expansion due to insertion/desorption of electrolyte ions. Unlike graphite, a two-dimensional heterogeneous multilayer material can control the interlayer distance, so if graphite and a heterogeneous multilayer material are properly mixed, it is possible to realize a material with high capacity characteristics and excellent structural stability, as well as smoothly receive lithium ions during rapid charging. expect to be able to take it.

For the production of the two-dimensional transition metal dichalcogenide nanosheet, a two-dimensional nanosheet is synthesized using a bottom-up synthesis method such as a chemical vapor deposition method or a sol-gel synthesis method so far, or a bulk two-dimensional material is mechanically or chemically synthesized. A method of manufacturing a two-dimensional nanosheet using a top-down synthesis method such as exfoliation is widely used. A representative method of the mechanical peeling method is the 'Scotch tape' method, which can secure high-quality materials, but has the disadvantage of producing only a small amount of output. In the case of chemical vapor deposition, the control ability of the material layer and the microstructure of the substrate is excellent, but it is difficult to separate the substrate and the two-dimensional material, and most of the processes are complicated due to high temperature and high vacuum synthesis conditions, and mass production is difficult. . In addition, the sol-gel synthesis method is a commonly used method, but a large amount of elements are consumed to obtain a small amount of result, and there is a problem of performance degradation due to the formation of unwanted surface groups such as hydroxyl groups and byproducts such as pore formation. . The chemical peeling method is a method of selectively inserting positive and negative ions between two-dimensional material layers to separate them. Compared to methods such as mechanical peeling, chemical vapor deposition, and sol-gel, it is possible to scale-up and the process is relatively simple, but the production and yield It is still at a very low level for commercialization.

The above-mentioned two-dimensional heterogeneous multi-layer material refers to a nanocomposite material made by a combination of different kinds of two-dimensional materials, and after exfoliating the two-dimensional material in nanosheet units, different kinds of two-dimensional exfoliating materials are alternately used A two-dimensional heterogeneous multi-layer material is manufactured by making it a composite material by laminating it. Currently, there is a demand for scale-up manufacturing of these exfoliated two-dimensional nanosheet materials and development of a process for improving yield. In addition, since the two-dimensional nanosheet material is well dispersed and the dispersed state is maintained for a long period of time, there is also a need for an easy-to-storage ink and ink manufacturing method.

The present invention has been devised to solve the above-described problem, and an aspect of the present invention provides a method for manufacturing a two-dimensional nanosheet.

Another embodiment of the present invention provides a two-dimensional nanosheet manufactured by the above manufacturing method.

Another embodiment of the present invention provides a method for preparing a two-dimensional nanosheet ink composition.

Another embodiment of the present invention provides a two-dimensional nanosheet ink composition prepared by the above manufacturing method.

However, the technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned are clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. it could be

As a technical means for achieving the above-described technical problem, one aspect of the present invention is,

A method of manufacturing a two-dimensional nanosheet, comprising: preparing a three-dimensional bulk material powder, and injecting nitrogen to form a nitrogen atmosphere; mixing a first cation precursor solution into the three-dimensional bulk material powder; intercalating the first cations between the layers of the three-dimensional bulk material having a multilayer structure by treating the mixture with a first sonication; ion-exchanging the first cation intercalated between the layers of the three-dimensional bulk material with a second cation by incorporating a second cation precursor solution; and exfoliating the two-dimensional nanosheet by second sonic treatment of the mixture including the second cation precursor.

The two-dimensional nanosheet may be characterized in that it is a transition metal dichalcogenide, or graphene.

The two-dimensional nanosheet may be at least one selected from MoSe ₂ , MoS ₂ , WS ₂ , WSe ₂ , TiS ₂ , TiSe ₂ , ReS ₂ , ZrTe ₂ , and NbSe ₂ .

The first cation may be an alkali metal cation.

The second cation may be one type of cation selected from the group consisting of ammonium, hydrocarbon-substituted primary to tertiary ammonium, magnesium, zinc (Zn) and hydronium (H ₃ O ⁺ ). have.

The first sonic treatment may be performed for 0.5 to 10 hours, and the second sonic treatment may be performed for 0.1 to 5 hours.

It may be characterized in that the stirring proceeds simultaneously with the first or second sound wave treatment.

The stirring may be performed multiple times during the first or second sonic treatment, and may be characterized in that it proceeds for 0.1 to 2 hours per one time.

passing the solution obtained in the step of peeling the two-dimensional nanosheet through a predetermined filter, and washing the peeled two-dimensional nanosheet powder with a solvent; It may be characterized in that it further comprises the step of drying the obtained powder.

The two-dimensional nanosheet may be characterized in that it includes one to three layers.

In addition, another aspect of the present invention,

Provided is a two-dimensional nanosheet manufactured according to the manufacturing method.

In addition, another aspect of the present invention,

preparing a two-dimensional nanosheet material according to the manufacturing method; mixing the two-dimensional nanosheet material and a solvent; sonicating the mixture of the two-dimensional nanosheet material and the solvent; and obtaining a two-dimensional nanosheet ink composition by separating the supernatant of the separated mixture.

In addition, another aspect of the present invention,

It provides a two-dimensional nanosheet ink composition prepared according to the above manufacturing method.

According to one aspect of the present invention, it is possible to provide an economical peeling method in terms of energy while being able to scale-up the two-dimensional nanosheet material.

In addition, according to one aspect of the present invention, the two-dimensional nanosheet material is well dispersed, the dispersed state is maintained for a long time, and thus it is possible to provide a two-dimensional nanosheet ink composition and a method for manufacturing the same, which is easy to store for a long time. .

The effects of the present invention are not limited to the above effects, and it should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 schematically shows a method for manufacturing a two-dimensional nanosheet according to an embodiment of the present invention.
Figure 2a is a flowchart showing a method of manufacturing a two-dimensional nanosheet ink composition according to an embodiment of the present application.
Figure 2b is a high-concentration and low-concentration ink photograph of the two-dimensional nanosheet ink composition according to an embodiment of the present application.
Figure 3 shows XRD data comparing the two-dimensional _two -dimensional nanosheet MoS prepared according to an embodiment of the present application with a bulk material.
FIG. 4 shows XRD data comparing the two-dimensional _two -dimensional MoSe nanosheets prepared according to an embodiment of the present application to a bulk material.
Figure 5a is an SEM image of the bulk material of the MoS _two -dimensional nanosheet prepared in accordance with an embodiment of the present application, respectively 30000 times and shows 50000 times the images.
Figure 5b shows a TEM image of the exfoliated material of the MoS _two -dimensional nanosheet prepared according to an embodiment of the present application.
6 is an SEM image of the bulk material before exfoliation of the two-dimensional _two -dimensional MoSe nanosheet prepared according to an embodiment of the present application, showing images of 3000 times and 10000 times, respectively.
7 shows a TEM image of the exfoliated material of the MoSe _two -dimensional nanosheet prepared according to an embodiment of the present application.
8 is an SEM image of the bulk material before exfoliation of the WS _two -dimensional nanosheet prepared according to an embodiment of the present application, and shows images of 1000 times and 3000 times, respectively.
9 shows a TEM image of the exfoliated material of the WS _two -dimensional nanosheet prepared according to an embodiment of the present application.
FIG. 10 is XRD data for an analysis of exfoliation efficiency according to whether sonic treatment is performed during a cation insertion process in a method for manufacturing a two-dimensional nanosheet according to an embodiment of the present application.
11 is XRD data for the analysis of exfoliation efficiency according to whether stirring, in addition to sonic treatment in the ion-exchange process in the method for manufacturing a two-dimensional nanosheet according to an embodiment of the present application.

Hereinafter, the present invention will be described in more detail. However, the present invention may be embodied in various different forms, and the present invention is not limited by the embodiments described herein, and the present invention is only defined by the claims to be described later.

In addition, the terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the entire specification of the present invention, 'including' any component means that other components may be further included, rather than excluding other components, unless otherwise stated.

The first aspect of the present application is

A method of manufacturing a two-dimensional nanosheet, comprising: preparing a three-dimensional bulk material powder, and injecting nitrogen to form a nitrogen atmosphere; mixing a first cation precursor solution into the three-dimensional bulk material powder; intercalating the first cations between the layers of the three-dimensional bulk material having a multilayer structure by treating the mixture with a first sonication; ion-exchanging the first cation intercalated between the layers of the three-dimensional bulk material with a second cation by incorporating a second cation precursor solution; and exfoliating the two-dimensional nanosheet by second sonic treatment of the mixture including the second cation precursor.

Hereinafter, a method for manufacturing a two-dimensional nanosheet according to the first aspect of the present application will be described in detail.

First, in one embodiment of the present application, preparing a three-dimensional bulk material powder, and injecting nitrogen to form a nitrogen atmosphere; includes.

In one embodiment of the present application, the three-dimensional bulk material powder may be a bulk material of transition metal dichalcogenide, or a three-dimensional bulk material such as graphite. The product of the present invention may be a two-dimensional nanosheet material having a layered structure in which bulk transition metal dichalcogenide is peeled off in a single layer or in multiple layers.

The transition metal atoms and chalcogen atoms constituting the transition metal dichalcogenide exist in the form of covalent bonds and are connected by a weak Van der Walls (VdW) interaction between the layers, so that physical and chemical exfoliation can occur. It is possible.

Conventionally, the peeling of the two-dimensional nanosheets was physically removed using a scotch tape, peeling through a ball mill, or a method of performing a peeling process in an appropriate solvent. Since the above-described methods have poor peeling efficiency or are uneconomical in terms of energy, an improved peeling process is required, leading to the present invention.

In one embodiment of the present application, the transition metal dichalcogenide may be represented by MX ₂ , where M is a transition metal, X is a chalcogen element, and M is Mo, W, Nb, and Ti, etc. One selected from the group consisting of transition metals, wherein X may be one selected from the group consisting of S, Se and Te, preferably MoSe ₂ , MoS ₂ , WS ₂ , WSe ₂ , TiS ₂ , TiSe ₂ , ReS ₂ , ZrTe ₂ , NbSe ₂ It may be at least one selected from, more preferably MoS ₂ , MoSe ₂ , WS ₂ or NbSe ₂ It may be.

Next, in one embodiment of the present application, mixing and mixing the first cation precursor solution in the three-dimensional bulk material powder; includes.

In one embodiment of the present application, the first cation is not particularly limited as long as it is a cation that can be inserted into the layered structure of the three-dimensional bulk material, but may preferably be an alkali metal cation, and more preferably an ion size It may be a lithium cation (Li ⁺ ), which may be small and easy to insert.

In one embodiment of the present application, the first cation precursor solution may be a metal element or an organo-alkali compound, preferably butyllithium, sodium naphthalenide, and more preferably n-butyllithium. have.

Next, in one embodiment of the present application, the mixture is subjected to a first sonication treatment to intercalate the first cations between the layers of the three-dimensional bulk material having a multi-layer structure.

The above-described step may be for facilitating intercalation of the first cations into the multi-layered structure of the three-dimensional bulk material through sonication.

In one embodiment of the present application, the first sound wave treatment may be performed for 0.5 to 10 hours, preferably 1 to 6 hours, more preferably 1 to 3 hours. If the first sonic treatment is made for less than 0.5 hours, the first cations may not be sufficiently inserted into the multilayered layered structure, and if it is made for more than 10 hours, it may be uneconomical or decomposition of the material may occur.

Next, in one embodiment of the present application, the step of ion-exchanging the first cation inserted between the layers of the three-dimensional bulk material with the second cation by incorporating a second cation precursor solution.

When the first cation is intercalated with the three-dimensional bulk material and the interlayer spacing is increased, the interlayer bonding force is weakened. It may refer to a process of ion-exchanging an intercalated first cation (eg, an alkali metal cation) with a second cation. For example, when lithium ions are ion-exchanged with ammonium ions (NH ₄ ⁺ ) and washed with distilled water in a subsequent step, the second cations (eg, NH ₄ ⁺ ) between the layers are exchanged with H+, so that the bulk three-dimensional layered material is easily formed. It is possible to exfoliate from a single layer to a small number of multilayer two-dimensional nanosheet materials.

In one embodiment of the present application, the second cation may include a cation having an ionic size larger than that of the first cation, and as a non-limiting example, ammonium, primary to tertiary ammonium substituted with hydrocarbon, magnesium, zinc (Zn ) and hydronium (H ₃ O ⁺ ) may be one kind of cation selected from the group consisting of, preferably ammonium ion.

Finally, in one embodiment of the present application, the second sonic treatment of the mixture containing the second cation precursor to peel the two-dimensional nanosheet; includes.

The above-described step may be to promote intercalation of the second cation with the first cation through sonic treatment in the multi-layered structure of the three-dimensional bulk material.

In one embodiment of the present application, the second sound wave treatment may be performed for 0.1 to 5 hours, preferably 0.2 to 4 hours, more preferably 0.5 to 3 hours. If the second sonic treatment is made for less than 0.1 hour, the first cation may not be sufficiently inserted into the multilayered layered structure, and if it is made for more than 5 hours, it may be uneconomical or decomposition of the material may occur.

In one embodiment of the present application, it may be characterized in that the stirring proceeds simultaneously with the first or second sound wave treatment. By simultaneously proceeding with the stirring process, the intercalation of the first cation between the layers of the three-dimensional layered bulk material, or the ion-exchange with the second cation and the intercalation of the three-dimensional layered bulk material between the layers can be further promoted, and a simple The addition of the process can shorten the overall process time. The stirring may be carried out for 0.1 to 5 hours, preferably 0.2 to 4 hours, more preferably 0.5 to 3 hours. In addition, in one embodiment of the present invention, stirring may be continuously performed simultaneously during the first or second sonication step, but may be performed multiple times, and decomposition after exfoliation of the two-dimensional nanosheet material In terms of prevention, it may be carried out for 0.1 to 2 hours per time, preferably 0.2 to 1 hour per time. Equipment required for the stirring process is not limited as long as it is used in the art.

In one embodiment of the present application, passing the solution obtained in the step of peeling the two-dimensional nanosheet through a predetermined filter, washing the two-dimensional nanosheet powder exfoliated with a solvent; It may be characterized in that it further comprises the step of drying the obtained powder. As the second cations between the layers of the three-dimensional layered bulk material are exchanged with H+ in the above-described step, the bulk three-dimensional layered material can be easily exfoliated into a single layer or a small number of multi-layered two-dimensional nanosheet materials. Thereafter, the solid phase may be filtered through a filter and dried to obtain an exfoliated two-dimensional nanosheet powder. The type of washing solution used in this step is not limited, but distilled water, ultrapure water, etc. may be used. In addition, in the drying step, the drying temperature and time may be appropriately adjusted to obtain a two-dimensional nanosheet powder.

The second aspect of the present application is

It provides a two-dimensional nanosheet prepared according to the manufacturing method of the first aspect of the present application.

Although detailed descriptions of parts overlapping with the first aspect of the present application are omitted, the contents described with respect to the first aspect of the present application may be equally applied even if the description thereof is omitted in the second aspect.

In one embodiment of the present application, the two-dimensional nanosheet may be characterized in that it comprises 1 to 20, preferably 1 to 10, more preferably 1 to 3 layers. Since exfoliated two-dimensional nanosheets can be obtained with high efficiency by the method according to the first aspect of the present application, it can be expected that the ratio of the monolayer is high.

The third aspect of the present application is

preparing a two-dimensional nanosheet material according to the manufacturing method; mixing the two-dimensional nanosheet material and a solvent; sonicating the mixture of the two-dimensional nanosheet material and the solvent; and obtaining a two-dimensional nanosheet ink composition by separating the supernatant of the separated mixture.

Although detailed descriptions of parts overlapping with the first and second aspects of the present application are omitted, the descriptions of the first and second aspects of the present application may be equally applied even if the description is omitted in the third aspect. .

Hereinafter, a method for producing a two-dimensional nanosheet ink composition according to the third aspect of the present application will be described in detail.

Figure 2a is a flowchart showing a method of manufacturing a two-dimensional nanosheet ink composition, according to an embodiment of the present application.

First, in one embodiment of the present application, after preparing a two-dimensional nanosheet material according to the manufacturing method, mixing the two-dimensional nanosheet material and a solvent; includes. In the above step, it is preferable to immediately use the 2D nanosheet material produced after filtering and washing the 2D nanosheet material prepared according to the first aspect of the present application, and the dried powder may be redispersed and used. something to do.

In one embodiment of the present application, the solvent for dispersing the two-dimensional nanosheet material is not particularly limited to an organic solvent or an inorganic solvent, but preferably distilled water, alcohol (eg, ethanol), and combinations thereof. .

Next, in one embodiment of the present application, sonic treatment of the mixture of the two-dimensional nanosheet material and the solvent; includes.

In one embodiment of the present application, the sonic treatment may be performed for 0.1 to 5 hours, preferably 0.3 to 4 hours, more preferably 0.5 to 3 hours. If the sonic treatment is made for less than 0.1 hours, the two-dimensional nanosheet material may not be sufficiently dispersed, and if it is made for more than 5 hours, it may be uneconomical.

In one embodiment of the present application, after performing the sonication treatment, the step of phase-separating the suspension may be further included. In this step, as to allow the undispersed two-dimensional nanosheet material to be precipitated, a method of precipitation separation for a certain period of time in a normal pressure/room temperature process can be used. In this case, there is no limitation on the period as long as the precipitation can be sufficiently performed, but the precipitation separation may be performed for a period of preferably 1 to 5 days, more preferably about 3 days. In addition, in addition to the precipitation separation in the above-described normal pressure / room temperature process, the suspension may be phase-separated using centrifugation or phase-separated by various methods in the art for phase separation.

Next, in one embodiment of the present application, separating the supernatant of the separated mixture to obtain a two-dimensional nanosheet ink composition; includes.

In one embodiment of the present application, the separation may be performed by various conventional methods, but preferably by centrifugation.

In the case of the two-dimensional nanosheet ink composition obtained by the above method, the two-dimensional nanosheet material can be maintained in a dispersed state without agglomeration or re-lamination for a long period of time, and the dispersed state can be maintained even for a time period of about 1 month or more. These properties mean that it is possible to provide a method for long-term storage of exfoliated two-dimensional nanosheets.

The fourth aspect of the present application is

It provides a two-dimensional nanosheet ink composition prepared according to the above manufacturing method.

Although detailed descriptions of parts overlapping with the first to third aspects of the present application are omitted, the descriptions of the first to third aspects of the present application may be equally applied even if the description is omitted in the fourth aspect. .

In one embodiment of the present application, since the two-dimensional nanosheet and the composition including the same have a layered porous property, in addition to the electrode active material of a supercapacitor or a secondary battery, a catalyst for water purification, an anticancer agent, an immunodeficiency virus therapeutic agent, mold and bacteria As it can be applied in various fields such as an infection treatment agent, an antimalarial agent, various drug delivery materials, photocatalysts, sensors, and aerospace materials, it can be used as a commercially very useful material.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

Example 1: Preparation of exfoliated two-dimensional transition metal dichalcogenide nanosheet material

1 schematically illustrates a method for manufacturing a two-dimensional nanosheet, according to an embodiment of the present invention.

Transition metal dichalcogenide (MoS ₂ , MoSe ₂ and WS ₂ , etc.) bulk powder 10g was put into an Erlenmeyer flask, sealed, and nitrogen replacement was performed for at least 10 minutes to create a nitrogen environment inside the flask. After that, 80 mL of n-butyllithium solution (2.5 M solution in hexane, Acros Organics) was added through a syringe (8 mL per 1 g of transition metal dichalcogenide bulk powder) and sonicated (sonicated) for 3 hours. , The transition metal dichalcogenide bulk powder reacted with n-butyllithium solution to allow Li ⁺ to be evenly inserted between the transition metal dichalcogenide layers. After sonic treatment, 700 mL of supersaturated NH ₄ Cl aqueous solution (70 mL of supersaturated NH ₄ Cl aqueous solution per 1 g of transition metal dichalcogenide powder) is added through a syringe to convert Li ⁺ inserted between the transition metal dichalcogenide layers to NH ₄ ⁺ and ion exchange to weaken the interlayer bonding force of the transition metal dichalcogenide material. The amount of sample required can be adjusted according to the amount of transition metal dichalcogenide powder to be peeled off. Thereafter, the transition metal dichalcogenide material with weakened interlayer bonding strength was exfoliated by sonication or stirring. At this time, when sonic treatment (about 3 hours) was performed, it had the effect of shortening the peeling time compared to the case of stirring (about 12 to 24 hours). Not only could it be possible, but it was possible to improve the peeling yield. After all the exfoliation was performed, a transition metal dichalcogenide powder exfoliated through filtration was obtained. In this process, the exfoliated transition metal dichalcogenide powder was washed with distilled water and ethanol. After all washing was completed, the obtained powder was dried at 80° C. for more than 12 hours.

Example 2: Preparation of exfoliated two-dimensional transition metal dichalcogenide nanosheet ink composition

A method for preparing the ink composition of the exfoliated transition metal dichalcogenide two-dimensional nanosheet is as shown in FIG. 2A .

The exfoliated two-dimensional nanosheet material was placed in a vial without a drying process after filtration and washing under reduced pressure. Then, it was filled with distilled water and ethanol and sonicated for 1 hour. After separation of the precipitation so that the powder not dispersed for 3 days can be precipitated, the supernatant was transferred to another container. An example of the prepared exfoliated transition metal dichalcogenide ink is shown in FIG. 2B.

Referring to FIG. 2B , it can be confirmed that the ink composition of the two-dimensional nanosheet obtained by separating only the supernatant can be stored for a long time without restacking or agglomeration of the two-dimensional nanosheet materials. In fact, it could be confirmed that the dispersed state was maintained despite the period of more than one month. The above results are interpreted as suggesting the possibility of long-term storage of the scale-up produced 2D nanosheet material depending on the field of application.

Example 3-1: Characterization of exfoliated two-dimensional transition metal dichalcogenide nanosheet material

Analysis of the exfoliated two-dimensional transition metal dichalcogenide nanosheet material was performed using X-ray diffraction (XRD, Example 3-1), and a scanning electron microscope (SEM) and transmission electron microscope (TEM) of Example 3-2 did.

Bulk MoS ₂ and exfoliated MoS ₂ samples were mixed with Al ₂ O ₃ standard samples at a weight ratio of 1:1 to measure X-ray diffraction (XRD) data, and Rietveld analysis was performed. As a result of Rietveld analysis, no other peaks were observed other than hexagonal MoS ₂ and standard sample Al ₂ O ₃ in both samples before and after exfoliation, and the intensity of the MoS ₂ peak decreased after exfoliation and full width half maximum (FWHM). ) was confirmed to increase. MoS ₂ and Al ₂ O ₃ The degree of exfoliation was measured from the change in the ratio of the MoS ₂ (002) peak and Al ₂ O ₃ (104) peak, which have the highest intensity among the peaks of the X-ray diffraction data. As shown in FIG. 3 , the MoS ₂ (002) peak is indicated by using a “#” symbol, and the Al ₂ O ₃ (104) peak is indicated by using a “*” symbol. MoS ₂ MoS ₂ (002) peak to Al ₂ O ₃ (104) peak intensity ratio before exfoliation was 9.05, and MoS ₂ after exfoliation was 1.25. From this peak ratio, the degree of exfoliation compared to MoS ₂ bulk raw material was 1-(1.25/9.05)=86.2%. By multiplying the yield of the sample calculated in the delamination process, the delamination yield of the MoS ₂ sample can be calculated.

In the case of MoSe ₂ sample, after mixing with Al ₂ O ₃ in the same manner as MoS ₂ , X-ray diffraction results were measured and Rietveld analysis was performed. MoSe ₂ has the same crystal structure as MoS ₂ , so the degree of exfoliation was analyzed in the same way as MoS ₂ . As shown in FIG. 4 , the MoSe ₂ (002) peak is indicated by a “#” symbol, and the Al ₂ O ₃ (104) peak is indicated by a “*” symbol. The degree of exfoliation was measured from changes in the ratio of MoSe ₂ (002) peak and Al ₂ O ₃ (104) peak, which have the highest intensity among the X-ray diffraction data peaks of MoSe ₂ and Al ₂ O ₃ . The ratio of the Al ₂ O ₃ (104) peak to the MoSe ₂ (002) peak before MoSe ₂ exfoliation was 15.57, and 1.57 after MoSe 2 exfoliation. From this ratio, it was confirmed that the degree of exfoliation compared to the bulk raw material of MoSe ₂ was 1-(1.57/15.57)=89.9%. By multiplying the yield of the sample calculated in the exfoliation process, the exfoliation yield of the MoSe ₂ sample can be calculated. As a result of the analysis, it was confirmed that the exfoliated MoS ₂ and MoSe ₂ materials of the present invention exhibited a degree of exfoliation of 85% or more.

Example 3-2: SEM, TEM analysis of bulk/exfoliated two-dimensional transition metal dichalcogenide nanosheet material

The images of the material before and after exfoliation were analyzed using a scanning electron microscope (SEM) for bulk MoS ₂ powder and a transmission electron microscope (TEM) for exfoliated MoS ₂ , respectively. Compared to the bulk MoS ₂ shown in Fig. 5a, in the case of the exfoliated MoS ₂ shown in Fig. 5b, it was confirmed that the exfoliation was good with a thin layer. In addition, it was confirmed that the crystallinity was well maintained during high-resolution TEM (HR-TEM) measurement and matched well with the hexagonal MoS ₂ structure through FFT analysis.

MoSe ₂ , WS ₂ prepared in the same manner as in the embodiment of the present invention was similarly exfoliated and analyzed, and the contents are as follows. 6 is an SEM image before MoSe ₂ exfoliation, which is 3000 times and 10000 times images, respectively. Through this, it can be confirmed that nanosheets of various sizes are agglomerated.

On the other hand, as shown in FIG. 7 , when looking at the TEM photograph after exfoliation, it was confirmed that the thin layer of MoSe ₂ was exfoliated _. could check In addition, through FFT pattern analysis, it was found that the structure matched well with the MoSe ₂ structure. Through this, it was confirmed that the exfoliation process of the present invention can be well applied not only to MoS ₂ but also to other transition metal dichalcogenide materials such as MoSe ₂ .

As shown in FIG. 8, the SEM photograph before WS ₂ peeling also confirmed that many nanosheets were agglomerated before peeling, but looking at the TEM photograph after peeling (FIG. 9), the peeled WS ₂ nanosheets could be confirmed. Even in the case of exfoliated WS ₂ , it was confirmed that the crystallinity was well maintained through HR-TEM and matched well with the WS ₂ structure through FFT pattern analysis.

Through the above results, it was confirmed that in the case of the two-dimensional nanosheet manufacturing method of the present invention, it can be utilized with high efficiency in various transition metal dichalcogenide materials (in addition, two-dimensional nanosheet materials including graphene) did.

Example 4-1: Analysis of exfoliation efficiency according to the presence or absence of sonication in the cation insertion process

This experimental example was conducted to demonstrate the effect of the first sonic treatment on the exfoliation efficiency when n-BuLi was added and then dispersed using ultrasonic waves. To proceed with the experiment, a sample in which sonic treatment was not performed after addition of n-BuLi and the subsequent procedure was the same was used as a comparative example. The XRD peak is shown in FIG. 10 .

In the case of the comparative example, although the (002) peak in the interlayer direction became broad compared to the bulk material, it was confirmed that the peak intensity was still higher than that of the example in which the first ultrasonic treatment was performed. The exact values are (002):(100) = 5.19:1 for the bulk sample, 3.95:1 for the sample without primary sonication, and 1.28:1 for the sample with sonication, where the intensity of (002) is greatly reduced. could confirm that

In addition, the higher the degree of peeling (the better the peeling efficiency), the wider the interlayer spacing and the peak position is down-shifted. , it was confirmed that the peak shifting occurred with 2 theta = 14.08 (d = 0.6283 nm) for the sample that was not subjected to the primary sonication treatment, and 2 theta = 13.87 (d = 0.6375 nm) for the sample that was subjected to the sonication treatment. In terms of spacing, it was found that the sample with sonic treatment and the sample without treatment showed a difference of about 0.0092 nm. Therefore, it could be confirmed that the first sonic treatment of the present invention is an essential process for excellent exfoliation efficiency.

Example 4-2: Analysis of peeling efficiency according to whether stirring, in addition to sonication in the ion-exchange process

This experimental example was conducted to confirm whether the exfoliation efficiency was improved when the stirring was further carried out at the same time when the dispersion was carried out through the second sonic treatment after ion-exchange with ammonium ions. For the experiment, a sample including only the second sonication treatment, a sample in which agitation was performed simultaneously with the second sonication treatment, and a bulk material sample were used. 11 shows the XRD peak.

As the degree of delamination increases, the peak intensity of (002) in the inter-layer direction tends to be lower and broad. Referring to FIG. 11 , when comparing the results of sonic treatment alone and stirring and sonication at the time of NH ₄ Cl injection, it can be observed that the latter exfoliation occurs better, and the relative peaks of (002): (100) The strength of the bulk sample was (002):(100)= 5.19:1, when only sonic treatment was performed, 2.51:1, and when stirring and sonic treatment were performed together, it was confirmed that the strength was significantly reduced to 1.28:1.

In addition, the higher the degree of delamination, the wider the interlayer spacing and the lower the peak position. In the case of bulk material, (002) peak position was 2theta=14.36 (d = 0.6286 nm), and when only sonication was performed, (002) peak was 2theta= 13.94 (d = 0.6345 nm), and when stirring and sonication were performed together, it was confirmed that a fine but peak shifting occurred as 2theta=13.87 (d = 0.6375 nm), and d-spacing after the first sonication was about It can be seen that there is a difference of about 0.003 nm.

Therefore, it was confirmed that the peeling efficiency can be further improved when stirring is performed simultaneously in the second sonic treatment process of the present invention.

Claims (13)

As a method of manufacturing a two-dimensional nanosheet,
preparing a three-dimensional bulk material powder, and injecting nitrogen to form a nitrogen atmosphere;
mixing a first cation precursor solution into the three-dimensional bulk material powder;
intercalating the first cations between the layers of the three-dimensional bulk material having a multilayer structure by treating the mixture with a first sonication;
ion-exchanging the first cation intercalated between the layers of the three-dimensional bulk material with a second cation by incorporating a second cation precursor solution;
exfoliating the two-dimensional nanosheet by subjecting the mixture including the second cation precursor to a second sonic treatment;
passing the solution obtained in the step of peeling the two-dimensional nanosheet through a predetermined filter, and washing the peeled two-dimensional nanosheet powder with a solvent; and
Drying the obtained powder; comprising, a method for producing a two-dimensional nanosheet.
The method of claim 1, wherein the two-dimensional nanosheet is a transition metal dichalcogenide, or graphene.
According to claim 1, wherein the two-dimensional nanosheet MoSe ₂ , MoS ₂ , WS ₂ , WSe ₂ , TiS ₂ , TiSe ₂ , ReS ₂ , ZrTe ₂ , NbSe ₂ Characterized in that at least one selected from 2, 2 Method for manufacturing dimensional nanosheets.
The method of claim 1, wherein the first cation is an alkali metal cation.
According to claim 1, wherein the second cation is ammonium, a hydrocarbon-substituted primary to tertiary ammonium, magnesium, zinc (Zn), and hydronium (H ₃ O ⁺ ) One kind of cation selected from the group consisting of A method of manufacturing a two-dimensional nanosheet, characterized in that.
The method of claim 1, wherein the first sonic treatment is performed for 0.5 to 10 hours, and the second sonic treatment is performed for 0.1 to 5 hours.
According to claim 1, characterized in that the stirring proceeds at the same time as the first or second sonic treatment, the two-dimensional nanosheet manufacturing method.
◈Claim 8 was abandoned when paying the registration fee.◈ The method of claim 7 , wherein the stirring is performed multiple times during the first or second sonication treatment, and is performed for 0.1 to 2 hours per one time.
delete ◈Claim 10 was abandoned when paying the registration fee.◈ The method of claim 1, wherein the two-dimensional nanosheet comprises 1 to 10 layers.
A two-dimensional nanosheet manufactured according to the manufacturing method according to claim 1 .
Preparing a two-dimensional nanosheet material according to the manufacturing method according to claim 1;
mixing the two-dimensional nanosheet material and a solvent;
sonicating the mixture of the two-dimensional nanosheet material and the solvent; and
Separating the supernatant of the separated mixture to obtain a two-dimensional nanosheet ink composition; comprising, a method for producing a two-dimensional nanosheet ink composition.
A two-dimensional nanosheet ink composition prepared according to the method according to claim 12 .

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