Two-dimensional material capable of being self-stripped in solvent and prepared on large scale

Abstract

The invention discloses a one-dimensional amorphous crystal, and provides a method for preparing a high-quality two-dimensional material on a large scale at low cost. The one-dimensional amorphous crystal can be self-stripped in a solvent to form a highly uniform two-dimensional material suspension. The preparation method of the two-dimensional material is very simple in process, high in speed and low in cost, water can be used as a solvent, and the two-dimensional material is environment-friendly and easy to amplify for large-scale preparation; the obtained two-dimensional material has very high quality, few defects and good monolayer property, has a transverse size capable of reaching a millimeter level, and has a wide potential application prospect, for example, the two-dimensional material can be used as a template material for preparing a nano material surface mask, or can be used as a micro-catalytic container, a catalyst precursor, a drug carrier, a coating additive and an electronic sensing device.

Description

Technical Field

[0001] The present invention relates to the technical field of two-dimensional material preparation, and particularly to a method for preparing two-dimensional materials by self-exfoliation of one-dimensional amorphous crystals in a solvent. Such materials can undergo self-exfoliation in a solvent to form a two-dimensional material suspension with high quality and high monolayer property. The preparation process is extremely simple, with extremely low cost, and is easy to scale up for large-scale preparation. Background Art

[0002] Since 2004, when Geim and Novosolov prepared individual graphene sheets by micromechanical cleavage of graphite, graphene has demonstrated a variety of very important properties and applications. It has become one of the most studied materials among all nanomaterials and has triggered a research boom in two-dimensional materials. In addition to graphite, there are hundreds of similar layered materials, such as boron nitride (BN), transition metal dichalcogenides (TMDs), clays, MoS2, perovskites, COFs, etc. Two-dimensional materials prepared based on these layered materials currently show important application prospects in multiple fields such as electronics, energy, sensing, optics, catalysis, and drug carriers. So far, although various known two-dimensional materials can be prepared using classical micromechanical cleavage or chemical vapor deposition (CVD) methods, a key problem with both of these methods is that the cost is extremely high and batch preparation cannot be achieved.

[0003] Liquid-phase exfoliation is currently the most likely method to obtain a large amount of two-dimensional materials. However, liquid-phase exfoliation currently also faces a series of key problems. Generally speaking, the process of exfoliating two-dimensional materials from layered three-dimensional crystals is essentially a process of one-dimensional amorphization. The unique properties of two-dimensional materials mainly originate from interlayer decoupling and interlayer disorder. However, there are still strong interlayer interactions in existing layered crystal materials, especially when the lateral size of adjacent layers approaches infinity, which is also the key obstacle to liquid-phase exfoliation of two-dimensional materials. This also leads to the following key defects in two-dimensional materials prepared by this method: 1. Thickness non-uniformity. The exfoliated two-dimensional materials usually retain a certain degree of short-range order, resulting in thickness variations generally in the range from monolayer to dozens of layers. 2. Size limitation. The lateral size of the exfoliated two-dimensional materials is usually limited to the micron scale because reducing the lateral size helps to weaken interlayer interactions and couplings, thus achieving an interlayer disordered state. 3. Stability. In the absence of a substrate, two-dimensional materials are prone to re-stacking and recrystallization.

[0004] To overcome the shortcomings of liquid-phase exfoliation, two commonly used approaches are: First, intercalation between crystal layers using ionic species to increase the interlayer spacing and lower the energy barrier for exfoliation. Intercalation agents such as n-butyllithium or IBr can transfer charge between layers, reducing interlayer adhesion. Exfoliation can then be achieved through subsequent treatments such as thermal shock or sonication in liquids. However, this method still struggles to completely exfoliate the nanosheets, is sensitive to environmental conditions, involves multiple complex steps, and the intercalation process is slow. It is also difficult to scale up, and the range of 2D materials suitable for exfoliation by intercalation is very limited. Second, 2D materials can be stabilized through surface charge electrostatics or the addition of surfactants to prevent post-exfoliation aggregation. However, surfactants introduce additional challenges, severely hindering the application of 2D materials and failing to address the challenges of mass production. In summary, achieving low-cost, mass-produced high-quality 2D materials remains a key obstacle to their practical application and a technological bottleneck that urgently needs to be overcome. Summary of the Invention

[0005] The purpose of the present invention is to address the problems in the prior art and provide a type of two-dimensional material that can be self-exfoliated in a solvent and prepared in batches and has a high degree of layer thickness uniformity.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention discloses a two-dimensional material that can be prepared on a large scale by solvent self-exfoliation. The specific structure and preparation method are as follows:

[0008] (1) Select appropriate building block molecules and self-assemble to obtain a layered self-assembled structure with extremely weak interlayer forces. This self-assembled structure crystal is prone to one-dimensional amorphization under external conditions, resulting in the crystal having only long-range two-dimensional order.

[0009] (2) The building block molecules tend to form a layered porous structure, thereby greatly reducing the interlayer force; the building block molecules are tridentate ligands derived from triptycene; or cage molecules with different functional groups constructed by aromatic rings (Ar1) and aromatic heterocycles (Ar2), Ar1 is a benzene ring, triphenylbenzene, triphenyltriazine or tetraphenylethylene, the bridging atom X is C, O or N, Ar2 is a benzene ring, pyridine ring, triazine ring, pyrimidine ring or anthracene, and R is a carboxyl group, pyridine ring, 4-carboxylbenzene or imidazole ring.

[0010]

[0011] (3) Select metal ion linkers that match the building block molecules, and self-assemble with the building block molecules under suitable solvent and temperature conditions to form three-dimensional layered crystal materials.

[0012] Furthermore, the metal ion linker includes Cr 2+ , Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Zr 2+ , Cd 2+ ; The molar ratio of the addition of the three-dimensional block molecule to the metal ion is 1:2 - 10;

[0013] Furthermore, the preparation process of the three-dimensional layered crystal material is to add the three-dimensional block molecule and the metal ion into a reaction solvent in an appropriate ratio and react under solvothermal conditions in a sealed pressure-resistant container;

[0014] Furthermore, the reaction solvent for the reaction of the three-dimensional block molecule with the linker is N, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane or a mixture of two to three of them; the reaction temperature is 60 - 160 °C, and the reaction time is 4 - 120 h;

[0015] Furthermore, after the three-dimensional layered crystal material precipitates from the reaction solution, the crystal product is obtained by filtration, and the yield is 40 - 85%;

[0016] Furthermore, adding the three-dimensional layered crystal material into water, methanol, ethanol, acetic acid, tetrahydrofuran, dioxane, chlorobenzene, chloroform or a mixture of two to three of them, the crystal spontaneously exfoliates in the solvent to form a highly uniform two-dimensional material suspension, and the exfoliation process can be accelerated by shaking or heating and stirring, without other additional treatments, and is easy to scale up for large-scale preparation;

[0017] Furthermore, electron microscopy shows that the two-dimensional material in the suspension has a high monolayer property, has a lateral size ranging from several micrometers to hundreds of micrometers, and this two-dimensional material can form a stable aqueous suspension agent;

[0018] Furthermore, coating the two-dimensional material suspension agent on the surface of a substrate material or a porous material can be used as a template agent to prepare various nanoparticles or nano-devices, and can also be used as a micro-catalytic container, a catalyst precursor, a drug carrier, a coating additive, and an electronic sensor device.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The two-dimensional material of the present invention is prepared based on a one-dimensional amorphous crystal. The preparation method has a very simple process, high speed, low cost, and is easy to scale up. The obtained two-dimensional material has high quality, few defects, good monolayer property, a lateral size that can reach the millimeter level, and broad application prospects, providing an effective solution and new ideas for the problems that the preparation of existing two-dimensional nanosheets is limited to small scale, long cycle, and cannot be prepared in large quantities. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a single crystal structure diagram of the one-dimensional amorphous crystal constructed in Example 5 of the present invention.

[0022] Figure 2 It is an electron microscope photograph of the one-dimensional amorphous crystal constructed in Example 5 of the present invention.

[0023] Figure 3 It is a single crystal structure diagram of the one-dimensional amorphous crystal constructed in Example 6 of the present invention.

[0024] Figure 4 It is an electron microscope photograph of the one-dimensional amorphous crystal constructed in Example 6 of the present invention.

[0025] Figure 5 It is a self-peeling two-dimensional material aqueous solution prepared in Example 7 of the present invention and its obvious Tyndall effect.

[0026] Figure 6 It is an electron microscope photograph of the nanosheets in the self-peeling two-dimensional material aqueous solution prepared in Example 7 of the present invention.

[0027] Figure 7 It is an atomic force microscope photograph of the nanosheets in the self-peeling two-dimensional material aqueous solution prepared in Example 7 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The methods are conventional methods unless otherwise specified, and the raw materials can be obtained from public commercial channels unless otherwise specified. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the present invention.

[0029] Example 1: Preparation of building block molecule L1, Ar1 is a benzene ring, Ar2 is a pyrimidine ring, and R is a carboxyl group

[0030] Dissolve 2.5 g of phloroglucinol in 50 ml of DMF, and pour it into a separatory funnel to slowly drip it into a DMF (150 ml) solution containing 8.4 g of anhydrous potassium carbonate solid and 6 g of methyl 2,6-dichloropyrimidine-4-carboxylate. The reaction system is evacuated, and vigorously stirred at 70 °C for 3 hours. Pour in 400 ml of water and extract three times with ethyl acetate. After removing the organic phase, column chromatography gives 3.2 g of a white solid product with R being methyl ester. Dissolve this product in 50 ml of THF, and while stirring, drip into 30 ml of an aqueous solution in which 1.8 g of sodium carbonate is dissolved. Stir and react at room temperature for 10 hours. After the reaction is completed, remove the solvent, add hydrochloric acid to adjust the pH to 5 - 6, filter to collect the precipitate, and dry to obtain 2.6 g of a white solid product L1 (yield 87%). Example 2: Preparation of building block molecule L2, Ar1 is a benzene ring, Ar2 is a triazine ring, and R is 4-carboxyphenyl. Add 7.2 g of 2,4-dichloro-6-(p-tolyl)-1,3,5-triazine, 2.5 g of phloroglucinol, 8.4 g of anhydrous potassium carbonate, and 150 ml of DMF to a 250-ml single-necked flask, and vigorously stir and react at 70 °C for 3 hours. Pour in 400 ml of water and extract three times with dichloromethane. After removing the organic phase, recrystallize the residue with a mixed solution of dichloromethane and petroleum ether to obtain 6.4 g of a pale yellow crystalline compound with R being methyl (yield 48%). Add 2.5 g of chromium trioxide, 20 g of periodic acid, and 200 ml of acetonitrile to a 500-ml single-necked round-bottom flask, stir until the solid dissolves. This product with R being methyl is dissolved in 100 ml of a mixed solvent (acetonitrile:dichloromethane = 1:1), and gradually added dropwise to the reaction flask (15 minutes). The solution turns yellow, and continue to stir for 10 hours. After stopping the reaction, rotary evaporate to remove the reaction solvent, then wash the reactant with water and extract with ethyl acetate, dry over anhydrous sodium sulfate, filter off the solid, and concentrate to obtain a white crude product. Recrystallize the crude product in a mixed system of tetrahydrofuran and acetonitrile to obtain 6.2 g of a transparent rod-shaped crystal product L2 (yield 89%).

[0031] Example 3: Preparation of building block molecule L3, Ar1 is a benzene ring, Ar2 is a triazine ring, and R is imidazole

[0032] 6 g of cyanuric chloride was added to a 250 ml round-bottom flask, and 80 ml of THF was added to dissolve it in an ice-water bath. Secondly, 0.8 g of phloroglucinol was weighed and added to a 100 ml constant-pressure dropping funnel, and 50 ml of THF was added to dissolve it. Then 4 g of DIPEA was added, and then it was added dropwise to the solution of cyanuric chloride, and stirred at 0 °C for three hours. Recrystallization was carried out to obtain intermediate 1. Then 13.8 g of intermediate 1 and 100 ml of acetone were added to a 150 ml constant-pressure dropping funnel to dissolve it. 0.75 g of phloroglucinol was taken and added to a 150 ml constant-pressure dropping funnel, and 100 ml of acetone was added to dissolve it. Then 2.5 g of DIPEA was added, and then it was added dropwise to a round-bottom flask containing 200 ml of acetone and stirred for several hours. Intermediate 2 was obtained through a chromatography column. 0.6 g of imidazole and 1.2 g of DIPEA were taken and added to a 100 ml round-bottom flask, and 50 ml of THF was added to dissolve it. 1 g of intermediate 2 was taken in a 60 ml constant-pressure dropping funnel, and 30 ml of THF was added to dissolve it, and then it was added dropwise to the round-bottom flask and stirred at room temperature for several hours. It was filtered and washed three times with ethanol to obtain the white imidazole ligand L4.

[0033] Example 4: Preparation of one-dimensional amorphous crystals based on the building block molecule L1 and Zn ions

[0034] 0.1 - 0.3 mmol of L1 prepared in Example 1 and 0.9 - 0.27 mmol of zinc perchlorate hexahydrate were added to 80 mL of DMF, heated to 100 °C at a rate of 0.1 °C / min, maintained for 48 - 72 hours, and then cooled to room temperature at a rate of 1 °C / min. After filtration, colorless transparent crystals were obtained. Then, after heating and drying, one-dimensional amorphous crystals could be obtained.

[0035] Example 5: Preparation of one-dimensional amorphous crystals based on the building block molecule L2 and Mn ions

[0036] 0.1 - 0.3 mmol of L2 prepared in Example 2 and 0.9 - 0.27 mmol of manganese nitrate were added to 80 mL of DMF, heated to 120 °C at a rate of 0.1 °C / min, maintained for 48 - 72 hours, and then cooled to room temperature at a rate of 1 °C / min. After filtration, colorless transparent crystals were obtained. Then, after heating and drying, one-dimensional amorphous crystals could be obtained (as Figure 1 , Figure 2 shown).

[0037] Example 6: Preparation of one-dimensional amorphous crystals based on the building block molecule L2 and Cu ions

[0038] Add 0.1 - 0.3 mmol of L20 and 0.9 - 0.27 mmol of copper nitrate obtained in Example 2 to 80 mL of DMSO, heat it to 120 °C at a rate of 0.1 °C / min, keep it for 48 - 72 hours, then cool it to room temperature at a rate of 1 °C / min, filter it to obtain blue transparent crystals, and then heat and dry them to obtain one-dimensional amorphous crystals (such as Figure 3 , Figure 4 shown).

[0039] Example 7: Preparation of an aqueous solution of two-dimensional material from the one-dimensional amorphous crystal in Example 5

[0040] Put 1.0 g of the one-dimensional amorphous crystal obtained in Example 5 into 50 ml of water, shake well and oscillate for 2 minutes. The one-dimensional amorphous crystal can quickly dissolve in water to obtain a sol with an obvious Tyndall effect. A large number of uniform nanosheets with large lateral dimensions can be observed in the water by electron microscopy (such as Figure 5 , Figure 6 , Figure 7 shown).

[0041] Example 8: Preparation of a methanol solution of two-dimensional material from the one-dimensional amorphous crystal in Example 5

[0042] Put 1.0 g of the one-dimensional amorphous crystal obtained in Example 5 into 50 ml of methanol, heat it to 50 °C and stir. The one-dimensional amorphous crystal dissolves in methanol in a few minutes to obtain a sol with an obvious Tyndall effect.

[0043] Example 9: Preparation of a solution of two-dimensional material from the one-dimensional amorphous crystal in Example 6

[0044] Put 1.0 g of the one-dimensional amorphous crystal obtained in Example 6 into a mixed solvent of 100 ml of tetrahydrofuran and chlorobenzene (1:1), heat it to 50 °C and stir. The one-dimensional amorphous crystal dissolves in the mixed solvent of tetrahydrofuran and chlorobenzene within one hour to obtain a sol with an obvious Tyndall effect.

[0045] Example 10: Preparation of a solution of two-dimensional material from the one-dimensional amorphous crystal in Example 6

[0046] Put 1.0 g of the one-dimensional amorphous crystal obtained in Example 6 into 50 ml of chloroform, shake well and oscillate for 2 minutes. The one-dimensional amorphous crystal dissolves in the chloroform mixed solvent in a few minutes to obtain a sol with an obvious Tyndall effect.

[0047] Example 11: Preparation of a solution of two-dimensional material from the one-dimensional amorphous crystal in Example 4

[0048] Put 1.0 g of the one-dimensional amorphous crystal obtained in Example 4 into a mixed solvent of 50 ml of methanol and acetic acid (20:1), shake well and oscillate for 2 minutes. The one-dimensional amorphous crystal dissolves in the mixed solvent of methanol and acetic acid within a few minutes, and a sol with an obvious Tyndall effect is obtained. Example 12: Preparation of a two-dimensional material solution from the one-dimensional amorphous crystal in Example 4 Put 1.0 g of the one-dimensional amorphous crystal obtained in Example 4 into 100 ml of methanol, heat to 50 °C and stir. The one-dimensional amorphous crystal dissolves in methanol within several hours, and a sol with an obvious Tyndall effect is obtained.

[0049] Example 13: The aqueous solution of the two-dimensional material in Example 7 is used as a masking agent

[0050] Dilute the aqueous solution of the two-dimensional material obtained in Example 6 to 1 - 10 μg / L, take 1 ml and coat it on the surface of the substrate material (5 cm * 5 cm). After the water evaporates, a monolayer-distributed nanosheet coating is formed on the surface of the substrate material. Deposit a metal layer on the surface of the substrate material by CVD and control the thickness of the deposited layer to obtain a deposited layer with a thickness of nm. Then, decompose the surface two-dimensional material at high temperature, and periodically arranged metal sites can be obtained on the substrate surface.

[0051] Example 14: The aqueous solution of the two-dimensional material in Example 7 is used to construct single-atom dispersed manganese cluster sites on the surface Dilute the aqueous solution of the two-dimensional material obtained in Example 6 to 10 - 100 μg / L, adsorb the solution on the surface of the substrate material or porous material to form a monolayer-distributed nanosheet coating, and then decompose the two-dimensional material at high temperature. Periodically arranged manganese cluster sites can be obtained on the surface of the substrate material or porous material.

[0052] Example 15: The aqueous solution of the two-dimensional material in Example 7 is used as a drug carrier

[0053] Add an alcohol solution of drug molecules to the aqueous solution of the two-dimensional material obtained in Example 6. Since the drug molecules have poor water solubility and the two-dimensional material has hydrophobic cavities, the drug molecules can be adsorbed into the cavities, so that the drug molecules can dissolve in the sol and be adsorbed and stably exist in the pores of the two-dimensional material, thereby enhancing the drug stability; since the two-dimensional material in Example 7 itself has magnetism, it can realize the directional transport and enrichment of drugs under the action of an external magnetic field; it can also generate reactive oxygen species under near-infrared light irradiation to achieve photothermal therapy or photodynamic therapy, and produce a synergistic effect with drug therapy to improve the treatment effect of diseases such as tumors.

[0054] Example 16: The aqueous solution of the two-dimensional material in Example 7 is used as a microcatalytic container

[0055] The two-dimensional material obtained in Example 6 has hydrophobic cavities, so that the micro-molecular cavities can be used as containers in the aqueous solution to achieve the green chemical synthesis of organic compounds in the aqueous phase. For example, the two-dimensional material can selectively oxidize styrene to styrene oxide in the aqueous solution with a yield of 99.5%.

[0056] Example 17: The aqueous solution of the two-dimensional material in Example 7 is used as a catalyst precursor

[0057] The two-dimensional material obtained in Example 6 has hydrophobic cavities, so Pd(PPh3)4 can be dissolved in the aqueous solution of the two-dimensional material. Pd(PPh3)4 is fixed in the pores of the two-dimensional material, and further the two-dimensional material can be loaded on the surface of the catalyst support material, thereby forming a single-atom dispersed Pd catalyst on the surface of the support.

[0058] Example 18: The aqueous solution of the two-dimensional material in Example 7 is used as a coating additive

[0059] Adding the two-dimensional material obtained in Example 6 to the water-soluble coating can effectively enhance the strength and structural properties of the coating.

[0060] Example 19: The aqueous solution of the two-dimensional material in Example 7 is used as an electronic sensor device

[0061] Coating the two-dimensional material obtained in Example 6 onto the surface of the substrate material sputtered with microelectrodes can form a micro electronic sensor device responsive to the oxygen concentration when the two-dimensional nanosheets are just between the two microelectrodes.

[0062] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A two-dimensional material that can be prepared on a large scale by solvent self-exfoliation and its applications, characterized in that : One-dimensional amorphous crystals with extremely weak interlayer forces are prepared by self-assembly of building block molecules with three-dimensional structures and metal ion linkers. Without the aid of traditional mechanical exfoliation methods such as ultrasonic or ball milling, the one-dimensional amorphous crystals can self-exfoliate in solution to form a high-quality and highly monolayered two-dimensional material suspension. The preparation process is extremely simple, has a quantitative yield, extremely low cost, and is easy to scale up for large-scale preparation; the two-dimensional materials obtained by self-exfoliation of such one-dimensional amorphous crystals have few defects, good monolayer properties, and lateral dimensions up to millimeters; such water-soluble or lipid-soluble two-dimensional materials can be used as templating agents to prepare various nanoparticles or nanodevices, and can also be used as microcatalytic containers, catalyst precursors, drug carriers, coating additives, and electronic sensor devices.

2. As described in claim 1, the preparation characteristics of the one-dimensional amorphous crystals are as follows: The building block molecules and metal ions are added to the reaction solvent in an appropriate ratio and reacted under solvothermal conditions in a sealed pressure-resistant container; the reaction solvent is N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, or a mixture of two to three of them; the reaction temperature is 60 - 160 °C, and the reaction time is 4 - 120 h; after the crystals precipitate, they are washed and dried to obtain a yield of 40 - 85%.

3. As described in claim 1, the three-dimensional structure building block is characterized in that it has a three-dimensional spatial structure and is directly derived from triptycene; or it is a cage-shaped molecule with different functional groups constructed by an aromatic ring (Ar1) and a heteroaromatic ring (Ar2). Ar1 is a benzene ring, triphenylbenzene, triphenyltriazine, or tetraphenylethylene, the bridging atom X is C, O, or N, Ar2 is a benzene ring, pyridine ring, triazine ring, pyrimidine ring, or anthracene, and R is a carboxyl group, pyridine ring, 4-carboxybenzene, or imidazole ring.

4. According to claim 1, the metal ion linker is characterized in that: Common transition metal ions can form coordination bonds with the building block molecules, including Cr 2+ , Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Zr 2+ , Cd 2+ ; The molar ratio of the addition of the three-dimensional building block molecule to the metal ion is 1:2 - 10.

5. As described in claim 1, the preparation characteristics of the self-exfoliated two-dimensional materials are as follows: The one-dimensional amorphous crystals are added to water, methanol, ethanol, acetic acid, tetrahydrofuran, dioxane, chlorobenzene, chloroform, or a mixture of two to three of them, shaken or heated to 30 - 80 °C and stirred. Within 1 s - 24 h, the crystals spontaneously exfoliate in the solvent to form a highly uniform two-dimensional material suspension without any other special treatment. Such two-dimensional materials are easy to scale up for large-scale preparation.

6. As described in claim 1, the self-exfoliated two-dimensional materials are characterized in that they have a very high monolayer property, have lateral dimensions from several micrometers to hundreds of micrometers, and can form stable water-soluble or lipid-soluble suspensions.

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