A method for one-step realization of the intercalation and exfoliation of layered oxides to prepare large-size single-layer nanosheets
The preparation of large-sized single-layer nanosheets by the organic amine solution intercalation method solves the problems of wide thickness distribution and high preparation cost in the traditional liquid phase peeling method, and achieves efficient preparation of high-quality nanosheets.
Patent Information
- Application Number
- CN202411182849.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-27
- Publication Date
- 2025-07-11
- Estimated Expiration
- 2044-08-27
AI Technical Summary
It is difficult to efficiently prepare large-size single-layer nanosheets in the prior art. The traditional liquid-phase peeling method leads to a wide distribution of nanosheet thickness and requires multiple steps to increase the preparation cost.
The organic amine solution intercalation method is used to obtain large-sized single-layer nanosheets through the cationic coordination intercalation between the organic amine solution and the layered oxide layer, and then cleaned and oscillated in deionized water.
The efficient preparation of large-size single-layer nanosheets is achieved, which avoids lattice defects and stress-induced fractures, and improves the application operability of nanomaterials.
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Figure CN119059553B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of nanosheet materials, and particularly relates to a method for realizing the intercalation and exfoliation of layered oxides in one step to prepare large-size single-layer nanosheets. Background Technique
[0002] Large-size (the ratio of the diameter to the thickness of the nanosheet) two-dimensional (2D) nanosheet materials have always been one of the research focuses in the field of materials. The thickness of these materials is at the nanometer level, and the lateral size is at the micrometer level. To completely exfoliate layered materials to obtain single-layer nanosheets, the commonly used method is direct liquid-phase exfoliation. However, this method will result in a relatively wide thickness distribution of the nanosheets and a relatively small lateral size, and the basal plane of the obtained nanosheets may change significantly. So far, a small number of layered materials have been confirmed to spontaneously exfoliate to obtain single-layer nanosheets when immersed in an appropriate suspension medium. This thermodynamically driven exfoliation process is limited to charged layers and is similar to the dissolution process of salts. Due to the highly anisotropic binding between layers in layered materials (resulting in their flaky morphology), the dissolution occurs only in the stacking direction of charged layers. Therefore, such layered materials are also named "one-dimensional (1D) dissolution" materials. Other materials such as antimony phosphate, 2:1 type clay minerals, mullite or limonite type of titanate, layered perovskite, etc. all belong to this type of spontaneously exfoliating layered materials.
[0003] In the existing technology of preparing titanate nanosheets by spontaneous 1D dissolution, the main method is to exfoliate the nanosheets through a two-step process by liquid-phase exfoliation. Taking the traditional layered oxide, scaly hydrocalumite-type layered titanate K 0.8 Ti 1.73 Li 0.27 O4 as an example, the synthesis of the precursor needs to be obtained by solid-phase reaction at 1100 °C. The potassium ions between layers are repeatedly treated with strong acid HCl to exchange with hydrogen ions, making the basal plane acidic. At the same time, the lithium ions in the structure are completely leached out, and defects are generated in the layer structure (H 1.07 Ti 1.73 O4·H2O) due to the removal of lithium ions. Subsequently, the acidified protonated titanate solution is mixed with an aqueous solution of tetraalkylammonium hydroxide, for example, tetrabutylammonium hydroxide (TBAOH). The introduction of a strong base can not only provide a high charge density but also make the large cation (TBA + ) fully diffuse between layers, exceeding the threshold for the start of 1D dissolution. By adjusting the acidification time and different oscillation modes, Ti 0.87 O2- nanosheets with adjustable lateral size can be obtained.
[0004] Currently, the method of preparing nanosheets by ultrasonic treatment cannot provide precise size and structure control, inevitably resulting in a wide thickness distribution of the obtained nanosheets and flake fractures, thus failing to achieve the maximum aspect ratio inherent in the diameter of the original flakes. The nanosheets obtained by the traditional liquid-phase exfoliation method need to be further processed to be implemented in some applications, such as the formation of heterostructures, permeation-selective microporous membranes, textured (barrier) membranes or composite materials, which require nanosheets with uniform thickness and larger sizes. However, the current liquid-phase exfoliation method has a long preparation cycle and usually involves steps of ion exchange using hydrochloric acid or other strong acids, and the resulting waste acid treatment cost further increases the preparation cost of the nanosheets. Summary of the Invention
[0005] The present invention aims to solve the technical problems mentioned in the background art and provides a method for one-step realization of intercalation exfoliation of layered oxides to prepare large-size single-layer nanosheets. Its main principle is that the organic molecules containing amino groups in the organic amine solution coordinate and intercalate with the cations (such as sodium, potassium ions, etc.) between the layers of the layered oxides. After the layered material with the intercalated organic molecules containing amino groups is washed with ethanol solvent to remove the excess organic solution and redispersed in deionized water, high-quality and large-size nanosheets are obtained through sufficient shaking, mixing and centrifugation. The present invention uses an organic amine solution as the intercalation solvent, with high intercalation reaction efficiency and a relatively mild reaction pathway. During the exfoliation process, lattice defects caused by the ion escape in the structure are avoided, and stress-induced fracture during the exfoliation process is also inhibited, thereby obtaining nanosheets with significantly increased lateral dimensions, greatly improving the operability of the application of nanomaterials.
[0006] To achieve the above object, the present invention provides the following technical solutions:
[0007] A method for one-step realization of intercalation exfoliation of layered oxides to prepare large-size single-layer nanosheets, which mixes the layered oxides with an organic amine solution to obtain the layered oxides with enlarged interlayer spacing intercalated with the organic amine, washes to remove the excess organic amine solution, and then disperses it in deionized water and oscillates to obtain a dispersion of large-size single-layer nanosheets.
[0008] Further, the excess organic amine solution is removed by washing with ethanol; the oscillation is carried out on a shaker, aiming to uniformly disperse the large-size single-layer nanosheets in deionized water.
[0009] In the method for preparing large-size single-layer nanosheets of the present invention, the layered oxides are fully mixed with the organic amine solution, and a large number of organic molecules containing amino groups coordinate and intercalate with the metal cations between the layers of the layered oxides to obtain the layered oxides with enlarged interlayer spacing intercalated with the organic amine. The excess organic amine solution is removed by washing with ethanol, and then dispersed in deionized water, and sufficient oscillation is carried out on a shaker to obtain a dispersion of large-size single-layer nanosheets.
[0010] Furthermore, the initial lateral dimension of the layered oxide is 100 - 150 μm.
[0011] Furthermore, the layered oxide is a titanium-based oxide or a cobalt-manganese-based oxide. For example, the layered oxide is K 0.8 Ti 1.73 Li 0.27 O4 or NaCoMnO.
[0012] Furthermore, the organic amine in the organic amine solution is ethylenediamine hydrochloride, ifosfamide, ethyl carbamate or N-methylmethylamine.
[0013] Furthermore, the concentration of the organic amine solution is 0.5 - 5 mol / L.
[0014] Furthermore, during the coordination intercalation process, the organic amine solution is replaced every 12 - 48 h. Each time the organic amine solution is replaced, it is centrifuged at 10000 rpm for 10 minutes. After removing the supernatant, the organic amine solution is re-added.
[0015] Furthermore, the oscillation time is 1 - 7 days.
[0016] Furthermore, the oscillation time is 7 days.
[0017] Furthermore, the concentration of the large-size single-layer nanosheet dispersion is 0.5 - 2 mg / mL.
[0018] Furthermore, the large-size single-layer nanosheet has a lateral dimension of 10 - 20 μm and a thickness of 5 - 10 nm.
[0019] Compared with the prior art, the present invention has the following advantages and technical effects:
[0020] The method of directly obtaining nanosheets by coordination intercalation of amine-containing organic molecules in the present invention is superior to the existing exfoliation techniques. Usually, for the nanosheets obtained by the traditional liquid-phase exfoliation method with the addition of tetrabutylammonium hydroxide (TBAOH) in two steps of delamination, the diameter is 3 μm. However, the nanosheets obtained by the present invention can maintain a complete crystal structure under mild exfoliation process without generating defects. Therefore, they have higher mechanical strength, which significantly increases the diameter of the nanosheets, resulting in oxide nanosheets with a lateral dimension of 10 - 20 μm. The method of the present invention is applicable to the exfoliation of traditional layered oxides such as titanium oxide and cobalt-manganese-based oxides. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:
[0022] Figure 1 For K in Example 1 0.8 Ti 1.73 Li 0.27 SEM image of the KTiLiO4 precursor;
[0023] Figure 2 SEM image of the large-sized single-layer nanosheets after exfoliation in Example 1;
[0024] Figure 3 (H3O)EDA-TiLiO4 nanosheets (i.e., exfoliated nanosheets) solution optical image dispersed in ethylenediamine hydrochloride solution; 0.2 EDA 0.6 Ti 1.73 Li 0.27 Optical image of the solution of (H3O)EDA-TiLiO4 nanosheets (i.e., exfoliated nanosheets);
[0025] Figure 4 TEM image of the large-sized single-layer nanosheets exfoliated in Example 1;
[0026] Figure 5 For Na in Example 2 0.6 Mn 0.6 Co 0.4 SEM image of the NaMnO2 precursor;
[0027] Figure 6 SEM image of the large-sized single-layer nanosheets after exfoliation in Example 2;
[0028] Figure 7 TEM image of the large-sized single-layer nanosheets exfoliated in Example 2. Detailed implementation manners
[0029] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.
[0030] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.
[0031] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.
[0032] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the specification of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of this invention are obvious to those skilled in the art. The specification and examples of this invention are merely illustrative.
[0033] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.
[0034] Unless otherwise specified, the room temperature in the embodiments of this invention is measured as 25 ± 2°C.
[0035] All raw materials used in the embodiments of this invention are obtained by purchasing commercially.
[0036] The embodiments of this invention provide a method for achieving the intercalation and exfoliation of layered oxides in one step to prepare large-sized single-layer nanosheets. The layered oxides are mixed with an organic amine solution to obtain layered oxides with an increased layer spacing and coordinated intercalation of amino-containing organic molecules. The excess organic amine solution is removed by washing, and then it is dispersed in deionized water and oscillated to obtain a large-sized single-layer nanosheet dispersion.
[0037] In some embodiments of this invention, the excess organic amine solution is removed by washing with ethanol; the oscillation is carried out on a shaker, aiming to uniformly disperse the large-sized single-layer nanosheets in deionized water.
[0038] In the method for preparing large-sized single-layer nanosheets of this invention, the layered oxides are fully mixed with an organic amine solution, and a large number of amino-containing organic molecules coordinate and intercalate with the metal cations between the layers of the layered oxides to obtain layered oxides with an increased layer spacing and organic amine intercalation. The excess organic amine solution is removed by washing with ethanol, and then it is dispersed in deionized water and fully oscillated on a shaker to obtain a large-sized single-layer nanosheet dispersion.
[0039] In some embodiments of this invention, the initial lateral size of the layered oxides is 100 - 150 μm.
[0040] In some embodiments of the present invention, the layered oxide is a titanium-based oxide or a cobalt-manganese-based oxide. For example, the layered oxide is K 0.8 Ti 1.73 Li 0.27 O4 or NaCoMnO.
[0041] In some embodiments of the present invention, the organic amine in the organic amine solution is ethylenediamine hydrochloride, ifosfamide, ethyl carbamate, N-methylmethylamine. In some embodiments of the present invention, the concentration of the organic amine solution is 0.5 - 5 mol / L (0.5 - 5 M). For example, the concentration of the organic amine solution can be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L.
[0042] In some embodiments of the present invention, during the coordination intercalation process, the organic amine solution is replaced every 12 - 48 h. Each time the organic amine solution is replaced, centrifuge at 10000 rpm for 10 minutes. After removing the supernatant, add the organic amine solution again.
[0043] In some embodiments of the present invention, the oscillation time is 1 - 7 days. For example, the oscillation time can be 1 day, 1.5 days, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days. Preferably, the oscillation time is 7 days.
[0044] In some embodiments of the present invention, the concentration of the large-size single-layer nanosheet dispersion is 0.5 - 2 mg / mL.
[0045] In some embodiments of the present invention, the lateral size of the large-size single-layer nanosheet is 10 - 20 μm, and the thickness is 5 - 10 nm.
[0046] The technical solution of the present invention is further described below through examples.
[0047] In the following examples, the preparation method of the K 0.8 Ti 1.73 Li 0.27 O4 precursor is as follows: Take potassium carbonate, titanium dioxide, and lithium oxide powders, mix and grind them evenly, then heat them in a muffle furnace in air to 1100 °C for 20 h. After annealing, a K 0.8 Ti 1.73 Li 0.27 O4 precursor with a lateral size of 100 μm is obtained. Extend the heating time to 48 h, and a K 0.8 Ti 1.73 Li 0.27 O4 precursor with a lateral size of 150 μm can be obtained after annealing.
[0048] Example 1
[0049] Disperse 500 mg of K 0.8 Ti 1.73 Li 0.27 O4 precursor (initial lateral size of 150 μm) in 50 mL of 1 M ethylenediamine hydrochloride solution, stir at room temperature for 72 h, and perform replacement to obtain layered (H3O) 0.2 EDA 0.6 Ti 1.73 Li 0.27 O4 material. Replace the ethylenediamine hydrochloride solution every 24 h. Centrifuge at 10000 rpm for 10 minutes. After removing the supernatant, add the ethylenediamine hydrochloride solution again and repeat the subsequent operations to obtain a sample after coordination intercalation with an amino-containing organic molecule;
[0050] Wash the sample after coordination intercalation with an amino-containing organic molecule twice with ethanol to remove the excess ethylenediamine hydrochloride solution. Add 100 mL of deionized water to 100 mg of the sample after coordination intercalation with an amino-containing organic molecule and shake in a shaker for 1 week (7 days) to obtain a dispersion of large-sized single-layer nanosheets after complete exfoliation (concentration of 1 mg / mL). The lateral size of the nanosheets is 20 μm and the thickness is 5 nm.
[0051] Figure 1 For the scanning electron microscope image of the K 0.8 Ti 1.73 Li 0.27 O4 precursor in Example 1, it can be seen that the precursor has an obvious layered structure and the size is 150 μm;
[0052] Figure 3 For the optical image of the (H3O) 0.2 EDA 0.6 Ti 1.73 Li 0.27 O4 nanosheet (i.e., the exfoliated nanosheet) solution in aqueous solution, it can be seen that the dispersion and exfoliation effect of the nanosheets is good;
[0053] Figure 2 For the scanning electron microscope image of the large-sized single-layer nanosheets after exfoliation in Example 1, Figure 4 For the transmission electron microscope image of the large-sized single-layer nanosheets obtained by exfoliation in Example 1, it can be seen that the thickness of the single-layer nanosheets is nanoscale and the exfoliation effect is good.
[0054] Example 2
[0055] Na 0.6 Mn 0.6 Co 0.4The synthesis method of O2 is as follows: Dissolve Mn(CH3COO)2·4H2O, Co(CH3COO)2·4H2O and NaNO3 in pure water according to the stoichiometric ratio (0.6:0.4:0.6), and dry overnight on a hot plate at 130 °C. The obtained precipitate is annealed in air at 300 °C for 20 h, and then heated in air at 750 °C for 20 hours. After annealing, Na 0.6 Mn 0.6 Co 0.4 O2 powder is obtained.
[0056] Disperse 500 mg of Na 0.6 Mn 0.6 Co 0.4 O2 (with an initial lateral size of 100 μm) in 50 mL of 1 M N-ethylenediamine hydrochloride solution, stir at room temperature for 72 h to obtain layered (H3O) 0.2 EDA 0.6 Co 0.8 Mn 1.2 O4 material. Replace the ethylenediamine hydrochloride solution every 12 h, centrifuge at 10000 rpm for 10 minutes, remove the supernatant, and then re-add the ethylenediamine hydrochloride solution. Repeat the subsequent operations to obtain a sample after intercalation with an amino-containing organic molecule coordination;
[0057] Wash the sample after intercalation with an amino-containing organic molecule coordination twice with ethanol to remove the excess ethylenediamine hydrochloride solution. Add 50 mL of deionized water to 100 mg of the sample after intercalation with an amino-containing organic molecule coordination, and oscillate in a shaker for 4 days to obtain a dispersion of fully exfoliated large-size single-layer nanosheets (Co 0.4 Mn 0.6 O2) (with a concentration of 2 mg / mL). The lateral size of the nanosheets is 12 μm and the thickness is 5 nm.
[0058] Figure 5 For the scanning electron microscope image of the Na 0.6 Mn 0.6 Co 0.4 O2 precursor in Example 2, it can be seen that the precursor has an obvious layered structure and the size is 100 μm;
[0059] Figure 6 For the scanning electron microscope image of the large-size single-layer nanosheets after exfoliation in Example 2, it can be seen that the lateral size of the precursor is 12 μm.
[0060] Figure 7 For the transmission electron microscope image of the large-size single-layer nanosheets exfoliated in Example 2, it can be seen that the thickness of the single-layer nanosheets is at the nanometer level and the exfoliation effect is good.
[0061] Example 3
[0062] Same as Example 1, except that the 1M ethylenediamine hydrochloride solution is replaced with 2M ifosfamide. After peeling, the lateral size of the nanosheets is 15 μm and the thickness is 10 nm.
[0063] Example 4
[0064] Disperse 500 mg of K 0.8 Ti 1.73 Li 0.27 O4 (initial lateral size of 100 μm) in 50 mL of 1M ethyl carbamate solution, stir at room temperature for 96 h, perform replacement to obtain a layered material coordinated with amino-containing organic molecules. Replace the ethyl carbamate solution every 48 h. Centrifuge at 10,000 rpm for 10 minutes. After removing the supernatant, add ethyl carbamate solution again;
[0065] Wash the sample intercalated with amino-containing organic molecules twice with ethanol to remove the excess ethyl carbamate solution. Add 50 mL of deionized water to 100 mg of the sample intercalated with amino-containing organic molecules, and oscillate in a shaker for 3 days to obtain a dispersion of large-sized single-layer nanosheets after complete peeling (concentration of 2 mg / mL). The lateral size of the nanosheets is 10 μm and the thickness is 5 nm.
[0066] Example 5
[0067] Disperse 500 mg of K 0.8 Ti 1.73 Li 0.27 O4 (initial lateral size of 100 μm) in 50 mL of 0.5M N-methylmethylamine solution, stir at room temperature for 72 h, perform replacement to obtain a layered material coordinated with amino-containing molecules. Replace the N-methylmethylamine solution every 48 h. Centrifuge at 10,000 rpm for 10 minutes. After removing the supernatant, add N-methylmethylamine solution again;
[0068] Wash the sample intercalated with amino-containing organic molecules twice with ethanol to remove the excess N-methylmethylamine solution. Add 200 mL of deionized water to 100 mg of the sample intercalated with amino-containing organic molecules, and oscillate in a shaker for 1 day to obtain a dispersion of large-sized single-layer nanosheets after complete peeling (concentration of 0.5 mg / mL). The lateral size of the nanosheets is 10 μm and the thickness is 10 nm.
[0069] Example 6
[0070] Same as Example 1, except that the concentration of the ethylenediamine hydrochloride solution is 2M. At this time, the amino-containing organic molecules coordinate and intercalate with the metal cations between the layered oxides. The lateral size of the nanosheets in this example is 15 μm and the thickness is 10 nm.
[0071] Example 7
[0072] Same as Example 1, except that the concentration of the ethylenediamine hydrochloride solution is 5 M. At this time, the amino-containing organic molecules coordinate and intercalate with the metal cations between the lamellar oxide layers. The lateral size of the nanosheets in this example is 10 μm, and the thickness is 10 nm.
[0073] Example 8
[0074] Same as Example 1, except that the concentration of the ethylenediamine hydrochloride solution is 0.5 M. At this time, the amino-containing organic molecules coordinate and intercalate with the metal cations between the lamellar oxide layers. The lateral size of the nanosheets in this example is 15 μm, and the thickness is 5 nm.
[0075] Comparative Example 1 Traditional method (the method of Patent CN 113443655 A)
[0076] K2CO3, Li2CO3 and TiO2 were ground and mixed in a molar ratio of 0.4∶0.14∶1.73, placed in a Pt crucible, decarbonized at 800 °C for 1 h, and ground again for 30 min after cooling. Finally, the sample was calcined in a Pt crucible at 1100 °C for 1 week to prepare the scolecite-type layered titanate K 0.8 Ti 1.73 Li 0.27 O4. Subsequently, 1 mol / L hydrochloric acid was added, mixed and stirred. The proton exchange time was 2 days to obtain acidified H 1.07 Ti 1.73 O4·H2O. By calculating the concentration of H ions in the acidified sample, an equal-concentration tetrabutylammonium hydroxide solution was added, and the mixture was oscillated in a shaker for one week to fully neutralize the H ions bound to the interlayer, thereby obtaining a monolayer nanosheet dispersion. The lateral size of the nanosheets is only 3 μm, and the thickness is 1 - 5 nm.
[0077] It can be seen that the traditional tetrabutylammonium hydroxide liquid-phase exfoliation method involves acidification ion exchange and treatment with tetrabutylammonium hydroxide solution. The aspect ratio of the obtained nanosheets is much smaller than the result obtained by the present invention. At the same time, the waste acid treatment cost increases the preparation cost of the nanosheets, and the steps are cumbersome, hindering the subsequent application of the nanosheets.
[0078] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims
1. A method for one-step realizing the intercalation and exfoliation of layered oxides to prepare large-size single-layer nanosheets, characterized in that Mix the layered oxide with an organic amine solution to obtain a layered oxide intercalated with organic amine with an increased layer spacing. Wash to remove the excess organic amine solution, and then disperse it in deionized water and shake to obtain a dispersion of large-size single-layer nanosheets; The initial lateral size of the layered oxide is 100 - 150 μm; The organic amine in the organic amine solution is ethylenediamine hydrochloride, ifosfamide, ethyl carbamate or N-methylmethylamine; The lateral size of the large-size single-layer nanosheets is 10 - 20 μm and the thickness is 5 - 10 nm; The layered oxide is a titanium-based oxide or a cobalt-manganese-based oxide.
2. The method for preparing large-size single-layer nanosheets by one-step realizing the intercalation and exfoliation of layered oxides according to claim 1, wherein The concentration of the organic amine solution is 0.5 - 5 mol / L.
3. The method for one-step realizing the intercalation and exfoliation of layered oxides to prepare large-size single-layer nanosheets according to claim 1, characterized in that, The shaking time is 1 - 7 days.
4. The method for preparing large-sized single-layer nanosheets by one-step realizing intercalation and exfoliation of layered oxides according to claim 3, characterized in that The shaking time is 7 days.