A two-dimensional sheet material based on electrostatic interaction and a method for regulating the interlayer spacing size thereof and applications thereof

Abstract

The application discloses a two-dimensional sheet material based on electrostatic interaction and a method for regulating the interlayer spacing size thereof and application, and belongs to the technical field of film material preparation. In the application, a functional polymer or small molecule containing an easy-hydrolyzable functional group is introduced between the two-dimensional material sheet layers. The functional polymer / small molecule as a whole is negatively or positively charged by regulating the hydrolysis and ionization of the functional group of the functional polymer / small molecule, so that the charging density of the intercalated polymer or small molecule is improved, and significant electrostatic repulsion is introduced between the adjacent sheet layers to overcome the interlayer van der Waals force and drive the continuous expansion of the interlayer structure. Furthermore, ions with opposite electric properties to the charged groups are introduced to realize the coordination of the charged groups and the ions to achieve charge compensation, inhibit or adjust the expansion, so that the interlayer space size can be regulated in a wide range, accurately and reversibly.

Description

Technical Field

[0001] This invention belongs to the field of membrane material preparation technology, specifically relating to a two-dimensional sheet material based on electrostatic interaction, a method for controlling the interlayer spacing size, and its application. Background Technology

[0002] Assembling two-dimensional materials (such as MXene, graphene oxide, layered oxides / sulfides, and layered clays) into nanostructured membranes is one of the important ways to transform two-dimensional materials from the nanoscale to macroscopic devices and engineering applications. Within these nanostructured membranes, the confined interlayer space maintained by van der Waals interactions between adjacent layers forms interlayer nanochannels, endowing these membrane materials with unique physicochemical properties. The spatial dimensions of these interlayer nanochannels (e.g., interlayer spacing, effective pore size) have a significant impact on efficient ion migration, ion / molecular selective sieving, and enhanced surface / interface reactivity, which is of great significance for promoting technological advancements in applications such as energy conversion, seawater desalination, and selective molecular ion separation. Therefore, how to achieve precise, controllable, and reversible adjustment of the interlayer spatial dimensions, especially achieving a wide controllable range spanning orders of magnitude and maintaining stability within different size ranges, has become one of the key technical issues for improving the comprehensive performance and application adaptability of layered membrane materials.

[0003] To achieve interlayer spatial size control, existing technologies typically employ intercalation control and surface functionalization control. Intercalation control often involves introducing small organic molecules, polymer segments, inorganic ions, or nanoparticles as supporting / pillar components to alter the interlayer spacing. For example, patent CN107640765A discloses immersing a graphene oxide (GO) film in a salt solution containing metal cations, allowing the metal cations to enter the interlayer and induce swelling, thus achieving size adjustment of the interlayer channels, but its control range is only about 1 nm. Surface functionalization control involves introducing functional groups or grafted molecules onto the surface of the sheets to adjust the interlayer interactions (e.g., hydrogen bonding, van der Waals interactions, electrostatic interactions, etc.), thereby achieving a certain degree of interlayer structural change. In addition, related technologies also include methods such as solvent or humidity-induced swelling, cross-linking curing, and chemical reduction / oxidation to adjust the interlayer structure. For example, patent CN116059846A describes how graphene oxide (GO) films swell in water, leading to an increase in interlayer size. It also describes how "covalent crosslinking" improves underwater structural stability to achieve interlayer size control. However, it cannot control the interlayer size to any value (low control precision) and the control range is only 2-7 nm (narrow control range). Patent CN105084355B describes how partially reduced graphene oxide (prGO) is introduced to construct layered graphene oxide films. This improves the stability of the film in water / acid / alkali solutions without introducing crosslinking agents. The interlayer size is adjusted by the degree / content of prGO reduction. However, it is difficult to reversibly return to the original oxidation level and the original interlayer structure. Therefore, the above-mentioned control methods usually still have certain defects: on the one hand, the adjustable range of interlayer spacing is relatively limited, and it can often only achieve small changes within the nanoscale, which is difficult to meet the channel size requirements of a wider scale; on the other hand, the control process is easily affected by factors such as intercalation content, reaction degree, and swelling kinetics, which makes it impossible to achieve precise control of interlayer size; in addition, some schemes are accompanied by uncontrollable chemical reactions or strong interaction lock, which can easily cause structural solidification, making the interlayer structure exhibit irreversible control.

[0004] In view of this, it is necessary to address the common problems of narrow adjustable range, insufficient precision, and difficulty in reversible adjustment of interlayer space size in existing layered membrane materials. A technical solution should be proposed that enables precise, controllable, and reversible adjustment of the interlayer space across a wide scale range (nm-mm level). This solution would allow for precise adjustment and reversible control of the interlayer channel size while maintaining the integrity and mechanical stability of the layered membrane structure. This would promote the widespread application and full utilization of various two-dimensional membrane materials in emerging application fields such as energy conversion, separation, and sensing. Summary of the Invention

[0005] This invention provides a two-dimensional sheet material based on electrostatic interaction, a method for controlling the interlayer spacing size, and its application. This method can solve the problems of narrow adjustable range, insufficient control precision, and difficulty in reversible adjustment that are common in the control of interlayer space size of existing layered film materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for controlling the interlayer spacing of a two-dimensional sheet material based on electrostatic interactions includes the following steps: Introducing functional polymers or small molecules containing easily hydrolyzable functional groups between the layers of two-dimensional sheet materials, and regulating the electrostatic repulsion force by controlling the hydrolysis of the functional groups of functional polymers or small molecules, thereby driving the cross-scale expansion of the interlayer spacing. By introducing ions with opposite charges to the charged functional groups, they can coordinate with the charged functional groups to achieve charge compensation, suppress or reverse expansion, and achieve fine adjustment of surface charge and interlayer repulsion strength, thereby enabling wide-range, precise and reversible control of interlayer space size.

[0007] In the steps described above, the two-dimensional sheet material includes, but is not limited to, MXene, graphene oxide, layered oxides / sulfides, and vermiculite.

[0008] The functional polymer or small molecule containing easily hydrolyzable functional groups is a functional polymer or small molecule containing easily hydrolyzable functional groups such as carboxyl groups; preferably carboxylated cellulose CNF-COOH or chitosan; Introducing ions with opposite charges to the functional groups, including but not limited to monovalent, divalent, or trivalent cation systems, with Li being preferred. + Na + K + Ca 2+ Zn 2+ Al 3+ Furthermore, the degree of coordination can be adjusted by combining salt concentration and soaking time, thereby achieving precise setting of the interlayer structure.

[0009] The aforementioned two-dimensional sheet material based on electrostatic interaction includes: a two-dimensional sheet material and a functional polymer or small molecule containing easily hydrolyzable functional groups located between the sheets; the functional polymer or small molecule containing easily hydrolyzable functional groups is inserted into the interlayer of the two-dimensional sheet material to provide a variable charge source for subsequent electrostatic control.

[0010] Beneficial effects: This invention provides a two-dimensional sheet material based on electrostatic interactions, a method for controlling the interlayer spacing, and its applications, which have the following advantages compared with existing technologies: 1. The method for controlling the interlayer spacing of two-dimensional sheet materials based on electrostatic interaction provided by this invention solves the problems of narrow adjustable range, insufficient control precision, and difficulty in reversible adjustment that are common in the control of interlayer space size of existing layered film materials. This invention can achieve continuous adjustment of the interlayer structure in multiple orders of magnitude through the synergistic mechanism of deprotonation / protonation-induced electrostatic repulsion and coordination charge compensation: the porosity can be increased from 0% to 78%, the interlayer spacing can be expanded from 1.39nm to 0.152mm, and the film thickness can be increased from 43μm to 5400μm, which significantly broadens the structural design space of traditional methods.

[0011] 2. The interlayer spacing size control method of the present invention can achieve performance optimization for different applications on the same material system by simply setting different interlayer spacing / channel sizes: the small expansion of the interlayer spacing (1.48nm) increases the zinc ion capacitance by 67%; the 21583-fold expansion (channel about 30μm) increases the permeation energy conversion power by 63%; and the 100719-fold expansion (channel about 140μm) endows the device with excellent pressure sensing capability.

[0012] 3. The method of the present invention is applicable to various two-dimensional material films such as vanadium carbide (V2C), graphene oxide (GO), vanadium pentoxide (V2O5), graphitic carbon nitride (g-C3N4), molybdenum disulfide (MoS2), and vermiculite (VMT). For example, GO film and VMT film achieved approximately 94 times and 112 times thickness expansion respectively within 24 hours, indicating that the two-dimensional film interlayer spacing size control method based on electrostatic interaction provided by the present invention has good universality and applicability to various two-dimensional layered material film systems. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of deprotonation-induced interlayer expansion in an embodiment of the present invention; Figure 2 These are optical photographs of the two-dimensional sheet material in this embodiment of the invention, showing deprotonation-induced expansion and ion coordination-induced recovery within 36 hours. Figure 3 These are optical photographs of the MXene@CNF-COOH film at different expansion ratios in embodiments of the present invention; Figure 4 These are cross-sectional SEM images of the film under different expansion ratios in the embodiments of the present invention, as well as the corresponding magnified interlayer spacing. Figure 5 The Zeta potential of the original MXene, CNF-COOH, and MXene@CNF-COOH membranes in the embodiments of the present invention changes with NaCl concentration; Figure 6This is a curve showing the change in thickness of the deprotonated composite membrane immersed in NaCl solutions of different concentrations over time in an embodiment of the present invention. Figure 7 In the embodiments of the present invention, the solution is soaked in a solution with a concentration of 10. -3 Curves showing the change in thickness of the deprotonation membrane over time in different salt solutions of M; Figure 8 This refers to the change in composite film thickness over time after step-by-step control in this embodiment of the invention. Figure 9 These are optical photographs of V2C, TiVNbMoC3, GO, V2O5, g-C3N4, MoS2 and VMT films in embodiments of the present invention; Figure 10 This is a customized application of the control membrane in the embodiments of the present invention, wherein (a) and (b) are the ZIC performance based on composite membranes with an expansion ratio of 1 to 1.31 times: (a) the specific capacitance changes with the expansion ratio, (b) the specific capacitance changes with the scan rate under different expansion ratios; (c) and (d) are the permeation energy conversion performance of membranes with expansion ratios ranging from 1 to 20 times: (c) the power density changes, (d) the dependence of load resistance under different expansion ratios; (e) and (f) are the piezoresistive performance of membranes with expansion ratios ranging from 47 to 98 times: (e) sensitivity, (f) sensitivity-pressure curves under different expansion ratios. Detailed Implementation

[0014] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments: Preparation method of Ti3C2MXene two-dimensional film: A concentration of 1-5 mg / ml -1 A self-supporting membrane was prepared from a commercial Ti3C2MXene dispersion by vacuum-assisted filtration. After vacuum drying at 50-80℃ for 10-12 hours, a flexible Ti3C2MXene membrane was successfully obtained.

[0015] Preparation method of GO two-dimensional membrane: A concentration of 1-5 mg / ml -1 A self-supporting membrane was prepared from a commercial GO dispersion by vacuum-assisted filtration, and a flexible GO membrane was successfully obtained after vacuum drying at 50-80℃ for 10-12 hours.

[0016] Method for preparing V2O5 two-dimensional membranes: A concentration of 1-5 mg / ml -1 A self-supporting membrane was prepared from a commercial V2O5 dispersion by vacuum-assisted filtration. After vacuum drying at 50-80℃ for 10-12 hours, a flexible V2O5 membrane was successfully obtained.

[0017] Preparation method of MXene@CNF-COOH two-dimensional membrane: (1) Add 5-10 mL of Ti3C2MXene dispersion (5-10 mg / mL) -1 ) with different volumes (0–15 mL) of CNF-COOH dispersion (5–10 mg / mL) -1 Mix according to the predetermined ratio.

[0018] (2) While maintaining magnetic stirring at 800 rpm, CNF-COOH solution was added dropwise to the MXene dispersion. Subsequently, the mixture was sonicated in an ice bath for 3-6 minutes to ensure uniform distribution of the nanosheets.

[0019] (3) The mixture was vacuum filtered to form a membrane, and then heat-treated in a vacuum drying oven at 50-80℃ for 10-12 hours to obtain a self-supporting composite membrane.

[0020] Preparation method of two-dimensional membranes with deprotonated MXene@CNF-COOH: (1) Cut the composite film into 1×1cm pieces. 2 Soak it in 20-30mL of deionized water.

[0021] (2) Utilizing the hydrolysis property of the carboxyl group (-COOH) in a neutral to weakly alkaline environment, a deprotonation reaction is performed to generate a negatively charged carboxylate ion (-COO). - ).

[0022] (3) The degree of deprotonation is dynamically adjusted by carefully controlling the soaking time in the solution.

[0023] Preparation of ion-coordinated MXene@CNF-COOH two-dimensional membranes: (1) Place the composite membrane sample (1×1cm) 2 Soak in 20-30 mL of solution with a concentration gradient of 10. -4 Cation coordination was carried out in a 1M chloride salt solution.

[0024] (2) Negatively charged -COO - Groups interact with cations through electrostatic interactions, promoting charge neutralization and regulating interfacial properties.

[0025] (3) Six representative cations Li were selected + Na + K + (Monovalent), Ca 2+ Zn 2+ (Divalent) and Al 3+ A comparative analysis was conducted on the trivalent (trivalent) products.

[0026] (4) Ion coordination degree is dynamically controlled by precise solution concentration gradient and soaking time.

[0027] Preparation and electrochemical testing of supercapacitors (1) An MXene@CNF film was obtained by vacuum filtration. After natural drying, it was cut to an appropriate size and adhered to a glass substrate. Electrodes based on MXene@CNF were obtained by laser engraving.

[0028] (2) Using a deprotonation-ion coordination strategy, using 10 -3 Pretreatment for different times (10, 15, 30, 45, and 60 minutes) yielded MXene@CNF-COOH-based electrodes. These were then assembled into a symmetrical supercapacitor. (3) Performance was tested using a Chi760 electrochemical workstation, including cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements. The electrolyte was 1M H₂SO₄, and the effective electrode area was 0.5 cm². 2 The voltage window is 0-0.6V.

[0029] Fabrication and Electrical Measurement of Penetration Energy Devices (1) The prepared GO@CNF-COOH membrane with a specific thickness is installed between the two chambers of the custom electrochemical cell.

[0030] (2) Ion transport measurements were performed using a Keithley 6487 semiconductor picoammeter. A pair of homemade Ag / AgCl electrodes were used to acquire current and voltage signals. Subsequent energy conversion tests were performed by connecting the power supply to an adjustable resistance box.

[0031] (3) For a given resistance (R), the formula for calculating the output power density is P=I 2 ×R. The effective test membrane area is approximately 3 × 10⁻⁶. 4 μm 2 .

[0032] Fabrication and Electrical Measurement of Piezoresistive Sensors (1) A piezoresistive sensor was developed using MXene@CNF-COOH with flexible interdigitated electrodes. Specifically, we fine-tuned the MXene@CNF-COOH film using a deprotonation-ion coordination strategy to achieve the fabrication of films with different thicknesses.

[0033] (2) Freeze-drying technology is used to stabilize its porous structure and remove moisture. The encapsulation process is completed using a thermoplastic film.

[0034] (3) To evaluate the performance of the piezoresistive sensor, this invention establishes a measurement system comprising a constant current source (Agilent B2901A), a controlled stepper motor, and a force gauge. During the testing phase and practical application of this piezoresistive sensor, the applied voltage is set to 1V.

[0035] Example 1

[0036] A two-dimensional film interlayer spacing size control method based on electrostatic interactions was employed, using MXene, CNF-COOH, and Na... + Interlayer spacing was controlled, and electrochemical tests were performed using MXene@CNF.

[0037] (1) Preparation method of Ti3C2MXene two-dimensional film: A concentration of 5 mg / ml -1 Commercial Ti3C2MXene dispersions were used to prepare self-supporting membranes via vacuum-assisted filtration. After vacuum drying at 60°C for 12 hours, flexible Ti3C2MXene membranes were successfully obtained.

[0038] (2) Preparation method of MXene@CNF-COOH two-dimensional membrane: 6 mL of commercial Ti3C2MXene dispersion (5 mg / mL) -1 ) and different volumes (0–15 mL) of CNF-COOH dispersion (5 mg / mL) -1 Mix according to the predetermined ratio. The specific mixing process is as follows: While maintaining magnetic stirring at 800 rpm, CNF-COOH solution was added dropwise or directly to the MXene dispersion; subsequently, the mixture was sonicated in an ice bath for 3 minutes to ensure uniform distribution of nanosheets. The resulting mixture was vacuum filtered to form a membrane, which was then heat-treated in a vacuum drying oven at 60°C for 12 hours to obtain a self-supporting composite membrane.

[0039] (3) Preparation method of two-dimensional membrane of deprotonated MXene@CNF-COOH: The resulting self-supporting composite membrane was cut into 1×1cm pieces. 2 It is then soaked in 20 mL of deionized water. Utilizing the hydrolysis property of the carboxyl group (-COOH) in a neutral to weakly alkaline environment, a deprotonation reaction occurs to generate negatively charged carboxylate ions (-COO₂). - The degree of deprotonation is dynamically adjusted by carefully controlling the soaking time in the solution. For example... Figures 1-4 As shown, the strong electrostatic repulsion between adjacent MXene layers can dynamically drive the film thickness to expand by several orders of magnitude. After 24 hours, the film thickness increased from 43 μm to 5400 μm, with an expansion ratio as high as 12560%.

[0040] (4) Preparation of ion-coordinated MXene@CNF-COOH two-dimensional membranes: The resulting deprotonated MXene@CNF-COOH two-dimensional membrane sample (1×1 cm) 2 Soak in a 20 mL solution with a concentration gradient of 10. -4 Cation coordination occurs in a 1M NaCl salt solution, with the negatively charged -COO - Groups interact with cations through electrostatic interactions, promoting charge neutralization and regulating interfacial properties. Ion coordination degree is dynamically controlled through precise solution concentration gradients and soaking times. For example... Figure 5 As shown, with increasing NaCl concentration, the Zeta potentials of MXene, CNF-COOH, and MXene@CNF-COOH films gradually increased, indicating that their surface charge was effectively regulated; Figure 6 As shown, the thickness of the deprotonated composite membrane immersed in NaCl solutions of different concentrations decreases with increasing NaCl solution concentration. This regulation originates from NaCl concentration. + Coordination occurs with deprotonation sites on CNF and MXene surfaces, where the negative charge is partially neutralized through a charge compensation mechanism. Maximum expansion of the composite film occurs 24 hours after deprotonation under NaCl-free (0M) conditions.

[0041] Preparation and electrochemical testing of supercapacitors MXene@CNF films were obtained through vacuum filtration, naturally dried, cut to appropriate sizes, and adhered to a glass substrate. Electrodes based on MXene@CNF were then obtained through laser engraving. Based on this, a deprotonation-ion coordination strategy was employed, using 10... -3 Electrodes based on MXene@CNF-COOH were obtained by pretreating M H2SO4 for different times (10, 15, 30, 45, and 60 minutes). These were assembled into symmetrical supercapacitors, and their performance was tested using a chi760 electrochemical workstation, including cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements. The electrolyte was 1 M H2SO4, and the effective electrode area was 0.5 cm². 2 The voltage window is 0-0.6V. For example... Figure 10 As shown in (a) and (b), the best ZIC performance is achieved at approximately 1.14 times expansion.

[0042] Example 2

[0043] A two-dimensional film interlayer spacing size control method based on electrostatic interactions was developed, employing GO, CNF-COOH, and K... + Interlayer spacing was controlled, and electrochemical tests were performed using MXene@CNF.

[0044] (1) Preparation method of GO@CNF-COOH two-dimensional membrane: Add 6 mL of commercial GO dispersion (5 mg mL) -1 ) and different volumes (0–15 mL) of CNF-COOH dispersion (5 mg / mL) -1 Mix according to the predetermined ratio.

[0045] While maintaining magnetic stirring at 800 rpm, the CNF-COOH solution was added dropwise to the GO dispersion. The mixture was then sonicated in an ice bath for 3 minutes to ensure uniform distribution of the nanosheets. The resulting mixture was vacuum filtered to form a membrane, which was subsequently heat-treated in a vacuum drying oven at 60°C for 12 hours to obtain a self-supporting composite membrane.

[0046] (2) Preparation method of two-dimensional membrane of deprotonated GO@CNF-COOH: Cut the composite film into 1×1cm pieces. 2 The sample was then soaked in 20 mL of deionized water. Utilizing the hydrolysis property of the carboxyl group (-COOH) in a neutral to weakly alkaline environment, a deprotonation reaction was performed to generate a negatively charged carboxylate ion (-COO₂). - The degree of deprotonation can be dynamically adjusted by carefully controlling the soaking time in the solution.

[0047] (4) Preparation of ion-coordinated GO@CNF-COOH two-dimensional membranes: The composite membrane sample (1×1cm) 2 Soak in 20 mL of solution with a concentration gradient of 10 -4 Cation coordination occurs in a 1M KCl salt solution. The negatively charged -COO₂... - The functional groups interact with cations through electrostatic interactions, promoting charge neutralization and regulating interfacial properties. Ion coordination degree is dynamically controlled through precise solution concentration gradients and soaking times.

[0048] Fabrication and Electrical Measurement of Penetration Energy Devices A pre-prepared GO@CNF-COOH membrane of a specific thickness was installed between the two chambers of a custom electrochemical cell. Ion transport measurements were performed using a Keithley 6487 semiconductor picoammeter. A pair of homemade Ag / AgCl electrodes were used to acquire current and voltage signals, and subsequent energy conversion tests were performed by connecting the power supply to an adjustable resistance box. For a given resistance (R), the output power density was calculated using the formula P = I. 2 ×R. The effective test membrane area is approximately 3 × 10⁻⁶. 4 μm 2 .like Figure 10 As shown in (c) and (d), the optimal permeability conversion performance is achieved at approximately 10 times expansion.

[0049] Example 3

[0050] A two-dimensional film interlayer spacing size control method based on electrostatic interactions was adopted, using MXene, CNF-COOH, and Li + Interlayer spacing was controlled, and electrochemical tests were performed using MXene@CNF.

[0051] (1) Preparation method of MXene@CNF-COOH two-dimensional membrane: Add 6 mL of MXene dispersion (5 mg mL) -1 ) and different volumes (0–15 mL) of CNF-COOH dispersion (5 mg / mL) -1 Mix according to the predetermined ratio. The specific mixing process is as follows: While maintaining magnetic stirring at 800 rpm, the CNF-COOH solution was added dropwise to the MXene dispersion. The mixture was then sonicated in an ice bath for 3 minutes to ensure uniform distribution of the nanosheets. The resulting mixture was vacuum filtered to form a membrane, which was subsequently heat-treated in a vacuum drying oven at 60°C for 12 hours to obtain a self-supporting composite membrane.

[0052] (2) Preparation method of two-dimensional membrane of deprotonated MXene@CNF-COOH: Cut the composite film into 1×1cm pieces. 2 The sample was then soaked in 20 mL of deionized water. Utilizing the hydrolysis property of the carboxyl group (-COOH) in a neutral to weakly alkaline environment, a deprotonation reaction was performed to generate a negatively charged carboxylate ion (-COO₂). - The degree of deprotonation can be dynamically adjusted by carefully controlling the soaking time in the solution.

[0053] (3) Preparation of ion-coordinated MXene@CNF-COOH two-dimensional membranes: The composite membrane sample (1×1cm) 2 Soak in 20 mL of solution with a concentration gradient of 10 -4 Cation coordination occurs in a 1M LiCl salt solution. The negatively charged -COO₂... - The functional groups interact with cations through electrostatic interactions, promoting charge neutralization and regulating interfacial properties. Ion coordination degree is dynamically controlled through precise solution concentration gradients and soaking times.

[0054] Fabrication and Electrical Measurement of Piezoresistive Sensors A piezoresistive sensor employing flexible interdigitated electrodes was developed using MXene@CNF-COOH. Specifically, the MXene@CNF-COOH film was fine-tuned using a deprotonation-ion coordination strategy to achieve fabrication at different thicknesses. Subsequently, freeze-drying was used to stabilize its porous structure and remove moisture. Encapsulation was performed using a thermoplastic film. To evaluate the performance of the piezoresistive sensor, a measurement system comprising a constant current source, a controlled stepper motor, and a force gauge was established. During the testing phase and practical application of this piezoresistive sensor, the applied voltage was set to 1V. Figure 10 As shown in (e) and (f), the piezoresistive sensor achieves optimal performance at an expansion ratio of approximately 78.

[0055] like Figure 7 As shown, soaking in a solution of 10% concentration -3 The expansion of the deprotonation membrane in different salt solutions of M decreases significantly with increasing ionic valence. At the same concentration of 10... -3 At time M, high charge Al 3+ The degree of expansion caused by coordination is only that of Na. + The coordination efficiency is 0.51 times higher. This is because high-valence cations can more effectively neutralize the negative charge on the CNF and MXene surfaces.

[0056] Figure 8 The thickness of the composite membrane changes over time after stepwise control. The deprotonation process is carried out from 0 to 24 hours, followed by ion coordination control using NaCl solutions of different concentrations from 24 to 48 hours. After 24 hours of deprotonation, the thickness of the composite membrane reaches 5400 μm. After exposing the membrane sample to NaCl solutions of different concentrations for 24 hours, its thickness shows a gradual recovery (shrinkage) trend as the NaCl concentration increases, and the degree of recovery gradually increases.

[0057] Figure 9 These are optical photographs of two-dimensional materials V2C, TiVNbMoC3, GO, V2O5, g-C3N4, MoS2, and VMT films, demonstrating uniform expansion achieved through a two-dimensional film interlayer spacing size control method based on electrostatic interactions. This proves the universality of the size control method provided by this invention in controlling the interlayer spacing of various two-dimensional materials.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling the interlayer spacing of a two-dimensional sheet material based on electrostatic interactions, characterized in that, Includes the following steps: Introducing functional polymers or small molecules containing easily hydrolyzable functional groups between the layers of two-dimensional sheet materials, and regulating the electrostatic repulsion force by controlling the hydrolysis of the functional groups of functional polymers or small molecules, thereby driving the cross-scale expansion of the interlayer spacing. By introducing ions with opposite charges to the charged functional groups, they can coordinate with the charged functional groups to achieve charge compensation, suppress or reverse expansion, and achieve fine adjustment of surface charge and interlayer repulsion strength, thereby enabling wide-range, precise and reversible control of interlayer space size.

2. The method for controlling the interlayer spacing of two-dimensional sheet materials based on electrostatic interactions according to claim 1, characterized in that, The specific steps for introducing functional polymers or small molecules containing easily hydrolyzable functional groups between the layers of a two-dimensional sheet material are as follows: Preparation of two-dimensional layered materials; A solution of a functional polymer or small molecule containing easily hydrolyzable functional groups is added dropwise to a dispersion of a two-dimensional layered material. After ultrasonic treatment and homogenization, the mixture is vacuum filtered and dried to obtain a self-supporting composite membrane. This process introduces the functional polymer or small molecule containing easily hydrolyzable functional groups into the interlayer space of the two-dimensional layered material.

3. The method for controlling the interlayer spacing of two-dimensional sheet materials based on electrostatic interactions according to claim 1, characterized in that, In neutral or weakly alkaline environments, the functional polymers or small molecules containing easily hydrolyzable functional groups introduced between the layers of two-dimensional sheet materials undergo hydrolysis, making the polymers or small molecules as a whole negatively or positively charged. This introduces significant electrostatic repulsion between adjacent layers, overcomes the interlayer van der Waals effect, and drives the interlayer structure to expand continuously.

4. The method for controlling the interlayer spacing of two-dimensional sheet materials based on electrostatic interactions according to claim 3, characterized in that, The degree of interlayer structural expansion can be controlled by dynamically adjusting the charge density through immersion time in a neutral or weakly alkaline environment.

5. The method for controlling the interlayer spacing of two-dimensional sheet materials based on electrostatic interactions according to claim 1 or 3, characterized in that, The specific steps to achieve charge compensation are as follows: the two-dimensional layered material that has expanded after hydrolysis is added to a solution with opposite electrical properties, and coordinates with charged functional groups to achieve charge compensation, thereby suppressing or reversing the expansion.

6. The method for controlling the interlayer spacing of a two-dimensional sheet material based on electrostatic interaction according to claim 5, characterized in that, The degree of expansion is dynamically controlled by adjusting the concentration gradient and soaking time of solutions with opposite electrical properties.

7. The method for controlling the interlayer spacing of a two-dimensional sheet material based on electrostatic interaction according to claim 1, characterized in that, The functional polymer or small molecule containing easily hydrolyzable functional groups is a functional polymer or small molecule containing carboxyl groups or chitosan.

8. The method for controlling the interlayer spacing of a two-dimensional sheet material based on electrostatic interaction according to claim 1, characterized in that, The two-dimensional sheet materials include MXene, graphene oxide, layered oxides, layered sulfides, and vermiculite.

9. The two-dimensional sheet material based on electrostatic interaction in the control method according to any one of claims 1-8, characterized in that, include: Two-dimensional sheet materials and functional polymers or small molecules containing easily hydrolyzable functional groups located between the sheets; Functional polymers or small molecules containing easily hydrolyzable functional groups are inserted into the interlayer of two-dimensional sheet materials, and subsequent electrostatic modulation provides a variable charge source.

10. The application of the two-dimensional sheet material based on electrostatic interaction as described in claim 9, characterized in that, Used to prepare supercapacitors, osmotic energy devices, or piezoresistive sensors.

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