Two-dimensional material confined ionic liquid composite membrane, and preparation method and application thereof

Abstract

The application discloses a two-dimensional material confined ionic liquid composite film and a preparation method and application thereof. The two-dimensional material confined ionic liquid composite film comprises a two-dimensional material and an ionic liquid, and the ionic liquid is confined in the interlayer and / or channel of the two-dimensional material. The preparation method comprises the following steps: compounding the two-dimensional material and the ionic liquid and self-assembling to obtain the two-dimensional material confined ionic liquid composite film. By compounding the two-dimensional material and the ionic liquid, the large specific surface area and excellent physical and chemical properties of the two-dimensional material are fully utilized, effective confined space is provided for the ionic liquid, the diffusion speed of the gas and the response speed of the sensing film are significantly improved, and the stability and long-term reliability of the gas sensor are improved. In addition, the prepared sensing film can efficiently detect various harmful gases, has strong gas adsorption capacity and electrochemical performance, and provides a novel high-performance gas sensing material for environmental monitoring, industrial production and air quality control.

Description

Technical Field

[0001] This invention relates to a composite membrane, specifically to a two-dimensional material confined ionic liquid composite membrane, its preparation method, and its application, belonging to the field of new material membrane gas sensing technology. Background Technology

[0002] With the continuous advancement of industrialization, the emission of gaseous pollutants has become increasingly serious, especially harmful gases such as nitrogen oxides (NOx). x Gases such as carbon dioxide (CO2) and volatile organic compounds (VOCs) pose a significant threat to air quality and human health. Monitoring and detecting gaseous pollution is crucial for ensuring environmental safety, public health, and the sustainability of industrial production. Furthermore, the application of gas sensing technology in non-invasive disease diagnosis is receiving increasing attention, especially with breakthroughs in achieving high sensitivity, rapid response, and selectivity at room temperature. These technologies are of great significance for timely monitoring of harmful gas emissions, reducing environmental pollution, protecting the ecological environment, and diagnosing non-invasive diseases.

[0003] Ionic liquids (ILs) are a class of liquid salts formed by the electrostatic interaction of organic and inorganic cations and anions, typically existing as liquids at room temperature. Compared to traditional solvents, ionic liquids possess many unique advantages, such as extremely low vapor pressure, excellent thermal stability, a wide liquid window, and tunable physicochemical properties, leading to their widespread application in chemistry, materials science, environmental protection, and energy. In the field of gas sensors, ionic liquids, due to their strong interactions with various gas molecules, exhibit good gas adsorption capacity and excellent electrochemical performance, and are often used as gas adsorption media and sensing materials. However, the high viscosity of ionic liquids limits the gas diffusion rate, reducing the response speed of gas sensors. Furthermore, the high fluidity and difficulty in solidification of individual ionic liquids make it challenging to form stable device structures, limiting their long-term stability and performance in practical applications. Summary of the Invention

[0004] The main objective of this invention is to provide a two-dimensional material confined ionic liquid composite membrane and its preparation method, so as to overcome the shortcomings of the prior art.

[0005] Another object of the present invention is to provide the application of the two-dimensional material confined ionic liquid composite membrane.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: This invention provides a two-dimensional material confined ionic liquid composite membrane, which includes a two-dimensional material and an ionic liquid, wherein the ionic liquid is confined within the interlayer and / or pores of the two-dimensional material.

[0007] In some embodiments, the two-dimensional material includes any one or a combination of two or more of metal-organic frameworks, covalent organic frameworks, graphene, and transition metal dichalcogenides.

[0008] In some embodiments, the ionic liquid comprises any one or a combination of two or more of the following: 1-butyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoromethanesulfonylimide, 1-ethyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imide.

[0009] This invention also provides a method for preparing a two-dimensional material-confined ionic liquid composite membrane, which includes: combining a two-dimensional material and an ionic liquid and self-assembling them to obtain a two-dimensional material-confined ionic liquid composite membrane.

[0010] This invention also provides the application of the two-dimensional material confined ionic liquid composite membrane in the preparation of gas sensors.

[0011] Furthermore, embodiments of the present invention also provide a gas sensor, including a gas sensing membrane, wherein the gas sensing membrane includes the aforementioned two-dimensional material confined ion liquid composite membrane.

[0012] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1) This invention combines two-dimensional nanomaterials with ionic liquids. Utilizing the excellent solubility of ionic liquids and the high specific surface area of ​​two-dimensional nanomaterials, the adsorption capacity of gas molecules is enhanced, thereby increasing the response sensitivity of the gas sensor. This composite material design significantly improves the detection sensitivity of low-concentration gases, and also exhibits rapid response time and strong selectivity. 2) This invention uses two-dimensional nanomaterials as the reinforcing phase of the gas sensor. The combination with ionic liquids not only improves the problem of insufficient adsorption sites in traditional gas sensing materials but also enhances the selectivity of the sensor among different gases. The high surface activity of the two-dimensional nanomaterials and the optimized modulation function of the ionic liquids effectively improve the sensor's response accuracy to specific gases. 3) The two-dimensional nanomaterial confined ion liquid composite gas sensor prepared by this invention has high stability and long service life, and can operate stably under various environmental conditions. This gas sensor can not only effectively detect gases at high temperatures, low temperatures or extreme humidity, but also has low operating costs and a simple preparation process, and has broad application potential in environmental monitoring, industrial control and other fields. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 A photograph of the COF nanosheet confined ionic liquid composite film prepared in Example 1 of this invention; Figure 2 This is the infrared spectrum of the COF nanosheet confined ionic liquid composite film prepared in Example 1 of this invention; Figure 3 This is a performance graph of gas detection of the COF nanosheet confined ionic liquid composite membrane prepared in Example 1 of this invention; Figure 4 This is a stability test diagram of the MOF nanosheet confined ionic liquid composite film prepared in Example 2 of the present invention; Figure 5 This is a schematic diagram of the graphene-confined ionic liquid composite film prepared in Example 3 of the present invention; Figure 6 This is a test graph showing the sensing performance of the COF nanosheet confined ionic liquid composite membrane prepared in Example 5 of this invention. Figure 7 This is a test graph of the sensing performance of the COF nanosheet confined ionic liquid composite membrane prepared in Example 8 of the present invention. Figure 8 This is a graph showing the sensing performance of the COF nanosheet confined ionic liquid composite membrane prepared in Comparative Example 1. Figure 9 The graph shows the sensing performance test results of the COF nanosheet confined ionic liquid composite membrane prepared in Comparative Example 2. Figure 10 This is a graph showing the test performance of the carbon black composite ionic liquid membrane material prepared in Comparative Example 3. Detailed Implementation

[0015] To address the aforementioned technical problems in the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The main invention is a composite membrane based on a two-dimensional material confining an ionic liquid and its preparation method. By confining a highly fluid and viscous ionic liquid within the interlayer and channels of a two-dimensional material, the composite membrane can effectively promote mass transfer through its abundant channel structure, thereby improving the performance and response speed of the gas sensor. This aims to solve the problems of slow response speed and poor long-term stability caused by the high viscosity of ionic liquids in existing gas sensors.

[0016] To facilitate understanding of this application, it will be described in more detail below. However, it should be understood that the invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to provide a thorough and complete understanding of the disclosure of this invention.

[0017] Specifically, as one aspect of the technical solution of the present invention, a two-dimensional material confined ionic liquid composite membrane includes a two-dimensional material and an ionic liquid, wherein the ionic liquid is confined in the interlayer and / or pores of the two-dimensional material.

[0018] The composite membrane provided by this invention utilizes the interlayer and pores of two-dimensional materials to confine highly viscous ionic liquids, enabling mass transfer through abundant pathways.

[0019] In some preferred embodiments, the two-dimensional material may include any one or a combination of two or more of metal-organic frameworks (MOFs), covalent organic frameworks (COFs), graphene, and transition metal dichalcogenides (TMDs), but is not limited thereto. Two-dimensional materials are a class of materials with two-dimensional structures that have attracted widespread attention due to their unique physical and chemical properties. Two-dimensional materials such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), graphene, and transition metal dichalcogenides (TMDs) all possess abundant layered structures and large specific surface areas, enabling them to provide effective confinement space for ionic liquids.

[0020] Furthermore, the two-dimensional material is preferably a two-dimensional material nanosheet. Specifically, covalent organic framework (COF) nanosheets can be prepared by a low-temperature (10 ~ 20 ℃) ​​two-phase solvent diffusion method.

[0021] Furthermore, the specific surface area of ​​the two-dimensional material is 50~7000 m². 2 / g, the porosity of the two-dimensional material is >10%.

[0022] Furthermore, the pore size of the two-dimensional material is 0.1~20nm.

[0023] In some preferred embodiments, the ionic liquid may include any one or more combinations of [BMIM][OAc] (1-butyl-3-methylimidazolium acetate), [EMIM][OAc] (1-ethyl-3-methylimidazolium acetate), [BMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate), [EMIM][TFSI] (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine), [EMIM][PF6] (1-ethyl-3-methylimidazolium hexafluorophosphate), [BMIM][TFSI] (1-butyl-3-methylimidazolium trifluoromethanesulfonylimine), [EMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate), and [P14][TFSI] (1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imine), but is not limited thereto.

[0024] In some preferred embodiments, the mass ratio of the two-dimensional material to the ionic liquid is 1:(100~1000).

[0025] In some preferred embodiments, the thickness of the two-dimensional material confined ionic liquid composite film is 0.5 μm to 20 μm.

[0026] As another aspect of the technical solution of the present invention, a method for preparing a two-dimensional material confined ionic liquid composite membrane includes: combining two-dimensional materials and ionic liquids and self-assembling them to obtain a two-dimensional material confined ionic liquid composite membrane.

[0027] In some embodiments, the preparation method specifically includes: mixing the two-dimensional material with a first solvent to obtain a two-dimensional material nanosheet solution.

[0028] In some embodiments, the preparation method specifically includes: mixing the ionic liquid with a second solvent to obtain an ionic liquid dispersion.

[0029] In some embodiments, the preparation method specifically includes: combining a two-dimensional material nanosheet solution and an ionic liquid dispersion by low-temperature ultrasonication, and depositing them onto a porous membrane by vacuum-assisted self-assembly to obtain the two-dimensional material confined ionic liquid composite membrane.

[0030] In some preferred embodiments, the preparation method specifically includes the following steps: (1) Preparation of two-dimensional material nanosheet solution; (2) Preparation of ionic liquid dispersion; (3) Two-dimensional material nanosheet solution and ionic liquid dispersion are composited by low temperature ultrasonication and deposited on porous membrane by vacuum-assisted self-assembly.

[0031] In some preferred embodiments, in step (1), the first solvent in the two-dimensional material nanosheet solution can uniformly disperse the two-dimensional material in the solvent by ultrasound and stirring. Specifically, the first solvent may include any one or a combination of two or more of acetone, ethanol, and water (such as deionized water), but is not limited to this.

[0032] In some preferred embodiments, in step (2), the second solvent includes any one or more combinations of water (such as ultrapure water), methanol, ethanol, DMSO (dimethyl sulfoxide), DMF (dimethylformamide), ethylene glycol, toluene, dichloromethane, chloroform, n-hexane, etc., but is not limited thereto.

[0033] In some preferred embodiments, in step (3), the process conditions for the low-temperature ultrasonic composite include: temperature of -5~15℃, ultrasonic power of 120W~720W, and ultrasonic time of 10 min~1h.

[0034] Furthermore, in step (3), the vacuum degree is 0.08 MPa~0.1 MPa when performing vacuum-assisted self-assembly.

[0035] In summary, the preparation method provided by this invention is simple to operate and highly reproducible. This invention combines two-dimensional nanomaterials (such as MOF, COF, graphene, etc.) with ionic liquids, utilizing the excellent solubility of ionic liquids and the high specific surface area and excellent physicochemical properties of two-dimensional nanomaterials to enhance the adsorption capacity of gas molecules and improve the response sensitivity of the gas sensor. Through the design of this composite material, the detection sensitivity of low-concentration gases can be significantly improved, and it exhibits rapid response time and strong selectivity.

[0036] The innovative design of this invention not only significantly improves the gas diffusion rate and the response speed of the sensing membrane, but also enhances the stability and long-term reliability of the gas sensor.

[0037] Furthermore, the prepared sensing membrane can efficiently detect a variety of harmful gases, such as NO. x It possesses strong gas adsorption capacity and electrochemical performance for gases such as CO2 and VOCs, providing a novel high-performance gas sensing material for environmental monitoring, industrial production, and air quality control.

[0038] As another aspect of the technical solution of the present invention, it also relates to the application of the aforementioned two-dimensional material confined ionic liquid composite membrane in the preparation of gas sensors.

[0039] Furthermore, another aspect of the present invention provides a gas sensor including a gas sensing membrane, said gas sensing membrane comprising the aforementioned two-dimensional material confined ion liquid composite membrane.

[0040] This invention employs two-dimensional nanomaterials as the reinforcing phase of a gas sensor. The combination with ionic liquids not only improves the problem of insufficient adsorption sites in traditional gas sensing materials but also enhances the sensor's selectivity among different gases. Furthermore, the high surface activity of the two-dimensional nanomaterials and the optimized modulation function of the ionic liquids effectively improve the sensor's response accuracy to specific gases.

[0041] The two-dimensional nanomaterial confined ion liquid composite gas sensor prepared by this invention exhibits high stability and long service life, and can operate stably under various environmental conditions. This gas sensor can effectively detect gases not only at high temperatures, low temperatures, or extreme humidity, but also boasts low operating costs and a simple fabrication process, demonstrating broad application potential in fields such as environmental monitoring and industrial control.

[0042] The present invention is further illustrated by the following embodiments: The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the specific material ratios, process conditions, and results described in the embodiments are for illustrative purposes only and should not, and will not, limit the present invention as described in detail in the claims.

[0043] Unless otherwise specified, the various raw materials, reaction equipment, testing equipment and testing methods used in the following embodiments are all known in the art.

[0044] Example 1 The preparation method of a COF nanosheet confined ionic liquid in this embodiment includes the following steps: 1) Preparation of COF nanosheet solution: 0.6 mmol of 2,4,6-trihydroxybenzene-1,3,5-tricarboxaldehyde (Tp) was dissolved in 100 ml of n-octanoic acid to obtain an organic phase solution. Then, 0.9 mmol of 1,4-phenylenediamine-2-sulfonic acid (Pa-SO3H) was added to 150 ml of deionized water and dissolved to obtain an aqueous phase solution. The organic phase solution was then added dropwise onto the aqueous phase solution as a top layer. The reaction was carried out at 16℃ under static conditions for 4 days. After the reaction, the organic phase solution was removed. The aqueous phase solution was collected and centrifuged at 10,000 rpm for 10 min to remove the precipitate. The obtained aqueous phase solution was dialyzed in deionized water for 1–3 days to obtain a TpPa-SO3H nanosheet colloidal solution. The concentration of COF nanosheets can be calculated by freeze-drying or UV absorption spectroscopy.

[0045] 2) Preparation of ionic liquid solution: Add 1 g of [BMIM][TFSI] ionic liquid to 10 ml of ethanol solvent and stir until well mixed.

[0046] 3) The COF nanosheet solution prepared in step 1) and the ionic liquid solution prepared in step 2) are mixed uniformly at a solid mass ratio of 1:200, and ultrasonically treated at -5℃ for 30 min with an ultrasonic power of 600W. The COF / ionic liquid composite solution is deposited on the PVDF film by a vacuum-assisted method (vacuum degree of 0.08 MPa).

[0047] Testing showed that the COF nanosheet confined ionic liquid gas sensing film material prepared by the above method exhibits strong mechanical stability and flexibility. Its optical morphology is shown in the image below. Figure 1 As shown, the surface is smooth and uniform. Infrared spectroscopy analysis reveals... Figure 2 As shown, it can be confirmed that COF nanosheets and ionic liquids coexist stably in the membrane material, and the ionic liquids are effectively confined within the COF nanosheet structure through chemical interactions. Gas sensing performance test results ( Figure 3 As shown in the figure, the membrane material can effectively detect acetone gas concentrations ranging from 1 ppm to 100 ppm.

[0048] Example 2 The preparation method of a MOF nanosheet confined ionic liquid in this embodiment includes the following steps: 1) Preparation of MOF nanosheet solution: Dissolve 0.1 mmol HHTP in 20 mL of H2O / EtOH (1:1) mixed solvent, add 0.8 wt% Tween 80 and 0.1 wt% PVA, and sonicate for 10 minutes until completely dissolved. Dissolve 0.2 mmol CuCl2·2H2O in another 20 mL H2O / EtOH (1:1) solution and stir magnetically for 5 minutes until clear. Add the HHTP solution to the CuCl2 solution via a peristaltic pump or dropwise (approximately 1 mL / min) while maintaining magnetic stirring (300 rpm). Allow the reaction to stand at room temperature for 24 hours, avoiding stirring disturbance (to reduce particle agglomeration).

[0049] 2) Preparation of ionic liquid solution: Add 1 g of [BMIM][TFSI] ionic liquid to 10 ml of H2O / EtOH (1:1) mixed solvent and stir until the mixture is homogeneous.

[0050] 3) The MOF nanosheet solution prepared in step 1) and the ionic liquid solution prepared in step 2) were uniformly mixed at a solid mass ratio of 1:300, and ultrasonically treated at 10°C for 15 min with an ultrasonic power of 720 W. Then, the MOF / ionic liquid composite solution was deposited on the surface of a PVDF membrane using a vacuum-assisted method (vacuum degree of 0.08 MPa) to obtain a MOF nanosheet confined ionic liquid gas sensing membrane material.

[0051] The MOF nanosheet-confined ionic liquid gas sensing membrane prepared by the above method exhibits excellent sensing performance for ammonia. Specifically, the membrane shows a response of 2.4% to 200 ppm ammonia, while the response to 1000 ppm ammonia significantly improves to 14%. Furthermore, the membrane was subjected to a stability test for ten cycles at a 1000 ppm ammonia concentration, demonstrating excellent stability and good repeatability (e.g., ...). Figure 4 (As shown).

[0052] Example 3 The preparation method of a graphene nanosheet confined ionic liquid in this embodiment includes the following steps: 1) Preparation of graphene nanosheet solution: 0.1 g of graphene oxide was dispersed in 100 mL of anhydrous ethanol and ultrasonically treated in an ice-water bath for 1 h using a cell disruptor to promote the exfoliation of graphene nanosheets. Unexfoliated large graphene particles were removed by centrifugation to obtain an aqueous solution of graphene nanosheets.

[0053] 2) Add 2 g of ionic liquid [EMIM][TFSI] to 20 ml of methanol and stir until completely dissolved.

[0054] 3) The graphene nanosheet solution prepared in step 1) and the ionic liquid solution prepared in step 2) were uniformly mixed at a solid mass ratio of 1:800, and ultrasonically treated at 5°C for 30 min with an ultrasonic power of 360W. Then, the graphene / ionic liquid composite solution was deposited on the surface of a polyimide (PI) film using a vacuum-assisted method (vacuum degree of 0.09 MPa) to obtain a graphene nanosheet confined ionic liquid gas sensing film material.

[0055] The graphene nanosheet confined ionic liquid gas sensing film prepared by the above method was cut into 1×1 cm pieces and connected to electrodes as follows. Figure 5 As shown, further gas sensing tests were conducted, and the device responded to ethanol gas.

[0056] Example 4 This embodiment is based on a method for preparing transition metal dichalcogenide (TMD) nanosheet confined ionic liquids, and the specific process is as follows: 1) Preparation of TMDs nanosheet dispersion: 0.05 g of molybdenum disulfide (MoS2) powder was dispersed in 50 mL of isopropanol solvent and treated with an ultrasonic homogenizer for 2 hours under ice-water bath conditions. Then, the unpeeled particles were removed by centrifugation at 3000 rpm for 10 minutes, and finally a uniform TMDs nanosheet dispersion was obtained.

[0057] 2) Preparation of ionic liquid solution: Dissolve 1 g of [BMIM][BF4] ionic liquid in 10 mL of methanol and stir at room temperature until completely transparent.

[0058] 3) The TMDs dispersion prepared in step 1) was mixed with the ionic liquid solution at a solute mass ratio of 1:500, and ultrasonically treated at 0℃ for 30 min to achieve uniform composite. The ultrasonic power was 480W. Subsequently, the composite solution was loaded onto the surface of a flexible polytetrafluoroethylene (PTFE) substrate using a vacuum-assisted film formation process (vacuum degree of 0.08MPa), and after drying, a TMDs nanosheet confined ionic liquid composite film was obtained.

[0059] Based on the layered structure of TMDs and the confinement enhancement effect of ionic liquids, the material was tested and found to have an electrical signal response to hydrogen sulfide (H2S) gas.

[0060] Example 5 The preparation method of a COF nanosheet confined ionic liquid in this embodiment includes the following steps: 1) The preparation method of COF nanosheets in this embodiment is the same as that in Example 1.

[0061] 2) Preparation of ionic liquid solution: Add 1 g of [BMIM][OAc] ionic liquid to 10 ml of ethanol solvent and stir until well mixed.

[0062] 3) The COF nanosheet solution prepared in step 1) and the ionic liquid solution prepared in step 2) are uniformly mixed at a mass ratio of 1:400. The mixture is ultrasonically treated at 10°C for 30 min with an ultrasonic power of 480W. The COF / ionic liquid composite solution is then deposited on the PVDF membrane using a vacuum-assisted method (vacuum degree of 0.1 MPa).

[0063] Testing showed that the COF nanosheet confined ionic liquid gas sensing membrane material prepared by the above method exhibited strong sensing performance for acetone, with a response rate of 82% to 200 ppm acetone (e.g., ...). Figure 6 As shown in the figure, the sensing membrane exhibits good stability and repeatability, and can achieve multiple cycle tests. Example 6 The preparation method of a COF nanosheet confined ionic liquid in this embodiment includes the following steps: 1) The preparation method of COF nanosheets in this embodiment is the same as that in Example 1.

[0064] 2) Preparation of ionic liquid solution: Add 1 g of [EMIM][OAc] ionic liquid to 10 ml of ethanol solvent and stir until well mixed.

[0065] 3) The COF nanosheet solution prepared in step 1) and the ionic liquid solution prepared in step 2) are uniformly mixed at a mass ratio of 1:400. The mixture is ultrasonically treated at 0℃ for 10 min with an ultrasonic power of 480W. The COF / ionic liquid composite solution is deposited on the PVDF film using a vacuum-assisted method (vacuum degree of 0.1MPa).

[0066] Tests showed that the COF nanosheet confined ionic liquid gas sensing membrane material prepared by the above method has strong sensing performance for acetone and can achieve multiple cycle tests.

[0067] Example 7 The preparation method of a COF nanosheet confined ionic liquid in this embodiment includes the following steps: 1) The preparation method of COF nanosheets in this embodiment is the same as that in Example 1.

[0068] 2) Preparation of ionic liquid solution: Add 1 g of [BMIM][BF4] ionic liquid to 5 ml of dimethyl sulfoxide solvent and stir until well mixed.

[0069] 3) The COF nanosheet solution prepared in step 1) and the ionic liquid solution prepared in step 2) are uniformly mixed at a mass ratio of 1:400. The mixture is ultrasonically treated at 15°C for 10 min with an ultrasonic power of 720W. The COF / ionic liquid composite solution is then deposited on the PVDF membrane using a vacuum-assisted method (vacuum degree of 0.1 MPa).

[0070] Tests showed that the COF nanosheet confined ionic liquid gas sensing membrane material prepared by the above method has strong sensing performance for acetone and can achieve multiple cycle tests.

[0071] Example 8 The preparation method of a COF nanosheet confined ionic liquid in this embodiment includes the following steps: 1) The preparation method of COF nanosheets in this embodiment is the same as that in Example 1.

[0072] 2) Preparation of ionic liquid solution: Add 0.5 g of [BMIM][TFSI] ionic liquid to 10 ml of ethanol solvent and stir until well mixed.

[0073] 3) The COF nanosheet solution prepared in step 1) and the ionic liquid solution prepared in step 2) are uniformly mixed at a mass ratio of 1:100. The mixture is then ultrasonically treated at -5℃ for 1 h with an ultrasonic power of 120 W. The COF / ionic liquid composite solution is deposited on the PVDF film using a vacuum-assisted method (vacuum degree of 0.08MPa).

[0074] Tests showed that the COF nanosheet confined ionic liquid gas sensing membrane material prepared by the above method can also detect acetone gas, exhibiting a 32.6% response to 50 ppm acetone, and maintaining a stable response for 6 cycles. Figure 7 (As shown).

[0075] Example 9 The preparation method of a COF nanosheet confined ionic liquid in this embodiment includes the following steps: 1) The preparation method of COF nanosheets in this embodiment is the same as that in Example 1.

[0076] 2) Preparation of ionic liquid solution: Add 1 g of [BMIM][TFSI] ionic liquid to 10 ml of ethanol solvent and stir until well mixed.

[0077] 3) The COF nanosheet solution prepared in step 1) and the ionic liquid solution prepared in step 2) are uniformly mixed at a mass ratio of 1:1000. The mixture is ultrasonically treated at -5℃ for 1 h with an ultrasonic power of 120 W. The COF / ionic liquid composite solution is deposited on the PVDF film using a vacuum-assisted method (vacuum degree of 0.08 MPa).

[0078] Tests showed that the COF nanosheet confined ionic liquid gas sensing membrane material prepared by the above method can also detect acetone gas, with a response rate of 28.5% to 50 ppm acetone, and can respond stably for 6 cycles.

[0079] Comparative Example 1 1) The preparation method of COF nanosheets in this comparative example is the same as that in Example 1.

[0080] 2) Preparation of ionic liquid solution: Add 0.2 g of [BMIM][TFSI] ionic liquid to 10 ml of ethanol solvent and stir until well mixed.

[0081] 3) The COF nanosheet solution prepared in step 1) and the ionic liquid solution prepared in step 2) are uniformly mixed at a mass ratio of 1:40. The mixture is ultrasonically treated with a power of 360W for 10 min. The COF / ionic liquid composite solution is then deposited on the PVDF film using a vacuum-assisted method.

[0082] The COF nanosheet-confined ionic liquid gas sensing membrane material prepared by the above method exhibits significant fluctuations in its current signal and high background noise, resulting in insufficient signal stability. Although the material shows some sensing response to 100 ppm acetone gas, its cycling stability is poor, maintaining effective detection for only three cycles (e.g., Figure 8 (As shown).

[0083] Comparative Example 2 1) The preparation method of COF nanosheets in this comparative example is the same as that in Example 1.

[0084] 2) Preparation of ionic liquid solution: Add 4 g of [BMIM][TFSI] ionic liquid to 10 ml of ethanol solvent and stir until well mixed.

[0085] 3) The COF nanosheet solution prepared in step 1) and the ionic liquid solution prepared in step 2) are uniformly mixed at a mass ratio of 1:2000. The mixture is ultrasonically treated with a power of 360W for 30 min. The COF / ionic liquid composite solution is then deposited on the PVDF membrane using a vacuum-assisted method.

[0086] After testing, the COF nanosheet confined ionic liquid gas sensing membrane material prepared by the above method showed low sensing response to 100 ppm acetone gas, and the material's response fluctuated greatly in multiple cycle tests, exhibiting poor cycle stability (e.g., Figure 9 (As shown).

[0087] Comparative Example 3 1) Add 5 mg of carbon black to 10 ml of anhydrous ethanol and sonicate at 720 W for 1 h.

[0088] 2) Preparation of ionic liquid solution: Add 1 g of [BMIM][TFSI] ionic liquid to 10 ml of ethanol solvent and stir until well mixed.

[0089] 3) The carbon black solution prepared in step 1) and the ionic liquid solution prepared in step 2) are mixed uniformly at a mass ratio of 1:200. The mixture is ultrasonically treated for 10 min. The COF / ionic liquid composite solution is then deposited on the PVDF membrane using a vacuum-assisted method.

[0090] Testing revealed that the current signal of the carbon black composite ionic liquid membrane material prepared by the above method exhibited particularly significant fluctuations, high background noise, and no response to 1000 ppm acetone gas (e.g., Figure 10 (As shown).

[0091] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0092] The above embodiments of the present invention do not describe all details exhaustively, nor do they limit the present invention to the embodiments described above. Various changes, modifications, substitutions, and variations made by those skilled in the art to these embodiments without departing from the principles and spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A two-dimensional material confined ionic liquid composite membrane, characterized in that, It includes two-dimensional materials and ionic liquids, wherein the ionic liquids are confined within the interlayers and / or channels of the two-dimensional materials.

2. The two-dimensional material confined ionic liquid composite membrane according to claim 1, characterized in that: The two-dimensional material includes any one or a combination of two or more of metal-organic frameworks, covalent organic frameworks, graphene, and transition metal dichalcogenides; and / or, the two-dimensional material includes two-dimensional material nanosheets; Preferably, the specific surface area of ​​the two-dimensional material is 50~7000 m². 2 / g, the porosity of the two-dimensional material is >10%; Preferably, the pore size of the two-dimensional material is 0.1~20nm.

3. The two-dimensional material confined ionic liquid composite membrane according to claim 1, characterized in that: The ionic liquid comprises any one or a combination of two or more of the following: 1-butyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoromethanesulfonylimide, 1-ethyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-1-methylpiperidine bis(trifluoromethanesulfonyl)imide.

4. The two-dimensional material confined ionic liquid composite membrane according to claim 1, characterized in that: The mass ratio of the two-dimensional material to the ionic liquid is 1:100 to 1000; And / or, the thickness of the two-dimensional material confined ionic liquid composite film is 0.5 μm to 20 μm.

5. The method for preparing a two-dimensional material-confined ionic liquid composite film as described in any one of claims 1-4, characterized in that, include: Two-dimensional materials and ionic liquids are combined and self-assembled to prepare a two-dimensional material confined ionic liquid composite membrane.

6. The preparation method according to claim 5, characterized in that, include: The two-dimensional material is mixed uniformly with a first solvent to obtain a two-dimensional material nanosheet solution; preferably, the first solvent includes any one or a combination of two or more of acetone, ethanol and water.

7. The preparation method according to claim 6, characterized in that, include: The ionic liquid is mixed uniformly with the second solvent to obtain an ionic liquid dispersion; preferably, the second solvent includes any one or a combination of two or more of water, methanol, ethanol, dimethyl sulfoxide, dimethylformamide, ethylene glycol, toluene, dichloromethane, chloroform, and n-hexane.

8. The preparation method according to claim 7, characterized in that, include: The two-dimensional material nanosheet solution and ionic liquid dispersion were composited by low-temperature ultrasonication and then deposited on a porous membrane by vacuum-assisted self-assembly to obtain the two-dimensional material confined ionic liquid composite membrane. Preferably, the process conditions for the low-temperature ultrasonic composite include: a temperature of -5 to 15°C, an ultrasonic power of 120W to 720W, and an ultrasonic time of 10 min to 1 h. Preferably, the vacuum degree is 0.08 MPa to 0.1 MPa when performing vacuum-assisted self-assembly.

9. The application of the two-dimensional material confined ionic liquid composite membrane according to any one of claims 1-4 in the preparation of gas sensors.

10. A gas sensor, comprising a gas sensing membrane, characterized in that: The gas sensing membrane comprises a two-dimensional material confined ionic liquid composite membrane as described in any one of claims 1-4.

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