A high proton conductivity membrane based on partially coated montmorillonite with polydopamine and its preparation method

Abstract

The present invention discloses a high proton conductivity membrane based on partially coated montmorillonite of polydopamine and a preparation method thereof, wherein the MMT powder raw material is heat-treated to obtain an MMT sample; the MMT sample is mixed with ultrapure water, stirred at high speed until the MMT sample is fully rehydrated, and then ultrasonically treated to obtain an MMT nanosheet dispersion with a uniform size; DA powder is added to the MMT nanosheet dispersion, and a DA and MMT dispersion system is obtained by sufficient stirring; the pH value of the DA and MMT dispersion system is adjusted to 8.5-9, and a dark brown PDA-MMT nanosheet dispersion is obtained after sufficient stirring; the dark brown PDA-MMT nanosheet dispersion is vacuum filtered, rinsed with ultrapure water, and naturally dried to obtain a PDA-MMT film. The present invention is based on the good adhesion effect of PDA, improves the aqueous phase stability of the non-toxic, mineral-rich and low-cost MMT film, and retains the high proton conductivity of the original MMT film to the maximum extent, as the core material for further production of PEM, greatly reducing the production cost required for PEM.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a high proton conductivity membrane based on partially coated montmorillonite with polydopamine and a preparation method thereof. Background Art

[0002] As a "hydrogen-to-electricity" conversion device on the "hydrogen-using" side, the independent research and development of the key components of the proton exchange membrane fuel cell (PEMFC) (including bipolar plates, gas diffusion layers, catalysts and proton exchange membranes) is a fundamental solution to breaking through the patent restrictions of hydrogen energy in Europe, the United States, Japan and other countries.

[0003] As the core component of PEMFCs, the proton exchange membrane (PEM) must possess high proton conductivity, low fuel permeability, and excellent thermal and chemical stability. Currently, commercial PEM systems primarily utilize perfluorosulfonic acid (PFSA) polymer structures, exemplified by Nafion, manufactured by Dupont Corporation in the United States. Its polymer backbone is polytetrafluoroethylene (PTFE). Through a fluorine chemical synthesis process, hydrophilic sulfonic acid groups are grafted onto the PTFE backbone as side chains, resulting in Nafion's excellent proton conductivity, achieving a proton conductivity of ~0.1 S / cm at room temperature.

[0004] In recent years, research on PEMs has continued unabated. In the area of ​​PFSA-based PEMs, researchers have achieved improvements in specific PEM properties through chemical modification, polymer blending, and nanodoping. Beyond fluorine chemistry, sulfonated hydrocarbon polymers have become an important tool for achieving high-proton-conducting PEMs, and related research has provided multiple options for the continued development of PEMs.

[0005] However, for the PEMs mentioned above, which are more commonly used, although the increase in the number of sulfonic acid groups / high sulfonation in the internal structure of the polymer can improve the proton conductivity of the membrane, it will inevitably cause the PEM to absorb too much water, thereby triggering the gradual separation of the hydrophilic and hydrophobic phases inside the PEM, reducing the dimensional stability and mechanical properties of the membrane, and ultimately causing the degradation of the membrane structure. At the same time, because commercial PEMs are monopolized by countries such as Europe, the United States, and Japan, and involve expensive and highly toxic perfluorinated preparation technology, my country currently faces high cost issues in areas where PEMs are needed. Faced with such difficulties, the key to achieving further widespread application of PEMFCs is to develop low-cost, water-stable PEMs with high proton conductivity through research and development. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a high proton conductivity membrane based on partially coated montmorillonite with polydopamine and a preparation method thereof, so as to solve the technical problems of foreign monopoly of proton exchange membranes, high costs, and poor membrane stability under fluorine-containing and high humidity conditions.

[0007] The present invention adopts the following technical solutions:

[0008] A method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine, comprising the following steps:

[0009] S1, taking MMT powder raw material and performing heat treatment to obtain MMT sample;

[0010] S2, mixing the MMT sample after the heat treatment in step S1 with ultrapure water, stirring at high speed until the MMT sample is fully rehydrated, and then ultrasonically treating to obtain a dispersion of MMT nanosheets with uniform size;

[0011] S3, adding DA powder to the MMT nanosheet dispersion obtained in step S2, and stirring thoroughly to obtain a DA and MMT dispersion system;

[0012] S4, adjusting the pH value of the DA and MMT dispersion system obtained in step S3 to 8.5-9, and obtaining a dark brown PDA-MMT nanosheet dispersion after sufficient stirring;

[0013] S5. The dark brown PDA-MMT nanosheet dispersion obtained in step S4 is vacuum filtered, rinsed with ultrapure water, and then naturally dried to obtain a PDA-MMT film.

[0014] Preferably, step S1 is specifically:

[0015] The heating rate was set to 10°C / min, and the MMT powder raw material was heated at 150±5°C for 5 to 10 minutes, and then naturally cooled to perform partial dehydration of the MMT powder.

[0016] Preferably, in step S2, the mass volume ratio of the MMT sample to ultrapure water is (0.029-0.031) g:300 mL, the stirring time is 6-8 h, the ultrasonic treatment time is 30-35 min, and the ultrasonic power is 60-80 W.

[0017] Preferably, the concentration of the MMT nanosheet dispersion is 0.97 to 1.03×10 -1 g / L.

[0018] Preferably, in step S3, the mass ratio of DA powder to MMT powder is (0.6-1):1.

[0019] Preferably, the stirring time is 4 to 5 hours.

[0020] Preferably, in step S4, the stirring time is 2 to 2.5 hours to achieve self-polymerization of DA on the surface of the MMT nanosheets, so that PDA is partially coated on the surface of the MMT nanosheets to obtain PDA-MMT nanosheets.

[0021] Preferably, 20 to 25 drops of Tris-HCl buffer are added to adjust the pH value of the DA and MMT dispersion system.

[0022] Preferably, in step S5, the vacuum filtration time is 14 to 16 hours.

[0023] Another technical solution of the present invention is a high proton conductivity membrane based on partially coated montmorillonite with polydopamine, which has a conductivity of 0.4 to 0.6 S cm at room temperature. -1 along-surface proton conductivity.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] A method for preparing a high-proton conductivity membrane based on partially coated montmorillonite with polydopamine. A PDA-MMT membrane structure with high proton conductivity is developed based on the non-toxic, mineral-rich and low-cost two-dimensional (2D) montmorillonite (MMT) material, which greatly reduces the production cost of further PEM. At the same time, the PDA-MMT membrane improves the aqueous phase stability of the 2D MMT stacked structure film by partially coating it with polydopamine (PDA). If used as the main component of a new PEM, it can effectively improve the swelling resistance of the PEM.

[0026] Furthermore, heating the MMT powder to a specific temperature can achieve a "starvation treatment" effect, partially dehydrating the MMT powder, thereby enhancing its own hydrophilicity and facilitating its subsequent full rehydration.

[0027] Furthermore, for 10 -1 High-speed stirring of MMT dispersion near the concentration of 0.5 g / L for 6 to 8 hours is conducive to the full dispersion and rehydration process of MMT, and the expansion of the MMT interlayer spacing. Assisted by 30 to 35 minutes of low-power weak ultrasonic action of 60 to 80 W, the MMT layered structure can be promoted to maintain the original aspect ratio while peeling off, thereby obtaining uniformly dispersed MMT nanosheets.

[0028] Furthermore, DA is easily soluble in water and has an adhesive effect. After sufficient stirring, DA can be fully adsorbed on the surface of MMT nanosheets, providing the prerequisite for their subsequent surface self-polymerization into PDA. Experiments have shown that a DA&MMT mass ratio of 0.6:1 to 1:1 can directly lead to the subsequent PDA-MMT film having good aqueous phase stability.

[0029] Furthermore, the weakly alkaline pH environment can promote the self-polymerization of DA adsorbed on the surface of MMT nanosheets into PDA. After 2 to 2.5 hours of stirring self-polymerization process, DA can be fully converted into PDA and partially coated on the surface of MMT nanosheets to form PDA-MMT nanosheets with good adhesion effect, providing a good premise for further PDA-MMT films.

[0030] Furthermore, the vacuum filtration process can make the PDA-MMT single layer / several layers of nanosheets completely stacked in parallel, realizing the transformation of powdered MMT particles into PDA-MMT films with good aqueous phase stability. Additional ultrapure water can wash away excess small molecules and ions in the PDA-MMT film, obtaining a PDA-MMT film with higher purity.

[0031] The PDA-MMT film developed by the present invention achieves a thermal conductivity of 0.6S cm at room temperature. -1 The surface proton conductivity is higher than that of Nafion membranes of the same thickness, and the performance remains stable for 1 month.

[0032] In summary, the present invention improves the aqueous phase stability of the non-toxic, mineral-rich and low-cost MMT film based on the good adhesion effect of PDA, and maximizes the retention of the original high proton conductivity of the MMT film. As the core material for the further production of PEM, it greatly reduces the production cost required for PEM.

[0033] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Characterization diagrams of MMT and its exfoliated nanosheets, where (a) is the MMT powder morphology, (b) is the XRD pattern; (c) is the single-layer / few-layer distribution of MMT exfoliated nanosheets under TEM; (d) is the SAED pattern of MMT exfoliated nanosheets;

[0035] Figure 2 Characterization diagrams of flexible 2D MMT stacked structure films, where (a) is a 4 cm diameter flexible MMT film, (b) is a cross-sectional SEM image, and (c) is the EDS element distribution on the film surface.

[0036] Figure 3Figure 3 is a graph showing the characterization and performance curves of the MMT film proton conductivity test, where (a) is a SEM photo of a cross-section of MMT films of different thicknesses; (b) is a sample of MMT rectangular films of different sizes and thicknesses used for packaging testing; (c) is a typical PDMS-encapsulated 2D nanofluidic device used to test the proton conductivity of the MMT film along the surface; (d) is a schematic diagram of the test platform; (e) is a curve showing the change of the ionic conductivity along the surface of the MMT film with time in a pure water electrolyte; (f) is the corresponding IV curve of the proton conductivity test along the surface of different MMT film samples in a 1M HCl electrolyte solution;

[0037] Figure 4 Figure 2 shows the characterization test of unstable MMT films in aqueous phase and the significant decrease in proton conductivity performance. (a) shows rectangular MMT films of different thicknesses; (b) shows an MMT film that was damaged by a slight lift after being treated in water for 20 seconds; (c) shows a 2D nanofluidic device encapsulating a damaged MMT film sample; (d) shows the corresponding IV curve of the along-surface proton conductivity test of the damaged MMT film sample in 1M HCl electrolyte solution; (e) shows the comparison of along-surface proton conductivity of a normal MMT film sample and a damaged MMT film sample in 1M HCl electrolyte solution.

[0038] Figure 5 Figure 3 is a simulation result diagram of the formation of various configurations in MMT by the introduction of PDA, among which (a) is a screenshot of four DA monomers stably adsorbed on the surface of MMT monolayer in water environment in NVT model; (b) is the PDA structure used for simulation; (c) is the configuration containing one layer of PDA between MMT layers (most stable), and (d) is the configuration containing two layers of PDA between MMT layers; (e)-(g) are the swelling free energies of PDA-MMT systems predicted by multi-dimensional dynamics simulation (the dotted lines in each figure show the interlayer spacing corresponding to different numbers of PDA layers, and the insets are screenshots of various configurations in the metadynamics simulation system);

[0039] Figure 6 The distance diagram of the characteristic atoms of dopamine monomer (DA) in the aqueous environment and the MMT surface during the last 5 ns of the simulation, where (a)-(d) are the distances of three typical atoms (one amino nitrogen atom N and two hydroxyl oxygen atoms O) in each DA monomer during the last 5 ns. 1 , O 2 ) and the surface distance of MMT nanosheets;

[0040] Figure 7 The interlayer water H, O atoms and interlayer Na atoms when PDA is present between MMT layers during the simulation + Density distribution diagram of the interlayer H, O atoms and Na when there is only one layer of water between the MMT layers. + (b) is the density distribution of H, O atoms and Na when there are only two layers of water between the MMT layers.+ The density distribution of H, O atoms and Na atoms between the MMT layers is shown in Figure 2. (c) The density distribution of H, O atoms and Na atoms between the MMT layers is shown in Figure 2. + The density distribution of H, O atoms and Na when the MMT layer contains two layers of PDA + density distribution;

[0041] Figure 8 Flow chart for the preparation of PDA-MMT films;

[0042] Figure 9 The morphologies of PDA-MMT films with different DA to MMT mass ratios and different thicknesses are shown, where (a) is 0.1DA-MMT film, (b) is 0.2DA-MMT film, (c) is 0.4DA-MMT film, (d) is 0.6DA-MMT film, (e) is 0.8DA-MMT film, and (e) is 1DA-MMT film;

[0043] Figure 10 The graph shows the experimental results of the aqueous phase stability of PDA-MMT films with different DA to MMT mass ratios;

[0044] Figure 11 Figures illustrating the xDA-MMT nanosheet precursor and TEM-related characterizations, where (a) is the Tyndall effect of the original MMT nanosheet dispersion and the precursor nanosheet dispersion corresponding to the aqueous phase-stabilized PDA-MMT film; (b) is the HAADF image of the 0.6DA-MMT nanosheet, and (c) is the EDS analysis of the 0.6DA-MMT nanosheet; (d) is the HAADF image of the 0.8DA-MMT nanosheet, and (e) is the EDS analysis of the 0.8DA-MMT nanosheet; (f) is the HAADF image of the 1DA-MMT nanosheet, and (g) is the EDS analysis of the 1DA-MMT nanosheet; (h) is the SAED diffraction pattern corresponding to 0.6DA-MMT, (i) is the SAED diffraction pattern corresponding to 0.8DA-MMT, and (j) is the SAED diffraction pattern corresponding to 1DA-MMT nanosheet;

[0045] Figure 12 Figures illustrating the characterization of xDA-MMT nanosheets, where (a) is the SEM image of the original MMT nanosheet obtained by peeling, (b) is the SEM image of the 0.6DA-MMT nanosheet, (c) is the SEM image of the 0.8DA-MMT nanosheet, and (d) is the SEM image of the 1DA-MMT nanosheet; (e) is the TEM image of the PDA-MMT nanosheet and the surface of the MMT crystal layer structure after filtering and noise reduction (the inset is the theoretical surface atomic layer of the MMT crystal layer);

[0046] Figure 13Figure 3 is a characterization diagram of xDA-MMT film, where (a) is a cross-sectional view of the PDA-MMT film, (b) is the distribution of N elements in the yellow box area of ​​(a); (c) is the FT-IR spectrum of the MMT film and the xDA-MMT film; (d) is the XRD spectrum of the MMT film and the xDA-MMT film in the original state, after heating and after hydration; (e) is the change of the water contact angle of the MMT film and the xDA-MMT film;

[0047] Figure 14 The data of the proton transport performance of xDA-MMT film are shown in Figure 2, where (a) is the ToF-SIMS analysis of the Na content of xDA-MMT film before and after proton exchange. + / Si + Relative intensity change; (b) 0.6DA-MMT rectangular film samples of different sizes used for packaging testing; (c) Schematic diagram of the test platform for the proton conductivity along the surface of the xDA-MMT film; (d) IV curves of the 0.6DA-MMT film after stabilization under different acid electrolyte concentrations; (e) Proton conductivity along the surface of the xDA-MMT film after stabilization under different acid electrolyte concentrations; (f) Proton conductivity durability test results of the xDA-MMT film and Nafion NR211 film;

[0048] Figure 15 Figures showing supplementary data related to the proton transport performance of xDA-MMT films, where (a) is the Zeta potential distribution of xDA-MMT nanosheets; (b) is the 0.8DA-MMT rectangular film samples of different sizes used for packaging tests; (c) is the 1DA-MMT rectangular film samples of different sizes used for packaging tests; (d) is the IV curve of the 0.8DA-MMT film after stabilization at different acid electrolyte concentrations; (e) is the IV curve of the 1DA-MMT film after stabilization at different acid electrolyte concentrations; (f) is the IV curve obtained by the drift-diffusion experiment with asymmetric concentration acid electrolyte solutions loaded on both sides of the xDA-MMT film (the inset is a schematic diagram of the drift-diffusion experiment principle). DETAILED DESCRIPTION

[0049] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0050] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0051] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0052] In the present invention, unless otherwise specified, percentages (%) or parts refer to percentages by weight or parts by weight relative to the composition.

[0053] In the present invention, unless otherwise specified, the components involved or their preferred components can be combined with each other to form a new technical solution.

[0054] In this disclosure, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6-22" indicates that all real numbers between "6-22" are listed herein, and "6-22" is merely an abbreviation for these numerical combinations.

[0055] The "range" disclosed in the present invention is in the form of lower limit and upper limit, which can be one or more lower limits, and one or more upper limits respectively.

[0056] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0057] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the order. Preferably, the reaction method herein is carried out sequentially.

[0058] Unless otherwise indicated, the professional and scientific terms used herein are the same as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0059] The microstructured, two-dimensional (MMT) clay mineral is a typical, abundant, low-cost, chemically and thermally stable, and environmentally friendly clay mineral. It consists of two silicon-oxygen tetrahedral sheets and one aluminum-oxygen octahedral sheet. Frequent isomorphous substitution endows MMT with excellent adsorption, cation exchange, and swelling properties. Previously, MMT was used as just one of several inorganic nanofillers in organic PEMs for proton conduction. However, exfoliated MMT nanosheets can be readily reassembled into stacked thin films by vacuum filtration, resulting in continuous interstitial spaces with tunable interlayer spacing. Furthermore, MMT possesses excellent water-retention and acid-binding properties, suggesting its potential as a next-generation PEM using inorganic structures as proton transport media. Self-assembled layered membranes from exfoliated vermiculite nanosheets have been reported to possess the ability to construct 2D nanofluidic proton channels with excellent proton conductivity. However, the use of 2D nanochannel arrays formed by MMT nanosheets as the main proton transport medium has not yet received attention. The main reason may be that the swelling rate of the intrinsic MMT membrane in an aqueous environment is too large, which inevitably leads to a decrease in aqueous phase stability and loss of molecular selectivity. If the interlayer spacing of the layered MMT film is further restricted to a certain extent through molecular intercalation or pillaring processes, rapid proton conduction can be achieved using 2D MMT nanochannel arrays.

[0060] See also Figure 8 The present invention provides a method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine, comprising the following steps:

[0061] S1. Place the MMT powder raw material in a clean crucible and transfer it to a muffle furnace. Set the heating rate to 10°C / min, heat the sample at 150±5°C for 5-10 minutes, and then cool it naturally to partially dehydrate the MMT powder.

[0062] S2. The heat-treated MMT sample was mixed with ultrapure water at a mass volume ratio of (0.029-0.031) g: 300 mL, and stirred at room temperature for 6-8 h at high speed to ensure that the heat-treated MMT sample was fully rehydrated. Then, the MMT was fully exfoliated by ultrasonication at a power of 60-80 W for 30-35 min, thereby obtaining a dispersion of MMT nanosheets with uniform size. The concentration of the MMT nanosheet dispersion was 0.97-1.03×10 -1 g / L;

[0063] MMT is divided into multiple categories according to the different types of interlayer cations. The sodium-based MMT used in this invention has a good exfoliation effect and is a white powder solid morphology. Figure 1 (a) is shown. Its XRD pattern is as follows Figure 1As shown in (b), the typical 1.24nm interlayer spacing of sodium-based MMT and the XRD related peaks corresponding to different crystal planes are reflected. Referring to relevant literature, the present invention first realized the low-cost "heat treatment / rehydration + micro-ultrasound" liquid phase exfoliation of MMT. The TEM morphology of the MMT nanosheets obtained after exfoliation is as follows Figure 1 As shown in (c), the sizes are all in the hundreds of nanometers and are evenly distributed. The selected area electron diffraction (SAED) pattern of the MMT nanosheets is shown in Figure 1 As shown in (d), the SAED shows clear and regular diffraction spots, and the obtained interplanar spacing also corresponds well with the XRD pattern (for example, the innermost circle of diffraction spots corresponds to the 100-plane, and the interplanar spacing is 0.46nm, which corresponds well to the diffraction peak at 19.8° in the XRD pattern). After the MMT stripping is completed, the MMT nanosheet dispersion is vacuum filtered to obtain a flexible 2D stacked structure MMT film that can be bent 180° in both directions, as shown in FIG. Figure 2 (a). Its cross-sectional structure shows that the MMT film has a good micro-layered structure ( Figure 2 (b)), EDS element analysis also shows the various characteristic elements of MMT in MMT film, such as Figure 2 (c) shown.

[0064] S3, adding DA powder with a certain mass ratio to MMT into the prepared MMT nanosheet dispersion, and stirring thoroughly for 4 to 5 hours to achieve the adsorption of DA on the surface of MMT nanosheets;

[0065] The mass ratio of DA powder and MMT nanosheet dispersion is (0.6~1):1.

[0066] S4, adding 20 to 25 drops of Tris-HCl buffer to the DA and MMT dispersion system, adjusting the pH value of the dispersion to 8.5 to 9, and stirring thoroughly for 2 to 2.5 hours to achieve self-polymerization of DA on the surface of the MMT nanosheets, so that PDA is partially coated on the surface of the MMT nanosheets to obtain a PDA-MMT nanosheet dispersion;

[0067] S5. The PDA-MMT nanosheet dispersion that has turned dark brown is vacuum filtered for 14 to 16 hours to promote the self-assembly film formation process of the PDA-MMT nanosheets, and ultrapure water is used to clean the excess ions and molecules in the wet film. After natural drying, the PDA-MMT film is obtained.

[0068] The high proton conductivity membrane based on partially coated montmorillonite with polydopamine prepared by the method of the present invention can exist stably in the aqueous phase and has a conductivity of 0.4 to 0.6 S cm at room temperature. -1 The surface proton conductivity is tested and maintained for at least 1 month.

[0069] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0070] Example 1

[0071] S1. Place the MMT powder raw material in a clean crucible and transfer it to a muffle furnace. Set the heating rate to 10°C / min, heat the sample at 150°C for 5 minutes, and then cool it naturally to partially dehydrate it.

[0072] S2, the heat-treated MMT sample was mixed with ultrapure water in a certain ratio (0.03 g: 300 mL, concentration of 1.0 × 10 -1 g / L) were mixed and stirred at high speed at room temperature for 6 h to ensure that the heat-treated MMT sample was fully rehydrated, and then ultrasonicated at 60 W ultrasonic power for 30 min to promote the full exfoliation of MMT, thereby obtaining a dispersion of MMT nanosheets with uniform size;

[0073] S3, taking DA powder and adding it to the prepared MMT nanosheet dispersion, the mass ratio of DA powder to MMT nanosheet dispersion is 0.6:1, and stirring thoroughly for 4 hours to achieve the adsorption of DA on the surface of MMT nanosheets;

[0074] S4, adding 20 drops of Tris-HCl buffer to the DA and MMT dispersion system, adjusting the pH value of the dispersion to 8.5, and stirring thoroughly for 2 hours to achieve self-polymerization of DA on the surface of the MMT nanosheets, so that PDA is partially coated on the surface of the MMT nanosheets to obtain PDA-MMT nanosheets;

[0075] S5. The dark brown PDA-MMT nanosheet dispersion was vacuum filtered for 15 h to promote the self-assembly film formation process of the PDA-MMT nanosheets. The excess ions and molecules of the wet film were washed with ultrapure water. After natural drying, the PDA-MMT film was obtained. The experimental test showed that the PDA-MMT film had a thermal conductivity of 0.6 S cm at room temperature. -1 along-surface proton conductivity.

[0076] Example 2

[0077] S1. Place the MMT powder raw material in a clean crucible and transfer it to a muffle furnace. Set the heating rate to 10°C / min. Heat the sample at 155°C for 7 minutes and then cool it naturally to partially dehydrate it.

[0078] S2, the heat-treated MMT sample was mixed with ultrapure water in a certain ratio (0.031 g: 300 mL, concentration of 1.03 × 10 - 1 g / L) were mixed and stirred at high speed at room temperature for 8 h to ensure that the heat-treated MMT sample was fully rehydrated, and then ultrasonicated at 80 W ultrasonic power for 35 min to promote the full exfoliation of MMT, thereby obtaining a dispersion of MMT nanosheets with uniform size;

[0079] S3, taking DA powder and adding it to the prepared MMT nanosheet dispersion, with the mass ratio of DA powder to MMT nanosheet dispersion being 1:1, and stirring thoroughly for 5 h to achieve the adsorption of DA on the surface of MMT nanosheets;

[0080] S4, adding 25 drops of Tris-HCl buffer to the DA and MMT dispersion system, adjusting the pH value of the dispersion to 9, and stirring thoroughly for 2.3 hours to achieve self-polymerization of DA on the surface of the MMT nanosheets, so that PDA is partially coated on the surface of the MMT nanosheets to obtain PDA-MMT nanosheets;

[0081] S5. The PDA-MMT nanosheet dispersion that has turned dark brown is vacuum filtered for 14 hours to promote the self-assembly film formation process of the PDA-MMT nanosheets, and ultrapure water is used to clean the excess ions and molecules in the wet film. After natural drying, the PDA-MMT film is obtained.

[0082] Example 3

[0083] S1. Place the MMT powder raw material in a clean crucible and transfer it to a muffle furnace. Set the heating rate to 10°C / min. Heat the sample at 145°C for 10 minutes and then cool it naturally to partially dehydrate it.

[0084] S2, the heat-treated MMT sample was mixed with ultrapure water in a certain ratio (0.029 g: 300 mL, concentration 0.97 × 10 - 1 g / L) were mixed and stirred at high speed at room temperature for 7 h to ensure that the heat-treated MMT sample was fully rehydrated, and then ultrasonicated at 70 W ultrasonic power for 32 min to fully exfoliate the MMT, thereby obtaining a dispersion of MMT nanosheets with uniform size;

[0085] S3, taking DA powder and adding it to the prepared MMT nanosheet dispersion, the mass ratio of DA powder to MMT nanosheet dispersion is 0.8:1, and stirring thoroughly for 4.5 hours to achieve the adsorption of DA on the surface of MMT nanosheets;

[0086] S4, adding 23 drops of Tris-HCl buffer to the DA and MMT dispersion system, adjusting the pH value of the dispersion to 8.8, and stirring thoroughly for 2.5 hours to achieve self-polymerization of DA on the surface of the MMT nanosheets, so that PDA is partially coated on the surface of the MMT nanosheets to obtain PDA-MMT nanosheets;

[0087] S5. The PDA-MMT nanosheet dispersion that has turned dark brown is vacuum filtered for 16 hours to promote the self-assembly film formation process of the PDA-MMT nanosheets, and ultrapure water is used to clean the excess ions and molecules in the wet film. After natural drying, the PDA-MMT film is obtained.

[0088] After the MMT stripping is completed, the MMT nanosheet dispersion is vacuum filtered to obtain a flexible 2D stacked structure MMT film that can be bent 180° in both directions. Figure 2 (a). Its cross-sectional structure shows that the MMT film has a good micro-layered structure ( Figure 2 (b)), EDS element analysis also shows the various characteristic elements of MMT in MMT film, such as Figure 2 (c) shown.

[0089] The proton conductivity of the MMT film was tested through experiments. Figure 3 As shown in (a), layered MMT films of different thicknesses were first prepared. Based on this, three rectangular MMT film samples (s1, s2, and s3) with different dimensions (length, width, and thickness) were cut out and encapsulated into 2D nanofluidic devices using polydimethylsiloxane (PDMS) for further along-plane proton conductivity testing, as shown in Figure 2. Figure 3 (b)-(d) As shown in the experiment, when ultrapure water is used as the electrolyte, it takes about 6 hours to observe that the ionic conductivity is stable at 2.29μS. Figure 3 (e) After the three membrane samples were immersed in 1M HCl electrolyte for 24 hours, their surface proton conductivity (σ) was measured, and the relevant IV curves are shown in Figure 3 (f) As shown. After testing, the σ values ​​of s1, s2 and s3 are 1.36S cm -1 、1.29S cm -1 and 1.01S cm -1 , with an average value of 1.22S cm -1 , which also proves that the MMT film has ultra-high surface proton conductivity.

[0090] However, after σ measurement, it was found that the edge area of ​​the encapsulated MMT membrane sample in contact with the aqueous electrolyte was partially dissolved into a muddy state. After the aqueous phase stability test of the MMT membrane, the results showed that MMT membranes of different thicknesses could not exist stably in an aqueous environment. The excessive swelling of MMT would lead to its poor mechanical integrity, such as Figure 4 (a), (b). In addition, there are two damaged MMT film samples (ds1 and ds2, Figure 4 (c)) σ measurements were performed on the 2D nanofluidic device (the membrane edge was also partially dissolved, and more seriously, the interior was damaged), and the IV curves were recorded, as shown in Figure 4 As shown in (d), the σ values ​​of ds1 and ds2 are 0.27S cm -1 and 0.32S cm -1 By comparing the average σ values ​​of normal MMT film samples and damaged MMT samples, it was found that the aqueous phase instability of the MMT membrane eventually led to membrane destruction, which in turn caused a sharp drop in proton conductivity, such as Figure 4 (e) shown.

[0091] In summary, the intrinsic MMT film has the ability to achieve fast proton conduction, and the surface proton conductivity σ exceeds 10 0 S cm -1 However, the poor swelling tolerance of MMT membranes will inevitably lead to their own disintegration and a decrease in σ, which would be disastrous if they were directly used as PEM functional units in PEMFCs. If MMT is to be used to realize a new generation of PEMs, using its inorganic structure as a proton transport medium, it is necessary to further modify MMT to improve its aqueous phase stability while maintaining its excellent proton conductivity.

[0092] Previous studies have reported that the introduction of certain rigid aromatic groups into PEM can bring about aqueous phase stability. Inspired by the adhesive proteins secreted by mussels, Lee et al. first discovered that polydopamine (PDA) with good hydrophilicity formed by self-polymerization of dopamine (DA) can adhere to almost all types of material surfaces, including SiO2 crystals, Al2O3, polycarbonate (PC), polytetrafluoroethylene (PTFE), PDMS and polyetheretherketone (PEEK), etc., regardless of their hydrophilicity / hydrophobicity. Due to this unique property, PDA is used in many scenarios, such as hydrogels, metal deposition and energy storage devices. Yoon et al. used PDA as an interfacial glue to achieve strong adhesion between PTFE and PFSA polymers, thereby preparing a highly durable PEM. Therefore, the introduction of PDA is conducive to achieving mechanical stability of the modified object.

[0093] The present invention predicts the effect of the introduction of PDA on MMT through molecular computational simulation analysis. Considering that the actual experiment first involves the process of introducing DA into the MMT nanosheet dispersion, the interaction between DA and MMT monolayer in an aqueous environment was studied for the first time through molecular dynamics (MD) simulation during the research process, that is, a 10ns NVT was performed on a model containing 4 DA monomers and an MMT monolayer. The DA monomer was initially placed at a position far away from the MMT surface. By recording the relative position of the DA monomer and the MMT surface, it was found that the DA monomer gradually approached the MMT surface and showed a stable adsorption effect, such as Figure 5 As shown in (a). Figure 6 The characteristic atoms in the four DA monomers recorded (N atom on the amino group and O atoms on the two hydroxyl groups) 1 , O 2 The distance between the atoms and the MMT surface along the z direction (the direction perpendicular to the surface of the MMT nanosheet) in the last 5 ns of the simulation also confirms this effect. By adjusting the pH, DA can further self-polymerize into PDA, such as Figure 5 (b) In order to characterize the effect of the introduction of PDA on the swelling process of MMT in pure water, a PDA-MMT simulation system was established. By exploring the distribution of PDA between MMT nanosheets through multi-dimensional dynamics simulation, two stable configurations were always found: one with one layer of PDA between the MMT layers and the other with two layers of PDA between the MMT layers, as shown in Figure 2. Figure 5 (c) and (d) are shown. Through multi-dimensional dynamics simulation, the swelling free energy distribution of PDA-MMT system in pure water is shown as follows Figure 5 (e)-(g) show that the global minima in each free energy curve correspond to a configuration with a single PDA layer between the MMT layers. Therefore, the simulations revealed that a single PDA layer between the PDA-MMT layers is the most stable state for the PDA-MMT system.

[0094] In addition, the MD simulation also obtained the interlayer water H, O atoms and interlayer Na atoms in the hydrated state when PDA was present between the MMT layers. + The density distribution of Figure 7 The results show that the addition of PDA has a slight effect on the water density distribution, but has no significant effect on Na + The distribution of Na + The PDA is distributed near the MMT surface and appears to be bound between the PDA and MMT surfaces, which is most likely due to the more stable interaction between PDA and MMT. Metadynamics simulations revealed that the introduction of PDA significantly inhibited the peeling of MMT in the z-direction, which can be attributed to the adhesion effect brought by PDA.

[0095] Table 1 Peeling energy of MMT with or without PDA between layers along different directions

[0096]

[0097] As shown in Table 1, by using stretching molecular dynamics (SMD) in the y (parallel to the MMT surface direction) and z directions for the hydrated MMT configurations with and without PDA in the interlayer, it was further found that the peeling energy of MMT increased significantly with the introduction of PDA, especially in the y direction. Compared with MMT without PDA introduction, the peeling energy of MMT with PDA introduction increased by 6 times.

[0098] In summary, the introduction of PDA can effectively inhibit the disordered swelling process of MMT nanostructures and improve their exfoliation energy. Once the system is expanded to the macroscopic level, the addition of PDA is expected to effectively improve the aqueous stability of MMT films and maintain the proton conductivity of MMT films.

[0099] Through preliminary experiments, it was found that the aqueous phase stability of PDA-MMT films is related to the mass ratio of DA to MMT. Therefore, the present invention first prepared black paper-like PDA-MMT films with different mass ratios of DA to MMT, such as Figure 9 As shown. For easy distinction, the PDA-MMT film is labeled as xDA-MMT, where x represents the mass ratio of DA to MMT (0.1, 0.2, 0.4, 0.6, 0.8, 1). Two samples of different thicknesses were also prepared for each group of xDA-MMT films to simultaneously observe the flexibility changes of the xDA-MMT films. Figure 9 Most xDA-MMT membranes exhibit flexible properties and can be bent 180°, similar to intrinsic MMT films. However, due to the rigidity of the aromatic rings in the PDA structure, the stiffness of the xDA-MMT membranes gradually increases with increasing x values. For thick 1DA-MMT membranes, rigid fracture occurs after bending only about 120°, but this fracture does not affect their performance as proton transport hosts.

[0100] The aqueous stability of xDA-MMT films is Figure 10 As shown. A small rectangular piece is cut out of each film and Figure 10 The aqueous stability test shown is performed by soaking in water for 24 hours before performing the tweezers "lift-and-put-down" operation.

[0101] The results showed that the 0.1DA-MMT and 0.2DA-MMT films disintegrated without any external force after being immersed in water for 24 hours. For the 0.4DA-MMT film, only a small amount of dissolution occurred after 24 hours of water treatment, but it quickly disintegrated when the "lifting" operation was performed. Only when the x value of the xDA-MMT film was greater than or equal to 0.6 could it maintain its own dimensional stability and mechanical integrity under this rigorous testing process. In addition, the 0.6DA-MMT film, the 0.8DA-MMT film, and the 1DA-MMT film remained intact even after being immersed in water for an additional 14 days. Therefore, introducing a certain amount of PDA into the MMT membrane can effectively improve its aqueous phase stability, which is very consistent with the results of the simulation part.

[0102] If we want to realize a new generation of high proton conductivity membranes with inorganic structures as the main proton transport medium, it is crucial to study the nanostructure and proton conductivity of water-stable PDA-MMT membranes. Figure 11 As shown in (a), under a red laser beam, obvious Tyndall effect can be observed in the dark brown 0.6DA-MMT dispersion, 0.8DA-MMT dispersion and 1DA-MMT dispersion, which is the same as the intrinsically exfoliated MMT nanosheet dispersion, indicating that the nanosheets in each dispersion can exist stably in an aqueous environment. Figure 11 (b)-(g) show the high-angle annular dark field (HAADF) images and corresponding EDS spectra of xDA-MMT nanosheets. It can be seen that the N and C elements derived from PDA are concentrated in the brighter areas of the corresponding xDA-MMT nanosheets, which indicates that PDA exists on the surface of MMT nanosheets in the form of partial coating. When the relative mass ratio of DA increases to 0.8 and 1, the PDA coating area on the MMT surface becomes denser, which is undoubtedly the fundamental reason for the aqueous stability of all xDA-MMT membranes. At the same time, Figure 12 As shown in (a)-(d), compared with the uniform dispersion contrast of the intrinsic MMT nanosheets peeled off under SEM, the xDA-MMT nanosheets show increasingly uneven dispersion contrast relative to the substrate under SEM, which further indicates that PDA can adsorb on the surface of MMT nanosheets and agglomerate them, or pull the peeled nanosheets back together. Figure 1 Compared with the SAED pattern of intrinsic MMT nanosheets shown in (d), Figure 11 The SAED spectra shown in (h)-(j) show that as the PDA coating increases, the more amorphous features introduced by PDA gradually cover up the crystalline features of MMT. Nevertheless, the crystal structure of MMT itself is not objectively damaged, it is just because more PDA covers its surface, such as Figure 12As shown in (e), after filtering and noise reduction of the TEM image of PDA-MMT nanosheets, the MMT surface consistent with the theoretical MMT crystal structure is highlighted.

[0103] Similar to the intrinsic MMT film, the self-assembled xDA-MMT film also has an ordered layered microstructure due to the stacking of 2D xDA-MMT nanosheets, such as Figure 13 As shown in (a), Figure 13 (b) The corresponding EDS spectrum also confirms the uniform distribution of PDA throughout the membrane. Figure 13 (c) shows the Fourier transform infrared (FT-IR) spectrum of different films, which shows the wave number distribution of the main vibration modes. -1 and 3550cm -1 The wide band between 3348cm -1 and ~3230cm -1 The peaks at 1200 cm-1 are attributed to the stretching vibrations of N–H and O–H, respectively. -1 and 1800cm -1 A group of peaks related to PDA were also observed, among which 1608 cm -1 and 1471cm -1 The two different peaks at 1508 cm-1 can be attributed to the overlap of C=C resonance vibration and N–H shear vibration in the aromatic ring. -1 and ~1287cm -1 The peaks at 3614 cm-1 are attributed to the symmetrical bending vibration of the N–H bond and the bending vibration of the -OH group of catechol. As the DA mass fraction increases, these two peaks gradually become more obvious, as shown in the 1DA-MMT spectrum. At the same time, the peak at 3614 cm-1 corresponding to the stretching vibration of the -OH group -1 Move to higher values ​​of 3618 / 3619cm -1 , indicating that new hydrogen bonds may be formed after PDA coating on the MMT surface. In addition, for the xDA-MMT film, the H–O–H stretching and bending vibrations (3420 cm -1 and 1637cm -1 ) is weakened and lower than the intensities of N–H and C=C vibrations, which further confirms the existence of PDA between MMT layers.

[0104] Figure 13(d) The XRD spectrum shows that the interlayer spacing of the xDA-MMT film increases slightly from 1.40 nm in the 0.6DA-MMT film to 1.45 nm in the 1DA-MMT film, both of which are larger than the 1.28 nm of the intrinsic MMT film. This is consistent with the previous simulation results, that is, PDA exists between the MMT layers, and its relative content increases with the increase of the DA mass ratio. In addition, the XRD spectrum also reflects the interlayer spacing of the xDA-MMT film after heating at 200 ° C for 24 hours and hydrating in water for 24 hours. The results show that the interlayer spacing of all membranes decreases after heating and increases after hydration, which also corresponds to the loss and acquisition of free water and weakly hydrated water in the membrane, respectively. However, unlike the phenomenon that the intrinsic MMT film disintegrates in water due to excessive interlayer spacing, as the relative mass ratio of DA increases, the xDA-MMT film is less and less affected by the external environment, which is manifested in that the upper and lower fluctuation range of the membrane interlayer spacing after heating or hydration is getting smaller and smaller. In addition, as Figure 13 As shown in (e), the water contact angles of the xDA-MMT films are all less than 50°, similar to those of native MMT films, indicating the hydrophilicity of the xDA-MMT films. This stability and hydrophilicity also enable the xDA-MMT membranes to conduct protons.

[0105] Zeta potential often provides important information about the stability of colloidal systems. Figure 15 As shown in (a), during the experimental study of the present invention, the zeta potential distributions of an MMT nanosheet dispersion and an xDA-MMT nanosheet dispersion adjusted to pH 8.5 for 2 hours were measured. The zeta potential peak of the pristine MMT nanosheets is located at -52.2 mV, reflecting the inherent electronegativity of MMT. Furthermore, the absolute value of the zeta potential is greater than 30 mV, indicating that MMT can be stably present in the aqueous dispersion. For the xDA-MMT nanosheet dispersion, the zeta potential fluctuates around -41 mV, indicating that the dispersion is also stable. Furthermore, the decrease in the absolute value of the zeta potential (sliding plane potential) of the xDA-MMT nanosheet dispersion compared to the native MMT nanosheet dispersion further demonstrates that PDA can be stably coated on the surface of the MMT nanosheets. Furthermore, the negative zeta potential of the xDA-MMT nanosheet dispersion indicates that the xDA-MMT nanosheets can still attract various cations, including protons.

[0106] like Figure 14 As shown in (a), Na + / Si + The relative intensity of DA was recorded and analyzed. It was found that with the increase of the relative mass ratio of DA, the sodium ion content in the xDA-MMT film decreased. This means that when DA is added to the MMT dispersion, DA is not only absorbed as a monomer onto the MMT surface, but also Figure 15 As shown in (a), part of the sodium ions are exchanged in the form of cation exchange, and then PDA is formed on the surface. + It is bound to the original MMT area on its surface by electrostatic force, but is almost absent in the PDA-coated area. After the xDA-MMT film was proton exchanged (immersed in 1M HCl solution for several days), the Na + / Si + The relative intensity of the Na + At this time, it is effectively exchanged by protons.

[0107] Therefore, the present invention finally studies the proton conductivity of xDA-MMT film. Figure 14 (b) and Figure 15 As shown in (b) and (c), the experiment first cut rectangular film samples of xDA-MMT films of different sizes and encapsulated them into 2D nanofluidic devices using PDMS. A surface proton conductivity (σ) test platform was established, as shown in the figure. Figure 14 (c) As shown. At the beginning of each test, the study found that the xDA-MMT film sample needed to be immersed in the HCl electrolyte solution for at least 4 days to achieve sufficient proton exchange and thus obtain a stable σ value. Here, after stabilization, the surface proton conductivity of the xDA-MMT film was also tested for stability for 1 month. The final stable I–V curves of the xDA-MMT film in different concentrations of HCl electrolyte solution are shown as follows: Figure 14 (d) and Figure 15 (d), (e) The results show that the stable σ value of xDA-MMT film is positively correlated with the HCl electrolyte concentration, as shown in Figure 14 As shown in (e), this means that as long as there are enough protons, the water-stable xDA-MMT film can provide excellent proton conductivity. In other words, a "proton transport highway" is formed inside the xDA-MMT film. When 1M HCl solution is continuously used as the liquid electrolyte for 1 month, the average σ values ​​of the 0.6DA-MMT film and the 1DA-MMT film are 0.58S cm -1 and 0.45S cm -1 , and the fluctuation is very small within 1 month, such as Figure 14(f) These results indicate that the invented 0.6DA-MMT membrane can achieve a balance between high proton conductivity and aqueous phase stability. Although the surface proton conductivity of the intrinsic MMT film is about half, the average σ value of the xDA-MMT film is still higher than the maximum σ value of the NafionNR211 film tested by the same process (Nafion NR211 thickness is 25.4μm, close to that of the 0.6DA-MMT film, with a maximum σ value of 0.16Scm -1 ). In addition, if Figure 15 As shown in Figure (f), the present invention conducted drift-diffusion experiments on water-stable xDA-MMT films (injecting HCl electrolyte solutions of varying concentrations on both sides of the 2D nanofluidic device). The results show that in the presence of an HCl concentration gradient, the I–V curves remain linear, and for different xDA-MMT films, a negative zero-bias current and a positive zero-current potential of approximately 76.9 mV are observed. This value is close to the Nernst value of 59.1 mV, further confirming the cation-selective transport properties of the water-stable xDA-MMT films. In this system, proton-selective transport is also observed.

[0108] In summary, the present invention provides a high proton conductivity membrane based on partially coated montmorillonite with polydopamine and a preparation method thereof. The prepared xDA-MMT film has good hydrophilicity and is stable in water phase and has excellent surface proton conductivity, showing great potential for further forming a new generation of PEM, and also opens up new ideas for low-cost inorganic materials as new proton transport entities.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine, characterized in that: The following steps are involved: S1, taking MMT powder raw material and performing heat treatment to obtain MMT sample; S2, mixing the MMT sample after the heat treatment in step S1 with ultrapure water, stirring at high speed until the MMT sample is fully rehydrated, and then ultrasonically treating to obtain a dispersion of MMT nanosheets with uniform size; S3, adding DA powder to the MMT nanosheet dispersion obtained in step S2, and stirring thoroughly to obtain a DA and MMT dispersion system; S4, adjusting the pH value of the DA and MMT dispersion system obtained in step S3 to 8.5-9, and obtaining a dark brown PDA-MMT nanosheet dispersion after sufficient stirring; S5. The dark brown PDA-MMT nanosheet dispersion obtained in step S4 is vacuum filtered, rinsed with ultrapure water, and then naturally dried to obtain a PDA-MMT film.

2. The method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine according to claim 1, characterized in that: Step S1 is specifically as follows: The heating rate was set to 10°C / min, and the MMT powder raw material was heated at 150±5°C for 5 to 10 minutes, and then naturally cooled to perform partial dehydration of the MMT powder.

3. The method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine according to claim 1, characterized in that: In step S2, the mass volume ratio of the MMT sample to ultrapure water is (0.029-0.031) g:300 mL, the stirring time is 6-8 h, the ultrasonic treatment time is 30-35 min, and the ultrasonic power is 60-80 W.

4. The method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine according to claim 3, characterized in that: The concentration of MMT nanosheet dispersion is 0.97~1.03×10 -1 g / L.

5. The method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine according to claim 1, characterized in that: In step S3, the mass ratio of DA powder to MMT powder is (0.6-1):

1.

6. The method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine according to claim 5, characterized in that: The stirring time is 4 to 5 hours.

7. The method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine according to claim 1, characterized in that: In step S4, the stirring time is 2 to 2.5 hours to achieve the self-polymerization of DA on the surface of the MMT nanosheets, so that the PDA is partially coated on the surface of the MMT nanosheets to obtain PDA-MMT nanosheets.

8. The method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine according to claim 7, characterized in that: 20 to 25 drops of Tris-HCl buffer were added to adjust the pH value of the DA and MMT dispersion system.

9. The method for preparing a high proton conductivity membrane based on partially coated montmorillonite with polydopamine according to claim 1, characterized in that: In step S5, the vacuum filtration time is 14 to 16 hours.

10. A high proton conductivity membrane based on partially coated montmorillonite with polydopamine prepared according to the method of any one of claims 1 to 9, characterized in that: At room temperature, it has a value of 0.4~0.6S cm -1 along-surface proton conductivity.

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