zwitterionic functionalized COF and SiO 2 Sphere-modified polymer hybrid proton exchange membrane

Abstract

This invention belongs to the field of membrane technology, and specifically discloses a zwitterionic functionalized COF and SiO2. 2 The polymer hybrid proton exchange membrane with spherical co-modification includes the following steps: (1) preparing a covalent organic framework SNW-1; (2) reacting SNW-1 with 1,3-propanesulfonic acid lactone to obtain zwitterionic functionalized covalent organic framework ZSNW-1; (3) preparing SiO2. 2 Nanospheres; (4) ZSNW-1 and SiO 2 Nanospheres were added to a sulfonated polymer solution at a mass ratio of 2:1 to ultimately prepare zwitterionic functionalized covalent organic frameworks COF and SiO2. 2 A polymer hybrid proton exchange membrane with spherical synergistic modification. This invention improves the structure and composition of key functional components in the proton exchange membrane by introducing zwitterionic-functionalized covalent organic frameworks ZSNW-1 and SiO2 into the proton exchange membrane. 2 Nanospheres, with their mass ratio controlled at 2:1, can effectively improve proton conductivity by utilizing their synergistic modification effect.

Description

zwitterionic functionalized COF and SiO2 sphere synergistic modification of polymer hybrid proton exchange membranes Technical Field

[0001] This invention belongs to the field of membrane technology, and more specifically, relates to a polymer hybrid proton exchange membrane synergistically modified with zwitterionic functionalized COF and SiO2 nanospheres. By introducing zwitterionic functionalized covalent organic framework (ZSNW-1) and SiO2 nanospheres to synergistically modify the polymer hybrid proton exchange membrane, the proton conductivity of the prepared proton exchange membrane can be effectively improved. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are among the most promising energy conversion devices currently available, attracting widespread attention from industry and academia due to their high energy conversion efficiency (directly converting chemical energy into electrical energy), fast start-up speed, and environmental friendliness. The proton exchange membrane (PEM), as a crucial component of the PEMFC, plays a vital role in its performance. It not only provides a pathway for proton transport but also prevents electron leakage and fuel leakage between the anode and cathode. Proton conductivity is one of the most important parameters for evaluating PEMFC performance, and improving proton conductivity is an effective way to improve PEMFC performance.

[0003] Covalent organic frameworks (COFs) possess characteristics such as large specific surface area, tunable structure, high porosity, and excellent thermal and chemical stability. In recent years, COFs have shown great potential in proton conduction. Studies have found that their highly ordered pore structure not only provides a fast channel for proton migration, but also allows for the accommodation of more guest molecules within the pores to further enhance their proton transport capacity. Therefore, more and more COF materials are being introduced into polymer hybrid proton exchange membranes to improve the proton conduction performance of proton exchange membranes. For example, the Journal of Membrane Science (655(2022)120603) reported the in-situ synthesis of COF-316 in poly[2,2'-(p-oxydiphenyl)-5,5'-bisbenzimidazole] (OPBI) to prepare a COF-316 / OPBI hybrid proton exchange membrane, which achieved a proton conductivity of 0.178 S / cm at 160 °C, a significant improvement over the unmodified PBI membrane. The *Journal of Power Sources* (554(2023)232332) reported the preparation of a P-COF / Nafion hybrid membrane by adding phosphotungstic acid (HPW)-functionalized COF (P-COF) to the perfluorosulfonic acid resin Nafion. This membrane achieved a proton conductivity of 0.130 S / cm at 80 °C and 55% RH, a significant improvement over the unmodified Nafion membrane. The *Chinese Journal of Electrochemistry* (331(2020)135235) reported the preparation of an H3PO4@CTFp / SPEEK hybrid proton exchange membrane by adding a phosphoric acid-supported covalent triazine framework (H3PO4@CTFp) to a sulfonated polyether ether ketone (SPEEK) matrix. This membrane achieved a proton conductivity of 0.313 S / cm at 80 °C and 100% RH, a significant improvement over the unmodified SPEEK membrane. The journal *Chemical Materials A* (2023, 11, 3446) reported the preparation of a ZUT-COT-SO3H@Nafion hybrid proton exchange membrane by incorporating a sulfonate-functionalized hydrophilic two-dimensional COF (ZUT-COT-SO3H) into the perfluorosulfonic acid resin Nafion. This membrane achieved a proton conductivity of 0.134 S / cm at 80°C and 80% RH, a significant improvement compared to the pure Nafion membrane. However, these methods directly functionalize the COF to enhance the proton conductivity of the polymer hybrid proton exchange membrane, resulting in limited improvement in proton conductivity.

[0004] As is well known, the hygroscopicity of proton exchange membranes is one of the important factors affecting their proton transport performance. Studies have found that the inorganic filler SiO2 exhibits strong hydrophilicity due to the presence of many hydroxyl functional groups on its surface. Using it as a filler to modify polymer hybrid proton exchange membranes can not only greatly improve the membrane's water retention capacity but also facilitate the construction of a dynamic hydrogen bond network to promote proton conduction. Therefore, more and more researchers are introducing this hygroscopic particle into polymer hybrid proton exchange membranes to modify the hybrid membranes. For example, the journal *Chemical Materials A* (2015, 3, 18546-18556) reported the preparation of a SiO2@sPS / Nafion hybrid membrane by adding sulfonated SiO2@PS core-shell nanoparticles (SiO2@sPS) to a Nafion matrix. This membrane exhibited a proton conductivity of approximately 0.260 S / cm at 90℃ and 100% RH, which is a significant improvement over the original Nafion membrane. The International Journal of Energy Research (2019, 43, 5333-5345) reported an f-SiO2 / SPAEK hybrid proton exchange membrane obtained by adding sulfonic acid-functionalized SiO2 (f-SiO2) to a SPAEK matrix. The membrane exhibited a proton conductivity of approximately 0.200 S / cm at 90 °C and 100% RH, which was significantly higher than that of the unmodified SPAEK membrane. The *International Journal of Hydrogen Energy* (43(2018) 21940-21948) reported on the modification of SPEEK membranes by doping HPW-loaded mesoporous SiO2 (HPW@MSNs) into the SPEEK matrix. The resulting HPW@MSNs / SPEEK hybrid proton exchange membrane exhibited a proton conductivity of 0.180 S / cm at 60 °C and 100% RH, significantly improving the proton conductivity compared to the unmodified SPEEK membrane. *Polymer Testing* (59(2017) 423-429) reported on the MHSi / Nafion hybrid membrane prepared by incorporating mesoporous hollow silicon spheres (MHSi) into Nafion, which effectively enhanced the proton conductivity compared to the unmodified Nafion membrane.

[0005] Although the proton conductivity of these COFs and SiO2 modified films has been improved, the improved proton conductivity is not high enough and there is still considerable room for improvement. Summary of the Invention

[0006] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a polymer hybrid proton exchange membrane synergistically modified with zwitterionic-functionalized COF and SiO2 nanospheres. This is achieved by improving the structure and composition of key functional components in the proton exchange membrane, introducing zwitterionic-functionalized covalent organic framework (ZSNW-1) and SiO2 nanospheres into the membrane, and controlling their mass ratio at 2:1 to synergistically modify the polymer hybrid proton exchange membrane. Furthermore, the overall process design of the preparation method is controlled. The resulting zwitterionic-functionalized COF and SiO2 nanosphere-synergistically modified polymer hybrid proton exchange membrane effectively improves proton conductivity compared to existing technologies. This invention, by introducing zwitterionic-functionalized covalent organic framework (ZSNW-1) and SiO2 nanospheres to synergistically modify the polymer hybrid proton exchange membrane, effectively improves the proton conductivity of the prepared proton exchange membrane. A proton exchange membrane with significantly improved proton conductivity and excellent stability can be obtained through a simple process.

[0007] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a zwitterionic functionalized COF and SiO2 nanosphere synergistically modified polymer hybrid proton exchange membrane is provided, characterized by comprising the following steps:

[0008] (1) Melamine and terephthalaldehyde were added to dimethyl sulfoxide (DMSO) and sonicated to fully dissolve and disperse them to form a precursor solution. Then, the precursor solution was stirred and reacted at 100-210°C under a protective gas atmosphere for 6-45 hours. The product was then separated and washed to obtain a covalent organic framework (COF), denoted as SNW-1.

[0009] (2) Add the SNW-1 obtained in step (1) to acetonitrile, sonicate it to disperse it fully, then add 1,3-propanesulfonic acid lactone, and stir the reaction for 10-30 h at 30-100 °C under a protective gas atmosphere; then separate and wash the product to obtain zwitterionic functionalized covalent organic framework, denoted as ZSNW-1.

[0010] (3) Dissolve the surfactant and catalyst in deionized water and stir thoroughly to form solution A; dissolve the silicon precursor in a mixture of co-surfactant and organic solvent and stir thoroughly to form solution B; then add solution A to solution B and stir thoroughly to form reaction stock solution, and transfer the reaction solution to a flask and reflux at 30-100℃ for 10-30h; then separate and wash the product to obtain SiO2 nanospheres;

[0011] (4) The ZSNW-1 obtained in step (2) and the SiO2 nanospheres obtained in step (3) are added to the sulfonated polymer solution at a mass ratio of 2:1 and ultrasonically treated to obtain a uniformly dispersed casting solution. Then, the casting solution is used to form a membrane material. After drying, the membrane is then subjected to hydrogen peroxide solution, acid and deionized water immersion treatment in sequence to obtain a polymer hybrid proton exchange membrane with zwitterionic functionalized covalent organic framework COF and SiO2 nanospheres synergistic modification.

[0012] As a further preferred embodiment of the present invention, in step (1), the molar ratio of melamine to terephthalaldehyde is 1:0.5 to 1:6; and the protective gas is either nitrogen or argon.

[0013] As a further preferred embodiment of the present invention, in step (2), the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:3 to 1:7; the protective gas is either nitrogen or argon.

[0014] As a further preferred embodiment of the present invention, in step (3), the catalyst is one or a mixture of several of urea, ammonia, NaOH solution, and triethanolamine (TEA);

[0015] The surfactant is one or a mixture of several of the following: hexadecyltrimethylammonium bromide (CTAB), octadecyltrimethylammonium bromide (OTAB), sodium dodecylbenzenesulfonate (SDBS), and hexadecyltrimethylammonium chloride (CTAC).

[0016] The co-surfactant is one or a mixture of several of isopropanol, butanol, and n-pentanol;

[0017] The silicon precursor is one or a mixture of several of tetraethyl orthosilicate (TEOS) and 1,2-bis(triethoxysilyl)ethane (BTSE);

[0018] The organic solvent is one or a mixture of cyclohexane and toluene.

[0019] As a further preferred embodiment of the present invention, in step (4), the sum of the amounts of ZSNW-1 and SiO2 nanospheres added accounts for 0.4 to 2.2 wt% of the mass of the sulfonated polymer matrix; preferably, the sum of the amounts of ZSNW-1 and SiO2 nanospheres added accounts for 1.0 to 1.4 wt% of the mass of the sulfonated polymer matrix.

[0020] As a further preferred embodiment of the present invention, in steps (1), (2), and (3), the solvent used for cleaning is independently selected from one or a mixture of several of CH3OH, C2H5OH, CHCl3, CH2Cl2, CH3Cl, acetone, butanone, and tetrahydrofuran.

[0021] As a further preferred embodiment of the present invention, in step (4), the sulfonated polymer solution is one of a homogeneous solution of perfluorosulfonic acid resin, sulfonated polyether ether ketone, sulfonated polybenzimidazole, sulfonated polyether sulfone, or sulfonated polyimide; the concentration of the sulfonated polymer solution is 1 to 40 wt%.

[0022] The casting solution is used to form a film material, specifically by coating the casting solution into a film;

[0023] The drying process involves placing the membrane material in an oven at 50–80°C, raising the temperature to 110–150°C, and then maintaining the temperature for 12–36 hours. Preferably, the heating rate is less than 0.5°C / min, and more preferably 0.1–0.5°C / min.

[0024] As a further preferred embodiment of the present invention, in step (4), the concentration of the hydrogen peroxide solution is 1 to 10 wt%; the acid solution is specifically a mixture of one or more of hydrochloric acid, sulfuric acid, and phosphoric acid, and the concentration of the acid solution is 0.1 to 4 mol / L.

[0025] According to another aspect of the present invention, the present invention provides a polymer hybrid proton exchange membrane prepared by the above preparation method, which is functionalized by zwitterion-induced COF and SiO2 nanospheres and synergistically modified.

[0026] According to another aspect of the present invention, the present invention provides the application of the above-mentioned zwitterionic functionalized COF and SiO2 nanosphere synergistically modified polymer hybrid proton exchange membrane in proton exchange membrane fuel cells.

[0027] Compared with the traditional COF-modified polymer hybrid proton exchange membrane process, the above-described technical solution of this invention introduces zwitterionic-functionalized COF (ZSNW-1) and hygroscopic particles SiO2 into the proton exchange membrane. After zwitterionic functionalization, ZSNW-1 becomes a porous nanoparticle with a certain degree of hydrophilicity, which can enhance the water retention capacity of the hybrid proton exchange membrane. However, the chemical composition of ZSNW-1 itself is mostly hydrophobic aromatic rings, and the surface hydroxyl groups of the hygroscopic nanoparticles SiO2 can interact with the zwitterionic ions of ZSNW-1 through hydrogen bonds and electrostatic interactions. The interaction is distributed around ZSNW-1 to further optimize its hydrophilic environment, enabling a more effective proton-transferring hydrogen bond network to form between ZSNW-1, SiO2, and bound water. On the other hand, the surface hydroxyl groups of SiO2 nanoparticles are relatively weak in proton transfer compared to common groups such as -SO3H and -PO3H2. After co-doping, the hydrogen bonding and electrostatic interaction between the zwitterions of ZSNW-1 and SiO2 makes the surface hydroxyl groups more orderly distributed. They can synergistically transfer protons with the zwitterions of ZSNW-1, thereby better leveraging the proton transfer function of hydroxyl groups. This synergistic effect greatly improves the proton conductivity of the hybrid proton exchange membrane prepared in this invention. As shown in Figure 2 below, the proton conductivity of the hybrid membrane (ZSNW-1+SiO2(2:1) / RN) obtained when the mass ratio of ZSNW-1 to SiO2 co-doping is 2:1 is significantly better than that of the unhybridized membrane (RN), the hybrid membrane (ZSNW-1 / RN and SiO2 / RN) obtained by single doping of ZSNW-1 and single doping of SiO2.

[0028] Furthermore, the co-doping mass ratio of ZSNW-1 to SiO2 in this invention has a significant impact on the proton conductivity of the resulting hybrid proton exchange membrane, requiring strict control of the ZSNW-1 to SiO2 co-doping mass ratio at 2:1. As shown in Figure 1 below, when the ZSNW-1 to SiO2 co-doping mass ratio is 2:1, the proton conductivity of the resulting hybrid membrane is significantly improved. This is mainly because, at this suitable ratio, SiO2 can be more uniformly distributed around ZSNW-1 (the hydroxyl groups on the SiO2 surface and the zwitterions of ZSNW-1 have hydrogen bonds and electrostatic interactions), thus optimizing the hydrophilic environment of ZSNW-1 to a greater extent. This allows for the formation of a hydrogen bond network among ZSNW-1, SiO2, and bound water that is more conducive to proton transport. Simultaneously, the hydrogen bonds and electrostatic interactions between the zwitterions of ZSNW-1 and SiO2 result in a higher degree of order in the distribution of its surface hydroxyl groups. This, in turn, allows SiO2 and ZSNW-1 to form an effective synergistic effect, greatly promoting proton transport. When the mass ratio of ZSNW-1 to SiO2 co-doping is less than 2:1, the amount of SiO2 is relatively large, resulting in a relatively low uniformity of its distribution around ZSNW-1, and it may even agglomerate. Consequently, the water affinity environment around ZSNW-1 is not optimized enough, leading to a greater resistance to proton transfer in the hydrogen bond network formed between ZSNW-1, SiO2, and bound water compared to the 2:1 ratio. Taking Example 1 below as an example, the proton conductivity of the hybrid film (ZSNW-1+SiO2(1:1) / RN) obtained when the mass ratio of ZSNW-1 to SiO2 co-doping is 1:1 is significantly lower than that of the hybrid film (ZSNW-1+SiO2(2:1) / RN) obtained when the mass ratio of ZSNW-1 to SiO2 co-doping is 2:1 (as shown in Figure 1 below), and is on par with the proton conductivity of the ZSNW-1 hybrid proton exchange membrane obtained by using only ZSNW-1 and with the same amount of addition (as described in Comparative Example 1 below). When the co-doping mass ratio of ZSNW-1 to SiO2 is greater than 2:1, the amount of SiO2 is relatively small. This results in insufficient water supply from the hygroscopic particles SiO2 to the environment surrounding ZSNW-1, thus worsening the hydrophilic environment around ZSNW-1. Consequently, the resistance to proton transfer in the hydrogen bond network formed between ZSNW-1, SiO2, and bound water is greater than that at a 2:1 ratio. Therefore, the proton conductivity of the hybrid film (ZSNW-1+SiO2(3:1) / RN) obtained when the co-doping mass ratio of ZSNW-1 to SiO2 is 3:1 is lower than that of the hybrid film (ZSNW-1+SiO2(2:1) / RN) obtained when the co-doping mass ratio of ZSNW-1 to SiO2 is 2:1, as shown in Figure 1 below.Therefore, the appropriate doping ratio of ZSNW-1 to SiO2 is crucial for ZSNW-1 and SiO2 to effectively exert their synergistic effect and greatly promote the proton conduction of the hybrid film. This invention strictly controls the mass ratio of ZSNW-1 and SiO2 co-doping to 2:1, which effectively ensures the synergistic effect.

[0029] The preparation method of this invention is as follows: First, zwitterionic functionalized covalent organic framework ZSNW-1 and SiO2 nanospheres are prepared. Then, the two are doped into a polymer in a certain ratio to obtain a polymer hybrid proton exchange membrane synergistically modified by zwitterionic functionalized COF and SiO2 nanospheres. For ZSNW-1, the covalent organic framework (SNW-1) is first synthesized, and then SNW-1 undergoes a ring-opening reaction with 1,3-propanesulfonic acid lactone to obtain zwitterionic functionalized covalent organic framework ZSNW-1.

[0030] The operation process of this invention is extremely simple, the production cost is low, the preparation conditions are mild, it is easy to mass-produce and scale up, and it has a good industrial production foundation and broad application prospects.

[0031] Compared to some existing technologies, such as the proton exchange membrane obtained by the inventors of this invention in their previous research on "Polymer Hybrid Proton Exchange Membranes Modified by Covalent Organic Framework Structures and Their Preparation" (see Chinese patent document with application number 2022112947562), although it also involves polymer proton exchange membranes modified by covalent organic framework materials (ZSNW-1) and their preparation, the material used in that previous research was a composite nanomaterial CNT@ZSNW-1 of carbon nanotubes (CNT) and covalent organic framework materials (ZSNW-1). CNT@ZSNW-1 is a single-form composite particle, which is prepared by in-situ growth of SNW-1 on the surface of CNT and then functionalization with zwitterions. During the preparation process, it is necessary to effectively control the morphology so that the ZSNW-1 structure is interconnected and uniformly distributed on the surface of CNT. The particles used in this invention are two types of nanoparticles: modified COF particles (ZSNW-1) and SiO2 nanospheres. These two types of nanoparticles can be directly doped into a polymer matrix through simple physical blending, without the need for precise control of the morphology of the modified COF particles (ZSNW-1) during the preparation process. It is evident that not only are the interaction mechanisms between the doped particles different, but the preparation processes are also significantly different. Furthermore, the morphology of the SiO2 nanospheres used in this invention differs from that of common SiO2 nanospheres. In this invention, the surfactant and catalyst are first dissolved in deionized water and stirred thoroughly to form solution A. Simultaneously, the silicon precursor is dissolved in a mixture of co-surfactant and organic solvent and stirred thoroughly to form solution B. Next, solution A is added to solution B and stirred thoroughly to form the reaction stock solution. The reaction solution is then transferred to a flask and refluxed at 30–100°C for 10–30 hours to obtain SiO2 nanospheres, which are three-dimensional dendritic SiO2 nanospheres (as shown in Figure 3). Compared to common SiO2 nanospheres, the unique three-dimensional radial channels of the three-dimensional dendritic SiO2 nanospheres result in a larger pore volume, higher specific surface area, and more proton transport functional sites. More importantly, the mechanisms by which the two improve the proton conductivity of polymer hybrid proton exchange membranes also differ. Previous research primarily focused on how the superior coherent structure of CNT@ZSNW-1 enhances the continuity of proton transport channels between COF particles and between COF particles and the membrane matrix, thereby reducing proton transport resistance in hybrid proton exchange membranes and ultimately improving their proton conductivity. This invention, however, primarily enhances the proton conductivity of hybrid proton exchange membranes by co-doping ZSNW-1 and SiO2 nanoparticles into a polymer matrix, achieving a synergistic effect.After zwitterionic functionalization, ZSNW-1 becomes a porous nanoparticle with certain hydrophilicity, which can enhance the water retention capacity of the hybrid proton exchange membrane. However, the chemical composition of ZSNW-1 itself is mostly hydrophobic aromatic rings. The surface hydroxyl groups of the hygroscopic nanoparticle SiO2 can interact with the zwitterionic groups of ZSNW-1 through hydrogen bonds and electrostatic interactions to distribute around ZSNW-1, further optimizing its hydrophilic environment. This allows for the formation of a more effective proton-transferring hydrogen bond network among ZSNW-1, SiO2, and bound water. On the other hand, the surface hydroxyl groups of SiO2 nanoparticles themselves are relatively weak in proton transfer compared to common groups such as -SO3H and -PO3H2. After co-doping, the hydrogen bonds and electrostatic interactions between the zwitterionic groups of ZSNW-1 and SiO2 make the surface hydroxyl groups more orderly distributed, and they can synergistically transfer protons with the zwitterionic groups of ZSNW-1, thereby better utilizing the proton transfer function of hydroxyl groups. This synergistic effect greatly improves the proton conductivity of the hybrid proton exchange membrane prepared in this invention.

[0032] For example, compared to the previous study in *Journal of Membrane Science* (568(2018)1-9), which also involved zwitterionic functionalized COF (ZSNW-1) modified polymer hybrid proton exchange membranes and their preparation, that previous study only used a single ZSNW-1 particle, while this invention uses both ZSNW-1 and SiO2 particles. Furthermore, that previous study mainly improved the proton conduction rate by increasing the water retention capacity of the hybrid membrane through ZSNW-1, accelerating the transfer of protons through the water network and the dissociation of the proton donor (-SO3H). This invention, however, primarily improves the proton conductivity of the hybrid proton exchange membrane by co-doping both ZSNW-1 and SiO2 nanoparticles into the polymer matrix, achieving a synergistic effect. After zwitterionic functionalization, ZSNW-1 becomes a porous nanoparticle with certain hydrophilicity, which can enhance the water retention capacity of the hybrid proton exchange membrane. However, the chemical composition of ZSNW-1 itself is mostly hydrophobic aromatic rings. The surface hydroxyl groups of the hygroscopic nanoparticle SiO2 can interact with the zwitterionic groups of ZSNW-1 through hydrogen bonds and electrostatic interactions to distribute around ZSNW-1, further optimizing its hydrophilic environment. This allows for the formation of a more effective proton-transferring hydrogen bond network among ZSNW-1, SiO2, and bound water. On the other hand, the surface hydroxyl groups of SiO2 nanoparticles themselves are relatively weak in proton transfer compared to common groups such as -SO3H and -PO3H2. After co-doping, the hydrogen bonds and electrostatic interactions between the zwitterionic groups of ZSNW-1 and SiO2 make the surface hydroxyl groups more orderly distributed, and they can synergistically transfer protons with the zwitterionic groups of ZSNW-1, thereby better utilizing the proton transfer function of hydroxyl groups. This synergistic effect greatly improves the proton conductivity of the hybrid proton exchange membrane prepared in this invention. In another aspect, the proton exchange membrane prepared in the previous research embodiment has a maximum proton conductivity of 0.220 S / cm at 80°C and 100% RH, which is lower than the maximum proton conductivity of 0.272 S / cm of the proton exchange membrane prepared in the embodiment of the present invention at 90°C and 95% RH.

[0033] Furthermore, compared to the previous study in the *Journal of the Electrochemical Society* (159(11)F702-F710(2012)), although it also involved the preparation of polymer hybrid proton exchange membranes modified with hygroscopic SiO2 nanospheres, the SiO2 nanospheres added were common ordinary SiO2 nanospheres. The Nafion / silica hybrid membrane prepared by doping Nafion matrix with SiO2 nanospheres had a maximum proton conductivity of only 0.103 S / cm at 80°C and 100% RH, which is far lower than the proton conductivity of the hybrid membrane prepared by doping three-dimensional dendritic SiO2 nanoparticles in Nafion matrix in this invention (as shown in Comparative Example 2 below). The previous study in *Soft Matter*... Matter (2022, 18, 3342) also reported the fabrication of a Nafion / UF-silica hybrid proton exchange membrane by incorporating unmodified ordinary SiO2 nanoparticles into a Nafion matrix. This membrane exhibited a maximum proton conductivity of approximately 0.095 S / cm at room temperature and 100% RH, which is also lower than the proton conductivity of the hybrid membrane fabricated by doping the present invention with three-dimensional dendritic SiO2 nanoparticles in a Nafion matrix (as shown in Comparative Example 2 below). Therefore, the three-dimensional dendritic SiO2 nanoparticles used in this invention are also crucial for improving the proton conductivity of the hybrid membrane.

[0034] In summary, this invention utilizes zwitterionic-functionalized COF (ZSNW-1) and three-dimensional dendritic SiO2 nanoparticles to construct a more efficient proton-transfer hydrogen bond network within a polymer matrix. Specifically, the hygroscopic SiO2 nanoparticles optimize the hydrophilic environment surrounding ZSNW-1, significantly enhancing the membrane's water retention capacity and thus greatly promoting proton conduction. ZSNW-1 also contributes to a more ordered distribution of hydroxyl groups on the SiO2 surface, allowing for better proton transfer. This invention, through the co-doping and synergistic modification of polymer hybrid proton exchange membranes using zwitterionic-functionalized covalent organic framework ZSNW-1 and SiO2 nanospheres, yields modified proton exchange membranes exhibiting excellent performance in both proton transfer and operational stability. Attached Figure Description

[0035] Figure 1 is a comparison of the temperature-dependent proton conductivity of zwitterionic functionalized COF (ZSNW-1) and SiO2 nanosphere-modified polymer hybrid proton exchange membranes (ZSNW-1 to SiO2 doping mass ratios of 1:1, 2:1, and 3:1, respectively) and unhybridized proton exchange membranes obtained in Examples 1, 2, and 3 of this invention (95% RH, RH: relative humidity). In the figures, “RN” represents an unhybridized proton exchange membrane; “ZSNW-1+SiO2(1:1) / RN” represents a ZSNW-1+SiO2 hybridized proton exchange membrane with a ZSNW-1 to SiO2 doping ratio of 1:1 (i.e., the sample obtained in Example 1); “ZSNW-1+SiO2(2:1) / RN” represents a ZSNW-1+SiO2 hybridized proton exchange membrane with a ZSNW-1 to SiO2 doping ratio of 2:1 (i.e., the sample obtained in Example 2); and “ZSNW-1+SiO2(3:1) / RN” represents a ZSNW-1+SiO2 hybridized proton exchange membrane with a ZSNW-1 to SiO2 doping ratio of 3:1 (i.e., the sample obtained in Example 3).

[0036] Figure 2 shows a comparison of the temperature-dependent proton conductivity (95% RH) of proton exchange membranes hybridized with ZSNW-1 and SiO2, respectively, and those without hybridization. In the figure, “RN” represents the unhybridized proton exchange membrane; “ZSNW-1 / RN” represents the ZSNW-1 hybridized proton exchange membrane (i.e., the sample obtained in Comparative Example 1); “SiO2 / RN” represents the SiO2 hybridized proton exchange membrane (i.e., the sample obtained in Comparative Example 2); and “ZSNW-1+SiO2(2:1) / RN” represents the ZSNW-1+SiO2 hybridized proton exchange membrane with a ZSNW-1 to SiO2 doping ratio of 2:1 (i.e., the sample obtained in Example 2).

[0037] Figure 3 is a TEM image of the SiO2 spheres obtained in step (3) of Example 1. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0039] The polymer hybrid proton exchange membrane synergistically modified with zwitterionic-functionalized COF and SiO2 nanospheres in this invention is prepared by first separately preparing zwitterionic-functionalized covalent organic framework (ZSNW-1) and SiO2 nanospheres, and then doping them into a polymer in a certain ratio to obtain the polymer hybrid proton exchange membrane synergistically modified with zwitterionic-functionalized COF and SiO2 nanospheres. Specific embodiments are as follows:

[0040] Example 1

[0041] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0042] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0043] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres (i.e., SiO2 nanospheres; the same below).

[0044] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 1:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly. Carefully pour the dispersion into a mold and quickly place it in an 80℃ oven. Start at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, and then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0045] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.237 S / cm at 90°C and 95% RH, which is approximately 0.62 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane, as shown in Figure 1. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0046] In addition, the SiO2 spheres obtained in step (3) were characterized by TEM, and the results are shown in Figure 3, which show a three-dimensional dendritic structure.

[0047] Example 2

[0048] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0049] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0050] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0051] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0052] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.272 S / cm at 90°C and 95% RH, which is approximately 0.86 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane, as shown in Figure 1. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0053] Example 3

[0054] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0055] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0056] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0057] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 3:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0058] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.243 S / cm at 90°C and 95% RH, which is approximately 0.66 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane, as shown in Figure 1. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0059] Example 4

[0060] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0061] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0062] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0063] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, accounting for 0.4 wt% of the Nafion solution solute, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0064] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.190 S / cm at 90°C and 95% RH, which is approximately 0.30 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0065] Example 5

[0066] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0067] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0068] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0069] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly. Carefully pour the dispersion into a mold and quickly place it in an 80℃ oven. Start at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, and then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0070] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.260 S / cm at 90°C and 95% RH, which is approximately 0.78 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0071] Example 6

[0072] 1. Weigh 0.47 g of melamine and 0.25 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:0.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0073] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0074] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0075] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0076] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity of up to 0.239 S / cm at 90°C and 95% RH, which is approximately 0.64 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0077] Example 7

[0078] 1. Weigh 0.47 g of melamine and 3.00 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:6) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0079] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0080] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0081] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0082] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity of up to 0.247 S / cm at 90°C and 95% RH, which is approximately 0.69 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0083] Example 8

[0084] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0085] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.3 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:3) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone solvent, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0086] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0087] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0088] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity of up to 0.235 S / cm at 90°C and 95% RH, which is approximately 0.61 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0089] Example 9

[0090] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0091] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.7 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:7) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone solvent, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0092] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0093] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0094] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.260 S / cm at 90°C and 95% RH, which is approximately 0.78 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0095] Example 10

[0096] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 100 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0097] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0098] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0099] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0100] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.240 S / cm at 90°C and 95% RH, which is approximately 0.64 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0101] Example 11

[0102] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 210 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0103] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0104] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0105] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0106] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.259 S / cm at 90°C and 95% RH, which is approximately 0.77 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0107] Example 12

[0108] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 6 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0109] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0110] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0111] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0112] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.230 S / cm at 90°C and 95% RH, which is approximately 0.58 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0113] Example 13

[0114] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 45 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0115] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0116] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0117] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0118] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.270 S / cm at 90°C and 95% RH, which is approximately 0.85 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0119] Example 14

[0120] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0121] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 30 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone solvent, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0122] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0123] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0124] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.230 S / cm at 90°C and 95% RH, which is approximately 0.58 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0125] Example 15

[0126] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0127] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 100 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone solvent, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0128] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0129] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0130] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity of up to 0.256 S / cm at 90°C and 95% RH, which is approximately 0.75 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0131] Example 16

[0132] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0133] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 10 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0134] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0135] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0136] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.240 S / cm at 90°C and 95% RH, which is approximately 0.64 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0137] Example 17

[0138] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0139] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 30 h. Centrifuge to separate the product, wash it with fresh acetone solvent, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0140] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0141] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0142] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.263 S / cm at 90°C and 95% RH, which is approximately 0.80 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0143] Example 18

[0144] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0145] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0146] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 30 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0147] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0148] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.238 S / cm at 90°C and 95% RH, which is approximately 0.63 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0149] Example 19

[0150] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0151] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0152] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 100 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0153] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0154] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity of up to 0.254 S / cm at 90°C and 95% RH, which is approximately 0.74 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0155] Example 20

[0156] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0157] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0158] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 10 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0159] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0160] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity of up to 0.243 S / cm at 90°C and 95% RH, which is approximately 0.66 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0161] Example 21

[0162] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0163] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0164] 3. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 30 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0165] 4. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 and SiO2 (doping mass ratio ZSNW-1:SiO2 = 2:1) to the above Nafion solution, and sonicate for 1 h to disperse them evenly; carefully pour the dispersion into a mold and quickly place it in an 80℃ oven, starting at 80℃ for 2 h, then slowly increase the temperature to 120℃ and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80℃ for 2 h, then acidify it with 1 M H2SO4 at 80℃ for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1+SiO2 hybrid proton exchange membrane.

[0166] The proton exchange membrane prepared in this embodiment exhibits a proton conductivity as high as 0.270 S / cm at 90°C and 95% RH, which is approximately 0.85 times higher (0.146 S / cm) than the unmodified Nafion proton exchange membrane. After being kept constant at 90°C and 95% RH for approximately 1570 min, the proton conductivity showed almost no decrease.

[0167] Comparative Example 1

[0168] 1. Weigh 0.47 g of melamine and 0.75 g of terephthalaldehyde (the molar ratio of melamine to terephthalaldehyde is ~1:1.5) and add them to 25 mL of dimethyl sulfoxide (DMSO). Sonicate the mixture to dissolve and disperse it into a uniform SNW-1 precursor solution. Transfer the solution to a flask and stir continuously at 180 °C under an argon atmosphere for 28 h. Separate the reaction product by centrifugation, wash it sequentially with fresh tetrahydrofuran (THF) and methanol solvent, and then vacuum dry it to obtain the covalent organic framework (SNW-1).

[0169] 2. Weigh 100 mg of SNW-1 and place it in 15 mL of acetonitrile. Sonicate the mixture to disperse it evenly. Transfer the mixture to a flask and heat it to 70 °C under a nitrogen atmosphere. Then, add a mixture of 0.5 g of 1,3-propanesulfonic acid lactone and 5 mL of acetonitrile (the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:5) dropwise over half an hour. Keep stirring and react for 24 h. Centrifuge to separate the product, wash it with fresh acetone, and then vacuum dry it to obtain zwitterionic functionalized covalent organic framework (ZSNW-1).

[0170] 3. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add ZSNW-1 (1.2 wt% of the Nafion solution solute) to the above Nafion solution and sonicate for 1 h to disperse it evenly. Carefully pour the dispersion into a mold and quickly place it in an 80°C oven. Start at 80°C for 2 h, then slowly increase the temperature to 120°C and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80°C for 2 h, then acidify it with 1 M H2SO4 at 80°C for 1 h to convert the membrane to H2O. + The membrane is then soaked in deionized water to obtain the ZSNW-1 hybrid proton exchange membrane.

[0171] The proton exchange membrane prepared in this comparative example has a proton conductivity of up to 0.238 S / cm at 90 °C and 95% RH, which is about 0.63 times higher than that of the unmodified Nafion proton exchange membrane (0.146 S / cm).

[0172] The proton conductivity of the proton exchange membrane prepared in Comparative Example 1 at 90°C and 95% RH was lower than that of the proton exchange membrane prepared in Example 2 at 90°C and 95% RH, indicating the significant advantage of ZSNW-1 and SiO2 co-doping in improving the proton conductivity of the proton exchange membrane.

[0173] Comparative Example 2

[0174] 1. Dissolve hexadecyltrimethylammonium bromide (CTAB) (1.0 g) and urea (0.6 g) in 30 mL of deionized water and stir thoroughly to form solution A; dissolve tetraethyl orthosilicate (TEOS) (2.5 g) in a mixture of isopropanol (0.92 mL) and cyclohexane (30 mL) and stir thoroughly to form solution B; then, add solution A to solution B and stir thoroughly to form the reaction stock solution, and transfer the reaction solution to a flask and reflux at 70 °C for 16 h; then separate the product, wash it with deionized water and ethanol in sequence, and dry it to obtain SiO2 spheres.

[0175] 2. Take 4 mL of commercially available Nafion solution (5 wt%), remove about half of the solvent by rotary evaporation, add 4 mL of DMF, and continue rotary evaporation for 10 min. Add 1.2 wt% SiO2 to the above Nafion solution and sonicate for 1 h to disperse it evenly. Carefully pour the dispersion into a mold and quickly place it in an 80°C oven. Start at 80°C for 2 h, then slowly increase the temperature to 120°C and maintain it for 24 h. Finally, soak the membrane in 3 wt% H2O2 solution at 80°C for 2 h, then acidify it with 1 M H2SO4 at 80°C for 1 h to convert the membrane to H2O. +The membrane is then soaked in deionized water to obtain a SiO2 hybrid proton exchange membrane.

[0176] The proton exchange membrane prepared in this embodiment has a proton conductivity of up to 0.225 S / cm at 90°C and 95% RH, which is about 0.54 times higher than that of the unmodified Nafion proton exchange membrane (0.146 S / cm).

[0177] The proton conductivity of the proton exchange membrane prepared in this comparative example at 90°C and 95% RH is lower than that of the proton exchange membrane prepared in Example 2 at 90°C and 95% RH, indicating the significant advantage of ZSNW-1 and SiO2 co-doping in improving the proton conductivity of the proton exchange membrane.

[0178] In addition to the above embodiments, the sulfonated polymer solution (the sulfonated polymer is the matrix material constituting the proton exchange membrane) can be any of the following besides the commercially available Nafion solution: other perfluorosulfonic acid resins, sulfonated polyether ether ketones, sulfonated polybenzimidazoles, sulfonated polyether sulfones, or sulfonated polyimides. The solvent in the sulfonated polymer solution is a solvent that can enable the sulfonated polymer to form a homogeneous solution.

[0179] Furthermore, all raw materials used in the above embodiments, unless otherwise specified, were commercially available. Additionally, the proton conductivity testing conditions (temperature and humidity) in the above embodiments are merely examples; testing can be performed under other temperature and / or humidity conditions depending on the actual situation. Generally, at higher humidity (greater than or equal to 90% RH), proton conductivity increases with increasing temperature.

[0180] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a zwitterionic functionalized COF and SiO2 nanosphere synergistically modified polymer hybrid proton exchange membrane, characterized in that, Includes the following steps: (1) Melamine and terephthalaldehyde were added to dimethyl sulfoxide (DMSO) and sonicated to fully dissolve and disperse them, forming a precursor solution; then, the precursor solution was stirred and reacted at 100-210 °C under a protective gas atmosphere for 6-45 h, and the product was then separated and washed to obtain a covalent organic framework (COF), denoted as SNW-1; (2) SNW-1 obtained in step (1) was added to acetonitrile and sonicated to fully disperse it, then 1,3-propanesulfonic acid lactone was added, and the mixture was stirred and reacted at 30-100 °C under a protective gas atmosphere for 10-30 h. h; then the product is separated and cleaned to obtain zwitterionic functionalized covalent organic framework, denoted as ZSNW-1; (3) the surfactant and catalyst are dissolved in deionized water and stirred thoroughly to form solution A; the silicon precursor is dissolved in a mixture of co-surfactant and organic solvent and stirred thoroughly to form solution B; then, solution A is added to solution B and stirred thoroughly to form reaction stock solution, and the reaction solution is transferred to a flask and refluxed at 30 ~ 100 ℃ for 10 ~ 30 h; then the product is separated and cleaned to obtain SiO2 nanospheres; (4) ZSNW-1 obtained in step (2) and SiO2 nanospheres obtained in step (3) are added to sulfonated polymer solution at a mass ratio of 2:1, and ultrasonically treated to obtain uniformly dispersed casting solution; then, the casting solution is used to form membrane material, and after drying, it is soaked in hydrogen peroxide solution, acid and deionized water in sequence to obtain a polymer hybrid proton exchange membrane synergistically modified by zwitterionic functionalized covalent organic framework COF and SiO2 nanospheres.

2. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of melamine to terephthalaldehyde is 1:0.5 to 1:6; the protective gas is either nitrogen or argon.

3. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of SNW-1 to 1,3-propanesulfonic acid lactone is 1:3 to 1:7; the protective gas is either nitrogen or argon.

4. The preparation method according to claim 1, characterized in that, In step (3), the catalyst is one or a mixture of several of urea, ammonia, NaOH solution, and triethanolamine (TEA); the surfactant is one or a mixture of several of hexadecyltrimethylammonium bromide (CTAB), octadecyltrimethylammonium bromide (OTAB), sodium dodecylbenzenesulfonate (SDBS), and hexadecyltrimethylammonium chloride (CTAC); the co-surfactant is one or a mixture of several of isopropanol, butanol, and n-pentanol; the silicon precursor is one or a mixture of several of tetraethyl orthosilicate (TEOS) and 1,2-bis(triethoxysilyl)ethane (BTSE); and the organic solvent is one or a mixture of several of cyclohexane and toluene.

5. The preparation method according to claim 1, characterized in that, In step (4), the sum of the amounts of ZSNW-1 and SiO2 nanospheres added accounts for 0.4 to 2.2 wt% of the mass of the sulfonated polymer matrix.

6. The preparation method according to claim 5, characterized in that, In step (4), the sum of the amounts of ZSNW-1 and SiO2 nanospheres added accounts for 1.0 to 1.4 wt% of the mass of the sulfonated polymer matrix.

7. The preparation method according to claim 1, characterized in that, In steps (1), (2), and (3), the solvent used for cleaning is independently selected from one or a mixture of several of CH3OH, C2H5OH, CHCl3, CH2Cl2, CH3Cl, acetone, butanone, and tetrahydrofuran.

8. The preparation method according to claim 1, characterized in that, In step (4), the sulfonated polymer solution is one of the following: a homogeneous solution of perfluorosulfonic acid resin, sulfonated polyether ether ketone, sulfonated polybenzimidazole, sulfonated polyether sulfone, or sulfonated polyimide; the concentration of the sulfonated polymer solution is 1 to 40 wt%; the membrane material is formed by using the casting solution, specifically by coating the casting solution into a membrane; the drying involves placing the membrane material in an oven at 50 to 80 ℃, heating it to 110 to 150 ℃, and then maintaining it for 12 to 36 h; the heating rate is less than 0.5 ℃ / min.

9. The preparation method according to claim 1, characterized in that, In step (4), the sulfonated polymer solution is one of the following: a homogeneous solution of perfluorosulfonic acid resin, sulfonated polyether ether ketone, sulfonated polybenzimidazole, sulfonated polyether sulfone, or sulfonated polyimide; the concentration of the sulfonated polymer solution is 1 to 40 wt%; the membrane material is formed by using the casting solution, specifically by coating the casting solution into a membrane; the drying involves placing the membrane material in an oven at 50 to 80 ℃, heating it to 110 to 150 ℃, and then maintaining it for 12 to 36 h; the heating rate is 0.1 to 0.5 ℃ / min.

10. The preparation method according to claim 1, characterized in that, In step (4), the concentration of the hydrogen peroxide solution is 1 ~ 10 wt%; the acid solution is specifically a mixture of one or more of hydrochloric acid, sulfuric acid, and phosphoric acid, and the concentration of the acid solution is 0.1 ~ 4 mol / L.

11. A zwitterionic functionalized COF and SiO2 nanosphere synergistically modified polymer hybrid proton exchange membrane prepared by the preparation method according to any one of claims 1-10.

12. The application of the zwitterionic functionalized COF and SiO2 nanosphere synergistically modified polymer hybrid proton exchange membrane as described in claim 11 in proton exchange membrane fuel cells.

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