A pom-guanidine salt hydrogen bond material with super-high proton conductivity and a preparation method and application thereof

Abstract

This invention belongs to the field of hydrogen-bonded material preparation, and discloses a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, its preparation method, and its applications. The POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity is self-assembled by multiple repeating units in three-dimensional space through a hydrogen bond network. The chemical formula of each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O 40 The compound [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdate anion, and seven lattice water molecules. Its preparation method involves dissolving 4-guanidinobenzoic acid salt and phosphomolybdate hydrate in deionized water at a molar ratio of 1:3 to 3:1, followed by a hydrothermal reaction to obtain a POM-guanidinocyanate hydrogen-bonded material with ultra-high proton conductivity. Its application is as a proton exchange membrane in proton exchange membrane fuel cells. The POM-guanidinocyanate hydrogen-bonded material of this invention possesses both ultra-high stability and high proton conductivity; the preparation method is simple and easy to implement; and its application prospects are broad.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen bond material preparation technology, and relates to a POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity, its preparation method and application. Background Technology

[0002] With the continuous growth of global energy consumption and the dwindling reserves of fossil fuels, human society is facing a severe energy crisis and environmental pollution problems. Proton exchange membrane fuel cells (PEMFCs), as a clean energy device that directly converts chemical energy into electrical energy, are considered one of the effective ways to solve energy and environmental problems due to their advantages such as low operating temperature, high energy conversion efficiency, and high power density. However, the commercial application of PEMFCs still faces many challenges, one of the core issues being the performance bottleneck of proton conducting materials.

[0003] Proton conduction materials are a key component of proton exchange membrane fuel cells, and their performance directly determines the efficiency and stability of the fuel cell. However, existing proton conduction materials often suffer from low conduction efficiency and poor stability. This deficiency severely limits the application of fuel cells under a wider range of operating conditions, especially in scenarios requiring high-temperature operation.

[0004] Hydrogen-bonded organic frameworks (HOFs) are a new class of porous crystalline materials that self-assemble into networks with periodic structures through intermolecular hydrogen bonding. Compared with traditional metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), HOFs have unique advantages: First, the dynamic reversibility of hydrogen bonds endows HOFs with excellent solution processability and self-healing capabilities; second, HOFs can be regenerated through a simple recrystallization process, exhibiting good recyclability; furthermore, the flexibility and tunability of the hydrogen bond network enable HOFs to respond to external stimuli (such as temperature, humidity, pH, etc.), exhibiting structurally adaptive properties.

[0005] Polyoxometalates (POMs) are typical anionic clusters assembled from XO4 anions (X = Mo, W, V, Nb, Ta, etc.). Because these clusters are composed entirely of inorganic elements, they possess inherent structural rigidity. Simultaneously, the numerous oxygen atoms covering their surfaces provide abundant active sites for hydrogen bonding. These properties make POMs suitable as novel building blocks for constructing hydrogen-bonded organic frameworks. However, when POM clusters are combined with substances such as ammonium (NH4+)... 4+ ), Amidone (RNH) 2+ guanidine (RNH) 3+When cations such as POMs combine, the strong electrostatic interactions between them often result in a tight framework structure. This dense structure severely restricts the migration of internal protons, making it difficult to form continuous, long-range proton transport channels within the framework, thus greatly limiting the proton conductivity of the material. Therefore, how to construct polyacid-based organic framework materials with high proton conductivity by carefully selecting and matching POMs with organic counterions remains a significant challenge in the current research field.

[0006] To address these issues, existing technologies introduce organic bases with weak electrostatic interactions in the protonated state and employ strategies that provide abundant hydrogen bond donors. Nevertheless, constructing a strongly hydrogen-bonded POM-organic framework with high proton conductivity through careful selection and matching of suitable POMs and counterions remains a challenging task.

[0007] For example, the traditional pure organic HOFs prepared in Reference 1 (Anhydrous Solid-State Proton Conduction in Crystalline MOFs, COFs, HOFs, and POMs[J]. Journal of the American Chemical Society, 2025, 147(7): 5515-5553.) and Reference 2 (Multifunctional Porous Hydrogen-Bonded Organic Frameworks: Current Status and Future Perspectives[J]. ACS Central Science, 2022, 8(12):1589-1608.) have relatively weak intermolecular hydrogen bond energies (usually only 10~40 kJ mol). -1 Furthermore, lacking intrinsic proton donors, it is highly susceptible to framework collapse under harsh conditions such as solvent removal or high humidity and strong acid required for fuel cells, which severely limits its proton conduction performance.

[0008] Existing technologies also utilize POMs to construct HOFs, for example, in reference 3 (Proton transfer in polyamine–P2Mo5 model adducts: exploring the effect of polyamine cations on their proton conductivity[J]. Dalton TransactionsThe study, 2020, 49(48), 17301–17309, mainly investigated an organic-inorganic hybrid system assembled from different polyamine cations (triethylenetetramine (TETA), diethylenetriamine (DETA), and ethylenediamine (EN)) and polyacid anions (P2Mo5) through electrostatic and hydrogen bonding interactions. In this system, the P2Mo5-EN adduct exhibited the best proton conductivity (1.13 × 10⁻⁶) at 65 °C and 95% relative humidity (RH). -2 Scm -1 Its proton transfer follows the Grotthuss (jumping) mechanism. However, TETA, DETA, and EN used in the literature are all flexible linear aliphatic polyamines, lacking a rigid supporting framework in physical space. Due to the extremely strong electrostatic attraction between the high negative charge density POM anions and cations, this system, which relies purely on short-range hydrogen bonds and electrostatic maintenance, is prone to network distortion and restructuring and structural collapse when heated or when the free solvent is removed. Therefore, its highest test temperature is only 65 °C.

[0009] Document 4 (Polyoxometalate-based hydrogen-bonded organic frameworks as a new class of proton conducting materials[J]. CrystEngComm In 2020, 22(47), 8161–8165, a POM-based hydrogen-bonded organic framework material (PHOF 1) was reported, constructed by the self-assembly of Keggin-type polyoxometalate phosphomolybdic acid and 2-phenyl-1H-imidazolium. This material exhibited good water, chemical, and thermal stability, but its highest proton conductivity was only 2.02 × 10⁻⁶ at 98% relative humidity and 100 °C. -4 S cm -1 Furthermore, proton transport primarily relies on the synergy of transport and hopping mechanisms, and its high activation energy (0.44~0.54 eV) limits its practical application efficiency in high-performance fuel cells. However, the functional groups of ligands (such as imidazole groups) are mainly linked by simple NH…O hydrogen bonds, resulting in weak anchoring ability for lattice water molecules. Under high humidity or high temperature desolventizing conditions, the distribution of water molecules easily becomes disordered or fragmented, leading to increased proton transport resistance.

[0010] Therefore, it is of great significance to study a POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity, its preparation method and application, in order to solve the above problems. Summary of the Invention

[0011] The purpose of this invention is to address the problems existing in the prior art and to provide a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, its preparation method, and its application.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] A POM-guanidinium hydrogen-bonded material with ultra-high proton conductivity is formed by the self-assembly of multiple repeating units in three-dimensional space through a highly ordered hydrogen bond network. The chemical formula of each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O 40 [C8N3O2H9]·7H2O contains 3 4-guanidinobenzoic acid cations, 1 neutral 4-guanidinobenzoic acid molecule, 1 phosphomolybdate anion, and 7 lattice water molecules; The thermal stability temperature of POM-guanidinium hydrogen-bonded materials with ultra-high proton conductivity is 220–280 °C; the proton conductivity at 90 °C and 98% relative humidity is 1.5 × 10⁻⁶. -2 ~2.0×10 -2 S cm -1 The activation energy Ea is 0.25~0.30 eV.

[0014] As a preferred technical solution:

[0015] As described above, a POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity has repeating units (i.e., structural units) belonging to the monoclinic crystal system, space group P21 / c, and molecular formula C. 32 H 53 Mo 12 N 12 O 55 P, cell parameters: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, V (cell volume) = 6898.6(16) Å 3 .

[0016] As described above, a POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity has four 4-guanidinium benzoate ligands surrounding a phosphomolybdic acid in each repeating unit. The 4-guanidinium benzoate ligands (three 4-guanidinium benzoate cations and one neutral 4-guanidinium benzoate molecule) act as hydrogen bond donors and are connected to the terminal oxygen and bridging oxygen (referring to the oxygen atom in the middle of Mo-O-Mo of phosphomolybdic acid) and the lattice water molecules through NH···O bonds and CH···O bonds, thereby forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds.

[0017] The present invention also provides a method for preparing a POM-guanidine salt hydrogen bond material with ultra-high proton conductivity as described above, wherein 4-guanidine benzoate salt and phosphomolybdic acid hydrate are dissolved in deionized water at a molar ratio of 1:3 to 3:1, and then a hydrothermal reaction is carried out to obtain a POM-guanidine salt hydrogen bond material with ultra-high proton conductivity.

[0018] As a preferred technical solution:

[0019] The preparation method of the POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity as described above involves a hydrothermal reaction carried out in a hydrothermal reactor containing polytetrafluoroethylene, at a reaction temperature of 140~160℃, and for a reaction time of 3~5 days.

[0020] The preparation method of a POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity as described above involves cooling the temperature to 25~45℃ after the hydrothermal reaction to obtain black-blue crystals, which are then washed and dried multiple times with ethanol.

[0021] The present invention also provides the application of a POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity as described above, as a proton exchange membrane in a proton exchange membrane fuel cell.

[0022] Invention principle:

[0023] In existing technologies, hydrogen-bonded organic frameworks are mainly classified according to the hydrogen-bonded building blocks on their organic ligands. Classic examples include: carboxylic acid HOFs, which spontaneously assemble into highly crystalline three-dimensional networks through highly directional charge-assisted hydrogen bonding between carboxylic acids and nitrogen-containing heterocyclic ligands; diaminotriazine HOFs, which utilize NH...N hydrogen bonds between diaminotriazines to form stable structural units; sulfonic acid HOFs, which form stable three-dimensional supramolecular frameworks through directional self-assembly of strongly acidic sulfonic acid ligands and amine basic ligands, using charge-assisted (or acid-base) multiple hydrogen-bonded networks; and charge-assisted (ionic) HOFs, which enhance stability through strong electrostatic interactions, such as the guanidinium sulfonate (GS) framework, which uses C(NH2) bonds... 3+The NH···O charge-assisted hydrogen bond formation between R-SO3- and R-SO3-. Existing HOFs often suffer from weak hydrogen bond strength or a lack of rigid spatial physical support, leading to pore collapse upon solvent removal or heating. This pore collapse not only directly destroys the structural integrity of the material (resulting in poor thermal stability), but more seriously, it locks up the internal pores, severing the continuous hydrogen bond network and water molecule channels that normally support proton transport. Macroscopically, this leads to a sharp increase in proton transport resistance and high activation energy, resulting in low conductivity and structural degradation and collapse under high-temperature and high-humidity fuel cell operating conditions.

[0024] To address the aforementioned problems in existing technologies, this invention proposes a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity. This material is a three-dimensional supramolecular polymer linked by non-covalent bonds, wherein each repeating unit has the chemical formula [C8N3O2H]. 10 ]3·[PMo 12 O 40 The compound [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdic acid anion, and seven lattice water molecules. Utilizing the numerous terminal and bridging oxygen sites on the phosphomolybdic acid surface, it forms multiple hydrogen bonds (NH···O, CH···O) and electrostatic interactions with the 4-guanidinobenzoic acid ligand, constructing a three-dimensional framework structure with both high crystallinity and high thermal stability. First, the three 4-guanidinobenzoic acid cations not only provide charge neutralization, but their unique benzene rings and carboxyl groups also provide significant steric hindrance, physically widening the distance between the phosphomolybdic acid molecules. Second, the seven lattice water molecules fill the widened space, forming a three-dimensional hydrogen bond network with the 4-guanidinobenzoic acid ligand and phosphomolybdic acid. In this interlocked three-dimensional hydrogen bond network, protons do not need to carry water molecules on long journeys. They only need to make "jumps" between adjacent reactive oxygen atoms and ordered water chains with extremely low energy consumption, thus achieving ultra-high conduction efficiency and extremely low activation energy.

[0025] Existing technologies (such as GH-PMo) 12 Although the introduction of phosphomolybdic acid and protonated guanidinium (C(NH2)3) has also been disclosed +However, ordinary guanidinium cations have two inherent defects: first, the pure guanidinium molecule is small in size, and when it combines with POM anions with high negative charge density, the anions and cations will be extremely densely packed due to the strong electrostatic attraction; second, the pure guanidinium can only provide NH···O hydrogen bonds in a single region. When the material is heated or the lattice solvent is removed, this short-range hydrogen bond network without skeletal support is very easy to be twisted and reorganized, resulting in instantaneous dense packing of the structure. The core inventiveness of this invention lies in abandoning the traditional small molecule guanidinium and creatively introducing a composite double-terminal rigid ligand (4-guanidinium benzoate) that has both "guanidinium-benzene ring-carboxyl group". These three basic units play an irreplaceable synergistic "anti-collapse" role in three-dimensional space: (1) Strong charge-assisted hydrogen bond end (guanidinium end): The protonated guanidinium end contains abundant amino groups (-NH2, -NH), which act as strong hydrogen bond donors and form multiple charge-assisted hydrogen bonds (NH···O) with a large number of terminal oxygen and bridging oxygen on the surface of phosphomolybdic acid. (2) Rigid physical support (benzene ring core): Its huge steric hindrance physically forces the distance between adjacent phosphomolybdic acids, fundamentally blocking the close packing of phosphomolybdic acids. In addition, the carbon-hydrogen bonds on the benzene ring can also form extensive CH···O weak hydrogen bonds with oxygen on polyacids, further locking the spatial conformation of the ligand. (3) Extended cross-linking end (carboxylic acid group): The carboxyl group (-COOH) at the other end of the ligand is both a hydrogen bond donor and acceptor. It can not only form strong OH···O hydrogen bonds with lattice water molecules, but also cross-link with other ligands. This double-end connection mode makes the ligand form a connection channel between two phosphomolybdic acids or between phosphomolybdic acid and water. In summary, the existing POM-guanidinium salt materials are often just simple "cation and anion salts" stacking; while the present invention relies on the unique "double-end multi-point anchoring + central rigid support" mechanism of 4-guanidinium benzoate ligand to construct a strong interlocking three-dimensional network structure.

[0026] Beneficial effects:

[0027] (1) The POM-guanidinium hydrogen bond material of the present invention interacts with phosphomolybdic acid and 4-guanidinium benzoate ligand. At the same time, when the 4-guanidinium benzoate ligand is protonated, it brings appropriate electrostatic effect, as well as a weak organic base and abundant hydrogen bond donors, thereby forming a framework material.

[0028] (2) The POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity prepared by the present invention has a three-dimensional framework that facilitates proton transport and has ultra-high stability. Powder X-ray diffraction (PXRD) analysis data shows that the obtained product has high purity, thermogravimetric analysis shows high thermal stability, and it also has high proton conductivity. It is a new type of proton conductive material and has good application prospects as a proton conductive material.

[0029] (3) The POM-guanidinium hydrogen bond material with ultra-high proton conductivity of the present invention is prepared by 4-guanidinium benzoate and phosphomolybdic acid hydrate. The raw materials are readily available, and the crystals are grown by hydrothermal method. The preparation process is simple, easy to operate, and has a high yield.

[0030] (4) This invention not only completely makes up for the shortcomings of poor stability of traditional HOFs, but also interweaves the abundant protons of inorganic superacids with long-range ordered hydrogen bond networks to construct a low activation energy proton transport channel within the framework structure, thereby endowing the material with ultra-high proton conductivity under complex conditions. Attached Figure Description

[0031] Figure 1 This is an asymmetric unit diagram of the POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity of the present invention; Figure 2 This is a two-dimensional (2D) hydrogen bond network structure diagram of the POM-guanidinium hydrogen bond material with ultra-high proton conductivity of the present invention; Figure 3 The diagram shows the three-dimensional (3D) hydrogen bond network structure of the POM-guanidinium hydrogen bond material with ultra-high proton conductivity of the present invention; in the diagram, (1) is a schematic diagram of the stacking along the a-axis, and (2) is a schematic diagram of the stacking along the b-axis. Figure 4 This is a comparison between the powder X-ray diffraction pattern of the POM-guanidinium hydrogen bond material with ultra-high proton conductivity prepared in Example 8 of the present invention and the powder X-ray diffraction pattern simulated by single crystal data. Figure 5 Thermogravimetric analysis diagram of the POM-guanidinium salt hydrogen bonded material with ultra-high proton conductivity prepared in Example 8 of the present invention; Figure 6 The electrochemical impedance spectroscopy of the POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity prepared in Example 8 of this invention; Figure 7 The diagram shows the activation energy of the POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity prepared in Example 8 of this invention. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0033] The manufacturers and brands mentioned in the following embodiments are merely examples. The core of this invention lies in the technical solution itself, and it is not intended to limit specific manufacturers or brands. Products from other manufacturers and brands that meet the technical requirements and performance indicators specified in this invention can also meet the application requirements of this invention and are all feasible choices.

[0034] The test methods for the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0035] The pure crystals were ground into a uniform powder. 50 mg of the sample was placed in a 5 mm diameter circular tableting mold and compressed for 10 minutes at 10 MPa using a tablet press, forming tablets with a thickness of 0.1 cm and an area of ​​0.196 cm². 2 Thin slices were used as samples for testing proton conductivity and activation energy Ea, as detailed below:

[0036] Proton conductivity: The sample was tested using a Chenhua electrochemical workstation at 90℃ and 98% relative humidity. The impedance data measured from the sample was then fitted with an equivalent circuit using Zview software to plot a Nyquist curve. Finally, the proton conductivity of the sample was calculated based on the obtained data. σ (Unit: S·cm) -1 The formula for calculating its proton conductivity is: In the formula, d The thickness (cm) of the sample disc. A The surface area of ​​a circular thin sheet (cm²) 2 ), R The resistance value ( ).

[0037] Activation energy Ea: Based on the sample data measured above and the plotted Nyquist curve, the activation energy Ea of the sample is calculated using the following formula: In the formula, σ 0 Pre-exponential factor, Ea The activation energy is (eV). k B Boltzmann's constant, T is the thermodynamic temperature (K).

[0038] Example 1

[0039] A method for preparing a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, comprising the following steps: (1) Dissolve 4-guanidinobenzoate and phosphomolybdic acid hydrate (manufacturer: Shanghai Titan Technology Co., Ltd., brand: Adamas, CAS No.: 51429-74-4) in deionized water at a molar ratio of 1:1 to obtain a mixed solution; wherein, the concentration of 4-guanidinobenzoate is 0.017 mol / L; (2) The mixed solution was placed in a hydrothermal reactor containing polytetrafluoroethylene and reacted for 3 days at a reaction temperature of 140°C. After the reaction was completed, the temperature was cooled to 25°C to obtain black-blue crystals. After washing and drying with ethanol three times, POM-guanidine salt hydrogen bond material with ultra-high proton conductivity was obtained.

[0040] The obtained POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity is self-assembled by multiple repeating units in three-dimensional space through a highly ordered hydrogen bond network. Each repeating unit belongs to the monoclinic crystal system with space group P21 / c. The unit cell parameters are: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, and V (unit cell volume) = 6898.6(16) Å. 3 ; The chemical formula for each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O 40 [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdate anion, and seven lattice water molecules. The 4-guanidinobenzoic acid ligand acts as a hydrogen bond donor, connecting not only to the terminal oxygen and bridging oxygen of phosphomolybdate through NH···O and CH···O bonds, but also to the lattice water molecules, thus forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds. The aforementioned POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity was placed on a single-crystal X-ray diffractometer for diffraction, and diffraction data were collected. Then, the collected diffraction data was analyzed and refined using the crystallography software Olex2 to determine the three-dimensional spatial coordinates of each atom (Mo, P, O, C, N, H, etc.) within the unit cell. Finally, a CIF file containing crystal structure information (building units) was generated. After obtaining the CIF file, it was imported into the professional crystal visualization software Diamond to plot, as shown... Figures 1-3 The structural diagram shown; The POM-guanidinium hydrogen-bonded material exhibits ultra-high proton conductivity with a thermal stability temperature of 220℃; its proton conductivity at 90℃ and 98% relative humidity is 1.5 × 10⁻⁶. -2 S cm -1 The activation energy Ea is 0.25 eV.

[0041] The aforementioned POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity has good proton conduction performance and can be used as a proton exchange membrane in proton exchange membrane fuel cells.

[0042] Example 2.

[0043] A method for preparing a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, comprising the following steps: (1) Dissolve 4-guanidinobenzoate and phosphomolybdic acid hydrate (manufacturer: Shanghai Titan Technology Co., Ltd., brand: Adamas, CAS No.: 51429-74-4) in deionized water at a molar ratio of 1:1 to obtain a mixed solution; wherein, the concentration of 4-guanidinobenzoate is 0.017 mol / L; (2) The mixed solution was placed in a hydrothermal reactor containing polytetrafluoroethylene and reacted for 4 days at a reaction temperature of 140°C. After the reaction was completed, the temperature was cooled to 25°C to obtain black-blue crystals. After washing and drying with ethanol three times, POM-guanidine salt hydrogen bond material with ultra-high proton conductivity was obtained.

[0044] The obtained POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity is self-assembled by multiple repeating units in three-dimensional space through a highly ordered hydrogen bond network. Each repeating unit belongs to the monoclinic crystal system with space group P21 / c. The unit cell parameters are: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, and V (unit cell volume) = 6898.6(16) Å. 3 ; The chemical formula for each repeating unit is [C8N3O2H].10 ]3·[PMo 12 O 40 [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdate anion, and seven lattice water molecules. The 4-guanidinobenzoic acid ligand acts as a hydrogen bond donor, connecting not only to the terminal oxygen and bridging oxygen of phosphomolybdate through NH···O and CH···O bonds, but also to the lattice water molecules, thus forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds.

[0045] The POM-guanidinium hydrogen-bonded material exhibits ultra-high proton conductivity with a thermal stability temperature of 250℃; its proton conductivity at 90℃ and 98% relative humidity is 1.8 × 10⁻⁶. -2 S cm -1 The activation energy Ea is 0.28 eV.

[0046] The aforementioned POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity has good proton conduction performance and can be used as a proton exchange membrane in proton exchange membrane fuel cells.

[0047] Example 3

[0048] A method for preparing a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, comprising the following steps: (1) Dissolve 4-guanidinobenzoate and phosphomolybdic acid hydrate (manufacturer: Shanghai Titan Technology Co., Ltd., brand: Adamas, CAS No.: 51429-74-4) in deionized water at a molar ratio of 1:1 to obtain a mixed solution; wherein, the concentration of 4-guanidinobenzoate is 0.017 mol / L; (2) The mixed solution was placed in a hydrothermal reactor containing polytetrafluoroethylene and reacted for 5 days at a reaction temperature of 140°C. After the reaction was completed, the temperature was cooled to 25°C to obtain black-blue crystals. After washing and drying with ethanol three times, POM-guanidine salt hydrogen bond material with ultra-high proton conductivity was obtained.

[0049] The obtained POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity is self-assembled by multiple repeating units in three-dimensional space through a highly ordered hydrogen bond network. Each repeating unit belongs to the monoclinic crystal system with space group P21 / c. The unit cell parameters are: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, and V (unit cell volume) = 6898.6(16) Å. 3 ; The chemical formula for each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O 40 [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdate anion, and seven lattice water molecules. The 4-guanidinobenzoic acid ligand acts as a hydrogen bond donor, connecting not only to the terminal oxygen and bridging oxygen of phosphomolybdate through NH···O and CH···O bonds, but also to the lattice water molecules, thus forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds.

[0050] The POM-guanidinium hydrogen-bonded material exhibits ultra-high proton conductivity with a thermal stability temperature of 280℃; its proton conductivity at 90℃ and 98% relative humidity is 2.0 × 10⁻⁶. -2 S cm -1 The activation energy Ea is 0.3 eV.

[0051] The aforementioned POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity has good proton conduction performance and can be used as a proton exchange membrane in proton exchange membrane fuel cells.

[0052] Example 4

[0053] A method for preparing a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, comprising the following steps: (1) Dissolve 4-guanidinobenzoate and phosphomolybdic acid hydrate (manufacturer: Shanghai Titan Technology Co., Ltd., brand: Adamas, CAS No.: 51429-74-4) in deionized water at a molar ratio of 1:3 to obtain a mixed solution; wherein, the concentration of 4-guanidinobenzoate is 0.017 mol / L; (2) The mixed solution was placed in a hydrothermal reactor containing polytetrafluoroethylene and reacted for 3 days at a reaction temperature of 150°C. After the reaction was completed, the temperature was cooled to 35°C to obtain black-blue crystals. After washing and drying with ethanol three times, POM-guanidine salt hydrogen bond material with ultra-high proton conductivity was obtained.

[0054] The obtained POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity is self-assembled by multiple repeating units in three-dimensional space through a highly ordered hydrogen bond network. Each repeating unit belongs to the monoclinic crystal system with space group P21 / c. The unit cell parameters are: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, and V (unit cell volume) = 6898.6(16) Å. 3 ; The chemical formula for each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O 40 [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdate anion, and seven lattice water molecules. The 4-guanidinobenzoic acid ligand acts as a hydrogen bond donor, connecting not only to the terminal oxygen and bridging oxygen of phosphomolybdate through NH···O and CH···O bonds, but also to the lattice water molecules, thus forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds.

[0055] The POM-guanidinium hydrogen-bonded material exhibits ultra-high proton conductivity with a thermal stability temperature of 220℃; its proton conductivity at 90℃ and 98% relative humidity is 1.5 × 10⁻⁶. -2 S cm -1 The activation energy Ea is 0.25 eV.

[0056] The aforementioned POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity has good proton conduction performance and can be used as a proton exchange membrane in proton exchange membrane fuel cells.

[0057] Example 5

[0058] A method for preparing a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, comprising the following steps: (1) Dissolve 4-guanidinobenzoate and phosphomolybdic acid hydrate (manufacturer: Shanghai Titan Technology Co., Ltd., brand: Adamas, CAS No.: 51429-74-4) in deionized water at a molar ratio of 1:3 to obtain a mixed solution; wherein, the concentration of 4-guanidinobenzoate is 0.017 mol / L; (2) The mixed solution was placed in a hydrothermal reactor containing polytetrafluoroethylene and reacted for 4 days at a reaction temperature of 150°C. After the reaction was completed, the temperature was cooled to 35°C to obtain black-blue crystals. After washing and drying with ethanol three times, POM-guanidine salt hydrogen bond material with ultra-high proton conductivity was obtained.

[0059] The obtained POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity is self-assembled by multiple repeating units in three-dimensional space through a highly ordered hydrogen bond network. Each repeating unit belongs to the monoclinic crystal system with space group P21 / c. The unit cell parameters are: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, and V (unit cell volume) = 6898.6(16) Å. 3 ; The chemical formula for each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O 40 [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdate anion, and seven lattice water molecules. The 4-guanidinobenzoic acid ligand acts as a hydrogen bond donor, connecting not only to the terminal oxygen and bridging oxygen of phosphomolybdate through NH···O and CH···O bonds, but also to the lattice water molecules, thus forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds.

[0060] The POM-guanidinium hydrogen-bonded material exhibits ultra-high proton conductivity with a thermal stability temperature of 250℃; its proton conductivity at 90℃ and 98% relative humidity is 1.8 × 10⁻⁶. -2 S cm -1 The activation energy Ea is 0.28 eV.

[0061] The aforementioned POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity has good proton conduction performance and can be used as a proton exchange membrane in proton exchange membrane fuel cells.

[0062] Example 6

[0063] A method for preparing a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, comprising the following steps: (1) Dissolve 4-guanidinobenzoate and phosphomolybdic acid hydrate (manufacturer: Shanghai Titan Technology Co., Ltd., brand: Adamas, CAS No.: 51429-74-4) in deionized water at a molar ratio of 1:3 to obtain a mixed solution; wherein, the concentration of 4-guanidinobenzoate is 0.017 mol / L; (2) The mixed solution was placed in a hydrothermal reactor containing polytetrafluoroethylene and reacted for 5 days at a reaction temperature of 150°C. After the reaction was completed, the temperature was cooled to 35°C to obtain black-blue crystals. After washing with ethanol three times and drying, POM-guanidine salt hydrogen bond material with ultra-high proton conductivity was obtained.

[0064] The obtained POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity is self-assembled by multiple repeating units in three-dimensional space through a highly ordered hydrogen bond network. Each repeating unit belongs to the monoclinic crystal system with space group P21 / c. The unit cell parameters are: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, and V (unit cell volume) = 6898.6(16) Å. 3 ; The chemical formula for each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O 40 [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdate anion, and seven lattice water molecules. The 4-guanidinobenzoic acid ligand acts as a hydrogen bond donor, connecting not only to the terminal oxygen and bridging oxygen of phosphomolybdate through NH···O and CH···O bonds, but also to the lattice water molecules, thus forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds.

[0065] The POM-guanidinium hydrogen-bonded material exhibits ultra-high proton conductivity with a thermal stability temperature of 280℃; its proton conductivity at 90℃ and 98% relative humidity is 2.0 × 10⁻⁶. -2 S cm -1 The activation energy Ea is 0.3 eV.

[0066] The aforementioned POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity has good proton conduction performance and can be used as a proton exchange membrane in proton exchange membrane fuel cells.

[0067] Example 7

[0068] A method for preparing a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, comprising the following steps: (1) Dissolve 4-guanidinobenzoate and phosphomolybdic acid hydrate (manufacturer: Shanghai Titan Technology Co., Ltd., brand: Adamas, CAS No.: 51429-74-4) in deionized water at a molar ratio of 3:1 to obtain a mixed solution; wherein, the concentration of 4-guanidinobenzoate is 0.051 mol / L; (2) The mixed solution was placed in a hydrothermal reactor containing polytetrafluoroethylene and reacted for 3 days at a reaction temperature of 160°C. After the reaction was completed, the temperature was cooled to 45°C to obtain black-blue crystals. After washing and drying with ethanol three times, POM-guanidine salt hydrogen bond material with ultra-high proton conductivity was obtained.

[0069] The obtained POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity is self-assembled by multiple repeating units in three-dimensional space through a highly ordered hydrogen bond network. Each repeating unit belongs to the monoclinic crystal system with space group P21 / c. The unit cell parameters are: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, and V (unit cell volume) = 6898.6(16) Å. 3 ; The chemical formula for each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O40 [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdate anion, and seven lattice water molecules. The 4-guanidinobenzoic acid ligand acts as a hydrogen bond donor, connecting not only to the terminal oxygen and bridging oxygen of phosphomolybdate through NH···O and CH···O bonds, but also to the lattice water molecules, thus forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds.

[0070] The POM-guanidinium hydrogen-bonded material exhibits ultra-high proton conductivity with a thermal stability temperature of 220℃; its proton conductivity at 90℃ and 98% relative humidity is 1.5 × 10⁻⁶. -2 S cm -1 The activation energy Ea is 0.25 eV.

[0071] The aforementioned POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity has good proton conduction performance and can be used as a proton exchange membrane in proton exchange membrane fuel cells.

[0072] Example 8

[0073] A method for preparing a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, comprising the following steps: (1) Dissolve 4-guanidinobenzoate and phosphomolybdic acid hydrate (manufacturer: Shanghai Titan Technology Co., Ltd., brand: Adamas, CAS No.: 51429-74-4) in deionized water at a molar ratio of 3:1 to obtain a mixed solution; wherein, the concentration of 4-guanidinobenzoate is 0.051 mol / L; (2) The mixed solution was placed in a hydrothermal reactor containing polytetrafluoroethylene and reacted for 4 days at a reaction temperature of 160°C. After the reaction was completed, the temperature was cooled to 45°C to obtain black-blue crystals. After washing and drying with ethanol three times, POM-guanidine salt hydrogen bond material with ultra-high proton conductivity was obtained.

[0074] The obtained POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity is self-assembled by multiple repeating units in three-dimensional space through a highly ordered hydrogen bond network. Each repeating unit belongs to the monoclinic crystal system with space group P21 / c. The unit cell parameters are: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, and V (unit cell volume) = 6898.6(16) Å. 3 ; The chemical formula for each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O 40 [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdate anion, and seven lattice water molecules. The 4-guanidinobenzoic acid ligand acts as a hydrogen bond donor, connecting not only to the terminal oxygen and bridging oxygen of phosphomolybdate through NH···O and CH···O bonds, but also to the lattice water molecules, thus forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds.

[0075] The POM-guanidinium hydrogen-bonded material exhibits ultra-high proton conductivity with a thermal stability temperature of 250℃; its proton conductivity at 90℃ and 98% relative humidity is 1.8 × 10⁻⁶. -2 S cm -1 The activation energy Ea is 0.286 eV; To comprehensively evaluate the physicochemical properties and proton conductivity of the aforementioned POM-guanidinium hydrogen-bonded materials with ultra-high proton conductivity, thermogravimetric analysis was first performed. The results are as follows: Figure 5 As shown in the figure, between 25°C and 150°C, only a slight weight loss of 5% occurred due to the volatilization of physically adsorbed guest molecules (such as free water or residual solvent) in the pores; the curve then showed a clear plateau period, indicating that it has excellent thermal stability up to 250°C, and only after exceeding this temperature does the organic ligand undergo thermal degradation and cause the framework to collapse. Based on the good structural stability of the sample, its AC impedance was tested at 98% relative humidity (RH) over a temperature range of 30°C to 90°C. The results are as follows: Figure 6 As shown, the results revealed that its proton conductivity exhibits a significant temperature dependence, reaching 1.8 × 10⁻⁶ at a temperature of 90°C and a relative humidity of 98%. -2 S cm -1 The calculated activation energy for conduction is 0.286 eV (e.g., ...). Figure 7 As shown in the figure, this extremely low energy barrier strongly demonstrates that a highly interconnected continuous hydrogen bond network is constructed inside the material, in which the long-range transport of protons mainly follows the grothuss mechanism, that is, efficient hopping is achieved through the rapid formation and breaking of hydrogen bonds.

[0076] The aforementioned POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity has good proton conduction performance and can be used as a proton exchange membrane in proton exchange membrane fuel cells.

[0077] To verify the structural consistency of the bulk material, powder X-ray diffraction (PXRD) tests were performed on the aforementioned POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity. The results are as follows: Figure 4 As shown in the figure, the PXRD pattern of the prepared POM-guanidinium hydrogen bond material with ultra-high proton conductivity is highly consistent with the pattern simulated based on single crystal structure data. This not only confirms that the three-dimensional hydrogen bond network structure was successfully prepared in this embodiment, but also shows that the synthesized POM-guanidinium hydrogen bond material with ultra-high proton conductivity has extremely high crystallinity and pure phase characteristics.

[0078] Comparative Example 1

[0079] A method for preparing HOF-H3L (carboxylic acid HOFs) includes the following steps: (1) At 25°C, 1.33 mL of p-methylbenzoyl chloride (10 mmol) was added dropwise to 25 mL of acetonitrile solution containing 1.0 g of anhydrous potassium thiocyanate (10 mmol). After stirring the solution for 1 hour, 0.75 g of aminoacetic acid (10 mmol) was added. The resulting mixture was heated under reflux for 6.5 hours and then cooled to 25°C. The resulting yellow mixture was then poured into 300 mL of ice water. The pale yellow solid was collected by filtration and dried in air to obtain H3L. (2) Dissolve 200 mg of H3L in a mixed solution of methanol and water (volume ratio 2:1, 20 mL), and then let the solution stand at 25 °C to allow it to evaporate naturally. After three days, collect pale yellow needle-like crystals to obtain pure phase HOF-H3L single crystals.

[0080] The prepared HOF-H3L is formed by the free carboxylic acid terminus (-COOH), carbonyl group (C=O) and thiourea group (-NH-C=S-NH-) of the ligands being connected and spontaneously assembled through high-strength intermolecular NH···O hydrogen bonds and OH···O hydrogen bonds, forming a three-dimensional (3D) supramolecular hydrogen bond network without metal ions. Its lattice has micropores that can adsorb trace amounts of guest water molecules. The thermal stability temperature of HOF-H3L is 180℃; its proton conductivity at 90℃ and 98% relative humidity is 2.15 × 10⁻⁶. -5 S cm -1 The activation energy Ea is 0.72 eV.

[0081] Comparing Comparative Example 1 and Example 8, it can be seen that although the HOF-H3L prepared in this comparative example relies on the free carboxylic acid groups within the framework as intrinsic proton sources to initiate proton conduction, its conductivity under high temperature and high humidity is extremely weak. The core reasons are as follows: First, the lack of coordinated water molecules brought by metal nodes in the pure hydrogen bond network channels makes it difficult for the adsorbed guest water molecules to anchor within the channels and form a dense, continuous long-range water molecule cluster network. The distance between proton donors is too far, making it impossible to efficiently excite the low-barrier Grotthuss (proton relay) transport mechanism. Second, the main framework, which relies entirely on non-covalent weak bonds (hydrogen bonds) for maintenance, is prone to microscopic structural oscillations under high temperature of 90°C and saturated high humidity of 98%. The large influx of water molecules causes some hydrogen bonds in the original framework to break or recombine, destroying the steady-state physical channels for proton transport. This significantly increases the energy barrier when protons cross molecular gaps, thus severely limiting the overall upper limit of its proton conduction performance.

[0082] Comparative Example 2

[0083] A method for preparing HOF-6 (diaminotriazine HOFs) includes the following steps: (1) Dissolve 25 mg of 5,10,15,20-tetrakis(4-(2,4-diaminotriazinyl)phenyl)porphyrin (H2TDPP) completely in 2 mL of N,N-dimethylformamide, and then filter. (2) Tetrahydrofuran was slowly spread on the upper layer of the filtrate in a sealed tube. After one week, as the tetrahydrofuran slowly diffused into the N,N-dimethylformamide solution of H2TDPP, HOF-6 purple single crystals were obtained, which is HOF-6.

[0084] The prepared HOF-6 is a two-dimensional layered network with abundant free amino sites, formed by the assembly and cross-linking of carboxylic acid groups and diaminotriazine groups through strong NH···O and OH···N multi-charge-assisted hydrogen bonds. HOF-6 has a thermal stability temperature of 210℃; its proton conductivity at 90℃ and 98% relative humidity is 4.50 × 10⁻⁶. -3 S cm -1 .

[0085] Comparing Comparative Example 2 and Example 8, it can be seen that although the conductivity of HOF-6 prepared in this comparative example is improved by acid-base proton pairs, its thermal stability and overall performance limit are still lower than those of Example 8. This is because it is formed by standing at room temperature (25°C), the synthesis conditions are relatively mild, and its main framework relies on weak non-covalent bonds, which makes it easy for some hydrogen bond networks to rearrange or break locally under high temperature and high humidity conditions, thereby damaging the continuity of proton transport channels and reducing thermal stability.

[0086] Comparative Example 3

[0087] A method for preparing NKM-HOF-10 (sulfonic acid HOFs) includes the following steps: (1) Add 6.00 mL of acetone to 15.7 mg (0.05 mmol) of 4,4-biphenyl disulfonic acid and filter to obtain a 4,4-biphenyl disulfonic acid solution; (2) Add 6.00 mL of acetone to 13.6 mg (0.10 mmol) of p-phenylenediamine, filter, and obtain a p-phenylenediamine solution; (3) After mixing the 4,4-biphenyl disulfonic acid solution prepared in step (1) with the p-phenylenediamine solution prepared in step (2) evenly, filter the mixture to obtain white powder crystals, which is NKM-HOF-10.

[0088] The prepared NKM-HOF-10 is cross-linked by aromatic disulfonic acid groups and amine hydrogen bond donors through non-covalent interactions, forming a two-dimensional multi-component hydrogen bond network structure with continuous channels. The proton conductivity of NKM-HOF-10 at 85 °C and 98% relative humidity is 1.7 × 10⁻⁶. -3 S cm -1 The activation energy Ea is 0.22 eV.

[0089] Comparing Comparative Example 3 and Example 8, it can be seen that the proton conductivity of NKM-HOF-10 prepared in this comparative example is relatively low. This is because the channel constructed purely by amine donors is not as dense as the cooperative hydrogen bond network assembled in the examples, and the number of continuous sites for proton hopping is limited.

[0090] Comparative Example 4

[0091] A method for preparing iHOF-37 (ionic form) includes the following steps: Bis(benzene-o-sulfonic acid)naphthalimide (9.15 mg, 0.0158 mmol) and 1,1′-diamino-4,4′-bipyridine diiodide (DBpy·2I) (7 mg, 0.0155 mmol) were dissolved in dimethyl sulfoxide (3 mL) and dimethyl sulfoxide (2 mL), respectively. The two transparent solutions were then mixed and allowed to stand at 25 °C for 12 hours to obtain yellow needle-like crystals, which is iHOF-37.

[0092] The prepared iHOF-37 is an ionic photochromic hydrogen-bonded organic framework, incorporating naphthalimide and viologen derivatives into its framework, exhibiting biradical synergistic properties. The iHOF-37 has a thermal stability temperature of 180℃; its proton conductivity at 100℃ and 98% relative humidity is 9.10 × 10⁻⁶. -3 S cm -1 The activation energy Ea is 0.44 eV.

[0093] Comparing Comparative Example 4 and Example 8, it can be seen that the iHOF-37 prepared in this comparative example has extremely low conductivity when not excited by light, and the upper limit of its overall conductivity is still lower than that of the example. This is because its inherent non-covalent interaction is weak, and it is highly dependent on external ultraviolet stimulation to generate free radicals to promote proton transition. It lacks the spontaneous and stable high-efficiency proton transport channel of the example.

[0094] Example 9

[0095] A method for preparing a POM-guanidine salt hydrogen-bonded material with ultra-high proton conductivity, comprising the following steps: (1) 4-guanidinobenzoate and phosphomolybdic acid hydrate (manufacturer: Shanghai Titan Technology Co., Ltd., brand: Adamas, CAS No.: 51429-74-4) were dissolved in deionized water at a molar ratio of 3:1 to obtain a mixed solution; wherein, the concentration of 4-guanidinobenzoate was 0.051 mol / L; (2) The mixed solution was placed in a hydrothermal reactor containing polytetrafluoroethylene and reacted for 5 days at a reaction temperature of 160°C. After the reaction was completed, the temperature was cooled to 45°C to obtain black-blue crystals. After washing and drying with ethanol three times, POM-guanidine salt hydrogen bond material with ultra-high proton conductivity was obtained.

[0096] The obtained POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity is self-assembled by multiple repeating units in three-dimensional space through a highly ordered hydrogen bond network. Each repeating unit belongs to the monoclinic crystal system with space group P21 / c. The unit cell parameters are: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, and V (unit cell volume) = 6898.6(16) Å. 3 ; The chemical formula for each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O 40 [C8N3O2H9]·7H2O contains three 4-guanidinobenzoic acid cations, one neutral 4-guanidinobenzoic acid molecule, one phosphomolybdate anion, and seven lattice water molecules. The 4-guanidinobenzoic acid ligand acts as a hydrogen bond donor, connecting not only to the terminal oxygen and bridging oxygen of phosphomolybdate through NH···O and CH···O bonds, but also to the lattice water molecules, thus forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds.

[0097] The POM-guanidinium hydrogen-bonded material exhibits ultra-high proton conductivity with a thermal stability temperature of 280℃; its proton conductivity at 90℃ and 98% relative humidity is 2.0 × 10⁻⁶. -2 S cm -1 The activation energy Ea is 0.3 eV.

[0098] The aforementioned POM-guanidinium salt hydrogen bond material with ultra-high proton conductivity has good proton conduction performance and can be used as a proton exchange membrane in proton exchange membrane fuel cells.

Claims

1. A POM-guanidinium hydrogen-bonded material with ultra-high proton conductivity, comprising multiple repeating units self-assembled in three-dimensional space via a hydrogen bond network, characterized in that: The chemical formula for each repeating unit is [C8N3O2H]. 10 ]3·[PMo 12 O 40 [C8N3O2H9]·7H2O contains 3 4-guanidinobenzoic acid cations, 1 neutral 4-guanidinobenzoic acid molecule, 1 phosphomolybdate anion, and 7 lattice water molecules; The thermal stability temperature of POM-guanidinium hydrogen-bonded materials with ultra-high proton conductivity is 220–280 °C; the proton conductivity at 90 °C and 98% relative humidity is 1.5 × 10⁻⁶. -2 ~2.0×10 -2 S cm -1 The activation energy Ea is 0.25~0.30 eV.

2. The POM-guanidinium hydrogen-bonded material with ultra-high proton conductivity according to claim 1, characterized in that, Each repeating unit belongs to the monoclinic crystal system, space group P21 / c, with the following cell parameters: a = 19.579(3) Å, b = 17.9220(19) Å, c = 21.669(3) Å, α = 90°, β = 114.861(5)°, γ = 90°, V = 6898.6(16) Å. 3 .

3. The POM-guanidinium hydrogen-bonded material with ultra-high proton conductivity according to claim 1, characterized in that, In each repeating unit, four 4-guanidinobenzoic acid ligands surround a phosphomolybdic acid. The 4-guanidinobenzoic acid ligands act as hydrogen bond donors, and through NH···O and CH···O bonds, they are connected not only to the terminal oxygen and bridging oxygen of phosphomolybdic acid, but also to lattice water molecules, thus forming multiple hydrogen bond interactions. Between adjacent repeating units, further cross-linking is achieved through hydrogen bonding, thereby extending indefinitely to form a three-dimensional supramolecular network. The hydrogen bonds formed between adjacent repeating units include two cases: one is that adjacent 4-guanidinobenzoic acid ligands are connected to each other through NH···O bonds and CH···O bonds, and the other is that 4-guanidinobenzoic acid ligands are connected to phosphomolybdic acid in adjacent repeating units through NH···O bonds and CH···O bonds.

4. A method for preparing a POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity as described in any one of claims 1 to 3, characterized in that: 4-guanidinobenzoate and phosphomolybdic acid hydrate were dissolved in deionized water at a molar ratio of 1:3 to 3:1, and then subjected to a hydrothermal reaction to obtain POM-guanidinohydrogen bond material with ultra-high proton conductivity.

5. The method for preparing a POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity according to claim 4, characterized in that, The hydrothermal reaction is carried out in a hydrothermal reactor containing polytetrafluoroethylene at a temperature of 140-160°C for 3-5 days.

6. The method for preparing a POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity according to claim 5, characterized in that, After the hydrothermal reaction is completed, the temperature is cooled to 25~45℃ to obtain blackish-blue crystals, which are then washed and dried repeatedly with ethanol.

7. The application of a POM-guanidinium salt hydrogen-bonded material with ultra-high proton conductivity as described in any one of claims 1 to 3, characterized in that: It is used as a proton exchange membrane in proton exchange membrane fuel cells.

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