Choline chloride / urea deep eutectic solvent modified ZIF-8 high-temperature proton exchange membrane as well as preparation method and application thereof

Abstract

The invention provides a choline chloride: urea deep eutectic solvent modified ZIF-8 high-temperature proton exchange membrane as well as a preparation method and application thereof, and belongs to the technical field of preparation of fuel cells and proton exchange membranes. The deep eutectic solvent and the zinc hydroxide nanowire membrane are compounded in situ through a suction filtration method, and then the deep eutectic solvent modified ZIF-8 high-temperature proton exchange membrane is prepared. In the ZIF-8 high-temperature proton exchange membrane, a zinc hydroxide nanowire membrane bears a choline chloride-urea deep eutectic solvent, so that the choline chloride-urea deep eutectic solvent is compounded into pores of ZIF-8 in situ, and the choline chloride-urea deep eutectic solvent is blocked in a ZIF-8 membrane to modify the inner wall; the preparation method is simple to operate, low in energy consumption and free of pollution, and the prepared ZIF-8 high-temperature proton exchange membrane can maintain stability, has extremely high proton conduction capacity and has very good practicability.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cell and proton exchange membrane preparation, and specifically relates to a choline chloride:urea deep eutectic solvent modified ZIF-8 high-temperature proton exchange membrane and a preparation method and application thereof. Background Art

[0002] Proton exchange membrane fuel cells can convert fuel chemical energy into electrical energy without combustion. Due to its high efficiency energy conversion and near zero emission, it is an ideal clean energy source. Proton exchange membrane fuel cells are mainly composed of gas diffusion layer, catalyst layer, proton exchange membrane, bipolar plate, etc. Proton exchange membrane fuel cells can be divided into two categories: low temperature and high temperature. Compared with low temperature proton exchange membrane fuel cells, high temperature proton exchange membrane fuel cells have higher carbon monoxide tolerance and simpler water heat management system, which makes them attract much attention in research and development.

[0003] At present, high-temperature proton exchange membranes are usually prepared by doping solid acids or organic acids in polymers, but this method has problems such as acid molecule loss, which makes it difficult to maintain long-term stability and high conductivity, limiting its practical application. Therefore, it is urgent to develop a high-temperature proton exchange membrane that can maintain long-term stability and improve proton conductivity, so as to promote the development and application of high-temperature proton exchange membrane fuel cells. Summary of the invention

[0004] In view of some deficiencies in the prior art, the present invention provides a ZIF-8 high temperature proton exchange membrane modified by a choline chloride:urea deep eutectic solvent, and a preparation method and application thereof; the present invention in situ composites the deep eutectic solvent with a zinc hydroxide nanowire membrane by a suction filtration method, thereby preparing the ZIF-8 high temperature proton exchange membrane modified by the deep eutectic solvent; in the ZIF-8 high temperature proton exchange membrane, the zinc hydroxide nanowire membrane carries the choline chloride:urea deep eutectic solvent, so that the choline chloride:urea deep eutectic solvent is in situ composited into the pores of the ZIF-8, thereby achieving the effect of blocking the choline chloride:urea deep eutectic solvent inside the ZIF-8 film and modifying the inner wall; the preparation method is simple to operate, low in energy consumption, and pollution-free, and the prepared ZIF-8 high temperature proton exchange membrane can have extremely high proton conductivity while maintaining stability, and has good practicality.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical means:

[0006] The present invention firstly provides a ZIF-8 high temperature proton exchange membrane modified by a choline chloride:urea deep eutectic solvent. The ZIF-8 high temperature proton exchange membrane is mainly composed of a dense ZIF-8 membrane, and the interior of the ZIF-8 membrane has nanopores. The choline chloride:urea deep eutectic solvent is uniformly loaded inside the nanopores of the ZIF-8 membrane to modify the interior of the ZIF-8 membrane. The proton donor group and the proton acceptor group in the choline chloride:urea deep eutectic solvent interact with each other to establish a continuous hydrogen bond network in the ZIF-8 nanopores.

[0007] The present invention also provides a method for preparing the above-mentioned choline chloride:urea deep eutectic solvent modified ZIF-8 high temperature proton exchange membrane, comprising:

[0008] (1) mixing choline chloride and urea and heating them to form a eutectic solvent to obtain a choline chloride:urea deep eutectic solvent;

[0009] The zinc hydroxide nanowires are vacuum filtered to obtain a zinc hydroxide nanowire film;

[0010] (2) introducing the choline chloride:urea deep eutectic solvent into the zinc hydroxide nanowire film in situ by vacuum filtration to obtain a zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite film;

[0011] (3) The zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite membrane was reacted in situ in the high temperature vapor of 2-methylimidazole to prepare the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane.

[0012] Preferably, in step (1), the molar ratio of choline chloride to urea is 1:2; and the heating temperature is 55-65°C.

[0013] Preferably, in step (1), the preparation method of the zinc hydroxide nanowires is: adding an ethanolamine solution to an equal volume of a zinc nitrate solution, stirring evenly, and standing at room temperature to obtain the zinc hydroxide nanowires.

[0014] Preferably, the solvent of the zinc nitrate solution and the ethanolamine solution is a mixture of water and ethanol, and the volume ratio of ethanol to water is 3:2;

[0015] The concentration of the ethanolamine solution is 1-2 mmol / L, and the concentration of the zinc nitrate solution is 3-5 mmol / L;

[0016] The room temperature standing time is 0.5 to 2 hours.

[0017] Preferably, in step (2), the preparation method of the zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite film comprises: placing the choline chloride:urea deep eutectic solvent on the surface of the zinc hydroxide nanowire film, vacuum filtering at 0.05-0.08 MPa until the choline chloride:urea deep eutectic solvent passes through the zinc hydroxide nanowire film, removing the residual choline chloride:urea deep eutectic solvent, and obtaining the zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite film.

[0018] Preferably, in step (3), the in-situ reaction conditions are: reacting in 2-methylimidazole high temperature steam at 100 to 140° C. for 18 to 30 hours.

[0019] Preferably, in the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane, the loading amount of the choline chloride:urea deep eutectic solvent is 11-13 wt %.

[0020] The present invention also provides the use of the above ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane in the preparation of high temperature fuel cells.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention is the first to in-situ composite the choline chloride:urea deep eutectic solvent on the zinc hydroxide nanowire membrane by vacuum filtration, and introduce it into the pores of the ZIF-8 film to achieve the blockade of the choline chloride:urea deep eutectic solvent, thereby changing the proton conductivity of the ZIF-8 film. Compared with other metal organic framework modification methods, this method avoids the complex organic synthesis steps of ligand modification, has the advantages of simplicity, high efficiency, low energy consumption and no pollution, and can maintain the stability of the guest molecule and extremely high proton conductivity under high temperature conditions.

[0023] The ZIF-8 / choline chloride of the present invention: urea deep eutectic solvent high temperature proton exchange membrane uses a dense ZIF-8 membrane as the main body of the high temperature proton exchange membrane, providing a nano-scale transmission channel; Choline chloride: urea deep eutectic solvent is uniformly loaded in the ZIF-8 nanopore, and the physicochemical environment of the ZIF-8 nanopore is modified, and the proton donor group and the proton acceptor group in the choline chloride: urea deep eutectic solvent interact with each other, and a continuous hydrogen bond network is established in the ZIF-8 nanopore, realizing rapid proton transmission. Because of the structural characteristics of choline chloride: urea deep eutectic solvent, protons are transmitted in the hydrogen bond network constructed by it with lower activation energy, which is conducive to achieving higher proton conductivity. In addition, the urea molecule in the choline chloride: urea deep eutectic solvent used in the present invention does not have a delocalized π bond, and compared with other raw materials with a delocalized π bond, it has a weaker electron donation ability and is more stable when forming a hydrogen bond network with choline chloride. The activation energy of proton transmission in this hydrogen bond network is lower, which is conducive to obtaining a higher proton conductivity.

[0024] Compared with the ZIF-8 / choline chloride: urea deep eutectic solvent composite material in the prior art, the ZIF-8 film prepared by the method of the present invention has a dense structure itself, and the dense structure can be obtained without adjusting the morphology by the choline chloride: urea deep eutectic solvent. The role of the choline chloride: urea deep eutectic solvent is to modify the ZIF-8 nanopores and build a continuous hydrogen bond network for proton transmission. Compared with the prior art, the choline chloride: urea deep eutectic solvent described in the present invention plays a role in proton transmission, and the prepared ZIF-8 / choline chloride: urea deep eutectic solvent high temperature proton exchange membrane has a high proton conductivity in a high temperature anhydrous environment, which can be applied to the field of fuel cells. In addition, the choline chloride:urea deep eutectic solvent is not easy to volatilize under high temperature environment, and its structure contains a large number of proton donor groups and proton acceptor groups. These characteristics enable it to form a continuous hydrogen bond network in the ZIF-8 nanopores as a proton transmission channel, and the hydrogen bond network can exist stably in a high temperature anhydrous environment, so that the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane obtains a higher proton conductivity in a high temperature anhydrous environment.

[0025] Compared with other in-situ composite methods, the present invention performs in-situ composite by vacuum filtration. When the vacuum filtration method is used for composite, the deep eutectic solvent can diffuse from the upper surface to the lower surface of the zinc hydroxide nanowire membrane under the driving force of air pressure. The air pressure driving force is greater than the capillary force, so that the deep eutectic solvent can be evenly loaded in the zinc hydroxide nanowire membrane, which is more beneficial to improve the high-temperature proton conductivity. The ZIF-8 / choline chloride: urea deep eutectic solvent high-temperature proton exchange membrane in the present invention is compared with the ZIF-8 composite film prepared by other methods, and the high-temperature proton conductivity is improved by 1 to 2 orders of magnitude. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a SEM image of the surface of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared in Example 1.

[0027] Figure 2 This is the XRD pattern of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared in Example 1.

[0028] Figure 3 This is the impedance diagram of the high temperature proton exchange membrane of ZIF-8 / choline chloride:urea deep eutectic solvent in Example 1.

[0029] Figure 4 This is a SEM image of the surface of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared in Example 2.

[0030] Figure 5 This is the XRD pattern of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared in Example 2.

[0031] Figure 6 This is a SEM image of the surface of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared in Example 3.

[0032] Figure 7 This is the XRD pattern of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared in Example 3.

[0033] Figure 8 This is the polarization curve of the H2 / O2 fuel cell assembled using the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane in Example 4.

[0034] Fig. 9 This is a SEM image of the surface of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared in Comparative Example 1.

[0035] Fig.10 This is the XRD pattern of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared in Comparative Example 1.

[0036] Fig.11 This is the impedance diagram of the high temperature proton exchange membrane of ZIF-8 / choline chloride:urea deep eutectic solvent in Comparative Example 1. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0038] Example 1: Preparation of high temperature proton exchange membrane using ZIF-8 / choline chloride:urea deep eutectic solvent

[0039] (1) Choline chloride and urea in a molar ratio of 1:2 are mixed and heated at 60° C. to form a colorless clear liquid, thereby obtaining a choline chloride:urea deep eutectic solvent.

[0040] Dissolve ethanolamine and zinc nitrate in a mixed solution of ethanol and water (V 乙醇 :V 水 =2:3), prepare an ethanolamine solution with a concentration of 1.6mmol / L and a zinc nitrate solution with a concentration of 2.4mmol / L for later use. Mix the ethanolamine solution and the zinc nitrate solution in a volume ratio of 1:1, and stir them thoroughly to obtain a mixed solution; seal the mixed solution and react at room temperature for 0.5h to obtain a zinc hydroxide nanowire solution, and vacuum filter the zinc hydroxide nanowires to obtain a zinc hydroxide nanowire film.

[0041] (2) The choline chloride:urea deep eutectic solvent was composited onto the zinc hydroxide nanowire film by a suction filtration method, wherein the volume of the choline chloride:urea deep eutectic solvent was 5 μL, thereby obtaining a zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite film.

[0042] (3) The zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite membrane is reacted in situ in 2-methylimidazole high temperature steam at 120°C for 24 hours. After the reaction, a ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is obtained. The mass fraction of the choline chloride:urea deep eutectic solvent in the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is 11.5 wt%.

[0043] Figure 1 The SEM photograph of the surface of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane shows that the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is a polycrystalline film with good grain shape growth, which conforms to the morphological characteristics of ZIF-8 grains, with a grain size between 200nm and 1μm, densely intergrown grains, no obvious cracks in the film, and continuous and dense. .

[0044] Figure 2 This is the XRD diagram of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane. It can be seen from the figure that the peak structure of the modified ZIF-8 is well maintained. This proves the successful synthesis of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane.

[0045] The electrochemical impedance spectroscopy (EIS) test was performed on the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared above. During the EIS test, the AC frequency range was 1 Hz to 1 MHz. The test results are shown in FIG. Figure 3 As shown. Figure 3 It can be seen that the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane of the present invention has a strong proton conductivity. At 160°C, the conductivity reaches 1.12×10 -2 S cm -1 .

[0046] Example 2: Preparation of high temperature proton exchange membrane using ZIF-8 / choline chloride:urea deep eutectic solvent

[0047] (1) Choline chloride and urea in a molar ratio of 1:2 are mixed and heated at 60° C. to form a colorless clear liquid, thereby obtaining a choline chloride:urea deep eutectic solvent.

[0048] Dissolve ethanolamine and zinc nitrate in a mixed solution of ethanol and water (V 乙醇 :V 水 =2:3), prepare an ethanolamine solution with a concentration of 2mmol / L and a zinc nitrate solution with a concentration of 5mmol / L for later use. Mix the ethanolamine solution and the zinc nitrate solution in a volume ratio of 1:1, and stir them thoroughly to obtain a mixed solution; seal the mixed solution and react at room temperature for 1h to obtain a zinc hydroxide nanowire solution, and vacuum filter the zinc hydroxide nanowires to obtain a zinc hydroxide nanowire film.

[0049] (2) The choline chloride:urea deep eutectic solvent was composited onto the zinc hydroxide nanowire film by a suction filtration method, wherein the volume of the choline chloride:urea deep eutectic solvent was 3 μL, thereby obtaining a zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite film.

[0050] (3) The zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite membrane is reacted in situ in 2-methylimidazole high temperature steam at 140°C for 18 hours. After the reaction, a ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is obtained. The mass fraction of the choline chloride:urea deep eutectic solvent in the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is 10 wt%.

[0051] Figure 4 This is a SEM photograph of the surface of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane. It can be seen from the figure that the ZIF-8 high temperature proton exchange membrane modified by the choline chloride:urea deep eutectic solvent has good grain intergrowth and the film is continuous without cracks.

[0052] Figure 5This is the XRD diagram of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane. It can be seen from the figure that the peak structure of the modified ZIF-8 is well maintained. This proves the successful synthesis of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane.

[0053] Example 3: Preparation of high temperature proton exchange membrane using ZIF-8 / choline chloride:urea deep eutectic solvent

[0054] (1) Choline chloride and urea in a molar ratio of 1:2 are mixed and heated at 70° C. to form a colorless clear liquid, thereby obtaining a choline chloride:urea deep eutectic solvent.

[0055] Dissolve ethanolamine and zinc nitrate in a mixed solution of ethanol and water (V 乙醇 :V 水 =2:3), prepare an ethanolamine solution with a concentration of 1mmol / L and a zinc nitrate solution with a concentration of 3mmol / L for later use. Mix the ethanolamine solution and the zinc nitrate solution in a volume ratio of 1:1, and stir them thoroughly to obtain a mixed solution; seal the mixed solution and react at room temperature for 1h to obtain a zinc hydroxide nanowire solution, and vacuum filter the zinc hydroxide nanowires to obtain a zinc hydroxide nanowire film.

[0056] (2) The choline chloride:urea deep eutectic solvent was composited onto the zinc hydroxide nanowire film by a suction filtration method, wherein the volume of the choline chloride:urea deep eutectic solvent was 10 μL, thereby obtaining a zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite film.

[0057] (3) The zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite membrane is reacted in situ in 2-methylimidazole high temperature steam at 130°C for 30 hours. After the reaction, a ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is obtained. The mass fraction of the choline chloride:urea deep eutectic solvent in the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is 11.9wt%.

[0058] Figure 6 This is a SEM photograph of the surface of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane. It can be seen from the figure that the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is a polycrystalline film with good grain shape growth, which conforms to the morphological characteristics of ZIF-8 grains. The grain size is between 200nm and 1μm, the grains are densely intergrown, there are no obvious cracks in the film, and it is continuous and dense.

[0059] Figure 7This is the XRD diagram of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane. It can be seen from the figure that the peak structure of the modified ZIF-8 is well maintained. This proves the successful synthesis of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane.

[0060] Embodiment 4:

[0061] In order to verify the applicability of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane in fuel cells, it was loaded into a warm proton exchange membrane fuel cell for testing. The steps are as follows: a platinum carbon catalyst was coated on both sides of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared in Example 1. The amount of platinum carbon catalyst was 0.5 mg cm -2 , placed between two pieces of carbon cloth, and hot pressed at 125℃ and 6.4Mpa pressure to prepare fuel cell membrane electrode. Under anhydrous conditions at 150℃, H2 and O2 were introduced into both sides of the fuel cell membrane electrode, and its polarization curve was tested and the output power density was calculated, such as Figure 8 shown.

[0062] from Figure 8 It can be seen that the fuel cell equipped with ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane has an output power density of 35.2 mW / cm 2 , proving that the ZIF-8 / choline chloride:urea deep eutectic solvent high-temperature proton exchange membrane not only has good high-temperature proton conductivity, but also has good practical application potential.

[0063] Comparative Example 1:

[0064] (1) Choline chloride and urea in a molar ratio of 1:2 are mixed and heated at 60° C. to form a colorless clear liquid, thereby obtaining a choline chloride:urea deep eutectic solvent.

[0065] Dissolve ethanolamine and zinc nitrate in a mixed solution of ethanol and water (V 乙醇 :V 水 =2:3), prepare an ethanolamine solution with a concentration of 1.6mmol / L and a zinc nitrate solution with a concentration of 2.4mmol / L for later use. Mix the ethanolamine solution and the zinc nitrate solution in a volume ratio of 1:1, and stir them thoroughly to obtain a mixed solution; seal the mixed solution and react at room temperature for 0.5h to obtain a zinc hydroxide nanowire solution, and vacuum filter the zinc hydroxide nanowires to obtain a zinc hydroxide nanowire film.

[0066] (2) The choline chloride:urea deep eutectic solvent was composited onto the zinc hydroxide nanowire film by spin coating, wherein the volume of the choline chloride:urea deep eutectic solvent was 5 μL, which was dropped onto the upper surface of the zinc hydroxide nanowire film, first rotated at a low speed of 150 rpm for 10 seconds, and then rotated at a high speed of 3000 rpm for 30 seconds to obtain a zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite film.

[0067] (3) The zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite membrane is reacted in situ in 2-methylimidazole high temperature steam at 120°C for 24 hours. After the reaction, a ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is obtained. The mass fraction of the choline chloride:urea deep eutectic solvent in the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is 11.5 wt%.

[0068] Fig. 9 This is a SEM photograph of the surface of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane. It can be seen from the figure that the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane is a polycrystalline film with good grain shape growth, which conforms to the morphological characteristics of ZIF-8 grains. The grain size is between 200nm and 1μm, the grains are densely intergrown, there are no obvious cracks in the film, and it is continuous and dense.

[0069] Fig.10 This is the XRD diagram of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane. It can be seen from the figure that the peak structure of the modified ZIF-8 is well maintained. This proves the successful synthesis of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane.

[0070] The electrochemical impedance spectroscopy (EIS) test was performed on the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared above. During the EIS test, the AC frequency range was 1 Hz to 1 MHz. The test results are shown in FIG. Fig.11 As shown. Fig.11 It can be seen that the proton conductivity of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared by the spin coating method is lower than that of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared in Example 1. At 160°C, the conductivity is only 2.76×10 -3 S cm -1 Therefore, the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane prepared by the vacuum filtration method of the present invention has higher proton conductivity and can be applied to the field of fuel cells.

[0071] In summary, the present invention in situ composites the deep eutectic solvent with the zinc hydroxide nanowire membrane by a suction filtration method, thereby preparing a deep eutectic solvent-modified ZIF-8 high temperature proton exchange membrane; in the ZIF-8 high temperature proton exchange membrane, the zinc hydroxide nanowire membrane carries the choline chloride: urea deep eutectic solvent, so that the choline chloride: urea deep eutectic solvent is in situ composited into the pores of ZIF-8, thereby achieving the effect of blocking the choline chloride: urea deep eutectic solvent inside the ZIF-8 film and modifying the inner wall; the preparation method is simple to operate, low in energy consumption, and pollution-free, and the prepared ZIF-8 high temperature proton exchange membrane can have extremely high proton conductivity while maintaining stability, and has a good application in high temperature fuel cells.

[0072] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A choline chloride:urea deep eutectic solvent modified ZIF-8 high temperature proton exchange membrane, It is characterized in that The ZIF-8 high temperature proton exchange membrane is mainly composed of a dense ZIF-8 membrane, and the ZIF-8 membrane has nanopores inside; the choline chloride:urea deep eutectic solvent is uniformly loaded inside the nanopores of the ZIF-8 membrane to modify the inside of the ZIF-8 membrane; the proton donor group and the proton acceptor group in the choline chloride:urea deep eutectic solvent interact with each other to establish a continuous hydrogen bond network in the ZIF-8 nanopores.

2. The choline chloride:urea deep eutectic solvent modified ZIF-8 high temperature proton exchange membrane according to claim 1, It is characterized in that In the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane, the loading amount of the choline chloride:urea deep eutectic solvent is 11-13 wt %.

3. The method for preparing the choline chloride:urea deep eutectic solvent-modified ZIF-8 high temperature proton exchange membrane according to claim 1, It is characterized in that include: (1) mixing choline chloride and urea and heating them to form a eutectic solvent to obtain a choline chloride:urea deep eutectic solvent; The zinc hydroxide nanowires are vacuum filtered to obtain a zinc hydroxide nanowire film; (2) introducing the choline chloride:urea deep eutectic solvent into the zinc hydroxide nanowire film in situ by vacuum filtration to obtain a zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite film; (3) The zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite membrane was reacted in situ in the high temperature vapor of 2-methylimidazole to prepare the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane.

4. The method for preparing a choline chloride:urea deep eutectic solvent-modified ZIF-8 high temperature proton exchange membrane according to claim 3, It is characterized in that In step (1), the molar ratio of choline chloride to urea is 1:2; and the heating temperature is 55-65°C.

5. The method for preparing a choline chloride:urea deep eutectic solvent-modified ZIF-8 high temperature proton exchange membrane according to claim 3, It is characterized in that In step (1), the preparation method of the zinc hydroxide nanowires is: adding an ethanolamine solution to an equal volume of a zinc nitrate solution, stirring evenly, and standing at room temperature to obtain the zinc hydroxide nanowires.

6. The method for preparing a choline chloride:urea deep eutectic solvent-modified ZIF-8 high temperature proton exchange membrane according to claim 5, It is characterized in that The solvent of the zinc nitrate solution and the ethanolamine solution is a mixture of water and ethanol, and the volume ratio of ethanol to water is 3:2; The concentration of the ethanolamine solution is 1-2 mmol / L, and the concentration of the zinc nitrate solution is 3-5 mmol / L; The room temperature standing time is 0.5 to 2 hours.

7. The method for preparing a choline chloride:urea deep eutectic solvent-modified ZIF-8 high temperature proton exchange membrane according to claim 3, It is characterized in that In step (2), the preparation method of the zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite film includes: placing the choline chloride:urea deep eutectic solvent on the surface of the zinc hydroxide nanowire film, vacuum filtering at 0.05-0.08 MPa until the choline chloride:urea deep eutectic solvent passes through the zinc hydroxide nanowire film, removing the residual choline chloride:urea deep eutectic solvent, and obtaining the zinc hydroxide nanowire / choline chloride:urea deep eutectic solvent composite film.

8. The method for preparing a choline chloride:urea deep eutectic solvent-modified ZIF-8 high temperature proton exchange membrane according to claim 3, It is characterized in that In step (3), the in-situ reaction conditions are: reacting in 2-methylimidazole high temperature steam at 100-140° C. for 18-30 hours.

9. The method for preparing a choline chloride:urea deep eutectic solvent-modified ZIF-8 high temperature proton exchange membrane according to claim 3, It is characterized in that In the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane, the loading amount of the choline chloride:urea deep eutectic solvent is 11-13 wt %.

10. Use of the ZIF-8 / choline chloride:urea deep eutectic solvent high temperature proton exchange membrane according to claim 1 in the preparation of a high temperature fuel cell.

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