A method for preparing a composite proton exchange membrane and its application

Abstract

This invention relates to the field of proton exchange membrane electrolysis technology, and more particularly to a method for preparing a composite proton exchange membrane and its application. The method utilizes pH and ion gradients to facilitate the migration of noble metal ions within the membrane. Noble metal ions are doped into the anode side of the membrane, and a longitudinal impregnation method is used to achieve a uniform distribution of noble metal particles within the membrane. Subsequently, the reduction time via in-situ sodium borohydride is controlled, as is the amount of hydrogen removal catalyst doped, to prepare an ultra-low noble metal loading composite membrane. This invention prepares a composite proton exchange membrane through noble metal impregnation reduction, reducing hydrogen permeation at the membrane electrode while maintaining performance, lowering the hydrogen content in the oxygen on the anode side, improving product purity, and enhancing safety. The uniform distribution of the noble metal significantly improves catalyst utilization, allowing the catalyst-coated membrane to achieve excellent hydrogen removal effects with a small amount of noble metal impregnation.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane electrolysis technology, and more particularly to a method for preparing a composite proton exchange membrane and its application. Background Technology

[0002] Hydrogen is considered to play a vital role in decarbonization and sustainable energy systems, serving as an alternative energy carrier or fuel for future renewable energy production. Producing and using hydrogen via electrochemical cells is the most promising approach to achieving its widespread commercialization. Water electrolysis is an electrochemical reaction that splits water into hydrogen and oxygen. Proton exchange membrane (PEM) water electrolysis has been extensively studied due to its advantages, including using pure water as a reactant, compact structure, high operating current density, high gas production, high hydrogen purity, fast response, and tolerance to high operating pressures. It has been applied in various fields, including fuel cell hydrogen supply, industrial feedstocks, and medical treatment, through coupling with green electricity.

[0003] Compared to traditional atmospheric pressure PEM water electrolysis, high-pressure PEM water electrolyzers can supply hydrogen to end users under high pressure, requiring minimal energy for further hydrogen compression and storage. This reduces costs while increasing maximum voltage efficiency, making high-pressure PEM water electrolysis a current research hotspot. However, due to the water absorption characteristics of the membrane, gas permeation remains a problem during the operation of high-pressure PEM water electrolyzers. In the low current density region, gas permeation is closely related to safety and efficiency, while in the high current density region, permeation affects membrane degradation. Therefore, the fabrication of membrane electrodes with low hydrogen permeation and high performance is crucial for the safe and efficient operation of water electrolyzers.

[0004] To address the aforementioned issues, patent CN104726891A discloses a proton exchange membrane water electrolyzer with internal hydrogen removal function and its fabrication method. By modifying the current collector and bipolar plate surfaces after the membrane electrode with a hydrogen removal catalyst, hydrogen and oxygen can react electrochemically on the catalyst surface to generate water, thus achieving hydrogen removal within the water electrolyzer stack. However, this method requires a high catalyst loading, and removing hydrogen outside the membrane electrode may be difficult to achieve under high pressure. Patent CN116926618A discloses a method for preparing a catalyst-coated proton exchange membrane with a composite catalyst layer structure. This method utilizes a functional layer of hydrogen removal noble metal catalyst added between the anode catalyst layer and the proton exchange membrane to reduce hydrogen permeation during water electrolysis. However, adding the functional layer increases the thickness of the membrane electrode and makes it difficult to achieve a uniform distribution of low-load noble metal. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a composite proton exchange membrane and its application. This invention involves doping noble metal ions into the anode side of the membrane through noble metal impregnation reduction. This reduces hydrogen permeation of the membrane electrode and decreases the hydrogen content in the oxygen on the anode side while maintaining performance, thereby improving product purity and safety. This composite proton exchange membrane also exhibits good proton conductivity and requires no phosphoric acid during preparation.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] This invention provides a method for preparing a composite proton exchange membrane, the method comprising the following steps:

[0008] (1) Dissolve the compound containing noble metal ions in water, stir thoroughly to dissolve, and adjust the pH to 7~13 to obtain solution S1;

[0009] (2) Dissolve K2SO4 in water, stir thoroughly to dissolve, and adjust the pH to 1~3 to obtain solution S2;

[0010] (3) After acid washing, the proton exchange membrane M1 is washed with water to obtain the activated membrane M2;

[0011] (4) Add solutions S1 and S2 to both sides of the activated membrane M2 and impregnate longitudinally to obtain membrane M3; the longitudinal direction refers to the membrane being parallel to the bottom of the impregnation container, with solutions S1 and S2 located on the upper and lower sides of the membrane respectively;

[0012] (5) Dissolve NaBH4 in water, stir thoroughly to dissolve, and adjust the pH to 7-13 to obtain solution S3;

[0013] (6) Add solution S3 to the upper side of membrane M3 for reduction treatment to obtain membrane M4;

[0014] (7) The membrane M4 is acid-washed and water-washed to obtain the composite proton exchange membrane.

[0015] In the preparation method of this invention, the raw materials for the composite proton exchange membrane include a catalyst and a proton exchange membrane, wherein: the catalyst is a catalyst that can catalyze the hydrogenation reaction to produce water, including noble metal catalysts such as Pt, Pd and their complexes; the proton exchange membrane is a proton exchange membrane that can exchange ions with noble metals, including perfluorosulfonic acid membranes and perfluorosulfonic acid-based composite membranes.

[0016] Based on the above technical solution, preferably, in step (1), the molar concentration of the compound containing noble metal ions in solution S1 is 0.4~4 mM; and KOH is used to adjust the pH.

[0017] In step (2), the molar concentration of K2SO4 in solution S2 is 0.01~0.1 M; H2SO4 is used to adjust the pH.

[0018] In step (3), the acid used for pickling is 0.5 M H2SO4;

[0019] In step (5), the molar concentration of NaBH4 in solution S3 is 0.2 ~ 1 M; the pH is adjusted using KOH;

[0020] In step (7), the acid used for pickling is HClO4 or H2SO4, with a molar concentration of 1~5 M.

[0021] Based on the above technical solutions, preferably, in step (1), the compound containing noble metal ions is one or more of Pt(NH3)4(NO3)2, Pt(NH3)4Cl2, Pd(NH3)4(NO3)2, and Pd(NH3)4Cl2;

[0022] Based on the above technical solutions, the preferred one is...

[0023] When the compound containing noble metal ions is a Pt compound, the pH in steps (1) and (5) is independently 10 to 13; when the compound containing noble metal ions is a Pd compound, the pH in steps (1) and (5) is independently 7 to 11; when the compound containing noble metal ions is a combination of Pt and Pd compounds, the pH in steps (1) and (5) is independently 10 to 11.

[0024] Based on the above technical solutions, preferably, in step (3), the temperature of pickling and water washing is 80 ℃, the pickling time is 30~60 min, and the water washing time is 30~60 min;

[0025] In step (4), the immersion temperature is 30~40 ℃ and the immersion time is 1~24 h;

[0026] In step (6), the reduction temperature is 30~40 ℃ and the reduction time is 30~90 min;

[0027] In step (7), the pickling temperature is 20 ℃, the pickling time is 12~48 h, the water washing temperature is 80 ℃, and the water washing time is 30~60 min.

[0028] Another aspect of the present invention provides a composite proton exchange membrane prepared by the above method.

[0029] The present invention also provides a membrane electrode comprising a composite proton exchange membrane, and an anode catalyst layer located on one side of the noble metal impregnation and a cathode catalyst layer located on the opposite side, wherein the composite proton exchange membrane is the composite proton exchange membrane described above.

[0030] Based on the above technical solutions, preferably, the anode catalyst layer includes an anode catalyst and ionomer 1, the anode catalyst includes one or more of Ir-based catalysts, Ru-based catalysts and IrRu composite catalysts, and the ionomer 1 is a perfluorosulfonic acid resin;

[0031] The cathode catalyst layer includes a cathode catalyst and ionomer 2. The cathode catalyst includes one or more of Pt-based catalysts and Pd-based catalysts, and the ionomer 2 is a perfluorosulfonic acid resin.

[0032] Based on the above technical solutions, preferably, the anode catalyst includes Ir, IrOx, Ru, RuOx, IrRuOx, IrY alloy, RuY alloy, IrRuY alloy and corresponding supported catalysts, wherein Y is selected from one or more of Pt, Pd, Au, Ag, Fe, Co, Ni, Cu and Mn;

[0033] The carrier includes one or more of carbon, titanium dioxide, and tungsten oxide.

[0034] Based on the above technical solutions, preferably, the Pt-based catalyst includes one or more of Pt / C, Pt, and PtM alloys, and the Pd-based catalyst includes one or more of Pd / C, Pd, and PdM alloys, wherein M is selected from one or more of Ir, Ru, Au, Co, Fe, Cu, and Ni.

[0035] Based on the above technical solutions, preferably, the preparation method of the anode catalyst layer and the cathode catalyst layer is as follows: the anode catalyst and the cathode catalyst are independently mixed with perfluorosulfonic acid resin and solvent to obtain corresponding catalyst slurries, and then the anode catalyst layer and the cathode catalyst layer are prepared on the surface of the proton exchange membrane by spraying, coating or transfer method; the solvent includes one or more of water, methanol, ethanol, ethylene glycol, n-propanol and isopropanol.

[0036] The present invention also provides an application of the above-mentioned catalytic membrane electrode in a water electrolysis cell.

[0037] The beneficial effects of this invention are as follows:

[0038] (1) This invention prepares a composite proton exchange membrane by noble metal impregnation reduction. The migration of noble metal ions within the membrane is achieved using pH and ion gradients. Noble metal ions are doped into the anode side of the membrane, and uniform distribution of noble metal particles within the membrane is achieved through longitudinal impregnation. Subsequently, the reduction time via in-situ sodium borohydride is controlled, as is the doping amount of the hydrogen removal catalyst, to prepare an ultra-low noble metal loading composite membrane. Using this method, the doping of noble metals causes minimal structural damage to the membrane, solving the structural damage problem caused by traditional doping methods.

[0039] (2) In the preparation method of the present invention, the longitudinal impregnation solves the problem that in the existing process, due to gravity, most of the precious metals are deposited in the lower half to form a gradient, which makes it impossible to reduce the loading and uniformly eliminate hydrogen. The lower liquid is removed during the reduction process to solve the problem that the reduction is point-like due to gas diffusion, thereby obtaining a composite film with uniform impregnation of precious metals and realizing the uniform hydrogen elimination function inside the electrode. By adjusting the pH, the ultra-low loading impregnation of the difficult-to-impregnate Pd is achieved, and the same hydrogen elimination effect as impregnated Pt is achieved while ensuring the electrode performance.

[0040] (3) In the preparation method of the present invention, the hydrogen permeated by the noble metal in the membrane is oxidized to water, which reduces the amount of hydrogen permeation in the membrane electrode while ensuring performance, reduces the hydrogen content in the oxygen on the anode side, improves the purity of the product and enhances safety. The uniform distribution of the noble metal fully improves the utilization rate of the catalyst, so that the catalyst coating membrane can obtain excellent hydrogen removal effect with a small amount of noble metal impregnation. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the clamp structure for fixing the membrane used in this invention;

[0042] Figure 2 A schematic diagram of the fixture structure for using a fixed membrane in Comparative Example 2;

[0043] Figure 3 The diagram shows the composite membranes prepared in Example 1, Comparative Example 2, and Comparative Example 4. a represents Example 1, b represents Comparative Example 2, and c represents Comparative Example 4.

[0044] Figure 4 The graph shows the change of hydrogen content in oxygen on the anode side of the water electrolyzer for the composite membranes prepared in Comparative Example 1, Example 1, and Example 2 as a function of current density. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0046] Unless otherwise specified, the materials used in the embodiments of the present invention can be obtained commercially or prepared according to conventional methods known to those skilled in the art.

[0047] Example 1

[0048] (1) Dissolve Pt(NH3)4(NO3)2 in water and stir thoroughly to obtain a 0.4 mM Pt(NH3)4(NO3)2 solution. Add KOH to adjust the pH to 13.

[0049] (2) Dissolve K2SO4 in water and stir thoroughly to obtain a 0.013 M K2SO4 solution. Add H2SO4 to adjust the pH to 1.

[0050] (3) The Nafion 212 membrane was treated in 0.5 M H2SO4 at 80 °C for 30 min, and then treated in ultrapure water at 80 °C for 30 min. The membrane was washed with water until pH=7 to obtain the treated membrane.

[0051] (4) According to Figure 1 The membrane was fixed by placing the platinum-containing solution obtained in step (1) on the upper layer and the potassium sulfate solution obtained in step (2) on the lower layer. The membrane treated in step (3) was longitudinally immersed in the solution and immersed at 30 °C for 1 h.

[0052] (5) Dissolve NaBH4 in water and stir thoroughly to obtain a 0.2 M NaBH4 solution. Add KOH to adjust the pH to 11.

[0053] (6) Pour out the solutions on both sides, replace the upper solution with 0.2 M NaBH4 (pH=11, KOH) obtained in step (5), and reduce at 30 ℃ for 60 min;

[0054] (7) Take out the membrane obtained in step (6), wash it three times with ultrapure water, treat it with 5 M HClO4 at room temperature for 48 h, treat it with ultrapure water at 80 ℃ for 30 min, and then wash it with ultrapure water to obtain the composite membrane.

[0055] An Ir loading of 1 mg cm⁻¹ was sprayed onto the Pt-impregnated side of the composite membrane. -2 The catalyst layer is coated on one side, and on the other side, a Pt loading of 0.4 mg / cm³ is sprayed on the other side. -2 The catalyst layer was used to prepare the membrane electrode.

[0056] Example 2

[0057] (1) Dissolve Pd(NH3)4(NO3)2 in water and stir thoroughly to obtain a 0.4 mM Pd(NH3)4(NO3)2 solution (pH=7).

[0058] (2) Dissolve K2SO4 in water and stir thoroughly to obtain a 0.013 M K2SO4 solution. Add H2SO4 to adjust the pH to 1.

[0059] (3) The Nafion 212 membrane was treated in 0.5 M H2SO4 at 80 °C for 30 min, and then treated in ultrapure water at 80 °C for 30 min. The membrane was washed with water until pH=7 to obtain the treated membrane.

[0060] (4) According to Figure 1 The membrane was fixed by placing the palladium-containing solution obtained in step (1) on the upper layer and the potassium sulfate solution obtained in step (2) on the lower layer. The membrane treated in step (3) was longitudinally immersed in the solution and immersed at 30 °C for 1 h.

[0061] (5) Dissolve NaBH4 in water and stir thoroughly to obtain a 0.2 M NaBH4 solution (pH=7).

[0062] (6) Pour out the solutions on both sides, replace the upper solution with 0.2 M NaBH4 obtained in step (6), and reduce at 30 °C for 60 min;

[0063] (7) Take out the membrane obtained in step (6), wash it three times with ultrapure water, treat it with 1 M H2SO4 at room temperature for 48 h, treat it with ultrapure water at 80 ℃ for 30 min, and then wash it with ultrapure water to obtain the composite membrane.

[0064] An Ir loading of 1 mg cm⁻¹ was sprayed onto the Pd-impregnated side of the composite membrane. -2 The catalyst layer is coated on one side, and on the other side, a Pt loading of 0.4 mg / cm³ is sprayed on the other side. -2 The catalyst layer was used to prepare the membrane electrode.

[0065] Example 3

[0066] (1) Dissolve Pt(NH3)4Cl2 in water and stir thoroughly to obtain a 0.4 mM Pt(NH3)4Cl2 solution. Add KOH to adjust the pH to 13.

[0067] (2) Dissolve K2SO4 in water and stir thoroughly to obtain a 0.013 M K2SO4 solution. Add H2SO4 to adjust the pH to 1.

[0068] (3) The Nafion 212 membrane was treated in 0.5 M H2SO4 at 80 °C for 30 min, and then treated in ultrapure water at 80 °C for 30 min. The membrane was washed with water until pH=7 to obtain the treated membrane.

[0069] (4) According to Figure 1 The membrane was fixed in a manner in which the platinum-containing solution obtained in step (2) was placed on the upper layer and the potassium sulfate solution obtained in step (2) was placed on the lower layer. The membrane treated in step (3) was longitudinally immersed in the solution and immersed at 30 °C for 1 h.

[0070] (5) Dissolve NaBH4 in water and stir thoroughly to obtain a 0.2 M NaBH4 solution. Add KOH to adjust the pH to 11.

[0071] (6) Pour out the solutions on both sides, replace the upper solution with 0.2 M NaBH4 (pH=11, KOH) obtained in step (5), and reduce at 30 ℃ for 60 min;

[0072] (7) Take out the membrane obtained in step (6), wash it three times with ultrapure water, treat it with 5 M HClO4 at room temperature for 48 h, treat it with ultrapure water at 80 ℃ for 30 min, and then wash it with ultrapure water to obtain the composite membrane.

[0073] An Ir loading of 1 mg cm⁻¹ was coated onto the Pt-impregnated side of the composite membrane. -2 The catalyst layer is coated on one side, and on the other side, a Pt loading of 0.4 mg / cm³ is applied. -2 The catalyst layer was used to prepare the membrane electrode.

[0074] Example 4

[0075] (1) Dissolve Pt(NH3)4(NO3)2 in water and stir thoroughly to obtain a 0.4 mM Pt(NH3)4(NO3)2 solution. Add KOH to adjust the pH to 13.

[0076] (2) Dissolve K2SO4 in water and stir thoroughly to obtain a 0.013 M K2SO4 solution. Add H2SO4 to adjust the pH to 1.

[0077] (3) The Nafion 115 membrane was treated in 0.5 M H2SO4 at 80 °C for 30 min, and then treated in ultrapure water at 80 °C for 30 min. The membrane was washed with water until pH=7 to obtain the treated membrane.

[0078] (4) According to Figure 1 The membrane was fixed by placing the platinum-containing solution obtained in step (1) on the upper layer and the potassium sulfate solution obtained in step (2) on the lower layer. The membrane treated in step (3) was longitudinally immersed in the solution and immersed at 30 °C for 1 h.

[0079] (5) Dissolve NaBH4 in water and stir thoroughly to obtain a 0.2 M NaBH4 solution. Add KOH to adjust the pH to 11.

[0080] (6) Pour out the solutions on both sides, replace the upper solution with 0.2 M NaBH4 (pH=11, KOH) obtained in step (5), and reduce at 30 ℃ for 30 min;

[0081] (7) Take out the membrane obtained in step (6), wash it three times with ultrapure water, treat it with 5 M HClO4 at room temperature for 48 h, treat it with ultrapure water at 80 ℃ for 30 min, and then wash it with ultrapure water to obtain the composite membrane.

[0082] An Ir loading of 1 mg cm⁻¹ was sprayed onto the Pt-impregnated side of the composite membrane. -2 The catalyst layer is coated on one side, and on the other side, a Pt loading of 0.4 mg / cm³ is sprayed on the other side. -2 A catalyst coating film with hydrogen removal function was prepared by adding a catalyst layer.

[0083] Comparative Example 1

[0084] Take a Nafion 212 membrane, treat it in 0.5 M H2SO4 at 80 ℃ for 30 min, then treat it in ultrapure water at 80 ℃ for 30 min, and wash it with water until pH=7 to obtain the treated membrane.

[0085] Ir loading of 1 mg cm⁻¹ was sprayed onto one side of the membrane. -2 The catalyst layer is coated on one side, and on the other side, a Pt loading of 0.4 mg / cm³ is sprayed on the other side. -2 The catalyst layer was used to prepare the membrane electrode.

[0086] Comparative Example 2

[0087] (1) Dissolve Pt(NH3)4(NO3)2 in water and stir thoroughly to obtain a 0.4 mM Pt(NH3)4(NO3)2 solution. Add KOH to adjust the pH to 13.

[0088] (2) Dissolve K2SO4 in water and stir thoroughly to obtain a 0.013 M K2SO4 solution. Add H2SO4 to adjust the pH to 1.

[0089] (3) The Nafion 212 membrane was treated in 0.5 M H2SO4 at 80 °C for 30 min, and then treated in ultrapure water at 80 °C for 30 min. The membrane was washed with water until pH=7 to obtain the treated membrane.

[0090] (4) According to Figure 2 The membrane was fixed in a way that the platinum-containing solution obtained in step (1) was placed on the right side and the potassium sulfate solution obtained in step (2) was placed on the left side. The membrane treated in step (3) was immersed in the solution and immersed at 30 °C for 24 h.

[0091] (5) Dissolve NaBH4 in water and stir thoroughly to obtain a 0.2 M NaBH4 solution. Add KOH to adjust the pH to 11.

[0092] (6) Pour out the solutions on both sides, replace the upper solution with 0.2 M NaBH4 (pH=11, KOH) obtained in step (5), and reduce at 30 ℃ for 60 min;

[0093] (7) Take out the membrane obtained in step (6), wash it three times with ultrapure water, treat it with 5 M HClO4 at room temperature for 48 h, treat it with ultrapure water at 80 ℃ for 30 min, and then wash it with ultrapure water to obtain the composite membrane.

[0094] An Ir loading of 1 mg cm⁻¹ was coated onto the Pt-impregnated side of the composite membrane. -2 The catalyst layer is coated on one side, and on the other side, a Pt loading of 0.4 mg / cm³ is applied. -2 The catalyst layer was used to prepare the membrane electrode.

[0095] Comparative Example 3

[0096] (1) Dissolve Pt(NH3)4(NO3)2 in water and stir thoroughly to obtain a 0.4 mM Pt(NH3)4(NO3)2 solution. Add KOH to adjust the pH to 13.

[0097] (2) Dissolve K2SO4 in water and stir thoroughly to obtain a 0.013 M K2SO4 solution. Add H2SO4 to adjust the pH to 1.

[0098] (3) The Nafion 212 membrane was treated in 0.5 M H2SO4 at 80 °C for 30 min, and then treated in ultrapure water at 80 °C for 30 min. The membrane was washed with water until pH=7 to obtain the treated membrane.

[0099] (4) According to Figure 1 The membrane was fixed in a manner in which the platinum-containing solution obtained in step (1) was placed on the upper layer and the potassium sulfate solution obtained in step (2) was placed on the lower layer. The membrane treated in step (4) was longitudinally immersed in the solution and immersed at 30 °C for 1 h.

[0100] (5) Dissolve NaBH4 in water and stir thoroughly to obtain a 0.2 M NaBH4 solution. Add KOH to adjust the pH to 11.

[0101] (6) Pour out the solutions on both sides, replace the upper solution with 0.2 M NaBH4 (pH=11, KOH) obtained in step (5), reduce at 30 ℃ for 60 min, and wash with ultrapure water three times to obtain the composite membrane.

[0102] An Ir loading of 1 mg cm⁻¹ was sprayed onto the Pt-impregnated side of the composite membrane. -2 The catalyst layer is coated on one side, and on the other side, a Pt loading of 0.4 mg / cm³ is sprayed on the other side. -2 The catalyst layer was used to prepare the membrane electrode.

[0103] Comparative Example 4

[0104] (1) Dissolve Pt(NH3)4(NO3)2 in water and stir thoroughly to obtain a 0.4 mM Pt(NH3)4(NO3)2 solution. Add KOH to adjust the pH to 13.

[0105] (2) Dissolve K2SO4 in water and stir thoroughly to obtain a 0.013 M K2SO4 solution. Add H2SO4 to adjust the pH to 1.

[0106] (3) The Nafion 212 membrane was treated in 0.5 M H2SO4 at 80 °C for 30 min, and then treated in ultrapure water at 80 °C for 30 min. The membrane was washed with water until pH=7 to obtain the treated membrane.

[0107] (4) According to Figure 1 The membrane was fixed in a manner in which the potassium sulfate solution obtained in step (2) was placed on the upper layer and the platinum-containing solution obtained in step (1) was placed on the lower layer. The membrane treated in step (3) was longitudinally immersed in the solution and immersed at 30 °C for 1 h.

[0108] (5) Dissolve NaBH4 in water and stir thoroughly to obtain a 0.2 M NaBH4 solution. Add KOH to adjust the pH to 11.

[0109] (6) Pour out the solutions on both sides, replace the lower layer solution with 0.2 M NaBH4 (pH=11, KOH) obtained in step (5), and reduce at 30 ℃ for 60 min;

[0110] (7) Take out the membrane obtained in step (6), wash it three times with ultrapure water, treat it with 5 M HClO4 at room temperature for 48 h, treat it with ultrapure water at 80 ℃ for 30 min, and then wash it with ultrapure water to obtain the composite membrane.

[0111] An Ir loading of 1 mg cm⁻¹ was sprayed onto the Pt-impregnated side of the composite membrane. -2 The catalyst layer is coated on one side, and on the other side, a Pt loading of 0.4 mg / cm³ is sprayed on the other side. -2 The catalyst layer was used to prepare the membrane electrode.

[0112] Comparative Example 5

[0113] (1) Dissolve Pd(NH3)4(NO3)2 in water and stir thoroughly to obtain a 0.4 mM Pd(NH3)4(NO3)2 solution. Add KOH to adjust the pH to 13.

[0114] (2) Dissolve K2SO4 in water and stir thoroughly to obtain a 0.013 M K2SO4 solution. Add H2SO4 to adjust the pH to 1.

[0115] (3) The Nafion 212 membrane was treated in 0.5 M H2SO4 at 80 °C for 30 min, and then treated in ultrapure water at 80 °C for 30 min. The membrane was washed with water until pH=7 to obtain the treated membrane.

[0116] (4) According to Figure 1 The membrane was fixed in a manner in which the potassium sulfate solution obtained in step (2) was placed in the lower layer and the palladium-containing solution obtained in step (1) was placed in the upper layer. The membrane treated in step (3) was longitudinally immersed in the solution and immersed at 30 °C for 1 h.

[0117] (5) Dissolve NaBH4 in water and stir thoroughly to obtain a 0.2 M NaBH4 solution. Add KOH to adjust the pH to 13.

[0118] (6) Pour out the solutions on both sides, replace the upper solution with 0.2 M NaBH4 (pH=11, KOH) obtained in step (5), and reduce at 30 ℃ for 60 min;

[0119] (7) Take out the membrane obtained in step (6), wash it three times with ultrapure water, treat it with 1 M H2SO4 at room temperature for 48 h, treat it with ultrapure water at 80 ℃ for 30 min, and then wash it with ultrapure water to obtain the composite membrane.

[0120] An Ir loading of 1 mg cm⁻¹ was sprayed onto the Pd-impregnated side of the composite membrane. -2 The catalyst layer is coated on one side, and on the other side, a Pt loading of 0.4 mg / cm³ is sprayed on the other side. -2 The catalyst layer was used to prepare the membrane electrode.

[0121] like Figure 3 As shown, due to gravity, the Pt in the composite membrane in Comparative Example 2 is concentrated in the lower layer; due to the generation of bubbles, the Pt in the composite membrane in Comparative Example 4 is distributed in a dotted pattern, making it impossible to achieve a uniform distribution throughout the membrane; Example 1 utilizes the upper layer reduction to effectively remove the gas generated by reduction, and at the same time utilizes the longitudinal distribution to eliminate the influence of gravity in membrane impregnation, thereby achieving a uniform distribution of noble metals in the composite membrane.

[0122] The loading of the composite membrane hydrogen removal catalyst in Examples 1-3 and Comparative Examples 1-5 was tested, and a full cell was assembled for water electrolysis tests. The current density at 1.8V and the current density at 500mA cm⁻¹ were measured. -2 The hydrogen content in the anolyte at the given current density is shown in Table 1.

[0123] Table 1 Test results of Examples 1-3 and Comparative Examples 1-5

[0124]

[0125] Depend on Figure 4 As can be seen from the comparison with Comparative Example 1, the composite membranes prepared by the impregnation method in Examples 1 and 2 utilize the impregnation of hydrogen-removing catalysts to oxidize hydrogen diffused to the anode side in situ, effectively reducing the hydrogen content in the oxygen on the anode side. This significantly improves the safety of battery operation and avoids the risk of explosion. Furthermore, Table 1 shows that longitudinal impregnation of precious metals has no significant impact on the overall battery performance. However, Comparative Example 3, lacking acid washing, exhibits a significantly increased membrane resistance and a marked decrease in battery performance. In Comparative Example 5, the addition of KOH affects the pH of the solution, resulting in poor Pd deposition. After acid washing, the remaining impregnation amount is almost zero, failing to achieve the hydrogen removal function.

[0126] For anyone skilled in the art, many possible variations and modifications can be made to the technical solutions of this invention, or equivalent embodiments can be modified based on the disclosed technical content, without departing from the scope of the technical solutions of this invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solutions of this invention should still fall within the protection scope of the technical solutions of this invention.

Claims

1. A method for preparing a composite proton exchange membrane, characterized by, The method comprises the following steps: (1) dissolving a compound containing noble metal ions in water, adjusting the pH to 7-13 after fully stirring and dissolving to obtain a solution S1; (2) dissolving K2SO4 in water, adjusting the pH to 1-3 after fully stirring and dissolving to obtain a solution S2; (3) acid washing and water washing a proton exchange membrane M1 to obtain an activated membrane M2; (4) adding the solution S1 and the solution S2 to the two sides of the activated membrane M2 to obtain a membrane M3 by longitudinal immersion; the longitudinal direction refers to that the membrane is parallel to the bottom of the immersion container, and the solution S1 and the solution S2 are located on the upper and lower sides of the membrane, respectively; (5) dissolving NaBH4 in water, adjusting the pH to 7-13 after fully stirring and dissolving to obtain a solution S3; (6) adding the solution S3 to the upper side of the membrane M3 for reduction treatment to obtain a membrane M4; (7) acid washing and water washing the membrane M4 to obtain the composite proton exchange membrane; In the step (1), the molar concentration of the compound containing noble metal ions in the solution S1 is 0.4-4 mM; KOH is used to adjust the pH; In the step (2), the molar concentration of K2SO4 in the solution S2 is 0.01-0.1 M; H2SO4 is used to adjust the pH; In the step (3), the acid used for acid washing is 0.5 M H2SO4; In the step (5), the molar concentration of NaBH4 in the solution S3 is 0.2-1 M; KOH is used to adjust the pH; In the step (7), the acid used for acid washing is HClO4 or H2SO4, and the molar concentration thereof is 1-5 M; In the step (1), the compound containing noble metal ions is one or more of Pt(NH3)4(NO3)2, Pt(NH3)4Cl2, Pd(NH3)4(NO3)2 and Pd(NH3)4Cl2; When the compound containing noble metal ions is a Pt compound, the pH in the steps (1) and (5) is independently 10-13; when the compound containing noble metal ions is a Pd compound, the pH in the steps (1) and (5) is independently 7-11; when the compound containing noble metal ions is a combination of a Pt compound and a Pd compound, the pH in the steps (1) and (5) is independently 10-11.

2. The method for preparing a composite proton exchange membrane according to claim 1, characterized by, In the step (3), the temperature for acid washing and water washing is 80 ℃, the acid washing time is 30-60 min, and the water washing time is 30-60 min; In the step (4), the immersion temperature is 30-40 ℃, and the immersion time is 1-24 h; In the step (6), the reduction temperature is 30-40 ℃, and the reduction time is 30-90 min; In the step (7), the temperature for acid washing is 20 ℃, the acid washing time is 12-48 h, the temperature for water washing is 80 ℃, and the water washing time is 30-60 min.

3. A composite proton exchange membrane, characterized by, Prepared by the method of any one of claims 1-2.

4. A membrane electrode comprising a composite proton exchange membrane, and an anode catalytic layer and a cathode catalytic layer on the side of the noble metal impregnation, respectively, characterized in that, The composite proton exchange membrane is the composite proton exchange membrane of claim 3.

5. The membrane electrode according to claim 4, characterized in that, The anode catalytic layer comprises an anode catalyst and ionomer 1, the anode catalyst comprises one or more of Ir-based catalyst, Ru-based catalyst and IrRu composite catalyst, the ionomer 1 is a perfluorosulfonic acid resin; The cathode catalytic layer comprises a cathode catalyst and ionomer 2, the cathode catalyst comprises one or more of Pt-based catalyst and Pd-based catalyst, the ionomer 2 is a perfluorosulfonic acid resin.

6. The membrane electrode according to claim 5, characterized in that, The anode catalyst comprises Ir, IrOx, Ru, RuOx, IrRuOx, IrY alloy, RuY alloy, IrRuY alloy and corresponding catalysts with carriers, wherein Y is selected from one or more of Pt, Pd, Au, Ag, Fe, Co, Ni, Cu and Mn; The carrier comprises one or more of carbon, titanium dioxide and tungsten oxide.

7. The membrane electrode according to claim 5, characterized in that, The Pt-based catalyst comprises one or more of Pt / C, Pt and PtM alloy, and the Pd-based catalyst comprises one or more of Pd / C, Pd and PdM alloy, wherein M is selected from one or more of Ir, Ru, Au, Co, Fe, Cu and Ni.

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