A low-load IrO2 water electrolysis membrane electrode, its preparation method and its application

Abstract

The application provides a low-loading IrO2 electrolytic water membrane electrode, a preparation method and application thereof, and the preparation method comprises the following steps: S1, dispersing iridium dioxide and a polymer in a mixed solution to obtain a spinning precursor solution; the mixed solution comprises a Nafion solution, water and isopropyl alcohol; S2, performing electrostatic spinning on the spinning precursor solution to obtain an IrO2 nanofiber layer; S3, performing hot pressing transfer printing on the Nafion membrane to form an anode catalytic layer; S4, spraying a cathode catalyst slurry on the other side of the Nafion membrane, and performing hot pressing to form a cathode catalytic layer, and finally obtaining the low-loading IrO2 electrolytic water membrane electrode. The low-loading IrO2 electrolytic water membrane electrode with high ordering degree, uniform and controllable fiber diameter and uniform catalyst particle distribution is constructed, the utilization rate of the catalyst is improved while the loading of the noble metal catalyst is reduced, the three-phase interface of the membrane electrode is enlarged, and the high activity is achieved in water electrolysis catalysis.

Description

Technical Field

[0001] This invention belongs to the field of preparation technology of water electrolysis membrane electrodes, and in particular relates to a low-load IrO2 water electrolysis membrane electrode, its preparation method and its application. Background Technology

[0002] Proton exchange membrane electrolysis (PEMWE) has attracted considerable attention from researchers due to its advantages such as high energy density and high hydrogen production purity. Among these advancements, iridium-based materials play a crucial role in PEMWE as highly efficient electrocatalysts for the oxygen evolution reaction (OER). However, because iridium is relatively scarce and expensive on Earth, large-scale application of PEMWE requires reducing the amount of iridium used to maintain high performance even at low loading levels.

[0003] Membrane electrode assembly (MEA), also known as membrane electrode, is a key core component of PEMWE (Potential Electrode Environment), serving as a crucial site for mass transfer and electrochemical reactions. The MEA consists of three parts from the inside out: a proton exchange membrane, a catalyst layer, and a gas diffusion layer. The traditional method involves directly spraying the catalyst (CCM) onto the proton exchange membrane, resulting in a high catalyst loading (2–4 mg / cm³) on the prepared MEA. -2 Furthermore, due to the dense packing of the catalyst layer particles, the mass transport efficiency is poor, requiring further optimization. Increasing the three-phase reaction interface of the membrane electrode to improve catalyst utilization is one of the effective methods to reduce the amount of precious metal catalysts used.

[0004] Therefore, the overall design of controllable membrane electrode construction to maximize the three-phase reaction interface, expand the proton exchange membrane / catalytic layer interface, and create a fast mass transfer channel is currently a research hotspot and challenge. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a low-loading IrO2 water electrolysis membrane electrode, its preparation method and its application, to solve the problems of low catalyst utilization, resulting in high catalyst loading on the membrane electrode, and poor material transport efficiency at the three-phase reaction interface of the membrane electrode in the prior art.

[0006] To achieve the above and other related objectives, the present invention provides a method for preparing a low-load IrO2 water electrolysis membrane electrode, the method comprising the following steps:

[0007] S1. Iridium dioxide and polymer are dispersed in a mixed solution to obtain a uniform spinning precursor solution; wherein, the mixed solution includes Nafion solution, water and isopropanol;

[0008] S2. Electrospin the spinning precursor solution to obtain an IrO2 nanofiber layer on a receiving device.

[0009] S3. The IrO2 nanofiber layer is hot-pressed onto the Nafion membrane to form an anode catalyst layer on the Nafion membrane;

[0010] S4. The cathode catalyst slurry is sprayed onto the side of the Nafion membrane away from the anode catalyst layer. After hot pressing, a cathode catalyst layer is formed on the other side of the Nafion membrane, and finally a low-load IrO2 water electrolysis membrane electrode is prepared.

[0011] Preferably, the polymer in step S1 includes one of polyethylene oxide, polyvinyl alcohol, polyacrylonitrile, and polyvinylpyrrolidone, and the viscosity-average molecular weight of the polymer is 100,000 to 1,000,000.

[0012] Preferably, the mass ratio of iridium dioxide, polymer, and Nafion solution in step S1 is (20-100):(2-20):(50-500), and the mass concentration of the polymer in the obtained spinning precursor solution is 2wt%-10wt%.

[0013] Preferably, in step S1, the total mass of water and isopropanol is 0 to 30 times the mass of iridium dioxide, and the mass ratio of water to isopropanol is 1:1.

[0014] Preferably, the Nafion solution in step S1 is a Nafion solution with a mass percentage of 5 wt% or 20 wt%.

[0015] Preferably, the electrospinning process parameters in step S2 are: positive voltage of 4-20kV, negative voltage of 0--3kV, ambient temperature of 15-25℃, relative humidity of 35%-45%, solution propulsion speed of 0.01-0.3ml / h, and distance between syringe needle and receiving device of 10-20cm.

[0016] Preferably, the receiving device in step S2 is a flat, grid, or roller-shaped receiving device, and aluminum foil or silicone paper is adhered to the receiving device.

[0017] Preferably, the Nafion membrane in step S3 needs to be pretreated before transfer. Specifically, the Nafion membrane is cut to the required size, placed in a 3wt% to 10wt% hydrogen peroxide solution and heated for 1 hour, then washed with ultrapure water, and then placed in a 0.5mol / L sulfuric acid solution and heated for 1 hour. After washing with ultrapure water, a pure Nafion membrane is obtained.

[0018] Preferably, the temperature of the hot pressing transfer in step S3 is 130-140°C, the pressure of the hot pressing transfer is 1-3 MPa, and the time of the hot pressing transfer is 2-5 min.

[0019] Preferably, in step S4, the cathode catalyst slurry comprises 1 part Pt / C catalyst, 1 to 10 parts 5 wt% Nafion solution, 5 to 15 parts water and 5 to 15 parts isopropanol, based on the composition of the cathode catalyst slurry.

[0020] Preferably, the hot pressing temperature in step S4 is 130-140°C, the hot pressing pressure is 4-6 MPa, and the hot pressing time is 1-3 min.

[0021] Preferably, the loading of the cathode catalyst layer formed in step S4 on the Nafion film is 0.3–0.6 mg / cm³. 2 .

[0022] Preferably, the Pt / C catalyst is composed of two substances, Pt and C, wherein the mass percentage of Pt in the Pt / C catalyst is 40wt% to 60wt%.

[0023] The present invention also provides a low-load IrO2 water electrolysis membrane electrode, wherein the membrane electrode is prepared by the above-described preparation method of the low-load IrO2 water electrolysis membrane electrode.

[0024] The present invention also provides an application of a low-load IrO2 water electrolysis membrane electrode, wherein the membrane electrode is used in a proton exchange membrane water electrolysis catalytic reaction, and the membrane electrode is prepared by the above-described method for preparing a low-load IrO2 water electrolysis membrane electrode.

[0025] As described above, the low-load IrO2 water electrolysis membrane electrode, its preparation method, and its application of the present invention have the following beneficial effects:

[0026] This invention employs electrospinning technology to obtain a uniform fibrous IrO2 nanofiber layer, with the noble metal catalyst located on the fiber surface, making it less prone to aggregation. This reduces the noble metal catalyst loading while improving catalyst utilization. Furthermore, this invention uses Nafion as the fiber skeleton for the anode catalyst layer, obtaining a uniform and continuous three-dimensional network structure of IrO2 nanofibers. This layer is then hot-pressed onto a Nafion membrane to form the anode catalyst layer. A cathode catalyst layer is then sprayed onto the other side of the Nafion membrane, thereby efficiently and directly constructing a low-loading IrO2 water electrolysis membrane electrode with a high degree of order, uniform and controllable fiber diameter, and uniform catalyst particle distribution. Moreover, the three-dimensional network structure of this membrane electrode expands the three-phase interface, enhancing mass transport during water electrolysis. The formed continuous proton transport channels effectively improve proton conduction and reduce mass transfer loss. The prepared low-loading IrO2 water electrolysis membrane electrode exhibits high activity in the proton exchange membrane water electrolysis catalytic reaction. Attached Figure Description

[0027] Figure 1 The image shown is a SEM image of the IrO2 nanofiber layer prepared in Example 1 of this invention.

[0028] Figure 2 The image shown is a TEM image of a single fiber in the IrO2 nanofiber layer prepared in Example 1 of this invention.

[0029] Figure 3 The images shown are high-angle annular dark-field transmission electron microscopy (HAADF-TEM) images and energy-dispersive spectroscopy (EDS) mappings of a single fiber in the IrO2 nanofiber layer prepared in Example 1 of this invention.

[0030] Figure 4 The diagram shows the polarization curves of the membrane electrodes prepared in Examples 1, 2 and 3 of this invention.

[0031] Figure 5 The graphs shown are stability test curves of the membrane electrodes prepared in Examples 1, 2 and 3 of this invention. Detailed Implementation

[0032] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0033] This invention provides a method for preparing a low-load IrO2 water electrolysis membrane electrode, the method comprising the following steps:

[0034] S1. Iridium dioxide and polymer are dispersed in a mixed solution to obtain a uniform spinning precursor solution; wherein the mixed solution includes Nafion solution, water and isopropanol; the dispersion method is to disperse by ultrasonic and / or magnetic stirring, preferably, the dispersion is ultrasonic dispersion for 1-3 hours and / or magnetic stirring dispersion for 1-3 hours;

[0035] S2. Electrospin the spinning precursor solution to obtain an IrO2 nanofiber layer on a receiving device.

[0036] S3. The IrO2 nanofiber layer is hot-pressed onto the Nafion membrane to form an anodic catalyst layer on the Nafion membrane.

[0037] S4. The cathode catalyst slurry is sprayed onto the side of the Nafion membrane away from the anode catalyst layer. After hot pressing, a cathode catalyst layer is formed on the other side of the Nafion membrane, and finally a low-load IrO2 water electrolysis membrane electrode is prepared.

[0038] Specifically, in step S2, aluminum foil or silicone paper is adhered to the receiving device to control the spinning time. After spinning is completed, the aluminum foil or silicone paper on the receiving device is peeled off and then cut into a size consistent with the size of the Nafion membrane in step S3. The actual loading of the IrO2 nanofiber layer is obtained by weighing the aluminum foil or silicone paper before and after spinning.

[0039] In a specific embodiment of the present invention, a uniform fibrous IrO2 nanofiber layer is obtained using electrospinning technology, and the noble metal catalyst IrO2 is located on the fiber surface, making it less prone to agglomeration. This reduces the noble metal catalyst loading while improving catalyst utilization. Furthermore, Nafion is used as the fiber skeleton of the anode catalyst layer to obtain a uniform and continuous three-dimensional network structure of IrO2 nanofibers. This layer is then hot-pressed onto a Nafion membrane to form the anode catalyst layer. A cathode catalyst layer is then sprayed onto the other side of the Nafion membrane, thereby efficiently and directly constructing a low-loading IrO2 water electrolysis membrane electrode with a high degree of ordering, uniform and controllable fiber diameter, and uniform catalyst particle distribution. As an example, the polymer in step S1 includes one of polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), and polyvinylpyrrolidone (PVP), and the viscosity-average molecular weight of the polymer is 100,000 to 1,000,000.

[0040] Specifically, the viscosity-average molecular weight of polymers can include any value within a range such as 100,000, 300,000, 600,000, 1,000,000, and should be adjusted according to actual conditions.

[0041] As an example, in step S1, the mass ratio of iridium dioxide, polymer, and Nafion solution is (20-100):(2-20):(50-500), and the mass concentration of polymer in the obtained spinning precursor solution is 2wt%-10wt%.

[0042] Specifically, the mass ratio of iridium dioxide, polymer, and Nafion solution can be any value within the range of 20:2:50, 20:20:50, 20:2:500, 20:20:500, 100:2:50, 100:2:50, 100:20:50, 100:20:50, etc.; the mass concentration of polymer in the obtained spinning precursor solution can be any value within the range of 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, etc., and should be adjusted according to the actual situation.

[0043] As an example, in step S1, the total mass of water and isopropanol is 0 to 30 times the mass of iridium dioxide, and the mass ratio between water and isopropanol is 1:1.

[0044] Specifically, the total mass of water and isopropanol is 0, 5, 10, 15, 20, 25, or 30 times the mass of iridium dioxide. The amount of water and isopropanol added depends on the viscosity of the spinning precursor solution. It is necessary to ensure that the mass concentration of polymer in the spinning precursor solution is 2wt% to 10wt%. If the mass concentration of polymer in the spinning precursor solution is appropriate, there is no need to add water and isopropanol. If the mass concentration of polymer in the spinning precursor solution is not in the range of 2wt% to 10wt%, then water and isopropanol need to be added.

[0045] As an example, the Nafion solution in step S1 is a Nafion solution with a mass percentage of 5 wt% or 20 wt%.

[0046] Specifically, the preparation method of Nafion solution usually involves adding Nafion polymer to water and then dissolving it by stirring and heating; in a specific embodiment of the present invention, the Nafion polymer is a perfluorosulfonic acid-polytetrafluoroethylene copolymer.

[0047] As an example, the process parameters for electrospinning in step S2 are: positive voltage of 4-20kV, negative voltage of 0-3kV, ambient temperature of 15-25℃, relative humidity of 35%-45%, solution propulsion speed of 0.01-0.3ml / h, and distance between syringe needle and receiving device of 10-20cm.

[0048] Specifically, electrospinning is performed using an electrospinning machine. The pre-spinning precursor solution is injected into a syringe, which is then placed on the injection pump of the electrospinning machine. The distance between the syringe needle and the receiving device is set, and other parameters are then set to control the spinning time. In this specific embodiment of the invention, the electrospinning process is performed using a method well-known to those skilled in the art, but the process parameters need to be specifically limited. The positive voltage can include values ​​within any range such as 4kV, 8kV, 12kV, 16kV, and 20kV, and the negative voltage can include -0.1kV, -0.5kV, -1kV, -2kV, and -3kV. The values ​​can be within any range, including ambient temperature (15℃, 18℃, 20℃, 22℃, 25℃, etc.), relative humidity (35%, 37%, 39%, 40%, 42%, 45%), solution propulsion speed (0.01ml / h, 0.05ml / h, 0.1ml / h, 0.2ml / h, 0.3ml / h, etc.), and distance between syringe needle and receiving device (10cm, 12cm, 14cm, 16cm, 18cm, 20cm, etc.). The specific values ​​can be adjusted according to actual needs.

[0049] In addition, electrospinning machines generate a high-voltage electric field when in operation. Safety education and training must be conducted before electrospinning, and the experimental process must be closely monitored during use to ensure personal and instrument safety.

[0050] As an example, in step S2, the receiving device is a flat, grid, or roller-shaped receiving device, and aluminum foil or silicone paper is adhered to the receiving device.

[0051] Specifically, the receiving device is used to receive the IrO2 nanofibers formed by electrospinning. A flat receiving device or a grid receiving device is usually used. When preparing a large-area membrane electrode, a rotating roller receiving device can be used. Aluminum foil or silicone paper is attached to the receiving device so that the obtained IrO2 nanofiber layer can be peeled off from the receiving device. Then, the actual loading of the IrO2 nanofiber layer is obtained by weighing the aluminum foil or silicone paper before and after spinning.

[0052] In a specific embodiment of the present invention, the loading of the anode catalyst layer on the finally prepared low-loading IrO2 water electrolysis membrane electrode is 0.1–2 mg / cm³. 2 (e.g., 0.1 mg / cm) 2 0.3 mg / cm 2 0.5 mg / cm 2 1mg / cm 2 1.5 mg / cm 2 1.7 mg / cm 2 2mg / cm2 (Values ​​within any range).

[0053] As an example, the Nafion membrane in step S3 needs to be pretreated before transfer. Specifically, the Nafion membrane is cut to the required size, placed in a hydrogen peroxide solution of 3wt% to 10wt% (e.g., any value in the range of 3wt%, 5wt%, 7wt%, 9wt%, 10wt%) and heated for 1 hour, then washed with ultrapure water, and then placed in a 0.5mol / L sulfuric acid solution and heated for 1 hour. After washing with ultrapure water, a pure Nafion membrane is obtained.

[0054] As an example, in step S3, the temperature of hot pressing transfer is 130-140℃, the pressure of hot pressing transfer is 1-3 MPa, and the time of hot pressing transfer is 2-5 min.

[0055] Specifically, in step S3, the hot pressing transfer is performed on a hydraulic press. The IrO2 nanofiber layer with aluminum foil or silicone paper is cut to the same size as the Nafion film, and then they are placed together on the hydraulic press for hot pressing. The temperature of the hot pressing transfer can be any value within the range of 130℃, 132℃, 134℃, 136℃, 138℃, 140℃, etc., and can be adjusted according to the actual situation. The pressure of the hot pressing transfer can be any value within the range of 1Mpa, 1.5Mpa, 2Mpa, 2.5Mpa, 3Mpa, etc., and can be adjusted according to the actual situation. The time of the hot pressing transfer can be any value within the range of 2min, 3min, 4min, 5min, etc., and can be adjusted according to the actual situation.

[0056] As an example, in step S4, based on the composition of the cathode catalyst slurry, the cathode catalyst slurry includes 1 part Pt / C catalyst, 1 to 10 parts (e.g., 1 part, 3 parts, 5 parts, 7 parts, 9 parts, 10 parts, etc.) 5 wt% Nafion solution, 5 to 15 parts (e.g., 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, etc.) water and 5 to 15 parts (e.g., 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, etc.) isopropanol.

[0057] Specifically, the cathode catalyst slurry is prepared by ultrasonically dispersing a certain proportion of Pt / C catalyst, 5wt% Nafion solution, water, and isopropanol.

[0058] As an example, in step S4, the hot pressing temperature is 130-140°C, the hot pressing pressure is 4-6 MPa, and the hot pressing time is 1-3 min.

[0059] Specifically, the hot pressing in step S4 is also performed on a hydraulic press. The hot pressing temperature can be any value within the range of 130℃, 132℃, 134℃, 136℃, 138℃, 140℃, etc., and can be adjusted according to the actual situation. The hot pressing pressure can be any value within the range of 4Mpa, 4.5Mpa, 5Mpa, 5.5Mpa, 6Mpa, etc., and can be adjusted according to the actual situation. The hot pressing time can be any value within the range of 1min, 1.5min, 2min, 2.5min, 3min, etc., and can be adjusted according to the actual situation.

[0060] As an example, the cathode catalyst layer formed in step S4 has a loading of 0.3–0.6 mg / cm³ on the Nafion membrane. 2 .

[0061] Specifically, the loading of the formed cathode catalyst layer on the Nafion membrane may include 0.3 mg / cm³. 2 0.4 mg / cm 2 0.5 mg / cm 2 0.6 mg / cm 2 Values ​​within any range, which can be adjusted according to actual conditions.

[0062] As an example, a Pt / C catalyst is composed of two substances, Pt and C, wherein the mass percentage of Pt in the Pt / C catalyst is 40wt% to 60wt% (e.g., any value within the range of 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, etc.).

[0063] The present invention also provides a low-load IrO2 water electrolysis membrane electrode, which is prepared by the above-described method for preparing a low-load IrO2 water electrolysis membrane electrode.

[0064] In addition, the present invention also provides an application of a low-load IrO2 water electrolysis membrane electrode, which is used in a proton exchange membrane water electrolysis catalytic reaction.

[0065] To better understand the low-load IrO2 water electrolysis membrane electrode, its preparation method, and its application in this invention, the following description, with reference to specific embodiments, illustrates the low-load IrO2 water electrolysis membrane electrode, its preparation method, and its application. It should be noted that these embodiments are merely descriptive and do not limit the invention in any way.

[0066] Example 1

[0067] This embodiment provides a method for preparing a low-load IrO2 water electrolysis membrane electrode, which includes the following steps:

[0068] S1. Add 80 mg of iridium dioxide and 14 mg of PEO to a sample bottle, then add 185 mg of ultrapure water, 99 mg of 5 wt% Nafion solution and 185 mg of isopropanol in sequence. Stir magnetically for 2 h to make IrO2 uniformly dispersed to obtain a homogeneous spinning precursor solution; wherein, the viscosity-average molecular weight of PEO is 600,000.

[0069] S2. Inject 1 mL of the spinning precursor solution into a syringe, then place the syringe on the injection pump of the electrospinning machine, ensuring a distance of 15 cm between the syringe needle and the flat receiving device. Under the conditions of an external positive voltage of 15 kV, a negative voltage of -2 kV, an ambient temperature of 20°C, and a relative humidity of 40%, electrospinning is performed at a solution feed rate of 0.15 ml / h. After 10 minutes, an IrO2 nanofiber layer is obtained on the flat receiving device. The flat receiving device has aluminum foil adhered to it, and the IrO2 nanofiber film is attached to the aluminum foil. The aluminum foil is peeled off the flat receiving device and cut into 2 cm × 2 cm shapes. By weighing the aluminum foil before electrospinning, the actual loading of the IrO2 nanofiber layer is calculated to be 0.1 mg / cm³. 2 ;

[0070] S3. Place the IrO2 nanofiber layer attached to the aluminum foil and a 2cm×2cm Nafion film tightly on a hydraulic press. Set the hot-press transfer temperature to 135℃ and the hot-press transfer pressure to 2MPa. Perform the hot-press transfer for 3 minutes to transfer the IrO2 nanofiber layer onto the Nafion film, forming an anode catalyst layer on the Nafion film. The Nafion film used is a Nafion 115 film.

[0071] S4. The cathode catalyst slurry is sprayed onto the side of the Nafion membrane away from the anode catalyst layer using an airbrush. It is then hot-pressed on a hydraulic press at a temperature of 135°C, a pressure of 6 MPa, and a pressing time of 2 min to form a cathode catalyst layer on the other side of the Nafion membrane. This process ultimately produces a low-load IrO2 water electrolysis membrane electrode. The cathode catalyst slurry is composed of 15 mg of 60% Pt / C catalyst, 75 mg of 5% Nafion solution, 225 mg of water, and 225 mg of isopropanol.

[0072] The low-loading IrO2 water electrolysis membrane electrode prepared in this embodiment includes a Nafion membrane, an anode catalyst layer, and a cathode catalyst layer. The actual loading of the anode catalyst layer is 0.1 mg / cm³. 2 In this embodiment, the prepared low-load IrO2 electrolytic water membrane electrode is simply referred to as ES-0.1.

[0073] See Figure 1 , Figure 2 , Figure 1 This is a SEM image of the IrO2 nanofiber layer prepared in this embodiment. Figure 2 The image shows a TEM image of a single fiber in the IrO2 nanofiber layer. As can be seen from the image, the IrO2 nanofiber layer prepared in this embodiment forms a uniform network skeleton. The fibers are complete, uniform, and free from agglomeration. When used in the electrolysis of water catalysis, it can effectively promote the transport of oxygen and water. In addition, the uniform distribution of IrO2 on the fiber surface increases the number of reactive sites, which can improve the utilization rate of the catalyst while reducing the loading of noble metal catalyst.

[0074] See Figure 3 The images show high-angle annular dark-field transmission electron microscopy (HAADF-TEM) and energy-dispersive spectroscopy (EDS) mapping of a single fiber in the IrO2 nanofiber layer prepared in this embodiment. From left to right and top to bottom, the first image is a high-angle annular dark-field scanning transmission electron microscopy image, the second image is a combined image of O, F, S, and Ir elements, and the rest are elemental analysis images of O, F, S, and Ir in sequence. As can be seen from the images, the IrO2 catalyst particles are distributed uniformly on the fiber surface without aggregation. At the same time, the Nafion resin is uniformly distributed, forming a continuous proton transport channel.

[0075] Compare with Example 1

[0076] This comparative example provides a conventional method for preparing a membrane electrode, which includes the following steps:

[0077] A1. Add 5 mg of iridium dioxide to the sample bottle, then add 75 mg of ultrapure water, 25 mg of 5 wt% Nafion solution and 75 mg of isopropanol in sequence, and sonicate for 2 h to make IrO2 uniformly dispersed to obtain a homogeneous anode catalyst slurry.

[0078] A2. The anode catalyst slurry is sprayed onto the Nafion membrane using an airbrush and then hot-pressed (hot-pressing temperature is 135℃, hot-pressing pressure is 6Mpa, hot-pressing is performed for 2min) to form an anode catalyst layer on the Nafion membrane.

[0079] A3. The cathode catalyst slurry is sprayed onto the side of the Nafion membrane away from the anode catalyst layer using an airbrush. It is then hot-pressed on a hydraulic press at a temperature of 135°C, a pressure of 6 MPa, and a pressing time of 2 minutes to form a cathode catalyst layer on the other side of the Nafion membrane. This process ultimately produces a conventional membrane electrode. The cathode catalyst slurry is composed of 15 mg of 60% Pt / C catalyst, 75 mg of 5% Nafion solution, 225 mg of water, and 225 mg of isopropanol.

[0080] The actual loading of the anodic catalyst layer on the membrane electrode prepared in this comparative example was 0.1 mg / cm³. 2 In this comparative example, the prepared membrane electrode is referred to simply as CCM-0.1.

[0081] Example 2

[0082] This comparative example provides a method for preparing a low-load IrO2 water electrolysis membrane electrode. The difference between this method and that in Comparative Example 1 is that in step A1, 20 mg of iridium dioxide is added to a sample bottle, followed by the sequential addition of 300 mg of ultrapure water, 100 mg of 5 wt% Nafion solution, and 300 mg of isopropanol. The mixture is then ultrasonically dispersed for 2 hours to ensure uniform dispersion of IrO2 and obtain a homogeneous anode catalyst slurry. Other steps and methods are the same as in Comparative Example 1 and will not be repeated here.

[0083] The actual loading of the anodic catalyst layer on the membrane electrode prepared in this comparative example was 0.1 mg / cm³. 2 In this comparative example, the prepared membrane electrode is referred to simply as CCM-1.

[0084] Application Example 1

[0085] This application example provides an application of a membrane electrode, in which the membrane electrodes (ES-0.1, CCM-0.1, CCM-1) prepared in Example 1, Comparative Example 1 and Comparative Example 2 are applied to a proton exchange membrane water electrolysis catalytic reaction.

[0086] Polarization curve test:

[0087] Each membrane electrode (ES-0.1, CCM-0.1, CCM-1) was placed in a small water electrolysis fixture. Deionized pure water at 80°C was passed through the anode, and the entire system was kept at 80°C. The current density for water electrolysis was set to 0–2 A / cm². 2 Tests were conducted to obtain the polarization curves of each membrane electrode during water electrolysis. (Refer to...) Figure 4 As shown, by Figure 4 It can be seen that the IrO2 catalyst loading in ES-0.1 is comparable to, and slightly better than, that of the traditional CCM-1 when reduced by a factor of ten; while the performance of CCM-0.1 with the same catalyst loading is very poor. This indicates that the membrane electrode prepared in this invention can effectively improve the utilization rate of the water electrolysis catalyst and improve the reaction performance.

[0088] Stability test:

[0089] Each membrane electrode (ES-0.1, CCM-0.1, CCM-1) was placed in a small water electrolysis fixture and its stability was tested at 80°C. During the test, ultrapure water was passed through the anode, and the current density was set to 1 A / cm². 2The stability test results are available in the reference section. Figure 5 As shown, by Figure 5 It can be seen that after 100 hours of operation, the performance of ES-0.1 remains good, similar to that of CCM-1. However, the stability of CCM-0.1 deteriorates rapidly with the extension of operating time, and it stops after about 20 hours of operation due to reaching the protection voltage.

[0090] In summary, this invention utilizes electrospinning technology to obtain a uniform fibrous IrO2 nanofiber layer, with the noble metal catalyst located on the fiber surface, making aggregation less likely. This reduces the noble metal catalyst loading while improving catalyst utilization. Furthermore, this invention uses Nafion as the fiber skeleton for the anode catalyst layer, obtaining a uniform and continuous three-dimensional network structure of IrO2 nanofibers. This layer is then hot-pressed onto a Nafion membrane to form the anode catalyst layer. A cathode catalyst layer is then sprayed onto the other side of the Nafion membrane, thus efficiently and directly constructing a low-loading IrO2 water electrolysis membrane electrode with a high degree of order, uniform and controllable fiber diameter, and uniform catalyst particle distribution. Moreover, the three-dimensional network structure of this membrane electrode expands the three-phase interface, enhancing mass transport during water electrolysis. The formed continuous proton transport channels effectively improve proton conduction and reduce mass transfer loss. The prepared low-loading IrO2 water electrolysis membrane electrode exhibits high activity in the proton exchange membrane water electrolysis catalytic reaction. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0091] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing a low-load IrO2 water electrolysis membrane electrode, characterized in that, The preparation method includes the following steps: S1. Iridium dioxide and polymer are dispersed in a mixed solution to obtain a homogeneous spinning precursor solution; wherein, the mixed solution includes Nafion solution, water and isopropanol; the mass ratio of iridium dioxide, polymer and Nafion solution is (20-100):(2-20):(50-500), and the mass concentration of polymer in the obtained spinning precursor solution is 2wt%-10wt%. S2. Electrospin the spinning precursor liquid to obtain an IrO2 nanofiber layer on a receiving device. S3. The IrO2 nanofiber layer is hot-pressed onto the Nafion membrane to form an anode catalyst layer on the Nafion membrane; the hot-pressing temperature is 130-140°C, the hot-pressing pressure is 1-3 MPa, and the hot-pressing time is 2-5 min. S4. The cathode catalyst slurry is sprayed onto the side of the Nafion membrane away from the anode catalyst layer. After hot pressing, a cathode catalyst layer is formed on the other side of the Nafion membrane, and finally a low-load IrO2 water electrolysis membrane electrode is prepared.

2. The method for preparing a low-load IrO2 water electrolysis membrane electrode according to claim 1, characterized in that: Step S1 includes one or a combination of the following conditions: The polymer includes one of polyethylene oxide, polyvinyl alcohol, polyacrylonitrile, and polyvinylpyrrolidone, and the viscosity-average molecular weight of the polymer is 100,000 to 1,000,000. The total mass of water and isopropanol is 0 to 30 times the mass of iridium dioxide, and the mass ratio of water to isopropanol is 1:

1. The Nafion solution is a Nafion solution with a mass percentage of 5 wt% or 20 wt%.

3. The method for preparing a low-load IrO2 water electrolysis membrane electrode according to claim 1, characterized in that: The electrospinning process parameters in step S2 are as follows: positive voltage is 4-20kV, negative voltage is 0-3kV, ambient temperature is 15-25℃, relative humidity is 35%-45%, solution propulsion speed is 0.01-0.3ml / h, and the distance between the syringe needle and the receiving device is 10-20cm.

4. The method for preparing a low-load IrO2 water electrolysis membrane electrode according to claim 1, characterized in that: The receiving device in step S2 is a flat, grid, or roller-shaped receiving device, and aluminum foil or silicone paper is adhered to the receiving device.

5. The method for preparing a low-load IrO2 water electrolysis membrane electrode according to claim 1, characterized in that: The Nafion membrane in step S3 needs to be pretreated before transfer. Specifically, the Nafion membrane is cut to the required size, placed in a 3wt% to 10wt% hydrogen peroxide solution and heated for 1 hour, then washed with ultrapure water, and then placed in a 0.5mol / L sulfuric acid solution and heated for 1 hour. After washing with ultrapure water, a pure Nafion membrane is obtained.

6. The method for preparing a low-load IrO2 electrolytic water membrane electrode according to claim 1, characterized in that: Step S4 includes one or a combination of the following conditions: Based on the composition of the cathode catalyst slurry, the cathode catalyst slurry comprises 1 part Pt / C catalyst, 1 to 10 parts 5 wt% Nafion solution, 5 to 15 parts water and 5 to 15 parts isopropanol; The hot pressing temperature is 130-140℃, the hot pressing pressure is 4-6 MPa, and the hot pressing time is 1-3 min; The cathode catalyst layer formed has a loading of 0.3–0.6 mg / cm³ on the Nafion membrane. 2 .

7. The method for preparing a low-load IrO2 electrolytic water membrane electrode according to claim 6, characterized in that: The Pt / C catalyst is composed of two substances, Pt and C, wherein the mass percentage of Pt in the Pt / C catalyst is 40wt% to 60wt%.

8. A low-load IrO2 water electrolysis membrane electrode, characterized in that: The membrane electrode is prepared by the method described in any one of claims 1 to 7 for preparing a low-load IrO2 electrolytic water membrane electrode.

9. An application of a low-load IrO2 water electrolysis membrane electrode, characterized in that: The membrane electrode is used in the proton exchange membrane water electrolysis catalytic reaction, wherein the membrane electrode is prepared by the preparation method of the low-loading IrO2 water electrolysis membrane electrode according to any one of claims 1 to 7.

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