Anode composite catalyst layer and its slurry, preparation method, membrane electrode

Abstract

This application discloses an anode composite catalyst layer, its slurry, preparation method, and membrane electrode. The anode composite catalyst layer is located between the proton exchange membrane and the gas diffusion layer of the membrane electrode, and includes: an iridium catalyst layer having opposing first and second surfaces, wherein the first surface faces the proton exchange membrane and the second surface faces the gas diffusion layer, the iridium catalyst layer comprising a first ionomer and an iridium catalyst dispersed in the first ionomer; and a platinum conductive layer having opposing third and fourth surfaces, wherein the third surface is in contact with the second surface of the iridium catalyst layer and the fourth surface faces the gas diffusion layer, and the platinum conductive layer comprising a second ionomer and platinum nanoparticles with a particle size of 10 nm to 500 nm dispersed in the second ionomer. The anode composite catalyst layer of this application enables the membrane electrode to possess both low contact resistance and excellent stability.

Description

Technical Field

[0001] This application relates to the field of proton exchange membrane electrolysis water membrane electrode technology, specifically to an anode composite catalyst layer and its slurry, preparation method, and membrane electrode. Background Technology

[0002] A membrane electrode assembly (MEA), also known as a membrane electrode, mainly consists of a proton exchange membrane (PEM), a catalyst layer (CL), and a gas diffusion layer (GDL). The catalyst layer is the site of the electrochemical reaction and can significantly reduce the activation energy required for the reaction, thereby accelerating the rate of the electrochemical reaction.

[0003] The catalyst layer of the membrane electrode assembly includes an anode catalyst layer and a cathode catalyst layer. The anode catalyst layer can promote the hydrogen oxidation reaction (HOR), and the cathode catalyst layer can promote the oxygen reduction reaction (ORR). Both have a significant impact on the performance of the membrane electrode.

[0004] Since the performance of the membrane electrode still needs to be improved, it is still necessary to continue to improve the catalyst layer. Summary of the Invention

[0005] The purpose of this application is to provide an anode composite catalyst layer and its slurry, preparation method, and membrane electrode, so that the membrane electrode has both low contact resistance and excellent stability.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] In a first aspect, this application provides an anode composite catalyst layer located between a proton exchange membrane and a gas diffusion layer of a membrane electrode, comprising: an iridium catalyst layer having opposing first and second surfaces, wherein the first surface faces the proton exchange membrane and the second surface faces the gas diffusion layer, the iridium catalyst layer comprising a first ionomer and an iridium catalyst dispersed in the first ionomer; and a platinum conductive layer having opposing third and fourth surfaces, wherein the third surface is in contact with the second surface of the iridium catalyst layer and the fourth surface faces the gas diffusion layer, and the platinum conductive layer comprising a second ionomer and platinum nanoparticles with a particle size of 10 nm to 500 nm dispersed in the second ionomer.

[0008] In some embodiments of the first aspect, the particle size of the platinum nanoparticles is 90 nm to 120 nm; the thickness of the platinum conductive layer is 0.3 μm to 1.5 μm; and the mass ratio of the platinum nanoparticles to the second ionomer is 1:(0.35 to 0.9).

[0009] In some embodiments of the first aspect, the first ionomer and the second ionomer respectively include one or more of Nafion D2020, Nafion NR50, Aquivion D79-25B, and HCD-1820.

[0010] In some embodiments of the first aspect, the iridium catalyst is IrO2 or IrRuO2. x1 IrO2 / TiO2, IrO2 / NbO x1 IrO2 / Ta2O5, IrO2 / WO x1 or IrO2 / Nb2O 5-x2 At least one of them, wherein x1 is 1 to 2 and x2 is 0 to 3.

[0011] In a second aspect, this application provides an anode composite catalyst layer slurry, comprising: an iridium catalyst layer slurry, the iridium catalyst layer slurry comprising: an iridium catalyst, a first ionomer and a first solvent; and a platinum conductive layer slurry, the platinum conductive layer slurry comprising platinum nanoparticles with a particle size of 10 nm to 500 nm, a second ionomer and a second solvent.

[0012] In some embodiments of the second aspect, the mass ratio of the iridium catalyst, the first ionomer, and the first solvent is 1:(0.1-0.5):(5-50); the mass ratio of the platinum nanoparticles, the second ionomer, and the second solvent is 1:(0.35-0.9):(10-50).

[0013] In some embodiments of the second aspect, the first ionomer and the second ionomer respectively comprise one or more of Nafion D2020, Nafion NR50, Aquivion D79-25B, and HCD-1820; the iridium catalyst is IrO2 or IrRuO2. x IrO2 / TiO2, IrO2 / NbO x IrO2 / Ta2O5, IrO2 / WO x or IrO2 / Nb2O 5-x At least one of the following: the first solvent and the second solvent may be the same or different, and are selected from at least one of isopropanol, ethylene glycol, ethanol, n-propanol and water.

[0014] In a third aspect, this application provides a method for preparing an anode composite catalyst layer, which is prepared using the above-mentioned anode composite catalyst layer slurry.

[0015] In some embodiments of the third aspect, the preparation method includes: forming an iridium catalyst layer on the surface of a proton exchange membrane of a membrane electrode using an iridium catalyst layer slurry and by coating or transfer; forming a platinum conductive layer on the surface of the iridium catalyst layer using a platinum conductive layer slurry and by coating or transfer; or, the preparation method includes: forming a platinum conductive layer on a transfer material using a platinum conductive layer slurry and by coating or transfer; forming an iridium catalyst layer on the surface of the platinum conductive layer using an iridium catalyst layer slurry and by coating; transferring the laminated structure of the platinum conductive layer and the iridium catalyst layer to the surface of the proton exchange membrane by transfer, and removing the transfer material.

[0016] In a fourth aspect, this application provides a membrane electrode, comprising a proton exchange membrane, a gas diffusion layer, and the aforementioned anode composite catalyst layer.

[0017] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0018] This application incorporates a platinum conductive layer between an iridium catalyst layer and a gas diffusion layer. This platinum conductive layer significantly reduces the contact resistance between the iridium catalyst layer and the gas diffusion layer, and also reduces the thermal stress of the membrane electrode, thereby improving the stability of the membrane electrode. By controlling the particle size of the platinum nanoparticles in the platinum conductive layer, the contact resistance and stability of the membrane electrode can be further balanced. Attached Figure Description

[0019] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale. Wherein:

[0020] Figure 1 This is an exploded view of a membrane electrode according to one embodiment of this application;

[0021] Figure 2 This is a schematic flowchart illustrating a method for preparing an anode composite catalyst layer according to an embodiment of this application.

[0022] Figure 3 This is a schematic flowchart illustrating a method for preparing an anode composite catalyst layer according to another embodiment of this application.

[0023] Figure 4 The image shows the XRD pattern of the platinum conductive layer prepared in Example 1 of this application.

[0024] Figure 5This is a TEM image of the platinum conductive layer prepared in Example 1 of this application. Detailed Implementation

[0025] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0026] refer to Figure 1 The anode composite catalyst layer 100 provided in this application is located between the proton exchange membrane 200 and the gas diffusion layer 300 of the membrane electrode 10, and includes: an iridium catalyst layer 110 and a platinum conductive layer 120. The iridium catalyst layer 110 has a first surface 111 and a second surface 112 facing each other, wherein the first surface 111 faces the proton exchange membrane 200 and the second surface 112 faces the gas diffusion layer 300. The iridium catalyst layer 110 includes a first ionomer and an iridium catalyst dispersed in the first ionomer. The iridium catalyst layer 110 is used to promote the oxidation reaction of hydrogen.

[0027] The platinum conductive layer 120 has opposing third surfaces 121 and fourth surfaces 122, wherein the third surface 121 is in contact with the second surface 112 of the iridium catalyst layer 110, and the fourth surface 122 faces the gas diffusion layer 300. The platinum conductive layer 120 includes a second ionomer and platinum nanoparticles dispersed in the second ionomer. The platinum conductive layer 120 can significantly reduce the contact resistance between the iridium catalyst layer 110 and the gas diffusion layer 300, allowing electrons to flow rapidly from the iridium catalyst layer 110 to the gas diffusion layer 300, thereby increasing the current density of the proton exchange membrane electrolysis water electrolysis electrode. Simultaneously, the platinum conductive layer 120 can also optimize the interface structure between the iridium catalyst layer 110 and the gas diffusion layer 300, thereby enhancing the gas diffusion effect, helping to reduce polarization during the anodic reaction process, and allowing more oxygen produced by the reaction to diffuse rapidly into the flow field. Therefore, the introduction of the platinum conductive layer 120 can effectively improve the performance of the proton exchange membrane electrolysis water electrolysis electrode.

[0028] The introduction of the platinum conductive layer 120 also helps to improve the stability and durability of the proton exchange membrane electrolysis water membrane electrode. Because platinum has excellent corrosion resistance and chemical stability, it not only maintains stable performance in the harsh working environment of the proton exchange membrane electrolysis water membrane electrode, but also protects the iridium catalyst layer 110 from electrolytes or other corrosive substances, helping to extend the service life of the anode composite catalyst layer 100. Furthermore, since the platinum conductive layer 120 can reduce contact resistance, it can solve the problem of excessive heat accumulation due to high contact resistance, thereby slowing down the thermal aging process of the proton exchange membrane electrolysis water membrane electrode.

[0029] In addition to reducing contact resistance, the platinum conductive layer 120 can also synergistically catalyze with the iridium catalyst layer 110, resulting in higher catalytic activity of the anode composite catalyst layer 100 compared to a single catalyst layer. Simultaneously, the platinum conductive layer 120 covering the iridium catalyst layer 110 further increases the number of active sites on the catalyst. These active sites can more effectively adsorb and convert reactants, thereby improving the catalytic reaction rate.

[0030] The particle size of the platinum nanoparticles in the platinum conductive layer 120 has a critical impact on the contact resistance and stability of the membrane electrode. If the particle size of the platinum nanoparticles is too large, it will lead to high contact resistance, hindering electron transport and thus reducing the performance of the proton exchange membrane electrolysis water electrode. Conversely, if the particle size of the platinum nanoparticles is too small, the specific surface area of ​​the particles will be high, resulting in high surface energy, making the nanoparticles prone to instability such as aggregation, sedimentation, or dissolution. The inventors of this application have discovered that when the particle size of the platinum nanoparticles is between 10 nm and 500 nm, the contact resistance and stability of the membrane electrode can be better balanced.

[0031] In some preferred embodiments, the platinum nanoparticles have a particle size of 90 nm to 120 nm. More preferably, the platinum nanoparticles have a particle size of 95 nm to 110 nm. Most preferably, the platinum nanoparticles have a particle size of 100 nm, which optimizes the contact resistance and stability of the membrane electrode.

[0032] The thickness of the platinum conductive layer 120 also affects the contact resistance and stability of the membrane electrode. As the thickness of the platinum conductive layer 120 increases, the path of the reactant gas from the gas diffusion layer to the catalyst surface is lengthened, thereby increasing mass transfer resistance. This leads to a slower diffusion rate of the reactant gas in the catalyst layer, affecting the rate and efficiency of the electrochemical reaction. Simultaneously, increasing the thickness of the platinum conductive layer 120 also increases contact resistance, reduces the battery's current density, and increases heat generation and accumulation, which is detrimental to the stability and high-voltage durability of the membrane electrode. Furthermore, if the platinum conductive layer 120 is too thick, it will affect the transport and distribution of moisture, potentially causing flooding or drying inside the membrane electrode, thus affecting battery performance and lifespan. In some preferred embodiments, the thickness of the platinum conductive layer is 1.5 μm to 1.8 μm. Preferably, the thickness of the platinum conductive layer is 0.50 μm to 0.70 μm.

[0033] The mass ratio of the platinum nanoparticles to the second ionomer affects the electrical conductivity and ionic conductivity. In some preferred embodiments, the mass ratio of the platinum nanoparticles to the second ionomer is 1:(0.35–0.9). Preferably, the mass ratio of the platinum nanoparticles to the second ionomer is 1:(0.35–0.5).

[0034] In some preferred embodiments, both the first ionomer and the second ionomer comprise a perfluorosulfonic acid resin. More preferably, the first ionomer and the second ionomer comprise one or more of Nafion D2020, Nafion NR50, Aquivion D79-25B, and HCD-1820, respectively. Even more preferably, the first ionomer and the second ionomer comprise Nafion D2020, respectively.

[0035] In some preferred embodiments, the iridium catalyst is IrO2 or IrRuO2. x1 IrO2 / TiO2, IrO2 / NbO x1 IrO2 / Ta2O5, IrO2 / WO x1 or IrO2 / Nb2O 5-x2 At least one of them, wherein x1 is 1 to 2 and x2 is 0 to 3.

[0036] This application also provides an anode composite catalyst layer slurry, comprising: an iridium catalyst layer slurry and a platinum conductive layer slurry, wherein the iridium catalyst layer slurry comprises: an iridium catalyst, a first ionomer and a first solvent; the platinum conductive layer slurry comprises platinum nanoparticles with a particle size of 10 nm to 500 nm, a second ionomer and a second solvent.

[0037] In some preferred embodiments, the mass ratio of the iridium catalyst, the first ionomer, and the first solvent is 1:(0.1-0.5):(5-50); the mass ratio of the platinum nanoparticles, the second ionomer, and the second solvent is 1:(0.35-0.9):(10-50).

[0038] In some preferred embodiments, the mass ratio of the platinum nanoparticles, the second ionomer, and the second solvent is 1:(0.35–0.9):(10–50). More preferably, this ratio is 1:(0.35–0.5):(10–50). Even more preferably, this ratio is 1:(0.35–0.5):10.

[0039] In some preferred embodiments, both the first ionomer and the second ionomer comprise a perfluorosulfonic acid resin. More preferably, the first ionomer and the second ionomer comprise one or more of Nafion D2020, Nafion NR50, Aquivion D79-25B, and HCD-1820. Even more preferably, the first ionomer and the second ionomer comprise Nafion D2020.

[0040] In some preferred embodiments, the iridium catalyst is IrO2 or IrRuO2. x1 IrO2 / TiO2, IrO2 / NbO x1 IrO2 / Ta2O5, IrO2 / WO x1 or IrO2 / Nb2O 5-x2 At least one of them, wherein x1 is 1 to 2 and x2 is 0 to 3.

[0041] In some preferred embodiments, the first solvent and the second solvent may be the same or different, and are selected from at least one of isopropanol, ethylene glycol, ethanol, n-propanol and water.

[0042] In some preferred embodiments, the solid content of the iridium catalyst layer slurry and the platinum conductive layer slurry is 6 wt% to 15 wt%.

[0043] This application also provides a method for preparing an anode composite catalyst layer, which is prepared using the above-mentioned anode composite catalyst layer slurry.

[0044] refer to Figure 2 In some embodiments, the preparation method of the anode composite catalyst layer includes the following steps:

[0045] S1: An iridium catalyst layer is formed on the surface of the proton exchange membrane of the membrane electrode using an iridium catalyst layer slurry and by coating or transfer method.

[0046] S2: A platinum conductive layer is formed on the surface of the iridium catalyst layer using a platinum conductive layer slurry and by coating or transfer methods.

[0047] refer to Figure 3 In other embodiments, the method for preparing the anode composite catalyst layer includes the following steps:

[0048] S10: A platinum conductive layer is formed on a transfer material using a platinum conductive layer paste and a coating or transfer method.

[0049] S20: An iridium catalyst layer is formed on the surface of the platinum conductive layer by using an iridium catalyst layer slurry and a coating method.

[0050] S30: The stacked structure of the platinum conductive layer and the iridium catalyst layer is transferred to the surface of the proton exchange membrane by a transfer method, and the transfer material is removed.

[0051] The steps for forming the film using the coating and transfer methods described above are all performed in a known manner.

[0052] This application also provides a membrane electrode, comprising a proton exchange membrane, a gas diffusion layer, and the aforementioned anode composite catalyst layer. The proton exchange membrane and the gas diffusion layer can employ any existing structure or material.

[0053] In some specific embodiments, the gas diffusion layer is a porous titanium diffusion layer.

[0054] In some specific embodiments, the proton exchange membrane is a perfluorosulfonic acid matrix membrane.

[0055] In some specific embodiments, the membrane electrode also includes other common membrane layer structures, such as a cathode catalyst layer adjacent to the proton exchange membrane.

[0056] The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Unless otherwise specified, the reagents and raw materials used can be purchased commercially. Experimental methods in the following embodiments that do not specify specific conditions are performed according to conventional methods and conditions, or according to the product instructions.

[0057] Iridium oxide particles were purchased from Heraeus, model H2EL-IrO; platinum nanoparticles were purchased from Johnson Matthey, model HISPEC1000; and Nafion D2020 was purchased from Chemours.

[0058] Example 1

[0059] This embodiment provides an anode composite catalyst layer and its preparation method. The anode composite catalyst layer includes an iridium catalyst layer and a platinum conductive layer. The iridium catalyst layer includes Nafion D2020 and iridium oxide particles dispersed in the Nafion D2020. The platinum conductive layer includes Nafion D2020 and platinum nanoparticles with a particle size of 100 nm dispersed in the Nafion D2020.

[0060] The method for preparing the anode composite catalyst layer includes the following steps:

[0061] (1) Mix 2g of 100nm platinum nanoparticles, 1g of Nafion D2020, 15g of isopropanol and 5g of deionized water evenly to obtain a platinum conductive layer slurry; mix 2g of iridium oxide particles, 1g of Nafion D2020, 5g of isopropanol and 5g of deionized water evenly to obtain an iridium catalyst layer slurry.

[0062] (2) The platinum conductive layer slurry is coated onto the PTFE substrate using a coating machine and dried to obtain a platinum conductive layer of 0.50μm to 0.70μm.

[0063] (3) The iridium catalyst layer slurry is coated onto the surface of the platinum conductive layer using a coating machine, and the iridium catalyst layer is obtained after drying. The thickness of the iridium catalyst layer is 5.0 μm to 5.3 μm.

[0064] Example 2

[0065] Compared with Example 1, the only difference between the anode composite catalyst layer and its preparation method in this example is that the particle size of the platinum nanoparticles is 10 nm.

[0066] Example 3

[0067] Compared with Example 1, the only difference between the anode composite catalyst layer and its preparation method in this example is that the particle size of the platinum nanoparticles is 50 nm.

[0068] Example 4

[0069] Compared with Example 1, the only difference between the anode composite catalyst layer and its preparation method in this example is that the particle size of the platinum nanoparticles is 200 nm.

[0070] Example 5

[0071] Compared with Example 1, the only difference between the anode composite catalyst layer and its preparation method in this example is that the particle size of the platinum nanoparticles is 500 nm.

[0072] Example 6

[0073] Compared with Example 1, the only difference between the anode composite catalyst layer and its preparation method in this example is that the thickness of the platinum conductive layer is 1 μm to 1.5 μm.

[0074] Comparative Example 1

[0075] Compared with Example 1, the only difference between the anode composite catalyst layer and its preparation method in this comparative example is that the particle size of the platinum nanoparticles is 5 nm.

[0076] Comparative Example 2

[0077] Compared with Example 1, the only difference between the anode composite catalyst layer and its preparation method in this comparative example is that the particle size of the platinum nanoparticles is 550 nm.

[0078] Comparative Example 3

[0079] Compared with Example 1, the only difference between the anode composite catalyst layer and its preparation method in this comparative example is that the mass ratio of platinum nanoparticles to Nafion D2020 is 1:0.33.

[0080] Comparative Example 4

[0081] Compared with Example 1, the only difference between the anode composite catalyst layer and its preparation method in this comparative example is that the mass ratio of platinum nanoparticles to Nafion D2020 is 1:1.

[0082] Comparative Example 5

[0083] Compared with Example 1, the only difference between the anode composite catalyst layer and its preparation method in this comparative example is that the thickness of the platinum conductive layer is 0.1 μm to 0.2 μm.

[0084] Comparative Example 6

[0085] This comparative example provides an anode catalyst layer and its preparation method, wherein the anode catalyst layer comprises Nafion D2020 and iridium oxide particles dispersed in the Nafion D2020.

[0086] The method for preparing the anode catalyst layer includes the following steps:

[0087] (1) Mix 2g of iridium oxide particles, 1g of Nafion D2020, 5g of isopropanol and 5g of deionized water evenly to obtain an anode catalyst layer slurry.

[0088] (2) The anode catalyst layer slurry is coated onto the surface of the perfluorosulfonic acid matrix membrane using a coating machine and dried to obtain the anode catalyst layer.

[0089] Performance characterization:

[0090] 1) The platinum conductive layer prepared in Example 1 was subjected to XRD testing using an X-ray diffractometer (Rigaku D / max-2500B2+ / PC). The scanning range was 10°–90°, and the angle increment was 0.03° / second. Please refer to the test results. Figure 4 .Depend on Figure 4 It can be seen that the crystal lattice of the sample corresponds to the standard card result of platinum, and the average particle size D of the platinum black particles is calculated to be 102 nm according to the following Sherrer equation.

[0091] D = Kλ / (βcosθ);

[0092] In the above formula, K is a constant; λ is the X-ray wavelength; β is the full width at half maximum (FWHM) of the diffraction peak; and θ is the diffraction angle. The value of the constant K in the above formula is related to the definition of β. When β is the FWHM, K is 0.89; when β is the integral width, K is 1.0.

[0093] 2) The platinum conductive layer prepared in Example 1 was subjected to TEM testing using a FEI TECNAI G2 F20 200KV field emission transmission electron microscope. The accelerating voltage was 200KV. Please refer to the test results. Figure 5 .exist Figure 5 In the diagram, the film layer in the red box is the platinum conductive layer, and the film layer between the red arrows is the iridium catalyst layer. The thickness of the platinum conductive layer is 0.50–0.70 μm, and the platinum nanoparticles are well dispersed without agglomeration.

[0094] Contact resistance test: The contact resistance test shall be performed in accordance with the standard GB / T 20042.6-2011.

[0095] Stability test:

[0096] The laminated structure of platinum conductive layer and iridium catalyst layer obtained in Examples 1-6 and Comparative Examples 1-6 was transferred to the surface of perfluorosulfonic acid matrix sub-membrane by transfer method, and the PTFE substrate was removed to obtain membrane electrode. After assembling the gas diffusion layer, the membrane electrode was tested.

[0097] After subjecting the obtained membrane electrode to 10,000 voltage cycles (1.45V (3 min) / 2.0V (3 min)), a current density of 2 A / cm² was measured. 2 The corresponding voltages and test results are shown in Table 1.

[0098] As shown in Table 1, although Comparative Examples 1 and 3 have low contact resistance comparable to the embodiments of this application, their voltage drop values ​​are much higher than those of the embodiments of this application. While Comparative Examples 2 and 4-6 have smaller voltage drop values, their contact resistance values ​​are higher. Therefore, compared to Comparative Examples 1-6, the membrane electrodes prepared using the anode composite catalyst layers of Examples 1-6 can combine lower contact resistance with excellent stability.

[0099] Table 1. Results of contact resistance and stability tests

[0100]

[0101] Membrane electrode performance testing

[0102] The membrane electrode prepared above was tested using an electrolysis water test bench. The specific test method is as follows:

[0103] 1) Prepare the test environment (water resistivity greater than 3MΩ / cm), ensure that the water and gas pipelines are set up correctly, and that the temperature control system can work normally;

[0104] 2) Assemble the water electrolysis fixture. Place the fixture on the table and assemble it from bottom to top in the following order: cathode end plate → gold-plated cathode plate → graphite plate → cathode gasket → carbon paper → membrane electrode → anode gasket → sintered titanium plate → anode flow channel plate → anode end plate. After all components are in place, tighten the screws with a torque wrench in a fixed sequence of 2→3→4→5 Nm per turn. Then install the water electrolysis fixture onto the test bench.

[0105] 3) Install the DC power supply load line and SENSE line, and turn on the flow meter so that the upper end of the float is close to the 100 mL / min mark. Press the heating button. Wait for the fixture temperature to rise to the set temperature of 80℃ before starting the test.

[0106] 4) Load the test program (increase by 0.2A / cm per stage) 2 Polarization curve tests were conducted by pausing for four minutes at each stage.

[0107] Table 2 shows the voltage values ​​at different current densities. The results show that, compared to Comparative Examples 2, 4, and 6, the membrane electrodes prepared with the anode composite catalyst layers of Examples 1-6 of this application exhibit lower voltage values ​​at the same current density when applied to water electrolysis. Therefore, the anode composite catalyst layers prepared in the examples of this application have better catalytic performance.

[0108] Table 2. Membrane electrode performance test results

[0109]

[0110] The above description of the embodiments is intended to enable those skilled in the art to understand and apply this application. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, this application is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. An anode composite catalyst layer, located between the proton exchange membrane and the gas diffusion layer of a membrane electrode, characterized in that, include: An iridium catalyst layer has opposing first and second surfaces, wherein the first surface faces the proton exchange membrane and the second surface faces the gas diffusion layer. The iridium catalyst layer comprises a first ionomer and an iridium catalyst dispersed in the first ionomer, wherein the iridium catalyst is IrO₂ or IrRuO₂. x1 IrO2 / TiO2, IrO2 / NbO x1 IrO2 / Ta2O5, IrO2 / WO x1 or IrO2 / Nb2O 5-x2 At least one of them, wherein x1 is 1 to 2 and x2 is 0 to 3; A platinum conductive layer has a third surface and a fourth surface opposite to each other, wherein the third surface is in contact with the second surface of the iridium catalyst layer and the fourth surface faces the gas diffusion layer, and the platinum conductive layer includes a second ionomer and platinum nanoparticles with a particle size of 10 nm to 500 nm dispersed in the second ionomer. The thickness of the platinum conductive layer is 0.3 μm to 1.5 μm; the mass ratio of the platinum nanoparticles to the second ionomer is 1:(0.35~0.9).

2. The anode composite catalyst layer according to claim 1, characterized in that, The platinum nanoparticles have a particle size of 90 nm to 120 nm.

3. The anode composite catalyst layer according to claim 1, characterized in that, The first ionomer and the second ionomer each comprise one or more of Nafion D2020, Nafion NR50, and Aquivion D79-25B.

4. A method for preparing an anode composite catalyst layer according to any one of claims 1 to 3, characterized in that, It is prepared using an anode composite catalyst layer slurry.

5. The method for preparing the anode composite catalyst layer according to claim 4, characterized in that, The anode composite catalyst layer slurry comprises: An iridium catalyst layer slurry, the iridium catalyst layer slurry comprising: an iridium catalyst, a first ionomer, and a first solvent; A platinum conductive layer slurry, comprising platinum nanoparticles with a particle size of 10 nm to 500 nm, a second ionomer, and a second solvent; wherein the mass ratio of the platinum nanoparticles to the second ionomer is 1:(0.35~0.9).

6. The method for preparing the anode composite catalyst layer according to claim 5, characterized in that, The mass ratio of the iridium catalyst, the first ionomer, and the first solvent is 1:(0.1~0.5):(5~50); the mass ratio of the platinum nanoparticles, the second ionomer, and the second solvent is 1:(0.35~0.9):(10~50).

7. The method for preparing the anode composite catalyst layer according to claim 5, characterized in that, The first ionomer and the second ionomer each comprise one or more of Nafion D2020, Nafion NR50, and Aquivion D79-25B; the iridium catalyst is IrO2 or IrRuO2. x IrO2 / TiO2, IrO2 / NbO x IrO2 / Ta2O5, IrO2 / WO x or IrO2 / Nb2O 5-x At least one of the following: the first solvent and the second solvent may be the same or different, and are selected from at least one of isopropanol, ethylene glycol, ethanol, n-propanol and water.

8. The method for preparing the anode composite catalyst layer according to any one of claims 5 to 7, characterized in that, The preparation method includes: An iridium catalyst layer is formed on the surface of the proton exchange membrane of a membrane electrode using an iridium catalyst layer slurry and by coating or transfer methods. A platinum conductive layer is formed on the surface of the iridium catalyst layer using a platinum conductive layer slurry and by coating or transfer methods. Alternatively, the preparation method includes: A platinum conductive layer paste is used to form a platinum conductive layer on a transfer material by coating or transfer printing. An iridium catalyst layer is formed on the surface of the platinum conductive layer by using an iridium catalyst layer slurry and a coating method. The laminated structure of the platinum conductive layer and the iridium catalyst layer is transferred to the surface of the proton exchange membrane by a transfer method, and then the transfer material is removed.

9. A membrane electrode, characterized in that, It includes a proton exchange membrane, a gas diffusion layer, and the anode composite catalyst layer as described in any one of claims 1 to 3.

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