A metal alloy catalyst for a pem electrolytic water system and a method for preparing the same

Abstract

This invention discloses a metal alloy catalyst for PEM water electrolysis systems and its preparation method. The method includes using a sol-gel method to uniformly stir a compound containing Ir and Ru elements, citric acid monohydrate, n-butanol, concentrated nitric acid, and a polyoxypropylene / polyoxyethylene copolymer solution to form a sol, followed by heating and drying to form a gel. This preparation method is simple and easy to implement, requires a low amount of the precious metal Ir, has a short reaction time, and can achieve uniform dispersion of iridium and ruthenium elements under normal pressure and relatively low temperature, making it easy to achieve mass production. The resulting metal alloy catalyst has advantages such as low cost, high catalytic activity, and good stability.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a metal alloy catalyst for PEM water electrolysis system and its preparation method. Background Technology

[0002] While the scale of renewable energy power generation is expanding year by year, the volatility and randomness of its power output pose significant challenges to the consumption of green electricity. PEM (Polymerized Electricity Extraction) water electrolysis for hydrogen production offers advantages in start-up / shutdown and adaptability, enabling the conversion of highly volatile renewable energy into high-quality hydrogen energy and achieving zero carbon emissions in the hydrogen production process. However, in actual operation of PEM electrolyzers, the four-electron transfer step on the anode oxygen evolution side is slow. Limited by the requirements of high overpotential and strongly acidic environmental conditions, Ir-based catalysts are currently the main type practically applicable to electrolyzers. However, iridium metal is expensive, scarce, and its activity needs further improvement.

[0003] Currently, many studies have improved the activity and stability of Ir-based catalysts by introducing non-Ir elements for alloying. For example, Ca ions have been introduced to prepare catalysts with IrO6 octahedral distortion (ACS Omega 2018, 3, 3, 2902–2908). Other examples include the preparation of perovskite and pyrochlore catalysts (Nat Commun 9, 5236 (2018); J. Am. Chem. Soc. 2020, 142, 17, 7883–7888), all of which have yielded excellent OER activity. Peter Strasser et al. also achieved good stability by preparing IrNb oxide catalysts.

[0004] All the studies on Ir-based catalysts mentioned above have effectively reduced the amount of the noble metal Ir used. However, most of these alloyed Ir-based catalysts are difficult to maintain long-term stability due to their unstable phase structures. Therefore, selecting elements that are relatively stable in acidic environments and designing stable bulk phase structures under electrochemical conditions is one of the effective pathways to obtain catalysts that balance both activity and stability. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a metal alloy catalyst for a PEM water electrolysis system.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0009] At room temperature, citric acid monohydrate is dissolved in deionized water to obtain the first solution;

[0010] Add chloroiridic acid and nitrosoruthenium nitrate to the first solution, and then sonicate to obtain the second solution;

[0011] Add n-butanol and concentrated nitric acid to the second solution, and then sonicate to obtain the third solution;

[0012] Add a polyoxypropylene-polyoxyethylene copolymer solution to the third solution, stir and mix evenly to obtain the first sol;

[0013] The first sol is dried to form the first gel;

[0014] The first gel was calcined in two stages and then cooled to room temperature to obtain the first solid particles.

[0015] The first solid particles were washed sequentially with H2SO4, then with deionized water, filtered, and dried to obtain the metal alloy catalyst for the PEM water electrolysis system.

[0016] In a preferred embodiment of the method for preparing the metal alloy catalyst for the PEM water electrolysis system described in this invention, the molar ratio of the metal elements in the chloroiridic acid and ruthenium nitrite is 1-9:0-1.

[0017] In a preferred embodiment of the method for preparing the metal alloy catalyst for the PEM water electrolysis system described in this invention, the molar ratio of the metal elements of the monohydrated citric acid, the chloroiridium acid, and the ruthenium nitrite is 4 to 0.5:1.

[0018] In a preferred embodiment of the preparation method of the metal alloy catalyst for the PEM water electrolysis system described in this invention, the amount of the polyoxypropylene-polyoxyethylene copolymer solution added is 0.5 to 2 mL for every 1 mmol of the metal elements of the chloroiridium acid and ruthenium nitrite.

[0019] In a preferred embodiment of the method for preparing the metal alloy catalyst for the PEM water electrolysis system described in this invention, the molar ratio of the metal elements of the n-butanol to the chloroiridic acid and ruthenium nitrite is 30-15:1.

[0020] In a preferred embodiment of the method for preparing the metal alloy catalyst for the PEM water electrolysis system described in this invention, the molar ratio of the concentrated nitric acid to the chloroiridium acid and ruthenium nitrite is 70-80:1.

[0021] In a preferred embodiment of the method for preparing the metal alloy catalyst for the PEM water electrolysis system described in this invention, the drying temperature of the first sol is 110-130°C and the drying time is 4-5 hours.

[0022] In a preferred embodiment of the method for preparing the metal alloy catalyst for the PEM water electrolysis system described in this invention, the temperature of the second stage of the programmed calcination is 300–550°C.

[0023] Another objective of this invention is to overcome the shortcomings of the prior art and provide a metal alloy catalyst for PEM water electrolysis systems.

[0024] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0025] The metal alloy catalyst is composed of Ir and Ru elements, specifically Ir. x Ru y , 0.5≤x≤1, 0≤y≤0.5; the metal alloy catalyst is a face-centered cubic iridium metal phase catalyst, with ruthenium element substituted for doping at iridium sites, and the particle size of the metal alloy catalyst is 5-6 nm.

[0026] Beneficial effects of this invention:

[0027] (1) The metal alloy catalyst for PEM water electrolysis system provided by the present invention and its preparation method can achieve uniform dispersion of iridium and ruthenium elements at normal pressure and low temperature, with short reaction time, simple and easy preparation method, and easy to achieve large-scale preparation and production.

[0028] (2) When the metallic phase iridium-ruthenium alloy catalyst prepared in this invention is used as the anode catalyst material for PEM water electrolysis, the amount of noble metal Ir can be as low as 0.3 mg·cm³. -2 It has the advantages of low cost, high catalytic activity and good stability. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0030] Figure 1 This is a flowchart illustrating the preparation process of the metal alloy catalyst in Example 1 of the present invention;

[0031] Figure 2 High-angle annular dark-field scanning transmission (HAADF-STEM) image analysis and X-ray energy dispersive spectroscopy (EDS) image analysis of the catalyst prepared in Example 1 of the present invention;

[0032] Figure 3 This is a particle size analysis diagram of the catalyst prepared in Example 1 of the present invention;

[0033] Figure 4 Example 1 of the present invention is performed in a PEMWE single electrolyzer at 2A cm⁻¹. -2 Stability test diagram of constant current;

[0034] Figure 5 Electrochemical polarization curves of the catalysts prepared in Examples 1-2 of this invention were tested in a three-electrode system.

[0035] Figure 6 The polarization curves of the catalysts prepared in Examples 1-2 of this invention in a PEMWE single electrolyzer are shown.

[0036] Figure 7 The XRD patterns are of the catalysts prepared in Examples 1-5 of this invention;

[0037] Figure 8 Electrochemical polarization curves of the catalysts prepared in comparative examples 1-3 of this invention were tested in a three-electrode system.

[0038] Figure 9 The XRD pattern of the catalyst prepared in Example 6 of this invention;

[0039] Figure 10 Electrochemical polarization curves of the catalysts prepared in Example 6 and Comparative Example 6 of this invention were tested in a three-electrode system.

[0040] Figure 11 The catalyst prepared in Example 7 of this invention was subjected to electrochemical polarization curve testing in a three-electrode system. Detailed Implementation

[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0042] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0043] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0044] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0045] The testing methods involved in this invention

[0046] Three-electrode testing method: The reference electrode was mercury / mercurous sulfate, and the counter electrode was a carbon rod. The working electrode was prepared by coating a catalytic ink onto a 3 mm diameter glassy carbon electrode. The ink formulation consisted of 5 mg of catalyst and 50 μL of Nafion solution dispersed in 450 μL of ethanol, and sonicated for at least 30 min to form a homogeneous ink. Then, 3.6 μL of the dispersion (containing 0.5 mg of catalyst) was drop-coated onto a clean glassy carbon electrode, resulting in a catalyst loading of 0.5 mg / cm³ on the electrode. -2 The electrolyte used was 1M H₂SO₄. The test temperature was 30℃. First, at 50mV s -1 Cyclic voltammetry (CV) scans were performed on the working electrode within a potential range of 0.3–1.5 V (vs. RHE) to activate it. Then, cyclic voltammetry was performed at 5 mV / s. -1 Linear sweep voltammetry (LSV) tests were performed at a sweep rate of 1.1-1.7V within a potential range of 1.1-1.7V.

[0047] Membrane electrode testing method: Membrane electrode assembly (MEA) was performed using the catalyst-coated membrane (CCM) method. Ir 0.7 Ru 0.3 Commercial Pt / C was used as the cathode catalyst, with Pt / C used as the anode catalyst. The temperature of the electrolysis unit was maintained at 80°C. Polarization curves were tested after electrochemical activation. The stability of the membrane electrode was measured at 2A cm⁻¹. -2 The electrolysis voltage of the electrolytic cell under the current density was characterized.

[0048] Example 1

[0049] This embodiment provides a method for preparing a metal alloy catalyst for a PEM water electrolysis system, specifically as follows:

[0050] (1) At room temperature, 0.4 mmol of citric acid monohydrate was dissolved in 1 mL of deionized water to obtain the first solution;

[0051] (2) Add chloroiridium acid containing 0.14 mmol of iridium and 0.06 mmol of ruthenium to the first solution, and sonicate for 20 min to obtain the second solution;

[0052] (3) Add 4.2 mmol n-butanol and 15.6 mmol concentrated nitric acid to the second solution, and sonicate for 20 min to obtain the third solution;

[0053] (4) Add 1 mL of polyoxypropylene-polyoxyethylene copolymer solution to the above third solution and stir for 2 h to obtain the first sol;

[0054] (5) The first sol was dried at 120°C for 4 hours to form the first gel;

[0055] (6) The first gel was placed in a tube furnace and calcined at 250°C for 2 hours in the first stage and at 350°C for 2 hours in the second stage. After cooling to room temperature, the first solid particles were obtained.

[0056] (7) The first solid particles were washed with 100 mL of 0.5 M H2SO4 for 5 h, then washed with deionized water, filtered, and dried in a 55 °C drying oven for 12 h to obtain Ir. 0.7 Ru 0.3 Metal phase catalyst.

[0057] The catalyst prepared in Example 1 was characterized by high-angle annular dark-field scanning transmission (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDS). The results are as follows: Figure 2 As shown.

[0058] The catalyst exhibits clear and uniform lattice fringes, and Ir and Ru elements are uniformly dispersed. Figure 3 Particle size analysis shows that the alloy catalyst particles are approximately 6 nm in size.

[0059] The stability test of the catalyst prepared in Example 1 under a constant current of 2A was performed as follows: Figure 4 As shown. From Figure 4 It is clear from the data that after 550 hours of operation, Ir 0.7 Ru 0.3 The catalyst exhibits a performance degradation rate of only 7.74 μV / h, indicating that it possesses excellent oxygen evolution stability.

[0060] Example 2

[0061] This embodiment provides a method for preparing a metal phase catalyst for a PEM water electrolysis system. The content of iridium in chloroiridic acid in step (2) of Example 1 is adjusted to 0.2 mmol, and ruthenium nitrite is not added. That is, the molar ratio of chloroiridic acid and ruthenium nitrite is 1:0. The rest of the preparation process is the same as in Example 1, and the Ir metal phase catalyst is prepared.

[0062] Electrochemical polarization curves of the catalysts prepared in Examples 1 and 2 were tested in a three-electrode system, and the results are as follows: Figure 5 As shown, the Ir prepared in Example 1 0.7 Ru 0.3 At 10mAcm -2 The overpotential at current density is only 228.7mV, which is much lower than the overpotential of Ir, which is 284.2mV.

[0063] The performance of PEMWE single cells assembled using the catalysts prepared in Examples 1 and 2 as anode catalysts was tested, and the results are as follows: Figure 6 As shown. According to Figure 6 It can be seen that the Ir prepared using the method in Example 1... 0.7 Ru 0.3 The catalyst exhibits high oxygen evolution reaction activity during PEM hydrolysis, 2 A·cm -2 The electrolysis voltage at the current density is only 1.75V, compared to an overpotential of 1.78V for the Ir catalyst.

[0064] Both the three-electrode and PEMWE single-cell electrochemical test results show that the catalyst forming the IrRu alloy has better performance than the single-metal Ir.

[0065] Example 3

[0066] This embodiment provides a method for preparing a metal alloy catalyst for a PEM water electrolysis system. The iridium content in chloroiridium acid in step (2) of Example 1 is adjusted to 0.16 mmol, and the ruthenium content in nitrosoruthenium nitrate is adjusted to 0.04 mmol, i.e., the molar ratio of chloroiridium acid to nitrosoruthenium nitrate is 4:1. The remaining preparation process is the same as in Example 1, and Ir is obtained. 0.8 Ru 0.2 Metal phase catalyst.

[0067] Example 4

[0068] This embodiment provides a method for preparing a metal alloy catalyst for a PEM water electrolysis system. The iridium content in chloroiridic acid in step (2) of Example 1 is adjusted to 0.12 mmol, and the ruthenium content in nitrosoruthenium nitrate is adjusted to 0.08 mmol, i.e., the molar ratio of chloroiridic acid to nitrosoruthenium nitrate is 1.5:1. The remaining preparation process is the same as in Example 1, and Ir is obtained. 0.6 Ru 0.4 Metal phase catalyst.

[0069] Example 5

[0070] This embodiment provides a method for preparing a metal alloy catalyst for a PEM water electrolysis system. The iridium content in chloroiridic acid in step (2) of Example 1 is adjusted to 0.1 mmol, and the ruthenium content in nitrosoruthenium nitrate is adjusted to 0.1 mmol, i.e., the molar ratio of the metal elements in chloroiridic acid and nitrosoruthenium nitrate is 1:1, thus preparing Ir... 0.5 Ru 0.5 Metal phase catalyst.

[0071] XRD analysis was performed on the catalysts prepared in Examples 1-5, and the results are as follows: Figure 7 As shown.

[0072] Depend on Figure 7 It can be seen that the characteristic peaks of the prepared Ir catalyst match the characteristic peaks of elemental Ir. The synthesized Ir... 0.8 Ru 0.2 Ir 0.7 Ru 0.3 Ir 0.6 Ru 0.4 Ir 0.5 Ru 0.5 The catalyst exhibits characteristic peaks similar to those of elemental Ir, with a slight shift towards the large Bragg angle, indicating that the synthesized Ir... 0.7 Ru 0.3 Ir 0.6 Ru 0.4 Ir 0.5 Ru 0.5 The catalyst is a similar metallic phase, with Ru element substituted and doped at Ir sites.

[0073] High-angle annular dark-field scanning transmission (HAADF-STEM) image analysis was performed on the catalysts prepared in Examples 2-5, and the results showed that... Figure 2 Similarly, this indicates that the morphology of the prepared catalysts is similar. X-ray energy dispersive spectroscopy (EDS) image analysis of the catalysts prepared in Examples 3-5 also yielded similar results. Figure 2 Similarly, it can be seen that Ir and Ru elements are evenly dispersed.

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 1 is that citric acid monohydrate is not added in step (1), while the rest of the preparation process is the same as in Example 1, and Ir is prepared. 0.7 Ru 0.3 catalyst.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that the polyoxypropylene-polyoxyethylene copolymer solution is not added in step (4), while the rest of the preparation process is the same as in Example 1, and Ir is obtained. 0.7 Ru 0.3 catalyst.

[0078] Comparative Example 3

[0079] The difference between this comparative example and Example 1 is that n-butanol is not added in step (3), while the rest of the preparation process is the same as in Example 1, and Ir is prepared. 0.7 Ru 0.3 catalyst.

[0080] Electrochemical polarization curves of the catalysts prepared in Comparative Examples 1-3 were tested in a three-electrode system, and the results are as follows: Figure 8 As shown, Ir prepared in Comparative Examples 1-3 0.7 Ru 0.3 At 10mAcm -2 The overpotentials at the current densities were all higher than the 228.7 mV in Example 1. This indicates that the absence of citric acid, polyoxypropylene-polyoxyethylene copolymer solution, and n-butanol would have a negative impact on electrochemical activity.

[0081] Example 6

[0082] This embodiment provides a method for preparing a metal alloy catalyst for a PEM water electrolysis system. The temperatures in the second stage of the calcination process in step (6) of Example 1 are adjusted to 300℃, 450℃, and 550℃, respectively. The remaining preparation processes are the same as in Example 1, and Ir is obtained. 0.7 Ru 0.3 Alloy catalyst.

[0083] Comparative Example 4

[0084] The difference between this comparative example and Example 1 is that the temperatures in the second stage of the calcination process in step (6) of Example 1 were adjusted to 750°C, 850°C, and 950°C, respectively. All other preparation processes were the same as in Example 1, and Ir was obtained. 0.7 Ru 0.3 Alloy catalyst.

[0085] The Ir prepared in Example 6 and Comparative Example 4 0.7 Ru0.3 The catalyst was subjected to XRD testing and electrochemical polarization curve testing in a three-electrode system. The results are as follows: Figures 9-10 As shown.

[0086] from Figure 9 As can be seen, when the second stage of calcination is at 300℃, the catalyst prepared has characteristic peaks similar to those of elemental Ir. At temperatures of 450℃ and 550℃, characteristic peaks similar to both elemental Ir and rutile IrO2 appear simultaneously. The catalyst obtained at 350℃ exhibits the best performance. The catalyst prepared in Comparative Example 4 only shows characteristic peaks similar to rutile IrO2, and its catalytic performance shows a decreasing trend. Figure 10 ).

[0087] Example 7

[0088] This embodiment provides a method for preparing a metal alloy catalyst for a PEM water electrolysis system. The amount of citric acid monohydrate in step (1) of Example 1 is adjusted to 0.1 mmol, 0.2 mmol, and 0.8 mmol, respectively, meaning the molar ratio of citric acid monohydrate to iridium chlorohydrate and ruthenium nitrite is adjusted to 0.5:1, 1:1, and 4:1. The remaining preparation process is the same as in Example 1, yielding Ir... 0.7 Ru 0.3 Alloy catalyst.

[0089] Electrochemical polarization curves were tested on the catalyst prepared in Example 7, and the results showed that it also exhibited good electrochemical activity. Figure 11 However, the concentration was slightly lower than that in Example 1, indicating that the catalyst exhibited the best electrochemical activity when the amount of citric acid monohydrate was 0.4 mmol, i.e., the molar ratio of citric acid monohydrate to chloroiridium acid and ruthenium nitrite was 2:1.

[0090] Example 8

[0091] This embodiment provides a method for preparing a metal alloy catalyst for a PEM water electrolysis system. The amount of polyoxypropylene-polyoxyethylene copolymer solution added in Example 1 was adjusted to 2 mL and 0.5 mL, respectively. All other preparation processes were the same as in Example 1, resulting in the Ir catalyst of this embodiment. 0.7 Ru 0.3 Alloy catalyst.

[0092] Electrochemical polarization curves were tested on the catalyst prepared in Example 8. The results showed that the catalyst prepared in Example 8 also had good electrochemical activity, but it was slightly lower than that in Example 1. This indicates that the catalyst prepared with the best electrochemical activity was when the amount of polyoxypropylene polyoxyethylene copolymer solution added was 1 mL.

[0093] In summary, this invention discloses a method for preparing a metal alloy catalyst for a PEM water electrolysis system. Compared with the prior art, it does not require a reducing atmosphere. In this invention, one end of the citric acid molecule is connected to the polyoxypropylene-polyoxyethylene copolymer solution, which is beneficial to the dispersion of metal elements. At the same time, during the calcination process, citric acid can also act as a reducing agent to reduce high-valence metal ions.

[0094] The preparation method of this invention employs a sol-gel method, in which a compound containing Ir and Ru elements, citric acid monohydrate, n-butanol, concentrated nitric acid, and a polyoxypropylene-polyoxyethylene copolymer solution are stirred until homogeneous to form a sol, which is then dried by heating to form a gel. This method is simple, easy to implement, requires a low amount of the precious metal Ir, has a short reaction time, and can achieve uniform dispersion of iridium and ruthenium elements under normal pressure and relatively low temperature, making it easy to achieve mass production. The resulting metal alloy catalyst has low cost, high catalytic activity, and good stability.

[0095] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a metal alloy catalyst for a PEM water electrolysis system, characterized in that: include, At room temperature, citric acid monohydrate is dissolved in deionized water to obtain the first solution; Add chloroiridic acid and nitrosoruthenium nitrate to the first solution, and then sonicate to obtain the second solution; Add n-butanol and concentrated nitric acid to the second solution, and then sonicate to obtain the third solution; Add a polyoxypropylene-polyoxyethylene copolymer solution to the third solution, stir and mix evenly to obtain the first sol; The first sol is dried to form the first gel; The first gel was subjected to a two-stage calcination process, and after cooling to room temperature, the first solid particles were obtained; wherein the temperature of the second stage of the calcination process was 300~350℃. The first solid particles were washed sequentially with H2SO4, then with deionized water, filtered, and dried to obtain the metal alloy catalyst for the PEM water electrolysis system.

2. The method for preparing the metal alloy catalyst for the PEM water electrolysis system as described in claim 1, characterized in that: The molar ratio of the metal elements in the chloroiridic acid and nitrosoruthenium nitrate is 1~9:0~1.

3. The method for preparing the metal alloy catalyst for the PEM water electrolysis system as described in claim 1, characterized in that: The molar ratio of the metal elements in the monohydrated citric acid to the chloroiridium acid and ruthenium nitrite is 4~0.5:

1.

4. The method for preparing the metal alloy catalyst for the PEM water electrolysis system as described in claim 1, characterized in that: For every 1 mmol of the metal elements of the chloroiridic acid and ruthenium nitrosonitrile added, the amount of the polyoxypropylene-polyoxyethylene copolymer solution added is 0.5~2 mL.

5. The method for preparing the metal alloy catalyst for the PEM water electrolysis system as described in claim 1, characterized in that: The molar ratio of the metal elements of n-butanol to chloroiridic acid and ruthenium nitrite is 30~15:

1.

6. The method for preparing the metal alloy catalyst for the PEM water electrolysis system as described in claim 1, characterized in that: The molar ratio of the concentrated nitric acid to the chloroiridic acid and ruthenium nitrite is 70-80:

1.

7. The method for preparing the metal alloy catalyst for the PEM water electrolysis system as described in claim 1, characterized in that: The drying temperature of the first sol is 110-130℃, and the drying time is 4-5 hours.

8. A metal alloy catalyst for PEM water electrolysis system prepared by any one of the preparation methods described in claims 1 to 7.

9. The metal alloy catalyst for PEM water electrolysis system as described in claim 8, characterized in that: The metal alloy catalyst is composed of Ir and Ru elements, specifically Ir. x Ru y , 0.5≤x≤1, 0≤y≤0.5; the metal alloy catalyst is a face-centered cubic iridium metal phase catalyst, with ruthenium element substituted for doping at iridium sites, and the particle size of the metal alloy catalyst is 5~6 nm.

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