Method for measuring adsorption capacity of ionic polymer on surface of noble metal in catalyst layer and application

Abstract

The invention provides a method for measuring the adsorption capacity of an ionic polymer on the surface of noble metal in a catalyst layer. The method comprises the following steps: quantitatively replacing protons in the ionic polymer with selected metal cations for marking; respectively preparing a catalyst layer containing a noble metal catalyst and a pseudo catalyst layer not containing noble metal by utilizing the marked ionic polymer; measuring the initial load of noble metals, ionic polymers and selected metal cations in the catalyst layer and the pseudo catalyst layer; respectively carrying out soaking and elution experiments on the catalyst layer and the pseudo catalyst layer, monitoring the residual load of selected metal cations, and carrying out normalization processing; respectively drawing normalized elution kinetic curves of the catalyst layer and the pseudo catalyst layer; and comparing and analyzing the two curves, and calculating the amount of the ionic polymer specifically adsorbed on the surface of the noble metal by using a linear extrapolation method. The method realizes lossless and specific quantitative characterization of the metal-ionic polymer interface adsorption capacity, and has the advantages of clear principle, low equipment threshold and accurate result.

Description

Technical Field

[0001] This invention belongs to the field of quantitative characterization technology of porous electrode interfaces, and specifically relates to a quantitative measurement method and application of the amount of ion polymer adsorption on the metal surface in a catalyst layer. Background Technology

[0002] In the catalyst layers of devices such as proton exchange membrane fuel cells and water electrolysis, ionic polymers (e.g., perfluorosulfonic acid ionic polymers) adsorbed on the catalyst metal surface (e.g., platinum) form a nanolayer. This interfacial structure directly dominates the electrochemical reactions, proton conduction, and gas transport processes, and is a key mesoscopic structure determining device performance and durability. Crucially, due to the strong and specific interactions between the ionic polymers and the noble metal catalyst, the adsorption state properties on the metal surface differ significantly from the bulk material properties. Therefore, accurately quantifying the amount of ionic polymers adsorbed on the noble metal surface is a core prerequisite for elucidating the structure-activity relationship of the catalyst layer and optimizing the electrode structure.

[0003] However, non-destructive and quantitative characterization of this key parameter remains a significant challenge. Existing technologies can be mainly divided into two categories, but both have important limitations:

[0004] 1. Offline, bulk-average characterization techniques: Represented by small-angle neutron scattering (SANS). For example, Harada et al. at Toyota's Central Research Laboratory used contrast-varying SANS to distinguish between "adsorbed" and "deposited" ionic polymers on carbon particles and inferred the thickness of the adsorbed layer (~51 Å). [1] However, this method relies on large-scale national neutron source facilities, which are scarce and extremely expensive. More importantly, its signal reflects the statistical average of the bulk structure of the material, making it difficult to specifically decouple and accurately quantify the adsorption amount in the local area of ​​the "metal surface".

[0005] 2. Tomographic microscopy: Represented by cryo-transmission electron microscopy (cryo-TEM). Girod et al. recently used deep learning-assisted cryo-TEM tomography to achieve, for the first time, three-dimensional nanoimaging of all components (carbon, platinum, and ionomers) of the catalyst layer. [2] This work reveals key information such as the morphology and coverage of ionomer networks, representing a significant breakthrough in the field. However, this method also suffers from insurmountable drawbacks: (a) Electron beam irradiation damage: Even under high vacuum freezing conditions (98 K), ionomer films still experience a 10-40% thickness loss, meaning the observation results are not entirely lossless; (b) Extremely complex sample preparation and imaging: Relying on ultrathin slicing, complex image acquisition, and time-consuming deep learning segmentation and reconstruction processes, it lacks the universality for high-throughput analysis.

[0006] In summary, neither statistical averaging scattering techniques nor high-resolution imaging techniques can achieve non-destructive and quantitative analysis of the adsorption amount of ionic polymers on noble metal surfaces. Therefore, developing a method capable of non-destructive, specific, and quantitative characterization of the adsorption amount of ionic polymers on noble metal surfaces has become an urgent technical problem to be solved in this field.

[0007] References:

[0008] [1] Harada M, Takata S, Iwase H, et al. Distinguishing adsorbed and deposited ionomers in the catalyst layer of polymer electrolyte fuel cells using contrast-variation small-angle neutron scattering[J]. ACS omega, 2021,6(23): 15257-15263.

[0009] [2] Girod R, Lazaridis T, Gasteiger HA, et al. Three-dimensionalnanoimaging of fuel cell catalyst layers[J]. Nature catalysis, 2023, 6(5):383-391. Summary of the Invention

[0010] This invention aims to address at least one of the technical problems existing in the background art, and provides a method for non-destructive and quantitative measurement of the adsorption amount of ion polymers on the surface of noble metals in a catalyst layer. This method, through chemical substitution labeling and elution kinetic differential analysis, has a clear principle and is simple to operate, providing a novel characterization tool for accurately elucidating the metal-ion polymer interface structure in the catalyst layer.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] The first aspect of this invention provides a method for measuring the amount of ion polymer adsorption on the surface of a noble metal in a catalyst layer, comprising:

[0013] The protons in the ionomer are quantitatively replaced with selected metal cations to obtain the labeled ionomer;

[0014] The labeled ionic polymer is mixed and dispersed with a noble metal catalyst and a corresponding non-noble metal support to obtain a catalyst layer slurry and a pseudo catalyst layer slurry. The catalyst layer and the pseudo catalyst layer are obtained using the catalyst layer slurry and the pseudo catalyst layer slurry, respectively.

[0015] The loading of noble metals, ionic polymers, and metal cations in the catalyst layer was determined; the loading of ionic polymers and metal cations in the pseudo-catalyst layer was also determined.

[0016] The catalyst layer and the pseudo-catalyst layer were respectively immersed in deionized water as samples;

[0017] During the soaking process, samples were taken out at set time intervals, dried, and the residual metal cation loading was measured. The residual metal cation loading of the catalyst layer and the pseudo-catalyst layer were normalized based on the noble metal loading and / or the ion polymer loading, respectively.

[0018] Based on the normalization results, normalized metal cation elution kinetic curves of the catalyst layer and the pseudo-catalyst layer were plotted respectively. By comparing and analyzing the two curves, the mass of the ionic polymer specifically adsorbed on the surface of the noble metal in the catalyst layer was calculated using linear extrapolation.

[0019] In some embodiments, the selected metal cation is an alkali metal ion or an alkaline earth metal ion.

[0020] In some embodiments, the selected metal cation is a potassium ion or a cesium ion.

[0021] In some embodiments, the noble metal catalyst comprises platinum group metals or alloys thereof.

[0022] In some embodiments, the thickness of the catalyst layer does not exceed 10 μm, and the loading of noble metals does not exceed [a certain value]. .

[0023] In some embodiments, the resistivity of the deionized water is greater than or equal to 18 MΩ·cm, and the soaking process is carried out under air-isolated conditions.

[0024] In some embodiments, the liquid height used for immersion satisfy: ,in Let be the diffusion coefficient of the metal cation in water. This refers to the soaking time.

[0025] In some embodiments, the step of calculating the mass of the ionic polymer specifically adsorbed on the surface of the noble metal by comparing and analyzing two curves and using linear extrapolation includes:

[0026] Extrapolating the segment exhibiting a slow, linear decrease in the normalized metal cation elution kinetics curve of the catalyst layer to a time when the immersion time is zero yields the intercept. The slope of the slowly linearly decreasing segment in the elution kinetics curve of the catalyst layer is the same as the slope of the normalized metal cation elution kinetics curve of the pseudo-catalyst layer; the initial normalized metal cation loading of the catalyst layer is denoted as... The mass percentage of the ionic polymer adsorbed on the surface of the noble metal is: The mass of the ionic polymer adsorbed on the surface of the noble metal is obtained based on the mass ratio and the loading of the ionic polymer.

[0027] In some embodiments, the loading of the noble metal and the metal cation is determined using X-ray fluorescence spectroscopy, inductively coupled plasma mass spectrometry, or atomic absorption spectroscopy, and the loading of the ion polymer is determined based on the mass ratio of the ion polymer to the noble metal and the measured loading of the noble metal.

[0028] The second aspect of the present invention provides the application of the measurement method described in any embodiment of the first aspect of the present invention in characterizing the performance of the catalyst layer of a proton exchange membrane fuel cell or a water electrolysis device.

[0029] The present invention has the following beneficial effects:

[0030] 1) Innovative principle, non-destructive quantification: By pre-labeling ionomers ( Replace with By utilizing the difference in adsorption strength between noble metals and inert supports, resulting in different elution kinetics, specific and non-destructive quantitative separation of polymers with strong adsorption ions at metal interfaces was achieved.

[0031] 2) Precise signal decoupling: By introducing a pseudo-catalytic layer with identical control and using normalization to eliminate background differences, the elution behavior of signals such as carbon support adsorption and free ion polymers is completely subtracted, so that the final measurement results purely reflect the contribution of the strong interaction between noble metals and ion polymers, thus solving the problem of fuzzy interface signals in traditional bulk characterization techniques.

[0032] 3) Low implementation threshold and high universality: It does not rely on expensive and scarce equipment such as large synchrotron radiation, neutron sources or cryo-electron microscopy. The core steps only involve conventional wet chemical operations and elemental analysis, which greatly reduces the cost and application threshold of this characterization technology and facilitates its widespread promotion.

[0033] 4) Clear guiding significance: The obtained "adsorption amount of ion polymer on noble metal surface" is a direct and quantitative interfacial structure parameter, which can establish its structure-activity relationship with the catalyst layer slurry formulation, preparation process and final electrochemical performance, providing key experimental basis for the rational design and precise optimization of high-performance electrodes. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the catalyst layer and its substrate provided in an embodiment of the present invention being immersed in deionized water;

[0035] Figure 2 These are the elution kinetics curves of labeled metal cations in the catalyst layer and pseudo-catalyst layer provided in the embodiments of the present invention;

[0036] Figure 3 These are the mass measurement results of ionic polymers adsorbed on platinum / non-platinum surfaces in different I / C catalyst layers provided in the embodiments of the present invention. Detailed Implementation

[0037] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by related similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0038] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0039] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this application.

[0040] The first aspect of this invention provides a method for measuring the amount of ion polymer adsorption on the surface of a noble metal in a catalyst layer, comprising the following steps:

[0041] Step S1. Ion polymer labeling: Labeling protons in the ion polymer Quantitative replacement with selected metal cations The labeled ionic polymer was obtained;

[0042] Step S2. Preparation of catalytic layer and pseudo-catalytic layer slurry: The labeled ionic polymer obtained in step S1 is mixed with a noble metal catalyst and a support without noble metal, as well as a dispersion solvent, and uniformly dispersed to prepare catalytic layer slurry and pseudo-catalytic layer slurry respectively; the two slurries are coated and dried to form catalytic layer and pseudo-catalytic layer with a set thickness.

[0043] Step S3. Initial loading calibration: Determine the loading of noble metals, ionomers, and metal cations in the prepared catalyst layer. The loading of ionomers and metal cations in the prepared pseudocatalytic layer were determined. Load capacity;

[0044] Step S4. Immersion-elution experiment: Immerse the substrate with the catalyst layer and the substrate with the pseudo-catalyst layer in deionized water respectively;

[0045] Step S5. Elution process monitoring and data normalization: During the soaking process, the sample is taken out at set time intervals, dried, and the residual metal cations are measured. Loading; and normalized the residual metal cation loading of the catalyst layer and the pseudo-catalyst layer based on the noble metal loading and / or ion polymer loading (the loading of both is kept constant in the determination process of this application);

[0046] Step S6. Adsorption capacity calculation: Based on the normalization results of step S5, normalized metal cation elution kinetic curves of the catalytic layer and the pseudo-catalytic layer are plotted respectively; by comparing and analyzing the two curves, the mass of the ionic polymer specifically adsorbed on the noble metal surface is calculated.

[0047] In some embodiments, in step S1, the metal cation used for replacement It cannot have specific interactions with noble metal catalysts; metal cations can be selected. The ion is an alkali metal (using any one or more of lithium, sodium, potassium, rubidium, and cesium) or an alkaline earth metal ion, preferably potassium ions. or cesium ions .

[0048] Further, in step S1, the replacement method is an ion exchange method, such as titration or purification after reacting the ion polymer with an excess of the corresponding metal salt.

[0049] In some embodiments, in step S2, the noble metal catalyst is nanoparticles containing platinum group metals or their alloys, supported on a carbon black, carbon nanotube, or graphene carrier. The noble metal loading is between 0.03 and 0.2 mg.

[0050] In some embodiments, in step S2, the thickness of the prepared catalyst layer should be less than 10 μm, and the loading of noble metal should be less than [missing information]. This ensures controlled diffusion in the acceptor phase during ion exchange. This application does not impose lower limits on the catalyst layer thickness or noble metal loading; these depend on the preparation capability and the instrument's measurement limit. The sample thickness remains unchanged throughout the entire measurement process.

[0051] In some embodiments, in steps S3 and S5, the noble metal and the metal cation The loading can be determined by X-ray fluorescence spectroscopy (XRF), inductively coupled plasma mass spectrometry (ICP-MS), or atomic absorption spectroscopy (AAS). Since the mass ratio of the noble metal to the ion polymer is known, the loading of the ion polymer can be directly calculated from the measured loading of the noble metal and the mass ratio of the noble metal to the ion polymer.

[0052] In some embodiments, in step S4, the resistivity of the deionized water used is not less than 18 MΩ·cm (considering that impurity cations in non-deionized water will interfere with the measurement results, deionized water is used in this application to ensure the accuracy of the measurement results). During soaking, the catalyst layer should be kept facing upwards, and air should be isolated to avoid errors introduced by carbon dioxide dissolution. The soaking process is static diffusion controlled, that is, no convective disturbances such as stirring are introduced.

[0053] Furthermore, in step S4, the height of the liquid used for soaking... The following conditions must be met: ,in Metal cation Diffusion coefficient in water, This refers to the soaking time.

[0054] In some embodiments, the time interval set in step S5 includes several minutes to tens of hours after the start of immersion, such as 5, 10, ..., 60 minutes, 2, 3, 4, ..., 24 hours. The experiment is terminated when the residual loading approaches the detection limit (i.e., the residual metal cation signal intensity approaches 0). After the sample is removed, the surface moisture should be dried immediately with a gentle inert airflow and dried at a temperature below 100°C (preferably 60-90°C). Then, the residual metal cation loading in the dried sample is measured by XRF, and the measurement results are recorded. Then, the measured sample is put back into the ionized water for immersion at the set time interval. That is, step S5 is continuously performed according to the process of immersion-removal-measurement-re-immersion, and the time interval between two adjacent immersions does not exceed the preset time until the experimental termination condition is reached.

[0055] In some embodiments, step S6 is based on the following principle: the elution kinetic curve of the catalyst layer exhibits two stages: an initial rapid decrease and a later linear slow decrease; the elution kinetic curve of the pseudo-catalyst layer only exhibits a linear slow decrease stage, and its slope is the same as the later slope of the catalyst layer curve, denoted as . Therefore, the linear segment in the later stage of the catalyst layer elution kinetic curve is extended in reverse to the point where the immersion time is zero. (axis), to obtain the intercept The mass percentage of ionic polymers adsorbed on the surface of noble metals is then... ,in This represents the initial normalized metal cation loading of the catalyst layer.

[0056] The application of the above-described measurement method provided in the second aspect of the present invention in characterizing the catalytic layer performance of a proton exchange membrane fuel cell or a water electrolysis device.

[0057] The following describes specific embodiments of the present invention in detail.

[0058] Example 1: Measurement of the adsorption amount of perfluorosulfonic acid ion polymer on the platinum surface in the Pt / C catalyst layer of a proton exchange membrane fuel cell

[0059] This embodiment details the use of potassium ions. The specific process for measuring the adsorption amount of perfluorosulfonic acid ion polymers on the surface of commercial Pt / C catalysts as labeled cations.

[0060] 1. Materials and Instruments

[0061] 1) Ionic polymer: Perfluorosulfonic acid resin solution (Aquivion D79, EW=790, aqueous solution);

[0062] Catalyst: Platinum-carbon catalyst (Pt / C, TEC10V50E, Tanaka Kikinzoku Kogyo KK, platinum mass fraction 50%).

[0063] 2) Control carrier: Vulcan XC-72R toner;

[0064] 3) Titration reagent: Potassium hydroxide (KOH, analytical grade);

[0065] 4) Substrate material: 50 μm thick polytetrafluoroethylene film;

[0066] 5) Equipment: Homogenizer (IKA high-speed homogenizer), coating machine (adjustable wet film thickness, Kejing MSK-AFA-SC200), X-ray fluorescence spectrometer (HORIBA, MESA-50), constant temperature water bath, incubator, vacuum drying oven.

[0067] 2. Experimental Procedure

[0068] Step S1. Ion polymer labeling (preparation) Type perfluorosulfonic acid resin):

[0069] Take 10 g of perfluorosulfonic acid resin solution and add 0.1 M of [agent name missing] dropwise through a burette. The solution was stirred thoroughly, and the pH was monitored in real time with a pH meter until the titration endpoint (pH≈7).

[0070] Step S2. Preparation of the catalyst layer and pseudo-catalyst layer:

[0071] The slurry composition of the catalyst layer (platinum-carbon catalyst) and the pseudo-catalyst layer (carbon powder) is as follows: the mass ratio of solid ionic polymer to carbon I / C = 0.3, the solid mass fraction of the slurry is 20%, and the slurry solvent composition is water:ethanol = 1.3; in addition to water and ethanol, slurry solvents composed of water and other organic solutions can also be used.

[0072] The slurry was homogenized at 10 rpm for 40 minutes using a homogenizer, with the ambient temperature controlled by a temperature chamber. ;

[0073] Using a coating machine, the two slurries were respectively coated onto a clean polytetrafluoroethylene film, with the blade gap set to 20-30 μm (corresponding to a coating thickness of 4-7 μm). After the coated wet film was fully dried at room temperature, it was transferred to an 80°C drying oven and dried horizontally for 2 hours to obtain the catalytic layer and the pseudo-catalytic layer.

[0074] Step S3. Initial load calibration:

[0075] The signal intensity of each substance was measured using X-ray fluorescence spectrometry (signal intensity is proportional to the substance loading). The target platinum signal intensity in the catalyst layer was 54000 cps / mA (corresponding to...). The loading capacity must be within 10% to ensure test repeatability. The target sulfur signal intensity (reaction perfluorosulfonic acid loading) of the pseudo-catalyst layer is I / C×3050 cps / mA. The error requirement is <10%. If the sample signal intensity deviates from the target by more than the error requirement, return to step S2 to adjust the doctor blade gap and recoat until the requirement is met.

[0076] For samples that meet the requirements, to eliminate minor differences in absolute loading between samples, the signal intensity ratios of potassium to platinum and potassium to sulfur were measured and calculated, and used as initial values ​​for the normalized labeled metal cation signal intensity (loading) of the catalytic layer and pseudo-catalytic layer, respectively. .

[0077] Step S4. Immersion-elution experiment:

[0078] The experimental setup diagram for this step is shown below. Figure 1 As shown. The cut catalyst layer and pseudo-catalyst layer samples (2 cm × 2 cm) were separately immersed in sealed glass containers with a volume of 100 mL, ensuring that the catalyst layer and pseudo-catalyst layer were horizontally facing upwards and the substrate facing downwards. The sealed glass containers were pre-filled with deionized water with a resistivity of 18.2 MΩ·cm, and the liquid level h was approximately 10 cm. The sample was placed in a constant-temperature water bath and the container was quickly sealed to isolate it from air. The entire immersion process was carried out without any stirring or disturbance to ensure static diffusion control.

[0079] Diffusion condition verification: Diffusion coefficient of potassium ions in water at 25°C Approximately Preset maximum single soaking time. = 3 hours (10800 seconds). Calculated... Actual liquid height It is 10 cm, which satisfies the requirement. The conditions ensure that interfacial mass transfer is controlled by bulk diffusion.

[0080] Step S5. Elution process monitoring and data normalization:

[0081] At 5, 10, 15, 20, 25, 30, 40, 60, 90, 150, 210, ..., 1530 minutes after the start of immersion, one sample was removed from each of the parallel experimental groups. Immediately after removal, the sample surface was purged with a gentle stream of high-purity nitrogen for 10 seconds to remove any adhering water film. The samples were then dried in a vacuum drying oven at 80°C for 15 minutes. The residual potassium signal intensity was measured using XRF and normalized according to the processing method in step S3 to obtain the y-axis data. Furthermore, in this embodiment, the intensity of sulfur (corresponding to the sulfonic acid group of the ionomer) was also monitored simultaneously using XRF measurement, and its intensity remained within the range of 1750 ± 30 cps / mA, indicating that this gentle method did not damage the ionomer.

[0082] 3. Results Analysis

[0083] Step S6. Quantitative calculation of the adsorption capacity of ion polymers on the surface of noble metals:

[0084] Based on the normalized data obtained in step S5, normalized potassium ion elution kinetic curves for the catalyst layer and the pseudo-catalyst layer with I / C = 0.3 were plotted, as follows: Figure 2 As shown. Wherein:

[0085] Pseudo-catalytic layer curve: From the initial moment, the normalized potassium ion signal intensity decreases slowly and linearly with time, and its slope is denoted as k.

[0086] Catalytic layer curve: It exhibits a clear two-segment characteristic. The normalized potassium ion signal intensity decreases rapidly in the initial stage of immersion; then the curve turns into a linear slow decrease, and its slope is consistent with the slope k of the pseudo-catalytic layer curve within the error range.

[0087] According to the quantitative calculation method of the present invention, the linear segment in the later stage of the catalyst layer curve is extended in reverse to the zero point of immersion time (y-axis) to obtain the intercept. = 0.357 (dimensionless). The initial normalized potassium ion loading of this catalyst layer is = 1.0 (By definition, the residual K⁺ loading at the initial moment is equal to the initial ionomer loading, and the ratio is 1).

[0088] The mass ratio of perfluorosulfonic acid adsorbed on the platinum surface is:

[0089]

[0090] The known loading of ionomers in this catalyst layer sample is 0.015 mg / cm³. 2 The mass of ion polymer adsorbed on the platinum surface is 0.0097 mg / cm³. 2 .

[0091] To further demonstrate the application potential of this method, this invention compared three Pt / C catalyst layers with different I / C ratios (0.3, 0.6, 1.0) and measured the perfluorosulfonic acid adsorption amount on their platinum surfaces using the same method. The results are as follows: Figure 3 As shown, with the increase of total ionic polymer content, the adsorption amount of perfluorosulfonic acid on the platinum surface remains basically unchanged, while the content of other perfluorosulfonic acids increases linearly. This indicates that the strong interaction between perfluorosulfonic acid and platinum leads to its preferential adsorption on the platinum surface, and for the material system of this embodiment, saturation adsorption is already achieved at I / C = 0.2.

[0092] In summary, this embodiment details a non-destructive, well-defined, and reliable method for measuring the adsorption capacity of ionic polymers on noble metal surfaces. Through rigorous control experiments and diffusion-controlled immersion conditions, this method effectively decouples interface-specific signals, providing a powerful characterization tool for research and development in related fields.

[0093] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

Claims

1. A method for measuring the amount of ion polymer adsorption on the surface of noble metals in a catalyst layer, characterized in that, include: The protons in the ionomer are quantitatively replaced with selected metal cations to obtain the labeled ionomer; The labeled ionic polymer is mixed and dispersed with a noble metal catalyst and a corresponding non-noble metal support to obtain a catalyst layer slurry and a pseudo catalyst layer slurry. The catalyst layer and the pseudo catalyst layer are obtained using the catalyst layer slurry and the pseudo catalyst layer slurry, respectively. The loading of noble metals, ionic polymers and metal cations in the catalyst layer was determined; The loading of ionic polymers and metal cations in the pseudo-catalytic layer was determined; The catalyst layer and the pseudo-catalyst layer were respectively immersed in deionized water as samples; During the soaking process, samples were taken out at set time intervals, dried, and the residual metal cation loading was measured. The residual metal cation loading of the catalyst layer and the pseudo-catalyst layer were normalized based on the noble metal loading and / or the ion polymer loading, respectively. Based on the normalization results, normalized metal cation elution kinetic curves of the catalyst layer and the pseudo-catalyst layer were plotted respectively. By comparing and analyzing the two curves, the mass of the ionic polymer specifically adsorbed on the surface of the noble metal in the catalyst layer was calculated using linear extrapolation.

2. The measurement method according to claim 1, characterized in that, The selected metal cation is an alkali metal ion or an alkaline earth metal ion.

3. The measurement method according to claim 1, characterized in that, The selected metal cation is either potassium ion or cesium ion.

4. The measurement method according to claim 1, characterized in that, The noble metal catalyst comprises platinum group metals or their alloys.

5. The measurement method according to claim 1, characterized in that, The thickness of the catalyst layer does not exceed 10 μm, and the loading of noble metals does not exceed [a certain value]. .

6. The measurement method according to claim 1, characterized in that, The resistivity of the deionized water is greater than or equal to 18 MΩ·cm, and the soaking process is carried out under air-isolated conditions.

7. The measurement method according to claim 1 or 6, characterized in that, The height of the liquid used for soaking satisfy: ,in Let be the diffusion coefficient of the metal cation in water. This refers to the soaking time.

8. The measurement method according to claim 1, characterized in that, The method involves comparing and analyzing two curves, and using linear extrapolation to calculate the mass of the ionic polymer specifically adsorbed on the surface of the noble metal, including: Extrapolating the segment exhibiting a slow, linear decrease in the normalized metal cation elution kinetics curve of the catalyst layer to a time when the immersion time is zero yields the intercept. The slope of the slowly linearly decreasing segment in the elution kinetics curve of the catalyst layer is the same as the slope of the normalized metal cation elution kinetics curve of the pseudo-catalyst layer; the initial normalized metal cation loading of the catalyst layer is denoted as... The mass percentage of the ionic polymer adsorbed on the surface of the noble metal is: The mass of the ionic polymer adsorbed on the surface of the noble metal is obtained based on the mass ratio and the loading of the ionic polymer.

9. The measurement method according to claim 1, characterized in that, The loading of the noble metal and the metal cations was determined using X-ray fluorescence spectroscopy, inductively coupled plasma mass spectrometry, or atomic absorption spectroscopy. The loading of the ion polymer was determined based on the mass ratio of the ion polymer to the noble metal and the measured loading of the noble metal.

10. The application of the measurement method according to any one of claims 1 to 9 in characterizing the performance of the catalyst layer of a proton exchange membrane fuel cell or a water electrolysis device.

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