Method for determining metal content in PEM electrocatalyst

Abstract

The invention provides a method for measuring the content of metal in a PEM electrocatalyst, which comprises the following steps: S1, drying the electrocatalyst, then mixing the electrocatalyst with alumina powder, and carrying out ball milling to obtain mixed powder; s2, pressing the mixed powder into a to-be-detected sample through a tablet press; s3, respectively preparing standard samples of Pt, Ir, Ru and Ta with different concentrations, and respectively testing the ratio of the fluorescence intensity to the background intensity of the standard samples of Pt, Ir, Ru and Ta with different concentrations by using an X-ray fluorescence spectrophotometer, so as to obtain a standard curve between the ratio to the background intensity and the concentration of Pt, Ir, Ru and Ta; and S4, testing the ratio of the fluorescence intensity to the background intensity of the to-be-tested sample through the X-ray fluorescence spectrometer, and determining the Pt, Ir, Ru and Ta concentrations of the to-be-tested sample according to the standard curve. According to the method, the adding standard recovery rate is greater than 90%, the relative standard deviation is less than 1.0%, and the method is not only suitable for a carbon-based catalyst, but also suitable for a titanium-based catalyst and other electrocatalysts containing auxiliaries.

Description

Technical Field

[0001] The invention relates to the technical field of metal analysis, in particular to a method for determining the metal content in a PEM electrocatalyst. Background Art

[0002] Proton exchange membrane (PEM) electrocatalyst is one of the key components in proton exchange membrane fuel cells (PEMFC) and PEM electrolyzers. Its design and preparation are crucial to improving electrochemical performance. The catalyst coating in MEA (membrane electrode assembly) usually contains precious metal catalysts (such as Pt / C, Ir / C, Ir / TiO2, Ta / TiO2, etc.), deionized water, organic solvents (such as methanol) and polymer solution adhesives. Accurately determining the content of precious metals (such as platinum Pt, iridium Ir, ruthenium Ru, tantalum Ta) in the catalyst slurry is very important to ensure the performance and cost control of fuel cells.

[0003] At present, there are methods for detecting the precious metal content in ceramic catalysts. These methods usually use inductively coupled plasma optical emission spectroscopy (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS) for detection, and there are also cases of using X-ray fluorescence spectrometer (XRF) for detection. However, there are few studies on detection methods for MEA catalysts.

[0004] The national standard GB / T 20042.4-2009 provides two methods for detecting the precious metal content in PEM electrocatalysts: thermal analysis and ashing-acid dissolution-ICP method; however, in the actual production process, these two methods have some problems, such as: the thermal analysis method takes too little sample, resulting in large errors, and is only applicable to carbon-based catalysts such as Pt / C and Ir / C. It cannot effectively detect titanium-based catalysts such as Ir / TiO2 and Ta / TiO2, nor can it detect electrocatalysts with additives such as Cu, Ni, and Mn. The ashing-acid dissolution-ICP method is not suitable for catalysts containing Ir (such as Ir / C and Ir / TiO2) because Ir is difficult to dissolve in acid. Both methods are time-consuming, requiring more than 4 hours, and on the continuous production line of PEM electrocatalyst slurry, long-term chemical testing will affect the production rhythm.

[0005] Therefore, a fast and accurate detection method is needed to meet the needs of continuous production processes. X-ray fluorescence spectrometry is an ideal solution because of its fast, accurate and easy operation. XRF can complete the test in a few minutes, including sample pretreatment time, the whole process does not exceed 1 hour, which is very suitable for quality control on the production line. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for determining the metal content in a PEM electrocatalyst, which can quickly and accurately detect the precious metal content and is suitable for quality control on a production line.

[0007] The technical solution adopted by the present invention is:

[0008] A method for determining the metal content in a PEM electrocatalyst, comprising the following steps:

[0009] Step S1. drying the electrocatalyst, then mixing the dried electrocatalyst with alumina powder, and ball milling to obtain a mixed powder;

[0010] Step S2. Pressing the mixed powder into a sample to be tested by a tablet press;

[0011] Step S3. Prepare standard samples of different concentrations of Pt, Ir, Ru, and Ta respectively, and use an X-ray fluorescence spectrometer to test the ratio of the fluorescence intensity to the background intensity of the standard samples of different concentrations of Pt, Ir, Ru, and Ta, so as to obtain a standard curve between the ratio of the fluorescence intensity to the background intensity and the concentrations of Pt, Ir, Ru, and Ta;

[0012] Step S4. Test the ratio of the fluorescence intensity of the sample to be tested to the background intensity by an X-ray fluorescence spectrometer, and determine the Pt, Ir, Ru, and Ta concentrations of the sample to be tested based on the standard curve between the ratio of the fluorescence intensity to the background intensity in step S3 and the concentrations of Pt, Ir, Ru, and Ta.

[0013] Preferably, in the method for determining the metal content in a PEM electrocatalyst, the drying temperature in step S1 is 100° C.-160° C., and the drying time is 1-3 h.

[0014] Preferably, in the method for determining the metal content in a PEM electrocatalyst, the mass ratio of the electrocatalyst to the alumina powder in step S1 is 0.05-0.20:3-7.

[0015] Preferably, in the method for determining the metal content in a PEM electrocatalyst, the number of ball milling in step S1 is 1-3 times, the time of each ball milling is 30 seconds to 120 seconds, and the next ball milling is performed after each ball milling with an interval of 1-2 minutes.

[0016] Preferably, in the method for determining the metal content in a PEM electrocatalyst, the tablet press pressure in step S2 is 20-60 MPa, and the pressing time is 5-30 seconds.

[0017] Preferably, the method for determining the metal content in the PEM electrocatalyst, wherein: the preparation of standard samples of different concentrations of Pt, Ir, Ru, and Ta in step S3 specifically includes: mixing a standard solution containing known concentrations of Pt, Ir, Ru, and Ta with carbon powder, and then drying it in an oven at 100°C-160°C to obtain a standard sample, wherein the content of Pt, Ir, Ru, and Ta in the standard sample increases gradually.

[0018] Preferably, the method for determining the metal content in the PEM electrocatalyst is as follows: in step S3, the parameters of the X-ray fluorescence spectrometer when testing Pt are: using a LiF200 spectroscopic crystal, the voltage is 30-60 kV, the current is 50-80 mA, the counting time is 45s-120s, and the 2θ is 38.062°; the parameters when testing Ir are: using a LiF200 spectroscopic crystal, the voltage is 30-60 kV, the current is 50-80 mA, the counting time is 45s-120s, and the 2θ is 39.216°.

[0019] Preferably, the method for determining the metal content in the PEM electrocatalyst is as follows: in step S3, the parameters of the X-ray fluorescence spectrometer when testing Ru are: using LiF220 spectroscopic crystal, voltage 30-60kV, current 50-80mA, counting time 45s-120s, and 2θ is 26.123°; the parameters when testing Ta are: using LiF200 spectroscopic crystal, voltage 30-60kV, current 50-80mA, counting time 90s, and 2θ is 44.416°.

[0020] Preferably, the method for determining the metal content in a PEM electrocatalyst, wherein: the method for determining the metal content in a PEM electrocatalyst is suitable for detecting samples in which the precious metal content in the PEM electrocatalyst is 10%-90% of the dry powder mass.

[0021] Preferably, the method for determining the metal content in the PEM electrocatalyst, wherein: in step S3, the standard curve between the fluorescence intensity and the concentration of Pt, Ir, Ru, and Ta is obtained by: selecting the analysis elements Pt, Ir, Ru, and Ta respectively, then determining the curve type as a linear curve, and performing linear fitting. During the linear fitting process, the difference is controlled to be less than 1% of the sample content, the linear regression coefficient is greater than 0.999, and points with large errors are removed during the fitting process, and the linear regression coefficient is increased to a value greater than 0.9999; in order to improve the accuracy of the test results near a certain point, the weight of the point can be changed, and when the linear range is large, the curve segmentation can be selected to improve the accuracy of the test results; the linear regression coefficient of the standard curve needs to be greater than 0.999, and if it is less than 0.999, the standard sample needs to be remade or the test conditions need to be changed to re-establish the method.

[0022] Advantages of the present invention:

[0023] (1) The method of the present invention for determining the metal content in a PEM electrocatalyst has a short detection time, and sample preparation and testing can be completed within 1 hour; multiple elements can be detected simultaneously without interference from other elements; no acid dissolution or alkali fusion is required, and the operation is safe and pollution-free; there will be no detection deviation due to incomplete dissolution of the precious metals due to their stability. Iridium oxide is very stable and cannot be completely dissolved by acid or alkali. Ruthenium trichloride is very volatile, resulting in loss during the sample preparation process, affecting the test results.

[0024] (2) The method of the present invention for determining the metal content in PEM electrocatalysts is that the calcined α-alumina has extremely low water absorption and is relatively stable and can be stored for a long time. Since the precious metal content in MEA electrocatalysts generally exceeds 40%, and some can even reach 90%, direct XRF detection will result in excessive intensity. In addition, since the concentration span of MEA electrocatalysts is extremely large, and some contents are less than 1%, by controlling the added alumina content, the precious metal concentration of the sample to be tested can be controlled within a relatively narrow range, which is more suitable for the characteristics of XRF equipment and more accurate detection.

[0025] (3) The method of the present invention for determining the metal content in a PEM electrocatalyst has a spike recovery rate greater than 90% and a relative standard deviation (RSD) less than 1.0%. The method is applicable not only to carbon-based catalysts but also to titanium-based catalysts and other electrocatalysts containing additives.

[0026] (4) The method for determining the metal content in PEM electrocatalysts of the present invention establishes an accurate and reliable XRF detection method through specific sample pretreatment steps and combined with self-made standard samples, which specifically includes sample drying, sample grinding, mixing, tableting and other pretreatment steps, as well as rapid quantitative analysis of Pt, Ir, Ru, and Ta elements by XRF. This method overcomes the limitations of thermal analysis and ashing-acid dissolution-ICP methods in the prior art, such as small sampling volume and long detection time, and can be applied to various types of PEM electrocatalysts, including carbon-based and titanium-based catalysts. By comparing with the national standard GB / T20042.4-2009, the method of the present invention has high accuracy and stability, meets the ±5% deviation requirement, is suitable for the precise determination of precious metal elements in electrocatalysts, and can accurately detect the content of platinum, iridium, ruthenium, and tantalum in electrocatalysts. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments.

[0028] Example 1

[0029] A method for determining the metal content in a PEM electrocatalyst comprises the following steps:

[0030] Step S1. Take a 20mL ceramic crucible, dry it in an oven at 105°C to constant weight, put it in a drying oven and cool it to room temperature, weigh a certain amount of 1001# electrocatalyst, and put it in the ceramic crucible; put the ceramic crucible in a 105°C oven and dry it for 2h, take it out and put it in a drying oven to cool to room temperature, and calculate the moisture content ω of the electrocatalyst; take two grinding boxes dedicated to vibration ball mills, weigh 5.000g of alumina, weigh 0.0678g of the dried 1001# electrocatalyst, record the weighed weight m, mix the electrocatalyst and alumina in the grinding box, add steel balls, grind the sample 3 times with a vibration ball mill, each time for 1 minute, with a 2-minute interval in between, take out the ground sample, and bag it in a ziplock bag to obtain a mixed powder;

[0031] Step S2. Use an electronic balance to accurately weigh 3 g of the mixed powder, press the tablet with a plastic ring of a tablet press, set the pressure to 20 MPa, and continue for 15 seconds. After the pressing is completed, remove the sample to obtain the sample to be tested and wait for further testing;

[0032] Step S3. Prepare standard samples of different concentrations of Pt, Ir, Ru, and Ta respectively, and use an X-ray fluorescence spectrometer to test the fluorescence intensity of the standard samples of different concentrations of Pt, Ir, Ru, and Ta respectively, so as to obtain the ratio of fluorescence intensity to background intensity and the standard curve between the concentrations of Pt, Ir, Ru, and Ta;

[0033] Step S3 is specifically as follows:

[0034] Step S31. Mix the standard solution containing known concentrations of Pt, Ir, Ru, and Ta with the carbon powder, then stir the sample evenly with a stirrer for 4 hours, and then dry it in an oven at 120°C to obtain a standard electrocatalyst, the concentration of precious metals of which is shown in Table 1

[0035] Table 1 Concentration of noble metals in standard electrocatalysts

[0036]

[0037] Then, a certain weight of standard electrocatalysts were taken and mixed with alumina in a certain proportion to prepare four sets of standard samples of Pt, Ir, Ru, and Ta, totaling 24 standard samples, whose mixing proportions and contents are shown in Table 2.

[0038] Table 2 Precious metal concentrations of standard samples

[0039]

[0040]

[0041] Step S32. Set the test conditions of the X-ray fluorescence spectrometer. The analysis conditions are as follows: Pt uses a LiF200 spectroscopic crystal, a voltage of 60 kV, a current of 50 mA, a counting time of 60 s, and a 2θ of 38.062°; Ir uses a LiF200 spectroscopic crystal, a voltage of 60 kV, a current of 50 mA, a counting time of 90 s, and a 2θ of 39.216°; Ru uses a LiF220 spectroscopic crystal, a voltage of 60 kV, a current of 50 mA, a counting time of 90 s, and a 2θ of 26.123°; Ta uses a LiF200 spectroscopic crystal, a voltage of 60 kV, a current of 50 mA, a counting time of 90 s, and a 2θ of 44.416°;

[0042] Step S33. Select the elements Pt, Ir, Ru and Ta to be tested, set the display result to the element; set the test condition parameters, modify the counting time, test voltage / current, 2θ and collimator; create angle scanning and energy testing, and modify the angle and energy window; under the working conditions of XRF, analyze the fluorescence intensity and background intensity of Pt, Ir, Ru and Ta in the prepared standard sample, and perform linear regression on the concentration c of the element according to the ratio I of the fluorescence intensity of the analysis line of the element to be tested to the background intensity, and obtain the working curve of the element to be tested;

[0043] Step S34. Regression and fitting of the curve: select the analysis elements Pt, Ir, Ru and Ta respectively, the curve type is a linear curve, and the linear fitting is automatically performed. The difference is controlled to be less than 1% of the sample content, and the linear regression coefficient is greater than 0.999; after removing the points with large errors, the regression correlation coefficient can be improved, and it is generally greater than 0.9999 after adjustment; in order to improve the accuracy of the test results near a certain point, the weight of the point can be changed. When the linear range is large, the curve segmentation can be selected to improve the accuracy of the test results;

[0044] In Example 1, the differences are all less than 1%, the linear regression coefficient Pt is 0.999965, Ir is 0.999974, Ru is 0.999995, Ta is 0.999995, and no curve segmentation is set.

[0045] Step S4. Test the ratio of the fluorescence intensity of the sample to be tested to the background intensity by an X-ray fluorescence spectrometer, and determine the Pt, Ir, Ru, and Ta concentrations of the sample to be tested based on the standard curve between the ratio of the fluorescence intensity to the background intensity in step S3 and the concentrations of Pt, Ir, Ru, and Ta.

[0046] The content of platinum, iridium, ruthenium and tantalum in the electrocatalyst was calculated according to the following equation:

[0047]

[0048] W(M) is the precious metal content in the electrocatalyst (%), W(M) is the XRF equipment detection value (%), m Al2O3 is the weighing value of aluminum oxide, m 样品 is the weight of the electrocatalyst.

[0049] Example 2

[0050] A method for determining the metal content in a PEM electrocatalyst comprises the following steps:

[0051] Step S1. Take a 20mL ceramic crucible, dry it in an oven at 105°C to constant weight, put it in a drying oven and cool it to room temperature, weigh a certain amount of 1002# electrocatalyst, put it in a ceramic crucible, put the ceramic crucible in a 105°C oven, dry it for 2h, take it out and put it in a drying oven to cool to room temperature, and calculate the moisture content ω of the electrocatalyst; take two grinding boxes dedicated to vibration ball mills, weigh 5.000g of alumina, weigh 0.0779g of the dried 1002# electrocatalyst, record the weighed weight m, mix the electrocatalyst and alumina in the grinding box, add steel balls, grind the sample 3 times with a vibration ball mill, each time for 1 minute, with a 2-minute interval in between, take out the ground sample, and bag it in a ziplock bag to obtain a mixed powder;

[0052] Step S2. Use an electronic balance to accurately weigh 3 g of the mixed powder, press the tablet with a plastic ring of a tablet press, set the pressure to 20 MPa, and continue for 15 seconds. After the pressing is completed, remove the sample to obtain the sample to be tested and wait for further testing;

[0053] Step S3: placing the sample to be tested into the XRF device for automatic testing;

[0054] Step S4. Test the ratio of the fluorescence intensity to the background intensity of the sample to be tested by an X-ray fluorescence spectrometer, and determine the Pt, Ir, Ru, and Ta concentrations of the sample to be tested based on the standard curve between the ratio of the fluorescence intensity to the background intensity in step S3 of Example 1 and the concentrations of Pt, Ir, Ru, and Ta.

[0055] The content of platinum, iridium, ruthenium and tantalum in the electrocatalyst was calculated according to the following equation:

[0056]

[0057] W(M) is the precious metal content in the electrocatalyst (%), W(M) is the XRF equipment detection value (%), m Al2O3 is the weighing value of aluminum oxide, m 样品 is the weight of the electrocatalyst.

[0058] Example 3

[0059] A method for determining the metal content in a PEM electrocatalyst comprises the following steps:

[0060] Step S1. Take a 20mL ceramic crucible, dry it in an oven at 105°C to constant weight, put it in a drying oven and cool it to room temperature, weigh a certain amount of 1003# electrocatalyst, and put it in the ceramic crucible; put the ceramic crucible in a 105°C oven and dry it for 2h, take it out and put it in a drying oven to cool to room temperature, and calculate the moisture content ω of the electrocatalyst; take two grinding boxes dedicated to vibration ball mills, weigh 5.000g of alumina, weigh 0.1004g of the dried 1003# electrocatalyst, write down the weighed weight m, mix the electrocatalyst and alumina in the grinding box, add steel balls, grind the sample 3 times with a vibration ball mill, each time for 1 minute, with a 2-minute interval in between, take out the ground sample, and bag it in a ziplock bag to obtain a mixed powder;

[0061] Step S2. Use an electronic balance to accurately weigh 3 g of the mixed powder, use a tablet press, a plastic ring to tablet, set the pressure to 20 MPa, and continue for 15 seconds. After the pressing is completed, remove the sample to obtain the sample to be tested and wait for further testing;

[0062] Step S3. Place the sample to be tested into the XRF device for automatic testing;

[0063] Step S4. Test the ratio of the fluorescence intensity to the background intensity of the sample to be tested by an X-ray fluorescence spectrometer, and determine the Pt, Ir, Ru, and Ta concentrations of the sample to be tested based on the standard curve between the ratio of the fluorescence intensity to the background intensity in step S3 of Example 1 and the concentrations of Pt, Ir, Ru, and Ta.

[0064] The content of platinum, iridium, ruthenium and tantalum in the electrocatalyst was calculated according to the following equation:

[0065]

[0066] W(M) is the precious metal content in the electrocatalyst (%), W(M) is the XRF equipment detection value (%), m Al2O3 is the weighing value of aluminum oxide, m 样品 is the weight of the electrocatalyst.

[0067] The electrocatalysts to be tested in Examples 1-3 were all chloroiridic acid solutions. The electrocatalysts to be tested in Examples 1-3 were tested twice in parallel. The test results are shown in Table 3. The results show that the method has good precision and reproducibility.

[0068] Table 3 Detection effect of precious metals in electrocatalysts

[0069]

[0070] Table 4 Effects of different detection methods on the detection of precious metals in electrocatalysts

[0071] Catalyst type Detection Methods Availability Detection time deviation Pt-C This Act Available 60min ≤3％ GB / T 20042.4 2009 Thermogravimetric method Available 90min ≤5％ GB / T 20042.4 2009ICP method Available 16h ≤3％ Pt-Co-C This Act Available 60min ≤3％ GB / T 20042.4 2009 Thermogravimetric method Unavailable - - GB / T 20042.4 2009ICP method Available 16h ≤3％ Ir-Ti-O This Act Available 60min ≤3％ GB / T 20042.4 2009 Thermogravimetric method Unavailable - - GB / T 20042.4 2009ICP method Unavailable - - Ru-Ru / C This Act Available 60min ≤3％ GB / T 20042.4 2009 Thermogravimetric method Available 90min ≤5％ GB / T 20042.4 2009ICP method Available 16h ＞5％ Ir-Ta-O This Act Available 60min ≤3％ GB / T 20042.4 2009 Thermogravimetric method Unavailable - - GB / T 20042.4 2009ICP method Unavailable - -

[0072] The method of the present invention is compared with the ICP-OES method of GB / T 20042.4 2009 for the contents of Pt, Ru and Ta (Ir is poorly soluble and cannot be detected), and compared with the theoretical concentration. The test results are shown in Table 5. The results show that the difference between the XRF method used in this article and the theoretical concentration detection is less than 3%, except that Ru is easily volatile, and the method is in good agreement.

[0073] Table 5 Comparison between this method and national standard ICP-OES method

[0074]

[0075] It can be concluded from Tables 3-5 that the advantages of the method of the present invention relative to the national standard method are: 1. The detection time is short, and the sample preparation and testing can be completed within one hour; 2. Multiple elements can be detected simultaneously without interference from other elements; 3. No acid dissolution or alkali fusion is required, and the operation is safe and pollution-free; 4. There will be no detection deviation due to incomplete dissolution due to the stability of the precious metals. Iridium oxide is very stable and cannot be completely dissolved by acids and alkalis. Ruthenium trichloride is very volatile, resulting in loss during the sample preparation process, affecting the test results.

[0076] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for determining the metal content in a PEM electrocatalyst, characterized in that: The following steps are involved: Step S1. drying the electrocatalyst, then mixing the dried electrocatalyst with alumina powder, and ball milling to obtain a mixed powder; Step S2. Pressing the mixed powder into a sample to be tested by a tablet press; Step S3. Prepare standard samples of different concentrations of Pt, Ir, Ru, and Ta respectively, and use an X-ray fluorescence spectrometer to test the ratio of the fluorescence intensity to the background intensity of the standard samples of different concentrations of Pt, Ir, Ru, and Ta, so as to obtain a standard curve between the ratio of the fluorescence intensity to the background intensity and the concentrations of Pt, Ir, Ru, and Ta; Step S4. Test the ratio of the fluorescence intensity of the sample to be tested to the background intensity by an X-ray fluorescence spectrometer, and determine the Pt, Ir, Ru, and Ta concentrations of the sample to be tested based on the standard curve between the ratio of the fluorescence intensity to the background intensity in step S3 and the concentrations of Pt, Ir, Ru, and Ta.

2. The method for determining the metal content in a PEM electrocatalyst according to claim 1, characterized in that: In step S1, the drying temperature is 100°C-160°C, and the drying time is 1-3h.

3. The method for determining the metal content in a PEM electrocatalyst according to claim 1, characterized in that: In step S1, the mass ratio of the electrocatalyst to the alumina powder is 0.05-0.20:3-7.

4. The method for determining the metal content in a PEM electrocatalyst according to claim 1, characterized in that: The number of ball milling in step S1 is 1-3 times, the time of each ball milling is 30 seconds to 120 seconds, and the next ball milling is performed after each ball milling for 1-2 minutes.

5. The method for determining the metal content in a PEM electrocatalyst according to claim 1, characterized in that: In step S2, the tablet press has a pressing pressure of 20-60 MPa and a pressing time of 5-30 seconds.

6. The method for determining the metal content in a PEM electrocatalyst according to claim 1, characterized in that: The preparation of standard samples of different concentrations of Pt, Ir, Ru and Ta in step S3 specifically includes: mixing standard solutions containing known concentrations of Pt, Ir, Ru and Ta with carbon powder, and then drying them in an oven at 100°C-160°C to obtain standard samples, wherein the contents of Pt, Ir, Ru and Ta in the standard samples increase gradually.

7. The method for determining the metal content in a PEM electrocatalyst according to claim 1, characterized in that: In step S3, the parameters of the X-ray fluorescence spectrometer when testing Pt are: using LiF200 spectroscopic crystal, voltage is 30-60kV, current is 50-80mA, counting time is 45 s -120s, and 2θ is 38.062°; the parameters when testing Ir are: using LiF200 spectroscopic crystal, voltage is 30-60kV, current is 50-80mA, counting time is 45 s -120s, and 2θ is 39.216°.

8. The method for determining the metal content in a PEM electrocatalyst according to claim 1, characterized in that: In step S3, the parameters of the X-ray fluorescence spectrometer when testing Ru are: using LiF220 spectroscopic crystal, voltage 30-60kV, current 50-80mA, counting time 45 s -120s, 2θ is 26.123°; the parameters when testing Ta are: using LiF200 spectroscopic crystal, voltage 30-60kV, current 50-80mA, counting time 90 s, 2θ is 44.416°.

9. The method for determining the metal content in a PEM electrocatalyst according to claim 1, characterized in that: The method for determining the metal content in the PEM electrocatalyst is suitable for detecting samples in which the precious metal content in the PEM electrocatalyst is 10%-90% of the dry powder mass.

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