Platinum-carbon catalysts and their preparation methods and fuel cells

Abstract

A platinum-carbon catalyst, its preparation method, and a fuel cell are disclosed, belonging to the field of fuel cells. The platinum-carbon catalyst comprises a carbon support and platinum particles supported on the carbon support. The platinum-carbon catalyst is heat-treated at 600℃-700℃ for 0.5-3 hours under an inert atmosphere, and the Zeta potential of the heat-treated platinum-carbon catalyst is measured to be greater than 0. This indicates that the surface of the platinum-carbon catalyst has a stable positive charge, which facilitates a more uniform coverage and thickness of ionic polymers on the surface of the platinum-carbon catalyst during the preparation of the fuel cell catalyst layer. This effectively reduces local oxygen transport resistance and proton conduction resistance in the catalyst layer, thereby improving the performance of the fuel cell.

Description

Technical Field

[0001] This application relates to the field of fuel cells, and more specifically, to a platinum-carbon catalyst, a method for preparing the same, and a fuel cell. Background Technology

[0002] Platinum-carbon catalysts, as a key component of the catalyst layer (CLs) in polymer electrolyte membrane fuel cells (PEMFCS), are considered to have a significant impact on mass transport due to their surface properties, primarily manifested in the distribution of ionic polymers on the catalyst surface. In the catalyst layer, the redox reaction (ORR) occurs only at the catalytically active sites, where Pt directly contacts protons, electrons, and oxygen. Therefore, the uniformity and thickness of the ionic polymer coverage on the catalyst are crucial for providing efficient and shorter transport paths for the gaseous reactant oxygen (O2) and the ORR product water (H2O). Non-uniform ionic polymer distribution not only leads to increased local oxygen transport resistance in thicker areas of the ionic polymer membrane but also increases proton conduction resistance in thinner areas. Summary of the Invention

[0003] This application provides a platinum-carbon catalyst, its preparation method, and a fuel cell. The platinum-carbon catalyst has a highly stable positive charge on its surface, which is beneficial for the uniform coverage and thickness of the ion polymer on its surface when it is mixed with the catalyst. This effectively reduces the local oxygen transport resistance and proton conduction resistance in the catalyst layer, thereby improving the performance of the fuel cell.

[0004] The embodiments of this application are implemented as follows:

[0005] In a first aspect, this application provides a platinum-carbon catalyst comprising a carbon support and platinum particles supported on the carbon support;

[0006] The platinum-carbon catalyst was heat-treated at 600℃-700℃ for 0.5-3 hours under an inert atmosphere, and the Zeta potential of the heat-treated platinum-carbon catalyst was found to be greater than 0. The platinum-carbon catalyst provided in this application has a stable positively charged surface, which facilitates a more uniform coverage and thickness of ionic polymers on the surface of the platinum-carbon catalyst when preparing the catalyst layer for fuel cells. This effectively reduces local oxygen transport resistance and proton conduction resistance in the catalyst layer, thereby improving the performance of the fuel cell.

[0007] In some alternative embodiments, the zeta potential of the platinum-carbon catalyst is 25 mV-40 mV.

[0008] In some alternative embodiments, the pH value of the platinum-carbon catalyst is 6-7; and / or,

[0009] The oxygen content in the platinum-carbon catalyst is 2%-3%; and / or,

[0010] The nitrogen content in the platinum-carbon catalyst is 0%.

[0011] In some alternative embodiments, the platinum particle loading in the platinum-carbon catalyst is 40%-60%.

[0012] In some alternative embodiments, the average particle size of the platinum particles is 2nm-4nm, and the average particle size of the carbon support is 20nm-40nm.

[0013] In a second aspect, this application provides an example of a method for preparing a platinum-carbon catalyst as provided in the first aspect of this application, comprising:

[0014] The platinum-carbon catalyst to be treated, the electrolyte salt, and the solvent are mixed and reacted for 6-24 hours. The mixture is then filtered and dried.

[0015] Electrolyte salts include nitrates.

[0016] The preparation method provided in this application is controllable, and the surface of the obtained platinum-carbon catalyst has a stable positive charge. This makes it easier for the ionic polymer to cover the surface of the platinum-carbon catalyst more uniformly and thickly when preparing the catalyst layer of a fuel cell. This effectively reduces the local oxygen transport resistance and proton conduction resistance in the catalyst layer and improves the performance of the fuel cell.

[0017] In some optional embodiments, the preparation method further includes: heat-treating the dried intermediate product at 600℃-700℃ for 0.5-3h under an inert atmosphere.

[0018] In some optional embodiments, the electrolyte salt includes at least one of sodium nitrate and potassium nitrate;

[0019] Optionally, the mass ratio of platinum-carbon catalyst to electrolyte salt is 1:1-12, or optionally 1:1-10.

[0020] In some alternative embodiments, the solvent includes at least one of water, methanol, ethanol, and N,N-dimethylfuran.

[0021] In some alternative embodiments, the zeta potential of the platinum-carbon catalyst to be treated is less than 0, and can be selected as -10mV to -20mV.

[0022] In a third aspect, this application provides an example of a fuel cell that includes a catalyst layer comprising the platinum-carbon catalyst and an ion polymer provided in the first aspect of this application. Detailed Implementation

[0023] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0024] The following provides a detailed description of the platinum-carbon catalyst, its preparation method, and the fuel cell based on embodiments of this application:

[0025] The first aspect of this application provides a platinum-carbon catalyst, which includes a carbon support and platinum particles supported on the carbon support.

[0026] The platinum-carbon catalyst was heat-treated at 600℃-700℃ for 0.5-3h under an inert atmosphere, and the Zeta potential of the heat-treated platinum-carbon catalyst was found to be greater than 0.

[0027] It is understood that the platinum-carbon catalyst is heat-treated at 600℃-700℃ for 0.5-3 hours under an inert atmosphere, and then the Zeta potential of the heat-treated platinum-carbon catalyst is detected. The heat treatment here is actually a test condition. Since this test condition can remove unstable positive charges without causing a change in charge properties (e.g., negative to positive), when the test result shows that the Zeta potential of the heat-treated platinum-carbon catalyst is greater than 0, it can be concluded that before the heat treatment, the positive charges are stably bound to the surface of the platinum-carbon catalyst provided in this application.

[0028] Understandably, since the detection conditions do not cause a change in charge properties (e.g., from negative to positive), that is, the surface of the platinum-carbon catalyst before heat treatment has a positive charge (i.e., it is a cation), that is, the Zeta potential of the platinum-carbon catalyst before heat treatment is greater than 0.

[0029] The inert atmosphere includes, but is not limited to, at least one of nitrogen and argon.

[0030] For example, the heat treatment temperature is any one of 600°C, 625°C, 650°C, 675°C, 700°C, or between any two of these values.

[0031] For example, the heat treatment time is any value of 0.5h, 1h, 1.5h, 2h, 2.5h, 3h or between any two values.

[0032] In summary, the platinum-carbon catalyst provided in this application has a stable positive charge on its surface, which makes it easier for ionic polymers to cover the surface of the platinum-carbon catalyst and the coverage thickness to be more uniform when the catalyst layer of the fuel cell is prepared. This effectively reduces the local oxygen transport resistance and proton conduction resistance in the catalyst layer and improves the performance of the fuel cell.

[0033] In some alternative embodiments, the zeta potential of the platinum-carbon catalyst is 25 mV-40 mV.

[0034] The platinum-carbon catalyst has a high zeta potential and a large number of positive charges on its surface. This is beneficial when it is mixed with ionomers, as it allows for a more uniform coverage and thickness of the ionomers on the surface of the platinum-carbon catalyst. This effectively reduces the local oxygen transport resistance and proton conduction resistance in the catalyst layer, thereby improving the performance of the fuel cell.

[0035] For example, the zeta potential of the platinum-carbon catalyst is any value of 25mV, 26mV, 28mV, 30mV, 32mV, 35mV, 37mV, or 40mV, or between any two values.

[0036] In some alternative embodiments, the pH value of the platinum-carbon catalyst is 6-7; and / or, the oxygen content in the platinum-carbon catalyst is 2%-3%; and / or, the nitrogen content in the platinum-carbon catalyst is 0%.

[0037] Based on the above parameters, it can be seen that the surface of the platinum-carbon catalyst does not contain modified groups such as amino groups, that is, the positive charge on the surface of the platinum-carbon catalyst is not introduced by introducing modified groups such as amino groups.

[0038] In some alternative embodiments, the platinum particle loading in the platinum-carbon catalyst is 40%-60%.

[0039] Within the aforementioned range, the platinum-carbon catalyst exhibits a high platinum particle loading, which meets the application requirements and is beneficial for improving catalytic efficiency.

[0040] For example, the loading of platinum particles in the platinum-carbon catalyst is any one of 40%, 43%, 45%, 48%, 50%, 53%, 55%, 57%, 60%, or between any two of these values.

[0041] In some alternative embodiments, the average particle size of the platinum particles is 2nm-4nm, and the average particle size of the carbon support is 20nm-40nm.

[0042] Under the above parameters, the platinum particles in the platinum-carbon catalyst have a small particle size, resulting in a large specific surface area and better catalytic effect.

[0043] A second aspect of this application provides a method for preparing the platinum-carbon catalyst provided in the first aspect of this application, comprising:

[0044] The platinum-carbon catalyst to be treated, the electrolyte salt, and the solvent are mixed and reacted for 6-24 hours. The mixture is then filtered and dried.

[0045] Electrolyte salts include nitrates.

[0046] It is understood that the platinum-carbon catalyst to be treated refers to the platinum-carbon catalyst before it has been modified by the preparation method of this application. It can be prepared by itself or purchased directly from the market, and there is no limitation here.

[0047] The solvent is used to disperse the platinum-carbon catalyst to be treated and to dissolve the electrolyte salt. By mixing the platinum-carbon catalyst to be treated, the electrolyte salt and the solvent, the cations ionized by the platinum-carbon catalyst and the electrolyte salt are fully contacted, adsorbed and combined through liquid-phase mixing. This is beneficial for the cations to modify the surface of the platinum-carbon catalyst to be treated, and to obtain a platinum-carbon catalyst with a uniformly distributed positive charge on the surface as an intermediate product. Most of the positive charge in the intermediate product is stably bound to its surface.

[0048] In other words, the preparation method provided in this application is controllable, and the surface of the obtained platinum-carbon catalyst has a stable positive charge. This makes it easier for the ionic polymer to cover the surface of the platinum-carbon catalyst more uniformly and thickly when preparing the catalyst layer of a fuel cell. This effectively reduces the local oxygen transport resistance and proton conduction resistance in the catalyst layer and improves the performance of the fuel cell.

[0049] In some alternative embodiments, the preparation method further includes: heat-treating the dried intermediate product at 600℃-700℃ for 0.5-3h under an inert atmosphere.

[0050] It is understandable that the heat treatment in the preparation method is not a testing method, but a part of the preparation method. Through the above heat treatment, the few unstable positive charges and impurities on the surface of the intermediate product can be effectively removed without destroying the structure of the platinum-carbon catalyst, so as to obtain a platinum-carbon catalyst with fewer impurities and a more stable zeta potential. When applied to fuel cells, it is beneficial to make the ion polymer coverage on the surface of the platinum-carbon catalyst more uniform in terms of coverage degree and thickness, thereby effectively reducing the local oxygen transport resistance and proton conduction resistance in the catalyst layer and improving the performance of the fuel cell.

[0051] The inert atmosphere includes, but is not limited to, at least one of argon and nitrogen.

[0052] For example, the heat treatment temperature is any one of 600°C, 625°C, 650°C, 675°C, 700°C, or between any two of these values.

[0053] For example, the heat treatment time is any value of 0.5h, 1h, 1.5h, 2h, 2.5h, 3h or between any two values.

[0054] Nitrates as electrolyte salts include, but are not limited to, at least one of sodium nitrate, potassium nitrate, lithium nitrate, etc.

[0055] In some alternative embodiments, the electrolyte salt includes at least one of sodium nitrate and potassium nitrate.

[0056] The aforementioned electrolyte salts can be fully ionized in the solvent, and have a good effect on modifying the surface positive charge of the platinum-carbon catalyst to be treated.

[0057] In some alternative embodiments, the mass ratio of platinum carbon catalyst to electrolyte salt is 1:1-12.

[0058] By adjusting the mass ratio of the two, the zeta potential of the final platinum-carbon catalyst can be adjusted to have a higher zeta potential, which is beneficial for the ionomer to have a more uniform coverage and thickness on the surface of the platinum-carbon catalyst when it comes into contact with the ionomer.

[0059] For example, the mass ratio of platinum carbon catalyst to electrolyte salt is any one of 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or between any two of these values.

[0060] Optionally, the mass ratio of platinum-carbon catalyst to electrolyte salt is 1:1-10.

[0061] In some alternative embodiments, the solvent includes at least one of water, methanol, ethanol, and N,N-dimethylfuran.

[0062] The solvents mentioned above have good dispersing properties and can all ionize electrolyte salts to produce cations.

[0063] In some alternative embodiments, the zeta potential of the platinum-carbon catalyst to be treated is less than 0.

[0064] It is understandable that the Zeta potential of the platinum-carbon catalyst to be treated is less than 0, which means that the surface of the platinum-carbon catalyst to be treated has a negative charge (i.e., anion).

[0065] Optionally, the zeta potential of the platinum-carbon catalyst to be treated is -10mV to -20mV.

[0066] The surface of the platinum-carbon catalyst to be treated with a zeta potential of -10mV to -20mV has a large number of negative charges adsorbed. Therefore, by adjusting the concentration of the electrolyte solution, the conversion of its surface charge can be effectively controlled, which is beneficial to obtaining a platinum-carbon catalyst with a higher zeta potential.

[0067] For example, the zeta potential of the platinum-carbon catalyst is any value of -10mV, -11mV, -12mV, -13mV, -14mV, -15mV, -16mV, -17mV, -18mV, -19mV, or -20mV, or between any two values.

[0068] For example, the platinum-carbon catalyst with the aforementioned zeta potential can be prepared using a chlorine-containing platinum precursor, which has a large number of negative charges on its surface (Cl). - This allows the zeta potential of the prepared platinum-carbon catalyst to reach -10mV to -20mV.

[0069] A third aspect of this application provides a fuel cell comprising a catalyst layer, the catalyst layer comprising the platinum-carbon catalyst and the ionomer provided in the first aspect of this application.

[0070] The following detailed description of the platinum-carbon catalyst, its preparation method, and fuel cell of this application is provided in conjunction with the embodiments.

[0071] In the following examples and comparative examples, the platinum-carbon catalyst to be treated, referred to as the Pt / C catalyst to be treated, has a Zeta potential of -17.63 mV, a Pt loading of 50%, a pH of 6.8, an oxygen content of 2.8%, a nitrogen content of 0%, an average particle size of 3 nm for the platinum particles, and an average particle size of 31 nm for the carbon support.

[0072] Example 1

[0073] A Pt / C catalyst, the preparation method of which includes:

[0074] 1 g of the Pt / C catalyst to be treated was dispersed in 20 ml of water, and then 20 ml of a 5 mol / L sodium nitrate solution was added (the mass ratio of Pt / C catalyst to sodium nitrate (NaNO3:Pt / C) was 8.5). After stirring for 12 h, the mixture was filtered and washed. The obtained solid was dried in a vacuum drying oven at 80 °C to obtain the intermediate product.

[0075] The intermediate product was heat-treated at 700℃ for 3 hours under an argon atmosphere to obtain a Pt / C catalyst.

[0076] Example 2

[0077] A Pt / C catalyst, the preparation method of which includes:

[0078] 1 g of the Pt / C catalyst to be treated was dispersed in 20 ml of water, and then 20 ml of a 7 mol / L sodium nitrate solution was added (the mass ratio of Pt / C catalyst to sodium nitrate (NaNO3:Pt / C) was 11.9). After stirring for 12 h, the mixture was filtered and washed. The obtained solid was then dried in a vacuum drying oven at 80 °C to obtain the intermediate product.

[0079] The intermediate product was heat-treated at 700℃ for 3 hours under an argon atmosphere to obtain a Pt / C catalyst.

[0080] Example 3

[0081] A Pt / C catalyst, the preparation method of which includes:

[0082] 1 g of the Pt / C catalyst to be treated was dispersed in 20 ml of water, and then 20 ml of a 3 mol / L sodium nitrate solution was added (the mass ratio of Pt / C catalyst to sodium nitrate (NaNO3:Pt / C) was 5.1). After stirring for 12 h, the mixture was filtered and washed. The obtained solid was dried in a vacuum drying oven at 80 °C to obtain the intermediate product.

[0083] The intermediate product was heat-treated at 700℃ for 3 hours under an argon atmosphere to obtain a Pt / C catalyst.

[0084] Example 4

[0085] A Pt / C catalyst, the preparation method of which includes:

[0086] 1 g of the Pt / C catalyst to be treated was dispersed in 20 ml of water, and then 20 ml of a 1 mol / L sodium nitrate solution was added (the mass ratio of Pt / C catalyst to sodium nitrate (NaNO3:Pt / C) was 1.7). After stirring for 12 h, the mixture was filtered and washed. The obtained solid was then dried in a vacuum drying oven at 80 °C to obtain the intermediate product.

[0087] The intermediate product was heat-treated at 700℃ for 3 hours under an argon atmosphere to obtain a Pt / C catalyst.

[0088] Example 5

[0089] A Pt / C catalyst, the preparation method of which includes:

[0090] 1 g of the Pt / C catalyst to be treated was dispersed in 20 ml of N,N-dimethylfuran, and then 20 ml of a 5 mol / L sodium nitrate solution was added (the mass ratio of Pt / C catalyst to sodium nitrate (NaNO3:Pt / C) was 8.5). After stirring for 12 h, the mixture was filtered and washed, and the obtained solid was dried in a vacuum drying oven at 80 °C to obtain the intermediate product.

[0091] The intermediate product was heat-treated at 600℃ for 1 hour under an argon atmosphere to obtain a Pt / C catalyst.

[0092] Comparative Example 1

[0093] 1g of the Pt / C catalyst to be treated was heat-treated at 700℃ for 3h in an argon atmosphere to obtain the Pt / C catalyst.

[0094] The Zeta potential of the Pt / C catalyst was <0, specifically -12.53 mV.

[0095] In other words, although heat treatment alone can increase the Zeta potential of the Pt / C catalyst, its Zeta potential is still negative. That is, heat treatment alone has no substantial effect on the surface charge of the Pt / C catalyst.

[0096] Comparative Example 2

[0097] 1 g of the Pt / C catalyst to be treated was dispersed in 20 ml of water, and then 20 ml of 5 mol / L nitric acid solution was added. The mixture was stirred at 80 °C for 3 h, filtered and washed, and the obtained solid was dried in a vacuum drying oven at 80 °C to obtain an intermediate product. The zeta potential of the intermediate product was tested to be >0, specifically 12.61 mV.

[0098] The intermediate product was heat-treated at 700℃ for 3 hours under an argon atmosphere to obtain a Pt / C catalyst with a Zeta potential of <0 (specifically -7.36mV).

[0099] According to Comparative Example 2, the charge adsorption of Pt / C catalyst is unstable when treated with nitric acid solution.

[0100] Comparative Example 3

[0101] A Pt / C catalyst, the preparation method of which includes:

[0102] 1g of the Pt / C catalyst to be treated was dispersed in 20ml of water, and then 20ml of a 5mol / L sodium chloride solution was added. After stirring for 12h, the mixture was filtered and washed. The obtained solid was dried in a vacuum drying oven at 80℃ to obtain the intermediate product.

[0103] The intermediate product was heat-treated at 700℃ for 3 hours under an argon atmosphere to obtain a Pt / C catalyst with a Zeta potential of <0 (specifically -2.53mV).

[0104] According to Comparative Example 3, it contains Cl - The electrolyte solution has a strong adsorption of negative charges, which weakens the modification effect of positive potential.

[0105] Experimental Example 1

[0106] Using the Pt / C catalysts used as raw materials in each example and comparative example as a basic control group, the relevant parameters and Zeta potentials of the basic control group and the Pt / C catalysts prepared in Examples 1-5 and Comparative Examples 1-3 were tested.

[0107] The specific test method for the Zeta potential of Pt / C catalyst is as follows: A certain amount of Pt / C catalyst is dispersed in water, and after sonication for 10 minutes, the Zeta potential is tested using a ColloidMetrix CMX particle potentiometric titration analyzer. The test temperature is 25℃, and each sample is measured three times, and the average value is taken.

[0108] In Examples 1-5 and Comparative Examples 1-3, the Pt / C catalyst had a Pt loading of 50%, a pH of 6.8, a nitrogen content of 0%, and an average particle size of 31 nm for the carbon support. The Zeta potential test results of the Pt / C catalyst, as well as the oxygen content and the average particle size of the platinum particles, changed. The specific test results are shown in Table 1.

[0109] Table 1. Zeta potential test results, oxygen content, and average particle size of the Pt / C catalyst.

[0110]

[0111] As shown in Table 1, the preparation method provided in this application can prepare platinum-carbon catalysts with highly stable positive charges on the surface.

[0112] As can be seen from the comparison of Examples 1-4, increasing the concentration of sodium nitrate can further increase the value of the surface charge Zeta potential. However, when the concentration is 5 mol / L or above, even if the concentration is further increased, the Zeta potential value remains basically constant. Therefore, the sodium nitrate concentration of Example 1 is preferred.

[0113] Experimental Example 2

[0114] Adsorption experiment of perfluorosulfonic acid ionomer:

[0115] The self-adsorption capacity of the catalyst and the ionomer was determined by an adsorption experiment on perfluorosulfonic acid ionomers. The specific operation included: immersing 100 mg of Pt / C catalyst from each example and the comparative example in an aqueous solution of perfluorosulfonic acid (PFSA) ionomer with a mass concentration of 24% to 25%, stirring for 30 min, allowing it to settle, separating the Pt / C catalyst, and drying it. The dried Pt / C catalyst was then weighed. If the mass increase of the Pt / C catalyst was 5% to 50%, it indicated that the Pt / C catalyst had a certain self-adsorption capacity for PFSA ionomers. If the mass increase of the Pt / C catalyst was <5%, it indicated that it had no self-adsorption capacity for PFSA ionomers.

[0116] Oxygen transport test:

[0117] Single cells were prepared using the Pt / C catalysts obtained in the above embodiments and comparative examples.

[0118] A single cell with an effective area of ​​5 square centimeters was analyzed using a Model 850e fuel cell test system (Scribner, USA). Pt / C catalyst, deionized water, isopropanol, and 5% (by weight) Nafion were mixed into a slurry by shearing. The Pt / C catalyst slurry was ultrasonically sprayed onto the cathode, and the anode used was a commercial 50 wt% Pt / C. Pt was present at a concentration of 0.1 mg / cm³. 2 The content of [something] is loaded on the cathode and anode.

[0119] The limiting current density of single cells activated at 100% humidity was tested. The battery operating conditions and test procedures are as follows: 1. Condition stabilization: At 0.7V, the anode was supplied with 0.5 slpm of hydrogen gas, and the cathode with 1.0 slpm of a nitrogen-oxygen mixture, stabilizing for 30 minutes. 2. Constant potential load test of the limiting current: Stabilizing at 0.7V for 5 minutes, starting at 0.4V, testing every 0.1V, stabilizing for 5 minutes at each point from 0.4V to 0.1V. Each curve was tested twice, and the data were recorded. 3. Under a certain pressure, polarization curve tests were performed for the above voltage mode with different oxygen concentrations. The oxygen concentration of the cathode gas was tested in ascending order. (The cathode was an oxygen-nitrogen mixture with oxygen concentrations of 1%, 2%, and 3%).

[0120] Data processing:

[0121] 1. Plot the oxygen concentration on the horizontal axis and the measured limiting current density on the vertical axis. The slope of the straight line is inversely proportional to the total oxygen transport resistance value Rtotal.

[0122] Where Rtotal = 4FP / RT*1 / b;

[0123] Rtotal—Oxygen transport resistance;

[0124] b—The slope of the graph showing the relationship between limiting current density and oxygen concentration;

[0125] F—Faraday constant (96485 C / mol);

[0126] R—gas constant (8.314 Jmol⁻¹k⁻¹);

[0127] T—Battery temperature;

[0128] P—Absolute pressure value.

[0129] The more uniform the ionomer coverage and the more uniform the thickness, the lower the oxygen transport resistance. Therefore, lower oxygen transport resistance indicates more uniform ionomer coverage and a more uniform thickness.

[0130] The test results are shown in Table 2.

[0131] Table 2 Test Results

[0132] Mass increase after adsorption experiment Oxygen transport resistance / s / cm Example 1 50％ 0.66 Example 2 50％ 0.68 Example 3 30％ 0.78 Example 4 10％ 0.83 Example 5 35％ 0.75 Comparative Example 1 0％ 1.02 Comparative Example 2 2％ 0.93 Comparative Example 3 5％ 0.93

[0133] As shown in Table 2, compared with the comparative example, the platinum-carbon catalyst in this embodiment showed a significant increase in mass and a significant decrease in oxygen transport resistance after the adsorption experiment. That is, the platinum-carbon catalyst in this embodiment, when mixed with the ion polymer, is conducive to a more uniform coverage degree and thickness of the ion polymer on the surface of the platinum-carbon catalyst, effectively reducing the local oxygen transport resistance in the catalyst layer and improving the performance of the fuel cell.

[0134] As can be seen from Examples 1-4, the higher the Zeta potential of the platinum-carbon catalyst surface, the greater the density of positive charge on its surface, and the more perfluorosulfonic acid ionomers are adsorbed through the Coulomb force between the positive and negative charges, resulting in a smaller oxygen transport resistance in the single cell and a more uniform coverage of the corresponding ionomers.

[0135] The above are merely specific embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A platinum-carbon catalyst, characterized in that, The catalyst includes a carbon support and platinum particles supported on the carbon support, wherein the zeta potential of the platinum-carbon catalyst is greater than 0. The platinum-carbon catalyst was heat-treated at 600℃-700℃ for 0.5-3h under an inert atmosphere, and the Zeta potential of the heat-treated platinum-carbon catalyst was measured to be greater than 0. The platinum-carbon catalyst was prepared by the following method: The platinum-carbon catalyst to be treated, the electrolyte salt, and the solvent are mixed and reacted for 6-24 hours, then filtered and dried; wherein the electrolyte salt includes at least one of sodium nitrate and potassium nitrate.

2. The platinum-carbon catalyst according to claim 1, characterized in that, The zeta potential of the platinum-carbon catalyst after heat treatment is 25mV-40mV.

3. The platinum-carbon catalyst according to claim 1, characterized in that, The pH value of the platinum-carbon catalyst is 6-7; and / or; The oxygen content in the platinum-carbon catalyst is 2%-3%; and / or, The nitrogen content in the platinum-carbon catalyst is 0%.

4. The platinum-carbon catalyst according to claim 1, characterized in that, The platinum particles in the platinum-carbon catalyst have a loading of 40%-60%.

5. The platinum-carbon catalyst according to claim 1, characterized in that, The average particle size of the platinum particles is 2nm-4nm, and the average particle size of the carbon support is 20nm-40nm.

6. A method for preparing a platinum-carbon catalyst as described in any one of claims 1-5, characterized in that, include: The platinum-carbon catalyst to be treated, the electrolyte salt, and the solvent are mixed and reacted for 6-24 hours. The mixture is then filtered and dried. The electrolyte salt includes at least one of sodium nitrate and potassium nitrate.

7. The preparation method according to claim 6, characterized in that, The preparation method further includes: heat-treating the dried intermediate product at 600℃-700℃ for 0.5-3h under an inert atmosphere.

8. The preparation method according to claim 6, characterized in that, The mass ratio of the platinum-carbon catalyst to the electrolyte salt is 1:1-12.

9. The preparation method according to claim 6, characterized in that, The mass ratio of the platinum-carbon catalyst to the electrolyte salt is 1:1-10.

10. The preparation method according to claim 6, characterized in that, The solvent includes at least one of water, methanol, ethanol, and N,N-dimethylfuran.

11. The preparation method according to claim 6, characterized in that, The zeta potential of the platinum-carbon catalyst to be treated is less than 0.

12. The preparation method according to claim 6, characterized in that, The zeta potential of the platinum-carbon catalyst to be treated is -10 mV to -20 mV.

13. A fuel cell, characterized in that, It includes a catalyst layer, which comprises the platinum-carbon catalyst according to any one of claims 1-5 and an ion polymer.

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