A polymer-coated pt / c catalyst with a vacancy interlayer and a preparation method and application thereof

Abstract

The application discloses a polymer-coated Pt / C catalyst with a vacancy interlayer and a preparation method and application thereof, and belongs to the technical field of electrocatalysts for fuel cells and preparation thereof. The application solves the problem that Nafion-SO3H is adsorbed on the surface of Pt to cause catalyst poisoning under the working condition of a fuel cell for the existing Pt / C catalyst. Firstly, a layer of nano Cu(OH)2 precursor product is uniformly coated on the surface of the Pt / C catalyst by controlling the content of a copper source and pH value. Secondly, a polymer thin film which does not need to be sintered and is rich in amino groups which can selectively isolate-SO3H is coated on the surface by adjusting the pH value and reaction temperature, and in-situ polymerization of an amino-containing polymer monomer is carried out on the surface of the precursor product by a simple stirring method. Finally, a vacancy interlayer is created between the coating layer and the catalyst by sacrificing a hard template, so that the steric hindrance effect between-SO3H and the catalyst is increased.

Description

Technical Field

[0001] This invention relates to a polymer-coated Pt / C catalyst with vacancy sandwich layers, its preparation method and application, belonging to the technical field of electrocatalysts for fuel cells and their preparation. Background Technology

[0002] Fuel cells are considered ideal for next-generation energy conversion due to their readily available raw materials, pollution-free byproducts, and high theoretical energy density. Among them, proton exchange membrane fuel cells (PEMFCs) have moderate operating temperatures, simple reactions, and low costs, making them the most likely fuel cell system to become the next-generation power supply device for transportation equipment.

[0003] The oxygen reduction reaction (ORR) at the cathode of PEMFCs is the bottleneck limiting the performance release of the system. This is due to the slow kinetics of the ORR reaction and the deactivation and poisoning of the catalyst after long cycling. Although Pt-based catalysts are more expensive, they are still the best performing and most commercially available catalysts at present. Therefore, optimizing the catalytic effect of this catalyst in ORR has greater commercial value. A common problem with PEMFCs is that the high activity exhibited by the catalyst in rotating disk electrode (RDE) testing cannot be replicated in actual PEM testing. This is because, under actual PEM operating conditions, Pt particles are more prone to metal atom dissolution and nanoparticle aggregation at high current densities, leading to a decrease in the electrochemically active surface area (ECSA). Secondly, due to the high surface activity of Pt, it adsorbs various toxic substances, causing catalyst deactivation. In RDE testing, all Pt particles are in direct contact with protons and oxygen via ultrapure water. However, in PEM testing, the Pt catalyst is tightly bound to the perfluorosulfonic acid ionomer layer (Nafion). Proton transport and oxygen diffusion can only reach the catalyst surface through Nafion, resulting in greater diffusion resistance. Furthermore, the sulfonic acid groups (-SO3H) in Nafion severely poison Pt sites, significantly reducing the mass activity density (SD). Therefore, improving the stability and poisoning resistance of Pt / C catalysts is a key technology for achieving long-life PEMFC applications.

[0004] Surface coating is a common method to improve catalyst stability and interface modification. Currently, carbon shell coating is the primary method for coating Pt-based catalysts. This coating layer reduces Pt particle agglomeration and dissolution by restricting the migration of active sites, while physically isolating Pt from the electrolyte and reducing the adsorption and desorption of toxic molecules on the Pt surface. However, this method has certain problems: First, the carbon shell coating must undergo a sintering process, during which Pt particles inevitably agglomerate, leading to some activity loss. Second, the thickness and structure of the sintered carbon shell are difficult to control; too thick a shell can mask active sites, while too thin a shell offers no protection, resulting in a complex preparation process. Finally, the carbon shell surface has few functional groups, making selective molecular passage difficult and thus exhibiting weak resistance to toxicity.

[0005] In summary, it is crucial to provide a coating method that does not require sintering, has high mechanical strength, and contains adsorption functional groups. Furthermore, since polymer coating is already widely used in the modification of positive and negative electrode materials for batteries, the structure and physicochemical properties of the coating layer can be precisely controlled by selecting the functional groups of the monomers and the degree of polymerization. Therefore, further applying this method to the coating of Pt-based catalysts for fuel cells holds great promise. Summary of the Invention

[0006] This invention addresses the problem of catalyst poisoning caused by the adsorption of -SO3H from Nafion on the Pt surface under fuel cell operating conditions in existing Pt / C catalysts. It provides a polymer-coated Pt / C catalyst with vacancy interlayers, its preparation method, and its application.

[0007] The technical solution of this invention:

[0008] One objective of this invention is to provide a method for in-situ polymerization of Pt / C catalyst coating, which specifically includes the following steps:

[0009] (1) Pt / C catalyst, buffer solution and anhydrous ethanol were mixed and ultrasonically dispersed. Then an inorganic copper source was added. After adjusting the pH to 9.4 with ammonia, the reaction was stirred. After the reaction was completed, the product was washed and dried to obtain the precursor product of Cu(OH)2 coated Pt / C catalyst.

[0010] (2) Mix the precursor product, buffer solution and amino polymer monomer obtained in (1), adjust the pH to 7.5-9, stir and react for 1-2 hours at 0-20℃, wash away the residual polymer monomer by multiple filtrations with distilled water, and freeze dry with liquid nitrogen to obtain a product with a polymer film coated in situ on the surface of the precursor product.

[0011] (3) HClO4 was added to the product obtained in (2), and Cu(OH)2 was dissolved by heating, stirring and reflux. After reflux, liquid nitrogen was used for freeze drying to obtain a polymer-coated Pt / C catalyst with vacancy interlayer.

[0012] Further specifying, (1) the Pt / C catalyst is a commercial Pt / C catalyst with a loading of 40%.

[0013] Further specifying, the buffer solution in (1) is tris(hydroxymethyl)aminomethane with a concentration of 1.2 mg / mL.

[0014] Further specifying, in (1) the mass-to-volume ratio of Pt / C catalyst, buffer solution and anhydrous ethanol is 20 mg: 10 mL: 5 mL.

[0015] Further specifying, (1) the inorganic copper source is copper nitrate, copper chloride or copper sulfate, and the mass of the added Cu element is 2 to 8% of the mass of the Pt / C catalyst.

[0016] Further specifying, the drying process in (1) is: vacuum drying at 120℃ for 6 hours.

[0017] Further specifying, in (2), the amino polymer monomer is acrylamide, N-vinylacetamide, catechol ethylamine or aniline.

[0018] Further specifying, the buffer solution in (2) is tris(hydroxymethyl)aminomethane with a concentration of 1.2 mg / mL.

[0019] Further specifying, in (2), the mass-to-volume ratio of the precursor product, buffer solution and amino polymer monomer is 20 mg: 10 mL: (20-30) mg.

[0020] Further specifying, (2) the degree of polymerization of the amino polymer monomer is 50-70%.

[0021] Further specified, (3) has a HClO4 concentration of 0.1M and a heating and stirring reflux temperature of 60℃.

[0022] Further specifying, the mass-to-volume ratio of the product obtained in (2) to HClO4 in (3) is 15mg:45ml.

[0023] The second objective of this invention is to provide a polymer-coated Pt / C catalyst with vacancy interlayers prepared by the above method. Specifically, the catalyst uses a Pt / C catalyst as the core, and a polymer coating layer is in situ coated on the surface of the core, with a vacancy interlayer between the core and the polymer coating layer.

[0024] Further specified, the thickness of the polymer coating layer is 1-3 nm.

[0025] Furthermore, the thickness of the vacancy interlayer is less than 2 nm.

[0026] A third objective of this invention is to provide an application of the above-mentioned catalyst, specifically as a cathode catalyst for fuel cells.

[0027] Beneficial effects:

[0028] This invention first controls the copper source content and pH value to uniformly coat a layer of nano-Cu(OH)₂ precursor product onto the surface of a commercial Pt / C catalyst. Then, by adjusting the pH value and reaction temperature, and using simple stirring, amino-containing polymeric monomers are polymerized in situ onto the precursor product surface, resulting in a polymer film that does not require sintering and is rich in amino groups that selectively isolate -SO₃H. Finally, a vacancy interlayer is created between the coating layer and the catalyst using a sacrificial hard template, increasing the steric hindrance effect between -SO₃H and the catalyst. Compared with existing technologies, this invention has at least the following advantages:

[0029] (1) This invention successfully prepared a commercial platinum-carbon catalyst with vacancy interlayers and specific functional groups by coating the surface of a sacrificial hard template and then dissolving the template. The coating layer and its vacancy interlayer have a certain physical isolation effect, inhibiting the aggregation of Pt particles and reducing the adsorption of -SO3H on the catalyst surface through steric hindrance effect. At the same time, the amino group supported by the coating layer has a certain basicity and has a certain characteristic adsorption capacity for acidic groups -SO3H through the Coulomb interaction between charges, thereby greatly improving the catalyst's anti-poisoning performance.

[0030] (2) This invention selects an amino polymer as the polymer coating layer. The amino groups in the amino polymer form a conjugated structure with the aromatic rings in the backbone, which facilitates electron transition and transport. Simultaneously, the amino groups are partially charged in acidic systems, leading to electron transfer on their surface. These two factors combined give the amino polymer excellent electrical conductivity. Furthermore, the presence of numerous robust C-C and CN bonds in the polymer system ensures molecular stability. The amino groups, acting as endothermic groups, further mitigate the thermal decomposition reaction of the polymer, reducing its decomposition temperature to above 200°C. The actual operating temperature of a proton exchange membrane fuel cell is 80°C, far below the lower limit of thermal decomposition. Therefore, this coating layer exhibits excellent electrical conductivity and high thermal stability under fuel cell operating conditions.

[0031] (3) In this invention, the polymer coating layer is not directly polymerized on the catalyst surface. Instead, a sacrificial Cu(OH)2 template is added between the catalyst and the polymer. After further etching, nanoscale vacancies are created between the catalyst layer and the coating layer, thereby improving the steric hindrance effect and enhancing the isolation effect of the coating layer on the surface of the -SO3H poisoned catalyst.

[0032] (4) The coating method provided by the present invention does not require sintering. While ensuring that the catalyst activity is almost undamaged, it improves the catalyst’s anti-poisoning performance through the synergistic effect of ion adsorption and physical isolation. Moreover, the coating layer structure can be precisely controlled by monomer design and polymerization degree, can be prepared in large quantities, has universality, and can be applied to a variety of commercial platinum-based catalysts. Attached Figure Description

[0033] Figure 1 SEM images (at different magnifications) of the Pt / C@PDA catalyst prepared in Example 1;

[0034] Figure 2 CV test curves of the Pt / C@PDA catalyst prepared in Example 1, and Pt / C@C and Pt / C prepared in Comparative Example 1;

[0035] Figure 3 LSV test curves for Pt / C dispersions with different Nafion contents;

[0036] Figure 4 LSV test curves of Pt / C@C prepared for Comparative Example 1 in dispersions with different Nafion contents;

[0037] Figure 5 LSV test curves of Pt / C@PDA prepared in Example 1 in dispersions with different Nafion contents. Detailed Implementation

[0038] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0039] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0040] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0041] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, all materials, reagents, methods, and instruments used are conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art. Furthermore, all solid and liquid reagents used are of analytical grade.

[0042] Example 1

[0043] The process for preparing the Pt / C@PDA catalyst in this embodiment is as follows:

[0044] Step 1: Weigh 20 mg of 40% loaded commercial Pt / C catalyst into a 20 mL sample vial, add 10 mL of 1.2 mg / mL tris(hydroxymethyl)aminomethane buffer and 5 mL of anhydrous ethanol, seal completely, and sonicate in a high-power sonicator for 30 min to obtain a uniform dispersion.

[0045] Step 2: Place the sample vial containing the dispersion on a magnetic stirrer, add 4.56 mg Cu(NO3)2·3H2O, stir for 60 min, and after it is fully dissolved, adjust the pH of the solution to 9.4 with ammonia water, and then continue stirring for 12 h. After stirring, wash the product and dry it under vacuum at 120 °C for 6 h to obtain Cu(OH)2-coated Pt / C catalyst.

[0046] Step 3: Add 20 mg of the product from Step 2 to a 20 mL sample vial, add 10 mL of 1.2 mg / mL tris(hydroxymethyl)aminomethane buffer, use catechol ethylamine as the polymer monomer, control the polymerization temperature at 0–10 °C using an ice bath, adjust the pH of the dispersion to 8.3–8.7 using ammonia, and the mass ratio of the added polymer monomer to the product from Step 2 is 30 mg: 20 mg. Maintain constant temperature and pH, and continue stirring for 1.5 h to complete the in-situ polymerization coating on the catalyst surface.

[0047] Step 4: The solution obtained in Step 3 is repeatedly filtered three times with distilled water to wash away the buffer solution and residual polymer monomers. The resulting product is placed in a self-sealing bag and rapidly frozen in liquid nitrogen, then freeze-dried for 24 hours. The resulting powder is the polydopamine-coated platinum-carbon catalyst.

[0048] Step 5: Add 15 mg of the product obtained in Step 4 to 45 mL of 0.1 M HClO4, stir at 60 °C for 6 h, reflux to dissolve Cu(OH)2 in the interlayer, place the product after reflux in a self-sealing bag for liquid nitrogen quick-freezing, and freeze-dry for 24 h. The resulting powder is the final product, a commercial Pt / C catalyst with vacancy interlayer coated with polydopamine, abbreviated as Pt / C@PDA.

[0049] Example 2

[0050] The process for preparing the Pt / C@PDA catalyst in this embodiment is as follows:

[0051] Step 1: Weigh 20 mg of 40% loaded commercial Pt / C catalyst into a 20 mL sample vial, add 10 mL of 1.2 mg / mL tris(hydroxymethyl)aminomethane buffer and 5 mL of anhydrous ethanol, seal completely, and sonicate in a high-power sonicator for 30 min to obtain a uniform dispersion.

[0052] Step 2: Place the sample vial containing the dispersion on a magnetic stirrer, add 4.56 mg Cu(NO3)2·3H2O, stir for 60 min, and after it is fully dissolved, adjust the pH of the solution to 9.4 with ammonia water, and then continue stirring for 12 h. After stirring, wash the product and dry it under vacuum at 120 °C for 6 h to obtain Cu(OH)2-coated Pt / C catalyst.

[0053] Step 3: Add 20 mg of the product from Step 2 to a 20 mL sample vial, add 10 mL of 1.2 mg / mL tris(hydroxymethyl)aminomethane buffer solution, use aniline as the polymer monomer, control the polymerization temperature at 0–10 °C using an ice bath, adjust the pH of the dispersion to 7.3–7.8 using ammonia, and the mass ratio of the added polymer monomer to the product from Step 2 is 30 mg: 20 mg. Add 1 mL of 3% hydrogen peroxide solution as a polymerization initiator, maintain a constant temperature and pH, and continue stirring for 1.5 h to complete the in-situ polymerization coating on the catalyst surface.

[0054] Step 4: The solution obtained in Step 3 is repeatedly filtered three times with distilled water to wash away the buffer solution and residual polymer monomers. The resulting product is placed in a self-sealing bag and rapidly frozen in liquid nitrogen, then freeze-dried for 24 hours. The resulting powder is a platinum-carbon catalyst coated with polyaniline.

[0055] Step 5: 15 mg of the product obtained in Step 4 is added to 45 mL of 0.1 M HClO4 and stirred at 60 °C for 6 h. The Cu(OH)2 in the interlayer is dissolved by reflux. After the reflux is completed, the product is placed in a self-sealing bag and rapidly frozen in liquid nitrogen. After freeze-drying for 24 h, the resulting powder is the final product, a commercial Pt / C catalyst with vacancy interlayer coated with polyaniline.

[0056] Comparative Example 1

[0057] The process for preparing the Pt / C@C catalyst in this comparative example is as follows:

[0058] Step 1: Weigh 20 mg of 40% loaded commercial Pt / C catalyst into a 20 mL sample vial, add 10 mL of 1.2 mg / mL tris(hydroxymethyl)aminomethane buffer and 5 mL of anhydrous ethanol, seal completely, and sonicate in a high-power sonicator for 30 min to obtain a uniform dispersion.

[0059] Step 2: Place the sample vial containing the dispersion on a magnetic stirrer, add 4.56 mg Cu(NO3)2·3H2O, stir for 60 min, and after it is fully dissolved, adjust the pH of the solution to 9.4 with ammonia water, and then continue stirring for 12 h. After stirring, wash the product and dry it under vacuum at 120 °C for 6 h to obtain Cu(OH)2-coated Pt / C catalyst.

[0060] Step 3: Add 20 mg of the product from Step 2 to a 20 mL sample vial, add 10 mL of 1.2 mg / mL tris(hydroxymethyl)aminomethane buffer, use catechol ethylamine as the polymer monomer, control the polymerization temperature at 0–10 °C using an ice bath, adjust the pH of the dispersion to 8.3–8.7 using ammonia, and the mass ratio of the added polymer monomer to the product from Step 2 is 30 mg: 20 mg. Maintain constant temperature and pH, and continue stirring for 1.5 h to complete the in-situ polymerization coating on the catalyst surface.

[0061] Step 4: The solution obtained in Step 3 is repeatedly filtered three times with distilled water to wash away the buffer solution and residual polymer monomers. The resulting product is placed in a self-sealing bag and rapidly frozen in liquid nitrogen, then freeze-dried for 24 hours. The resulting powder is the polydopamine-coated platinum-carbon catalyst.

[0062] Step 5: Add 15 mg of the product obtained in Step 4 to 45 mL of 0.1 M HClO4, stir at 60 °C for 6 h, reflux to dissolve Cu(OH)2 in the interlayer, place the product after reflux in a self-sealing bag for liquid nitrogen quick-freezing, and freeze-dry for 24 h. The resulting powder is the commercial Pt / C catalyst with vacancy interlayer coated with polydopamine, abbreviated as Pt / C@PDA.

[0063] Step six: Grind the powder obtained in step five in a mortar for 20 minutes, then transfer it to a tube furnace and heat it to 900°C at a heating rate of 30°C / min under an argon atmosphere. Anneal it at this temperature for 1 hour to carbonize the coating layer on the catalyst surface. The resulting powder is the commercial platinum-carbon catalyst with nitrogen-doped carbon coating, abbreviated as Pt / C@C.

[0064] Application examples

[0065] (1) The surface microstructure of the Pt / C@PDA prepared in Example 1 was characterized, and the results are as follows: Figure 1As shown in the figure, the surface of the Pt particles is uniformly coated with a coating layer with a thickness of 1.5 nm. This coating layer did not collapse due to the dissolution of the Cu(OH)2 hard template.

[0066] (2) The CV test curves of the Pt / C@PDA catalyst prepared in Example 1, the Pt / C@C prepared in Comparative Example 1, and the raw material Pt / C are shown below. Figure 2 As shown, the test atmosphere was a 0.1M HClO4 solution saturated with argon, the voltage range was 0.03–1.2V, and the scan rate was 50mV / s. Figure 2 It can be seen that the two hydrogen regions of the CV curves of the commercial Pt / C catalyst with vacancy sandwich layer and polydopamine prepared in Example 1 (without sintering) almost overlap with those of the commercial Pt / C catalyst, indicating that the in-situ polymerization coating did not reduce the electrochemical active area of ​​the catalyst, and the activity was almost unaffected. Further sintering of the polymer coating layer of Pt / C@PDA prepared in Example 1 (i.e., the Pt / C@C catalyst prepared in Comparative Example 1) resulted in a significant decrease in the current density in the hydrogen region of the CV curve, indicating that the electrochemical active area of ​​the catalyst decreased and the current density in the double layer region decreased. This suggests that after sintering, some mesopores of the catalyst powder were blocked, resulting in a decrease in the equivalent capacitance of the catalyst. Comparing the CV curves of Example 1 and Comparative Example 1, it is clear that the unsintered amino polymer-coated platinum-carbon catalyst has higher catalytic potential.

[0067] (3) The poisoning resistance of the catalyst was tested by the loss of half-wave potential in the LSV test curves of the catalyst in dispersions with different Nafion contents (Group 2, which increased the proportion of Nafion solution by 10 times compared to Group 1, was used to investigate the tolerance of the platinum-carbon catalyst to the poisoning of -SO3H groups before and after coating). The composition ratio of the dispersion in Group 1 was catalyst:water:isopropanol:5% Nafion solution 4mg:3mL:1mL:4mL. The composition ratio of the dispersion in Group 2 was catalyst:water:isopropanol:5% Nafion solution 4mg:3mL:1mL:40mL.

[0068] The LSV of the Pt / C catalyst in two groups was tested at a scan rate of 10 mV / s within the range of 0.03–1.2 V. The test results are as follows: Figure 3 As shown, by Figure 3 It can be seen that the half-wave potential loss of Pt / C catalyst is huge when the Nafion content increases dramatically, which indicates that the uncoated Pt / C catalyst has poor tolerance to -SO3H.

[0069] The Pt / C@PDA catalyst prepared in Example 1 was subjected to LSV testing in two groups of dispersions at a scan rate of 10 mV / s between 0.03 and 1.2 V. The test results are as follows: Figure 5As shown, by Figure 5 It can be seen that, with a dramatic increase in Nafion content, the half-wave potential of this catalyst is almost unaffected compared to the Pt / C catalyst, indicating that the amino polymer coating greatly enhances the catalyst's tolerance to -SO3H. At the same time, compared to the original Pt / C catalyst, the initial half-wave potential of this catalyst is almost unchanged (0.87 vs. 0.87 V), and the coating does not reduce the initial activity of the catalyst, thus avoiding the activity loss caused by Pt particle agglomeration.

[0070] The Pt / C@C catalyst prepared in Comparative Example 1 was subjected to LSV testing in two groups of dispersions at a scan rate of 10 mV / s between 0.03 and 1.2 V. The test results are as follows. Figure 4 As shown, by Figure 4 It can be seen that the loss of half-wave potential of the sintered Pt / C@C catalyst is smaller than that of the Pt / C catalyst when the Nafion content increases dramatically. This indicates that the nitrogen-doped carbon coating layer helps to improve the catalyst's tolerance to -SO3H. However, after sintering, the initial half-wave potential of the catalyst is significantly reduced (0.80 vs. 0.87 V) compared to the original catalyst, indicating that the Pt particles have a certain degree of agglomeration and the catalyst activity is greatly reduced.

[0071] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for in-situ polymerization of Pt / C catalyst coating, characterized in that, include: (1) Pt / C catalyst, buffer solution and anhydrous ethanol were mixed and ultrasonically dispersed. Then an inorganic copper source was added. After adjusting the pH to 9.4 with ammonia, the reaction was stirred. After the reaction was completed, the product was washed and dried to obtain the precursor product of Cu(OH)2 coated Pt / C catalyst. (2) Mix the precursor product, buffer solution and amino polymer monomer obtained in (1), adjust the pH to 7.5-9, stir and react for 1-2 h at 0-20℃, wash away the residual polymer monomer by multiple filtrations with distilled water, and freeze dry with liquid nitrogen to obtain a product with a polymer film coated in situ on the surface of the precursor product. (3) HClO4 was added to the product obtained in (2), and Cu(OH)2 was dissolved by heating, stirring and reflux. After reflux, liquid nitrogen was used for freeze drying to obtain a polymer-coated Pt / C catalyst with vacancy interlayer.

2. The method according to claim 1, characterized in that, (1) The Pt / C catalyst is a commercial Pt / C catalyst with a loading of 40%, and the buffer is tris(hydroxymethyl)aminomethane with a concentration of 1.2 mg / mL; the mass-volume ratio of Pt / C catalyst, buffer and anhydrous ethanol is 20 mg: 10 mL: 5 mL.

3. The method according to claim 1, characterized in that, (1) The inorganic copper source is copper nitrate, copper chloride or copper sulfate, and the mass of Cu element added is 2~8% of the mass of Pt / C catalyst.

4. The method according to claim 1, characterized in that, (1) The drying process is: vacuum drying at 120℃ for 6 hours.

5. The method according to claim 1, characterized in that, (2) The amino polymer monomer is acrylamide, N-vinylacetamide, catechol ethylamine or aniline; the buffer is tris(hydroxymethyl)aminomethane with a concentration of 1.2 mg / mL; the mass-volume ratio of the precursor product, buffer and amino polymer monomer is 20 mg: 10 mL: (20-30) mg.

6. The method according to claim 1, characterized in that, (3) The concentration of HClO4 is 0.1M, and the reflux temperature for heating and stirring is 60℃.

7. A polymer-coated Pt / C catalyst with vacancy interlayers prepared by the method according to any one of claims 1 to 6, characterized in that, The catalyst uses a Pt / C catalyst as the core, with a polymer coating layer in situ on the core surface, and a vacancy interlayer between the core and the polymer coating layer.

8. The catalyst according to claim 7, characterized in that, The polymer coating thickness is 1-3 nm; the vacancy interlayer thickness is less than 2 nm.

9. The application of the catalyst according to claim 7 or 8, characterized in that, It can be used directly as a cathode catalyst in fuel cells without the need for high-temperature annealing.

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