Hollow mesoporous carbon sphere prepared based on confinement polymerization method, loaded rare earth metal doped platinum alloy catalyst and preparation method

Abstract

The invention relates to a hollow mesoporous carbon sphere prepared based on a confinement polymerization method and a preparation method of a platinum alloy catalyst loaded by the hollow mesoporous carbon sphere and doped with rare earth metal. The method comprises the following steps: by taking mesoporous silica as a template, introducing an initiator and a small molecular organic matter precursor into mesopores, and carrying out confinement polymerization in the mesopores to obtain a silica / polymer composite; carrying out high-temperature calcination and etching treatment on the complex to obtain hollow mesoporous carbon spheres; the carbon sphere is used as a carrier to load a platinum alloy doped with rare earth metal. The hollow mesoporous carbon spheres prepared by the method have good spherical morphology and mesoporous channels and high specific surface area, and the problems of non-uniform morphology, unobvious mesopores and the like in a traditional method are solved. After platinum alloy particles doped with rare earth metal are loaded on the carbon spheres, the problems of agglomeration, wide particle size distribution, poor performance and the like of the platinum alloy particles are solved.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemistry, and particularly relates to a hollow mesoporous carbon sphere prepared by a confinement polymerization method, a platinum alloy catalyst doped with rare earth metals loaded thereon, and a preparation method thereof. Background Art

[0002] With the continuous growth of global energy demand and the urgent need for sustainable energy, electrochemical energy conversion and storage devices have become the focus of attention. A proton exchange membrane fuel cell (PEMFC) is a device that can directly convert chemical energy into electrical energy, and has advantages such as high energy conversion efficiency and clean products, and is regarded as one of the most promising green energy conversion devices in the 21st century. The cathode oxygen reduction reaction (ORR) in PEMFC plays a crucial role in the battery performance. Although the energy conversion process of this reaction is very efficient, its kinetic reaction rate is relatively slow, and a catalyst with high activity and high stability is required to promote the reaction rate. Therefore, the research and improvement of catalysts have become an important direction for improving the performance of PEMFC and promoting its commercial application.

[0003] Currently, the most commonly used electrocatalyst for fuel cells is noble metal platinum particles supported on a carrier with high conductivity, Vulcan XC-72(R). However, its specific surface area is relatively low. During the electrocatalytic process, due to the weak confinement of the carbon carrier on the platinum-based nanoparticles, agglomeration of the particles usually occurs, resulting in poor activity and stability of the platinum-carbon catalyst. And mesopores with a suitable size distribution are beneficial to the dispersion of platinum-based nanoparticles on the carbon carrier, and can significantly inhibit the growth rate of the particles during the synthesis and electrochemical testing processes. Therefore, the development of a carbon with a suitable mesoporous structure, high specific surface area and high conductivity has become the current research focus.

[0004] Ferdi et al. synthesized mesoporous carbon spheres using divinylbenzene as a precursor, effectively inhibiting the agglomeration of platinum-based nanoparticles and giving them a relatively narrow size distribution. However, the morphology of the prepared mesoporous carbon spheres is partially damaged, indicating that the spherical structure is not completely preserved. This phenomenon may be due to the preferential reaction of the azobisisobutyronitrile initiator with the stilbene molecules outside the mesoporous SiO 2 template to form oligomers. These oligomers are unable to enter the mesopores inside the mesoporous SiO 2 template due to their large molecular weight, resulting in non-uniform spherical morphology after carbonization. And a uniform morphology and a pore structure with concentrated distribution are crucial for the subsequent loading of platinum alloy. Therefore, a better method is needed to prepare mesoporous carbon spheres.

[0005] In addition, designing suitable platinum-based nanoparticles is another key factor in improving the performance of ORR catalysts. Doping rare earth metals into alloys formed by platinum and transition metals can effectively regulate the electronic structure of platinum, thereby improving catalytic activity (Li M, Zhao Z, Xia Z, et al. ACS Catal. 2020, 10(5), 3018-3026; Liu X, Zhao Z, Liang J, et al. Angewandte Chemie International Edition, 2023: e202302134). By doping a small amount of rare earth metal elements, such as Ce, Nd, Gd, Er, La, Ga, etc., into alloy catalysts formed by platinum and transition metals, the charge distribution and electronic structure on the surface of the electrocatalyst can be significantly changed, thereby enhancing the ORR electrocatalytic activity of the electrocatalyst. However, the catalyst performance reported by predecessors still cannot meet the requirements for further applications, and the oxygen reduction performance of platinum-based alloys still needs to be further improved.

[0006] Chinese Patent Application CN115842138A discloses a preparation method of a fuel cell platinum alloy catalyst. This method prepares carbon-coated particles on the basis of commercial platinum-carbon: an alloy core and a nitrogen-doped carbon shell containing single atoms. Its mass activity is better than that of unmodified commercial platinum-carbon, and the catalyst has excellent cycle stability. After cycling at a low potential for a period of time, its mass activity is higher than its initial mass activity. However, the performance of the prepared catalyst is more dependent on the performance of the commercial catalyst used, and it cannot fundamentally solve the problems of catalyst performance and stability.

[0007] According to the above, in the existing preparation schemes of fuel cell catalysts, the carbon-based carriers are mostly activated carbon powder or other carbon carriers that are difficult to prepare and have poor morphology retention. Platinum-based catalysts prepared with these carriers will have problems such as uneven particle distribution and easy agglomeration. Summary of the Invention

[0008] To achieve the above object, the present invention proposes a hollow mesoporous carbon sphere prepared by a confinement polymerization method and a platinum alloy catalyst doped with rare earth metals and a preparation method thereof.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A preparation method of a hollow mesoporous carbon sphere prepared by a confinement polymerization method, using mesoporous silica as a template through a confinement polymerization method, successively introducing an initiator and a small molecule organic matter precursor into its mesopores (that is, first adding the initiator and then adding the small molecule organic matter precursor) to carry out confinement polymerization in the pores; and then obtaining the hollow mesoporous carbon sphere through high-temperature calcination and etching treatment.

[0011] The hollow mesoporous carbon sphere is:

[0012] (1) Preparation of silica / polymer composite by confinement polymerization method: Under vacuum conditions, an initiator and a small molecule organic precursor are successively added to mesoporous silica, and then the initiator initiates the confinement polymerization of the small molecule organic precursor in the mesoporous channels of silica, so that the formed polymer fills the mesoporous channels of silica, forming a silica / polymer composite;

[0013] (2) Preparation of hollow mesoporous carbon spheres: The silica / polymer composite in step (1) is placed in a tubular furnace and calcined at high temperature under the protection of an inert atmosphere. After cooling to room temperature, it is then etched, and then washed and dried to obtain hollow mesoporous carbon spheres.

[0014] Furthermore, under vacuum conditions, an initiator and a small molecule organic precursor are successively added to mesoporous silica, and then the initiator initiates the confinement polymerization of the small molecule organic precursor in the mesoporous channels of silica for 0.5 - 24 h, so that the formed polymer fills the mesoporous channels of silica, forming a silica / polymer composite; then, it is placed in a tubular furnace and calcined at high temperature at 700 - 1600 °C for 2 - 6 h under the protection of an inert atmosphere. After calcination, it is cooled to room temperature and etched at 25 - 90 °C for 0.1 - 48 h, and then washed and dried to obtain hollow mesoporous carbon spheres.

[0015] The initiator is one or more of ferric chloride, ferric nitrate, ammonium persulfate, potassium persulfate, concentrated sulfuric acid, boron trifluoride - diethyl ether solution, azobisisobutyronitrile;

[0016] The small molecule organic precursor is a mixture of one or more of aniline, pyrrole, indene, acenaphthene;

[0017] The calcination atmosphere is nitrogen or argon;

[0018] The solution used in the etching process is one or more of potassium hydroxide solution, sodium hydroxide solution, hydrochloric acid solution, sulfuric acid solution, nitric acid solution, hydrofluoric acid solution.

[0019] A hollow mesoporous carbon sphere prepared by the said method, which is a hollow mesoporous carbon sphere with a good spherical morphology and obvious mesoporous structure prepared according to the said method.

[0020] An application of the said hollow mesoporous carbon sphere, the application of the hollow mesoporous carbon sphere in the preparation of fuel cell catalysts.

[0021] A supported rare earth metal - doped platinum alloy catalyst, the catalyst is a rare earth metal - doped platinum alloy supported on the said hollow mesoporous carbon sphere, thus obtaining the catalyst; wherein, the theoretical content of platinum accounts for 5 - 30% of the mass of the final catalyst.

[0022] A preparation method of the described catalyst, adding platinum salt, transition metal salt, and rare earth metal salt solutions into the described hollow mesoporous carbon spheres, achieving equal-volume impregnation to form a slurry, subjecting it to ultrasonic treatment, and then drying it in a freeze dryer. Subsequently, the dried product is placed in a tubular furnace and calcined under an H 2 / Ar mixed gas atmosphere. After cooling to room temperature, the catalyst can be obtained.

[0023] The platinum salt, transition metal salt, and rare earth metal salt are added to a solvent; among them, for the platinum salt, transition metal salt, and rare earth metal salt, the dosage distribution is that the platinum salt and the transition metal salt adopt a consistent alloy phase ratio of 5:1 to 1:5. As the doping element of the rare earth metal element, the ratio of the platinum salt to the rare earth metal element is 10:1 to 2:1, and the ratios are all molar atomic ratios;

[0024] The solvent is one or more of distilled water, methanol, ethanol, propanol, and isopropanol; the transition metal salt is one or more of Co salt, Ni salt, Fe salt, and Cu salt; the rare earth metal salt is one or more of Gd salt, La salt, Nd salt, Ga salt, and Er salt.

[0025] The ratio of the H 2 / Ar mixed gas is 1 / 99 to 20 / 80; the temperature of the calcination treatment is 300 to 1000 °C; the time of the calcination treatment is 0.5 to 10 h.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] In the present invention, the hollow mesoporous carbon spheres prepared by the confinement polymerization method have a good spherical morphology and an obvious mesoporous structure. The confinement polymerization method can enable the polymer to fully fill the mesoporous channels of the silica template, and a perfect mesoporous structure can be obtained through the processes of polymerization - carbonization - etching. On the basis of these hollow mesoporous carbon spheres, loading platinum alloy nanoparticles doped with rare earth metals can effectively regulate the electronic structure of platinum by the rare earth metal, thereby improving the catalytic performance of the composite catalyst; specifically:

[0028] (1) In the method of the present invention, the confinement polymerization method is adopted. First, the initiator and the small molecule organic matter precursor enter the mesoporous channels of the mesoporous silica template, and then polymerization is carried out, which can make the polymer fill the mesoporous channels of the template. It avoids the problem that after polymerization outside the pores, the polymer cannot enter the template pores due to the too large molecular chain;

[0029] (2) After the method of the present invention performs calcination and etching treatment on the silica / polymer composite, hollow mesoporous carbon spheres can be obtained. These carbon spheres have accessible internal spaces, high specific surface areas, and high strength, which are beneficial for the transport of reactants and by-products in the oxygen reduction reaction. In addition, the rich mesoporous structure lays a foundation for the uniform dispersion of the subsequently loaded metal particles, and can also solve the problem of agglomeration of platinum-based nanoparticles during the electrochemical process, thereby improving the stability of the catalyst.

[0030] (3) Doping the platinum alloy nanoparticles with rare earth metal elements by the method of the present invention can regulate the surface charge and electronic structure of platinum, thereby enhancing the electrocatalytic activity of the catalyst.

[0031] (4) The catalyst prepared by the method of the present invention has better catalytic activity than commercial platinum carbon and has good application prospects in fields such as fuel cells and industrial catalysis. Description of the Drawings

[0032] Figure 1 In the middle is the SEM image of the hollow mesoporous carbon spheres prepared in Example 1 of the present invention. Among them, a and b are low-magnification scanning electron microscope pictures of the mesoporous carbon, and c and d are high-magnification scanning electron microscope pictures of the mesoporous carbon.

[0033] Figure 2 is the TEM image of the Gd-doped Pt 3 Co alloy catalyst loaded on the hollow mesoporous carbon spheres prepared in Example 1 of the present invention. Among them, a is the high-resolution transmission electron microscope picture of the catalyst, and b is the high-angle annular dark-field transmission electron microscope picture of the catalyst.

[0034] Figure 3 is the Gd-doped Pt 3 XRD comparison chart of the Co alloy catalyst and the commercial 20wt% JM Pt / C catalyst.

[0035] Figure 4 is the TEM image of the Nd-doped Pt 3 Fe alloy loaded on the hollow mesoporous carbon spheres prepared in Example 2 of the present invention. Among them, a is the low-magnification transmission electron microscope picture of the catalyst, and b is the high-magnification transmission electron microscope picture of the catalyst.

[0036] Figure 5 is the Nd-doped Pt 3 particle size distribution chart of the Fe alloy.

[0037] Figure 6 is the TEM image of the mesoporous carbon prepared in Comparative Example 1 of the present invention.

[0038] Figure 7 is the Gd-doped Pt synthesized in Example 1 of the present invention3 Comparison chart of oxygen reduction curves between Co alloy catalyst and commercial 20wt% JM Pt / C.

[0039] Figure 8 Fuel cell performance comparison chart of the catalyst prepared in Example 1 of the present invention and commercial Pt / C.

[0040] Figure 9 Theoretical calculation chart of the excellent performance of the catalyst prepared in Example 1 of the present invention; among them, a is the construction of various metal structure models, b is the oxygen adsorption energy of various structures, c is the surface energy of various structures. Detailed implementation manners

[0041] The following further illustrates the detailed implementation manners of the present invention in conjunction with examples. It should be noted that the detailed implementation manners described here are only for explaining and interpreting the present invention and are not limited to the present invention.

[0042] The present invention is based on the preparation of hollow mesoporous carbon spheres by a confinement polymerization method, and the preparation of rare earth element-doped platinum alloy catalysts using the carbon spheres as carriers.

[0043] The nano-hollow mesoporous carbon spheres use mesoporous silica as a template, and an initiator and a small molecule organic matter precursor are introduced into the mesopores to perform confinement polymerization in the pores; the polymerized composite is sequentially subjected to high-temperature calcination and etching treatment.

[0044] The obtained nano-hollow mesoporous carbon spheres are hollow mesoporous carbon hollow spheres with a complete spherical morphology, good mesoporous channels, accessible internal space, and high specific surface area. The confinement polymerization method solves the problems of uneven morphology and unclear mesopores in the traditional method.

[0045] The catalyst is the preparation of a rare earth metal-doped platinum alloy catalyst supported on the hollow mesoporous carbon spheres.

[0046] Furthermore, using it as a carrier can help disperse platinum-based particles and keep their particle size distribution range narrow. Even further, doping rare earth metals into the platinum-based alloy can finely adjust the d electron orbital structure of platinum atoms, change the electronic structure and charge distribution, thereby improving the catalytic activity. Therefore, the obtained catalyst has a carbon carrier with a high specific surface area, high conductivity, and a suitable mesoporous structure, and adopts a strategy of doping rare earth elements to precisely regulate the d orbital energy level of platinum atoms to obtain an oxygen reduction catalyst with high catalytic activity, solving problems such as platinum particle agglomeration, wide particle size distribution, and poor performance.

[0047] Example 1

[0048] (1) Under vacuum conditions, add 2 mL of a 0.2 M ethanol solution of anhydrous ferric chloride to 2 g of mesoporous silica template. After vacuum drying at 50 °C, add 1.8 mL of indene, and then polymerize at room temperature for 10 h. Place the polymerization product in a tube furnace and calcine at 1000 °C for 2 h under an argon atmosphere. After cooling to room temperature, etch the carbonized sample successively in sodium hydroxide and hydrochloric acid solutions, etch at 60 °C for 12 h, and then obtain hollow mesoporous carbon spheres after washing with water and drying (see Figure 1 ).

[0049] (2) Prepare aqueous solutions of chloroplatinic acid, cobalt nitrate, and gadolinium nitrate at 200 mg / mL. Use a pipette to take 100 μL of chloroplatinic acid solution, 20 μL of cobalt nitrate, and 20 μL of gadolinium nitrate solution, and add them to 30 mg of the hollow mesoporous carbon spheres in step (1) to achieve equal-volume impregnation to form a slurry. After ultrasonic treatment for 2 h, place it in a freeze dryer for drying. Subsequently, place the dried product in a tube furnace and calcine at 700 °C for 4 h under an atmosphere of 5% H 2 / Ar mixed gas. After cooling to room temperature, the final catalyst can be obtained (see Figure 2 and 3 ).

[0050] As can be seen from Figure 1 , hollow mesoporous carbon with a perfect spherical morphology can be prepared through Example 1, and the carbon spheres have a good mesoporous structure, and the mesopores are evenly distributed on the spherical surface.

[0051] As can be seen from Figure 2 the TEM image, Gd-doped Pt 3 Co alloy nanoparticles with a narrow particle size distribution can be obtained through Example 1, and they are evenly dispersed on the hollow mesoporous carbon sphere support without obvious agglomeration.

[0052] As can be seen from Figure 3 the XRD comparison chart, the XRD full width at half maximum of the catalyst prepared through Example 1 is wider than that of JM Pt / C. According to the Scherrer formula, its particle size is smaller than that of the commercial catalyst.

[0053] Example 2

[0054] (1) Under vacuum conditions, add 3.2 mL of a 1 M aqueous solution of ammonium persulfate to 3 g of mesoporous silica template. After vacuum drying, add 2.7 mL of pyrrole, and then polymerize at room temperature for 6 h. Place the polymerization product in a tube furnace and calcine at 900 °C for 4 h under a nitrogen atmosphere. After cooling to room temperature, etch the carbonized sample successively in hydrofluoric acid solution, etch at 25 °C for 24 h, and then obtain hollow mesoporous carbon spheres after washing with water and drying.

[0055] (2) Prepare an aqueous solution of chloroplatinic acid, cobalt nitrate, and gadolinium nitrate at 200 mg / mL. Use a pipette to take 100 μL of the chloroplatinic acid solution, 20 μL of cobalt nitrate, and 20 μL of gadolinium nitrate solution, and add them to the hollow mesoporous carbon spheres in step (1) to achieve equal-volume impregnation to form a slurry. After ultrasonic treatment, place it in a freeze dryer for drying. Subsequently, place the dried product in a tube furnace and calcine it at 600 °C for 6 h in an atmosphere of 5% H 2 / Ar mixed gas. After cooling to room temperature, the final catalyst can be obtained (see Figure 4 and 5 ).

[0056] From Figure 4 the TEM image, it can be seen that the platinum nanoparticles prepared in Example 2 are evenly dispersed on the hollow mesoporous carbon spheres, and no obvious agglomeration phenomenon appears.

[0057] From Figure 5 the particle size distribution diagram, it can be seen that the average particle size of the nanoparticles prepared in Example 2 is 2.74 nm, and the particle size distribution is narrow.

[0058] Comparative Example 1

[0059] Under vacuum conditions, add 1.8 mL of indene to 2 g of the mesoporous silica template, and then add 0.2 mL of boron trifluoride-ether solution. Polymerize at room temperature for 10 h. Place the polymerization product in a tube furnace and calcine it at 1000 °C for 2 h in an argon atmosphere. After cooling to room temperature, place the carbonized sample in a sodium hydroxide solution for etching, etch at 60 °C for 12 h, and then wash and dry to obtain a carbon product polymerized outside the pores.

[0060] Prepare an aqueous solution of chloroplatinic acid, cobalt nitrate, and gadolinium nitrate at 200 mg / mL. Use a pipette to take 100 μL of the chloroplatinic acid solution, 20 μL of cobalt nitrate, and 20 μL of gadolinium nitrate solution, and add them to 30 mg of the hollow mesoporous carbon spheres in step (1) to achieve equal-volume impregnation to form a slurry. After ultrasonic treatment for 2 h, place it in a freeze dryer for drying. Subsequently, place the dried product in a tube furnace and calcine it at 700 °C for 4 h in an atmosphere of 5% H 2 / Ar mixed gas. After cooling to room temperature, the final Gd-doped Pt 3 Co mesoporous carbon catalyst (Gd-Pt 3 Co@HMS-O) can be obtained.

[0061] From Figure 6 the TEM image, it can be known that the carbon synthesized in Comparative Example 1 has no regular morphology, indicating that the confinement polymerization method of the present invention is beneficial to obtaining hollow mesoporous carbon spheres with a perfect spherical morphology and a uniform mesoporous distribution.

[0062] Comparative Example 2

[0063] Disperse 2 g of SiO2 into 30 mL of mesitylene solution, add 0.5 g of AIBN initiator and 2 mL of indene, stir at 75 °C for 24 h, and centrifuge to obtain the polymerization product. Place the polymerization product in a tube furnace, calcine it at 1000 °C for 2 h under an argon atmosphere, cool it to room temperature, then place the carbonized sample in a sodium hydroxide solution for etching, etch at 60 °C for 12 h, and then obtain the carbon product after washing with water and drying.

[0064] Prepare aqueous solutions of chloroplatinic acid, cobalt nitrate, and gadolinium nitrate with a concentration of 200 mg / mL. Use a pipette to take 100 μL of chloroplatinic acid solution, 20 μL of cobalt nitrate, and 20 μL of gadolinium nitrate solution, and add them to 30 mg of hollow mesoporous carbon spheres in step (1) to achieve equal-volume impregnation to form a slurry. After ultrasonic treatment for 2 h, place it in a freeze dryer for drying. Subsequently, place the dried product in a tube furnace and calcine it at 700 °C for 4 h under a 5% H 2 / Ar mixed gas atmosphere. After cooling to room temperature, the final solution method for preparing Gd-doped Pt 3 Co mesoporous carbon catalyst (Gd-Pt 3 Co@HMS-Sol) can be obtained.

[0065] At the same time, perform electrode tests on the catalysts obtained in Example 1, Comparative Example 1, and Comparative Example 2 above and a commercial platinum-carbon catalyst (20% JM Pt / C). Specifically:

[0066] Take 5 mg of the Gd-doped Pt 3 Co obtained in Example 1 and 20% JM Pt / C catalyst and disperse them in 2 mL of Nafion / ethanol mixed solution respectively, and ultrasonicate for 30 min. Take 5 μL of the mixed solution and drop it onto a glassy carbon electrode with a diameter of 4 mm respectively. After drying, use linear sweep voltammetry to test the half-wave potential of the sample on a rotating disk electrode. The electrolyte during the test is O 2 saturated 0.1 M HClO 4 solution, the rotation speed is 1600 rpm, and the sweep rate is 10 mV / s. Compare the polarization curves obtained from the electrochemical test with the polarization curve of 20% commercial platinum-carbon measured under the same test conditions to evaluate the catalytic activity of the catalyst.

[0067] According to Figure 7 the oxygen reduction curve in Figure 8From the fuel cell test data, it can be concluded that the half-wave potential of the catalyst prepared in Example 1 is better than that of the commercial JM Pt / C catalyst, showing excellent oxygen reduction catalytic activity. The synthesized catalysts in Comparative Example 1 and Comparative Example 2 have poor performance because the morphology consistency of the prepared carbon support is poor, and the restriction on the alloy during the high-temperature reduction process is low, resulting in larger alloy particles and poor oxygen reduction performance. Figure 2 and Figure 3 It shows that the synthesized catalyst has a smaller particle size, and the particle size is slightly smaller than that of the commercial 20% JM Pt / C. This means that more active sites of the platinum-based particles are exposed, improving the utilization rate of platinum. In addition, due to the mesoporous structure, the catalyst can prevent the shedding and aggregation of active particles during the oxygen reduction reaction, further enhancing the stability of the catalyst. Figure 9 Theoretical calculations show that the introduction of the rare earth element gadolinium can reduce the surface energy of the alloy and enhance the oxygen binding energy, thereby improving the oxygen reduction performance. These factors together contribute to the excellent oxygen reduction catalytic activity of the prepared catalyst.

[0068] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for preparing hollow mesoporous carbon spheres based on confined polymerization, characterized in that: Through the confined polymerization method, mesoporous silica is used as a template, and initiators and small molecule organic precursors are introduced into its mesopores in succession to cause confined polymerization in the pores; then hollow mesoporous carbon spheres are obtained through high-temperature calcination and etching treatment.

2. The method for preparing hollow mesoporous carbon spheres based on confined polymerization method according to claim 1, characterized in that: The hollow mesoporous carbon sphere is: (1) Preparation of silica / polymer composites by confined polymerization: under vacuum conditions, an initiator and a small molecule organic precursor are added to the mesoporous silica in sequence, and then the initiator initiates the confined polymerization of the small molecule organic precursor in the mesoporous channels of the silica, so that the formed polymer fills the mesoporous channels of the silica, forming a silica / polymer composite; (2) Preparation of hollow mesoporous carbon spheres: The silica / polymer composite in step (1) is placed in a tubular furnace and calcined at high temperature under the protection of an inert atmosphere. After cooling to room temperature, the composite is etched and then washed and dried to obtain hollow mesoporous carbon spheres.

3. The method for preparing hollow mesoporous carbon spheres based on confined polymerization method according to claim 2, characterized in that: Under vacuum conditions, an initiator and a small molecule organic precursor are successively added to the mesoporous silica, and then the initiator triggers the confined polymerization of the small molecule organic precursor in the mesoporous channels of the silica for 0.5 to 24 hours, so that the formed polymer fills the mesoporous channels of the silica to form a silica / polymer complex; then, it is placed in a tubular furnace and calcined at 700 to 1600°C for 2 to 6 hours under the protection of an inert atmosphere, cooled to room temperature after calcination, and etched at 25 to 90°C for 0.1 to 48 hours, and then washed and dried to obtain hollow mesoporous carbon spheres.

4. The method for preparing hollow mesoporous carbon spheres based on confined polymerization method according to claim 3, characterized in that: The initiator is one or more of ferric chloride, ferric nitrate, ammonium persulfate, potassium persulfate, concentrated sulfuric acid, boron trifluoride-ether solution, and azobisisobutyronitrile; The small molecule organic precursor is one or a mixture of aniline, pyrrole, indene, acenaphthene; The calcination atmosphere is nitrogen or argon; The solution used in the etching process is one or more of potassium hydroxide solution, sodium hydroxide solution, hydrochloric acid solution, sulfuric acid solution, nitric acid solution, and hydrofluoric acid solution.

5. A hollow mesoporous carbon sphere prepared by the method according to claim 1, characterized in that: The hollow mesoporous carbon spheres having uniform mesopore distribution are prepared according to the method of claim 1.

6. An application of the hollow mesoporous carbon sphere according to claim 1, characterized in that: The hollow mesoporous carbon spheres are used in preparing fuel cell catalysts.

7. A rare earth metal-doped platinum alloy catalyst, characterized in that: The catalyst is a platinum alloy doped with a rare earth metal loaded on the hollow mesoporous carbon spheres as claimed in claim 1, wherein the theoretical content of platinum accounts for 5-30% of the final catalyst mass.

8. A method for preparing the catalyst according to claim 7, characterized in that: Platinum salt, transition metal salt and rare earth metal salt solution are added to the hollow mesoporous carbon spheres described in claim 1 to achieve equal volume impregnation to form a slurry. After ultrasonic treatment, the slurry is placed in a freeze dryer for drying. The dried product is then placed in a tubular furnace and calcined in an atmosphere of H2 / Ar mixed gas. The catalyst can be obtained after cooling to room temperature.

9. The method for preparing the catalyst according to claim 8, characterized in that: The platinum salt, transition metal salt and rare earth metal salt are added to the solvent; wherein the platinum salt, transition metal salt and rare earth metal salt are used in an amount distribution such that the platinum salt and the transition metal salt form a consistent alloy phase ratio of 5:1 to 1:5, and the rare earth metal element as a doping element, the ratio of the platinum salt to the rare earth metal element is 10:1 to 2:1, and the ratios are all molar atomic ratios; The solvent is one or more of distilled water, methanol, ethanol, propanol, and isopropanol; the transition metal salt is one or more of Co salt, Ni salt, Fe salt, and Cu salt; and the rare earth metal salt is one or more of Gd salt, La salt, Nd salt, Ga salt, and Er salt.

10. The method for preparing the catalyst according to claim 8 or 9, characterized in that: The ratio of the H2 / Ar mixed gas is 1 / 99 to 20 / 80; the temperature of the calcination treatment is 300 to 1000°C; and the time of the calcination treatment is 0.5 to 10 hours.

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