A core-shell structured nanocatalyst, a preparation method and use thereof

Abstract

The application discloses a core-shell structure nanometer catalyst, a preparation method and application, wherein the preparation method comprises the following steps: step one, dispersing a carbon carrier in a solution, adding a metal chelating agent, and then adding a non-noble metal precursor to load the non-noble metal precursor on the carbon carrier; step two, after removing the solvent from the solution obtained in step one, performing a first heat reduction to obtain a carbon carrier loaded with a non-noble metal inner core; step three, dispersing the carbon carrier loaded with the non-noble metal inner core in a solution, and adding a platinum precursor; and step four, after removing the solvent from the solution obtained in step three, performing a second heat reduction to obtain a core-shell structure nanometer catalyst with a platinum shell. The core-shell structure nanometer catalyst provided by the application has excellent electrocatalytic oxygen reduction activity and stability.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials, specifically to a core-shell structured nanocatalyst, its preparation method, and its applications. Background Technology

[0002] A proton exchange membrane fuel cell (PEMFC) is an energy conversion device that directly converts the chemical energy generated by the electrochemical reaction of hydrogen and oxygen into electrical and thermal energy. It features good low-temperature performance, is environmentally friendly and pollution-free, has low noise, and high conversion efficiency. A standalone PEMFC stack mainly consists of bipolar plates, a gas diffusion layer, and a membrane electrode assembly (MEA). The MEA, as the core component of the PEMFC, is generally composed of a proton exchange membrane, a catalyst layer, a microporous layer, and carbon fiber paper. Currently, the performance of PEMFCs is mainly limited by the oxygen reduction catalyst at the cathode. Therefore, one important way to improve PEMFC performance is to prepare highly active oxygen reduction catalysts to reduce the activation polarization loss of the fuel cell. Summary of the Invention

[0003] The purpose of this invention is to provide a catalyst with excellent electrocatalytic oxygen reduction activity and stability.

[0004] To achieve the above objectives, the present invention provides a method for preparing a core-shell structured nanocatalyst, comprising:

[0005] Step 1: Disperse the carbon support in a solution, add a metal chelating agent, and then add a non-precious metal precursor to load the non-precious metal precursor onto the carbon support.

[0006] Step 2: After removing the solvent from the solution obtained in Step 1, perform a thermal reduction to obtain a carbon support loaded with a non-noble metal core.

[0007] Step 3: Disperse the carbon support with the non-noble metal core in a solution and add a platinum precursor;

[0008] Step four: After removing the solvent from the solution obtained in step three, a second thermal reduction is performed to obtain a core-shell structured nanocatalyst with a platinum shell.

[0009] Optionally, the primary thermal reduction is carried out under vacuum or in a mixed atmosphere of one or more gases selected from hydrogen, nitrogen, argon, methane, acetylene, ethane, propane, ammonia, and carbon monoxide. The temperature of the primary thermal reduction is 750-900℃, and the thermal reduction time is 0.5-4h.

[0010] Optionally, the secondary thermal reduction is carried out in a mixed atmosphere of hydrogen and argon; the temperature of the secondary thermal reduction is 150-200℃, and the thermal reduction time is 0.5-2h.

[0011] Optionally, the non-precious metal precursor includes three or more of the following: metal halide salts, metal acetate salts, metal nitrate salts, or metal complex salts of Co, Ni, Fe, Cu, and Mn.

[0012] The non-precious metal precursors are added to the solution sequentially; the time interval between the addition of each non-precious metal precursor to the solution is not less than 15 minutes.

[0013] Optionally, in step one, the carbon support is dispersed in an aqueous solution of an alcohol, the alcohol including one or more of ethanol, n-propanol, isopropanol or n-butanol; the carbon support includes one or more of carbon black or graphite; the metal chelating agent is one or more of 1,10-phenanthroline, sodium citrate, and ethylenediaminetetraacetic acid.

[0014] In step three, the carbon support loaded with the non-precious metal core is dispersed in an aqueous solution of alcohol, including one or more of ethanol, n-propanol, isopropanol or n-butanol.

[0015] Optionally, the platinum precursor includes one or more of H2PtCl6, K2PtCl4, ammonium chloroplatinate, and platinum acetylacetonate.

[0016] Optionally, the metal chelating agent is 0.5-10% by mass relative to the carbon support;

[0017] The mass percentage of the metal in the non-precious metal precursor relative to the mass percentage of the carbon support is 5-30%.

[0018] The mass percentage of platinum in the platinum precursor relative to the mass percentage of the carbon support is 1-10%.

[0019] The present invention also provides a core-shell structured nanocatalyst, which is prepared by the above-described method for preparing core-shell structured nanocatalysts.

[0020] Optionally, it includes a non-precious metal core and a platinum shell encasing the non-precious metal core;

[0021] The core-shell structured nanocatalyst has a particle size of 2-5 nm;

[0022] The non-precious metal atoms in the non-precious metal core are Fe, Co, Ni and Cu, and the ratio of non-precious metal atoms is Fe:Co:Ni:Cu = 1:1:1:(0-1).

[0023] The present invention also provides an application of the above-mentioned core-shell structured nanocatalyst in the cathode of a fuel cell.

[0024] The beneficial effects of this invention are as follows:

[0025] (1) This invention provides a new method for preparing core-shell structured nanocatalysts. Compared with other methods such as liquid-phase reduction, the alloys prepared by this method have higher crystallinity, resulting in higher stability of the synthesized catalyst.

[0026] (2) Compared with other methods that are only applicable to the synthesis of a single type of core-shell structured nanocatalyst, the present invention is applicable to a wide variety of core-shell structured nanocatalysts. It can use a variety of non-precious metal elements as the core of the catalyst, and the performance of the catalyst can be adjusted by adjusting the proportion of non-precious metal elements. For example, the tensile / compressive strain of the platinum shell can be adjusted by adjusting the proportion of non-precious metal elements, thereby obtaining a core-shell structured nanocatalyst with high oxygen reduction activity. Attached Figure Description

[0027] Figures 1-5 The images show the morphology and elemental distribution of the core-shell structured nanocatalysts prepared in Examples 1-5 of this invention.

[0028] Figure 6 The X-ray diffraction patterns are those of the core-shell structured nanocatalysts prepared in Examples 1-5 of this invention.

[0029] Figure 7 The current-potential curves related to the rotation rate of the core-shell structured nanocatalysts prepared in Examples 1-5 of this invention and commercial Pt / C are shown.

[0030] Figure 8 Koutecky-Levich curves of the core-shell structured nanocatalysts prepared in Examples 1-5 of this invention and commercial Pt / C.

[0031] Figure 9 The diagram shows the mass activity, electrochemical active area, and specific activity of the core-shell structured nanocatalysts and commercial Pt / C prepared in Examples 1-5 of this invention.

[0032] Figure 10 The ORR polarization curves of the core-shell structured nanocatalysts prepared in Examples 1-5 of this invention and commercial Pt / C were repeated in the stability test.

[0033] Figure 11 This diagram illustrates the changes in mass activity and specific activity of the core-shell structured nanocatalysts and commercial Pt / C prepared in Examples 1-5 of this invention during stability testing.

[0034] Figure 12 For stability testing of Pt@FeCoNiCu 0.75 TEM and HR-TEM images of core-shell structured nanocatalysts.

[0035] Figure 13The IVP performance curves obtained by testing the core-shell structured nanocatalysts prepared in Examples 1-5 of this invention as cathode catalysts for hydrogen-oxygen fuel cells. Detailed Implementation

[0036] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This invention provides a method for preparing core-shell structured nanocatalysts, comprising:

[0038] Step 1: Disperse the carbon support in a solution, add a metal chelating agent, and then add a non-precious metal precursor, so that the non-precious metal precursor is loaded onto the carbon support.

[0039] In some embodiments, the carbon support is dispersed in an aqueous solution of an alcohol, including one or more of ethanol, n-propanol, isopropanol, or n-butanol; the carbon support includes one or more of carbon black or graphite; the metal chelating agent is one or more of 1,10-phenanthroline, sodium citrate, or ethylenediaminetetraacetic acid; the mass percentage of the metal chelating agent relative to the carbon support is 0.5-10%. The non-precious metal precursor includes three or more of the following: metal halide salts, metal acetates, metal nitrates, or metal double salts of Co, Ni, Fe, Cu, and Mn; the mass percentage of the metal in the non-precious metal precursor relative to the carbon support is 5-30%; the non-precious metal precursors are added to the solution sequentially; the time interval between the addition of each non-precious metal precursor to the solution is not less than 15 minutes.

[0040] In some embodiments, the carbon support is dispersed in an aqueous alcohol solution by ultrasound for 30-150 minutes; the non-precious metal precursor is uniformly loaded onto the carbon support by stirring and high-speed shearing for 30-150 minutes.

[0041] Step 2: After removing the solvent from the solution obtained in Step 1, perform a thermal reduction to obtain a carbon support loaded with a non-noble metal core.

[0042] The primary thermal reduction is carried out under vacuum or in a mixed atmosphere of one or more gases selected from hydrogen, nitrogen, argon, methane, acetylene, ethane, propane, ammonia, and carbon monoxide. The temperature of the primary thermal reduction is 750-900℃, and the thermal reduction time is 0.5-4h.

[0043] In some embodiments, the primary thermal reduction is carried out in a tubular furnace.

[0044] Step 3: Disperse the carbon support with the non-noble metal core in a solution and add a platinum precursor.

[0045] In some embodiments, the carbon support with the non-noble metal core is dispersed in an aqueous solution of an alcohol, including one or more of ethanol, n-propanol, isopropanol, or n-butanol. The platinum precursor includes one or more of H₂PtCl₆, K₂PtCl₄, ammonium chloroplatinate, and platinum acetylacetonate. The mass percentage of platinum in the platinum precursor relative to the mass of the carbon support is 1-10%.

[0046] In some embodiments, the carbon support loaded with a non-precious metal core is dispersed in a solution by ultrasound for 60-180 minutes.

[0047] Step four: After removing the solvent from the solution obtained in step three, a second thermal reduction is performed to obtain a core-shell structured nanocatalyst with a platinum shell.

[0048] The secondary thermal reduction is carried out in a mixed atmosphere of hydrogen and argon; the temperature of the secondary thermal reduction is 150-200℃, and the thermal reduction time is 0.5-2h.

[0049] In some embodiments, the secondary thermal reduction is carried out in a tube furnace. After the secondary thermal reduction, the catalyst is centrifuged and dried in sequence to obtain a core-shell structured nanocatalyst with a platinum shell.

[0050] In some embodiments, in steps two and four, the solvent removal method is freeze-drying, natural air drying, baking, water bath evaporation, or oil bath evaporation. Optionally, the solvent is removed by freeze-drying, followed by freezing with liquid nitrogen and then placing it in a freeze dryer with a vacuum degree <100 Pa.

[0051] Through steps one through four described above, a core-shell structured nanocatalyst is obtained. This catalyst has a particle size of 2-5 nm and comprises a non-precious metal core and a platinum shell encapsulating the non-precious metal core. The mass percentage of the metal component is 6-40%, and the mass percentage of the carbon support is 60-94%. This core-shell structured nanocatalyst exhibits excellent activity and stability for the oxygen reduction reaction (ORR).

[0052] In some embodiments, the non-noble metal atoms in the non-noble metal core are Fe, Co, Ni and Cu, and the ratio of non-noble metal atoms is Fe:Co:Ni:Cu = 1:1:1:(0-1).

[0053] The catalyst provided by this invention has a two-layer structure formed by sequentially loading a non-precious metal core and a platinum shell encapsulating the non-precious metal core on the outside of a carbon support. Existing technologies form a three-layer structure on the outside of the carbon support. The decrease in activity of platinum-based oxygen reduction catalysts is mainly due to the dissolution of non-precious metal elements. Compared with the three-layer structure, the core-shell nanocatalyst of this invention has a platinum shell on its surface, and the core alloy is composed of multiple elements, resulting in a higher entropy value and higher stability, which can effectively prevent the dissolution of the non-precious metal elements in the core during actual use. The three-layer core-shell catalyst has lower controllable consistency in preparation, making this invention more technically feasible. Furthermore, the more layers in the core-shell structure, the less thermodynamically unstable its state. Therefore, the three-layer core-shell catalyst is more easily oxidized and deactivated by oxygen at high potentials than the two-layer structure, meaning the two-layer core-shell catalyst has higher stability.

[0054] Example 1

[0055] Step 1: Disperse 20 mg of carbon black in a mixed solvent of ultrapure water and ethanol using an ultrasonic cleaner for 2 hours. Then, add 2 mg of 1,10-phenanthroline to the dispersed carbon black solution and ultrasonically disperse for another 2 hours. Next, add non-precious metal precursors in the following order: Fe(NO3)3·9H2O, Ni(NO3)2·6H2O, and Co(NO3)2·6H2O. Each non-precious metal precursor is added at 15-minute intervals to avoid direct reduction of the metal salt. The atomic ratio of the non-precious metals is Fe:Co:Ni = 1:1:1, and the total loading of non-precious metals is 4 mg. Stir for 60 minutes and then perform high-speed shearing for 60 minutes to ensure uniform loading of the non-precious metal precursors onto the carbon support.

[0056] Step 2: In the ultrasonic system, the solvent is evaporated to dryness at 50℃. Then, the carbon black containing the non-precious metal precursor is pyrolyzed and reduced at 900℃ in an H2 / N2 atmosphere for 2 hours to obtain a carbon support loaded with a non-precious metal core FeCoNi.

[0057] Step 3: The carbon support with the non-precious metal core is redispersed in a mixed solvent of ultrapure water and ethanol using an ultrasonic cleaner. A certain amount of H2PtCl6·6H2O is added, wherein the Pt loading is 10wt% relative to the mass of the carbon support added in the first step.

[0058] Step 4: In an ultrasonic system, the solvent is evaporated to dryness at 50℃. The second-loaded sample is then pyrolyzed and reduced at 200℃ in an H2 / N2 atmosphere for 1 hour. After centrifugation, washing, and drying, a Pt@FeCoNi core-shell structured nanocatalyst with a platinum shell is obtained.

[0059] Figure 1 These are morphological images and elemental distribution diagrams of Pt@FeCoNi core-shell structured nanocatalysts.

[0060] Example 2

[0061] In Example 2, the non-noble metal precursors from step one were added sequentially in the order of Fe(NO3)3·9H2O, Ni(NO3)2·6H2O, Co(NO3)2·6H2O, and Cu(NO3)2·3H2O, with a non-noble metal atomic ratio of Fe:Co:Ni:Cu = 1:1:1:0.25. The remaining reaction conditions were the same as in Example 1. Pt@FeCoNiCu was obtained. 0.25 The morphology and elemental distribution of core-shell structured nanocatalysts are as follows: Figure 2 As shown.

[0062] Example 3

[0063] In Example 3, the non-noble metal atomic ratio was Fe:Co:Ni:Cu = 1:1:1:0.50, and the remaining reaction conditions were the same as in Example 2. Pt@FeCoNiCu was obtained. 0.50 The morphology and elemental distribution of core-shell structured nanocatalysts are as follows: Figure 3 As shown.

[0064] Example 4

[0065] In Example 4, the non-noble metal atomic ratio was Fe:Co:Ni:Cu = 1:1:1:0.75, and the remaining reaction conditions were the same as in Example 2. Pt@FeCoNiCu was obtained. 0.75 The morphology and elemental distribution of core-shell structured nanocatalysts are as follows: Figure 4 As shown.

[0066] Example 5

[0067] In Example 5, the non-noble metal atomic ratio was Fe:Co:Ni:Cu = 1:1:1:1, and the remaining reaction conditions were the same as in Example 2. The morphology and elemental distribution of the Pt@FeCoNiCu1 core-shell nanocatalyst obtained are shown below. Figure 5 As shown.

[0068] Figure 6 The X-ray diffraction patterns are those of the core-shell structured nanocatalysts prepared in Examples 1-5 of this invention. Figure 6 The crystal characteristic peaks of these core-shell structured nanocatalysts are very sharp, indicating that these core-shell structured nanocatalysts have a high degree of crystallinity. Furthermore, with changes in the type and content of elements in the non-noble metal core (…),… Figure 6 b) The characteristic peaks of the crystal plane have a slight shift, indicating that tensile / compressive strain has occurred inside.

[0069] The core-shell nanocatalysts from Examples 1-5 and commercial Pt / C were subjected to LSV testing in an oxygen-saturated 0.1M HClO4 solution over a potential range of +0.05 to +1.00 V (vs RHE) at a scan rate of 5 mV / s. -1 The rotational speeds of the rotating disk electrode are 400, 600, 900, 1200, 1600, and 2000 revolutions per minute (rpm). Figure 7 The values ​​of a and f represent the linear voltammetric scan (LSV) curves of the core-shell structured nanocatalysts prepared in Examples 1-5 and commercial Pt / C at different rotational speeds. The results show that the half-wave potential (E) of these catalysts... 1 / 2 The values ​​are commercial Pt / C (0.869V), Pt@FeCoNi (0.844V), and Pt@FeCoNiCu, respectively. 0.25 (0.857V), Pt@FeCoNiCu 0.50 (0.881V), Pt@FeCoNiCu 0.75 (0.917V), Pt@FeCoNiCu1 (0.821V), indicating that Pt@FeCoNiCu 0.75 Core-shell structured nanocatalysts possess the best oxygen reduction (ORR) catalytic performance. Figure 8 The figures a and f represent the current versus rotational speed curves for the core-shell nanocatalysts prepared in Examples 1-5 and commercial Pt / C at different voltages. Based on the slope of the Koutecky-Levich curves, the ORR electron transfer number (n) for these catalysts at 0.8-0.9 V was calculated to be close to 4.0. This result indicates that the ORR occurring on the surface of these catalysts follows a 4-electron reaction pathway. Figure 9 The diagrams show the mass activity (MA), electrochemical active surface area (ECSA), and specific activity (SA) of the core-shell structured nanocatalysts prepared in Examples 1-5 and commercial Pt / C, respectively. (Pt@FeCoNiCu) 0.75 The catalyst exhibited the highest MA (0.18 A mg) at 0.9 V (vs RHE). Pt -1 ), is Pt@FeCoNi (0.055A mg ), Pt -1 ) and commercial Pt / C (0.11A mg) Pt -1 3.3 times and 1.6 times that of Pt@FeCoNiCu 0.75 It also exhibited the highest initial ECSA (46.03m). 2 gPt -1 At 0.9V (vs RHE), Pt@FeCoNiCu 0.75 SA value (0.40 mAcm) -2 Compared to Pt@FeCoNiCu 0.50 (0.45mAcm -2 Slightly lower, which is attributed to Pt@FeCoNiCu 0.50 With a smaller ECSA (30.43m) 2 g Pt -1 ). Figure 10 The af curves are linear voltammetric scans (LSV) of the core-shell nanocatalysts prepared in Examples 1-5 and commercial Pt / C, measured at intervals during durability testing. The E values ​​of the Pt@FeCoNi and Pt@FeCoNiCu1 core-shell nanocatalysts are also shown. 1 / 2 The positive displacements of 7mV and 25mV are shown respectively, Pt@FeCoNiCu 0.25 Pt@FeCoNiCu 0.50 E and commercial Pt / C 1 / 2 They showed significantly reduced negative displacements of 111, 15, and 54 mV, respectively, while Pt@FeCoNiCu 0.75 E of catalyst 1 / 2 The negative displacement was only 1 mV after 30,000 cycles. The mass activity (MA) and specific activity (SA) of the catalyst better reflect the change in ORR activity during durability testing. Figure 11 The values ​​of a and f represent the MA and SA of the core-shell structured nanocatalysts prepared in Examples 1-5 and commercial Pt / C, respectively, tested at certain intervals during the durability test. Among them, Pt@FeCoNiCu... 0.75 The core-shell structured nanocatalyst maintained a stability of 0.17 A mg after stability testing. Pt -1 Mass activity and 0.27 mAcm -2 Specific activity. Figure 12 For stability testing of Pt@FeCoNiCu 0.75 TEM and HR-TEM images of the core-shell structured nanocatalyst, from which the stability test results of Pt@FeCoNiCu can be obtained. 0.75 The structure of the particles on the core-shell structured nanocatalyst did not change significantly, indicating that the structure of Pt@FeCoNiCu did not change significantly. 0.75 Core-shell structured nanocatalysts are relatively stable.

[0070] Figure 13These are performance test graphs of the core-shell structured nanocatalysts prepared in Examples 1-5 applied to the membrane electrode cathode of a hydrogen-oxygen fuel cell. The membrane electrodes prepared with these catalysts achieved performance at 1500 mA / cm². -2 The voltages at the current densities are Pt@FeCoNi (0.527V) and Pt@FeCoNiCu, respectively. 0.25 (0.474V), Pt@FeCoNiCu 0.50 (0.527V), Pt@FeCoNiCu 0.75 (0.621V), Pt@FeCoNiCu1 (0.606V), power densities of Pt@FeCoNi (790.5mW / cm²) and Pt@FeCoNi (0.621V) are respectively. -2 ), Pt@FeCoNiCu 0.25 (711mW cm -2 ), Pt@FeCoNiCu 0.50 (790.5mW cm -2 ), Pt@FeCoNiCu 0.75 (931.5mW cm -2 ), Pt@FeCoNiCu1(909mW cm -2 The above results indicate that Pt@FeCoNiCu in these core-shell structured nanocatalysts... 0.75 It has the best performance and is expected to be used as a cathode catalyst in the membrane electrode assembly of hydrogen-oxygen fuel cells.

[0071] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing a core-shell structured nanocatalyst, characterized in that, include: Step 1: Disperse the carbon support in a solution, add a metal chelating agent, and then add a non-precious metal precursor to load the non-precious metal precursor onto the carbon support. The non-precious metal precursor includes three or more of the following: metal halide salts, metal acetates, metal nitrates, or metal complex salts of Co, Ni, Fe, Cu, and Mn. The non-precious metal precursors are added to the solution sequentially. The time interval between adding each non-precious metal precursor to the solution is no less than 15 minutes. Step 2: After removing the solvent from the solution obtained in Step 1, perform a thermal reduction to obtain a carbon support loaded with a non-noble metal core. Step 3: Disperse the carbon support with the non-noble metal core in a solution and add a platinum precursor; Step four: After removing the solvent from the solution obtained in step three, a second thermal reduction is performed to obtain a core-shell structured nanocatalyst with a platinum shell.

2. The method for preparing the core-shell structured nanocatalyst as described in claim 1, characterized in that, The primary thermal reduction is carried out under vacuum or in a mixed atmosphere of one or more gases selected from hydrogen, nitrogen, argon, methane, acetylene, ethane, propane, ammonia, and carbon monoxide. The temperature of the primary thermal reduction is 750-900℃, and the thermal reduction time is 0.5-4h.

3. The method for preparing the core-shell structured nanocatalyst as described in claim 1, characterized in that, The secondary thermal reduction is carried out in a mixed atmosphere of hydrogen and argon; the temperature of the secondary thermal reduction is 150-200℃, and the thermal reduction time is 0.5-2h.

4. The method for preparing the core-shell structured nanocatalyst as described in claim 1, characterized in that, In step one, the carbon support is dispersed in an aqueous solution of an alcohol, including one or more of ethanol, n-propanol, isopropanol, or n-butanol; the carbon support includes one or more of carbon black or graphite; and the metal chelating agent is one or more of 1,10-phenanthroline, sodium citrate, or ethylenediaminetetraacetic acid. In step three, the carbon support loaded with the non-precious metal core is dispersed in an aqueous solution of alcohol, including one or more of ethanol, n-propanol, isopropanol or n-butanol.

5. The method for preparing the core-shell structured nanocatalyst as described in claim 1, characterized in that, The platinum precursor includes one or more of H2PtCl6, K2PtCl4, ammonium chloroplatinate, and platinum acetylacetonate.

6. The method for preparing the core-shell structured nanocatalyst as described in claim 1, characterized in that, The metal chelating agent has a mass percentage of 0.5-10% relative to the carbon support; The mass percentage of the metal in the non-precious metal precursor relative to the mass percentage of the carbon support is 5-30%. The mass percentage of platinum in the platinum precursor relative to the mass percentage of the carbon support is 1-10%.

7. A core-shell structured nanocatalyst, characterized in that, The core-shell structured nanocatalyst was prepared by the method described in any one of claims 1-6.

8. The core-shell structured nanocatalyst as described in claim 7, characterized in that, It includes a non-precious metal core and a platinum shell encasing the non-precious metal core; The core-shell structured nanocatalyst has a particle size of 2-5 nm; The non-precious metal atoms in the non-precious metal core are Fe, Co, Ni and Cu, and the ratio of non-precious metal atoms is Fe:Co:Ni:Cu=1:1:1:(0-1).

9. Use of a core-shell structured nanocatalyst as described in claim 7 or 8 in a fuel cell cathode.

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