A nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst and its preparation method and application

Abstract

The present application relates to a nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst and its preparation method and application, and belongs to the field of catalyst preparation technology. The preparation method of the electrocatalyst of the present application comprises the following steps: S1, dissolving dimethylimidazole in methanol I, marked as solution A; dissolving zinc salt, platinum salt and calcium salt together in methanol II, marked as solution B; pouring solution B into solution A, and vigorously stirring to form a uniformly dispersed solution; S2, hydrothermally reacting the uniformly dispersed solution, and naturally cooling to room temperature after the reaction is completed, centrifuging, washing and vacuum drying the product to obtain a Pt‑Ca‑ZIF8 precursor; S3, grinding the Pt‑Ca‑ZIF8 precursor to granular form, adding sodium chloride, performing high-temperature pyrolysis under a protective atmosphere, stirring, washing, filtering and vacuum drying to obtain a nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst. The electrocatalyst of the present application reduces the price cost while maintaining excellent performance and stability.

Description

Technical Field

[0001] The present application relates to the technical field of catalyst preparation, and in particular to a nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Electrocatalytic reaction is a method that uses an external electric potential to promote chemical reactions. It is green and efficient and can be used in the fields of catalytic organic synthesis, electrolysis of water to produce hydrogen, electrochemical energy storage, etc. The principle of electrocatalytic reaction is to introduce electrons, cations or anions by applying an external electric field, thereby changing the thermodynamic and kinetic processes of the reaction, accelerating the reaction rate and improving the reaction selectivity. Electrocatalytic reaction technology has broad application prospects in the fields of environmental protection and energy. Especially in the field of new energy, electrocatalytic reaction technology has become an important means of preparing efficient, clean and sustainable energy. The research on electrocatalytic reactions involves the fields of chemistry, physics, biology and other interdisciplinary fields, and new electrocatalytic reaction systems and new electrocatalysts are constantly emerging.

[0003] Diatom catalysts can be effectively linked by exploiting various interactions between two metal atoms. Compared to single-atom catalysts, diatomic catalysts offer advantages such as larger atomic loadings, enhanced interactions between diatomic sites, and a wider range of catalytic applications. The most prominent of these are the interactions between diatomic sites: synergistic effects, distance enhancement effects, and electronic effects. The interactions between diatomic sites are not simply a simple superposition of individual atomic functions but also help to modulate the electronic structure of catalytically active sites, effectively improving catalytic performance for multiple advanced applications. Since the concept of single-atom catalysts (SACs) was proposed in 2011, the controllable design of SACs, including coordination and electronic structure, has been fully developed. Due to the small contact area of ​​SACs and the relatively weak interactions between atoms and supports, they provide the necessary space and possibilities for the development of high-performance diatomic catalysts (DACs) with synergistic electronic enhancement effects, which have broad application prospects in multiple fields such as thermocatalysis, photocatalysis, and electrocatalysis. Summary of the Invention

[0004] In view of this, the present application provides a nitrogen-doped carbon-loaded Pt / Ca bimetallic atom electrocatalyst, its preparation method and application. The nitrogen-doped carbon-loaded Pt / Ca bimetallic atom electrocatalyst has excellent performance, good stability and low cost. Through the active sites constructed by the bimetal and the atomic utilization rate close to 100%, the activity of the electrocatalytic oxygen reduction reaction in an alkaline environment is significantly improved, which can effectively overcome the defects of the above-mentioned prior art.

[0005] The first aspect of the present application provides a method for preparing a nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst, comprising the following steps:

[0006] S1. Dissolve dimethylimidazole in methanol I and disperse by ultrasonication, labeled as solution A; dissolve zinc salt, platinum salt, and calcium salt in methanol II and disperse by ultrasonication, labeled as solution B; pour solution B into solution A and stir vigorously to form a uniformly dispersed solution;

[0007] S2. Perform a hydrothermal reaction on the uniformly dispersed solution, and after the reaction is completed, the temperature is naturally cooled to room temperature. The product is centrifuged, washed, and vacuum-dried to obtain a Pt-Ca-ZIF8 precursor;

[0008] S3. Grind the Pt-Ca-ZIF8 precursor into granules, add sodium chloride powder, and perform high-temperature pyrolysis under a protective atmosphere. Dissolve the pyrolyzed powder in deionized water, stir, wash, filter, and vacuum dry to obtain a nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst.

[0009] Preferably, in step S2, the temperature of the hydrothermal reaction is 120-130° C., and the time of the hydrothermal reaction is 5-6 hours.

[0010] Preferably, in step S2, the specific process of washing is: first washing the precipitate after centrifugation with a dimethylformamide solution until the supernatant is colorless; and then washing with anhydrous methanol for 3 times.

[0011] Preferably, in step S2, the vacuum drying temperature is 60-65° C., and the vacuum drying time is 8-10 h.

[0012] Preferably, in step S3, the specific process of high-temperature pyrolysis is: placing the material in a tube furnace under argon protection at a rate of 5°C / min to 900-1000°C for 2 hours. Preferably, the temperature is raised to 900°C.

[0013] Preferably, in step S3, the mass ratio of the sodium chloride powder to the Pt-Ca-ZIF8 precursor is 1:1; or

[0014] The ratio of the pyrolyzed powder to deionized water is (10 mg to 100 mg): (100 to 1000 ml) or

[0015] The stirring and washing time is 1 to 2 hours; the vacuum drying temperature is 60 to 65° C., and the drying time is 5 to 6 hours.

[0016] Preferably, in step S1, the ultrasonic dispersion time of solution A and solution B is 10 to 15 minutes; and the vigorous stirring time of the uniformly dispersed solution is 1 to 2 hours.

[0017] Preferably, in step S1, the ratio of dimethylimidazole, zinc salt, platinum salt and calcium salt is 16mmol:4mmol:0.2mmol:0.1mmol; or

[0018] The zinc salt is zinc nitrate hexahydrate, the platinum salt is platinum acetylacetonate, and the calcium salt is calcium chloride; or

[0019] The concentration of the dimethylimidazole in methanol I is 1.6-2 mm, the concentration of the mixture of zinc salt, platinum salt and calcium salt in methanol II is 0.15-0.2 mm, and the usage ratio of methanol I to methanol II is 10 ml:30 ml.

[0020] The second aspect of the present application also provides a nitrogen-doped carbon-supported Pt / Ca atomic electrocatalyst, which is prepared by the above-mentioned method.

[0021] The third aspect of the present application also provides the use of the above-mentioned nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst in the redox reaction of alkaline electrolyte.

[0022] Compared with the prior art, this application has the following beneficial effects:

[0023] (1) In this application, a bimetallic atomic structure of platinum single atoms and calcium single atoms is prepared on a nitrogen-doped carbon substrate by systematically controlling process parameters such as synthesis temperature and addition of sodium chloride powder. The general formula of the structure is Pt-Ca-NC, where NC is a nitrogen-doped carbon substrate material, and the Pt metal atoms and Ca metal atoms are anchored to the carbon substrate by nitrogen.

[0024] (2) Compared with other platinum-based bimetallic atom catalysts, the nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst in this application introduces calcium, one of the alkaline earth metal elements, into the Pt-Ca-NC synthesized in this application for heterogeneous catalysis, thereby reducing the price cost while maintaining excellent performance and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following briefly introduces the drawings required for use in the description of the present application or the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] Figure 1 This is a characterization diagram of the morphology and coordination environment of the Pt-Ca-NC catalyst prepared in Example 1 of the present application; Figure 1 (a) is a TEM image; Figure 1 (b) is the HAADF-STEM image, Figure 1 (c) is the XRD pattern;

[0027] Figure 2 This is the STEM-EDX image of Pt-Ca-NC prepared in Example 1 of the present application;

[0028] Figure 3 ORR-LSV curves of Pt-Ca-NC prepared in Example 1 of the present application, Pt-NC, Ca-NC, NC prepared in Comparative Examples 1-3, and commercial Pt / C in 0.1 M KOH;

[0029] Figure 4 Current-time stability test of the Pt-Ca-NC prepared in Example 1 of the present application, the Pt-NC and Ca-NC prepared in Comparative Examples 1-2, and commercial Pt / C at a rotating disk speed of 1600 rpm;

[0030] Figure 5 This is a current-time stability test of the Pt-Ca-NC prepared in Example 1 of the present application at zero rotation speed on a rotating disk;

[0031] Figure 6 Durable cycle stability test of Pt-Ca-NC prepared in Example 1 of the present application;

[0032] Figure 7 ORR-LSV curves of Pt-Ca-NC prepared in Example 1, Pt-Ca-NC-2 prepared in Example 2, and Pt-Ca-NC-3 prepared in Example 3 in 0.1 M KOH of the present application. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0034] Unless otherwise specified, the experimental methods used in the examples of this application are all conventional methods.

[0035] In the following examples and comparative examples, unless otherwise specified, all raw materials can be purchased commercially or prepared by conventional methods.

[0036] Example 1

[0037] The preparation method of the Pt-Ca-NC catalyst of this embodiment includes the following steps:

[0038] Dissolve 16 mmol of 2-methylimidazole in 10 ml of methanol and dissolve by ultrasonic dispersion for 10 minutes. This is labeled Solution A. Dissolve 4 mmol of Zn(NO₃)₂*6H₂O, 0.2 mmol of Pt(acac)₂, and 0.1 mmol of CaCl₂ in 30 ml of methanol and dissolve by ultrasonic dispersion for 10 minutes. This is labeled Solution B. Pour Solution B into Solution A and stir vigorously for 1 hour. Transfer the mixture to a hydrothermal reactor and heat it in an oven at 120°C for 5 hours. Allow the mixture to cool to room temperature naturally. Centrifuge the product and wash the precipitate with DMF until the supernatant is colorless. Then wash it three times with anhydrous methanol. Transfer the washed sample to a vacuum drying oven and dry it at 60°C for 10 hours to obtain the Pt-Ca-ZIF₂ precursor. The Pt-Ca-ZIF8 precursor sample was ground into fine particles, and the sample was collected and transferred to a tube furnace. NaCl powder was weighed in a 1:1 ratio with the sample weight and placed together in the tube furnace. It was heated to 900°C at a heating rate of 5°C / min under Ar atmosphere and maintained for 2 hours for thermal decomposition. Then it was naturally cooled to room temperature. The sample was taken out and moved to a beaker. 100 ml of deionized water was added. The powder was heated to 60°C and stirred for 2 hours. The solution was then filtered. During the filtration process, an additional 1 L of deionized water was added for washing. The filtered sample was then transferred to a vacuum drying oven and dried at 60°C for 5 hours to obtain a nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst, which was recorded as Pt-Ca-NC catalyst.

[0039] like Figure 1 As shown in (a), there is no aggregation of platinum metal and calcium metal nanoparticles on the catalyst surface; Figure 1 As shown in (b), it can be seen from the figure that platinum metal and calcium metal are distributed in atomic size on the nitrogen-doped carbon substrate. Figure 1 As shown in (c), two peaks appear in the XRD pattern of the Pt-Ca-NC catalyst at around 26.5° and 42.8°, corresponding to the (002) and (100) crystal planes of carbon, respectively. The absence of diffraction peaks of platinum metal, calcium metal and its oxides indicates that platinum and calcium exist in the form of single-atom coexistence, which is consistent with the results of TEM and HAADF-STEM images.

[0040] Figure 2 The figure shows the elemental energy spectrum of STEM-EDX. As shown in the figure, there are obvious distributions of platinum and calcium elements on the nitrogen-doped carbon substrate, confirming that single platinum atoms and single calcium atoms are successfully loaded on the nitrogen-doped carbon substrate.

[0041] It can be seen that the platinum single atoms and calcium single atoms in the Pt-Ca-NC catalyst prepared in this example are anchored on the carbon substrate through nitrogen and exhibit strong electronic interaction.

[0042] Example 2

[0043] The preparation method of the Pt-Ca-NC-2 catalyst provided in this embodiment can refer to Example 1, except that the high-temperature pyrolysis temperatures of the two are different. In Example 2, heating is performed to 950°C at a heating rate of 5°C / min under Ar atmosphere as a variable.

[0044] Example 3

[0045] The Pt-Ca-NC-3 provided in this embodiment can refer to Example 1, except that the high-temperature pyrolysis temperatures of the two are different. In Example 3, the temperature is heated to 1000°C at a heating rate of 5°C / min under Ar atmosphere as a variable.

[0046] Comparative Example 1

[0047] In this comparative example, the platinum metal atoms form isolated single atomic sites with the general formula of Pt-NC. The preparation method of the Pt-NC catalyst in this comparative example includes the following steps:

[0048] Dissolve 16 mmol of 2-methylimidazole in 10 ml of methanol and dissolve by ultrasonication for 10 minutes. This is labeled Solution A. Dissolve 4 mmol of Zn(NO₃)₂*6H₂O and 0.2 mmol of Pt(acac)₂ in 30 ml of methanol and dissolve by ultrasonication for 10 minutes. This is labeled Solution B. Pour Solution B into Solution A and stir vigorously for 1 hour. Transfer the mixture to a hydrothermal oven and heat at 120°C for 5 hours, allowing it to cool to room temperature. Centrifuge the mixture, wash the precipitate with DMF until the supernatant is colorless, and then wash it three times with anhydrous methanol. Transfer the washed sample to a vacuum drying oven and dry it at 60°C for 10 hours to obtain the Pt-ZIF₃ precursor. The Pt-ZIF8 precursor sample was ground into fine particles, and the sample was collected and transferred to a tube furnace. NaCl was weighed in a 1:1 ratio with the sample weight and placed together in the tube furnace. It was heated to 900°C at a heating rate of 5°C / min under Ar atmosphere and maintained for 2 hours for thermal decomposition. Then it was naturally cooled to room temperature. The sample was taken out and moved to a beaker. 100 ml of deionized water was added. The powder was heated to 60°C and stirred for 2 hours. The solution was then filtered. During the filtration process, an additional 1 L of deionized water was added for washing. The filtered sample was then transferred to a vacuum drying oven and dried at 60°C for 5 hours to obtain a Pt-NC catalyst.

[0049] Comparative Example 2

[0050] In this comparative example, the calcium metal atom forms an isolated single atomic site with the general formula of Ca-NC. The preparation method of the Ca-NC catalyst in this comparative example includes the following steps:

[0051] Dissolve 16 mmol of 2-methylimidazole in 10 ml of methanol and dissolve by ultrasonication for 10 minutes. This is labeled Solution A. Dissolve 4 mmol of Zn(NO₃)₂*6H₂O and 0.1 mmol of CaCl₂ in 30 ml of methanol and dissolve by ultrasonication for 10 minutes. This is labeled Solution B. Pour Solution B into Solution A and stir vigorously for 1 hour. Transfer the mixture to a hydrothermal oven and heat at 120°C for 5 hours, allowing it to cool to room temperature. The product is centrifuged, and the precipitate is washed with DMF until the supernatant is colorless. The precipitate is then washed three times with anhydrous methanol. The washed sample is then dried in a vacuum oven at 60°C for 10 hours to obtain the Ca-ZIF₃ precursor. The Ca-ZIF8 precursor sample was ground into fine particles, and the sample was collected and transferred to a tube furnace. NaCl was weighed in a 1:1 ratio with the sample weight and placed together in the tube furnace. It was heated to 900°C at a heating rate of 5°C / min under Ar atmosphere and maintained for 2 hours for thermal decomposition. Then it was naturally cooled to room temperature. The sample was taken out and moved to a beaker. 100 ml of deionized water was added. The powder was heated to 60°C and stirred for 2 hours. The solution was then filtered. During the filtration process, an additional 1 L of deionized water was added for washing. The filtered sample was then transferred to a vacuum drying oven and dried at 60°C for 5 hours to obtain a Ca-NC catalyst.

[0052] Comparative Example 3

[0053] In this comparative example, a nitrogen-doped carbon substrate material with the general formula NC was prepared. The preparation method of the NC catalyst in this comparative example comprises the following steps:

[0054] Dissolve 16 mmol of 2-methylimidazole in 10 ml of methanol and dissolve by ultrasonication for 10 minutes. This is labeled Solution A. Dissolve 4 mmol of Zn(NO₃)₂*6H₂O in 30 ml of methanol and dissolve by ultrasonication for 10 minutes. This is labeled Solution B. Pour Solution B into Solution A and stir vigorously for 1 hour. Transfer the mixture to a hydrothermal oven and heat at 120°C for 5 hours, allowing it to cool to room temperature. Centrifuge the product, wash the precipitate with DMF until the supernatant is colorless, and then wash it three times with anhydrous methanol. Transfer the washed sample to a vacuum drying oven and dry it at 60°C for 10 hours to obtain the ZIF8 precursor. The ZIF8 precursor sample was ground into fine particles, and the sample was collected and transferred to a tube furnace. NaCl was weighed in a 1:1 ratio with the sample weight and placed together in the tube furnace. It was heated to 900°C at a heating rate of 5°C / min under Ar atmosphere and maintained for 2 hours for thermal decomposition. Then it was naturally cooled to room temperature. The sample was taken out and moved to a beaker. 100 ml of deionized water was added. The powder was heated to 60°C and stirred for 2 hours. The solution was then filtered. During the filtration process, an additional 1 L of deionized water was added for washing. The filtered sample was then transferred to a vacuum drying oven and dried at 60°C for 5 hours to obtain the NC catalyst.

[0055] Test Case

[0056] The Pt-Ca-NC, Pt-NC, Ca-NC, and NC catalysts prepared in Examples 1, 2, and 3, respectively, and Comparative Examples 1, 2, and 3, were tested for oxygen reduction activity in an alkaline electrolyte using a rotating disk electrode setup with a carbon rod as the counter electrode, an Ag / AgCl electrode as the reference electrode, and a glassy carbon electrode as the counter electrode. The alkaline electrolyte was 0.1 M KOH. 5 mg of the target sample was dissolved in 25 μL of Nafion, 50 μL of ultrapure water, and 425 μL of isopropanol. 10 μL of the electrode ink was then drop-coated onto the glassy carbon electrode, allowed to air dry, and electrochemical testing was performed at 1600 rpm.

[0057] The obtained oxygen reduction LSV curve is as follows Figure 3 As shown in the figure, Pt-Ca-NC exhibits the highest oxygen reduction onset potential (1.00V) and half-wave potential (0.88V), which are better than Pt-NC prepared in Comparative Example 1 (0.97V and 0.86V), Ca-NC prepared in Comparative Example 2 (0.96V and 0.79V), NC prepared in Comparative Example 3 (0.91V and 0.75V) and commercial Pt / C (0.99V and 0.84V). It can be seen that the Pt-Ca-NC catalyst prepared in this application has better oxygen reduction electrocatalytic activity under 0.1M KOH conditions.

[0058] The stability of Pt-Ca-NC prepared in Example 1 was tested in 0.1 M KOH. Figure 4 As shown in FIG, when the potential is applied to 0.77 V, the current density of the catalyst still maintains 98.74% after two hours, which is better than the Pt-NC prepared in Comparative Example 1 (95.84%), the Ca-NC prepared in Comparative Example 2 (94.16%) and the commercial Pt / C (89.98%). Figure 5 As shown in Figure 2, the Pt-Ca-NC catalyst showed no significant fluctuation within 120 h under a constant voltage test of 0.76 V (vs. RHE) with no rotating disk speed. Figure 6 As shown, after 10,000 cyclic voltammetry tests, the half-wave potential decayed by only 5 mV, indicating that the Pt-Ca-NC catalyst prepared in Example 1 exhibited excellent oxygen reduction electrocatalytic stability in 0.1 M KOH.

[0059] like Figure 7 As shown in the figure, by regulating the high-temperature pyrolysis temperature as a process parameter, the half-wave potential of the Pt-Ca-NC catalyst obtained by pyrolysis at 900°C is 0.88V, which has better oxygen reduction electrocatalytic activity than the Pt-Ca-NC-2 obtained by pyrolysis at 950°C in Example 2 (half-wave potential of 0.83V) and the Pt-Ca-NC-3 obtained by pyrolysis at 1000°C in Example 3 (half-wave potential of 0.79V), and 900°C is determined to be the optimal temperature for synthesis.

[0060] In summary, in the alkaline oxygen reduction process, the interactions between the prominent diatomic sites of the Pt-Ca-NC prepared in Example 1 of the present application: synergistic effect, distance enhancement effect and electronic effect make the Pt-Ca-NC catalyst prepared in Example 1 have excellent activity and stability in the alkaline oxygen electroreduction process.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst, characterized in that: The following steps are involved: S1. Dissolve dimethylimidazole in methanol I and disperse by ultrasonication, which is labeled as solution A. Dissolve zinc salt, platinum salt and calcium salt in methanol II and disperse them by ultrasonication, which is labeled as solution B. Pour solution B into solution A and stir vigorously to form a uniform dispersed solution. S2. Perform a hydrothermal reaction on the uniformly dispersed solution, and after the reaction is completed, the temperature is naturally cooled to room temperature. The product is centrifuged, washed, and vacuum-dried to obtain a Pt-Ca-ZIF8 precursor; S3. Grind the Pt-Ca-ZIF8 precursor into granules, add sodium chloride powder, and perform high-temperature pyrolysis under a protective atmosphere. Dissolve the pyrolyzed powder in deionized water, stir, wash, filter, and vacuum dry to obtain a nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst.

2. The method for preparing the nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst according to claim 1, characterized in that: In step S2, the temperature of the hydrothermal reaction is 120-130° C., and the time of the hydrothermal reaction is 5-6 h.

3. The method for preparing the nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst according to claim 1, characterized in that: In step S2, the specific process of washing is: first washing the precipitate after centrifugation with a dimethylformamide solution until the supernatant is colorless; and then washing with anhydrous methanol for 3 times.

4. The method for preparing the nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst according to claim 1, characterized in that: In step S2, the vacuum drying temperature is 60-65° C., and the vacuum drying time is 8-10 h.

5. The method for preparing the nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst according to claim 1, characterized in that: In step S3, the specific process of the high-temperature pyrolysis is: placing the sample in a tube furnace under argon protection and raising the temperature to 900-1000° C. at a rate of 5° C. / min for 2 h.

6. The method for preparing nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst according to claim 1, characterized in that: In step S3, the mass ratio of sodium chloride to Pt-Ca-ZIF8 precursor is 1:1; or The ratio of the pyrolyzed powder to deionized water is (10-100 mg): (100-1000 ml); or The stirring and washing time is 1 to 2 hours; the vacuum drying temperature is 60 to 65°C, and the drying time is 5 to 6 hours.

7. The method for preparing nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst according to claim 1, characterized in that: In step S1, the ultrasonic dispersion time of solution A and solution B is 10-15 minutes; the time of vigorous stirring of the uniformly dispersed solution is 1-2 hours.

8. The method for preparing nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst according to claim 1, characterized in that: In step S1, the ratio of dimethylimidazole, zinc salt, platinum salt and calcium salt is 16mmol:4mmol:0.2mmol:0.1mmol; or The zinc salt is zinc nitrate hexahydrate, the platinum salt is platinum acetylacetonate, and the calcium salt is calcium chloride; or The concentration of the dimethylimidazole in methanol I is 1.6-2 mm, the concentration of the mixture of zinc salt, platinum salt and calcium salt in methanol II is 0.15-0.2 mm, and the usage ratio of methanol I to methanol II is 10 ml:30 ml.

9. A nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst, characterized in that: A nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst prepared by the method according to any one of claims 1 to 8.

10. Use of the nitrogen-doped carbon-supported Pt / Ca bimetallic atom electrocatalyst according to claim 9 in an oxygen reduction reaction in an alkaline electrolyte.

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